GAIM Science Conference Abstracts
Updated September 15, 1995


Abstract: External Forcing of Land-Use Changes by Human Activities in Food Supply and Demand
Gilbert Ahamer,
Institute for Plant Ecology at the Justus-Liebig-University
Giessen / Germany; 1995

Abstract: In order to identify driving forces for the development of the current and future land use changes, in other words for agriculturally used area in the long term and on a global scale, an analysis of the driving forces in the system of global food demand and supply has been carried out. As a first step in direction to that target, a socio-economic database consisting of 880 variables as time series for 149 countries was designed on the basis of the FAO data and the World Bank data.

In a second step, data from different scientific areas are combined by its analytical tool that permits to derive secondary variables and to establish regressions on a per country scale between any such variables and finally to calculate trends and elasticities on a global, regional or per country level.The global system for food production is viewed from the demand side and is understood as a logical chain of subsystems being described by dimensionless intensity parameters. Results of trend analyses show the change in RAP and agricultural area to be mainly influenced from the demand side by food trade, distribution, quality and quantity of nutrition; from the supply side by the level of labour input, the degree of mechanization and fertilizer input in a given country. It is interesting to note, however, that in different regions of the earth different driving forces are predominant.

Be it mere population growth in Africa that drives the search for new agricultural land, the strong increaseof the population number is not the most pressing force: increase in food quantity, foodcomposition (the richer a nation is, the more meat is eaten) and changes in global patterns of foodtrade are dominating the search for new agricultural land in the more developed continents. For analysis of details, 19 scenarios for the area needed for future food production are proposed. Future research directions are identified: "Climate Impacts by Megatrends in Socio-economy",the vast area of energy consumption is being planned to be integrated in a future stage of the project.

SPECIES INFLUENCING ATMOSPHERIC CHEMISTRY
IN TROPICAL AFRICA

Ajit-L. N. Ajavon

Atmospheric Chemistry Laboratory, Facult des Sciences,
Universit du Bnin, B.P. 1515, Lom-TOGO


The tropospheric concentrations of most reactive chemical
species have been found to very in space and time all over
the tropical Africa. Two categories of chemical species play a
major role and are most involved in Africa tropospheric
chemistry: Aerosols and trace gases.

Aerosols originate from biomass burning, harmattan haze durst,
open-air house solid waste incineration and vehicular traffic
of unpaved as well as unswept paved roads and are composed of
TPM, POC, SOx, elemental carbon. Severe visibility reduction,
increased respiratory deceases and chest congestion complaints
are usually recorded during harmattan period.

Trace gases most of the time result from biomass burning,
engine exhausts, factory smokes. CO2, CH4, NOx, SOx, NMHC,
R(CH)x, 03 and aromatics are the major trace gases en-
countered.

These emissions to the atmosphere from both anthropogenic and
non-anthropogenic sources yield to increasing concentrations
of a number of trace gases, are responsible of Africa
temperatures increase through the greenhouse effect. The high
concentration and large scale increase of tropospheric ozone,
observed from data of field campaign experiments performed in
tropical Africa, indicate a fundamental change in the chemical
behaviour with perturbation of oxidant cycles in Africa
troposphere, leading to important photochemistry and climate
change.


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DETERIORATION OF LANDUSE DUE TO HUMAN ACTIVITIES
IN AMMAN AREA

H. Al-Kharabsheh

Royal Jordanian Geographic Centre
Amman - Jordan

To reach an understanding prognostic behaviour of global
change, we have to improve our current knowledge and pinpoint
critical gaps with components which aim to produce a simple
model of the globe.

Amman city development was taken as a case study, knowing that
Amman forms more than one-third of Jordan's population,
mediterranean climate, semi-arid area, it is located on an
important part of fertile land where it's considered as a crop
productive area. It played, until the seventies, an important
role in supplying Jordan with wheat.

Aerial photographs, maps and satellite images (Spot, Landsat)
corresponding to different dates are used in this study to
delineate the urban areas.

As a result of data analysis and image interpretation, we can
clearly see that the urbanization reduced and destroyed an
appreciable part of fertile land of Jordan. Results also show
the important impact of human activities on global change and
degradation of the earth, that allows us to survive. Also we
see the importance of resource planning and managing land
sustainably. These tools should be used by planners and
decision makers in order to protect the homosphere and
biosphere from dangerous changes.

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TOWARDS QUANTIFYING THE GLOBAL PATTERN
OF CARBON DIOXIDE FERTILIZATION EFFECT

G. A. Alexandrov1 and T. Oikawa2

1Institute of Atmospheric Physics, Russian Academy of Sciences
Pyzhevsky Per. 3,
Moscow, 109017, Russia

2Institute of Biological Sciences, Tsukuba University
Tsukuba, Ibaraki 305, Japan

It is conventional to assume that contemporary terrestrial
carbon budget includes a sink term resulted from CO2
fertilization effect. However, the empirical basis for
evaluating the magnitude of the sink is not sufficiently
strong: experimental studies show that plant response is
apparently species and site specific. In this paper we
quantify the role of biome-specific limitations such as
available solar radiation.We proceed from the model based on Monsi's principles (Oikawa,
1986), suppose that light-saturated photosynthetic rate is
proportional to atmospheric CO2 concentration (Ca), calculate
the buildup of net primary production (dNPP) per each ppmv of
Ca growth (dCa) and come to conclusion that fertilization
effect of CO2 (dNPP/dCa) is more pronounced with biomes
receiving more incident solar radiation. We estimate (Fig.)
the global dNPP/dCa at 1.5 Pg d.w./ppmv, tropical biomes
dNPP/dCa at 1 Pg d.w./ppmv and savannah dNPP/dCa at 0.5 Pg
d.w./ppmv.


[Place for Figure]


Fig. Proposed global pattern of carbon dioxide fertilization
effectThe inferred location of the sink (predominantly in the
tropical latitudes) is consistent with the indirect evidence
of the existence a tropical biotic sink that was obtained
(e.g., Enting & Mansbridge, 1991) from inverse calculatutions
using atmospheric transport models. This conclusion is also
supported by the data (Archer, 1989) on conversion of savannah
grasslands to savannah woodlands.
The obtained magnitude of CO2 fertilization effect is roughly
agreed with that was derived from 1981-1986 observations of
atmospheric carbon isotope ratio (Francey et al., 1995), but
significantly less than that was derived from 1989-1992 period
of the same observations. The causes of variations in the
magnitude of CO2 dependent terrestrial carbon sink are
discussed.References:
Archer, S (1989) Am.Nat., Vol. 134, pp. 545-561
Enting, I.G. and J.V. Mansbridge (1991) Tellus, Vol. 43,
pp.156-170 Francey, R.J. et al. (1995) Nature, Vol. 373, pp.
326-330
Oikawa, T. (1986) Bot. Mag. Tokyo, Vol. 99, pp. 419-430


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MODELLING OF MOISTURE RETENTION IN PEAT SOILS

J. Alm1, R. Weiss1, R. Laiho2 and J. Laine2

1Department of Biology, University of Joensuu
P.O. Box 111, FIN-80101 Joensuu, Finland

2Department of Forest Ecology
P.O. Box 24, FIN-00014, University of Helsinki, Finland

Water retention capacity of undisturbed surface peat samples,
collected from 38 undrained and drained pine mire sites and
four depths at each site, was measured gravimetrically for
matric potentials of pF 1.0, 1.5, 1.8, 2.0, 3.0 and 4.2. Peat
characteristics such as bulk density and botanical peat
components (remains of Sphagnum, Carex, Eriophorum and wood)
were also determined. We tested several common water retention
theories used for mineral soils, derived a semi-empirical
equivalent model for peat soil, and compared the predictions
of the most feasible models on our data. At saturation point
(pF 0), the models were defined to give the water content
calculated using the sample total porosity obtained from a
constant specific gravity value of 1.5 g cm-3 and the measured
sample bulk density.

To find the most feasible basic model types for peat soils, a
subset of 25 peat samples was used in a test run where each
model type was fitted using a non-linear regression algorithm
(sequential quadratic programming) and the prediction errors
were compared using F-statistics. Because of the few matric
potential values used, we had to reduce the number of
parameters used commonly in the models for mineral soils to
obtain higher degrees of freedom. Sensitivity analysis for the
remaining model types showed that the residual water content
of peat is only of minor importance for the matric suction
range of practical interest.

According to the F-test, the most suitable model type was the
Van Genuchten's model with the residual water content omitted:
3D s (1+(E0h)n)-1+1/n, where is volumetric peat water content
(cm3 cm-3), s is saturated soil water content, E0 and n are
shape parameters and h is matric suction value in H2Ocm (e.q.
10pF). To explain the variation in the shape parameters, we
used three different peat character sets in OLS-regression.
The first set consisted only of the polynomial terms of bulk
density; botanical peat components were added to the second
set, and an interaction term (Sphagnum-component with sampling
depth) was finally added to the third set. The variables in
the third set proved to be clearly the best predictors for E0
and n.

However, in the semi-empirical model 3D exp{ln( s) - [ln( s) -
ln( pF3D4.2)] (hpF /4.2)m} with shape parameter m, this single
shape parameter was clearly better explained by all of the
peat character sets than the two shape parameters of the Van
Genuchten model. When testing the final models by an overall
nonlinear regression, the semi-empirical model explained the
whole data set better (R23D0.93) than did the Van Genuchten
model (R23D0.90). We recommend that in pragmatic modelling
approaches the semi-empirical model should be used.

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A MECHANISTIC MODEL OF GLOBAL PHOTOSYNTHESIS

J.S. Amthor

Global Climate Research Division, Lawrence Livermore National
Laboratory
P.O. Box 808, L-256, Livermore, CA 94550, USA

The Lawrence Livermore National Laboratory, Global Climate
Research Division global terrestrial ecosystem carbon cycle
model is composed of three modules:

(1) plant photosynthesis;
(2) plant growth, respiration, and litter production; and
(3) litter and soil organic matter decomposition.

The global carbon cycle model is implemented at the spatial
scale of 1 latitude x 1 longitude. It has a nominal time step
of 1 hour. Actual vegetation cover and soil types are used.

The plant photosynthesis module, which will be described here,
is based on the biochemistry and physiology of C3 and C4
photosynthesis. The C4 photosynthesis submodel is used with
the C3 submodel for grasslands. The C3 submodel is used alone
for all other ecosystems. Effects of atmospheric [CO2] on
photosynthesis are explicitly accounted for by the module, due
to the biochemical equations used. Effects of solar radiation
(cloudiness), temperature, soil water content, and nitrogen on
CO2 assimilation are also included in the module. Canopy
conductance is calculated during the simulation of
photosynthesis, so the photosynthesis module is also used to
calculate transpiration.

Responses of global terrestrial photosynthesis to changes in
atmospheric [CO2] that have occurred during the past 200 years
will be presented. Then, photosynthetic response to a doubling
of present atmospheric [CO2] will be discussed.

The photosynthesis module is being tested at several sites
(the module is a "point" model that is applied globally as a
grid of points) with continuous measurements of whole-forest
CO2 exchange being made by the eddy correlation method. It is
also being tested with data from several field-scale
CO2-enrichment experiments.


This work was supported by Lawrence Livermore National
Laboratory's Laboratory Directed Research and Development
Program under the auspices of U.S. Department of Energy,
Environmental Sciences Division (contract No. W-7405-Eng-48).


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SPATIO-TEMPORAL LINKAGES BETWEEN NDVI AND EL NINO
OSCILLATION (ENSO) OVER AFRICA
Assaf Anyamba, J. Ronald Eastman

The Clark Labs for Cartographic Technology and Geographic
Analysis
Graduate School of Geography
950 Main St. Worcester, MA 01610, USA
During 1980s Africa has experienced prolonged periods of
drought often followed by wet phases. These variations have
been linked to low and high phases of the ENSO phenomenon. In
this study we use principal components transformation to
analyze the normalized difference vegetation index (NDVI) time
series data for Africa for the period 1986 - 1994 to
investigate spatio-temporal patterns of variation in the
vegetation index in relation climate variability. Results from
the analysis show that the NDVI data sets effectively
represents seasonal to interannual patterns of climate
variability. One spatial pattern that is centered on Botswana,
South Africa and Zimbabwe indicates strong temporal
correlations with other ENSO indicators including SOI, OLR and
SST anomalies. The patterns retrieved show areas affected by
both the 1986-1987 and 1992 droughts. These results first,
reaffirm the association between the ENSO phenomenon and
climate variability in the western dipole of the Southern
Oscillation. Second, the technique used illustrates a new
perspective for examining climate variability by extracting
separate and distinct spatial patterns from the NDVI time
series record. This offers new possibilities for a better
understanding of spatial manifestations of ENSO on the land
surface, monitoring vegetation conditions in data sparse
regions and in validating model forecasts of El Nino related
events at regional to continental scales.

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NON-STATIONARY NUMERICAL MODEL OF RADIATION
AND TEMPERATURE REGIME OF SOIL-VEGETATION-ATMOSPHERE
(SVA) SYSTEM

D.G. Atanassov

National Institute of Meteorology and Hydrology,
Blvd Tsarigradsko Chaussee 66, 1784 Sofia, Bulgaria


The main objectives of SVA modelling are the processes of
transport, photosynthesis and shortwave radiation; stationary
governing equations are usually used. To simulate the diurnal
meteorological variation of SVA system, infrared radiation and
non-stationary equation have to be included.
A one-dimensional model of horizontally homogeneous SVA system
is developed. A non-stationary equation for air temperature as
well as another one for plant temperature are used. The
source-sink terms of these equations refer to the contribution
of turbulent and radiation heat flux densities and to the
plant-air heat exchange. Goudriaan's scheme of shortwave
radiation transfer in plant canopies is applied. A new
infrared radiation scheme is developed. Linear absorption of
the irradiance on its way through the canopy is assumed,
instead of the common used exponential absorption assumption.
The soil surface temperature is calculated by the force-
restore method.

A sensitivity analysis to the canopy characteristics and to
the meteorological conditions is performed. To focus on the
radiation-heat interaction, the evaporation is not considered;
wind velocity profile and eddy exchange coefficient are
considered in a simple way. Numerical simulations show the
ability to model the complicated non-stationary and heat
transfer in SVA system.


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INTERANNUAL VARIATION OF CARBON EXCHANGE FLUXES IN TERRESTRIAL ECOSYSTEMS

F.-W. Badeck1, J. Kindermann2, G. H. Kohlmaier2

1Laboratoire d'Ecologie vgtale, Universit de Paris Sud XI,
B3t. 362, 91405 Orsay, France

2Institut f1r Physikalische und Theoretische Chemie, J. W.
Goethe Universit4t,
Marie-Curie-Str. 11, 60439 Frankfurt/M., FRG

Simulation results of the interannual variation in carbon
exchange fluxes between the atmosphere and the terrestrial
biosphere are presented. A prognostic physiologically based
model of the carbon budget in terrestrial ecosystems, the
Frankfurt Biosphere Model (FBM), is applied. Within the model
32 vegetation types are distinguished. The spatial resolution
is 0.50 x 0.50. The model simulates phenology based on a flux
balance approach and allometric relationships.
The data on climatic forcing are based on climate maps.
Interannual variation is introduced according to records of
temperature and precipitation anomalies. The model calculates
gross primary production, autotrophic respiration, net primary
production, heterotrophic respiration and the change in carbon
stocks for natural climax ecosystems.
Simulated interannual variation in the annual net exchange
flux between the atmosphere and the terrestrial biosphere is
compared to the biospheric signal deduced from 13C-measure-

ments. Biospheric activity can be identified as a major cause
of the variation in the increase of atmospheric carbon
dioxide.
The effects of the temperature response of gross primary
production and respiration as well as the response to soil
water availability are characterized. It can be shown that a
consistant correlation between mean annual temperature and net
carbon exchange can not be expected. Monthly temperature
anomalies and their effects on the duration of the vegetation
period as well as the relative changes in GPP and respiration
have to be taken into account. The same holds true for
precipitation and soil water content.

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PREDICTION OF BIOMASS AND TURNOVER TIME FOR USE IN
DIAGNOSTIC MODELS OF BIOSPHERIC CARBON EXCHANGE FLUXES

F.-W. Badeck, A. Ruimy, B. Saugier

Laboratoire d'Ecologie vgtale, Universit de Paris Sud XI,
B3t. 362, 91405 Orsay, France

With the current state of the art, many diagnostic models of
the carbon exchange fluxes of terrestrial ecosytems need
information on carbon density and turnover time in the living
biomass in order to calculate respiration, litter production
and C13 content. Yet, currently biomass can not be derived
from optical remote sensing due to saturating signals. The
technique for radar derived measurements is under development
and not yet applicable on the global scale.
We apply a prognostic global model of the terrestrial
biosphere in order to derive modules for the determination of
biomass as a function of the average gross primary production.
The Frankfurt Biosphere Model (FBM) is a global
process-oriented model of CO2 exchange between terrestrial
ecosystems and the atmosphere. The model is not confined to
the calculation of ecosystems in the climax steady state, but
can as well be used to simulate changes in carbon stocks with
growth stages. Based on this property the feasability of a
detection of non climax ecosystems will be explored.
Different methods to determine biomass for the grid elements
covered by the same vegetation type will be compared. The
sensitivity of a diagnostic model of the carbon exchange in
the terrestrial biosphere, TURC (Terrestrial Uptake and
Release of Carbon) to the resulting biomass maps will be
examined.

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ASSESSMENT OF SOIL CARBON IN CENTRAL U. S. AGROECOSYSTEMS

2T.O. Barnwell, Jr., A.S. 1Donigian, Jr., 2R.B. Jackson, IV,
1A.S. Patwardhan,
3K.B. Weinrich, 3A.L. Rowell, 1R.V. Chinnaswamy, 4C.V. Cole

1AQUA TERRA Consultants, Mountain View, CA 94043

2Environmental Research Laboratory, U.S. EPA, Athens, GA 30605

3Computer Sciences Corporation, Athens, GA 30605

4Natural Resources Ecology Laboratory, Fort Collins, CO 80523

We estimate the carbon sequestration potential for
agroecosystems of the central United States, assessing the
impact of current agricultural trends and conditions,
alternative tillage practices, cover crops, and Conservation
Reserve Program policy on soil carbon and providing evidence
of the value of agricultural residue management practices in
relation to CO2 emissions to the atmosphere. The Study Region
comprises 44% of the land area and 60%-70% of the agricultural
cropland of the conterminous United States.

The figure aggregates study results into a time-line of
agricultural soil carbon (SOC) for a 120-year period,
beginning with conversion of native vegetation to agriculture
in about 1907, through current conditions; three projections
through 2030 are included for different crop yield increases.
Total SOC values for 1990-2030 represent a continuation of
current cropping, rotation, and tillage practices, along with
the impacts of three alternative levels of annual increases in
crop yields--1.5%, 1.0%, 0.5%. These results were obtained by
summing the products of the unit area changes in SOC under
each crop/rotation/tillage combination and the area associated
with each combination within each CD, then summing the values
for all CDs in the Study Region, and dividing by the entire
Study Region area; thus the values are in units of grams C per
square meter (gC/m2) for a 20-cm soil layer.

The historical portion of the curve shows the well-documented
decrease in SOC following land conversion to agriculture in
about 1907, a continuing drop in SOC until 1950, a period of
stable and slightly increasing SOC through 1970, and
significant SOC increases through 2030. These results reflect
increasing crop yields during this period, modeling
assumptions that represent an associated increase in residues
remaining and returning to the soil, and a decrease in the
level and intensity of tillage beginning in 1972.
For the projection period, the increase in SOC is based on the
current mix of cropping and tillage practices, along with
assumed crop yield increases. The curves show steady, almost
linear increases in SOC from 1970-2030. If this general
pattern is accurate, agricultural SOC within the Study Region
made a comeback from a low of about 50% of original native
vegetation levels in 1950-70, to about 60% of these levels by
1990. Continuing the increase would lead to 2030 Total SOC
levels approaching 75% to 90% of the SOC prior to the onset of
agricultural production.

FIGURE 1.


The study concludes that reasonable extrapolation of current
agricultural practices and trends will lead to an increase
(sequestration) of about 1 to 2 Gt C within the Study Region
by the year 2030, or about 25 to 50 Mt C per year. This
represents about a 25% to 50% increase over current 1990
levels. Nationwide the increase could be 50% greater since our
Study Region includes only 60-70% of total U.S. cropland. The
key assumption underlying these predictions is the projection
of annual crop yield increase from 1990 to 2030; the lower
range reflects an increase of 0.5% per year, while the upper
limit of 50% increase reflects a 1.5% per year crop yield
increase. The validity of this assumption needs to be
re-assessed or confirmed, and if valid, policies and research
should be promoted to support the chances of agriculture
attaining these levels of yield increase.


Reference

Donigian, A S, T O Barnwell, Jr, R B Jackson, IV, A S
Patwardhan, K B Weinrich, A L Rowell, RV Chinnaswamy and C V
Cole, Assessment of Alternative Management Practices and
Policies Affecting Soil Carbon in Agroecosystems of the
Central United States, EPA/600/R-94/067, Environmental
Research Laboratory, Athens, GA, April 1994.

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APPLICATIONS OF PALEOCLIMATIC SIMULATIONS AND DATA SYNTHESES TO UNDERSTANDING THE CLIMATE SYSTEM

Patrick J. Bartlein

Department of Geography, University of Oregon
Eugene, OR 97403-1251, USA

The combined use of paleoclimatic simulations and data
syntheses can provide information on the mechanisms and
consequences of global climatic changes. Data syntheses, and
the individual paleoclimatic records they are composed of,
illustrate how climatically sensitive environmental systems,
such as vegetation or lake hydrology, have varied in response
to the large climatic variations of the past. Conceptual and
numerical climate models provide a means for examining the
physical processes that generate these variations. Together,
the simulations and syntheses can provide support for testing
hypotheses about the climate system and for developing a
framework for predicting its future.
The analysis of sequences of simulations and data syntheses
furnish a first-order validation of the general approach of
predicting variations of the climate system over time using
global-scale simulation models. The sequence of data syntheses
and general circulation model simulations assembled in the
COHMAP project, for example, demonstrate that when the
controls or boundary conditions of the climate system are
varied according to their known histories over the past 20,000
years, the observed global- and continental-scale features of
the climate system (as reconstructed from the
paleoenvironmental record) are simulated reasonably well.
Discrepancies between the observations and simulations point
to uncertainties in our understanding of what the past
climatic variations actually were, in the specification of the
boundary conditions, or to inadequacies of the models
themselves. The first source of uncertainty can be minimized
by focusing on robust climatic changes that are recorded by
multiple kinds of evidence, and the second by the retrieval of
the necessary time series of the controlling factors. When
these sources of uncertainty are minimized, mismatches between
simulations and observations point to model inadequacies as
the cause. Instead of being viewed as failures, these
mismatches should be seen as opportunities for further
refinement of the models.
There are several persistent discrepancies between
paleoclimatic simulations and observations that exist, and
jointly hint at the absence of feedback from changes in
vegetation and surface hydrology as the source. Some examples
include the simulation of drier-than-present conditions in the
western United States when extensive pluvial lake systems
prevailed in basins that are now dry; the simulation of
post-glacial warming at high northern latitudes much earlier
than is recorded by the data; and the inability of GCMs to
simulate positive snow and ice mass balances in northern
Canada at times when the observations indicate that ice sheets
began to grow. In each case, the inclusion of feedback from
the changes in vegetation or hydrology that would accompany
the simulated climate changes reduces the mismatch between the
simulations and observations.

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PALEOCLIMATIC CHANGE DURING HOLOCENE PERIOD
OF BENGAL BASIN (CALCUTTA), INDIA

N. C. Barui1 and S. Chanda2

1Department of Botany, Raja Rammohun Roy College,
Nangulpara - 712406, West Bengal, India

2Department of Botany, Bose Institute, 93/1, Acharya Prafully
Chandra Road,
Calcutta - 700009, India

During the Metro Railway Project work a series of sections
were exposed in different parts of Calcutta. The fresh peat
samples were collected from five different locations from
north of Calcutta at various depths reflecting two to three
peat layers sandwiched between sandy clay zones of different
thickness. Some peat samples were also collected at different
locations from the exposed vertical sections of the western
side of the river Hooghly in connection with the brick klins.
The Radio Carbon datings of all the samples at different
depths ranges from 2640 F1 150 YBP to 7030 F1 150 YBP,
confirming the Holocene age of the deposits. The samples were
palynologically investigated. The dominant pollen typesrecovered from the deposits were Heritiera, followed by
Excoecaria Avicennia, Sonneratia, Nipa, Phoenix, Suaeda,
Barringtonia, Bruguiera, Acanthus, etc., most of which were
typical mangroves. Pollen grains of grasses (both wild and
cultivated types) along with some fresh water elements and
fern spores such as Acrostichum, Stenochlaena, were also
recorded in large quantities. The fossil pollen assemblages
indicated the existence of a swampy halophytic vegetation in
the diagrams in and around Calcutta about 7030 years ago from
today, which to some extent express similarities with the
present day vegetation of the Sundarbans the largest mangrove
complex of the world situated about 100 km south of Calcutta.
Fromthe results it may be inferred that the migration of the
forest towards south was probably induced by the continued
river silting, tectonic movement, biotic factors and increased
population.


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A MODELLING SYSTEM FOR ORGANIC CARBON DYNAMICS
IN SOIL PROFILES DURING THE HOLOCENE

P. Becker-Heidmann1, R. Schipmann1, R. Lehfeldt2

1Institut f1r Bodenkunde, Universit4t Hamburg,
Allende-Platz 2, 20146 Hamburg, Germany

2Wasser- und Schiffahrtsdirektion Nord,Hindenburgufer 247, 24106 Kiel, Germany

During the last years, the dynamics of soil organic carbon has
become a major research target also in climate change studies,
because it may help to find the "missing sink" of annually 2
Gt in the global carbon balance. Contrarily to the complexity
of the subject, the modelling approaches have been rather
simple so far. Soil organic carbon is still more or less a
black box in global models.
Our modelling system is based on soil profiles with
distinguished depth and horizon dependent processes and
parameters, accounting not only for decomposition but also for
vertical translocation processes. Main variables are carbon
content, EB13C and 14C age of the soil layers. Output variables
are also carbon, EB13C and 14C of gaseous emissions and
percolation losses to the groundwater. The list of parameters
contains texture (particle size distribution), pH, temperature
and soil moisture and can easily be extended if necessary. The
boundary conditions include EB13C and 14C of the carbon input.
The system is programmed in C++ under Unix operating system
and OSF/Motif with an interactive graphical user interface.
Depth distributions of variables and parameters are visualized
in interactive windows. For sensitivity analysis, the input
data as well as the parameters and boundary conditions can be
modified by drag and drop mouse actions. The system is
designed as a module for a global "Community Terrestrial
Biosphere Model" which will be coupled to a global climate
model, both developed within the common BMBF funded climate
research project "Trace gas cycles". Therefore, all
intermediate modelling are logged into files which can be used
by the other modules.

An extensive data base of thin layer-wise sampled soil
profiles containing carbon, EB13C, 14C age, pH, texture and other
data provides the test data for the different models and
parameter sets. These soils have developed in Northern Germany
after the last glaciation.

ASSESSING VARIABILITY AND TRENDS IN ARCTIC SEA ICE
DISTRIBUTION USING THE SATELLITE DATA

Gennady I. Belchansky, Ilia N. Mordvintsev and Gregory
K.Ovchinnikov

Institute of Ecology and Evolution problems, Russian Academy
of Sciences,
Leninskey prospect 33, Moscow 117071, Russia

Monitoring of the sea ice cover in polar regions is essential
for the understanding of regional and global climate
processes. Results of numerical investigations show that
Arctic sea ice affects the polar climate by regulating the
exchange of heat, moisture, and momentum between the ocean and
atmosphere and is a potential early indicator of global
climate change. A number of studies have suggested that
changes in the global average air temperature might be
detectable by observing changes in the extents of the polar
sea ice covers . One sensitive region in the context of global
change is the Barents-Kara Seas and adjacent parts of the
Arctic Ocean. Documenting variations in the annual minimum ice
extent and concentration is important for establishing
baseline data, for understanding historical periodicity,and
for investigating long-term trends.
However, long-term trends derived from ice maps are fixed
estimates without variance .This report presents some results
of estimating the efficiency of Kosmos-1500, 1766, 1869 and
Okean-1,2,3 polar-orbiting satellite data (RM-08-passive
microwave radiometer, SLR- side-looking radar, and
MSU-M-multispectral optical system) and ALMAZ SAR satellite
data for investigating variability in sea ice distribution in
the Barents Kara seas and adjacent parts of the Arctic Ocean
and documenting variations in annual minimum sea ice extent,
concentration, and comparable analysis of results based on sea
ice database.A combined system takes advantage of different
sensitivities of different sensors to different surface types,
high resolution of SAR data, good temporal resolution and
large scale cover of SLR, RM-08 and MSU-M data. The sea ice
extent was studied for a set sea-ice classification schemes
produced using developed regional-scale remote sensing
database, a multi-thematic geographical database and a
problem-oriented data processing system.Kosmos and Okean
satellite image data were used to estimate confidence
intervals for the 1974-1994 map-derived ice-trends in the
Barents and Kara Seas.Results from the 1974-1993 period were
combined with ice extension data reported by Vinje(1991) to
examine longer-term trends over a 28-year period, 1966-1993.
Trends in the annual minimum sea ice extent determined by
three criteria(absolute annual minimum, minimum monthly-mean,
and the extent at the end of August) were investigated for the
Barents and western Kara Seas and adjacent parts of the Arctic
Ocean during 1966 to 1994. Four definitions of sea ice extent
were examined based on thresholds of ice concentration: > 90%
, >70% , > 40% and > 10% (E1, E2, E3, and E4,
respectively).Trends and sea ice concentration were studied
using ice maps produced by the Russian Hydro-Meteorological
Service (1974-1994) , Kosmos and Okean satellite imagery
(1984-1994), ALMAZ SAR satellite data and data extracted from
published literature. During 1984-1994, an increasing trend in
the extent of minimum sea ice cover was observed in the
Barents, Kara, and combined Barents-Kara Seas, for all ice
extent definitions. Root-mean-square differences between
Hydro-Meteorological sea ice maps and satellite-image sea ice
classifications for coincident areas and dates were 15.5 % ,
19.3 % , 18.8 % , and 11.5 % , for ice extensions E1-E4,
respectively. The differences were subjected to Monte-Carlo
analyses to construct confidence intervals for the 20-year
ice-map trends. With probability p 3D 0.8,the average 20-year
change in the minimum monthly-mean sea ice extent (followed in
brackets by the average change in the absolute annual minimum
ice extent) was between 30-60% [19-71%], 29-61% [15-67 %],
31-63% [18-69%] and 18-48% [7-55%] in the Barents sea;
(-24)-(-4) % [(-25)-(12) %], (-27)-(-9) %
[(-34)-(-4)%],(-32)-(-15)%[(-39)-(-9)%] and (-33)-(-15)%
[(-38)-(-8)%] in the western Kara sea; and (-3)-19%[(-8)-29
%],(-4)-18%[(-11)-26 %], (-6)-16%[(-11)-24)%] and
(-7)-15%[(-12)-24%] in the combined Barents and Kara Seas, for
sea ice concentration E1-E4 respectively. Including published
data from 1966-1983, the trend in minimum monthly-mean sea ice
extent for the combined 28-year period showed an average
increasing of 11.8% in the Barents Sea and of 47.4% reduction
in the western Kara Sea, and sea ice extent at the end of
August showed an average reduction of 4.7% in the Barents Sea.


>>>>>>>>>>>>>>>>>>>>

ALKANES AS GEOMARKERS OF RIVERINE INPUT IN MARINE SEDIMENTS

A.N. Belyaeva

P.P.Shirshov Institute of 0ceanology, Russian Academy of
Sciences
23 Krasikova Street, 117218 Moscow, Russia

New indicative properties of sedimentary n-alkanes in relation
to riverine input were obtained for Russian Arctic Seas and
Amazon river - sea system by means of multivariate statistical
processing ( principal component analysis, cluster and
discriminant analyses) of GC data.

Calculated parameter P which is the linear combination of each
sedimentary alkane content multiplied on weight coefficient
varied from -0.175 in the East Siberian Sea to -0.070 in the
Laptev Sea and to -0.007 in the Chukchi Sea, but it has a
positive value for the Barents Sea ( 0.275). Thus, this
parameter is meaningful for type ranging of Arctic Seas by
bottom sediment alkane composition and provides the advantage
of estimation of unknown interrelations between organic matter
composition and its accumulation conditions in sediments. In
regard of riverine organic matter input to the Arctic bottom
sediments the reversed relation between calculated parameter P
and riverine particulate load is of most importance.

Based on cluster analysis the difference between alkane
composition of the sediments from Amazon River itself and
estuarine sediments was found in the fraction n-C14 - n-C17
which increased from 3-13% in the river sediments to 18-25% in
the estuarine sediments. Since alkane n-c17 is the most
significant component in this fraction such changes could be
induced by increased primary productivity in the river - sea
mixing zone relatively to the river water.

The comparison of alkane composition of North Dvina River and
Amazon River sediments revealed the surprising similarity of
sand sediments of these rivers quite independent from the
different climatic zones. The sands from the both rivers
appeared to be closely situated in the separate cluster which
differed from the clusters of river or estuarine muds by de-

creased content of alkanes C29 - C35. Most probable
explanation of obtained similarity could be significant
differentiation processes of alkanes during sedimentation and
accumulation in sediments. Sorption could play the leading
role in differentiation.
In order to elucidate the significance of sorption process in
the formation of alkane composition of various grain size
sediments 87 alkane spectra of terrigeneous Arctic and
Antarctic shelf sediments were analyzed by discriminant
analysis. The results of this study evidenced that the grain
size and bulk organic carbon content of sediments are of
primary importance for sorption which is markedly influence on
alkane composition.

In conclusion, sedimentary alkane composition contains
information on the main source input which could be revealed
on the basis of interrelationship between alkane constituent
rather than separate biomarker alkanes. Moreover, the
quantitative parameters obtained by multivariate statistics
seems to be the means for assessment of riverine particulate
load to marine sediments and so they could be useful for
attributing sediments from modern estuarine areas and
paleodelta environment.

>>>>>>>>>>>>>>>>>>>>

INTERACTION BETWEEN POLAR ENVIRONMENT AND SOURCE-SPECIFIC
SEDIMENTARY LIPIDS IN THE KARA SEA

A.N. Belyaeva1, G. Eglinton2

1P.P. Shirshov Institute of Oceanology,
RAS23 Krasikova Street, 117218 Moscow, Russia

2University of Bristol Cantock's Close, Bristol BS8 1TS, UK

In order to study the influence of polar environmental
controlling factors onto accumulation of source-specific
lipids in the bottom sediments 15 samples on the transect from
the Ob River mouth to the northern part of the Kara Sea have
been analyzed for molecular lipid composition. Since the Kara
Sea is distinguished from other Arctic Seas by the most inten-

sive riverine runoff (about 1350 km3 per year) terrestrial
derived lipids predominate over autochtonous ones in alkane,
fatty acid and fatty alcohol patterns. However, terrestrial
imprint as well as the spatial distribution of lipids of
primary plankton or bacterial origin in sediments are not
uniform along the transect. The relative importance of various
source lipids in the surface sediments appeared to be related
to sedimentation process rather than to variations in primary
productivity or to the distance from the Ob River. Therefore,
high terrestrial signal in sedimentary lipids in the river -
sea mixing zone is correspondent to high organic carbon flux
measured by means of sedimentary traps (Lisitzyn et al.,
1994). Maximum accumulation of plankton derived lipids in
surface sediments has been found in the area of low primary
productivity but it was closely related to the highest flux of
autochtonous detritus produced preferentially by zooplankton
(Lebedeva, Shushkina, 1994).

The importance of bacterial organic matter transformation in
the polar organic carbon cycle is still open for discussion.
On the basis of tentative calculations of organic carbon cycle
in the Barents Sea (Belyaeva et al., 1989) the reduced rate of
organic matter degradation in the water column and surface
sediments resulted from low bacterial activity. The low
bacterial biomass in the Kara Sea water (up to ten mg per m3)
(Mitskevich, Namsaraev, 1994) seems to confirm the hypothesis
of low bacterial activity in the polar environment. However,
bacterial derived fatty acids averaged at 9.5% of total acids
in the Kara Sea sediments and that value is of the same range
as corresponding values for the southern Bohai Sea (Bigot et
al., 1989).The enhanced bacterial imprint has been registered
near the Ob River mouth similarly to high bacterial lipid
content of the Lena River estuary (Laptev Sea) (Peulve et al.,
1993). Bacterial fingerprint in the Kara Sea sediments was
supported also by alkane patterns. These data evidenced that
Arctic estuarine areas are distinguished by intensive
bacterial organic matter transformation and the overall
distribution of bacterial sedimentary lipids is not suppressed
in the Kara sea in relation to low environmental temperature.
Of notice is the fact that accumulation of bacterial lipids in
sediments does not reflect the bacterial cell number in the
water column but it seems to be resulted in the activity of
more abundant bacteria associated with the surface of
particulate matter (Lisitzyn et al., 1994).

In conclusion, the accumulation of source-specific lipids in
the Kara Sea sediments is controlled by two main environmental
factors including the terrestrial organic matter input and by
biogenic heterotrophic processes that incorporate zooplankton
and bacteria activity. The significance of phytoplankton
organic matter input is decreased relatively to the next stage
of trophic chain.

>>>>>>>>>>>>>>>>>>>>

APPLICATION OF MULTIFRACTAL ANALYSIS
TO INTERPRETATION OF SEDIMENTARY LIPID PATTERNS

A.N.Belyaeva, S.S. Ivanov

Institute of Oceanology, RAS,
23, Krasikova Str., 117218, Moscow,Russia

The objective of the presented approach is to obtain a few
number of general parameters characterizing the GS-MS
chromatogram of sedimentary lipids instead of several hundreds
of values of concentrations of recorded individual components.
Multifractal analysis allows to emphasize the influence of
minor recorded peaks and obtain intrinsic regularities
governing the distribution that are hardly seen in the
original data.
We studied fifteen GC-MS spectra of bottom sediment samples
from the Kara Sea. Concentrations Ci were regarded as a
probabilistic measure distributed over a set of components.
For each moment q of distribution scaling exponent tau(q) and
dimension D(q) were computed, describing multifractal scaling
behavior. D(0) gives geometric dimension of the supporting set
(in our case D(0)3D1), D(1) presents the informational
dimension of the measure itself, and the correlation dimension
D(2) defines scaling propertie s of the squared values. These
three dimensions give much for understanding of internal
structure of the measure and degree of its multifractality.
Legendre transform allows to pass from (tau-q) coordinates to
(f-alpha) system and construct function f(alpha), indicating
singularities of initial data.
We have found the correlation between different fractal and
multifractal parameters of lipid spectra of bottom sediments
along the transect from the Ob River mouth to the north of the
Kara Sea. These data appear to be closely related to
sedimentary organic matter genesis analysed by means of
biomarkers of plankton and terrestrial primary origin. For
example, decrease of informational dimension consistent with
the increased accumulation of plankton derived organic matter
in sediments was definitely stated. In contrast, the increased
input of terrestrial organic matter leads to opposite changes.
Moreover, we obtained a number of additional evidences of
interrelation of fractal parameters with other indicative
lipid constituents promising for detection of diagenetic
organic matter transformation. These results could be applied
for various geochemical problems and, in particular, for
assessment of various sources and mechanisms of organic matter
preservation and accumulation in marine environment.


>>>>>>>>>>>>>>>>>>>>

VERTICAL EXCHANGE AND REDFIELD RATIOS
ALONG NEUTRAL SURFACES

J. Bendtsen1 and G. Shaffer1,2

1Department of Geophysics, Niels Bohr Institute for
Astronomy,
Physics and Geophysics, University of Copenhagen,
Haraldsgade
6,
2200 Copenhagen N, Denmark

2Born Institute for Ocean and Climate Studies, Holma
4235,
45400 Brastad, Sweden

Vertical transport of a tracer due to small scale turbulence
and associated diapychnal advection can be estimated from the
vertical curvature of potential temperature, salinity and the
tracer. Vertical transports calculated this way can be
projected upon and averaged along neutral surfaces (neutral
surfaces are those surfaces in the ocean interior along which
lateral mixing takes place preferentially). Such mean
transports can be used to correct estimates of
remineralization ratios obtained calculated by analysis of
ocean chemical data projected along neutral surfaces (eg
Anderson and Sarmiento 1994). Traditionally, vertical exchange
has been assumed to be negligable in such analyses.
Our method has been applied to GEOSECS data from the South
Atlantic, Indian and tropical Pacific oceans. When the
correction for vertical exchange is included, estimates of
-O2:P remineralization ratios in the upper part of the main
ocean thermocline turn out to be significantly lower than
those of the traditional method.
References:
Anderson L. A. And J. L. Sarmiento (1994) "Redfield ratios of
reminaralization determined by nutrient data analysis", Global
Biogeochemical cycles, vol 8, No 1, 65 - 80.

>>>>>>>>>>>>>>>>>>>>

The physical climate subsystem and climate change.

Lennart Bengtsson
Max Planck Institute for Meteorology
Bundesstrasse 55
D-20146 Hamburg

Abstract.

The climate system constitutes a complex interaction between the atmosphere, the oceans an the land surfaces and incorporates physical, chemical and biological aspects. On shorter time scales the climate system is essentially controlled by physical and dynamical processes, which in its principal form has been known since the end of the last century. Our empirical knowledge of the system though, with the exception perhaps of the atmosphere, is still rather poor and massive observational improvements are certainly required. Nevertheless, significant improvements are being made and it has been possible to study the coupled atmospheric/ocean system in reasonable details, in spite of the great difficulties to describe the sources and sinks of energy, momentum and water vapour in terms of the resolvable variables, as well as having the computational capabilities to numerically do this with a realistic accuracy.

The lecture will describe where we stand at the moment, illustrate some of the many achievements and discuss some of key issues which presently are pursued by the scientists. Examples of such issues are to better understand the predictability of the climate system, the problem of coupling the fast climate components, such as the atmospheric, with time scales of days and weeks, with the much slower ocean processes with time scales streching beyond decades and centuries.

Presently, intense work is going on within the framework of climate change, to couple the physical part of the climate system to the chemical aspect of the system, and to incorporate into this, the interaction with the biospheric processes at land and in the sea. The close scientific interaction between previously largely separated scientific groups has not only created a sound foundation for a joint scientific program for climate change, but also provided important techniques for model improvements, such as the calculation of chemical tracers for the measurement of the the exchange processes in the atmosphere, the land and in the oceans and between these media.

>>>>>>>>>>>>>>>>>>>>

THE UK TIGER PROGRAMME - NATIONAL THINKING AND GLOBAL MODELLING

M. Beran

TIGER Programme Office, Wallingford, UK

TIGER (Terrestrial Initiative in Global Environmental
Research) provides the major focus in the UK for research into
the many ways in which the land surface is implicated in earth
system processes in general and climate change processes in
particular. Around 300 scientists in over 100 projects direct
their research towards problems of carbon cycling, trace
greenhouse gases, the energy and water budget, and impacts on
ecosystems.

Within each of these four components of the TIGER programme
one finds a hierarchy of research building from process
studies in the laboratory, through field observations, up to
modelling at landscape, continental and global scales. This
paper reports on recent findings of the programme with a
particular focus on those large-scale activities closest to
the concerns of GAIM. These include carbon cycle models at
regional and global scales, a contribution to a global trace
gas transport model, continental scale hydrological models,
and descriptions of regional ecosystem and global vegetation
models. In each case these have been formulated to accomodate
future climate and CO2 changes, and in some cases also
incorporate parallel land cover changes forced by man's other
activities.


>>>>>>>>>>>>>>>>>>>>

SIMULATING CLIMATE/VEGETATION FEEDBACK:
AN INVESTIGATION OF THE EFFECTS OF
VEGETATION CHANGE ON A DOUBLED-CO2 CLIMATE

R. A. Betts1, P. M. Cox1 and F. I. Woodward2

1Hadley Centre for Climate Prediction and
Research,
UK Meteorological Office, Bracknell,
Berkshire RG12 2SY, UK

2Department of Animal and Plant Sciences,
University of Sheffield,
Sheffield S10 2TN, UK

Vegetation has a major effect on the fluxes of radiation,
sensible heat, moisture, momentum and biogeochemicals between
the atmosphere and the surface; it therefore has an important
influence on climate. Since the distribution of different
forms of vegetation is largely determined by climate, it
follows that changes in vegetation may act as a feedback
mechanism in the processes of climate change.
At present, most General Circulation Model (GCM) simulations
of climate change have not yet included vegetation feedback,
since they contain fixed representations of land surface
properties. The aim of the work described in this paper is to
make make a quantitative study of this feedback, using the
Hadley Centre GCM asynchronously coupled with the Sheffield
University Dynamic Global Vegetation Model (DGVM). The DGVM
predicts global vegetation in terms of Leaf Area Index (LAI),
Net Primary Productivity (NPP) and stomatal conductance, in
response to climate data provided by a GCM simulation with CO2
at a constant level. The three quantities predicted by the
DGVM can then be used to derive the vegetation characteristics
required as parameters in a further equilibrium GCM
simulation. This process can be repeated until the iterations
cause no further change, to give the equilibrium vegetation.
This paper describes the use of this method to simulate the
effects of vegetation feedback on climate change induced by a
doubling of CO2. The above procedure is carried out with a
doubled-CO2 GCM, starting with the vegetation predicted by the
DGVM for present-day conditions. The difference between the
first and last of the GCM climates can then be interpreted as
the contribution of the vegetation feedback to the climate
change due to doubling CO2. This result will be presented
here.

>>>>>>>>>>>>>>>>>>>>

RECORD ON THE CHANGE OF HOLOCENE CLIMATE IN THE LATERITIC
ZONES OF WEST BENGAL, INDIA BY POLLEN ANALYSIS

K. Bhattachaya

Department of Botany, Visva Bharati University
Santiniketan. 731 235.. INDIA.


Pollen analytical investigations to trace Holocene
vegetational history and climate of the lateritic zones of
West Bengal, India have been made. Judging from the above
study it reveals that natural forest constituents of tropical
broad-leaved elements existed in all parts of the area during
Holocene period. The main components of the vegetation are
comprised of the elements like
Shorea-Madhuca-Buchanania-Terminlia along with some other
tropical elements. The uniformity in distribution of
non-arboreals between the Holocene and present day vegetation
may be due to their high adaptive value. Palynological
application of Hierarchical cluster analysis of 16 sub-surface
samples also provide informations regarding past vegetational
environment. Two dendograms have been plotted for arboreal and
non-arboreal dendogram pollen taxa. From the arboreal
dendogram it is established that Shorea and Terminalia show
highest positive correlation in the minimum distance of 0.70.
When the distance increases upto 0.74 there is an association
of Shorea, Terminalia, Anacardium and Buchanaria. Among
non-arboreals Acanthaceae, Scrophu- lariceae and Polygonum are
in one cluster with a minimum distance value of zero. From the
above study it is evident that the association of tropical
broad-leaved elements still persists in some restricted parts
of the investigated area. The above elements perhaps got
extinct from most parts due to biotic interference and other
ecological factors.

>>>>>>>>>>>>>>>>>>>>

MODERN ANTHROPOGENIC INFLUENCE
ON GLOBAL CHANGE OF Si CYCLE

E.Bocharnicova, V.Matichenkov

Institute of Soil Science and Photosynthesis RAS, 142292,
Pushchino, Russia

Si is of a primary importance for plants and microorganism.
Without thes element the growth of plant impossible. The
silicon concentration in the ocean limits the plankton
population. Human activity results in a change in the natural
element cycling by removing elements and modification of
moving sense. The soil-plant system is base for the main
terrestrial trophic chains. It is precisely in soil, a great
amount of silicon is involved into biological circulation. A
main negative influence of human activity on the silicon cycle
and natural balance is observed in the soil-plant system. An
estimated 27.5 million tons of Si are removed with crop
harvest (by comparison, 18 million tons of P is "harvested").
Different cultures very in Si accumulation and removal. Our
calculations and literature data showed that the with each
harvest from 20 to 250 kg of Si ha-1 may move from the soil.
For example, about 100 kg of Si ha-1 is taken up by sugarcane
and as many as 250 kgof Si ha-1 by rice.
Plants adsorb silicon only in low molecular form (monosilicic
acid). But monosilicic acids amount in the soil is usually
small usually (from 1 to 200 kg Si ha-1 in the upper horizon).
Consequently, crop-bearing soils have a negative balance of
mobile silicon compounds and plants may exhibit in short Si
supply. Silicon deficient in the soils results in destroing
soil minerals to supplement plant-available Si. That destroys
silicon equilibrium in the soil and has negative consequences
namely increased susceptibility of plants to disease and
insects attacs, changes in plant elemental composition,
worsing physical-chemical soil properties - cementation,
increased of soil density, decreased soil ability to adsorb
nutrients and water. An estimated 9,0 million tons of Si are
removed from natural cycle annualy when forests are cut down.
All this silicon is irreversibky lost for the soil-plant
system.
Another global change of the silicon cycle by human activity
is connected with mining and concentration of ore. World
industry involves 1011 tons of rock minerals every year which
contain only 1% of ore and 40 to 80% of SiO2. A great part of
metal industry wastes is presented by various silicates which
aren't utilized today. Many of these wastes don't contain any
pollutant substances but they occupy a great area. By this
means human activity interfer with the nature silicon cycle
and silicon substabce is increasing every year. It is
necessary the silicon factor to be included in various models
and data incomparison, because the change of silicon status in
the soil-plant system has a great impact on plant
productivity, geochemical and biogeochemical reactions in soil
and natural waters. Silicon problem is not taken into account
numerouse errors in biogeochemical model simulations and
management of natural resources are possible.

>>>>>>>>>>>>>>>>>>>>

BIOGEOGRAPHIC AND CLIMATIC EVOLUTION OF THE COASTAL PLAIN
OF THE GULF OF BENIN FROM THE PLEISTOCENE TO THE
SUBACTUAL ERAS (WEST AFRICA)

M. Boko

Laboratoire de Climatologie UNB/DGAT,
BP 03-1122, Cotonou, Benin


The fringing coastal of Benin is one of the regions of West
Africa of which the dynamics during the Quaternary and the
Subactual Eras is marked by the major climatic and biogeo-

graphic events.

Thanks to many sediments facies allow to reconstitute this
evolution .

Although divarications exist yet about the agreement between
the dynamics of the regional paleoenvironments and the well
known events of global scale (glaciations and interglacial
ages), we may retain some fundamental facts.

FromInchirian Age to Tafolian Age (35,00 to 2,00 BP), humid
and dry phrases occurred by returns, in variable duration,
corresponding respectively to transgressions and recessions of
sea.

Coastal sand ridges have been formed during the last part of
the Tafolian Age, after the sea retreat which had uncovered
the coastal plain and stretched the course of coastal rivers.
This period marked the settlement of the first stands of the
mangrove vegetation (3,700 to 2,600 BP), the apparition of oilpalm tree (2,800 BP) and stands of Lophira lanceolata (2,500
to 1,400 BP).

The first traces of human activity had appeared belatedly in
the form of accumulations of shells (1,070 BP).

A slight sea recession occurred between 400 and 300 BP (1,500
A.D.) and provoked the disappearing of the mangrove vegetation
and the apparition of fresh water swampy forests round the
pre-coastal lakes deprived of sea water.

This evolution may explain the current dynamics of the coastal
zone of the Gulf of Benin, mainly the hydrologic continent-
ocean exchanges, and its biogeographic aspects.

Key-Words: West Africa, Gulf of Benin, paleoenvironment,
trangession, recession, sand ridges, mangrove,
lakes, swampy forests.


>>>>>>>>>>>>>>>>>>>>

BIOTIC AND ABIOTIC FACTORS OF THE CARBON SYSTEM
COMPONENTS VARIABILITY IN THE NORTH ATLANTIC

P. V. Boubnov

Institute of Oceanology of Russian Academy of
Sciences,
Laboratory of Biochemistry and Hydrochemistry,
24 Krasikova Street, Moscow, 117851, Russia

The problem of the carbon cycle in the ocean is now one of the
most actual problems of modern oceanography. This is connected
with the permanent increase of the CO2 concentration in the
atmosphere, caused by industrial activity, which can exert
significant effect on global climate. Maps of the inorganic
carbon forms distribution in the upper layer of the North
Atlantic, based on analysis of big massive of hydrochemical
data, were built to show reguliarities of the carbon cycle in
the North Atlantic. Two principal factor groups of the
inorganic carbon forms distribution were singled out: biotic
and abiotic. The most significant abiotic factor is the
temperature changes. Production and destruction of the organic
matter are the principal biotic factors. The variabilities of
the CO2 and total inorganic carbon due to the temperature
changes were calculated. The differences between the real and
temperature variabilities of the CO2 and total inorganic
carbon
can be interpreted reliably as the biotic factors effect.
Variability values, caused by biotic factors are in good
agreement with the primary production in the upper layer. The
values of the biotic CO2 variability are 0.02-0.04 gC/m3 year
in the central part of the North Atlantic, increasing up to
0.07-0.08 gC/m3 year near Africa and South America shores and
reaching 0.10-0.15 gC/m3 year in areas of high primary
production near Island and Greenland shores. The maximum
biotic CO2 variability - 0.2 gC/m3 year is observed near the
bank of Newfoundland. The primary production values exceed the
in-year CO2 variability, caused by biotic factors 5-15 times
in
average. It is due to the CO2 ocean-atmosphere exchange and
vertical movement of water masses. The values of biotic
variability of the total inorganic carbon exceed the primary
production values, because the total inorganic car- bon is
included in other biochemical processes. Maps of the CO2 and
Ctot. variabilities make possible to show areas with different
biochemical activity in the ocean.

>>>>>>>>>>>>>>>>>>>>

INFERRED SOURCES AND SINKS OF CO2 USING
2-D AND 3-D ATMOSPHERIC TRANSPORT MODEL
P.Bousquet1, P.Ciais2, M.Ramonet1, P.Monfray1, Y.Balkanski2

1Centre des Faibles Radioactivits, Laboratoire mixte
CNRS-CEA,
B3timent 709/LMCE, CESaclay, 91191 Gif-sur-Yvette Cdex,
France.

2Laboratoire de Modlisation du Climat et de l'Environnement,CE Saclay, B3timent 709, 91191 Gif-sur-Yvette Cdex, France.

Owing to atmospheric sampling network, modeling spatial and
temporal variations of CO2 in the atmosphere is a valuable
approach to describe the distribution of the surface fluxes.
However, modeled atmospheric transport is a potentially
important source of uncertainty in the diagnostic of the CO2
sources in sinks.

CO2 and Carbon-13 measurements from 50 sites of the NOAA/CMDL
global air sampling network and from the CSIRO network were
used as an input for a 2-D model of atmospheric transport a,b
(CMDL, Boulder), run in an inverse mode. The information given
by carbon-13 lead to partition oceanic and terrestrial CO2
fluxes, in 20 latitude bands b. In order to estimate how
sensitive this result is to atmospheric transport, we have
used the net fluxes predicted by the 2-D study as an input of
a 3-D atmospheric transport model c (MPIM, Hambourg). The 3-D
concentration fields of CO2 simulated in that manner are then
inverted again with the 2-D model. Differences between both
sets of fluxes reflect distinct transport features between the
two models, that we further analyse here.

Using the 3-D transport model, we found no significant
difference in the amplitude of the strong northern-mid
latitude terrestrial sink as predicted by the 2-D analysisb
(3.5 11.8 GTC for 1992). However, there are differences in
meridional transport across the ITCZ, which we quantify in
terms of CO2 fluxes. Also we employed two sets of input fluxes
for the 3-D model: one partionned between land and ocean and a
second which is zonally distributed. We discuss the
sensibility of North/South gradient predicted by the 3-D model
to these two longitudinal distributions.

a. Tans, P., T.J. Conway, and T. Nakazawa, Latitudinal
distribution of sources and sinks of atmospheric carbon
dioxyde derived from surface observations and an atmospheric
transport model. Journal of Geophysical Research, 1989, 94.

b. Ciais, P., et al, Partitioning of ocean and land global
uptake of CO2 as inferred by deltaC13 measurements from the
NOAA/CMDL global air sampling network. Journal of Geophysical
Research, 1994, 100.

c. Heimann, M., and C.D. Keeling, A three dimensional model of
atmospheric CO2 transport based on observed winds: 2. Model
description and simulated tracer experiments, In Aspects of
Climate Variability in the Pacific and Western Americas,
edited by D.H. Peterson, American Geophysical Union,
Washington DC, 1989.


>>>>>>>>>>>>>>>>>>>>

CLIMATIC CHANGES IN BULGARIA DURING THIS CENTURY

T.G. Boyadjiev
Bulgarian Society for Soil Science,
Zona B5, Blok 3, ap. 44, 1303 Sofia, Bulgaria
The change of climate in Sofia has been observed and recorded during this century. Temperature data for the period from 1887 to 1930 were compared with these of the period from 1931 to 1970 (for the precipitation data the latter period is from 1931 to 1985). Changes of maximum temperature values were observed and recorded during the mentioned periods.

It was found out that temperature had risen averagely by 0.5C per year and warming up has been better manifested during the autumn and winter months than spring and summer ones. Weather warming has been accompanied by slight drought (15 mm average annual for the period), especially in August, September and October.

Absolute temperature peaks vary in wide range between the two periods (up to 11 - 12.7C), while the average minimum and maximum temperature differences are insignificant (up to 1.6C).

The following zones can be differentiated on the territory of Bulgaria depending on the temperature changes in the period from 1931 to 1970 compared with the ones between 1887 and 1930:

- zone in which the temperature for the period from 1931 to 1970 is higher than the temperature between 1887 and 1930 and this temperature rise includes all months (Sofia);

- zone in which for the former time range the temperature rose in winter and spring months and dropped in summer and autumn (Karnobat, Vratza);

- zone in which temperature rose in winter and dropped in the remaining months (Tzarevo, Stara Zagora, Pleven);

- zone in which the temperature during the 1931-1970 period was lower than the 1887-1970 period and this temperature decline includes all months (Lom, Chepelare).

TSSI (Temperature Stress Severity Index), MSSI (Moisture Stress Severity Index) and CSSI (Climate Stress Severity Index) were computed at representative weather forecast stations in these zones, as well as the duration of the vegetation period. F. Newal mathematical model was used for this purpose. It is applied in defining water thermal soil regimes in the American soil taxonomy system.

>>>>>>>>>>>>>>>>>>>>

ABSTRACT

Oceanic radiocarbon: Separation of the natural and bomb components
Wallace S. Broecker, Stewart Sutherland, and William Smethie
Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York

Tsung-Hung Peng1
Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge,
Tennessee

Gote Ostlund
Institute of Marine Science, Rosenstiel School of Marine and Atmospheric
Sciences, University of Miami, Miami, Florida

Abstract. An improved method has been developed for the separation of the
natural and bomb components of the radiocarbon in the ocean. The
improvement involves the use of a very strong correlation between natural
radiocarbon and dissolved silica. This method is applied to radiocarbon
measurements made on samples collected during the Geochemical Ocean
Sections Study (GEOSECS), Transient Tracers in the Ocean (TTO) and South
Atlantic Ventilation Experiment (SAVE) expeditions. On the basis of this
new separation we provide not only an estimate of the global inventory of
bomb 14C at the time of the GEOSECS survey but also the distribution of
bomb radiocarbon along four thermocline isopycnals in each ocean. We also
document the evolution of the bomb 14C inventory and penetration along
thermocline isopycnals in the North Atlantic Ocean between the times of the
GEOSECS (1972-1973) and TTO (1980-1982) surveys and in the South Atlantic
Ocean between the times of the GEOSECS (1973) and SAVE (1987-1989) surveys.
In addition, we show that the bomb tritium to bomb 14C ratio (expressed in
the tritium unit (TU) 81 units/100 ) for waters entering the thermocline of
the northern hemisphere is about 9 times higher than for those entering the
southern hemisphere thermocline. This contrast offers long-term potential
as an indicator of inter-hemispheric transport of upper ocean waters.


>>>>>>>>>>>>>>>>>>>>

DEFINING THE OCEANIC TRANSITION ZONE

C. W. Brown and W. E. Esaias

NASA/Goddard Space Flight Center Oceans and Ice Branch,
Code 971 Greenbelt, MD, 20771, USA

One proposed technique to calculate oceanic primary
productivity from satellite-derived estimates of phytoplankton
biomass requires that the oceans be divided into
biogeographical zones, each with its own unique physiological
characteristics. The oceanic Transition Zone, a region located
between the oligotrophic subtropical gyres and the eutrophic
subpolar gyres, represents a distinct biogeographical regime.
The criteria used to define the geographic limits of the
Transition Zone will determine its spatial extent and
consequently impact the estimates of global primary
productivity. Defining the boundaries of the Transition Zone
will also provide a means to track its position over time and
ascertain the seasonal and interanual variability of the
location of this important ecotone. However, no definitive
criteria exists to identify the boundaries of the Transition
Zone from a biological perspective.

We evaluated several methods and criteria to delimit oceanic
Transition Zones. The Transition Zone of the Atlantic and
Pacific Oceans were located by identifying discontinuities in
the meridional distribution of CZCS pigment concentrations and
AVHRR sea-surface temperatures in monthly composites. Gradient
analysis, the moving split-window technique, and
autocorrelation were applied to the imagery. Threshold values
were selected and the areal extent of the Transition Zones
resulting from several criteria applied to each method were
compared over an average annual cycle.

>>>>>>>>>>>>>>>>>>>>

MIXED LAYER PULSE RESPONSE FUNCTION AND
OCEANIC TRACER UPTAKE

M. Bruno, F. Joos

Climate and Environmental Physics, Physical Institute,
University of Bern, SidlerstraE1e 5, CH-3012 Bern, Switzerland

Program in Atmospheric and Oceanic Sciences, Princeton
University,
Princeton, NJ, USA


Text nur auf Papier (LaTex)


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ABSORPTION OF ANTHROPOGENIC 12C, 13C AND 14C
BY THE OCEAN: AN OCEAN GCM SIMULATION

K. Caldeira1, P. B. Duffy1 and G. H. Rau1,2

1Global Climate Research Division, Lawrence
Livermore
National Laboratory, 7000 East Ave., Livermore, CA
94550, USA

2Institute of Marine Sciences, University of Santa
Cruz, CA
95064, USA

We have developed an inorganic carbon cycle model that
computes steady-state concentrations of total inorganic 12C,
13C
and 14C. This model is based on a detailed calculation of the
speciation of total dissolved inorganic carbon and the
fractionation of carbon isotopes that occur during air-sea gas
exchange. Furthermore, we are now developing an ocean carbon
cycle model that incorporates biological transport of carbon
and carbon isotopes. These models are coupled to a version of
the GFDL ocean general circulation model that incorporates (1)
a dynamic sea-ice model and (2) the Gent-McWilliams
parameterization for the impact of isopycnal eddies on
advection and diffusion in the ocean.
We will present results of our three-dimensional simulations
of the penetration of anthropogenic carbon, and carbon
isotopes, into the ocean, from pre-industrial times, through
the bomb era, to the present. Our calculations produce
three-dimensional fields for the perturbation to 12C, 13C and
14C
concentrations as a function of time. We will present results
from our inorganic carbon cycle model. If available, we will
also present results from our organic carbon cycle model.
These calculations are directly relevant to the estimation of
oceanic CO2 absorption.
Measurement and modeling of oceanic [#183#CO2], 13C/12C and
14C/12C may serve to narrow uncertainties in predicted oceanic
absorption of anthropogenic CO2. Furthermore, the ability to
predict and simulate the penetration of the fossil-fuel carbon
and bomb 14C into the oceans are potential tests of ocean
general circulation and carbon cycle models. Such model
results should be useful in helping to guide measurement
efforts, as measurement efforts could be focused where models
suggest the signal should be strongest.
This work was performed under the auspices of the U.S.
Department of Energy by the Lawrence Livermore National
Laboratory under Contract No. W-7405-Eng-48.

>>>>>>>>>>>>>>>>>>>>

A STATISTICAL APPROACH TO SCALING BIOGEOCHEMICAL
FLUXES IN THE OCEAN USING SATELLITE DATA

J. W. Campbell, G. M. Weiss, and S. R. Gaudreau
Ocean Process Analysis Laboratory
Institute for the Study of Earth, Oceans, and Space
and Department of Earth Sciences
University of New Hampshire
Durham, New Hampshire 03824, USA
Satellite remote sensing measurements will play a key role in
scaling biogeochemical fluxes to the global ocean. The spatial
resolution of many ocean satellite sensors lies between that
of global-scale models and local-scale measurements used to
parameterize models. Global-scale models typically have
resolution elements on the order of 1-4 degrees in latitude
and longitude (100-500 km spatial resolution). Processes
within the models are often parameterized with in-situ data
collected at much smaller scales (e.g., point measurements
made from a ship or time series data at a mooring).
Small-scale measurements, however, cannot be scaled up readily
to obtain large-scale average properties. This is largely a
consequence of the high small-scale variance and nonlinear
nature of ecological and biogeochemical processes in the
ocean. The use of spatial means as input in nonlinear models
does not result in the mean of the modeled property. In order
to represent these processes in global Earth systems models,
one must properly account for variability at scales ranging
from the local to the global.
In this paper, we will demonstrate how statistical information
potentially derived from satellite measurements is needed to
properly extend local-scale flux equations to global and
annual scales. By way of illustration, we will focus
specifically on the flux of CO2 between the ocean and
atmosphere to demonstrate how certain statistical facts and
artifacts might lead to significant underestimation of the
carbon flux. Undersampling leads to underestimation when the
variables being sampled are highly skewed (a statistical
fact). Spatial and temporal variability in nonlinear
biological and physical processes, if not properly modeled,
can bias model results (a statistical artifact). A statistical
approach is needed to account for the effects of the
small-scale variance in scaling local models to the global
scale.
We will describe a statistical approach based on results of
our NASA-sponsored research for the past 3 years. In this
work, we have studied spatial and temporal patterns of
variability in phytoplankton pigments, photosynthetic rates,
and ocean optical properties, and have recommended methods for
averaging satellite data over spatial scales of order 10-100
km. The methods we have recommended will help avoid problems
associated with scale. By knowing statistical properties of
the sub-scale variability, one can predict large-scale spatial
means of derived fluxes. Specific examples will be presented
to illustrate how the spatial distributions of phytoplankton
pigment concentration, surface photosynthetic available
radiation, mixedlayer temperature, and wind speed, all derived
from satellite measurements, are required to scale models of
biogenic carbon flux to the world's ocean.

>>>>>>>>>>>>>>>>>>>>

INTEGRATIVE MONSOON DYNAMICS

P. Carl

Institute of Physics, Humboldt University
Hausvogteiplatz 5-7, D-10117 Berlin, Germany

Regional climate and environmental change dynamics are
accessible with sufficient certainty only in a global context.
Their long-term comprehension appears to be crucially
dependant upon the existence and safe identification of
dynamic regimes of operation of the Earth system. The climate
subsystem offers natural oscillators which fundamentally
contribute in shaping respective global `architectures'.
Monsoon dynamics, with its sensitive but dynamically stable
`active-break' cycles, rises to fame as such an oscillator -
perhaps the most important natural one. Critical transitions
between climate regimes of different functionality are
essential to a `monsoon hypothesis' derived in connection with
a first comprehensive in-depth analysis of the dynamic system
of a General Circulation Model (GCM).
Deliberate use is being made of a very economic, coarse
resolution (12 lat x 15 lon) two-layer tropospheric GCM which
turned out to be a kind of `regime model' in that it
accentuates the low-dimensional character of the global
system`s dynamics. Thrown into relief against the seasonal
cycle by bifurcations, an oscillatory monsoon regime at the
30-60 days timescale develops for both summer and winter.
Detailed studies are concerned with the GCM`s summer monsoon
attractor which is organized as an interhemispheric coupled
oscillator phenomenon, apparently at the highest possible
coupling strength. Tropical/extratropical interactions carried
by shifts and intensity changes of the major tropospheric jets
(`jet shifting oscillator' - JSO) are inherent to this strong
coupling. The dynamics born in this architecture of the
model`s monsoon system enables it to simulate both large Asian
precipitation systems and midlatitude intraseasonal
temperature and precipitation profiles at least qualitatively
correct.

It is important to note that `climate change' events detected
on the intraseasonal attractors of the model`s summer monsoon
are found to be accompanied by common spectral shifts, of the
(four) coupled oscillators, which preserve their rational
frequency relationships. As far as the model climate is
concerned, influences external to atmospheric dynamics
encounter these selection rules and come into effect if they
are capable of triggering such a common oscillator shift.
After decoupling (and extinction) of the JSO at monsoon
retreat, the (atmospheric!) model exhibits a Southern
Oscillation (SO) attractor at a much lower coupling strength.
This might explain the greater irregularity of the SO, as
compared with the monsoon activity cycle. Timescales of
relevance to ENSO found in seasonal simulations using the same
model include both a quasi-biennal oscillation (QBO) and a
longer term modulation of about 6.2 years. Specific monsoon
retreat trajectories are blamed for phase locking of ENSO to
the annual cycle.
The systems analytic interpretation of a GCM`s phase space
trajectories supports an approach to global change via climate
analogs. An integrative, universal response of the model`s
monsoons to different forcings, grasped with the term degree
of monsoon excitation, is found to link regional to global as
well as intraseasonal to palaeoclimatic scales. A `monsoon
climate' bifurcation is encountered if the (intraseasonal)
onset and retreat bifurcations merge at some critical forcing.
The study illustrates the potential of monsoon dynamics both
to trigger abrupt climate change and to cause long-term
instability of the planetary-scale hydrological cycle.
`Survival' of Mei-Yu and/or (non phase-locked) ENSO regimes
after loss of the oscillatory, interactive monsoon climate are
fundamental to the latter aspect of past global climate
change.

GREENLAND AND ANTARCTIC CH4 RECORDS AND THEIR IMPLICATIONSWITH PAST CLIMATIC CHANGES

J. Chappellaz and D. Raynaud

CNRS Laboratoire de Glaciologie et Gophysique de
l'Environnement
BP 96, 38402 St Martin d'HAres Cedex, FRANCE

This presentation aims to discuss the state of the art of
methane measurements from both Greenland and Antarctic ice
cores, in terms of information on the CH4 cycle, past climatic
changes and phase relationship between climatic parameters
obtained from ice cores.

Methane, as a radiatively active trace gas, is of large
interest for the understanding of past climatic conditions.
During the most recent years, increasingly detailed profiles
of atmospheric methane have been obtained from ice cores of
both hemispheres, covering time periods from the preindustrial
era to the penultimate climatic cycle (back to 250,000 yrs
BP). Apart from the recent anthropogenic increase, the most
stricking feature observed in the methane profiles is the
general coherency between CH4 and climate changes. In
particular, the new Greenland CH4 results from the GRIP and
GISP2 drillings reveal that abrupt Greenland climate changes
during the last glaciation and deglaciation are paralleled by
similar methane variations. Methane is in phase (F1 200 years)
with Greenland temperature changes during the deglaciation.
However, some differences appear between the two signals over
the Holocene and in the middle of the last glaciation. Changes
of up to 15% characterize the Holocene methane profile, with a
clear minimum of concentration around 6 Kyr BP, whereas the
temperature signal remains stable. Also, between 40 and 8 Kyr
BP, slow temperature changes have no analogy in the methane
profiles.

The large CH4 changes observed over these various time scales
are thought to result from variations in the hydrological
budget over the continents, affecting the extent of wetlands,
the main natural source of methane. The comparison of CH4
changes, during the last deglaciation and during the Holocene,
with paleoclimatic data on the continents suggests that
low-latitude wetlands were mainly responsible for these
changes and that the role of high-latitude wetlands became
important after about 3 Kyr BP.

As methane has a long enough residence time in the atmosphere,
it can be used as a stratigraphic marker to correlate
Greenland and Antarctic ice-core signals. The use of the GRIP,
GISP2 and Vostok profiles allows us to depict the chronology
of Greenland and Antarctic climatic events during the last
deglaciation and their phase relationship with CH4, CO2 and
ice
volume changes. In particular, the start of the deglaciation
at Vostok appears to lead Greenland temperature, CH4 and CO2
increases, and ice volume decrease.
The comparison of CH4 signals over the Eemian period show that
the sequence of methane changes in the Vostok and Greenland
cores is different, suggesting that the Greenland core
stratigraphy has been altered. A tentative redating of this
part of the GRIP and GISP2 cores is proposed, based on the
combination of CH4 and EB18O of O2 signals of the Vostok core.

>>>>>>>>>>>>>>>>>>>>

CARBON FLUXES IN THE SUBTROPICAL NORTH PACIFIC OCEAN

J.R. Christian and D.M. Karl

School of Ocean and Earth Science and Technology, University of Hawaii 1000 Pope Road, Honolulu, HI, USA 96822

The subtropical oceanic gyres are the largest of the earth's ecological-biogeochemical provinces. They account for a large fraction of global ocean primary productivity and cross-thermocline carbon flux. The ecosystems of the subtropical gyres are dominated by a picophytoplankton-nanozooplankton food web that is poorly parameterized by existing ecosystem models. The relationship between new and primary production and particulate carbon flux to the deep ocean is similarly poorly understood. Because these vast regions of the world's oceans are generally undersampled, improved models of this ecosystem are of great importance in reducing uncertainties in models of the global carbon cycle.

The Hawaii Ocean Time Series (HOT) program has been sampling a hydrostation in the North Pacific subtropical gyre since 1988 and has generated a new understanding of seasonal and interannual variability of biological production in this ecosystem and its relationship to the global biogeochemical cycles of carbon, nitrogen, phosphorus and oxygen. Emerging models of this system show that many assumptions widely incorporated into models of ocean biogeochemistry are inappropriate in this ecosystem. Models incorporating size-specific rates of production and respiration for several phytoplankton and microzooplankton size classes can predict fluxes of carbon to the metazoa and to the bacteria and provide a framework for assessing confidence regions about estimates of processes that are difficult to measure directly. The six years of time-series data obtained to date will be used to estimate net community production and respiration, and statistical evidence will be presented that this ecosystem is a net exporter of reduced carbon.

>>>>>>>>>>>>>>>>>>>>

MODELLING NET ECOSYSTEM PRODUCTION
AND METHANE EXCHANGE IN NORTHERN WETLANDS

T. R. Christensen, J. Kaplan, A. Haxeltine, S. Sitch and
I. C.
Prentice

Global Systems Group, Department of Ecology, Lund
University,
Ecology Building, S-223 62 Lund, Sweden

Methane is an increasingly important greenhouse gas due to its
rising atmospheric concentration, caused mainly by
anthropogenic emissions. However, there are still significant
uncertainties concerning the magnitude and geographical
distribution of its natural atmospheric sources and sinks.
Relatively high early estimates of the contribution from
northern wetlands have been lowered. It is now generally
believed that about 35 Tg CH4/yr originates from wetlands and
tundra north of 50F8N. This represents about 20-25% of all
natural emissions.
A number of studies have shown a correlation between net
primary production (NPP) and methane emission. It has
similarly been suggested that net ecosystem production (NEP)
of wetland ecosystems across a range of latitudes can be used
as a predictor of methane flux. Although these relationships
may hold approximately for annual fluxes, they are incorrect
for seasonal cycles. Both NPP and NEP tend to be highest early
in summer; methane emissions are generally higher towards the
end of the growing season. Total heterotrophic respiration is
a better indicator of methane exchange. While still strongly
linked to NPP, heterotrophic respiration has a more correct
seasonal signal and is constrained appropriately by below-
ground conditions.

A modified version of the BIOME 2 model was used as basis for
an estimation of the global northern wetland contribution to
the atmospheric methane budget. The methane model builds on an
empirical quantitative relationship between total respiration
and methane emission in wetlands. The model has been validated
against observed NPP, respiration, net CO2 flux (NEP), and
methane emission rates at a number of northern wetland and
tundra sites. In order to compare with other global emission
estimates, the widely used Matthews and Fung digitised global
wetland mask was applied to extrapolate fluxes. We thereby
estimate total non-forested bog emission (> 50F8N) to be 10.4 F1
6.9 Tg CH4/yr. This is lower than most other recent estimates.
This estimate does not include forested bogs and
nonforested/forested swamps. Nevertheless, it clearly
conflicts with the total northern wetland figure of 30 Tg
CH4/yr (excluding 5 Tg from mesic tundra) that has been widely
used in recent attempts to model the global methane budget.
Unaccounted-for winter emission, and high emissions that are
localized both in time and space, may partly make up for the
"missing" methane source. However, there still seems to be a
significant lack in our understanding of natural atmospheric
methane sources and sinks, in particular at high northern
latitudes.

>>>>>>>>>>>>>>>>>>>>

TESTING THE ASSUMPTION OF WATER BALANCE LIMITS
CONTROLLING GLOBAL NPP: FROMTHE POTSDAM-95
MODEL INTER-COMPARISONS

G. Churkina and S.W. Running
NTSG, School of Forestry, University of Montana,
Missoula, MT 59812, USA
Phone: (406) 243-6311, Fax: (406) 243-4510,
Email: galina@ntsg.umt.edu

Terrestrial NPP is one of the most-modeled ecological parameters
at theglobal scale. Approaches to its modeling vary and are based
on differentsuites of parameters. Although most of the models
produce similar results atthe global scale, their abilities to predict
NPP at smaller scales differnotably. Inter-comparison of global NPP
models at smaller scale using acommonly-accepted assumption
about their possible behavior is effective inchecking their consistency.
In this study, as a criterion for model inter-comparison, we assume
thatwater is the primary limiting factor of NPP. Current theory and
empiricalanalysis tend to support this assumption for most of the
world92s uplandecosystems (Woodward 1987, Neilson et al. 1989;
Stephenson 1990). Exceptionsare high latitude systems, which are
energy limited. We compared global NPPmodels that were presented
at the 2nd NPP model workshop in Potsdam-95. Inorder to test if
water balance could be considered as the primary driver of NPP for
a model, a water balance coefficient was correlated with mean
annualNPP for each model. The water balance coefficient was
calculated as thedifference of precipitation and potential
evapotranspiration at each gridsell (0.5B0 x 0.5B0 grid) for the
whole globe on an annual basis. Potentialevapotranspiration was
a function of mean annual temperature and radiation.For
consistency with the model92s inputs, global data for precipitation
andtemperature were obtained from climate files by Cramer & Leemans
(1990,updated by Cramer in 1994). Also we gave an overview of the
correlationresults and made some suggestions for future
inter-comparisons of global NPPmodels.

Galina Churkina NTSG Phone: +1 (406) 243-4632
University of Montana Fax: +1 (406) 243-4510
Missoula,MT 59812 Email: galina@ntsg.umt.edu
>>>>>>>>>>>>>>>>>>>>

A THREE DIMENSIONAL MODELING STUDIES
OF O18 IN ATMOSPHERIC CO2

P. Ciais1 , P.P. Tans2, S. Denning3, J.W.C. White4,5,
M. Trolier2,4, J.A. Berry6, and P. Monfray7

1LMCE, CEA, L'Orme les Merisiers, Gif sur Yvette, France

2National Oceanic and Atmospheric Administration, CMDL,
Boulder, Colorado, USA

3Colorado State University, Department of Atmospheric
Sciences,
Fort-Collins, Colorado, USA

4University of Colorado, Institute of Arctic and Alpine
Research, Boulder, Colorado, USA

5University of Colorado, Department of Geological Sciences,
Boulder, Colorado, USA

6Carnegie Institution of Washington, Department of Plant
Biology,
Stanford, California, USA

7CFR, CNRS-CEA, Av. de la Terasse, Gif sur Yvette Cdex,
France

The recent development of complex models of terrestrial
ecosystems requires a validation of the CO2 fluxes exchanged
between plants, soils and the atmosphere. Direct flux measure-

ments can be made at a few location but they may prove
difficult to "scale up" to global scale. Conversely, tracers
in the atmosphere make it possible to derive useful
information on surface fluxes by modeling atmospheric
concentrations.

We present a new 3-D modeling study of the O18 isotope
composition in CO2 and discuss the implications regarding the
gross CO2 fluxes between land biosphere and atmosphere (GPP
and
total ecosystem respiration). We simulate the O18 composition
of atmospheric CO2 (expressed in d18O units) using the 3-D
transport model TM2 [Heimann, 1989], treating separately the
isotopic exchange of CO2 with leaves, soils, ocean and fossil
fuels. The isotopic fluxes on land are derived from the
interactive vegetation model SiB-2. Our simulations are
compared with new d18O flask measurements made at 50 sites of
the NOAA-CMDL global air sampling network. Constraints on the
latitudinal and seasonal distribution of GPP and total
ecosystem respiration are brought by the analysis of the
north-south gradients of d18O in CO2 as well as of the
seasonal
cycle at specific locations.
Denning, S., 1994, Investigations of the transport, sources
and sinks of atmospheric CO2 using a general circulation
model.

Heimann, M., and C.D. Keeling, A three dimensional model of
atmospheric CO2 transport based on observed winds: 2. Model
description and simulated tracer experiments, In Aspects of
Climate Variability in the Pacific and Western Americas,
edited by D.H. Peterson, American Geophysical Union,
Washington DC, 1989.


>>>>>>>>>>>>>>>>>>>>

COUPLING VEGETATION INTO GLOBAL CHANGE MODELS

C. Ciret and A. Henderson-Sellers

Climatic Impacts Centre, Macquarie University
North Ryde, 2109, NSW, Australia

Human activities are producing measurable changes in many
major earth systems, including natural vegetation and the
atmosphere. Modelling the global earth system can help under-

standing the processes and their interactions involved in the
different subcomponents (e.g. ocean, cryosphere, atmosphere,
vegetation and soils), as well as the effects of human activi-

ties on the global system. This modelling task demands that
different types of models have to be linked together. In this
paper, global climate models (GCMs) and vegetation models are
linked in a "one way" mode (i.e. no feedback from the
vegetation model to the GCM is allowed) and the results are
compared with those obtained when the observed climate is
used. The aim of this study is to investigate the sensitivity
of the global vegetation models to the climates simulated by
the GCMs. This includes the analysis of the sensitivity of the
vegetation models to changes in the spatial resolution of a
GCM (i.e. CCM2 that has been run with different spectral
resolutions). In addition, the comparison of the vegetation
distributions obtained with simulated current climates and
with observed climate enables the evaluation of the ability of
the GCMs to simulate the bioclimatic variables required for
the prediction of natural vegetation. The two vegetation
models used are BIOME1 and a version of the Holdridge scheme
tuned to produce vegetation distributions that resemble those
from BIOME1. They are both global static models. The atmo-

spheric general circulation models (AGCMs) employed are the
National Center for Atmospheric Research's Community Climate
Models (CCM): CCM0, CCM1, CCM1-Oz, CCM2 and the Australian
Bureau of Meteorology Research Centre (BMRC) model. Some of
these AGCMs are coupled to ocean models and some are coupled
with a land-surface scheme (e.g. CCM1-Oz with the land-surface
scheme BATS). The horizontal resolutions vary, from coarse
(CCM0, CCM1) through medium (BMRC) to high (CCM2). The
agreement between the vegetation distributions obtained with
observed and simulated climate is poor: for more than 50 % of
the total land area, the vegetation is "incorrectlyr"
predicted when simulated climates are used. The results depend
on the GCM and on the vegetation model used, nevertheless the
range of results vary from about 55 % to 73%. The increase in
the resolution of CCM2 does reduce the discrepancies between
the vegetation distributions obtained with observed and
simulated climate. However, even when a relatively high
resolution version of CCM2 (i.e. T63) is used, the differences
between the vegetation distributions it "predicts" and that
produced using observed climate is still greater than 50 % of
the total land area. It appears also that the vegetation
models react differently to changes in horizontal resolution,
BIOME being more sensitive than Holdridge.

>>>>>>>>>>>>>>>>>>>>

THE GREEN SAHARA AT 6 KA B.P.:
RESULTS FROM AN INTERACTIVE ATMOSPHERE-BIOME MODEL

M. Claussen and V. Gayler

Max-Planck-Institut fuer Meteorologie
Bundesstr. 55, D-20146 Hamburg

Analysis of the climate simulation for 6 ky B.P. with the
Hamburg climate model ECHAM (carried by Stefan Lorenz, Univ.
Bremen, within the framework of the PMIP) reveals that 6 ky
B.P. global vegetation patterns closely resemble present-day
vegetation distributions. This is at variance with
reconstructions (e.g. Frenzel et al., Atlas of Paleoclimates
...) which suggest much more rain in the Sahara than today
with the potential of at least sparse vegetation. Here it is
demonstrated that the obviously unrealistic results from ECHAM
are due to the specification of present-day land-surface
patterns as surface boundary conditions (as was prescribed for
all PMIP runs).

The paleoclimate simulation has been repeated by coupling the
BIOME model of Prentice et al. (J. Biogeography, 1992) with
ECHAM (level 3). Earlier studies by Claussen (Clim. Res.,
1994) indicate that the combinded ECHAM-BIOME model is
sensitive to the initial distribution of land surface
conditions. It was found that under present orbital conditions
and SST distribution, (at least) two stable equilibria of
vegetation patterns are possible: one corresponding to
present-day sparse vegetation in the Sahel, the second with
savanna extending far into the southwestern part of the
Sahara. The former equilibrium is achieved by initializing the
climate-biome model with a vegetation distribution close to
the present-day one, the latter by initially prescribing a
green Sahara.

Similar is valid when simulating the climate with orbital
conditions of 6 ky B.P. During the Holocene optimum, almost
the entire Sahara becomes vegetated except for the Lybian
desert. Both experiments, present-day and 6 ky B.P. climate
simulations, corrobrate Charney's (Quart. J. R. Met. Soc.,
1975) hypothesis of a positive bio-geophysical feedback in the
Sahel. Moreover, they suggest that for paleoclimate
simulations, vegetation has to be integrated into the climate
model as a dynamic component.

>>>>>>>>>>>>>>>>>>>>

TOMS Results in Brazil
Maria Albertina Costa
Abstract

A scientific video were produced using monthly mean data from TOMS (Total Ozone Mapping Spectrometer) inside the nimbus 7 satellite, from 1989 to 1991 over Brazil. Spatial models were designed through the Geographyc Information System and Computer Graphyc. As a result it was observed higher ozone concentrations over the Southern and Western region and lower ozone concentrations over the Northern and Eastern region.

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TOP PREDATORS AS A GLOBAL BIOTIC MEASUREMENT

Authors are Steve Cousins, Pablo Ferreras, Noemi de la Ville
Ecosystems Group, IERC, Cranfield University, Cranfield,
Bedfordshire, MK43 0AL, England.

Abstract

There are theoretical and practical reasons for believing that a global count of remaining top predators is a direct summary measure of human impact on earth. The quantity of energy available to flow through the food web to 'primative' top predators has almost always been reduced by humans (hunting, agriculture, pollution). Estimates are made of the global abundance of major top predators in the assumed absence of humans, i.e. based on climatically derived vegetations, 2000 bp. These predator abundances are a baseline to compare to existing predator abundances. Global top predator count is a QUANTITATIVE measure of biota which complements the QUALITATIVE measure, global biodiversity, where the latter represents the number of types rather than the quantity of life on earth. Quantitative biotic measures may influence the conceptual framework of global modelling and biological conservation. >>>>>>>>>>>>>>>>>>>>

A GLOBAL VEGETATION MODEL USING PLANT FUNCTIONAL TYPES

W. Cramer, H. Bugmann and M. Plchl

Potsdam Institute for Climate Impact Research
P.O.Box 60 12 03, Telegrafenberg, D-144 12 Potsdam, Germany


The comparison of a range of global terrestrial ecosystem
models has shown that fundamental differences exist concerning
the models' capabilities to predict the dynamic response of
the biosphere to changes in climate and ambient CO2
concentration. We present a new, coupled model of global
vegetation structure and trace gas fluxes (the Potsdam Land
Atmosphere Interaction model, PLAI) that differs from previous
ones in considering plant functional types (PFTs) rather than
ecosystems. For the hypothetical case of climate-vegetation
equilibrium, PLAI predicts the composition of potential
natural vegetation (PNV) in terms of fundamental PFTs (e.g.,
trees with different leaf turnover times, or shrubs vs.
grasses), as well as the major biogeochemical processes
concerning the interaction of these plants with the atmosphere
(e.g., net primary productivity, NPP, or actual
evapotranspiration, AET). For the case of human-driven land
cover dynamics, PLAI also simulates the biogeochemical fluxes
for a prescribed mixture of PFTs.
The development of this model towards a dynamic global
vegetation model (DGVM) consists of a gradual inclusion of
processes on several levels of temporal resolution. Presently,
PLAI simulates diurnal and seasonal flux variations for the
case of long-term average climatic conditions. Realistic
weather fluctuations within the long-term means (dry/wet or
cold/warm periods within a year) and interannual variability
(dry/wet or cold/warm years) in the absence of a long-term
trend are features that are currently implemented and under
ongoing validation, using local time series of weather data,
as well as a globally applied stochastic weather generator.
Plausible performance for both cases will be required before
transient simulations are possible.
To progress towards realistic transient behaviour of the model
on the time-scale of decades to centuries, we present a
framework for application of patch-model derived rules for
establishment, competition and mortality of PFTs, and
ecophysiologically derived functions for their growth. The
first simulations will be initialized by conditions of the
equilibrium model, connected to a global land use data base.
At a later stage, the behaviour of the model under different
initial conditions will be tested as well as its response to
an interactive coupling with a general circulation model.


>>>>>>>>>>>>>>>>>>>>

AN ASSESSMENT OF DIFFERENT CLIMATE CHANGE SCENARIOS
FOR THE GLOBAL REDISTRIBUTION OF AGRICULTURAL LAND

W. Cramer1, M. Claussen2 & A. M. Solomon3

1Potsdam Institute for Climate Impact Research
P.O.Box 60 12 03, Telegrafenberg, D-144 12 Potsdam, Germany

2Max-Planck-Institute for Meteorology, Bundesstr. 55, D-20146
Hamburg, Germany

3USEPA Environmental Research Laboratory,
200 SW 35th Street, Corvallis, OR 97333, USA


The central purpose of this paper is to address the issue of
spatial scale in climate change impact scenarios. A problem
arises due to the gap between the coarse, often continent-wide
scales that general circulation models provide information for
and the much finer regional scales required for the simulation
of ecosystem processes. From the point of view of the
atmosphere, only land surface processes at the same resolution
as the climate model can be considered for feedback
simulations. From the point of view of the biosphere, however,
the atmospheric signal must be converted into scenarios at
finer scales if the sensitivity of ecosystems is to be
assessed in a realistic way. The assessment of the statistical
sensitivity of ecosystem change to a climate change signal
requires multiple numerical realisations of different climate
states. This paper uses a series of such realisations. One set
was derived from several general circulation models, and
another one from several time slices of one general
circulation model.
Cramer and Solomon (1993) estimated future redistributions of
potential agricultural land using scenarios derived from four
different general circulation models. Here, we reassess their
study using various realisations of present-day and future
climate simulated by the T42 general circulation model of the
Max-Planck-Institute for Meteorology (Hamburg, Germany). We
show that only the gain in potential arable land on Northern
latitudes constitutes a spatially coherent and statistically
significant signal driven by climate change. The variability
between different climate realisations, along with the lower
amplitude, in tropical and Southern hemisphere regions,
conceals any systematic trend in changing availability of
potential arable land.
A further limitation to the possibility of deriving scenarios
of ecosystem redistribution from general circulation models is
the inappropriate spatial resolution of the climate models.
Here, we demonstrate a procedure of combining a detailed
present-day surface climatology with the climate change signal
from the circulation model. We demonstrate that the method is
capable of producing detailed maps for present-day equilibrium
ecosystem distributions at resolutions between global
circulation models and detailed local weather generators.
Although based on present-day local weather features, we
conclude that the method is suitable for ecosystem
redistribution scenarios.

>>>>>>>>>>>>>>>>>>>>

The Importance of Tropical Ozone for the Chemistry of the Atmosphere: The Need for the Measurement Initiative ITOY, an IGAC Initiative

P.J. Crutzen
(Max Planck Institute for Chemistry, PF 3060, D55020
Mainz, Germany;
+49 6131 305458;email air@mpch-mainz.mpg.d400.de)

As one of the precursor gases of the OH radical, tropospheric ozone plays a key
role in the oxidation efficiency of the atmosphere. Despite its great importance
there still exist major gaps
in knowledge about the distribution of ozone especially in the tropics and subtropics.
To remedy this problem a proposal has been launched within the International
Global Atmospheric Chemistry (IGAC) Core Project of the IGBP to conduct
an intensive measurement campaign of ozone soundings over a period of +2 years
emphasizing the tropics and subtropics (ITOY International Tropospheric Ozone
Years).In this lecture the great importance of such an effort will be outlined.
Measurements have shown that
the tropics and subtropics contain both regions with very low (Pacific Ocean)
and very high (biomass burning influenced) ozone concentrations

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HALOCARBON AND ALKYL NITRATE DISTRIBUTION ALONG THE SOUTH-EAST COAST OF SOUTHERN AFRICA

A. C de Kock1, C. R Anderson2, and C Labuschagne1

1Department of Chemistry, Port Elizabeth Technikon, Private Bag X6011, Port Elizabeth, 6000

2Department of Geology, University of Port Elizabeth, PO Box 1600, Port Elizabeth, 6000

Photochemical processes in the troposphere are known to be influenced by a large variety of trace gases, such as halocarbons, hydrocarbons, ozone, and nitrogen oxides (NOx). Selected halocarbon and alkyl nitrate (RONO2) measurements were performed on ambient air samples taken on the south-east coast of southern Africa. The prevailing meteorological conditions determined whether the air mass sampled was of oceanic, rural continental or urban origin.

The alkyl nitrates quantified in this study were; 2-propyl, 1-propyl, 2-butyl, 1-butyl, 3-pentyl, 2-pentyl, 2-methyl-1-butyl, and 1-pentyl nitrate. Variability in absolute and relative RONO2 mixing ratios were observed on a synoptic time scale. These changes were directly related to the prevailing meteorological conditions. Air masses of an urban origin had significantly higher RONO2 mixing ratios and lower 2-propyl/2pentyl ratios as compared to those of rural continental or oceanic origin. In addition some seasonality was observed in mixing ratios, with higher RONO2 levels evident during winter and early spring and lower levels during summer.

The following halocarbons were identified and quantified in the ambient air samples; dibromomethane, bromodichloromethane, dibromochloromethane, chloroiodomethane, bromoform, 1,2-dibromoethane and hexachloroethane. Biogenic halocarbons observed in seawater samples were; bromodichloromethane, dibromomethane, chloroiodomethane, dibromochloromethane, and bromoform. Using known Henry's law constants, it was found that the seawater was super saturated with these compounds, with respect to their atmospheric concentrations. The biogenic halomethanes, such as bromoform and dibromomethane, exhibited far more variability in their atmospheric mixing ratios as compared to the relatively long lived anthropogenic species such as hexachloroethane. The mixing ratios of the petrol additive, 1,2-dibromoethane, were found to be directly related to local traffic. Under certain meteorological conditions, a correlation between the 1,2-dibromoethane and RONO2 levels was observed.

The results of this study show that the ocean is a major source of biogenic halocarbon species found in the marine troposphere. The alkyl nitrate levels measured for air masses of a marine origin was significantly higher than those predicted by model studies. This, together with the observed changes in relative and absolute concentrations of the alkyl nitrates, supports the hypothesis that long range transport plays a significant role in the distribution of alkyl nitrates in the remote troposphere. It would thus appear that trace gas variability in the coastal troposphere is strongly influenced by biogenic emissions and long range transport.

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#303

THE EVALUATION OF DYNAMICS OF SOIL CARBONATE BUFFER RESERVOIR DURING LAST 4ka

Vitaliy A. Demkin and Yaroslav G. Ryskov

Institute of Soil SCience and Photosynthesis RAS, 142292 Pushkino Moscow Region, Russia

Soil carbonates, being a buffer reservoir, are able either to accumulate or evolve CO2 into the atmosphere according to equation: CO2 + H2O + Ca2+ 3D CaCO3 thus controlling the content of CO2 in the atmosphere. We try to evaluate the dynamics of soil carbonate buffer reservoir using the carbonate supplies in a 2 m layers of paleosoils having the different ages. More than 200 paleosoils in archaeological monuments of the Bronze Age (III-II millennia B.C.) and the Middle Ages (XIII-XIV centuries A.D.) have been studied. The studies were carried out in steppe of Eurasia containing chernozems, chestnut and brown desert-steppe soils.

It has been established that in the Bronze Age paleosoils of all soil-geographic areas were characterized by surface occurrence of carbonates (5-7% CaCO3). For the last 30-40 centuries the carbonates migrated from the upper part of soil profile into the middle one (15-20% CaCO3). The average rate if carbonate leaching was 1 cm/100 years in chernozems and 0.4- 0.8 cm/100 years in chestnut and brown soils. CaCO3 migrated from 0-50 cm layer with the rate of 15-20 and 5-10 g/m annually. The carbonate accumulations in two meter thickness were very labile and depend on soil type, particle size of parent material, geomorphology and of carbonate supplies in soils. Thus, during recent 30-40 centuries, steppe soils did not were the sink of atmospheric CO2, but were the additional source of it.

This work was fulfilled under support of Russian Foundation for Fundamental Investigations, International Science Foundation "Cultural Initiative" and National Program "Global Change of Environment and Climate".

>>>>>>>>>>>>>>>>>>>>

PROGNOSTIC SIMULATION OF ATMOSPHERIC CO2 IN A
GENERAL CIRCULATION MODEL -
EFFECTS OF CORRELATIONS BETWEEN SURFACE FLUXES
AND TRANSPORT

A. S. Denning and D. A. Randall
Department of Atmospheric Sciences, Colorado State
University
Fort Collins, CO 80523 USA

The exchange of carbon dioxide (CO2) between the terrestrial
biosphere and the atmosphere has long been recognized as the
primary driver of the seasonal cycle of atmospheric CO2
concentration at large spatial scales. The physiological
processes responsible for this seasonal cycle are driven by
seasonal changes in solar radiation, temperature, and
available moisture at the land surface. Terrestrial CO2 flux
is
also coupled to physical forcing on the diurnal time scale.
These cycles in the physical forcing drive seasonal and
diurnal cycles in atmospheric circulations as well, which are
strongly correlated to the CO2 flux. Such correlations lead to
a nonuniform distribution of atmo spheric CO2 in the annual
mean even if there is no net annual storage or release of
carbon by terrestrial ecosystems.
We investigated the effects of these diurnal and seasonal
correlations by performing several multiyear prognostic
simulations of atmospheric CO2 concentration using the
Colorado
State University General Circulation Model (GCM) coupled to a
new version of the Simple Biosphere Model (SiB2). Our model
differs from most ecosystem models in that we calculate the
exchange of CO2 between the atmosphere and the land surface at
the atmospheric time step of six minutes, and thereby resolve
the diurnal cycle of the carbon flux. In addition, the model
simulates the diurnal evolution of low-level atmospheric
turbulence, which is a key determinant of vertical transport
of CO2. As a result, the simulated diurnal and seasonal
evolution of CO2 reproduced the limited observational data
much
better than any previous global simulation.
The coupled diurnal cycles of photosynthesis, respiration, and
boundary layer turbulence produced very strong spatial
gradients of annual mean CO2 over biologically productive
continental regions which are not detectable given the present
observational network. Expanding the network to include such
areas could significantly reduce the current uncertainty in
the global carbon budget. Correlations between vertical
transport and CO2 flux on the seasonal time scale produced a
meridional gradient in annual mean CO2 at the current
observational sites that was four times as strong as
previously simulated, implying a stronger net terrestrial
carbon sink than found in previous studies.

>>>>>>>>>>>>>>>>>>>>

INTERACTIONS BETWEEN GLOBAL HYDROLOGICAL AND CARBON CYCLES

R. Dickinson 1, L. Graumlich 2, and R. Bryant 2

Department of Atmospheric Sciences University of Arizona, Tucson, AZ 85721, USA

Tree Ring Laboratory University of Arizona, Tucson, AZ 85721, USA

The BATS land surface package is used for climate simulation with the NCAR CCM2 atmospheric GCM. We have extended BATS to include carbon fluxes by using empirical relationships relating carbon assimilation to stomatal functioning. Our approach differs from what has been done in SIB2 and other land models including carbon in that, rather than deriving stomatal functioning from modeled carbon dynamics, we generalize the existing stomatal parameterization for water so that it includes the assimilation of carbon. Our carbon model attempts to treat in detail various respiratory processes and the partitioning of photosynthate. We assume that as LAI increases, a smaller fraction of photosynthate is given to leaves; although plausible, there is a dearth of observations to quantify this assumption. However, we find that the results are sensitive to the detailed functionality of this dependence of partitioning on LAI. Our carbon model has long suffered from too slow spring growth of leaves at small LAI and a tendency to develop excessively large LAIs. These errors were corrected by changing the function we used for LAI dependence of partitioning to leaf.

With the current version of this model, we have carried out global simulations with the CCM2, which give apparently reasonable fields of NPP and other vegetation related parameters. Our apparently most-significant, novel findings are independent of the details of how leaf photosynthesis was parameterized. In particular, we have found a substantial dependence of global carbon assimilation on the treatment of leaf wetting from dew and precipitation interception. With the model's standard leaf-wetting parameterization, calculated global NPP appears too low; with total neglect of leaf wetting, NPP appears too high. An analysis by Chen et al. (1995) has shown that CCM2 has much too high a frequency of precipitation and too low intensities, which could be a major contributor to excessive leaf wetting. Furthermore, asymmetries between leaf wetting and carbon assimilation may be important; that is, for many plants, stomates are concentrated on the bottom of leaves where wetting would be expected to be less pronounced than on the top.

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SEPAN - SEDIMENT AND PALEOCLIMATE DATA NETWORK

Michael Diepenbroek, Hannes Grobe, Manfred Reinke, Uwe Siems
Alfred Wegener Institute for Polar and Marine Research
Am Handelshafen, 27570 Bremerhaven, Germany


Large scale reconstructions and modelling of paleo
environments and processes require information systems, which
guarantee a consistent storage of data sets of great variety
collected over long time ranges. The information system SEPAN,
initiated by the marine part of the German IGBP-PAGES, was
designed for this purpose. The crucial aspects that had to be
recognized during the conceptional phase of the system were
the data quality and availability in the data domain, and the
usability and adaptability of the system in the structural
domain. Also legal aspects had to be considered.
Data quality can be estimated through full documentation of
data sets and quantification of errors where possible. Data
sets are owned by the producers. They can decide themselves on
the copyrights. If data sets are used in another context, then
they have to be cited thus giving a benefit to data producers.
In this respect the system works like a publication medium.
This not only has a positive impact on the quality and but
also on the availability of data sets.

The varying and changing requirements for the data structure
are compensated by a highly flexible data model, which allows
the storage of all types of samples and parameters. The
adaptability of the system is further guaranteed through
implementation of a client/server environment with simple and
universal components. Servers are accessed via local networks
or internet. The functionality of the system comprises im- and
export of data in common exchange formats, a complex and
flexible retrieval and tabular, graphical as well as geo-

graphical representation of all data with high level front
ends.

The system is fully implemented and was first handed out to
users in 1994. At present, the majority of German marine
samples plus selected international samples, essentially
sediment cores, are stored in the system, and approximately
35,000 data sets of various parameters can be accessed.

>>>>>>>>>>>>>>>>>>>>

TIME-DEPENDENT GLOBAL LAND USE CHANGE

J. Dignon

Global Climate Research Division, Lawrence Livermore National
Laboratory
P.O. Box 808, L-256 Livermore, CA 94550, USA
Human activities have become recognized as a major force in
shaping the biosphere and the Earth's climatic system.
Changing of the land surface through clearing of natural
vegetation for agriculture, pastures, or logging is one
example of human activities that may be of concern. Land-use
and land-cover are important to the biosphere, the Earth's
radiation budget, and the climatic system, through their
effects on albedo, transfer of momentum, and cycles of water
and nutrients. The land surface establishes the boundary
conditions and can change the fundamental behavior of the
global models used to study the Earth's climatic system and
the terrestrial biosphere. Modelers in the past have studied
the effects of land-use/cover change by doing sensitivity
studies and altering the land surface boundary conditions.
Until now, scientists have lacked a vehicle for generating
comprehensive self consistent land-use projections that are
compatible to the structure of global models of biogeochemical
cycles and climate.
We present a temporally and spatially consistent,
research-quality, gridded data set of land cover change
suitable for global change research. We provide an historic
time series (pre-industrial to present) land-use data set
which will contribute previously unavailable information for
global change related use. The data set will be gridded at a
1x1 degree resolution for the period from 1960 to the present.
Earlier historic time periods will be presented at a roughly
5x5 degree resolution. We include approximately twenty
vegetation types and account for sub-grid differentiation. Our
aim in this project is to provide a comprehensive data set
that will lead to a systematic scheme of regionalization of
land-use/land-cover change. By making these global land cover
change data sets easily available, we are providing global
change data that are of broad interest to GAIM and USGCRP
goals.

This work was supported by LLNL's Laboratory Directed Research
and Development Program under the auspices of the U.S. DOE,
Enivronmental Sciences Division, under contract No.
W-7405-Eng-48.


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CHANGES IN THE ECOSYSTEMS OF OASES UNDER THE IMPACT OF
IRRIGATION ACTIVITIES (CENTRAL ASIA)

T. V.Dikariova

Water Problems Institute, Russian Academy of Sciences,
10, Novaya Basmannaya, 107078, Moscow, Russia.

Tedgen and Murgab oases in Central Asia are the hotbeds of
ancient agricultural civilisation that have preserved their
importance as agricultural centers till our days. Studying the
history of man and nature interrelations in these oases we can
point out several crises one of which is the modern period.
Agriculture with irrigation began from the 2nd millenium B.C.
in the Murgab delta and from the 4th millenium B.C. in the
Tedgen delta. At those times the anthropogenic impact on the
ecosystems was minor and it permitted the continuation of the
ecologic balance between nature and society. But changes in
the ecosystems were accumulating, anthropogenic influence
added to the regional and global changes of climate. The end
of Neolitic Age was the period of climate aridisation that
caused the irrigational agriculture in Central Asia. The
pluvial period of the Iron Age at the beginning of the VIIth
century B.C. together with the minor ecological crisis in the
Murgab delta because of removing of the ancient Marg to the
Zotal, caused the improvement of hydraulic engineering and the
prosperity of the Merv oasis. The abatement of pluvial, the
reduction of the flow and the water level lowering in the
Tedgen and Murgab at the beginning of the IVth century B.C. as
well as migration of the delta's branches gave impulse to the
development of irrigation. In the VIII-XIth centuries A.D. the
agriculture and irrigation in the river deltas reached its
peak. But the prosperity of irrigation caused the changes in
the soil-salt balance, the increase of the areas of waste
lands and disturbance of the hydrological regime. So the more
effective system of irrigation caused the more serious
disturbance of the ecological balance and accelerated the
failure of the civilization. At the beginning of the XIIIth
century the civilization of the Tedgen and Murgab oases fell
under the onslaught of the Tatar invasion. In the XXth century
the ramified irrigational systems, cascades of reservoirs and
collector-drainage network were constructed in the deltas of
the Tedgen and Murgab rivers. The valleys of the rivers were
intersected by Kara-Kum channel. The processes are developing
now in this region that can be considered as signes of
ecological crisis. But we can evaluate the state of ecosystems
as threshold state which procede the active desertification.

>>>>>>>>>>>>>>>>>>>>

MODELING CHANGES IN OCEAN NEW PRODUCTION

R. Dugdale and F. Wilkerson,
Dept. Biological Sciences, University of Southern
California,
Los Angeles, CA 90089, USA

The coastal oceans account for about 50% of the world fish
catch and by analogy perhaps 50% of the global marine
biological activity. The response of these coastal ecosystems
to climate perturbations can be approached by modeling new
production, i.e. that production which is available for export
to fisheries, to higher food chain components and downward
flux of particles to the deep ocean. New production models are
based upon the input of external "new sources" of nutrient
which places the upper limit on export production. In most
upwelling systems, nutrient input is strongly correlated with
temperature of the deep source water. Increases in source
water temperature will be associated in decreased nutrient
concentrations. The effect is strong, e.g. in coastal
upwelling off the coast of California, minimum surface
temperatures during strong upwelling are about 9F8C where
nitrate (NO3) concentrations are about 25 E6M, sufficient to
drive very high new production rates and result in surface
pCO2
values well below atmospheric levels. At 13.5F8C, NO3 concen-

trations fall to zero. The entire range of high to zero new
production rates is encompassed by a temperature range of only
4.5F8C. We have used these observations to model NO3 input
(i.e.
new production) from remotely sensed sea-surface temperatures
for both coastal and equatorial upwelling areas.
The recent consensus that diatoms are the major phytoplankton
involved in high rates of new production and the export of
carbon to the deep-sea has re-focused the attention of
biological oceanographers on the role of silicate (Si(OH)4)
required by these (but not by most other) primary producers in
the sea. The Si(OH)4 cycle differs qualitatively from that of
phosphorus and nitrogen in that silicate regeneration is
primarily a chemical process while phosphorus and nitrogen
remineralization occur through various biological agents. The
result is that high Si(OH)4 concentrations are observed at
deeper depths than are NO3 and PO4, strongly suggesting
Si(OH)4
as a primary limiting nutrient for marine biogeochemical
cycles. Changes in deep-water circulation or in dissolution
rates of silicon from diatom shells with changes in
temperature would be reflected in changes in productivity and
in the relation of phytoplankton to the net flux of CO2.
We will present a model showing that ocean systems tend
strongly to Si(OH)4 limitation and that areas considered to be
high in nutrient and anomolously low in new production are in
fact depleted in silicon compared to nitrogen and phosphorus.
Some of these areas are very large and have the potential for
global level effects, e.g. We have proposed that the low new
production rates of the equatorial Pacific upwelling zone and
its consequent role as a net source of CO2 to the atmosphere
is
the result of low Si(OH)4 concentration. Modeling changes in
global new production may be possible using remotely sensed
sea-surface temperature but must involve evaluation of both
NO3
and Si(OH)4 as "new" sources of nutrients to the euphotic
zone.
In addition, predictions made from paleotemperature records
applied to such models may prove useful in understanding past
changes in ocean productivity, especially during glacial
events.

>>>>>>>>>>>>>>>>>>>>

UNDERSTANDING GLACIAL-INTERGLACIAL VARIABILITY
OF THE CLIMATE SYSTEM : A CHALLENGE FOR GAIM

Jean Claude Duplessy

Centre des Faibles Radioactivits, Laboratoire mixte,
CNRS-CEA, 91198 Gif sur Yvette cedex, France

Over the last ten years, paleoclimatic reconstructions derived
from ice marine and lake sediments cores have demonstrated
that the climatic system experienced a natural variability
much larger than that observed during the instrumental and
historical periods. Whereas one single external forcing has
been recognized at the time-scale of glacial-interglacial
changes (insolation variations), the time-dependent behaviour
of the climate system and its steady state under conditions
significantly different from those of today are still poorly
understood, noticeably:

- changes of the biogeochemical cycles, which resulted in
variations of the atmospheric grenhouse gas content (CO2,
CH4);

- changes of the continental vegetation, especially during
climatic events of short duration (Allerod, ...), when the
vegetation had no modern analog;
- instabilities of the polar ice sheets which covered northern
Canada and Europe; they resulted in massive iceberg
discharges, of which the climatic impact is still poorly know
at the global scale;

- changes in the global ocean circulation which were
associated with changes in the location of deep water
convection areas in both the North Atlantic and the Southern
Ocean;

- changes in El-NiA4o frequency;

- changes in the mean rate of oceanic circulation and
ventilation, with rapid turnover during the deglaciation
despite the injection of freshwater at the sea surface;

- abrupt changes in the global climate system, leading to
massive reorganisations of the atmosphere and the ocean; these
changes involved both the hydrological cycle and freshwater
input in the high latitudes and the behaviour of sea ice; they
occur during both glacial and interglacial conditions.

Close cooperation between paleoclimatologists and modellers
should allow to study these changes and better understand the
feedbacks internal to the climate system which act as
non-linear amplifiers of the insolation forcing or after a
perturbation, such as massive iceberg discharges.


>>>>>>>>>>>>>>>>>>>>

TERRESTRIAL PRIMARY PRODUCTIVITY RESPONSES TO
ATMOSPHERIC CARBON DIOXIDE INCREASE

William R. Emanuel1, Thomas M. Smith1, F. Ian Woodward2,and
Herman H. Shugart, Jr.1

1Department of Environmental Sciences, University of Virginia
Charlottesville, Virginia 22903, USA

2University of Sheffield, Sheffield, UK

Increasing atmospheric CO2 may stimulate primary productivity,
causing more carbon storage in land pools. This CO2
fertilization may explain the discrepancy between the observed
CO2 increase and estimates of atmospheric sources and sinks
and
may slow future CO2 increases as fossil fuel use continues. In
addition to increased photosynthetic rate, numerous other
mechanisms including increased water and nutrient-use
efficiencies can be involved in the CO2 responses of ecosystem
biogeochemistry. Global patterns simulated by a primary
productivity model at 28, 31.5, 36, 52, and 72 Pa atmospheric
CO2 indicate CO2 sensitivity. The model simulates primary
productivity by evaluating representations of basic processes
including the biochemical reactions within leaf cells, the
control of CO2 supply and moisture loss by stomatal responses
to assimilation rate and water availability, and nitrogen
uptake and allocation within the leaf canopy. The model
adjusts leaf area to satisfy constraints on carbon and
moisture balance. The analysis shows significant response over
substantial areas; however, different mechanisms can be
responsible for similar responses in different biomes or
regions. An important GAIM activity is to coordinate com-

parison of these CO2 responses as indicated by different
global
models.

>>>>>>>>>>>>>>>>>>>>


Ian Enting


CSIRO Division of Atmospheric Research
and Co-operative Research Centre for
Southern Hemisphere Meteorology
PMB 1, Mordialloc, Vic 3195 Australia
Fax 61-3-586 7600 (DAR) 61-3 -550 9181 (Monash)

THE ROLE OF INVERSIONS IN GREENHOUSE GAS STUDIES
I.G. Enting
CRC-SHM, CSIRO, Private Bag 1, Mordialloc,
Vic 3193, Australia


A major cause of uncertainty
in projections of relations between future emissions
and concentrations of COO has been uncertainty in the
current atmospheric COO budget (Schimel et al., 1995; Enting
et al., 1994). (There are similar problems with methane, Fung
et al., 1991). The IPCC calculations worked with the
atmospheric COO increase expressed as:

IT Increase 3D Anthropogenic forcing Natural dissipation hfill (1) However, to discuss the uncertainties, it is essential to
expand (1) as: IT Increase 3D Forcing Dissipation + Natural variability hfill (2) To refine the analysis it is necessary to subdivide the
components of (2) further as:
IT Dissipation 3D Ocean + COO-fertilisation hfill (3) IT Forcing 3D Fossil + Land-use + Other forcing hfill (4) IT Variability 3D Oceanic + Terrestrial hfill (5) To resolve these components, secondary characteristics
of the fluxes are investigated, particularly:
isotopic composition, associated O$_2$ fluxes,
temporal variability,
and spatial distributions.

The deduction of source/sink strengths from spatial
distributions is known as inversion and requires the use of a
model of atmospheric transport.
This paper examines ways of integrating tracer inversions into more general
studies of the carbon cycle.


The main difficulty is the ill-conditioning of the inversion
problem. This means that, in the absence of additional
constraints, the estimates of fluxes are arbitrarily
sensitive to errors in the observations or in the transport
model.

Since tracer inversions are not generally able to produce
sufficiently accurate global budgets on their own, it isimportant to
integrate inversions with other carbon cycle studies.
One integrative approach is the Bayesian synthesis inversion(Enting et al., 1993, 1995).
Other carbon cycle
studies provided prior estimates of the sources for use in
the estimation.This was an important advance, both in the systematic
estimation of uncertainties and in the use of multiple types
of information. The disadvantage was that all other
calculations were subordinated to the atmospheric modelling
and forced into the same
statistical framework (least-squares
fitting) as is used for the atmospheric inversion.
It is primarily a one-way inference
process. There is little scope for feeding the output of the
inversion back into analyses of the individual components.

It seems worthwhile investigating ways in
which the chain of inference could be turned around.
In order to do this, it would seem to be neccessary of have
some form of `objective' output from atmospheric inversions.
This seems particularly difficult in view of the inability of
inversions to resolve averages over regions with sharp
boundaries (Enting, 1993).

Since the objective is to reduce the uncertainties in current
greenhouse gas studies, a pre-requisite of judging the success
is a statistical analysis to actually quantify these
uncertainties.
There is a need for more sophisticated statistical models
going beyond the least squares fitting used by Enting et al.
(1993, 1995). Enting (1993) gives some preliminary
investigations.

begin list setlength leftmargin 1.5em
setlength itemindent -1.5em
setlength itemsep - parsep

I Enting, I.G. 1993 IT Inverse Problems 9, 649-665.
I Enting, I.G. et al. 1993.
CSIRO, DAR, Tech. Paper No. 29
I Enting I.G., Wigley, T.M.L. and Heimann, M. 1994 CSIRO, DAR, Tech. Paper No. 31
I Enting, I.G., Trudinger, C.M. and Francey, R.J. 1995
IT Tellus , 47B, 35-52.
I Fung, I.Y. et al. 1991 IT J. Geophys. Res. , 96D,
13033-13065. I Schimel, D. et al.
1995 In: IT Radiative Forcing of
Climate. Ed. J Houghton et al. (CUP)
% I Tans, P.P. Fung, I.Y. and Takahashi, T. 1990. IT
Science , 247, 1431-1438. % I Tans, P.P. Berry, J.A. and
Keeling, R.F. 1993 IT Global % Biogeochemical Cycles ,
7, 353-368.
>>>>>>>>>>>>>>>>>>>>

GLOBAL SYSTEMS INTEGRATION:
ATMOSPHERIC CHEMISTRY AND THE CLIMATE RESPONSE
OF EARTH SYSTEM MODELS

D. J. Erickson III and G. P. Brasseur

Theoretical Studies and Modelling Project,
Atmospheric Chemistry Division,
National Center for Atmospheric Research,
Boulder, CO 80307-3000

We describe global, 3-D general circulation model (GCM)
simulations of the distributions, fluxes and climate impact of
various atmospheric trace species including 13CO2, 12CO2, N2O,
F-11, CH4, SO2, DMS and SO43D. The spatial resolution of the
model is 2.8o x 2.8o latitude-longitude in the horizontal with
18 vertical levels. The time step used varies from 20 minutes
to 12 hours depending on what scientific problem is being
addressed. Feedbacks between the physical climate system and
the chemistry of the atmosphere are introduced sequentially
and include the model dynamical response due to the radiative
impact of greenhouse gases and anthropogenic sulfur. We
outline a series of numerical experiments whereby the
biogeochemical cycles alter the atmospheric GCM radiative
balance and subsequently the hemispheric circulation.

The atmospheric GCM is run using a variety of surface forcing
treatments. Ocean general circulation models, terrestrial
biosphere models and satellite CZCS (ocean color) data merged
with atmospheric GCMs are examples of the many approaches to
constrain the surface forcing. We emphasize the coupling of
observational data and detailed models of surface chemical
exchange. We describe model experiments where chemistry runs
are merged with atmospheric dynamical model runs. This effort
is part of the Climate System Modelling (CSM) activity at
NCAR.


>>>>>>>>>>>>>>>>>>>>

THE ATMOSPHERIC SULFUR CYCLE AND ITS IMPACT ON THE
SHORT-WAVE RADIATION BUDGET: A MODEL STUDY

J. Feichter

Max Planck Institute for Meteorology,
Bundesstr. 55, D-20146 Hamburg, Germany.

Aerosols influence the shortwave radiation balance directly by
scattering and absorbing solar radiation. Indirectly they act
as cloud condensation nuclei (CCN) affecting the cloud micro-

structure and hence, the optical properties. Anthropogenic
aerosol sources have increased significantly over the past
century mainly due to fossil fuel use and biomass burning. The
major contribution to aerosol radiative forcing produced from
these anthropogenic sources appears to be sulfate particles.
Emissions, transport, chemistry and rainout of sulfur species
are calculated on-line with the meteorology in a global
atmospheric circulation model (ECHAM). The resulting sulfate
aerosol concentrations are used to compute their influence on
clear-sky and cloud albedo. As a first estimate the radiative
perturbations through sulfate aerosols are not allowed to
interact with the model climate to be able to separate the
forcing from climate feedbacks.
The importance of different oxidation pathways for sulfate
formation will be discussed and calculated surface
concentrations of DMS, SO2 and sulfate will be compared to
observations. The radiative forcing at the top of the
atmosphere associated with the predicted sulfate
concentrations will be presented.

>>>>>>>>>>>>>>>>>>>>

A HIGH RESOLUTION HOLOCENE AND LATE GLACIAL
ATMOSPHERIC CO2 RECORD: VARIABILITY TIED TO CHANGES INOCEAN THERMOHALINE CIRCULATION

R.A. Figge1, J.W.C. White1, P. Ciais2, and V. Markgraf1

1Institute of Arctic and Alpine Research and Department of
Geological Sciences
Campus Box 450, University of Colorado, Boulder, CO 80309-0450
USA

2LMCE, CEA Saclay, 91191 Gif-sur-Yvette, France

Here we present a new method for reconstructing atmospheric
CO2
based on stable carbon isotopes in peat. The CO2 record from
the Harberton peat core in Patagonia (55F8S 72F8W) has decadal
resolution and spans 14,000 radiocarbon years. The late
glacial (10-14 ka) is characterized by three large and rapid
CO2 pulses at 10.2, 11.6, and 12.9 ka. When compared to two
high resolution marine core records, Troll 3.1 and RC11-83,
and to records of atmospheric D14C, these CO2 pulses appear to
be controlled by changes in the ocean's thermohaline
circulation. Two broad Holocene excursions are identified at
4.2 and 7.7 ka. The driving mechanism behind these excursions
appear to be different than those in the late glacial.

Three tests of the accuracy of the peat CO2 method are
presented. These tests rely on the rapid (~1 year)
interhemispheric mixing time of CO2. Because of the global
signature of CO2, records of CO2 from different climatic
settings should be identical. In the first test, the Harberton
CO2 record is compared to two Antarctic ice core CO2 records.
In the second test, the Harberton late glacial CO2 record is
duplicated in another peat core from Patagonia. Finally, the
anthropogenic CO2 increase due to fossil fuel burning and
deforestation over the last century is captured in a third
peat core. All tests are positive.

The Harberton CO2 record indicates that throughout the late
glacial as well as the Holocene, the natural carbon cycle has
been characterized by instability rather than one or two
stable modes. How this instability in CO2 is amplified or
modified by anthropogenic influences remains an open question.


>>>>>>>>>>>>>>>>>>>>

PROCESSES OF TRANSPORTATION AND SEDIMENTATION
OF DUST AEROSOL

A. Finaev

Department of Geography and Ecology
Acadamy of Sciences
33 Rudaky Ave., 734025 Dushanbe, Tajikistan

Physico-geographical and climate conditions of the deserts of
Middle Asia and of the mountain ranges of Tyang-Syang and
Pamiro-Alai have tied together the system of deflation
processes in the desert landscapes and of deposition of dust
matter at mountain foothills. During the dust storm in a
Middle Asian desert the dust aerosol is distributed throughout
the troposphere almost uniformly up to the top of convective
layer (velocities of both the horizontal and vertical eddy
fluxes reach tens of meters per second then). The air mass
loaded with aerosol enters the Tajikistan area and fills the
closed valleys lying below that convective layer. Meeting the
hardly penetrable barriers of mountain ranges the air
stagnates, its eddy mixing weakens, and the aerosol starts to
precipitate to ground. Part of these air masses overflows the
ridges. To substitute it new portions dusty air arrive. A
continuous feeding of the area by dusty air masses takes place
during such dust episodes. That explains the overall duration
of haze.
Starting from such a picture of the processes of aerosol
transport and introducing the initial data available we may
calculate the amount of precipitated aerosol as described
below. The actual data on periodicity and duration of dust
haze, combined with the data on actual site height above the
sea level were used as the basis for calculations of the rate
of aerosol precipitation in Tajikistan. Variability of the
depth of convective layer during the year was also accounted
for, calculated, as it were, following the technique developed
elsewhere (Finaev, 1987, 1988, 1994). It varied from 950 m
above sea level in January to 4850 m in June. Calculations of
precipitated depths were conducted for each month separately
at every station recording haze episodes. The analysis of data
in conjunction with physico-geographical situation at station
testifies to a dependence of deposit depth on the absolute
height of station above the sea level, on the local climatic
features at station, and on the distance from dust storm
origin centers. Depth of the layer precipitated during the
year varies from 0.04 mm/yr to 0.683 mm/yr. The averaged rate
of accumulation of sediments over the Republic is 0.2 mm/yr.
Approximately the same data were obtained for the early
Holocene when calculating the depth of soil horizons,
corresponding to that temporal cross-section (0.17 to 0.26
mm/yr) (Lomov, 1991). A layer less than 0.1 mm thick is most
probably completely eroded and does not take part in
accumulating sediments. The annual trend of material
accumulation is not homogeneous and depends on climate
variability.

>>>>>>>>>>>>>>>>>>>>

The Integrated Biosphere Simulator (IBIS) Project
byJonathan A. Foley
Climate, People and Environment Program (CPEP)
Institute
for Environmental Studies
1225 West Dayton StreetUniversity
of Wisconsin
Madison, WI 53706+01 (608) 265-5144 (phone)
+01 (608) 262-5964(fax
jfoley@facstaff.wisc.edu (email)Abstract: To improve the understanding of global ecological processes, and toevaluate their potential response to natural and anthropogenicperturbations, a variety of numerical models have been developed. For themost part, these models have evolved to consider the structure (e.g.,vegetation cover, species composition) and function (e.g.,evapotranspiration, photosynthesis) of terrestrial ecosystemsindependently. In fact, three different classes of terrestrial biospheremodels have emerged:(1). Atmospheric General Circulation Models (AGCMs) used to simulateclimate often simulate the biophysical interactions between land surfacesand the atmosphere using _land surface models_, which describe the energyand water balance of the soil-vegetation-atmosphere system and operate withprescribed distributions of vegetation and soil characteristics. However,changes in vegetation cover that may result from climate change willsubstantially alter land surface characteristics (e.g., albedo, rootingdepth) and thus could produce important feedbacks on the climate system.(2). The spatial distribution of vegetation types and their relationshipto climatic parameters have been examined using _equilibrium vegetationmodels_, which simulate: (a) the selection of possible plant functionaltypes (i.e., which plants can grow and reproduce), (b) the competitionbetween plant functional types for resources (e.g., water, light), and (c)the resulting equilibrium vegetation cover.(3). _Terrestrial biogeochemistry models_ have been used to examine theflow of carbon and mineral nutrients within terretrial ecosystems. Thesemodels have been used to examine the global patterns of net primaryproduction and carbon storage, and their sensitivity to climate change.The emergence of these separate model classes has made it somewhatdifficult to address the complex issues associated with global change andterrestrial ecosystems. In particular, examining the response ofecosystems to multiple, and potentially interacting, factors and how theresulting changes in the terrestrial biosphere may influence theatmosphere, requires a more integrated perspective. Also, nearly allexisting biosphere models focus on the equilibrium structure and functionof ecosystems; however, to better understand the effects of human activityon the biosphere, the time dependent behavior must be examined as well.Models should be designed to simulate the full range of dynamic behavior ofterrestrial ecosystems, including vegetation dynamics, and its consequenceson to biogeochemical and hydrological cycles.The next step in model development should be the creation of an integratedbiosphere model. To tackle this challenge, we are building a new model --IBIS (the Integrated Biosphere Simulator) -- at the University ofWisconsin. We will present: (1) the current state of development andvalidation of the integrated biosphere model, and (2) how we plan to usethe model to improve our understanding of the terrestrial biosphere and itsresponse to anthropogenic and natural perturbations.Currently, IBIS (version 1) operates on a 2 degree by 2 degree global gridwith a 30 minute timestep. The physical parameterizations of the surfaceenergy and water balance have been adapted from an AGCM land surface model(LSX v.2) to better facilitate direct coupling with AGCMs. To simulatecarbon fluxes, the model uses physiological parameterizations ofphotosynthesis, respiration and canopy conductance. On an annual timestep,the carbon balance of plant functional types is updated, allowing fortransient changes in the vegetation cover. The global simulations ofvegetation cover, primary productivity, and surface water balance for themodern climate will be presented. In particular, the time-dependentchanges in vegetation cover from a variety of intial conditions to theresulting equilibrium states will be examined >>>>>>>>>>>>>>>>>>>>

CONTRIBUTIONS OF ATMOSPHERIC CO2 FERTILIZATION,
NITROGEN DEPOSITION AND CLIMATIC VARIABILITYON THE
BIOSPHERE-ATMOSPHERE CO2 EXCHANGE

P. Friedlingstein1, I. Fung2 and A. Dai1
1NASA/GISS, 2880 Broadway, New York, NY 10025, USA

2SEOS, Univ. of Victoria, Victoria, BC V8W 2Y2, Canada


Several mechanisms are known to lead to an imbalance between
the CO2 fluxes going in and out of the biosphere. In this
study, we investigate the potential impact of increasing
concentration of carbon dioxide in the atmosphere, growing
level of atmospheric nitrogen deposition on land, and climatic
variability (temperature and precipitation) on the biosphere-
atmosphere CO2 net flux.

The global gridded model we use, SLAVE, accounts for 10
vegetation types. 6 carbon pools are considered (herbaceous
and woody compartments in phytomass, litter and soil). The
driving variables for the estimation of carbon pools and
fluxes, i.e. temperature, precipitation, atmospheric CO2, and
nitrogen deposition are time varying. In order to estimate the
year by by year evolution of the biosphere, we use the
temperature and precipitation annual variabilities over the
20th century interpolated on the SLAVE 5 X 5 degree grid,
historical time serie of atmospheric CO2, and distribution of
anthropogenic nitrogen deposition on land obtained with the
GISS atmospheric transport model.

Integration from 1850 up to 1990 gives informations on the
temporal as well as spatial distributions of the biospheric
carbon uptake.


>>>>>>>>>>>>>>>>>>>>

A PROGNOSTIC MODEL OF GLOBAL TERRESTRIAL ECOSYSTEM DYNAMICS

A. D. Friend and A. K. Stevens

Institute of Terrestrial Ecology, Edinburgh Research
Station
Bush Estate, Penicuik, Midlothian EH26 0QB,
Scotland, UK

A global model (Hybrid v3.0) of terrestrial ecosystem dynamics
is presented. The model treats soil and vegetation dynamics,
and their interaction. It predicts the short-term fluxes of
carbon, water, and nitrogen, as well as the longer-term
processes of vegetation succession and soil organic matter
dynamics. Fluxes are calculated on a daily timestep; the allo-

cation of carbon and nitrogen within trees occurs annually.

Hybrid v3.0 has been written with three major requirements in
mind: (i) the carbon, water, and nutrient cycles must be fully
coupled in the soil-plant-atmosphere system; (ii) the internal
constraints on the model's behaviour, and the driving forces
for the model, must be the same as those which operate in
nature (e.g. climate, nitrogen deposition, and the atmospheric
concentrations of CO2 and O2); and (iii) the model must be
constructed so that it is capable of predicting transient as
well as equilibrium responses to climate change. These
conditions have largely been met by constructing the model
around a set of fundamental hypotheses regarding the general
constraints under which plants and soils behave, independently
of any particular location or time. The model is thus
potentially capable of making reliable predictions of
ecosystem behaviour and structure under future, new,
atmospheric conditions.
The model is run globally at the half-degree scale using a
daily weather generator. The distributions of needleleaved and
broadleaved evergreen tree, broadleaved cold and dry deciduous
tree, and C3 grass generalised plant types (GPTs) are
predicted for current and future climates. The total amount of
carbon stored in the vegetation and soils is also predicted,
both at equilibrium and during transient simulations. In
addition to the effects of climate change, the model is also
perturbed by changes in the atmospheric concentration of CO2
and the rate of nitrogen deposition, with significant impacts.

A sensitivity and uncertainty analysis is described; attention
is drawn to the areas of the model that need further analysis,
both from modelling and experimental perspectives.

>>>>>>>>>>>>>>>>>>>>

Atmosphere-Biosphere CO2 Exchanges for the past
200 years: Implications for
a Detection Strategy

Inez Fung (NASA GISS and University of Victoria)
Pierre Friedlingstein and Aigou Dai (Columbia University)

A terrestrial sink for anthropogenic CO2 has been
inferred from
variations of CO2 and C13 in the atmosphere, but is yet
not supported by
large-scale field evidence. We use a simplistic biospheric
carbon model to
propose a strategy for field measurements. The model
incorporates
carbon-nitrogen-water interactions and simulates
pool sizes and inter-pool
fluxes of 5 above-ground and below-ground
compartments. Data for temperature,
precipitation, atmospheric CO2 levels and nitrogen
deposition for the past 100
years are used as forcing to the biospheric model.
We hypothesize that the
anthropogenic CO2 signal may be found in the
ecosystem(s) and ecosystem
pool(s) with the maximum signal (CO2 and
nitrogen fertilization) and minimal
noise (climate-induced fluctuations).
------------------------------------


>>>>>>>>>>>>>>>>>>>>

A MODELLING STUDY ON RESPONSES OF ALKALINE
GRASSLAND ECOSYSTEMS IN NORTHEAST CHINA TO CLIMATE CHANGE
IN RELATION TO DIVERSITY AND SPATIAL PATTERNS

Qiong Gao

Institute of Botany, The Chinese Academy of
Sciences
Beijing 100044, China

Temporal variations of spatial coverage patterns of major
plant species in the alkaline grasslands in northeast China
subject to climate change were studied using a spatial simu
lation model. The model stressed the coupling between soil
alkali and vegetation coverage. Succession and spatial
migration of plant species were modelled in light of soil
alkaline conditions as well as climate variables. The
variation of soil alkali was in turn considered to be
dependent on the amount of surface vegetation. Precipitation
and evapotranspiration were treated as external driving
variables. The modelled species coverage patterns were shown
in close agreement with observations on a fenced one-hectare
alkaline grassland from 1989 to 1993.
The effects of climate change on the species coverage were
studied by subtracting the output patterns of the model under
present climate conditions from those under changed climate
conditions. To relate the difference patterns to various
landscape indices such as patchiness, contagion, fractal
dimension and diversity indices, the one-hectare region was
divided into 25 subregions with each subregion containing 100
grid cells. The difference in species coverage between the
present and changed climate conditions and spatial pattern and
diversity indices were computed for each subregion. A
statistical analysis showed that for plants with wide ranges
of tolerance to soil alkali and strong spatial migration
capability, the impact of climate change was significantly
related to spatial pattern, but not to diversity. However, for
plants with narrow ranges of tolerance to soil alkali and less
capability to migrate spatially, the impact of climate change
was related to both diversity and spatial pattern.
Two different treatments were applied to the computation of
the spatial pattern and diversity indices. Conventional
indices were calculated so that all patch types in a subregion
were distinct patch types. Since the dynamic behavior of a
system is usually characterized by a few important indicator
patch types, the conventional indices may not be good
descriptors of system behavior. To avoid the problem, partial
indices were defined to depend on specific patch types. A
partial index of a specific patch type, or a group of patch
types, was computed by treating the patch type(s) under
consideration as distinct patch type(s), but all other patch
types as one lumped patch type. The result of statistical
analysis showed that the partial indices described much better
the species coverage increments than conventional indices.


>>>>>>>>>>>>>>>>>>>>

A SPATIAL SIMULATION OF RESPONSES OF NORTHEAST
CHINA TRANSECT TO ELEVATED CO2 AND CLIMATE CHANGE
USING VEGETATION INDEX

Qiong Gao and Xinshi Zhang

Institute of Botany, The Chinese Academy of
Sciences
Beijing 100044, China

Green biomass dynamics of the ecological transect in northeast
China, ranging from 42F8 to 46F8 of north latitude and from 108F8
to 132F8 of east longitude, was modelled using spatial
simulation with a process-based model, NECT. State variables
of the model included green biomass of 12 vegetation
categories (Larix conifer forest, Pinus koraiensis and
deciduous broadleaf mixed forest, deciduous broadleaf forest,
woodland and shrub, Stipa baicalensis grassland,
Aneurolepidium chinense grassland, Stipa grandis grassland,
desert grassland, wetland and salty meadow, Caragana sandy
shrub, one-crop agricultural field and two-crop agricultural
field), and soil water contents of 2 soil layers. The modelled
monthly green biomass of all the vegetation categories was
converted into NDVI, or Normalized Difference Vegetation Index
of AVHRR. A comparison between the modelled and the observed
NDVI from 1986 to 1990 was made at a 10-minute spatial
resolution.
Simulations for global change used 3 input variables: ambient
CO2 concentration, temperature and precipitation. An average
10% increase in relative plant growth rate was assumed for
doubled CO2 concentration. Effects of precipitation and
temperature increase on sunshine percentage, relative
humidity, radiation, evapotranspiration and eventually plant
growth and soil water, were considered. Two levels of CO2
concentration (present, doubled), temperature increment (0,2F8
C) and precipitation increment (0,10%) were combined to give 8
simulation runs for 30 years with an integration time step of
one month. Instead of assuming step changes in the
environmental variables, linearly continuous variations of the
three input variables were used.
The result of simulation showed that in general the negative
effect of temperature increase on biomass production is much
stronger than the positive effect of precipitation increase in
the prescribed ranges. An increase of 2F8C in temperature alone
gave a 25% decrease in the average green biomass in 30 years.
With the present climate conditions, doubled CO2 concentration
led to a 30% increase in the average green biomass in 30
years. In contrast, an 10% increase in precipitation alone
gave only a 3% increase in the average green biomass in the
same time period. The simulation on a combination of doubled
CO2 concentration, a 10% increase in precipitation and a 2F8C
increase in temperature predicted that the overall green
biomass increase in 30 years will be approximately 8%.

>>>>>>>>>>>>>>>>>>>>

GLOBAL IMPACT OF AFRICAN AEROSOLS, PART II:
SEASONAL DISTRIBUTIONS AND RADIATIVE BALANCES


M. Garstang1, R. Swap1, S. Ulanski2 and P.D. Tyson3


1Department of Environmental Sciences, University of Virginia,
Charlottesville, VA 22903
2Department of Geology and Geography, James Madison
University,
Harrisonburg, VA 22807
3Climatology Research Group, University of the Witwatersrand,
P O Wits, 2050, South Africa

Regional distributions of aerosols over southern Africa are
shown by Tyson et al. (Part I) to be contained in preferred
pathways which extend over the adjacent oceans as well as
being concentrated over the subcontinent. The vertical
distribution of aerosols in the atmospheric column shows
preferential distributions at low and high altitudes
constrained by persistent and widespread stable layers. Two
major regions are identified over southern Africa and the
adjacent oceans together with three subregions which show
pronounced differences in the height and concentrations at
which the aerosols occur. In Region I, the Intertropical
Convergence Zone, aerosols occur in the upper troposphere
below the tropopause. In Region II(a), the Continental
Subtropical Anticyclone (STAC), aerosols are trapped below 4
km and are frequently highly concentrated. In Region II(b),
STAC Ocean West, the aerosols are trapped below 4km, but decay
by deposition rapidly westwards. In Region II(c), STAC Ocean
East, the aerosols are elevated and extend over large
longitudinal distances.

Aerosol Optical Thickness (AOT) observations from the AVHRR
satellite are used to display the annual, seasonal and monthly
distributions of aerosols off NW, SW and SE Africa. The
regional characteristics determined for the Southern
Hemisphere are applied to the AOT distributions in the
Northern Hemisphere. The column profile of aerosols are
determined for each region and used as a basis to calculate
heating and cooling rates in the column due to the presence of
aerosols. Heating rates reverse sign from low to high
altitude locations implying differences in heating and cooling
in each region identified. The regional differences in
heating/cooling rates depart from estimates of aerosol heating
rates based upon uniform distributions of aerosol global
circulation models suggesting that regional differences in
aerosol distributions cannot be ignored when estimating the
global impact of these aerosols.

>>>>>>>>>>>>>>>>>>>>

A FOUR BIOME MODEL FOR CARBON EMISSIONS FROM WETLANDSAND ASSOCIATED BIOMES
C.P.Geevan

Ecosystem Modelling & Simulation Division, Salim Ali Centrefor Ornithology & Natural History, Kalampalayam, Coimbatore
641 010, INDIA

Wetland biomes are major sources of carbon and accounts for an
estimated 12 to 20% of the total contribution to green house
gases. The wide variability in the estimates of net carbon
emission from wetlands point to knowledge gaps in our
understanding of the biogeochemical cycles.

Recent studies indicate strong correlations of the carbon
mobilization, particularly methane fluxes with net ecosystem
production, water table and temperature. Changes in total
wetland area could initiate ecological changes resulting in an
overall reduction in the sequestration rates.

Conceptual framework and a mathematical model are developed
for simulating the carbon exchange processes in wetlands,
addressing the inter-dependence of wetland and the associated
ecosystems. The generalised four biome model comprise of
wetland (A), associated areas of high biomass productivity
(B), areas of medium productivity (C) and human impacted areas
of very low productivity (D).

Each of these biomes consist of two carbon compartments:
living phytomass and dead organic matter or humus in soil. The
carbon pathway in biome A has an additional compartment to
account for anaerobic processes and methanogenesis. The CO2
uptake by living phytomass from atmosphere is modelled as a
non-linear (Bertalanffy) kinetic. Increase in soil organic
content is assumed to promote carbon uptake as result of
enhanced vegetative growth, subject to a saturation point.

A non-linear dependance is assumed between the extent of area
under biome A, and that of the associated of biomes B and C.
Reductions in biome A will result in the decrease of both B
and C, while the total area under biome D will register a
corresponding rise, since the total area is a constant. The
total carbon storage is modelled as a function of the
productivity and area of each biome.

The generalised four biome model of wetland and associated
biomes also provides a modelling framework for incorporation
of important variables associated with global changes into
biome specific models of global carbon fluxes. The preliminary
results of numerical computation show that continued loss of
wetland biomes will eventually lead to drastic reduction in
total carbon sink strength of all the four biomes.

>>>>>>>>>>>>>>>>>>>>

NEW ESTIMATES OF CARBON STOCK AND EXCHANGE
IN TUNDRA BIOME WORLDWIDE

T.G. Gilmanov1,2

1Center for Ecology and Productivity of Forests, Russian
Academy of Sciences Novocheriomushkinskaya st., 69, Moscow,
117418, RUSSIA

2Global Change Research Group, San Diego State University,
San Diego CA 92182-0057, USA

Fluxes and stocks of carbon in ecosystems of the Tundra biome
are significantly affected by the processes of global change.
Tundra ecosystems, in their turn, also influence the global
carbon cycle through a number of feedback mechanisms. To
accurately assess the significance of Tundra biome to global
carbon exchange and balance, quantitative geographically
referenced estimates of the amounts and fluxes of organic
matter in tundra ecosystems are needed.New empirically based estimates of the reserves and fluxes of
carbon in Tundra biome were obtained using the Global
Arctic/Alpine Climate-Soil-Plant Productivity Database
(Bazilevich (1992; 1994); Gilmanov (1993; 1995, in press);
Karelin, Gilmanov & Zamolodchikov (1994); Gilmanov & Oechel
(1995, in press)). This database contains phytomass, producti-

vity, climatic and soil characteristics for more than 300
individual ecosystems described in the literature during the
last 30 years all worldwide.

Multivariate numerical analysis of the information from the
database resulted in formulation of phenomenological models
relating productivity of different types of tundra ecosystems
to available ecological factors-predictors. For preliminary
estimation of net primary production (NPP, t ha-1yr-1) the
equation using most easily available data on annual
temperature Tyr (F8C) and soil organic matter reserve H (t
ha-1) may be applied (Fig. 1):
NPP 3D 1.33*exp(0.027*Tyr+0.0036*H). (n 3D 66; R2 3D 0.63; s.e.3D
1.6) (1)

<< Figure 1 comes here >>

Fig. 1. Net primary production (NPP, t ha-1 yr-1) of zonal
tundra ecosystems in relation to annual temperature Tyr (F8C)
and soil organic matter H (t ha-1) (n 3D 66, R2 3D 0.63, and
s.e. 3D 1.6 t ha-1 yr-1). a: data subset (points) and the
approximating response surface (equation 1), open and solid
points lie below and above the surface respectively. b:
Scatter diagram of empirical versus calculated NPP (equation
1), the 1:1 line is drawn for comparison.If additional information is available, e.g. data on soil
nitrogen N (t ha-1) and green phyto-mass G (t ha-1) reserves,
a more accurate model (Fig. 2) may be used:

NPP 3D 3.83*exp(0.012*Tyr+0.05*N)/(1.0+2.45/G), (n 3D 39; R2 3D
0.80; s.e. 3D 1.35). (2)

<< Figure 2 comes here >>

Fig. 2. Net primary production (NPP, t ha-1 yr-1) of zonal
tundra ecosystems in relation to total soil nitrogen N (t
ha-1), amount of green phytomass G (t ha-1), and mean annual
tempe-rature Tyr (F8C), n 3D 39; R2 3D 0.80; s.e. 3D 1.35 t ha-1
yr-1. a: Data subset (points) and the approximating response
surface (equation 2, Tyr 3D -9.2F8C), open and solid points lie
below and above the surface respectively. b: Scatter diagram
of empirical versus calculated NPP (equation 2), the 1:1 line
is drawn for comparison.

Information from the database was used to interpolate the
layers of phytomass, net primary productivity, climatic and
soil characteristics for all the Tundra biome areas of the 1x1
degree GIS of the Northern hemisphere above 60F8N latitude.
Phenomenological models were applied as interpolation tools
where empirical productivity data were not available
presently. The quantitative estimates of organic matter stocks
and productivity fluxes for the circumpolar Tundra biome were
obtained by integrating the maps of distribution of phytomass,
soil organic matter reserves, and net primary production.
(Table 1).Table 1. Organic matter reserves (Gt d.w.) in live phytomass
(combined aboveground and belowground), soil organic matter
(Gt d.w.), and net primary production (Gt d.w. yr-1) for
ecosystems of the circumpolar Tundra biome (1 Gt d.w. 3D 109 t
dry organic matter)

Hemisphere ZoneAreaPhytomass Soil organic matter
(0-0.5 m layer) Net primary production
106 km2 Gt Gt Gt yr-1
Eastern (Eurasia) tundra 2.60 3.97 44.91
0.67
forest tundra 0.44 2.24 10.44 0.17
Western (North America tundra 4.12 4.99 91.31
0.98
and Greenland) forest tundra 1.38 4.19 19.20 0.50
Total Tundra biome tundra 6.72 8.96 136.22 1.65
forest tundra 1.82 6.43 29.64 0.67

Based on a wider empirical basis, these estimates compliment
and specify the ranges of phytomass, soil organic matter, and
NPP yr-1) of the Tundra biome available in the literature
(Rodin, Bazilevich & Rozov, 1975; Whittaker & Likens, 1975;
Lieth, 1975; Atjay et al., 1979; Bolin et al., 1979; Post et
al., 1982; Miller et al., 1983; Schlesinger, 1984; Olson et
al., 1985; Lashof, 1988; King et al., 1989; Jenkinson et al.,
1991; Bliss & Matveyeva, 1992).

>>>>>>>>>>>>>>>>>>>>

DEPOSITION RATES OF BIOGENIC IONS FROM BIOMASS BURNING
IN THE BRAZILIAN SAVANNA (CERRADO)

P. Girard1, L. Moreira-Nordemann1 and N. Ri Poppi2

1Instituto Nacional de Pesquisas Espaciais, C.P. 515,
12201-970
Sco Josi dos Campos/SP, Brasil. Fax: (0123) 21.77.43, e-mail:
Pierre@met.inpe.br
2Universidade Federal do Mato Grosso do Sul, Departamento de
Qummica, 79070-900 Campo Grande/MS, Brasil. Fax (067) 787 -
5314.

The atmospheric emission of pollutants from burning of the
cerrado and tropical forest has received increasing attention
since the beginning of the 1990's. However, actual
calculations of the pollutants deposition rates in the tropics
are rather scarce. Deposition rates are indispensable to
evaluate the net flux of pollutants to the atmosphere. In this
work, we present, for the first time, deposition fluxes of
soluble elements in the city of Campo Grande (Mato Grosso do
Sul State), in Brazil's cerrado. The predominant atmospheric
pollution source in Campo Grande is presumably biomass
burning. Wet, dry and total (wet + dry) deposition rates were
calculated from rain and atmospheric particulate matter (PM)
mean chemical compositions obtained from one full year of
continuous rain and air sampling (Moreira-Nordemann et. al., ;
Ri Poppi et. al, pers. comm.). The total deposition fluxes for
the first year of measurements range from 0.16 to 2.66
mg/m2.day (Fig. 1). The dry season deposition rates are
markedly greater than those of the wet season due to an
increase in elemental concentration in the air PM and rain
during this period (Fig. 1). This increase was hypothetically
linked to the large number of fires and reduced rainfall
during the dry season. To test this hypothesis, a multivariate
regression analysis was performed. The weekly element
concentration of each ionic specie, both in air PM and
rainfall, was used as the dependent variable while the weekly
fire number (Setzer, pers. comm.) and inverse of the total
rainfall were used as independent variables. For the air PM,
the biogenic ions, K+, SO4--, NO3- and NH4+, showed a strong
correlation (r > 0.8, Table 1) to the fire number and inverse
rainfall. The weaker correlation of Ca++ and Mg++ to the
independent variables indicates that the soil, which was not
taken in account by the regression analysis, is an important
source of these elements. The low correlation displayed by Cl-
and by Na+ suggest a distant, probably maritime, origin for
these elements (confirmed by a Cl-/Na+ 3D 1.74, sea water 3D
1.78). For the rainfall, the biogenic ions and Ca++ displayed
correlation coefficients greater than 0.8, suggesting that Ca
aerosols produced by fire are more readily dissolved in the
rainwater than soil aerosols. The multivariate regression
analysis also yielded model equations linking each of the
biogenic element concentration, both in the air PM and
rainfall, to the fire number and the inverse total rainfall.
Fromthese equations, mean dry season concentration were
obtained and total deposition rates calculated. These model
fluxes consistently underestimated those obtained from the
data. These equations also allowed the estimation of the
deposition rates (wet + dry) attributed to fire. These low
range estimates, represent from 29 to 56 % of the biogenic
elements total deposition fluxes (Fig. 2). However, they only
account for a fraction of the biomass burning emission
estimates1,2, available in the literature, indicating that
burning of the Brazilian cerrado may add significant quantity
of biogenic ions to the atmosphere (Table 2).
Table 1 : Multivariate regression analysis correlation
coefficients. Ionic specie as the dependent variable while the
fire number abd inverse rainfall are the independent
variables.
__________________________________
Ionic Specie Air PM Rain
__________________________________
Na+ 0.52 n.a.
Ca++ 0.61 0.86
Mg++ 0.65 0.66
K+ 0.86 0.82
Cl- 0.29 0.61
SO4-- 0.81 0.89
NO3- 0.81 0.87
NH4+ 0.86 0.84
__________________________________
PM : particulate matter; n.a. : not available


Table 2: Emission and deposition rates from biomass burning in
the Brazilian cerrado. Rates in mg/m2.day.
_____________________________________________
Emission |Deposition
________________________|____________________
K 3.44 |K+ 0.43
SO2 2.29 |SO4-- 0.83
Total N 6.66 |Total N 1.16
______________________________________________

Emission rates : cerrado burned dry matter from 1, emission
ratios from 2. Emission calculation method from 2. Total N;
emission: N2O, NOx and NH3 converted to equivalent N amounts
and summed; deposition : NO3- and NH4+ were converted to
equivalent N amounts and summed.
_______________________________________________________
Ionic specie Dry season Wet season Annual
Ca++ 0.91 0.54 0.73
Mg++ 0.16 0.14 0.16
K+ 0.91 0.31 0.59
Cl- 1.81 3.04 2.66
SO4-- 2.85 2.20 2.59
NO3- 3.09 2.10 2.64
NH4+ 1.98 1.19 1.61
________________________________________________________
Fig. 1 : Annual and seasonal deposition rates (mg/m2.day).
Note that the dry season deposition rates are markedly higher
for all ionic species except Cl-.


______________________________________________________________
_________
Biogenic ion Burning deposition Natural deposition Total
deposition
K+ 0.43 0.48 0.91
SO4-- 0.83 2.02 2.85
NO3- 1.35 1.74 3.09
NH4+ 1.10 0.88 1.98
______________________________________________________________
__________
Fig. 2 : Deposition rates (mg/m2.day) from biomass burning
during the dry season. Total deposition (burning + natural) is
obtained from the original data set. Burning deposition rates,
calculated from the model equations, account for about 50% of
the K+ and NH4+ total deposition.

1.Setzer, A. & M.C. Pereira. 1991. Ambio, vol. 1, 19-22.
2.Andreae. M. O. 1991. in Global Biomass Burning, Atmospheric,
Climatic and Biospheric Implications., J. S. Levine ed., MIT
Press. 3-21.

>>>>>>>>>>>>>>>>>>>>

Global Carbon Cycle Change and Oceanic Biota

V.G. Gorshkov

Theoretical Department, Petersburg Nuclear Physics Institute,
Russia


see faxed copy

(Abstract # 33)


>>>>>>>>>>>>>>>>>>>>

MODELLING OF OCEAN- ATMOSPHERE COUPLED VARIABILITIES AT DIFFRENT TIME SCALES.

P. GOSWAMI

CENTER FOR MATHEMATICAL MODELLING AND COMPUTER SIMULATION
BANGALORE
INDIA

Abstract
The tropical ocean- atmosphere system is known to exhibit a number of
characteristic variabilities at different time scales, ranging from
interannual to intraseasonal. The biosphere, and in particular the
agroclimate of the monsoon and tropical region is significantly affected
by these variabilities. The devastating effects of El-Nino events on regional
ecology provide a prominent example. Variabilities at intraseasonal timescales
like 30-60 days can significantly affect the spatio- temporal distribution
of rainfall, and thus affect agricultural prospects for large populations.
Many of these variabilities are influenced by ocean- atmosphere coupling.
That El-Nino and Southern Oscillation ( ENSO) is a manifestation of unstable
air- sea interaction in the tropics has been known for a long time. However,
recent observational analysis shows that air- sea interaction plays important
role even at intraseasonal (30-60 days) time scale. Success of ocean -
atmosphere coupled General Circulation Models (CGCM) for operational
forecasting depends critically on their ability to simulate these variabilities.
Thus a thorough understanding of various mechanisms involved in genesis and
dynamics of these variabilities is a primary requisite, so that appropriate
parameterization may be included in the CGCMs. It is wellknown that modelling
of air- sea interaction is crucial to the performance of coupled models. Most
of the conventional parameterization of air- sea interaction in the tropics
have been focussed on the mechanism of coupled variabilities with interannual
timescales, and in particular ENSO. In the present work we propose and show
that modelling of air -sea interaction in the tropics requires a (time) scale
specific approach. While for coupled variabilities at shorter ( intraseasonal)
timescale the coupling is likely to be dominated by convective processes in
the atmosphere, for interannual time scale it is the direct forcing of the
atmospheric boundary layer by sea surface temperature, as envisaged in
conventional parameterization, that governs the coupled variabilities. The
physical and observational basis of scale- specific parameterization of air-
sea interaction are discussed. Finally, implications of the proposed
parameterization for development of coupled models in the tropics are outlined.


>>>>>>>>>>>>>>>>>>>>

"OPTIMISTIC" MODELING - A TECHNIQUE TO GAIN
RELIABLE PREDICTIONS?

C. Greiner1,2,3, F.J. Radermacher1, T.M. Fliedner2

1Research Institute for Applied Knowledge Processing (FAW),
Helmholzstr. 16, 89081 Ulm, Germany

2Institute for Occupational and Social Medicine, University of
Ulm,Albert Einstein Allee 11, 89070 Ulm, Germany

3Central Institute for Biomedical Engineering, University of
Ulm,
Albert Einstein Allee 11, 89070 Ulm, Germany

This presentation concentrates on the importance of making
more reliable information available for the public and for
politics concerning global trends in present economic and
population dynamics and presents a methodology to gain
generally accepted standard reference data. Such data can be
the basis for an appropriate risk analysis and management at a
global level.

The underlying idea is as follows. In order to decisively
support all types of initiatives for sustainable development,
generally accepted standard reference data should be supplied
as a basis for projections and decision making. While it may
be difficult to agree on correctness, reliability, and
adequacy of data, it should be possible to characterize data
as being either optimistic or pessimistic, e.g. bounding the
real data in a reliable way.

As a research paradigm towards the aim of reliable
predictions, a coarse and "optimistic" modeling framework is
proposed. This framework separates scenarios of politically
important future input variables for the model from
corresponding optimistic predictions, using optimistic
modeling techniques based on monotonic structures to derive
standard reference data. This is an appropriate method,
because concentrating on (overly optimistic) bounds is
sufficient rather than forecasting precise data. This means
making the real situation look friendlier - the reality will
be worse. Nevertheless, even these data and projections are
rather alarming for many scenarios and different possible
political actions. Therefore, even such optimistic data is
often a reasonable basis for political decision making.
The investigations of the described concept has shown that a
simplified and possibly unrealistic overoptimistic modeling
technique can be a serious alternative or supplement to more
detailed approaches in a number of situations. The chosen
technique allows production of reliable bounds for data types
which influence the well-being of humans, such as population
growth, environmental development, economic development,
education, and health, on the basis of an over-optimistic
modeling technique. Standard reference data and resulting
predictions based on that data for special interest areas are
a reliable data source, in the sense of correctly bounding
behavior of the future outcome. Such information might lead to
a more defensible basis for public debates concerning risks
and resulting consequences due to certain policies. This might
be a strong aid in reaching a more stable situation for our
environment, an aim which is closely coupled with improving
the quality of life on Earth from a global perspective.


>>>>>>>>>>>>>>>>>>>>

EXAMINATION OF MODEL UNCERTAINTY AND
PARAMETER INTERACTION IN THE GLOBAL CARBON
CYCLING MODEL (GLOCO)

T.M. Grieb1,2, R.J.M. Hudson3, N. Shang1, R.C. Spear1,
S.A. Gherini2, R.A. Goldstein4

1Environmental Engineering and Health Sciences Laboratory
University of California, Berkeley, USA

2Tetra Tech, Inc. Lafayette California, USA

3Institute of Marine Sciences
University of California, Santa Cruz, USA

4Electric Power Research Institute
Palo Alto, California, USA

Complex simulation models are being used to study carbon cycle
dynamics and ecosystem responses to changes in atmospheric
composition and climate. There is a need to establish the
magnitude and sources of uncertainty associated with model
predictions in order to achieve a better understanding of
simulated systems, to increase the reliability of model
predictions, to guide field surveys and laboratory
experiments, and to define realistic values that should be
used in scientific, economic and political discussions of
future conditions.
Monte Carlo simulation is a basic tool that is now used
routinely to quantify uncertainties associated with model
predictions. However, these methods are not directly suitable
for large models with high spatial resolution, and they
provided little information about the interaction between
model parameters. A new tree-structured density estimation
technique has been developed that extends the ability of Monte
Carlo- based analyses to explore parameter uncertainty and
interaction in complex environmental models. The application
of the technique is demonstrated using the global carbon cycle
model GLOCO. The magnitude and sources of uncertainty are
identified in a set of simulations aimed at establishing the
relative importance of the terrestrial biome as a sink for
atmospheric carbon. The combined effects of individual model
parameters and the interactions between model parameters as
well as the interaction between different submodels are
examined. The use of these new uncertainty analysis techniques
in the calibration of complex models with high spatial
resolution is also addressed.

>>>>>>>>>>>>>>>>>>>>

MISSION OF GREENHOUSE GASES BY DECOMPOSITION OF ORGANIC WASTE

A. Gronauer1, G. Depta1, S. Neser1, M. Helm1, S. Schattner-Schmidt1;

B. Hellmann2; K. Schaefer3, R. Haus3

1 Bayerische Landesanstalt fuer Landtechnik, Technische Universitaet Muenchen-Weihenstephan (LTW), Voettinger Str. 36, D-85350 Freising, Germany

2 Institut fuer Bodenoekologie, GSF - Forschungszentrum fuer Umwelt und Gesundheit GmbH, Ingolstaedter Landstrasse 1, D-85758 Oberschleissheim, Germany

3 Fraunhofer-Institut fuer Atmosphaerische Umweltforschung (IFU), Kreuzeckbahnstr. 19, D-82467 Garmisch-Partenkirchen, Germany

More and more organic waste is neither deposited nor burned but composted. Until now only odor was regarded as a problem, especially for composting- yards which have not got enough distance to their neighborhood. Greenhouse gases such as CO2, CH4 and N2O instantaneously do not disturb anybody, but they might have a global importance. In literature, no measurements are known. In order to set up a balance for carbon, nitrogen, methane and other climate-relevant trace gases, an appropriate data basis has to be brought about.

To estimate the emission of greenhouse gases by composting organic wastes, the emission rates from open-air composting clamps (triangular form, 12 x 2,5 x 1,5 m length x width x height) were measured with a closed-chamber method and GC by LTW and GSF. To get the emission during the turning of the clamp, a fan was installed on top of the turning machine. In a tower on the other side of the fan it was possible to measure air-flow and gas concentrations of the exhausted air. Further measurements with high-resolution FTIR, GC and other equipment were made at a housed composting plant equipped with bio-filters. IFU made extractive measurements of greenhouse gases, NH3, and NO inside the composting clamp by a FTIR spectrometer with White cell and emission rate measurements of these gases by open-path FTIR and Gaussian dispersion modelling. In the end of May measurements will be made for a complete open- air composting plant (clamps triangular form, 20 x 2 x 1,2 m) by IFU and LTW. The measurements already show a strong dependence of N2O, CO2 and CH4- emissions from the part of structure material in the clamp. With growing parts of structure material the emission got less. Turning the clamps does not contribute considerable to the total emission. With the data of CH4 emission a first estimation was calculated: If all organic waste in Germany would be treated by composting in open-air composting plants, the emission of CH4 would rise for 0,5 % of the actual emission from agriculture. The effect of bio-filters on climate-relevant trace gases can be described as follows: The bio-filter examined did not change H2O, CO2, CH4-emissions compared to the unfiltered exhausted air, CO was lowered by 50 %, N2O increased by 25%. Ammonia, an important environmental pollutant, was filtered nearly total. Complete date is not analyzed yet but will be represented on the poster.

Further measurements have to be made on this field. Even for the whole agricultural section, only few data is obtainable on climate-relevant gases. LTW, GSF, IFU and other German and European institutions in agricultural science are planning further actions to provide appropriate data for modeling agricultural systems as subsystems in the global cycle of carbon and nitrogen.

>>>>>>>>>>>>>>>>>>>>

A MODELLING ENVIRONMENT FOR ANALYZING
IMPACTS OF CLIMATE CHANGE ON VEGETATION

W. Grossmann1, M. Hitz2, M. Antonovsky1

1Institute for Statistics, Operations Research and Computer
Methods
University Vienna, A 1010 Vienna, Universit4tsstrasse 5,
Austria

2Institute for Applied Computer Science and Information
Systems,
University Vienna, A 1010 Vienna, Universit4tsstrasse 5,
Austria

One class of possible models for investigating the impacts of
climate change on vegetation are process models which try to
mimic the dynamic behavior of landscape. Basically such models
consider the elementary processes of production, regeneration
and mortality in combination with some spatial distributional
models. Although the generic structure of the models is more
or less the same, defined by our understanding of biological
processes, there is a great variety of possible realizations
differing with respect to emphasis on special processes,
functional description (eg., different growth models), granu-

larity and spatial resolution. Also the used input data are of
different nature. As a consequence the comparison of resultsis
rather difficult.

The paper describes a modelling environment which tries to
overcome these problems at some extent using the ideas of
reusable models which are discussed by the simulation
community in recent years. The environment is based on three
basic components:(i) a model base management system providing the necessary
means for model building and long term maintenance of
reusable models and their specifications;
(ii) a data base management system tailored to the specific
needs of spatial time series data;
(iii) a simulation and experimentation environment
supporting post processing facilities for comparison of
results obtained by different simulation runs.

The model base management frees the user from the burden of
defining the model explicit in a programming language but
allows the specification of the model by a Graphical User
Interface (GUI). Models are built stepwise by starting from a
generic model frame which is refined and made more precise by
using submodels and methods stored in a methods library. The
generic frame allows the definition of hybrid models which
combine features of continuous system simulation with aspects
of discrete event simulation. For example a growth model
formulated as a differential equation may be combined with an
event oriented mortality or regeneration model. Furthermore
discrimination (e.g. with respect to spatial structure) can be
made explicit by defining copies of a model which are allowed
to interact with each other, i.e. so called array models.
A simulation experiment is now defined by the chosen
resolution of the generic model frame together with the data
selected from the data base. This tight connection of models
and data allows identification of gaps between desired models
and models, possible with existing data. After simulation the
results are stored in the data base and can be processed
furtheron (e.g., comparison of results from different models
or statistical analysis of results).
The general ideas are examplified by showing how different
types of community models (e.g yield type models or gap
models) can be formulated within this framework and combined
with spatial data.


>>>>>>>>>>>>>>>>>>>>

A CONSERVATIVE TRACER REFLECTING THE STRENGTHS OF THE
OCEAN CARBON PUMPS AND THE UPTAKE OF ANTHROPOGENIC CO2

N. Gruber1 and J.L. Sarmiento2

1Climate and and Environmental Physics, Physics Institute,
University of Bern, SidlerstraE1e 5, CH-3012 Bern, Switzerland

2Program in Atmospheric and Oceanic Sciences, Princeton
University,
Princeton, NJ, USA

see faxed copy


>>>>>>>>>>>>>>>>>>>>


ANALYSIS AND INTERPRETATION OF GLOBAL
MULTIANNUAL SATELLITE DATA OVER LAND

G. Gutman and A. Ignatov
Satellite Research Laboratory,
Office of Research and Applications,
NOAA/NESDIS, Washington, DC 20233, USA

The Advanced Very High Resolution Radiometer (AVHRR) on board
operational NOAA satellites provides daily global measurements
of reflected and emitted radiation from the Earth. These data
contain information on surface characteristics, such as
albedo, temperature and state/amount of vegetation. Global
time series for the period April 1985 - September 1994 from
NOAA-9 and 11 have been mapped into a 0.15 degree grid,
calibrated, cloud screened, averaged on a monthly basis,
spatially interpolated and smoothed.

Preliminary analysis of these data shows spurious
discontinuities/trends resulting from satellite replacement
and orbit drift, large atmospheric perturbations caused by
volcanic eruptions, and possible residual sensor calibration
errors. Replacement of satellites and orbital drift affect the
solar (0.63 and 0.85 micron) and thermal IR (10.8 and 12
micron) channels through variation in illumination geometry
and diurnal heating/cooling of the surface-atmosphere system.
Examples to illustrate the magnitude of these effects will be
given. Before the satellite data can be used for climate
change assessment, data quality and processing procedures have
to be substantially improved.

The presently available data, however, are valuable for
developing a reference state for assessment of climate trends
in a long-term perspective using data from future sensors
compatible with AVHRR. A monthly average climatology has been
constructed based on a 5-year sample of the available time
series that is least subject to the above effects and is
therefore more reliable. Preliminary results with the data of
the past decade show potential for detecting and interpreting
the seasonal cycle and statistically significant interannual
variability, especially in geographic regions with smaller
atmospheric, angular and diurnal variability effects. In
particular, it is useful for monitoring anomalies from
recently launched NOAA-14 and other satellite systems until a
new improved climatology is developed. Global monitoring
potential will be demonstrated.

Spectral reflectances, vegetation index and brightness
temperature can be used to derive variables directly related
to numerical climate model simulations such as surface albedo,
fraction of green vegetation, and clear-sky afternoon surface
temperature. The global data on surface albedo and green
vegetation fraction are useful inputs to the models whereas
the afternoon surface temperature can be used for validating
the model outputs. Examples of global maps of these geo-

physical variables will be presented.

>>>>>>>>>>>>>>>>>>>>>>>


MODELING COUPLED LAND-ATMOSPHERE HYDROLOGIC
PROCESSES

W. Gutowski, Jr.1, C. Vrsmarty2, M. Person3, Z.
99tles1,
B. Fekete2 and J. York3

1Department of Geological and Atmospheric
Sciences,
3021 Agronomy, Iowa State University, Ames, Iowa50011, USA

2University of New Hampshire, Durham, New Hampshire,
USA

3University of Minnesota, Minneapolis, Minnesota,
USA

Understanding land-atmosphere coupling is critical to modeling
regional impacts of climate variability manifested in
hydrologic cycle changes. To approach this problem we have
developed a Coupled Land-Atmosphere Simulation Program
(CLASP), which emulates an atmospheric GCM gridbox with higher
horizontal resolution given to surface processes, including
river transport, groundwater evolution, and
surface-vegetation- atmosphere exchange. The CLASP is
currently applied to two focus areas: a region encompassing
the FIFE field experiment, which provides a host of validation
observations, and a synthetic basin used for sensitivity
studies. External boundary conditions for the model come from
either contemporary climate analyses or from analyses modified
by COHMAP simulations for various episodes in the past 20k
years.
The CLASP is used to address a central question: what is the
influence on quantitative water budgets of surface
heterogeneity that is subgrid in resolution to an atmospheric
GCM's resolution? A primary contributor to the heterogeneity
is the regional variation of vegetation. Initial computations
suggest that resolving surface heterogeneity has only a modest
impact on the exchange of moisture between the surface and the
atmosphere (~ 40 W m-2 out of ~ 250 W m-2 total). More
important
is the effect of resolving the vegetation heterogeneity on
surface processes, especially groundwater recharge and river
flow. The overall behavior suggests that choosing appropriate
surface resolution is highly critical for modeling surface
processes but less so for simulating coupling with the
atmosphere.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

#298
SEALEVEL CHANGE AND ITS IMPACT ON THE PAST AND PRESENT ECOSYSTEMS IN THE MANGROVES OF SOUTH BENGAL, INDIA

Arghya K. Hait1 and Sunirmal Chanda2

1Center for Study of Man & Environment
CK - 11, Sector-II, Salt Lake City
Calcutta-700 091

2Dept. of Botany, Bose Institute, 93/1, A.P.C. Road Calcutta-700 009

Mangrove ecosystem is highly dynamic, being exposed to land- sea-air interactions and their impact on hydrological, geological, meteorological, biochemical and ecological factors, which represents a unique and specialized adaptations. The mangroves are typical inhabitants in the area between mean sea level and mean high water spring tide i.e. they are intertidal. Owing to intertidal nature, their occurrence in sediments provide reliable information in past sea level at the time of deposition.

Analytical results of the samples up to a maximum depth of 50 m have revealed the character of palynomorphs at different stratigraphical horizons supported by carbon-14 dates. The palynomorphs were clearly comparable with the present day Sunderbans mangrove palynomorphs, indicating shifting of the sea level and strand line during the Pleistocene - Holocene times.

The present day sea level in this area shows a rising tendencies possibly due to the accelerated global warming and land subsidence. An integrated analysis of past sea level changes will be utilized to predict the future trend of sea level fluctuations.

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LAKE RECORDS OF REGIONAL CLIMATE CHANGES AT 6000 YR
B.P.:
A GLOBAL ANALYSIS

S.P. Harrison, G. Yu, P.E. Tarasov, B. Damnati, B.
Qin

Dynamic Palaeoclimatology Group, Department of
Physical
Geography, Lund University, Slvegatan 13, S-223 62 Lund, Sweden

Lakes respond to changes in the water balance over the lake
and its catchment by changing in depth and area. Changes in
water depth affect the physical, chemical and biological
characteristics of the lake, and indications of these changes
are preserved in the sedimentary record. Geological and
biostratigraphical investigations of lake sediments can
therefore provide a well-dated qualitative record of the
changes in lake volume. In some regions, especially semi- arid
regions, geomorphological investigations also provide direct
quantitative evidence for former high lake levels. Since 1992,
there has been an international effort to provide a new
documented data base, including both types of lake records,
for the past 30,000 years. This effort has been motivated by
the possibility of using lake data as a record of past
hydrological changes for climate model validation. The new
global lake data set contains records from nearly 700 sites
worldwide and thus is a unique palaeoclimate resource.
Lake records for 6000 yr B.P. show a major expansion of the
Afro-Asian monsoon. In Africa, the lakes indicate the
penetration of monsoonal rainfall as far north as 21F8N, into
what is now the central Sahara. This is accompanied by
somewhat drier conditions in the the equatorial zone,
particularly in eastern Africa, suggesting that monsoon
expansion was accompanied by a northward shift in the ITCZ.
The lakes also indicate wetter conditions associated with
monsoonal-type circulation in the American southwest and in
southern Europe. In the northern mid-latitudes, the lake data
indicate drier conditions in North America and Europe.
However, the lakes provide no evidence of mid-continental
drying in northern Eurasia. The limited evidence from the
northern high-latitudes suggest conditions wetter than today.
Lake data from the southern mid-latitudes are limited, but
suggest conditions wetter than today in the zones now
characterised by Mediterranean-type climates in southern
Africa and Australia.
The lake data thus show that the climate of 6000 yr B.P. was
significantly different from today with respect to the
regional water balance. The broad-scale patterns provide a
benchmark for the validation of climate model simulations of
the climate of 6000 yr B.P. Preliminary comparisons of these
patterns with several climate model simulations conducted
within the framework of the Paleoclimate Modelling
Intercomparison Project (PMIP) show that the simulated
expansion of the Afro-Asian monsoon in response to insolation
changes consequent on changes in the earth12s orbital
parameters is consistent with the observed climate changes;
however, the climate models consistently underestimate the
extent of the monsoon expansion. The simulations show
pronounced aridity in the northern mid-continents, consistent
with the lake data from North America but not with the lake
data from central Eurasia. Isolating the mechanisms underlying
these discrepancies between the simulated and observed climate
at 6000 yr B.P. is a challenge for the future, and should help
to provide a better understanding of the mechanisms of climate
change.
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EFFECTS OF THE HYDROLOGICAL CYCLE ON CARBON FLUXES

P.M. Haugan1, L. Lundberg2 and J.L. Sarmiento3

1Nansen Environmental and Remote Sensing Center
Edv. Griegsvei 3a, N-5037 Solheimsviken, Norway

2Department of Oceanography, University of
Gothenburg
Box 4038, S-400 40 Gothenburg, Sweden

3Atmospheric and Ocean Sciences Program, Dept. of
Geological
and Geophysical
Sciences, Princeton University, Princeton, New Jersey
08544,
USA

Thermal and freshwater forcing of the ocean surface are key
elements of the physical climate system. Surface heat flux is
known to be a controlling factor for the solubility pump of
the ocean carbon cycle and therefore important for the air-sea
CO2 exchange including its geographical distribution. In the
present paper we investigate to what extent surface freshwater
fluxes including run-off exercise control on net ocean carbon
fluxes. Such links between the hydrological cycle and the
carbon cycle could be useful for diagnosing elements of the
carbon cycle during climatic conditions which differ from the
present state. Furthermore, knowledge about the hydrological
cycle may be utilized in estimates of carbon fluxes in the
present climate, and thus indirectly to understand the
geographical distribution of air-sea CO2 fluxes.
The net water flux from the Pacific to the Arctic Ocean
through Bering Strait is estimated to transport carbon at
rates in excess of 0.6 PgCyr-1. The Arctic Ocean serves as a
transit region for this flux towards the Atlantic, adding
approximately 0.1 PgCyr-1 from river run-off. CO2 uptake
mainly
in the Nordic Seas has been estimated to add another 0.1
PgCyr-1, so that there is a net flux of 0.8 PgCyr-1 into the
North Atlantic, most of which is explained by the net water
transport. Starting from these fluxes of freshwater and
carbon, we use available global observations and budgets of
evaporation, precipitation and runoff, and carbon content of
river water, to estimate associated carbon fluxes across
latitudinal sections in the Atlantic. The loop, which may be
viewed as a lateral global carbon conveyor, continues via the
Southern Ocean northward through the Pacific until it is
closed at our starting point in the Bering Strait.
The carbon fluxes associated with the net water flux, are then
combined with measured advective carbon fluxes to estimate
air-sea exchange of CO2 in each latitude band, by subtracting
off the industrial component calculated from model results.
The results indicate that not only the carbon transport from
land to sea associated with run-off, but also the interbasin
net water flow, is a significant determining factor for the
geographical distribution of air-sea exchange of CO2. Thus,
despite the fact that water vapor in the atmosphere carries
very small amounts of carbon, the strength and variability of
the hydrological cycle can determine important aspects of the
global carbon cycle.
>>>>>>>>>>>>>>>>>>>>>>>


BIOME2: A COUPLED CARBON AND WATER FLUX MODEL TO PREDICT
GLOBAL VEGETATION STRUCTURE AND FUNCTION

A. Haxeltine and I. C. Prentice

Global Systems Group, Department of Ecology, Lund University,
Ecology Building S-223 62 Lund, Sweden. E-mail
alex@planteco.lu.se

A coupled carbon and water flux model (BIOME2) has been used
to capture the regional scale environmental controls on the
natural distribution of vegetation structural and phenological
types.
BIOME2 includes a photosynthesis model based on the Farquhar
model, with maximum photosynthetic rates derived using an
optimization theory. Canopy conductance is treated as a
function of the optimal photosynthetic rate and water stress.
A water-balance model incorporating a simple planetary
boundary layer parameterization predicts regional evapo-

transpiration as a function of the canopy conductance,
equilibrium evapotranspiration rate and soil moisture. This
scheme results in a two-way coupling of the carbon and water
fluxes through canopy conductance.
After applying environmental constraints to determine which
plant functional types (PFTs) may occur the model calculates
the "equilibrium" leaf area index (LAI) as the LAI that leads
to maximal net primary production (NPP). Competition between
plant functional types is simulated by using the optimal NPP
of each plant type as an index of competitiveness, with
additional rules to capture light competition. A two-layer
soil hydrology model also allows simulation of the competitive
balance between grass and woody vegetation including the
strong effects of soil texture. Model output consists of a
quantitative vegetation state description in terms of PFTs'
with their LAI and NPP.
The model has been constructed with an absolute minimum number
of calibration parameters allowing a wide range of data
sources to be used for validation including NDVI, global
vegetation maps and NPP measurements.

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VALIDATING TERRESTRIAL CARBON CYCLE MODELS THROUGH
OBSERVATIONS OF ATMOSPHERIC CO2 VARIATIONS: FIRST
RESULTS
OF A MODEL INTERCOMPARISON STUDY

Martin Heimann, EPRI-Carbon Cycle Model Linkage
Project
members

Max-Planck-Institut f1r Meteorologie,
Bundesstrasse 55, D-20146 Hamburg, Germany

The recent proliferation of global, high-resolution (0.5F8 x
0.5F8) models of the terrestrial biogeochemical cycling of
carbon demonstrates the need for new approaches of validating
the surface fluxes predicted by such models on regional,
continental and global scales.
Here we present the first results of study, in which six
different global terrestrial carbon cycle models are assessed
in how they predict the seasonal cycle of atmospheric CO2. To
this end we use a three-dimensional model of atmospheric
transport driven by monthly surface fluxes as predicted the
terrestrial models. In addition CO2 emissions from fossil fuel
use and monthly oceanic CO2 exchange fluxes calculated by the
Hamburg Model of the Ocean Carbon Cycle are specified as
surface fluxes. The simulated seasonal cycles are then com-

pared to the observations of the global atmospheric network of
monitoring stations maintained by the NOAA/CMDL program
[Convay et al., 1994].
Most of the five prognostic (i.e. climate data driven) models
included in the intercomparison predict in the northern
hemisphere a reasonably accurate seasonal cycle in terms of
amplitude and, to some extent, also with respect to phase. In
the Tropics, however, the prognostic models generally tend to
overpredict the net seasonal exchanges and thus lead to too
strong seasonal cycles as compared to the observations. This
result might be explained by a too strong sensitivity to
hydrological factors of the modelled processes in the tropical
regions. This is supported by means of sensitivity simulations
using the diagnostic model included in the intercomparison
study; a model which is based on satellite data to calculate
the seasonal uptake of CO2 by plants.
Reference:
Convay, T. J., P.Tans, L. S. Waterman, K. W. Thoning, D. R.
Buanerkitzis, K. A. Maserie and N. Zhang, 1994. Evidence for
interannual variability of the carbon cycle from the NOAA/CMDL
global air sampling network. J. Geophys. Res., 99D, 831-855.


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CONSTRAINING COMPREHENSIVE GLOBAL CARBON CYCLE
MODELS
ON THE SEASONAL TIMESCALE
THROUGH ATMOSPHERIC CARBON CYCLE TRACERS

M. Heimann1, K. Six1, W. Knorr1, C. D. Keeling2,
R. Keeling2, and M. Wahlen2

1Max-Planck-Institut f1r Meteorologie,
Bundesstrasse 55, D-20146 Hamburg, Germany

2Scripps Institution of Oceanography,
UCSD, La Jolla, CA 92093-0220, USA

The seasonal variation of atmospheric CO2 observed at any
particular location on the Earth represents a mixture of
several surface source and sink processes: photosynthesis and
heterotrophic respiration, fossil fuel CO2 emissions, biomass
burning, and seasonal exchanges with the oceans. Recent
high-precision data of CO2, its stable 13C/12C ratio and
concurrent measurements of O2/N2, however, provide a means to
disentangle this mixture and thus provide estimates seasonal
surface source fluxes on regional, continental and hemispheric
scales. Full use of the information content in these carbon
cycle tracers, however, requires comprehensive,
high-resolution models of the coupled ocean-

-atmosphere-landbiosphere carbon system. In this paper we show
how high-precision atmospheric carbon cycle tracer data from a
selected set of monitoring stations may help to discriminate
between several model formulations and thus provide a powerful
tool for the validation and the development of such models.

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#307 CONSTRAINTS ON THE GLOBAL CARBON CYCLE DERIVED FROM ATMOSPHERIC RADIOCARBON OBSERVATIONS

V. Hesshaimer and I. Levin

Institut fur Umweltphysik, University of Heidelberg INF 366, 69120 Heidelberg, Germany

The inventory of bomb 14C computed in a robust global carbon cycle model does not fit observations in the atmosphere and the oceans between 1955 and today. This mismatch reveals inconsistencies in the net exchange of radiocarbon between the troposphere and the other reservoirs when deduced from actual knowledge on global carbon cycling. We pointed out earlier three solutions to this problem within the stratosphere, the biosphere and the oceans [Hesshaimer et al., 1994, (Nature 370, 201-203)]. A reduction of the oceanic bomb 14C uptake by some 25% would solve the discrepancy, but contradicts the oceanic bomb 14C inventory compiled from the GEOSECS observations [Broecker et al., 1985 (JGR 90, 6953-6970)]. As the penetration of the bomb 14C into the non atmospheric reservoirs, particularly into the oceans, constrains their uptake rate of anthropogenic CO2, this inconsistency has to be solved.

To reduce the uncertainties on the non oceanic reservoir bomb 14C inventories, we now refined our previous analysis of the radiocarbon activity from the interannual to the seasonal time scale. Comparison between observed and modelled seasonal 14CO2 cycles in the northern and in the southern hemispheric troposphere from 1965 to present allows for supplementary constraints on the bomb radiocarbon burden of the stratosphere and the biosphere. We obtained information about the radiocarbon content and exchange time of the stratosphere from the tropospheric activity during about five years after the bomb peak maximum, when it is mainly influenced by seasonally variable input from the stratosphere. To achieve useful observational constraints upon the biosphere, we examined the delayed release of bomb radiocarbon stored through net primary productivity after the atmospheric nuclear weapon tests. First we compiled the strength of bomb perturbed biospheric 14CO2 respiration in a simple global carbon cycle inventory model to determine the interannual variations of this release. Then we refined these global biospheric 14CO2 fluxes with respect to their latitudinal and seasonal variability, and inserted them in a two dimensional atmospheric transport model to obtain a seasonally variable impact on the model atmosphere. Finally we determined global constraints on the biospheric carbon cycle by matching the model results with long term trend and seasonal cycle CO2 and (14CO2 observations at a set of atmospheric stations ranging from 83F8N to 71F8S.

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THE USA/NOAA PROGRAM OF GLOBAL MONITORING
OF CLIMATE FORCING
D. J. Hofmann

NOAA Climate Monitoring and Diagnostics Laboratory
325 Broadway, Boulder, CO 80303, USA

The U.S. National Oceanic and Atmospheric Administration has
been monitoring climate forcing agents (greenhouse gases,
aerosols and radiation) since the early 1970's. The record of
CO2 at Mauna Loa, on the island of Hawaii, when combined with
the early Keeling record begun during the International
Geophysical Year (IGY) in 1957, is now about 38 years in
length. The Climate Monitoring and Diagnostics Laboratory
(CMDL), which was formed in 1990, operates the baseline
stations of the former Global Monitoring for Climatic Change
(GMCC) program at Barrow, Alaska; Mauna Loa, Hawaii, American
Samoa; and the South Pole. Besides both flask samples and in
situ measurements of CO2, CH4, CO, N2O, and CFCs, recently
employed CFC replacements (HCFCs), ozone, aerosols and
radiation are also being monitored at these baseline sites. In
addition, a CMDL cooperative greenhouse gas flask sampling
network, which now involves over 40 sites plus shipboard
measurements, has been active since about 1980. More recently,
regional aerosol monitoring stations have been instituted to
study the possible role of anthropogenic aerosols in partially
masking greenhouse warming.
These data records indicate a number of interesting phenomena,
for example, the slowdown of CFC-11 and CFC-12 growth rates,
rapid increases in the HCFC replacements and large variations
in the global growth rate of some of the greenhouse gases.
Although the monitoring activity is important in its own
right, the mesh of flask sampling sites in the global network
and the data at hand are now adequate to allow analysis of
terrestrial and marine CO2 fluxes using global transport
models
and isotopic carbon measurements. These analyses are beginning
to reveal important information on global sources and sinks of
CO2 which will be useful for future climate change
assessments.

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QUANTITATIVE MODELING OF CARBON ISOTOPE DISTRIBUTION
IN THE OCEAN
M. Hofmann1, D. Wolf-Gladrow1, U. Riebesell1, K. Six2, E.
Maier-Reimer2
1Alfred-Wegener-Institut fuer Polar-und Meeresforschung
Am Handelshafen 12, 27570 Bremerhaven, Germany

2 Max Planck-Institut fuer Meteorologie
Bundesstrasse 55, 20146 Hamburg, Germany

The relative abundance of the stable C-isotopes 12C and 13C in
the dissolved inorganic carbon (EB13CDIC) and particular
organic
carbon (EB13CPOC) in the ocean shows a characteristic distri-

bution. Isotopic fractionation of carbon by phytoplankton is
an important process determining this distribution.
Variability in the EB13C of marine organic and inorganic matter
is frequently used as a proxy for the biological
productivity. Here we have applied the three dimensional
Hamburg Oceanic Carbon Cycle Circulation Model (HAMOCC) (E.
Maier-Reimer, 1993) combined with the biological model for
phyto- and zooplankton dynamics by K. Six (1994) to test the
suitability of three different parameterisations of
planktonic fractionation in reproducing the oceanic
distribution of EB13CDIC. Carbon isotopic fractionation was
included in the model by assuming 1) a constant fractionation of 20 permil,2) an empirical relationship between EB13CDIC and the
concentration of molecular CO2(aq) in the surface layer of the
ocean as observed by Rau et al. (1991),3) a mechanistic model of phytoplankton fractionation as
recently developed by Rau, Riebesell and Wolf-Gladrow, which
provides a microscopic understanding of the processes of
CO2-uptake and fractionation by phytoplankton described by a
diffusive CO2-transport through the water and the cell
membrane. Model results will be compared with field data of EB13CDIC.

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MECHANISMS OF TERRESTRIAL ECOSYSTEM FERTILIZATION
DURING THE HISTORICAL PERIOD: AN ANALYSIS USING THE
GLOCO GLOBAL CARBON CYCLING MODEL

R.J.M. Hudson1,2, S.A. Gherini2, A. Keller3,and R.A. Goldstein3
1Institute of Marine Sciences, University of California
Santa Cruz, CA 95064, USA
2Tetra Tech, Inc.
3746 Mt. Diablo Blvd. #300, Lafayette, CA 94549, USA
3Electric Power Research Institute
3412 Hillview, Palo Alto, CA 94304, USA
Matching the changes in terrestrial carbon storage implied
from land use change models and from deconvolution of the
atmospheric CO2 record using ocean models requires that some
fertilization of the terrestrial biosphere must have taken
place during the past century. Changes in CO2, climate, N
deposition, and forest management practices have been
suggested as possible causes of this apparent increase in
rates of forest growth and/or C storage in soils.
Understanding the relative importance of these mechanisms is
essential for projecting future changes in terrestrial carbon
storage. Here, we analyze how these mechanisms may have
affected changes in terrestrial carbon storage during the
historical period using the GLOCO global carbon cycling model.
The GLOCO model is an integrated, mechanistic model of the
ocean and terrestrial carbon cycles that includes
anthropogenic influences on the global C cycle through
scenarios for fossil fuel combustion, land use change,
forestry, and anthropogenic N emissions. The ocean carbon
cycle is adapted from a well-calibrated box-diffusion model
(HILDA). The terrestrial biosphere is simulated using a
seven-biome terrestrial ecosystem model that includes both C
and N cycling. Rates of fossil fuel emissions, land use
change, forest harvest, and environmental changes are taken
from the literature.
Our initial work with GLOCO indicated that anthropogenic N
emissions may have been a more significant contributor than
CO2
and temperature increases to the apparent fertilization of the
terrestrial biosphere over the last century. Other recent work
has suggested that climate change may have been the dominant
factor. In this paper, we reexamine our estimate of the extent
of N fertilization using a revised version of GLOCO that also
simulates the effects of precipitation on the productivity of
terrestrial ecosystems and on soil organic matter decay. We
also consider further the impact of N leaching from ecosystems
with high N inputs on the relationship between N emissions and
fertilization. We argue for the importance of simulating the
dynamics of changes in C and N storage in vegetation and soils
in calculating the response of terrestrial ecosystems to
transient changes in environmental factors rather than relying
on static correlations derived from empirical observations of
terrestrial ecosystems. Finally, we also consider several
questions important to modeling the terrestrial carbon cycle
at global scales. How can highly-aggregated, process models
best be derived from physiologically-based ecosystem models
and empirical data? Which data best constrain the modeling of
terrestrial carbon cycle dynamics at biosphere, biome, and
ecosystem levels? How do the spatial scales at which
terrestrial ecosystems are aggregated influence model results
and uncertainty?
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GLOBAL NET CARBON EXCHANGE AND INTRA-ANNUAL ATMOSPHERIC CO2
CONCENTRATIONS PREDICTED BY AN ECOSYSTEM PROCESS MODEL AND
THREE-DIMENSIONAL ATMOSPHERIC TRANSPORT MODEL

E. R. Hunt, Jr.1, S. C. Piper2, R. Nemani1, C. D. Keeling2,
R. Otto2, and S. W. Running1

1School of Forestry, University of Montana, Missoula, MT
59812-1063, USA

2Scripps Institution of Oceanography, La Jolla, CA 92093-0220,
USA

A generalized terrestrial ecosystem process model, BIOME-BGC,
was used to simulate the global fluxes of transpiration,
photosynthesis (PSN), autotrophic respiration (Ra), and
heterotrophic respiration (Rh). In contrast with other
ecosystem models, the daily fluxes from BIOME-BGC are more
controlled by water balance rather than by net N mineralized.
Seven land cover types were defined based on principals of
ecology and remote sensing: 1) C3 grasslands, 2) C4
grasslands, 3) evergreen broadleaf forests, 4) deciduous
broadleaf forests, 5) evergreen needleleaf forests, 6)
deciduous needleleaf forests, and 7) shrublands. To estimate
actual land cover types for each grid cell, we used Matthews
potential vegetation and percent agriculture databases; when
the percent agricultural cover was 50% or greater, we assigned
the land cover type to be either C4 or C3 grasslands. Daily
meterological data and normalized difference vegetation index
(NDVI) for the year 1987, both gridded to 1x latitude by 1x
longitude, were used to drive model simulations. From maximum
NDVI, annual maximum leaf area index (LAI) for each grid cell
was estimated using separate regressions for grasslands,
broadleaf and needleleaf cover types.
Global net primary production (NPP) was estimated to be 52 Pg
C for the year 1987. This net is the difference of 111 Pg C
PSN and 59 Pg C Ra. Global annual Rh was estimated to be 66 Pg
C. Whereas neither of these estimates are probably the true
values for 1987, we have more confidence in NPP compared to
Rh, as BIOME-BGC predicts the stable carbon isotopic ratio of
vegetation, which is a function of water use efficiency.
Global precipitation, climate, and water use effiency place an
upper bound on global PSN, and hence NPP, because
transpiration and carbon fluxes are independently calculated.
As global NPP is about equal to heterotrophic respiration, we
reduced heterotrophic respiration by 52/66 for each grid cell,
and used the daily carbon fluxes as inputs to a
three-dimensional atmospheric transport model, which uses grid
cells of 8x latitude by 10x longitude. We then compared
predicted atmospheric CO2 concentrations with actual CO2
concentrations for 1987 from various monitoring stations. The
predicted and measured compared reasonably well for the
northern hemisphere, with the largest difference of 7 PPM for
Point Barrow. Predictions for the southern hemisphere were
considerably off because of large fluxes of heterotrophic
respiration during the dry season. Analyses of intra-annual
variations of NDVI, precipitation and NPP indicated areas of
disagreement. Generally gridcells with evergreen foliage and a
dry season indicated NDVI did not estimate NPP well, and
BIOME-BGC results were unreasonable in coastal areas.

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MONITORING OF OZONE USING LASER HETERODYNE SYSTEM OVER ANTARCTICA

S.L. Jain and B.C. Arya

Radio Science Division, National Physical Laboratory, New Delhi-110012

The study of minor constituents in the atmosphere is of paramount interest to understand the structure of stratosphere and troposphere. In the window region 9-11 m a large number of atmospheric species have characteristic absorption lines which can be completely resolved with laser heterodyne system due to its ultra high quantum detection efficiency and high spectral resolution. In view of the above a laser heterodyne system using a tunable infrared CO2 laser and one GHz Acousto- Optic Spectrometer (AOS) as its back end has been designed, developed and fabricated at National Physical Laboratory, New Delhi, to monitor various trace species in the stratosphere and troposphere over Antarctica. The CO2 laser is tuned on the absorption line of constituent to be measured and mixed with solar radiation. The beat frequency (RF) after proper amplification is fed to acousto- optic spectrometer. The AOS employs an Bragg cell which serves the key role of converting RF signals to ultrasonic traveling waves modulating the optical index of the cell. The cell is illuminated across its aperture by an another diode laser (784 nm). A fraction of light is diffracted by acoustic waves, the angle of diffraction is determined by the RF input frequency while the intensity of the diffracted light is proportional to the power of the input RF signal. The intensity distribution can be detected by a CCD array which in turn represents the required RF power spectrum. The data thus obtained are inverted to get vertical profiles of minor constituents including those of ozone using inversion technique developed by one of the author(Jain, S.L.). This system has been successfully set up at Maitri an Indian Antarctic station (700 46' S, 110 44'E) during 1993-1994 and also again during 1994-1995 Antarctic summer. This is first of its kind over Antarctic region. In the present communication some salient features of laser heterodyne system with acousto-optic spectrometer and results obtained are discussed in detail.

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A MODELING APROACH TO LINKAGE BETWEEN PHYSICAL AND
BIOGEOCHEMICAL PROCESSES AT LAND SURFACE

J. Ji and Y. Hu

Institute of Atmospheric Physics,
Chinese Academy of Sciences, Beijing 10029, China

Based on a feedback mechanism between phusiological growth
process of plant and abiotic environment-soil and the
atmosphere, a modeling approach to linking physical and
biogeochemical processes at land surface is proposed by
coupling a plant growth model with a SVAT- type model, LPM.For
the sake of consistancy with the temporal and spatial scales
and the hierarchy of current climate model, the modeling is
focused on mature ecosystem and on annual and decadal scales.
It is assumed that the structure and functions of biome are
stable and in balance with abiotic environment-soil and
climate. The Land surface Process Model (LPM) involves
physical transfer processes of radiation, heat, water vapor
and momentum between soil, vegetation and the atmosphere. In
plant growth model, the living vegetation is consist of three
main biomass components: leaf, stem and root, and the dead
vegetation: a litter layer is also included, and leaf
photosynthesis, respiration of organs, allocation of dry
matter among the bionass components and decomposition of
organic matter are taken into consideration. All physiological
processes are affected by PAR, CO2 in the atmosphere, air
temperature and moirture, and soil and canopy temperature and
moisture predicted by LPM. With the growth of plant, changes
in leaf area index, root density and the other morphological
parameters change physical parameters of vegetation (albedo,
roughness, resistance...). hence, influence significantly the
strength and direction of physical processes (energy and
material exchanges) at land surface.

The modeling approach, called Atmosphere-Vegetation
Interaction Model (AVIM), can be directly linked with climatic
model through energy and material exchanges. It has been
applied to temperate forest ecosystem in Northeastern China
and agricultural ecosysytem- winter wheat in Northern China.
The annual variations of energy, material (water, CO2)
exchanges at the surface and biomass of biomes are simulated
well.


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THE STUDIES OF COUPLED OCEAN-ATMOSPHERE
MODELLING GLOBAL CLIMATE CHANGES


Dayong Jiang1, Yimin Liu2, Yan Luo2, Youlong Xia3

1Chinese Academy of Meteorological Sciences, Beijing
100081,
P.R. China

2Chinese National Climate Center, Beijing 100081, P.R.
China

3Chinese Institute of Meteorology, Beijing 100081, P.R.
China

OBSERVATIONAL STUDIES (DATA ANALYSIS). The COADS data are used
to describe the longitude-time evolution of monthly average
of SST (and U.OLR.SSTA) along equator in Pacific from 1950 to
1987. The dominant feature is the annual and interannual
variation of the equatorial cold tongue in the east-central
Pacific. In the western Pacific and Indonesian maritime
region, a warm pool of water exceeding 29F8C may be found at
all seasons. The most prominent climate signal in the tropics
on interannual time scales is the ENSO phenomenon during the
period that anomalous warm surface water appears for a number
of months in the central and eastern tropical Pacific. It is
revealed that the ENSO event is the result of large scale
interaction of coupled air-sea system. Thus the numerical
simulation studies must be done according to the coupled
ocean-atmosphere models (CGCMs).

SIMULATION STUDIES. Several CGCMs are improved and developed.
1. The basic mechanism of CGCMs. From the equations of
CGCMs-1 we know that atmosphere is influenced by ocean
with latent heat and current, and in turn, ocean is
influenced by atmosphere with wind stress.
2. Research of seasonal SST evolution (one of difficult
problems). We design CGCMs-2 besides including the basic
mechanism, also including three kinds of thermodynamic
processes. Integrating for three months to get SST fields
and then comparing that with the observations, we can see
that the domain, position, and shape of weat Pacific warm
pool and slow oscillation of 28F8 SST isotherm are
simulated excellently.
3. The simulation of ENSO event. CGCMs-3 is similar to LDGO
model. Figure 3a is the observed wind anomalies in
December 1982, figure 3b is the result simulated by AGCM
in CGCMs-3. The main features in the two figures are very
similar.
4. Surface heat budget (another difficult problem). CGCMs-4
is improved atmosphere model of CGCMs-3. According to
baroclinity of the tropical upper ocean, if there is
nonhomogeneous temperature distribution somewhere, the
ocean surface certainly occurs a dip that leads to
vertical variation of the horizontal pressure gradient
with height. While vertical variation ocean current with
height appears, the thermal current occurs, which
represents shear of upper layer and lower layer. The
current variation with height is caused by sea
temperature heterogeneity of isobaric level. After intro-
ducing the thermal current to coupled air-sea system, we
have improved the diabatic heating process of atmosphere
model in LDGO.


>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

POSITIVE AND NEGATIVE EFFECTS OF GLOBAL CLIMATE CHANGE
ON SOYBEAN PRODUCTION IN CHINA

Z.Q. Jin, T.Y. Chou, D.K. Ge, H. Chen and X.L. Zheng

Jiangsu Academy of Agricultural Sciences, Nanjing 210014, PR
China
Feng Chia University, Taichung, Taiwan

Using an approach to link the SOYGRO model with 3 doubled CO2
climate change scenarios derived from the GISS, GFDL and UKMO
equilibrium GCMs, the potential effects of global climate
change on soybean production in 3 main soybean producing areas
of China were assessed. Before assessment, agronomic data and
daily weather data for more than 3 successive years were
collected from 13 representative sites to validate and
calibrate the SOYGRO for examining its suitability in the
studied region. Genetic coefficients for the local cultivars
used were determined, by trial and error. Sensitivities of the
SOYGRO to changed climatic conditions were also analyzed. The
results showed that there exists a good agreement between the
simulated and observed yields and, the SOYGRO is reasonable as
a powerful tool being used in this impact study. Then the
SOYGRO model was run again for the same locations for 20 to 30
years, with the local climatic data and the doubled CO2
climate
change scenarios.

Evapotranspiration ratio was used to evaluate change in
moisture status during soybean growing season. A thermal index
was adopted to estimate movement of the northern limit for
summer-sowing soybean and an empirical formula was employed to
assess the effects of climate change on soybean quality.
Limitations of the SOYGRO used in this study were also
discussed.
The final results are listed as follows:1) Under the 3 climate change scenarios without considering
CO2
physiological effects, increase in temperature seems to be
beneficial to irrigated soybean yields in the most northern
part of the studied region, where cold injury is the main
limiting factor for soybean crop at present, but unfavorable
in the rest areas, especially in the middle and lower Valley
of the Yangtze River.
2) Without considering CO2 direct physiological effects in
some
high latitude sites where the projected climate would become
arid, good irrigation condition might increase rainfed soybean
yield. In the lower latitude areas, however, irrigation might
only alleviate in some extent, but could not compensate the
nagative effects due to increase in temperature.
3) If considering climate change combined with the CO2 direct
effects on soybean photosynthesis and evapotranspiration
(CC+PE), the yields simulated both of rainfed and irrigated
soybean would significantly increase in the Northeast and the
North China plains, but only lightly increase, even decrease
in the Middle and Lower Reaches of the Yangtze River. The
northern limit for summer-sowing soybean would be extended
northward about 3-5 degrees of latitude, depending on the
climate scenario used.
4) Under all climate change scenarios studied, the water
demand (WD) for soybean would obviously increase in the
Northeast China Plain and the North China Plain, but decrease
in the Middle and Lower Valley of the Yangtze River. If
considering (CC+PE), the WD in most sites further increases,
because enlarged leaf area index might require more irrigation
water.For soybean crop, increase in WUE mainly results from
the increased yields.
5) Large increase in temperature might result in reduction of
soybean quality in some aspects, such as decrease in oil
content and iodine value, but protein content would increase.
Considering soybean being a major source of plant protein,
increase in protein content will be advantageous for food
structure amelioration in China.
In summary, global climate change seems to be beneficial to
soybean production in northern China, but more disadvantageous
in the Middle and Lower Valley of the Yangtze River.
Considering the former being the main soybean producing area
in China, it might be concluded that the effects of global
climate change on soybean production in China is more positive
and less negative.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


GLOBAL ISENTROPIC MODELING AND PERSPECTIVES OF
HYDROLOGIC
AND BIOGEOCHEMICAL PROCESSES RELEVANT TO CLIMATE
CHANGE

Donald R. Johnson, Tom Zapotocny, Philip
Politowicz,
Allen Lenzen, Todd Schaack, Fred Reames and Zhuojian
Yuan

Space Science and Engineering Center
University of Wisconsin, Madison, WI USA

A series of global simulations based on isentropic modeling of
hydrologic processes and long range trace constituent
transport have established a remarkable fidelity for the
conservation of the joint distributions of potential
vorticity, water substances and other trace constituents
relative to modeling in sigma coordinates. By virtue of
atmospheric stratification in combination with amplifying
baroclinic waves, the isentropic structure of trace
constituents is characterized by relatively large horizontal
scales and relatively thin laminar structure with strong
vertical gradients. The use of isentropic models to simulate
long range transport of water substances (vapor-liquid-ice),
chemical constituents, aerosols, etc. avoids excessive
vertical numerical dispersion that is prevalent in sigma model
simulations of baroclinic exchange processes.
Seasonal global simulations with the UW hybrid and sigma
coordinate models of long range transport of hydrologic,
chemical and aerosol constituents will illustrate the fidelity
of isentropic models to simulate clouds, cloud-radiative
interaction, and biogeochemical processes involving exchange
in relation to the atmosphere s hydrologic cycle. These
simulations will be discussed within a perspective of climate
change in relation to atmospheric differential heating, mass,
energy, and entropy exchange and planetary scale transport of
trace constituents relative to global monsoonal circulations.
Drawing on theoretical models of turbulent diffusion of scalar
properties and global simulations with idealized constituent
distributions, preliminary results concerning the limits of
climate predictability imposed by spurious numerical
dispersion of joint distributions of trace constituents will
be offered.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


INTERCOMPARISON OF SIMULATIONS OF THE MONSOON CLIMATE
AND
VEGETATION OF AFRICA AT 6000 yr B.P. USING POLLEN AND
LAKE
DATA

D. Jolly1, F. Laarif2, S.P. Harrison2, B. Damnati2
and R.
Bonnefille3

1Global Systems Group, Department of Ecology, Lund
University,
Ekology Building, S-223 62 Lund, Sweden

2Dynamic Palaeoclimatology Group, Department of
Physical
Geography, Lund University,
Slvegatan 13, S-223 62 Lund, Sweden

3Laboratoire de Gologie du Quaternaire du CNRS,
CEREGE, BP 80,
F-135 45 Aix-en-Provence Cdex 04, France.

Pollen-based biome reconstructions and geological records of
lake level at 6000 yr B.P. indicate conditions considerably
wetter than today across northern Africa, as far north as
21F8N. The data show a tendency towards more arid conditions
than today in the equatorial zone, particularly in
Central-East Africa. These patterns can be interpreted as
showing a major expansion of the Afro-Asian monsoon,
associated with a more northerly position of the ITCZ in
summer. These pollen-based biome reconstructions and lake
level data provide a benchmark against which to assess
simulations of the climate of Africa at 6000 yr B.P.
Climate model simulations of 6000 yr B.P. have been made by
several modelling groups within the framework of the
Paleoclimate Modelling Intercomparison Project (PMIP). To
facilitate comparisons with the pollen-based biome
reconstructions, we have used output from these simulations to
drive the BIOME model, which predicts the equilibrium
distribution of vegetation types as a function of climate. The
lake data are compared with simulated precipitation minus
evaporation (P-E).

The climate models show an expansion of the African monsoon,
expressed as an increase in P-E and a northward shift in
moisture-demanding biomes (xerophytic woods/scrub and warm
grass/shrub) at the southern margin of the Sahara. The
amplitude of this shift varies among models, however
comparisons with the pollen and lake data show that the models
significantly underestimate the northward expansion of the
monsoon by between 6F8 and 10F8 of latitude. This result
suggests that the models are missing a positive feedback. A
6000 yr B.P. simulation with the NCAR CCM1 model, coupled to a
mixed-layer ocean (J.E. Kutzbach, in prep.) shows an expansion
of the African monsoon in eastern Africa that is closer to the
observations but still fails to capture the increase in P-E
indicated by the data from West Africa. Additional feedbacks,
related e.g. to vegetation-induced changes in albedo or to the
presence of more extensive lakes and wetlands, may be
necessary to explain the observed patterns of climate changes
at 6000 yr B.P.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


ESTIMATING NET-FLUXES OF CARBON BETWEEN
ATMOSPHERE AND BIOSPHERE: A MONTE CARLO SIMULATION
USING ATMOSPHERIC CO2 and 13CO2 OBSERVATIONS

F. Joos, M. Bruno

Climate and Environmental Physics, Physical Institute,
University of Bern, SidlerstraE1e 5, CH-3012 Bern, Switzerland

Program in Atmospheric and Oceanic Sciences, Princeton
University,
Princeton, NJ, USA


Understanding the distribution of anthropogenic CO2 in the
climate system and the processes which govern the carbon
exchange between the atmosphere and other carbon reservoirs is
a prerequisite to establish the relationship between future
emissions and atmospheric CO2 levels, and thus to estimate the
potential range of future climate change. In the presentation,
a short overview of the current understanding of atmospheric
CO2 variations during the last millennium will be given.
Furthermore, two different estimates of historical carbon
fluxes between atmosphere and biosphere as obtained by a model
analysis of atmospheric CO2 and 13CO2 observations will be
presented.The uncertainties of the estimated fluxes due to uncertainties
in the atmospheric observations are analyzed using a Monte
Carlo technique. Uncertainties due to model parameters are
calculated using error propagation.

Building on most recent ice core and atmospheric CO2 data, we
update earlier simulations using the conventional (single)
deconvolution approach. Atmospheric CO2 is prescribed in the
Bern global carbon cycle model (HILDA) according to
observations. The oceanic uptake of carbon is calculated using
the HILDA model. The net-exchange between atmosphere and
biosphere is then obtained by subtracting estimated fossil
emissions from the combined change in modeled oceanic and
observed atmospheric carbon inventories. In agreement with
earlier results, a biospheric source of order 1Gt-C yr-1 is
found for the nineteenth century. After 1930, the biosphere
acted as a small carbon sink.

As a second approach, we prescribe in the HILDA model
atmospheric CO2 concentrations as well as atmospheric 13CO2
observations (Simple ice core data + atmospheric
observations). Isotopic fractionation between atmosphere and
ocean and atmosphere and biosphere are different. This allows
to discriminate fluxes between atmosphere and ocean from those
between atmosphere and biosphere. The carbon uptake by
biosphere and ocean is calculated in the model, such as to fit
both, the atmospheric CO2 and 13CO2 data (double
deconvolution).
We found in agreement with the single deconvolution that the
biosphere acted as a source between 1800 and 1950, and as a
carbon sink afterwards. Error analysis shows that single and
double deconvolution yield independent results, though the
same carbon cycle model is used. For the double deconvolution,
estimates of biospheric fluxes are sensitive to changes in
model parameters for the last period of the record
(1950-1990), whereas for the period 1800-1950 potential errors
due to uncertainties in the model parameters are relatively
small.

Until 1930, our results agree with independent estimates of
carbon fluxes due to deforestation and land use changes based
on statistics. After 1930, our analysis suggest a modest net
biospheric sink (or source), whereas estimates of
deforestation fluxes based on statistics give a substantial
carbon release into the atmosphere.

MODELLING SOUTHERN AFRICAN CIRCULATION VARIABILITY
OVER THE 1979-1988 AMIP PERIOD

A. M. Joubert and P.D. Tyson

Climatology Research Group, University of the Witwatersrand,
P.O. Wits, 2050, South Africa


Assessment of the performance of a range of general
circulation models in simulating both global and regional
climate has historically been hampered by differences in
experimental and model design. The Atmospheric Model
Intercomparison Project (AMIP) addresses the need for a
comprehensive intercomparison of climate models. All modelling
groups participating in AMIP provide a simulation of global
climate for the 1979-1988 decade. Each AMIP run is initialised
using common boundary forcings which include observed climato-

logically-varying sea-surface temperatures and sea-ice
distributions. The southern African diagnostic subproject of
AMIP aims to provide an analysis of simulated Southern Hemi-

sphere circulation features which directly influence the
climate of southern Africa. In this paper, the simulation of
several features of the mean mass distribution in the Southern
Hemisphere is assessed. In addition, the simulated atmospheric
response in the southern African region to tropical Pacific
sea-surface temperature anomalies is also investigated.

Monthly means of sea level pressure, geopotential height and
zonal wind simulated by four models (ECMWF, UKMO, NCAR and
CSIRO) are considered. In general, the higher the spatial
resolution of the four models, the better the simulation of
Southern Hemisphere circulation features. The meridional
pressure gradient at sea level is shown to be well reproduced,
as is the strength and seasonal position of the circumpolar
trough. The improvement in the simulation of the trough leads
to an improved simulation of the semi-annual cycle in sea
level pressure. The westerly wind maximum at 200 hPa is
simulated accurately although the split jet structure in the
New Zealand sector in winter is less successfully modelled.
The zonally-asymmetrical component of the flow at 500 hPa,
which is dominated by wave 1, is better simulated by the
higher resolution models. The improvement is most marked in
winter, when both the simulated phase reversal at
approximately 40F8S and the position of the ridge in the
midlatitudes, as well as the amplitude of wave 1 are in close
agreement with observations.

In the region of southern Africa, the westerly flow at 500 hPa
is known to undergo marked changes in response to sea-surface
temperature anomalies in the central Pacific Ocean. During
ENSO years, modulation of the position of westerly waves at
500 hPa contributes to below-average rains over much of the
southern subcontinent. During mid-summer, the models may
overestimate barotropicity over subtropical southern Africa,
with westerly wave activity displaced well to the south of the
subcontinent. In large measure, however, the AMIP simulations
considered to date reproduce adequately the gross features of
500 hPa circulation adjustments, and provide some confidence
in the ability of the models to simulate interannual
circulation variability over the southern African region.


>>>>>>>>>>>>>>>>>>>>>>>>>>>

TREE-RING SEQUENCES, SNAIL SHELL, AND ISOTOPIC RECORDSAT THE YD/PB BOUNDARY

K.F.Kaiser1, B.Kromer2, B.Becker3,G.Bonani4, D.Muller5, M.Spurk6, N.Thew7, P.Trimborn8
1Swiss Federal Institute for Forest, Snow & Landscape Research,
CH-8903 Birmensdorf

2Institute of Environmental Physics, Heidelberg Academy of
Science, D-69120 Heidelberg

3Institute of Botany, University of Hohenheim, D-70599
Stuttgart

4Institute of Particle Physics, FIT, CH-8093 Zurich

5Wolfganghof 13a, CH-9014 St.Gallen

6Institute of Botany, University of Hohenheim, D-70599
Stuttgart

7Cantonal Archeological Service, CH-2007 Neuchachtel

8GSF-Research Center, Institute of Hydrology, D-85764
OberschleiE1heim

The German oak chronology from Central Europe reaches back to
almost 10,000 B.P. The German Preboreal pine chronology
overlaps with the oak series over two 14C centuries and
presently spans 1920 rings. All trees have been collected from
alluvial deposits in the flood plains of Danube, Rhine and
Main and are not classified in a general stratigraphical
order. Both sequences have been matched by dendrochronology
and 14C wiggles (Becker & Kromer 1993); however, the link must
still be regarded as tentative, since the low replication of
the series at either end does not permit statistical tests.
High-precision 14C analyses have been applied on both series.
Those of the pines provide a calibration curve from 11,600 to
9700 cal B.P. (10,150 to 8750 B.P.). Three major 14C anomalies
are identified at 10,100, 9600, and 8800 B.P. Preboreal pine
chronologies from four sites in the area of Zurich
(Switzerland) are all floating. In contrast to those from
Germany they are derived from in situ stumps embedded in loamy
alluvial deposits. Tree-ring series of the chronologies from
Birmensdorf and Friesen berg have been dated by AMS. The
Birmensdorf sequence is synchronous to the second part of the
10,100 14C anomaly and that from Friesenberg to the plateau of
9600 B.P. (Kaiser 1993). At site KHWiedikon along a 6.76m
profile a snail shell record parallel to the pine stumps was
recovered. The pines form a major and four partial
chronologies (Kaiser 1994). AMS age determinations on plant
remains extracted with the snail shells range from 10,600 to
9100 B.P.

2H and 13C time series have been investigated from the
tree-ring cellulose in the German pine chronology. The stable
isotopes are expected to reveal climatic information (rel.
humidity of the growing season) about the climatic change at
the YD/PB transition. In contrast to other finds this seems
not to happen abruptly, but rather covers c. two centuries
(Becker et al. 1991). The stable isotope ratios d13C, d18O in
the shells of land snails contain climatic infor mation too
(Kaiser & Eicher 1987). Preliminary results display some
variations as the Friesland oscillation but not yet, at time
of printing, satisfying evidence for the YD/PB transition. All
chronologies from Switzerland have been crossdated with the
German Preboreal pine chronology. This fact rises the
dendrochronological evidence, assigns absolute dates to the
Swiss chronologies and links the German Preboreal chronology
with chronostratigraphy.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


MODEL RECONSTRUCTION OF SEASONAL AND LATITUDINAL
VARIATIONS OF THE ZONALLY AVERAGED
STRATOSPHERIC COMPOSITION AND AIR TRANSPOR TDURING
THE LAST GLACIAL AND PREINDUSTRIAL PERIODS

I.L. Karol1, Ch. Bruhl2, P.J. Crutzen2, Ye. E. Ozolin1,
E.V. Rozanov1, A. Zieger2, V.A. Zubov1

Main Geophysical Observatory, St. Petersburg, 194018, Russia

2Atm. Chemistry Department, Max Planck Institute for Chemistry,
D-55020 Mainz, Germany

Two-dimensional atmospheric model of photochemical, radiative
and dynamical processes and their interactions in the global
layer up to 66 km (step 2 km) level and from the pole to pole
(step 10 deg.) is used for reconstructions of trace gas
concentration distributions for period of 1980; for
preindustrial period of 1850 and for last glacial period of 18
ky B.P., based on the recent measurements of CO2 , CH4 and N2O
content in Antarctic and Greenland ice core air, which are
extrapolated to other latitudes. The surface air temperature,
radiative properties of the Earth's surface are taken from the
published paleoclimatic reconstructions. The model sensitivity
to possible large variations of CO and NOx surface sources
intensities to variations of tropospheric temperature and
humidity in the considered period is studied and found that
stratospheric composition and dynamics are few sensitive to
these. The considerable reduction of greenhouse gas content
and moisture in the atmosphere of the period leads to the
warming of the middle and upper stratosphere. This temperature
change caused the increase of stratospheric air transport rate
in the meridional plane during the equinoxes and its reduction
at the solstices. Ozone mixing ratio drops to 10-12 ppbv in
the lower troposphere and increases to 6.0-7.5 ppmv in 40-46
km layer, but in the 20-30 km layer it remains almost the same
as in preindustrial and in 1990 periods. The annually averaged
total ozone is conserved for all these periods.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


A SYSTEM MODEL OF GLOBAL OZONE CONTROL AND PROTECTION

I.L. Karol

Main Geophysical Observatory, St. Petersburg, 194018, Russia


(unavailable)

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

INTERPRETATION OF SEASONAL, BIENNIAL, DECADAL,
AND SECULAR CHANGES IN THE ATMOSPHERIC CO2

C.D. Keeling, R.B. Bacastow, and T.P. Whorf

Scripps Institution of Oceanography
La Jolla, CA 92093-0220, U.S.A.


The longest records of atmospheric CO2 concentration now
extend to 37 years.These data reveal that the global carbon
cycle produces signals in atmospheric CO2 on almost all time
scales that can be analyzed. The seasonal cycle of atmospheric
CO2 in the northern hemisphere, which predominantly reflects
changes in the growth and decay of terrestrial plants, has
varied in both amplitude and phase. The largest signals are
associated with pulses of warming which peaked in 1981 and
1990, but in the arctic a biennial signal also correlates with
temperature. In addition the amplitude has increased overall
by 20% at Hawaii and 40% at Point Barrow, Alaska, and the
phase has advanced by 7 days at both sites since the early
1960's. Although similar changes on short time scales probably
took place in earlier times, it seems likely that the overall
changes are a result of unusually rapid warming over the past
30 years, especially at high latitudes.

Moreover the decadal signal shows approximately a two year lag
in CO2 response to temperature change. This fact may explain a
puzzling feature of the decadal signal in CO2 concentration at
Hawaii which is coherent with the average northern hemisphere
temperature with only a small phase lag, when one might expect
a priori that the rate of change of concentration would be
nearly in phase with temperature change. During periods of
warming, the rate of assimilation of CO2 increases but with a
delay of about two years, thus approximately 1/4 of the
decadal cycle period. The change in concentration in turn lags
the assimilation flux signal by another 1/4 of a cycle so that
the decadal terrestrial signal of CO2 assimilation is
approximately 180 degrees out of phase with temperature. When
an oceanic signal caused by warming and cooling of surface sea
water is also allowed for in the analysis, it becomes possible
to estimate the rate of terrestrial sequestration of carbon
associated with decadal change, in spite of phase lags.

In the southern hemisphere, the terrestrial seasonal signal is
much weaker and not yet clearly separated from an oceanic
signal by any modeling simulations that we are aware of.
Nevertheless, a large increase in the amplitude of the
seasonal cycle at the South Pole in 38 years suggests that
seasonal plant growth and decay has also changed in the
southern hemisphere.
The decadal signal in concentration at the South Pole is
similar to that at Hawaii, perhaps indicating a sequestration
signal in the southern hemisphere, but interhemispheric mixing
of the atmosphere on the decadal time scale obscures the
location of the terrestrial signal, which may be mainly in the
northern hemisphere. The presence of these seasonal, biennial,
and decadal signals in atmospheric CO2 linked to variations in
climatic parameters, offers a valuable testing ground for
terrestrial carbon cycle models, if these are devised so that
they can be forced by real time data rather than climatic
averages.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

INTERPRETATION OF SEASONAL, BIENNIAL, DECADAL, AND SECULAR CHANGES IN THE ATMOSPHERIC CO2

C.D. Keeling, R.B. Bacastow, and T.P. Whorf

Scripps Institution of Oceanography La Jolla, CA 92093-0220, U.S.A.

The longest records of atmospheric CO2 concentration now extend to 37 years.These data reveal that the global carbon cycle produces signals in atmospheric CO2 on almost all time scales that can be analyzed. The seasonal cycle of atmospheric CO2 in the northern hemisphere, which predominantly reflects changes in the growth and decay of terrestrial plants, has varied in both amplitude and phase. The largest signals are associated with pulses of warming which peaked in 1981 and 1990, but in the arctic a biennial signal also correlates with temperature. In addition the amplitude has increased overall by 20% at Hawaii and 40% at Point Barrow, Alaska, and the phase has advanced by 7 days at both sites since the early 1960's. Although similar changes on short time scales probably took place in earlier times, it seems likely that the overall changes are a result of unusually rapid warming over the past 30 years, especially at high latitudes.

Moreover the decadal signal shows approximately a two year lag in CO2 response to temperature change. This fact may explain a puzzling feature of the decadal signal in CO2 concentration at Hawaii which is coherent with the average northern hemisphere temperature with only a small phase lag, when one might expect a priori that the rate of change of concentration would be nearly in phase with temperature change. During periods of warming, the rate of assimilation of CO2 increases but with a delay of about two years, thus approximately 1/4 of the decadal cycle period. The change in concentration in turn lags the assimilation flux signal by another 1/4 of a cycle so that the decadal terrestrial signal of CO2 assimilation is approximately 180 degrees out of phase with temperature. When an oceanic signal caused by warming and cooling of surface sea water is also allowed for in the analysis, it becomes possible to estimate the rate of terrestrial sequestration of carbon associated with decadal change, in spite of phase lags.

In the southern hemisphere, the terrestrial seasonal signal is much weaker and not yet clearly separated from an oceanic signal by any modeling simulations that we are aware of. Nevertheless, a large increase in the amplitude of the seasonal cycle at the South Pole in 38 years suggests that seasonal plant growth and decay has also changed in the southern hemisphere. The decadal signal in concentration at the South Pole is similar to that at Hawaii, perhaps indicating a sequestration signal in the southern hemisphere, but interhemispheric mixing of the atmosphere on the decadal time scale obscures the location of the terrestrial signal, which may be mainly in the northern hemisphere. The presence of these seasonal, biennial, and decadal signals in atmospheric CO2 linked to variations in climatic parameters, offers a valuable testing ground for terrestrial carbon cycle models, if these are devised so that they can be forced by real time data rather than climatic averages.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

A MODEL OF GLOBAL SCALE LAI AND PHOTOSYNTHESIS,
COMPARISON WITH REMOTELY SENSED PAR
ABSORPTION EFFICIENCY AND PHOTOSYTHESIS

L. Kergoat1, A. Ruimy2, P. Maisongrande1, G. Dedieu1 and B.
Saugier3
1CESBIO, 18 av E.Belin, bpi 2801, 31055 Toulouse cedex, France
2Carnegie Institution of Washington, Department of Plant
Biology,
290 Panama Street, Stanford, CA 94305, USA

3Laboratoire d'Ecologie Vegetale, Bat. 362, Universite de Paris
Sud,
91405 Orsay Cedex, France


In the context of rising atmospheric CO2 and global climate
change, it is of particular importance to be able to develop
prognostic, process-based models that can be used to predict
the functioning of terrestrial vegetation in a changing
environment. One key variable of this type of model is the
leaf area index (or LAI), which determines the potential of
terrestrial vegetation to absorb photosynthetically active
radiation (PAR) and use it to drive photosynthesis.
Resource-based approaches are particularly interesting if one
wants to model the behaviour of vegetation in a context of
changing resources, such as CO2 and water availability.

This study presents a model based on an equilibrium-LAI
assumption, which states that canopy development is
constrained by soil water availability: the canopy develops,
thus increasing the evapotranspiration losses, until a
critical water stress is reached. Coupled photosynthesis and
evapotranspiration are simulated using monthly climate
forcings (precipitation, temperature, solar radiation) and an
integration of leaf-level responses to the canopy level.Remotely sensed vegetation indices have been widely used to
estimate variations in the absorption efficiency of PAR by
terrestrial vegetation in the contemporary era, and can be
used as a reference for our estimation of LAI. A comparison
with absorption efficiency derived from a NOAA-AVHRR
normalized difference vegetation index (NDVI) shows that the
major part of the spatial variability in absorption efficiency
is reproduced by the LAI-water resource equilibrium
hypothesis. The comparison also shows the limitations of this
hypothesis for certain biomes.Photosynthesis can also be estimated from remotely-sensed
absorption efficiency and incoming solar radiation data, in a
diagnostic, parametric-type model. The estimates of photo-

synthesis using the process- based and parametric models
developed in this study are compared. The interannual variabi-

lity in photosynthesis, due to interannual climate variability
in the case of the process model, and to interannual
variations in NDVI in the case of the parametric model, is
compared and discussed.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


DYNAMICS OF METHANE EMISSIONS IN A BOREAL PEATLAND

A. Kettunen1, V. Kaitala1, J. Alm2, J. Silvola2, H. Nykdnen3,
and P. J. Martikainen3

1Systems Analysis Laboratory, Helsinki University of TechnologyOtakaari 1 M, FIN-02150 Espoo, Finland

2Department of Biology, University of Joensuu
P.O. Box 111, FIN-80101 Joensuu, Finland

3Department of Environmental Microbiology, National Public
Health Institute
P.O. Box 95, FIN-70701 Kuopio, Finland

The high latitude northern peatlands, acting as methane
source, contribute to climate change. High temporal and
spatial variations in the methane fluxes from peatlands are
related to variations in environmental factors. Here, the
effects of temperature, precipitation and depth of the water
table on the methane flux from a boreal low-sedge Sphagnum
papillosum pine fen are analyzed using statistical correlation
analyses of daily data. The six measurement sites represent
different surfaces (hummocks, lawns, and hollows) of the mire.

The methane emissions increased with increasing peat
temperature. Due to the high autocorrelation properties of the
temperature time series, it was not possible to conclude
whether the temperature affected methane emissions with lag or
instantly.

Depth of the water table and methane emissions had
statistically significant, negative cross correlations for all
lags. The dumping effect of precipitation or the increased
diffusion rate caused by the declining water table could
explain the result. In addition, the actual dynamics between
water table fluctuations and methane emissions was probably
difficult to see due to the rather constant water table during
the measurement period. The results showed that the general
assumption that methane emissions increase with increasing
water table is not always true. The differentiated water table
series and methane emissions correlated positively for five of
the sites studied. Precipitation increased emissions with a
few days lag in one hummock, a lawn-low hummock and a lawn
site. The emissions from the other hummock and a hollow showed
two-peaked cross correlations with precipitation indicating
two mechanisms affecting the dynamics.

Generally, the responses of the methane fluxes to
precipitation and changes in water table indicated similar
time lags of the dynamics. The similar response naturally
reflects the effect of precipitation on the water table.
Methane flux from a hollow surface seemed to respond fast to
rain falls and changes in water table. The emissions from the
other hollow showed both a fast and a slow response. In the
lawn-low hummock, the lawn and one hummock site, methane flux
showed a slow response. However, cross correlation analyses
revealed different aspects of the dynamics.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

THE GLOBAL CARBON BUDGET AND ITS UNCERTAINTY
DERIVED FROM CARBON DIOXIDE AND CARBON ISOTOPE RECORDS

H. S. Kheshgi1, A. K. Jain2 and D. J. Wuebbles2

1Exxon Research and Engineering Company,
Route 22 East, Annandale, NJ 08801, USA

2University of Illinois, Department of Atmospheric Sciences,
Urbana, IL 61801, USA

The atmospheric record of CO2 concentration along with
estimates of CO2 emissions from the burning of fossil fuels
has been used to estimate the net uptake of carbon by the
oceans and the terrestrial biosphere. The split between carbon
uptake by the oceans and by the terrestrial biosphere has been
estimated using mechanistic models for the ocean uptake along
with carbon isotopic data which form constraints on the
contemporary global carbon budget. In this study we apply a
model for the global carbon cycle to reproduce CO2 and carbon
isotope records. We then consider the uncertainty of the
derived carbon budget based on estimates of uncertainty in the
records as well as uncertainty in model parameters.

A globally aggregated model of carbon cycle with an
upwelling/diffusion ocean and six-box biosphere is developed
to consistently reconstruct the carbon cycle and isotopic
variation in the atmosphere and oceans. The model-calculated
atmospheric d13C trend, based on a model that reproduces the
CO2 concentration record, agrees well with the observed ice
core and tree-ring d13C records. The model has also been used
to estimate the d13C of oceanic dissolved inorganic carbon and
our model results match observations well within the range of
observational uncertainty. This model is found to also match
measured values within measurement error of the pre-bomb
decrease in 14C in the atmosphere and the mixed layer due to
the Suess Effect, the bomb-14C in the mixed layer, the
bomb-14C penetration depth, the bomb-14C ocean inventory, and
the vertical distribution of total dissolved carbon and 14C.
Our confidence in both experimental techniques and our
understanding of global carbon cycle is strengthened by the
consistency between carbon isotope concentration data and
model results. With this model we make a quantitative
reconstruction of the past carbon budget. We consider the effect of the carbon isotopic constraints on
the uncertainty of the reconstruction of the past carbon
budget by Bayesian estimation of model parameters. We begin
with prior estimates of model parameters (such as
fractionation coefficients and land use emissions) along with
their uncertainties. Data-based quantities of CO2, 14C and 13C
(such as ocean inventory of bomb-14C) along with the
uncertainties of these quantities are used to make posterior
estimates of model parameters and their uncertainties. The
implications and limitations of this approach will be
discussed.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

THE GLOBAL CARBON BUDGET AND ITS UNCERTAINTY DERIVED FROM
CARBON DIOXIDE AND CARBON ISOTOPE RECORDS

H. S. Kheshgi1, A. K. Jain2 and D. J. Wuebbles2

1Exxon Research and Engineering Company,
Route 22 East, Annandale, NJ 08801, USA

2University of Illinois, Department of Atmospheric Sciences,
Urbana, IL 61801, USA
The atmospheric record of CO2 concentration along with
estimates of CO2 emissions from the burning of fossil fuels has
been used to estimate the net uptake of carbon by the oceans
and the terrestrial biosphere. The split between carbon uptake
by the oceans and by the terrestrial biosphere has been
estimated using mechanistic models for the ocean uptake along
with carbon isotopic data which form constraints on the
contemporary global carbon budget. In this study we apply a
model for the global carbon cycle to reproduce CO2 and carbon
isotope records. We then consider the uncertainty of the
derived carbon budget based on estimates of uncertainty in the
records as well as uncertainty in model parameters.

A globally aggregated model of carbon cycle with an
upwelling/diffusion ocean and six-box biosphere is developed
to consistently reconstruct the carbon cycle and isotopic
variation in the atmosphere and oceans. The model-calculated
atmospheric EB13C trend, based on a model that reproduces the
CO2 concentration record, agrees well with the observed ice
core and tree-ring EB13C records. The model has also been used
to estimate the EB13C of oceanic dissolved inorganic carbon and
our model results match observations well within the range of
observational uncertainty. This model is found to also match
measured values within measurement error of the pre-bomb
decrease in 14C in the atmosphere and the mixed layer due to
the Suess Effect, the bomb-14C in the mixed layer, the bomb-14C
penetration depth, the bomb-14C ocean inventory, and the
vertical distribution of total dissolved carbon and 14C. Our
confidence in both experimental techniques and our
understanding of global carbon cycle is strengthened by the
consistency between carbon isotope concentration data and
model results. With this model we make a quantitative
reconstruction of the past carbon budget.
We consider the effect of the carbon isotopic constraints on
the uncertainty of the reconstruction of the past carbon
budget by Bayesian estimation of model parameters. We begin
with prior estimates of model parameters (such as
fractionation coefficients and land use emissions) along with
their uncertainties. Data-based quantities of CO2, 14C and 13C
(such as ocean inventory of bomb-14C) along with the
uncertainties of these quantities are used to make posterior
estimates of model parameters and their uncertainties. The
implications and limitations of this approach will be
discussed.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

THE SIMULATION OF THE GLOBAL CLIMATE FLUCTUATIONS
DURING LITTLE ICE AGE

Alexander V. Kislov1 and Valeria V. Popova2
1Dept. Meteorology and Climatology, University of Moscow,
119899, Russia

2Lab. Climatology, Institute of Geography, Moscow, Russia

The empiric data of climate for last stage of Little Ice Age
(LIA) 1780-1820 yr including the sea surface trmperature (SST)
data were analysed. It was shown that there were no modifica-
tion in 'outer' forcing during this period. Employing a
simplified model of global circulation of atmosphere a
simulation of climate sensitivity to the changes of SST has
been carried out. There is a agreement between the
simulationly reproduced temperature anomalies over continents
and empiric data. This result show at least that there are
concordance between different empiric data. Our result show
that LIA is example of manifestation of selfoscillation in
climate system.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


THE ROLE OF LANDSCAPE FEEDBACK IN THE RESPONSE
OF CLIMATE TO ORBITAL FORCING

Alexander V. Kislov

Dept. Meteorology and Climatology
University of Moscow, 119899, Russia

The experiments were carried out using the simplified general
circulation model (SGCM) to investigate the climate
sensitivity to the changes of the insolation distribution at
the outer atmosphere boundary and the surface characteristics
during Last Pleistocene and Holocene. A paleoclimate change
scenario over Kaspian sea (Central Asia) generated using a
limited area model nested in a SGCM. It was shown that
Milancovitch effect was a key factor in climate dynamic. In
arid tropical and subtropical zones a minor factor was
landscape's feedback. Climate change determined modification
of the landscapes, they determined changes of albedo and
transpiration and there were climate variation of regional
scale.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


UFIS -- INFORMATION ON ECOLOGICAL RESEARCH

M. Knorrenschild, R. Lenz, S. Gayler, A. Kaune, W. Sinowski

GSF -- Research Center for Environment and Health, PUC
P. O. Box 1129, 85758 Oberschleissheim, Germany

UFIS is an online information system on ecological research,
in particular information on models and data relevant to
models. While the latter part of the project is still in the
conceptual phase online information on models is already
available in the first stage. The model information consists
of a completed model questionnaire containing descriptions of
the situation modelled, theoretical background, processes
modelled, variables involved, input data required and
technical requirements.

UFIS is made possible through a grant of the German Federal
Ministry of information on models is already available in the
first stage. The model information consists of a completed
model questionnaire containing descriptions of the situation
modelled, theoretical background, processes modelled,
variables involved, input data required and technical
requirements. UFIS is made possible through a grant of the
German Federal Ministry of Education, Science, Research and
Technology (BMBF). UFIS goal is to assist ecological
researchers in maintaining awareness of the state of the art
in modelling and also to provide funding agencies and
scientific management boards with an overview of current
activities.
Due to its broad scope UFIS presents a potentially valuable
tool for research in issues of global change. UFIS' design
with respect to model data will be coordinated with already
existing databases on national and international level in
order to ensure compatibility. The information in UFIS is
accessible via the WWW, classification of this information in
various respects is available in order to assist the user to
find the details on a model that is of interest. Currently
there are 12 models documented to full detail in the UFIS
database. The poster will highlight the model information
available, illustrate the WWW interface to the UFIS database
and its use, and show examples of retrievals.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


THE INFLUENCE OF CLIMATE CHANGE ON THE NITROGEN BUDGET
OF FOREST SOILS

Kolb, E., K. E. Rehfuess

Lehrstuhl f1r Bodenkunde und Standortslehre, Luwig-
Maximilians-Universit4t,
HohenbachernstraE1e 22, D-85354 Freising, Germany

Climate change would have fundamental consequences on
structure, function and stability of forest ecosystems. The
soils and their bioelement budgets, especially the N-budget,
have a key function in steering and controlling these
ecosystems.
The following questions arise:
1. Will the release of nitrogen production increase after
global warming, provided soil humidity stays the same?
2. Will the nitrogen loss in a warmer climate be stronger in
biologically inactive humus forms than in active ones?
3. What will be the effect of temperature on the net-
mineralization of nitrogen in different seasons?
In the Bavarian Alps (Mangfall-Alps, Tegernsee) 90 undisturbed
soil cores were excavated and re-buried. One third of them
were reburied in the original altitude of 1250 m NN. The
others were translocated to sites with altitudes of 1010 and
740 m NN respectively, equivalent to a raise in temperature of
about 1F8C and 2F8C. We investigated a Loose Brown Earth with
raw humus (the inactive humus form, in the following
abbreviated as RH ) and a Loose Brown Earth with moder (the
active humus form, in the following abbreviated as MO ). To
examine the effect of disturbance in the upperslope position,
we also investigated 10 soil units of the RH, which had not
been taken as cores, but remained undisturbed and untrenched.
To study nitrogen release, soil water from the cores was
sampled every 2 to 4 weeks from the subsoil in 30 cm depth
with suction cups. It was analysed for all important
bioelements, including aluminium, pH and conductivity. The
predominant nitrogen compound in the investigated soil water
was nitrate.
A comparison of both soil types yields the following results:
1. Both variants that were translocated to warmer sites
differ significantly from the control (upperslope
position); the reaction of MO is stronger than that of
RH.
2. MO reacts clearly at temperature differences of as little
as 1F8C.
3. The warmer climate has an effect on MO both in winter and
summer, while RH reacts in summer periods only.
4. In winter 1993/94 (1F8C warmer than 1992/93) the nitrogen
net-mineralization was accelerated for both soil types as
compared to the winter 1992/93.
5. Beyond a certain temperature threshold, RH reacts very
intensively for a short time with high nitrogen outputs.
The questions raised at the outset of the project can thus be
answered as follows:
1. In the experiment both soil types exhibit higher nitrogen
mineralization in warmer climate.
2. Contrary to the current knowledge, the active soil type
Loose Brown Earth with moder reacts more strongly than
the Loose Brown Earth with raw humus.
3. In both soil types, nitrogen release is accelerated in
summer, and RH is during the vegetation period more
reactive than MO; however the latter releases more N in
winter resulting in a higher total N mineralization.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

RUNOFF, TOTAL ORGANIC CARBON AND TOTAL NITROGEN LEACHING
FROM FORESTED CATCHMENTS IN FINLAND SINCE THE 1960's

P. Kortelainen1 and S. Saukkonen2
1Finnish Environment Agency, P.O. Box 140,00251 Helsinki, Finland
2Central Finland Regional Environment Centre,P.O. Box 110, 40101 Jyvdskyld, Finland
The cold climate and flat topography in Finland provide
favourable conditions for organic matter accumulation. One
third of the land area in Finland was originally covered by
peatlands, half of which has been ditched for forestry. 87 %
of the total land area is presently classified as forestry
land. This study provides an assessment of the annual leaching
of organic carbon and nitrogen from typical Finnish forested
catchments since the 1960's.
The 22 study catchments (0.69-56 km2) are located over Finland
excluding the northernmost regions. Forestry and atmospheric
deposition can be considered the only significant human
impacts; less than 6 % of the catchments is covered by
agricultural fields. The forestry practices (ditching,
clear-cutting, scarification and fertilization) in the
catchments during the last 30 years have been figured out. The
proportion of the catchments covered by peatlands ranges from
10 to 87 % and the ditching intensity from 0 to 100 %. The
catchments are natural hydrological units, and runoff and
stream water quality have been monitored since 1962-1976 under
variable hydrological conditions. Daily runoff was recorded in
14 catchments; in the remaining 8 catchments leaching
calculations were based on runoff data from the catchments
nearby.
The mean annual runoff from the study catchments, 230 to 430
mm a-1, agree with the mean annual runoff in Finland, 301 mm
a-1, during 1931-1990 (Kuusisto 1992). The runoff from the
catchments increased to the north (r23D0.62). This trend
compensated for the lowest total organic carbon (TOC) and
total nitrogen (Ntot) concentrations recorded for the
northernmost catchments such that there was little variation
in the mean annual leaching between the catchments. The
regional variation in the mean annual leaching of TOC and Ntot
was smaller (2 600-8 800 kg km-2 a-1 and 100-290 kg km-2 a-1,
respectively) than the interannual variation in the
catchments. The leaching was lowest in the northernmost
catchments with low peatland proportion.
The longterm monitoring and the regional representativeness of
the catchments give an overview of the leaching of TOC and Ntot
from typical Finnish forestry land. Hydrological conditions
dominated the leaching pattern causing large variations in
annual leaching in each catchment. The decennial average
runoff and leaching values were, however, rather close to each
other. The 1970's was the driest decade in most catchments
with average runoff of about 300 mm a-1. The runoff was highest
in the early 1990's (350 mm a-1). The leaching of TOC and Ntot
were predominantly lowest in the 1970's. The average Ntot
leaching was almost the same (200 kg km-2 a-1) both in the
1960's, 1980's and in the early 1990's. About half of the
annual runoff and leaching was concentrated to spring periods,
although the lenght of the spring period represented only
10-15 % of the whole year. The impact of climate change on the
annual runoff and leaching will be discussed. Moreover, the
impact of mild winters on the spring leaching will be
considered.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

SITUATION AND NEED OF CRITICAL LOADS ASSESSMENT IN THAILAND

M.Kozlov and S.Towprayoon

Division of Environmental Technology, School of Energy and
Materials,
King Mongkut's Institute of Technology Thonburi,
Rataburana Bangkok 10140 THAILAND

The purpose of this study is to estimate the needs of
assessment of acid deposition for Thailand conditions.
Antropogenic emissions of acid rain precursors occur during
the combustion of fossil fuels,especially coal, for energy
production. T ese emissions for Thailand are currently at high
level and in the year 2001 it is found that for the base case
scenario with no emission controls the total sulphur dioxide
emission is approximated at 3.55 Mt.
Some of the ecosystems of the Asia region are similar to those
found in areas of Europe, but many other ones are very
different and research have to be conducted to analyze and
assess the relative sensitivity of these various anthropogenic
and natur l environments to acidic inputs. The sensitivity of
Thailand ecosystems should be described by means of
preliminary Critical Loads (CL) a new concept has been agreed
both nationally and internationally in order to improve the
situation with lon range transboundary air pollution.

Taking into account the specification and diversity of
ecosystems on the area of investigations and low degree of
information support for calculation of various parameters we
should use methodology of quantitative assessment of the
critical lo ds. This methodology use combinations of expert
approaches and geoinformation systems including different
modern methods of expert modelling .These systems can operate
using data bases relative to the areas with great spatial data
uncertainty. As a rule, the given systems include an analysis
of the cycles of various elements in the key plots, a choice
of algorithm describing these cycles and corresponding
interpretation of the data. This approach requires numerous
cartographic m terials, for example, maps of soil cover,
geochemical and biogeochemical structure, self-purification
capacity of soil, water, atmosphere, etc. It is the most
applicable approach for asian countries because there is no
way of presentin an adequate information for the great spatial
variability of natural and anthropogenic factors.

Taken into account these approaches as well as the necessity
of using the unique european approaches for quantitative
assessment and mapping of critical loads, this research give
for us the first approximation for CL values.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

INFORMATION AND MATHEMATICAL ASPECTS OF PREDICTABILITY
PROBLEMS OF GLOBAL CHANGE

V. Kozoderov

Institute of Computational Mathematics, Russian Academy of
Sciences,
Moscow 117334, Leninsky Prospect 32A, RUSSIA


The Comtemporary Era of the GAIM project development is
characterized by sets of Multisprectral Satellite (MSS) data
compiled for the period near to 20 years, and large volumes of
similar data are planned by the Earth Observing Systems (EOS).
Thus, it is worthwhile to think about applications of the
relevant geoinformation models, i.e. constructed from the
data, for prognostic purposes. To solve the problems, unified
mathematical procedures are evolved, which require an urgent
necessity to define stringent information metrics for MSS
imagery as well as to develop retrieval techniques for state
parameters /the amount of biomass for continental biophere, in
particular). The predictability is then defined as a
signal/noise ratio in cross-correlations of the anomalies for
the bioproductivity parameters between "particular points
(areas, zones)" of the soil-vegetation system and surrounding
terrains on the MSS images. Since spectral signatures and
structural composition of the corresponding MSS classes are
dependent on sun illumination con- ditions and viewing
geometry for scenes under processing, new procedures are
presented to retrieve the invariant parameters based on
samples of ground measurements in special field campaigns and
on extrapolation methods for applying the learning samples to
individual pixels of related classes. The information andthermodynamic dualism of the entropy functional would enable
to merge the information metrics (entropy, redundance,
conditional entropy, etc.) and the state parameter assessments
for MSS imagery. It is shown that calculating the entropy
metrics one can find specific contextually coherent structures
on the images in the spatial complexity domain instead oftraditionally abundant classes given by routine pattern recog-

nition and scene analysis techniques. As a result, each pixel
of the MSS imagery is represented in the form of the
parameters, i.e. the images would be normalized by the entropy
metrics. This gives a unique tool to elaborate the
predictability models using the above cross-correlations for
the indicated anomalies on the scales of interannual
variability in the invariant products with the internal
harmonics being filtered out in temporal sets of the product.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

BIOGEOCHEMICAL DATA AND APPROACH TO MODEL OF INTERACTION BETWEEN ENVIRONMENT AND MARINE ORGANISMS

E. Krasnov

Altlantic branch of Institute of Oceanology, Russian Academy of Science , pr. Mira 1, 236000 Kaliningrad, Russia

Variations of some biogeochemical parameters (18O, 13C, Ca/Mg, Ca/Sr) of successive layers of carbonate shell growth of several recent and well preserved fossil molluscs from Atlantic and Pacific areas will be observed in accordance to global change of environmental temperature.

Seasonal changes in values of oxygen isotopes, Ca/Mg, Ca/Sr ratios for biocarbonates from successive layers of recent bivalve shells are synchronized with seasonal periodicity of sea water temperature. Ridges of the shells of Swiftopecten swifti inhabiting the upper part of sublittoral zone of the Sea of Japan and those of the fossils Swiftopecten swifti from the Pliocene of Aomori area (Northern Honsu of Japan) are formed at comparatively high summer temperatures equal to +12- 16=F8C. The beginning of the growth of the fire wide band of the shells occurring at maximal temperatures of +25=F8C. The isotope thermometry did not register temperatures below +2-4=F8C in studied specimens.

In the Pliocene shells of Cyprina islandica from Island and Swiftopecten swifti from Japan minimal growth temperature were registered by biogeochemical markers to be not less than +3- 6=F8C. In Mizuchopectin yessoensis according to the Ca/Mg data the most high summer temperatures of growth was +21.7=F8C and the minimal winter one was +1-3=F8C.

Thus, biogeochemical data from successive layers of sea mollusc shells can be regarded as registrating structures which record either seasonal or any other changes of environmental temperature with regard to various parameters for global modelling. But real difficulties connected with diagenetic changes of mineral composition of shells, specificity of growth rate of different species and others also will be observed.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


THE ROLE OF SNOW COVER IN THE CLIMATE CHANGES
ACCORDING TO THE EXPERIMENTS
WITH THE SIMPLIFIED GLOBAL CIRCULATION MODEL

A. N. Krenke1, E. V. Prigarin2 and D. V. Turkov1

1Institute of Geography, Russian Academy of Sciences,
Staromonetny 29, Moscow, 109017, RUSSIA.

2Computing Center of the Russian Academy of Sciences,
Vavilova, 40, Moscow, 117333, Russia.

According to the heat balance assessments the snow cover cools
the contemporary Earth's troposphere no less than by 2 deg. C
due to the additional radiative cooling and the heat sink on
melting, compensated by the turbulent influx from the air.
Contemporary interdecade and interannual variations of the
global snow-ice cover are in the order of 0,3 deg.C, which
coincides with the observed interdecade and interannual
variability.
To reveal the features of snow cover impact on climate we
have accomplished the experiments with the simplified Global
Circulation Model. This model has 10*12 cells, three levels
for air motion and five for radiation fluxes, clouds and
prcipitation. The contamporary climate is well reproduced by
the model with diffusion terms instead of missing sinoptic
scale transfere. The experiments were fullfilled with and
without diffusion tj increase the model sensibility to the
underlying surface.
The experiments included, firstly, the variations of snow
cover surface in the model with the stationary regime for the
January and the July and, secondly, the changes in the melt
water input in the soils in the spring ( that is the snow
water equivalent) in the model with the seasonal evolution.
The displacement of snow cover in January from 48 deg.N to the
36 deg, n leads to the small cooling above the new snow and to
significant ( up to 5 deg.C) warming in the more high
latitudes above the old snow duue to increasing meridional and
zonal ( from the ocean) circulation. The displacement of snow
in higher latitudes leads only to the cooling of the air. The
displacement of snow in July from the 72 deg. n to the 48
deg.N (The Ice age conditions) also provoced the increase of
the heat advection and the cooling due the heat sink in the
snow is evidently insufficient to save the snow from melting.
Therefore the evolution of polar glaciation into the "White
Earth" seems impossible. On the other hand due to negative
feedback through the air circulation the stable climate forms
in case of perennial snow-ice cover in size of quaternary
glaciation. The same area of glaciation is reconstructed now
for the early proterozoic, vend, sillur and carbon (Gondvana
Glaciation).
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


GLOBAL ANALYSIS OF NIMBUS-7 SNOW MASS,
NORTHERN HEMISPHERE TEMPERATURE ANOMALIES,
SEA LEVEL PRESSURE AND THEIR ASSOCIATION WITH
INDIAN SUMMER MONSOON RAINFALL

R. H. Kripalani

Indian Institute of Tropical Meteorology, Pune-411008, India

In this study empirical relationships between Nimbus-7 snow
mass, Northern Hemisphere (NH) Temperature Anomalies and Sea
Level Pressure (SLP) with Indian Summer Monsoon Rainfall
(ISMR) are investigated. The basic purpose is to find whether
there are specific regions over the NH over which the snow
mass/temperature anomalies/SLP influence the interannual and
intraseasonal variability of the ISMR.

The scanning Multi-channel microwave radiometer (SMMR) on the
Nimbus-7 satellite was acquiring passive microwave data which
was used to measure snow depth on an areal basis. The snow
depth data (1979-1987) was acquired from the National Space
Science Data Center, Goddard Space Flight Center, Maryland,
USA. The data for the NH Temperature Anomalies (1854-1993) SLP
(1899-1993) was prepared by the Data Support Section, National
Center for Atmospheric Research, Boulder, Colorado, USA.

Preliminary global data analysis reveals that the January snow
mass over two regions of former USSR - one located north-east
of Moscow and the other lying between Mongolia and Siberia -
shows high inverse relationship with subsequent ISMR. Even the
NH temperature anomalies reveal that positive (negative)
temperature anomalies as high (low) as 5F8C (- 4F8C) are
observed for the month of January over the NH bounded roughly
between 50F8-70F8 N, 20F8-90F8 E for excess (deficient) ISMR. The
January (May) SLP over 65F8N 30F8 E (20F8 N 60F8 E) shows signifi-

cant correlation with ISMR. Implications of these results in
extended range forecasting of the Indian summer monsoon (June-
September) rainfall are explored.

Part of the above work was done at the Florida State
University, Tallahassee, USA during the visit of the author
during the period February-May 1994.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


A FINITE ELEMENT ABL MODEL FOR A COASTAL STATION

PK Kunhikrishnan and S Muraleedharan Nair

Space Physics Laboratory
Vikram Sarabhai Space Centre
Trivandrum 695 022


The characteristic feature of atmospheric boundary layer in a
coastal area is its modification by seabreeze circulation and
formation of thermal internal boundary layer (TIBL). The
atmospheric boundary layer (ABL) observational studies
conducted at Thumba (8.5F8N, 76.9F8E) using sodar, tower based
instruments radiosonde an tethersonde show that the observed
TIBL depth at Thumba is always higher than that derived from
the empirical relations available in literature. This suggests
that the empirical relations available in the literature may
not be applicable as such to this low latitude coastal
station.

Inorder to simulate ABL features during sea breeze activity a
two dimensional multilevel ABL model is developed. The
governing equations considered in this model are the three
equations for the conservation of momentum, one equation for
conservation of mass and a thermodynamic energy equation. A
first order closure scheme is employed for the turbulence
parameterization of heat and momentum. The present model uses
a profile scheme proposed by O'Brien (1970) for exchange
coefficient. The numerical scheme used for solving the
governing equations is the finite element method. A weighted
residual approach is used for solving the differential equa-

tions.

Based on the above scheme a code is developed and the
performance of the code is tested by the numerical
experiments.

1. Generation of classical Ekman Spiral.

2. Simulation of wind profile for a 1-D steady state
ABL under neutral stability using O'Briens
turbulence scheme of exchange coefficients.

3. Vertical wind generation due to pure differential
roughness change.

The test results are encouraging.


Reference

O'Brien, J.J., 1970, `A note on the vertical structure of the
eddy exchange coefficient in the planetary boundary layer', J.
Atmos. Sci., 27, 1213-1215.

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CLIMATE SENSITIVITY EXPERIMENTS FOR THE CHANGED ORBITAL
CONDITIONS AND CHANGED BOREAL FOREST AND SUBTROPICAL
GRASSLAND DISTRIBUTIONS OF 6000 YR BP

J.E. Kutzbach, J.A. Foley, and R.G. Gallimore

Center for Climatic Research, University of Wisconsin-Madison
1225 West Dayton Street, Madison, WI 53706, USA

Using orbital conditions for 6000 yr BP, climate models
simulate an enhanced seasonal cycle in the northern
hemisphere, with a stronger African/Asian summer monsoon. In
the high northern latitudes, increased insolation leads to
higher ocean temperatures and delays the formation of sea ice,
resulting in warmer winter conditions and hence year-round
warming. The changes in precipitation and temperature are
large enough to influence the distribution of vegetation.
Field evidence from the mid-Holocene indicates that the boreal
forest expanded northward in North America and Eurasia,
replacing tundra, and subtropical grasslands expanded
northward in North Africa, replacing desert. Experiments with
climate models show that a northward expansion of the boreal
forest could have produced additional high- latitude warming
(Foley et al., 1994) and thus a positive feedback. Similarly,
vegetation sensitivity experiments indicate that northward
expansion of grasslands in North Africa could have enhanced
monsoon precipitation, although this positive feedback may not
be as strong as the boreal forest feedback.
Climate models for 6000 yr BP also simulate drier conditions
in northern continental interiors and seasonal cycles of
reduced amplitude in the southern hemisphere; it will be of
interest to test for regional vegetation feedbacks in these
areas too.
The changes in high-latitude insolation and vegetation were
larger during the last interglacial than during the Holocene
(Harrison et al., 1995). During periods of cool summer orbits,
such as around 115,000 yr BP, model simulations suggest that
the southward expansion of tundra, replacing boreal forest,
could have helped to promote the initiation of year-round
snowcover.
Biosphere/atmosphere interactions in climate models are
influenced by the choice of model parameterizations and in
particular by the form of atmosphere/ocean coupling.

References

Harrison, S.P., J.E. Kutzbach, I.C. Prentice, P.J. Behling,
and M.T. Sykes (1995). The response of Northern Hemisphere
extratropical climate and vegetation to orbitally induced
changes in insolation during the last interglaciation.
Quaternary Research 43, 174-184.
Foley, J.A. and J.E. Kutzbach (1994). Feedbacks between
climate and boreal forests during the Holocene epoch. Nature
371, 52-54.


>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

POTENTIAL IMPACT OF CLIMATE CHANGE ON TRACE GAS EMISSIONS
AND SOIL NITROGEN CYCLING
IN SOUTHWESTERN U.S. FOREST ECOSYSTEMS

K. Laun, Fachbereich VI, Physische Geographie, Universit4t
Trier,
54286 Trier, Germany, laun@alpine.for.nau.edu

S.C. Hart, School of Forestry, Northern Arizona University,
Flagstaff, AZ, sch@alpine.for.nau.edu

Global warming potentially leads to an increase in microbial
activity resulting in enhanced trace gas emissions of nitrous
oxide and carbon dioxide, and increased uptake of methane in
upland soils. An inexpensive and potentially powerful way to
investigate the effects of climate change on soils is to
transfer intact soil cores along natural temperature gradients
from higher to lower elevations. We used this approach to
study the potential impacts of global warming on trace gas
fluxes and soil nitrogen cycling at two sites along the slopes
of the San Francisco Mountains near Flagstaff, Arizona. A
total of eight intact soil cores were taken from an elevation
of 3100 m and incubated at an elevation of 2100 m, where the
mean annual air temperature is approximately 3-4F8 C higher.
Additionally, eight intact soil cores were incubated in situ
and eight soil covers were used to measure ambient trace gas
fluxes. The comparison of the in situ soil cores with the soil
covers allows the assessment of root exclusion on trace gas
fluxes. Static, vented chambers were used to measure carbon
dioxide, methane and nitrous oxide fluxes biweekly to monthly
during the snow-free season. Annual net rates of nitrogen
mineralization and nitrification were determined for
transferred and in situ soil cores using the ion exchange
resin-soil core method. Based on the assumption that climate
change can be adequately simulated by transplanting soil cores
from higher to lower elevation, these data are an important
contribution to the quantification of changes in trace gas
fluxes and soil nitrogen cycling rates that may occur as a
result of global warming. Inexpensive, and hence replicatable,
approaches for studying the potential effects of climate
change on soil processes will enhance our understanding of the
potential feedbacks between the lithosphere and the
atmosphere, and be valuable to investigators modelling the
response of the biosphere to global warming.

It has been recognized early with the climate models that the land-processes
play an important role in the state of the atmosphere.
The first effect, often mentioned, is the influence of albedo variation
on the precipitation rate, as defined by Charney mechanism. But one must
distinguish between the desertification of a semi-arid zone as discussed
first by Charney and the effect of the deforestation of an equatorial
forest.
The role of drag coefficient must also be emphasized. This coefficient,
which plays a role in the convergence of mass and moisture in a large
area is affected by a deforestation.The effect on the circulation may be
important.
The evapotranspiration rate is also dependent on the vegetation type
through the soil moisture content and surface resistance of the cover.
The temporal evolution of the latent heat flux and moisture budget are
consequently affected by a vegetation change.
All these effects will be discussed and the conclusions reinforced by
numerical experiments conducted with GCMs.


>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

THE EFFECT ON CLIMATE OF DEFORESTATION AND DESERTIFICATION

K. LAVAL
LMD. 24 RUE LHOMOND. PARIS

It has been recognized early with the climate models that the land-processes play an important role in the state of the atmosphere. The first effect, often mentioned, is the influence of albedo variation on the precipitation rate, as defined by Charney mechanism. But one must distinguish between the desertification of a semi-arid zone as discussed first by Charney and the effect of the deforestation of an equatorial forest.

The role of drag coefficient must also be emphasized. This coefficient, which plays a role in the convergence of mass and moisture in a large area is affected by a deforestation.The effect on the circulation may be important.

The evapotranspiration rate is also dependent on the vegetation type through the soil moisture content and surface resistance of the cover. The temporal evolution of the latent heat flux and moisture budget are consequently affected by a vegetation change. All these effects will be discussed and the conclusions reinforced by numerical experiments conducted with GCMs.

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A COMPARISON OF MODELLED CO2 DISTRIBUTIONS
ARISING FROM PRESCRIBED SOURCES

R.M. Law,P.J. Rayner and I.G.Enting

CRC for Southern Hemisphere Meteorology, 8 Redwood Dr.
Notting Hill,3168, Australia,
email: rml@vortex.shm.monash.edu.au, pjr@dar.csiro.au,
ige@dar.csiro.au


The spatial structure of CO2 can provide a good deal of
information about the spatial structure of sources and sinks
of this important trace gas. In order to relate net sources to
the observed distribution we require some knowledge of the
redistribution by atmospheric transport. Three-dimensional
atmospherictracer transport models provide the best tool
available for this purpose.

Such models have been used in a number of studies inferring
net carbon sources from CO2 observing networks and have
produced a wide variety of results.It has been difficult to
assess how much of this variety stems from differences in
methodology, observations used or simulated atmospheric
transport.

To quantify the last point we have coordinated a study in
which the same set of CO2 sources have been input to a range of
tracer transport models. The models used include both on and
off line models, those using analyzed and GCM-generated winds
and a range of advection schemes and subgrid-scale
parameterizations. The models hitherto used in CO2 inversion
studies are covered in the comparison.

The poster presents a summary of some of this work.

The two sources we used were the input of fossil carbon and an
estimate of the seasonal terrestrial exchange. In both cases
there is a large spread of simulated responses. The annual
mean zonal mean interhemispheric gradient at the surface
arising from fossil fuel input varies by a factor 2.The
peak-to-peak amplitude (a rough measure of seasonality) of the
response to the terrestrial exchange varies similarly with
even larger variations over large northern land masses. Away
from the surface the results show qualitative as well as
quantitative differences, as shown by the annual mean zonal
mean response to fossil fuel input at 200hPa.

Finally we show that the current observing network, based on
remote oceanic sites, underestimates the variation from model
to model in the above experiments. This suggests that, as new
stations nearer these sources are included the improved
resolution in inversions will be offset by increased model
uncertainty.

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IMAGE 2.1: AN INTEGRATIVE MODEL FOR THE EARTH SYSTEM

Rik Leemans and Joe Alcamo

Department of Terrestrial Ecology and Global Change,
National Institute of Public Health and Environmental
Protection,
RIVM, P.O. Box 1, 3720 BA Bilthoven, The Netherlands

We present the IMAGE 2.1 model which is designed to simulated
global greenhouse gas emissions and atmospheric concentrations
for the period 1970-2100. The model is primarily aimed to
develop and evaluate climate policies, but for reliability and
robustness of such integrated model, it should be based on
state-of-the-art scientific understanding of the Earth systems
(including the anthroposphere). The model therefore consists
of 3 major subsystems: the Energy/Industry emissions models,
the terrestrial biosphere models and the atmosphere/ ocean
models. IMAGE 2.1 simulates the emissions of GHGs from the
different sectors and includes feedbacks such as the influence
of climatic change and changing atmospheric CO2 concentrations
on plant and crop growth, and their distributions, as well on
energy-use. External input to the different models consist of
demographical, technological and socio-economical development.
The terrestrial biosphere model leads to dynamic simulations
of land use and land cover patterns through time and their
influence on the global C cycle and CO2 fluxes and emissions of
other GHGs. Feedbacks included are a regionalized
CO2-fertilization effect, changes in water use efficiency,
changes in plant growth and soil respiration, and vegetation
and crop redistribution. Socio-economically driven changes in
land use generate new patterns of land cover with regionally
expanding or contracting of arable lands.
The capabilities of determining the effect of different
scenarios will be illustrated with simulations of a plausible
baseline scenario, and several other scenarios highlighting
different policy options. All scenarios depend on the middle
UN populations and economical development figures.
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OBJECTIVE MAPPING OF THE SEASONAL VARIABILITYOF
THE OCEAN-ATMOSPHERE PCO2 DIFFERENCE IN
THE NORTH ATLANTIC OCEAN

N. LefAvre1,2,3

1LODYC, Universit Pierre et Marie Curie,
4 place Jussieu, 75252 Paris Cedex 05, France

2IGBP-DIS, Universit Pierre et Marie Curie

3LMCE, CEA, Saclay, Orme des merisiers,
91191 Gif-sur-Yvette, France

Measurements of partial pressure of carbon dioxide (PCO2) in
the oceans are needed to validate models of the carbon cycle.
Although the ocean acts as a major sink for anthropogenic CO2,
quantifying just how much is absorbed remains difficult. Even
the CO2 sink in the North Atlantic, the most studied ocean in
the world, remains a subject of controversy.

Maps of PCO2, the difference between oceanic and atmospheric
PCO2, have been produced for the North Atlantic (10F8S to 80F8N),
from existing PCO2 measurements collected over 15 years (1978
- 1993). More than 29000 measurements were averaged on a 1 by
1 degree grid and then processed with an objective analysis
technique. Because this study employs such a technique, the
seasonal maps of PCO2 are accompanied by seasonal maps of
associated errors. Data gaps are present and vary with season.
Furthermore, interannual variability was neglected.

The North Atlantic ocean is divided in three basins: the
equatorial band (10F8S-10F8N), the central Atlantic (30F8N-50F8N)
and the subarctic Atlantic (50F8N-80F8N). The equatorial band is
a source of CO2 in the atmosphere whereas other regions are
sinks. The central Atlantic does not exhibit strong seasonal
variability as the mean PCO2 is nearly the same all year
round. The subarctic Atlantic is a strong sink in summer (mean
PCO2 3D -60.6 +/- 7.7 atm) due to a strong biological
activity.

Results obtained with this objective analysis are compared
with previous studies in the North Atlantic ocean. Mean PCO2
values derived in this study over several regions where pub-

lished cruise data existed are in good agreement with each
other. A comparison with the recent interpolation approach of
Takahashi and coworkers, using a similar data set, is also
presented.

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#305

CHEMISTRY CHANGES IN THE TROPOSPHERE SINCE PRE-INDUSTRIAL TIMES

Jos Lelieveld

Air Quality Department, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands

During this century global average volume mixing ratios of methane (CH4) have increased from about 800 to 1700 ppbv and of carbon monoxide (CO) from about 50 to 100-200 ppbv. Because these gases are primarily removed from the atmosphere by their reaction with hydroxyl radicals (OH), these increases have reduced the OH abundance and thus the atmosphere's oxidation efficiency. On the other hand, growing levels of these gases can enhance photochemical formation of ozone (O3) in the troposphere. Moreover, extensive anthropogenic emissions of the O3 precursors CO, hydrocarbons and nitrogen oxides (NOx=3DNO+NO2), particularly in the industrialized northern hemisphere, have caused large scale photochemical O3 contamination of the troposphere, Since O3 and CH4 are effective absorbers of infrared radiation, their coupled increases exert significant upon climate.

According to recent source inventories, about 500-600 Tg/yr CH4, 1500-2000 Tg CO/yr and 40-50 Tg/yr NOx (as N) are currently emitted into the atmosphere. anthropogenic sources, for example, from energy use, biomass burning, and agricultural releases constitute major parts of these emissions. This paper presents results from a global three- dimensional model study, adopting first a contemporary trace gas emission scenario. After establishing reasonable confidence in the model performance by comparing its output with available measurements, the anthropogenic emission sources have been reduced according to population and industrial developments during the past 150 years. The results are compared to CH4 concentration estimates for the middle of the 19th century obtained from industrial changes in the chemistry of the troposphere.

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CHARACTERIZING THE ESSENTIAL SCALES OF ABIOTIC PROCESSES
AND SCALE INTERACTIONS AMONG ECOSYSTEMS IN THE
BORNHOVED LAKES AREA, NORTHERN GERMANY

Bai-Lian Li1, Felix M1ller2, Winfrid Kluge2,
Georg Hrmann2, and Wilhelm Windhorst2

1Center for Biosystems Modelling, Department of Industrial
Engineering,
Texas A&M University, College Station, TX 77854-3131, USA

2Ecosystem Research Center, University of Kiel,
Schauenburger Str. 112, D-24118 Kiel, Germany

Ecological systems as a major component of global change
operate over broad spatiotemporal scales. Hierarchy theory
conceptualizes such systems as composed of relatively isolated
levels, each operating at a distinct time and space scale.
Scaled structures have been noted in marine, freshwater, and
terrestrial ecosystems as well as global system. Ecologists
have recognized the importance of hierarchy theory in
ecological studies from local to global levels. But while the
theory is intuitively appealing as a way of looking at the
real ecological systems, ecologists have been frustrated by
the lack of appropriate quantitative methods to identify and
characterize such complex systems, especially when field
observation and experimental data are available. When we
approach these ecosystems with a particular scientific
question in mind, we normally only focus on a specific
spatiotemporal scale of observation. However, understanding
the function and their interaction of the above and below
scales of the ecosystem and its associated physical climate
and hydrologic systems is also important for modeling this
process, although most current ecosystem models do not account
for the hierarchical constraints that operate in the
ecosystem.
Wavelet analysis is a new mathematical theory and
computational method. Because of its characteristics of
time/space-frequency localization and multiresolution, the
wavelet transform of a signal can provide detailed information
of underlying ecological processes in time and/or spatial
scale. It provides a new way of looking at signals at various
scales. In wavelet representation, a signal is decomposed into
a sum of elementary building blocks describing its local
frequency content. This is exactly what is most desirable in
further investigation of detailed structures of ecological
signal energy components within subbands or subspectra and
their relationships among different rated processes of the
hierarchical ecosystem. In this paper, we use wavelet analysis
as an innovative hierarchical data analysis technique for
investigating multiscale spatiotemporal relationships among
ecological and physical processes at various ecological levels
of organization. There is a need in global data analysis,
interpretation, and modeling for methodologies for
representing, identifying, characterizing, and analyzing
multiscale spatiotemporal ecosystem dynamics.
The project of "Ecosystem Research in the Bornhoved Lakes Area
(Northern Germany)" is defined in a hierarchical framework.
Ecosystems in this area as processors of energy and matter are
extended over a wide range of spatiotemporal scales. We use
wavelet transforms and wavelet variance to characterize
changing scales of sampling data of air and soil temperatures
at different elevations, evaporation, heat flow, and wind
speeds at different elevations in the research area. We also
develop a wavelet-based multiscale correlation method to
explore the scale interactions of fluxes of water and
nutrients from the surrounding upland ecosystems into Lake
Belau ecosystem. Preliminary results have demonstrated that
these methods we used and developed is suitable to address our
scaling problem in data analysis, interpretation and modeling
of global environmental change. These new scaling information
may shed new light on looking at the long-term dynamics of the
coupling between the terrestrial ecosystem, the hydrological
cycle, and the physical climatic system, and provide potential
to give a detailed extrapolation across temporal or spatial
scales.

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Modeling carbonaceous aerosols

C. Liousse (a), J.E. Penner (b), C. Chuang (b), J.J. Walton (b), C.R. Molenkamp (b), H. Eddleman (b), and H. Cachier (a),

(a)Centre des Faibles Radioactivitis, CNRS-CEA, ave de la terrasse, 91198 Gif sur Yvette, France

(b)Global Climate Research Division, Lawrence Livermore National Laboratory, PO Box 808, L-262, Livermore, CA, 94551 USA

We have developed detailed emission inventories, based on the most recent experimental data for the amount of carbonaceous particles from biomass burning including wood fuel and charcoal burning, charcoal production, agricultural burning, savannah burning, and deforestation. Fossil fuel sources (diesel and coal) and natural sources were also taken in consideration. In this work, we focused on both black carbon and organic carbon emissions. These emissions are used together with our global aerosol model to study the global distribution of carbonaceous aerosols. The accuracy of the inventories and the model formulation is tested by comparing the model's simulations of carbonaceous particles with observations. The sensitivity of predicted concentrations is tested by varying the aerosol removal rates by deposition and the particle height injection. Also, aerosol optical depths and single scattering albedos are calculated from the simulated particle distribution including black and organic carbon, sulfates and dust particles. These values are shown to be in agreement with previous observations. Finally, from single scattering and surface albedos, a simple model shows a net cooling by atmospheric aerosols. Such results will be compared with global maps of climate forcing obtained by coupling our aerosol model with the Hamburg Climate Model (ECHAM3), as well as the NCAR Community Climate Model (CCM1).

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


MODELLING THE CONSUMPTION OF ATMOSPHERIC CO2 BYCONTINENTAL EROSION

W. Ludwig1, P. Amiotte-Suchet1, G. Munhoven2, J.L Probst1 and S.
Kempe3

1Centre de Gochimie de la Surface / CNRS,1, rue Blessig, F-67084 Strasbourg, France

2Laboratoire de Physique Atmosphrique et Plantaire,5,
avenue de Cointe, B-4000 LiAge, Belgium

3Geologisch-Pal4ontologisches Institut, Technische Hochschule
Darmstadt,
SchnittspahnstraE1e 9, D-64287 Darmstadt, Germany

Continental erosion is a permanent sink for atmospheric CO2
that is consumed both by photosynthesis and chemical rock
weathering, and that is transfered respectively as dissolved
organic carbon (DOC), particulate organic carbon (POC), and
dissolved inorganic carbon (DIC) to the oceans by rivers. For
all of these carbon forms, the major factors that control the
fluxes on a global scale have been determined in order to
establish global and regional budgets. Because drainage is the
main controlling factor for river fluxes, a similar approach
was done to relate this parameter to other climatic and
morphologic factors. This allows to estimate carbon fluxes for
different climatic scenarios, as e.g. predicted by General
Circulation Models. River fluxes of carbon were taken from the
literature, and the climatic, biologic, and geomorphologic
characteristics over the continents were extracted from
various computer databases. For this study, two global
datasets for drainage intensity and continental lithology were
created on the basis of maps published by UNESCO and
FAO/UNESCO.

DOC fluxes are mainly related to drainage intensity, basin
slope, and the amount of carbon stored in soils. POC fluxes
are calculated as a function of mechanical erosion rates,
which are globally coupled to the product of drainage
intensity, rainfall variability, and basin slope. The amount
of atmospheric CO2 consumed by the chemical weathering of rocks
is related to lithology together with the drainage intensity
in the river basins. For a given drainage intensity, the
greatest CO2 consumption occurs on carbonate rocks, followed by
shales, basalts, evaporites, acid volcanic rocks, and sands
and sandstones. Plutonic and metamorphic rocks show the lowest
specific CO2 consumption.
Drainage intensity depends on the amount of precipitation. The
runoff coefficient, which is the percentage of the
precipitation which runs off by rivers, is well correlated
with a simple climatic index formed by the ratio of mean
annual temperature over mean annual precipitation. Predictions
for the runoff coefficient can be significantly improved by
including basin slope, mean elevation, and rainfall
variability as additional parameters.
Our empirical models yield a total figure of about 0.8 Gt of
carbon going to the oceans every year. About one seventh of
this carbon is of lithologic origin (carbonate dissolution),
and the other part originates from atmospheric/soil CO2 (FCO2).
Fromthe latter, 34 % are discharged as DOC, 28 % as POC, and
38 % as DIC. About 45 % of organic FCO2 and about 48 % of
inorganic FCO2 are discharged from tropical wet regions. The
next important climate zone for inorganic FCO2 is the temperate
wet region, where the relative importance of inorganic FCO2 in-

creases because of the abundance of large carbonate areas. 23
% of global inorganic FCO2 are exported from this region, but
only 15 % of global organic FCO2. For organic FCO2, the tundra
and taiga climate is more important because of the organic
rich soils in the northern latitudes. The major part of DOC is
discharged into the Atlantic Ocean (37 %), whereas the bulk of
POC and of atmospheric DIC are discharged into the Indian and
Pacific Oceans (59 % and 50 %, respectively).

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

CHANGES IN GLOBAL TERRESTRIAL CARBON INFLUX
DIRECTLY ASSOCIATED WITH AN INCREASE IN
ATMOSPHERIC CO2 CONCENTRATION

Y. Luo and J.T. Ball
Biological Sciences Center
Desert Research Institute, Reno, NV 89512 USA.
We use leaf-level physiology to estimate the additional amount
of global terrestrial carbon influx (P_G) stimulated directly
by an increase in atmospheric CO2 concentration (C_a). We
examined leaf photosynthesis (P), focusing on its normalized
response to a small change in C_a [delta3DdP/(P dC_a)].
Although the response of P to C_a (dP/dC_a) varies greatly
with light, nutrients, and species, normalization of dP/dC_a
to P [through manupilating Farquhar et al. (1980) photo-

synthesis model] eliminates these environmental effects. It
suggests that delta is an invariant function of CO2
concentration for C_3 plants across species and environmental
conditions.
We tested this proposition with 9 sets of experimental data
which included 12 species, photosynthetic responses to
measurement conditions of light and temperature, as well as to
growth in several levels of light intensities, temperature,
nitrogen, phosphorus, water stress, and CO2 concentrations.
Absolute rates of leaf photosynthesis differed by over 10 fold
among these species and due to variable measurement conditions
and growth environments. Values of delta calculated from these
datasets, however, converged to a narrow range defined by the
upper and lower limits of the delta function. Analysis
indicated that 97% of the variation in 286 experimental values
of delta pooled from the 9 datasets can be explained by the
theoretical delta function. It confirms that delta (1) is
insensitive to variation in photosynthetic capacities between
species and between plants acclimated to different growth
environments; (2) varies within theoretical limits as mea-

surement light and temperature varies; and (3) is a function
of CO2 concentration.
The consistency of the delta function is potentially useful in
estimating the increment of carbon influx through C_3 plants
into global terrestrial ecosystems associated with the annual
increment in C_a (about 1.5 ppm). Assuming that the 1.5-ppm
increase in C_a does not cause adjustments in leaf
photosynthetic properties, photosynthetic carbon assimilation
will increase by 0.17 - 0.37% for all C_3 plants, regardless
of growth environments. Whether or not these small, constant
increments are additive within plant canopy and over various
spatial scales is yet to be tested. If the increments are
additive over the global terrestrial ecosystems, global
photosynthetic carbon influx will increase by 0.18 to 0.39 Gt
(1 Gt 3D 10^15 g) yr^-1, assuming that PG 3D 120 Gt yr^-1 and
that 85% carbon influx into global terrestrial ecosystems is
through C3 plant assimilation.
The product delta x C_a should be the photosynthetic beta
factor (beta_p). Values of the biotic growth beta factor used
in a variety of global carbon cycling models are well within
the predicted beta_p range.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


DEVELOPMENT AND TESTS OF THE BIOSPHERE-ATMOSPHERE
INTERACTION MODEL( BAIM) FOR USE WITHIN
PHYSICAL CLIMATE MODELS

K. Mabuchi1, Y. Sato1, H. Kida2, N. Saigusa3 and T. Oikawa3

1Meteorological Research Institute, Japan Meteorological
Agency,
1-1 Nagamine, Tsukuba, Ibaraki 305, Japan

2Department of Geophysics, Faculty of Science, Kyoto
University,
Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto 606-01, Japan

3Institute of Biological Sciences, University of Tsukuba,
1-1-1 Tenodai, Tsukuba, Ibaraki 305, Japan

To construct a climate model that includes biophysical and
biochemical processes of the terrestrial ecosystem, a new land
surface process model (The Biosphere-Atmosphere Interaction
Model: BAIM) for use within physical climate models was
developed and is being tested. The ecosystem modelled in BAIM
consists of two canopy layers and three soil layers. The
prognostic variables are the temperature and the interception
water of the canopy layers and the temperature and the wetness
of the soil layers. BAIM can also deal with the accumulation
and melting of snow on the ground and the freezing and melting
of water in the soil. BAIM can estimate not only the energy
fluxes (sensible and latent heat) but also the carbon dioxide
flux connected with the absorption and respiration of carbon
dioxide by the ecosystem. In the model the realistic
descriptions of photosynthesis for C3 and C4 plants are
adopted. The canopy resistance that is closely concerned with
the water vapour and carbon dioxide fluxes between the
ecosystem and the atmosphere is obtained from the integration
of a leaf stomatal resistance calculated from a consideration
of the enzyme kinetics and electron transport properties of
chloroplasts and the ambient environmental parameters.

Some off-line test results of BAIM are presented. On the off-
line tests, the required forcing data are temperature , water
vapour pressure, wind speed and concentration of carbon
dioxide at the reference level; precipitation; the downward
longwave and shortwave radiation fluxes, and integration time
step interval is one hour. The off-line tests for C3 and C4
plants were done using the data observed at the forest site
(C3) and at the grassland site (C3 and C4). Generally speak-

ing, on those test results, BAIM could successfully reproduce
the latent and sensible heat fluxes and the carbon dioxide
flux between the ecosystem and the atmosphere.
>>>>>>>>>>>>>>>>>>>>>>>>>>

LOW FREQUENCY OSCILLATIONS IN REGIONAL TEMPERATURE-PROXY
RECORDS AND IMPLICATIONS FOR RECENT CLIMATE CHANGE

N. Mahasenan1, H. Dowlatabadi1 and Robert G. Watts2

1Department of Engineering and Public Policy,
Carnegie Mellon University, Pittsburgh PA 15213, USA

2Department of Mechanical Engineering,
Tulane University, New Orleans LA 70118, USA

The global-mean surface temperature has inherent variability
on all time scales. The causes of this variability can be both
internal (eg. The El Nino Southern Oscillation or ENSO) and
external (eg. aerosol and greenhouse gas forcing).
Distinguishing natural climatic variability from the observed
0.5F8C warming since the mid-nineteenth century is crucial to
understanding the response of the climate system to the
greenhouse effect.

Singular spectrum analysis (SSA) of global surface temperature
records has indicated a warming trend since about 1900,
besides interannual and interdecadal oscillations. The
comparitive brevity of these records has prevented detection
of lower frequency variability. Temperature-proxy records, in
the form of oxygen isotope anomalies in ice-cores and corals,
however, provide records that go back a few hundred to several
thousand years. These records provide a useful tool for
identifying periodicites in the temperature signal, and
improve our ability to predict future trends in the global
temperature.

Here, we present results from SSA of four different regional
long-term records of oxygen isotope anomalies. The records are
from the Dunde Ice Cap in China, Pacific corals from the
Galapagos Islands and Vanuatu and from the Quelccaya Ice Cap
in Peru. They are shown to be consistent with regional global
temperature records. We find consistent oscillations of period
160-170 years in the proxy records. This oscillation could
account for a significant portion of the observed warming
trend in global temperatures. Simple Fourier analysis of
ice-core records of oxygen isotope anomalies from Greenland
has indicated oscillations of similar time scales. Higher
frequency oscillations observed in the proxy series compare
favorably with those reported from analyses of global
temperature time series. The phase of the long-term
oscillation also seems to affect the severity of higher
frequency temperature fluctuations like ENSO. Implications of
this long-term oscillation in the interpretation of recent
climate change, and its effect on ENSO-related impacts on
human activity is discussed.

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PLEISTOCENE CARBONATE SEDIMENTATION ALONG
WESTERN INDIAN COAST - PALEOCLIMATOLOGIC IMPLICATIONS
AND SEA LEVEL CHANGES

Kotha Mahender

Department of Geology, Goa University, Goa 403 205 INDIA

Quaternary carbonate deposits characteristic of high energy
shorelines are known from Bermuda, Bahamas, Yucatan,
Mediterranean Coast, Trucial Coast, India etc. These deposits,
referrred to as Carbonate Eolianites, form a common and
conspicuous facies of Pleistocene and Holocene and provide a
wealth of information on the fluctuating Quaternary Climates
and sea level changes. Indian subcontinent having a vast coast
line with a varied Quaternary history, exposes along Gujarat
coast, some of the excellent outcrops of such Quaternary
carbonate rocks, popularly known as "Miliolitic" carbonate
deposits with varied field character and textural parameters
have been studied in the past to evaluate the fluctuations of
pleistocene climate and sea-levels. The present paper
documents the microfacies and diagenetic character of the
Pleistocene carbonate carbonate accumulations of Gujarat
Coast, Western India to infer Quaternary palaeoclimatological
and palaeoenvironmental aspects.
The porous, fine-medium grained, Western India to infer
display large-scale cross-stratification with high angle fore
sets dipping chiefly to landward. The tops of carbonate duens
often show signs of karstt erosion and at several places
development of soil horizon/hard, dense caliche crust. The
benthonic foraminifera dominated limestone is a pelletal
packstone to grainstone, the constituents off which arae
cemented by medium to coarse, clear sparry calcite cement of
various forms and shapes. The limestone is characterized by
early stage cemeents and othere diagenetic fabric
characteristic of vadose zone involving dissolution,
cementation, neomorphism and micritization.
Critical analysis of the field data and compositional and
diagenetic characteristics points to a Middle Pleistocent high
sea (25ml as1) which subsequently regressed to a level as low
as 150m bsl at the close of late Pleistocene which corresponds
to the formation off these carbonates and their sub-aereial
exposure resulting the present topography of Gujarat Coast,
India.

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MODELING OF GLOBAL NET ECOSYSTEM PRODUCTIVITY
AND SENSITIVITY TO INTERANNUAL CLIMATE FLUCTUATIONS

P.Maisongrande1, A.Ruimy2, P.Ciais3, and G.Dedieu1

1Centre d'Etudes Spatiales de la Biosphere, Unit
CNES-CNRS-UPS,
18 Avenue Edouard Belin, bpi 2801, 31055 Toulouse, France

2Carnegie Institution of Washington 290 Panama Street,
Stanford, CA 94305, USA
3Laboratoire de Modlisation du Climat et de l'Environnement,
CEA, CE Saclay, Orme des Merisiers, 91191 Gif-sur-Yvette,
France

A diagnostic model for estimating global Net Primary
Productivity (NPP) has been forced by 6 years (1986-1991) of
weekly NOAA-AVHRR Global Vegetation Index (GVI).
Interannualvariations of NPP have been related to the effects of
interannual climate fluctuations (temperature, precipitation),
with special emphasis on El NiA4o events. Various perturbing
effects such as orbital and calibration drifts, atmospheric
and directional effects limit the use of remotely sensed data
and are briefly discussed.

Once NPP is estimated, we need to assess heterotrophic
respiration (SR) in order to derive Net Ecosystem Productivity
(NEP) and net carbon fluxes. We used parametric relationships
between SR and climate variables, as proposed by Raich and
Schlesinger (1992) for main terrestrial ecosystems. The
resulting NEP estimates are compared to NEP derived from runs
of an inverse atmospheric tranport model (Ciais et al., 1995).
The two zonal distribution of NEP are in good agreement. In a
second step we used NEP derived from inverse atmospheric
transport to estimate Q10 values for northern hemisphere
biomes.
Finally, we present variabilities of NEP and SR in response to
interannual fluctuations of temperature and precipitations.


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Natural Variability of Climate and the Detection of the Global Warming

S. Manabe and R.J. Stouffer

Geophysical Fluid Dynamics Laboratory/NOAA Princeton University, Princeton, New Jersey 08542 U.S.A.

This presentation explores the variability of climate obtained from a 1,000 year integration of a coupled atmosphere-ocean-land surface model with relatively low computational resolution. It shows that, with the exception of the eastern tropical Pacific, the model simulates reasonably well the observed variability of surface air temperature with annual to interdecadal timescales.

It shows that such variability is essentially generated though the forcing of the mixed layer ocean and land surface by the atmosphere. However, in certain oceanic regions of high latitudes, the interaction between the atmosphere and deep ocean through convection and thermohaline overturning induces sea surface temperature variation with decadal to centennial time scales.

Based upon the results presented above, the detectability of the global warming is discussed. The present study suggests that a sustained, warming trend of significant magnitude such as that observed since the end of the last century is not caused by the interaction among the atmosphere, oceans and land surface. Instead, it may have been induced by a long term trend in thermal forcing resulting from the changes in solar irradiance, atmospheric greenhouse gases, aerosol loading, and so on.

Finally, we assess the prospect for future improvement of coupled ocean-atmosphere models and their application for the study of past, present and future climates.

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#295

VARIATIONS AND CHANGE IN SOUTH AMERICAN STREAMFLOW

J.A. Marengo

Centre for Weather Forecasting and Climate Research (CPTEC), National Institute for Space Research (INPE)

12630-000 Cachoiera Paulista, Sao Paulo, Brazil

Long-term hydroclimatological records in tropical South America have been analyzed in order to determine whether or not there have been significant changes in the hodrological cycle. Streamflow data from several rivers in Peru, Brazil, Argentina and Venezuela, as well as rainfall in Northeast Brazil have been used here for the study of long-term and interannual variations on hydrological conditions in different regions of South America. The Mann-Kendall statistical test is applied to the historical streamflow annual series in order to detect trends or changes in the mean. The Student t-test is also applied to study the relationship between interannual variability and the magnitude of change an length of data required to identify a statistically significant trend.

It follows from the statistical analysis of the currently available historical river data set that there is no clear evidence of trend or change in the mean streamflow of South American rivers resulting from a climate change, even though significant trends towards drier conditions have been found for rivers in the Northwest coast of Peru and in eastern Brazil. Interannual variations characterized the Hydrology of tropical South America, in association with the with extreme phases of the Southern Oscillation. The change required to identify a statistically significant variation in the mean is directly proportional, to the interannual variability. The effects of Amazon deforestation are not noticeable on the 1903-92 interannual variability of the Rio Negro series at Manaus nor in rainfall time series.

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CLIMATIC EFFECTS OF BIOMASS BURNING
Susan Marshall1, John A. Taylor2, Steven D. Prager3, Robert J.
Oglesby4,
Jay W. Larson5, and David J. Erickson III6

1Dept. of Geog. and Earth Sci., UNC-Charlotte, Charlotte, NC
28223, USA
2Centre for Resource and Environmental Studies,
Australian National University, Canberra, Australia
3Dept. of Geog. and Earth Sci., UNC-Charlotte, Charlotte, NC
28223, USA
4Dept. Earth and Atmospheric Sciences, 1397 CIVL Bldg.,
Purdue University, West Lafayette, IN 47907 USA
5Centre for Resource and Environmental Studies,
Australian National University, Canberra, Australia

6Atmospheric Chemistry Division, NCAR, Boulder, CO 80307, USA

Biomass burning occurs as a result of natural causes or
through the actions of humans. The indirect cooling effect of
the smoke released from deforestation has, however, received
little attention. According to the model of Taylor and
Zimmerman (1990), more than half of the emissions will occur
in the southern hemisphere, which implies that biomass burning
may be the most significant anthropogenic source of
particulates affecting climate in that hemisphere.
The smoke plumes that result from biomass burning are
dramatically obvious on visible wavelength satellite images
(nearly indistinguishable from low and mid-level clouds), but
are virtually absent on infrared wavelength images. This is
because the particulates strongly reflect short wave (solar)
radiation, but are largely transparent to infrared
(terrestrial) radiation. Biomass burning smoke plumes should
therefore have a clear net cooling effect on the system.
We are making a series of GCM simulations with the NCAR CCM2
in order to examine further the consequences of biomass
burning. We take a three-pronged approach to our study; (1)
Examining only the short-wave forcing fo the smoke clouds by
imposing 'clouds' in the model whenever biomass smoke was
predicted by the Taylor and Zimmerman model. These smoke
'clouds' were only allowed to interact with the short-wave
radiation scheme in the model. (2) Allow the smoke to modify
the optical properties of the existing cloud. The aerosols
emitted by the biomass burning are generally small (in the
range from 0.1 to 0.2 5m), resulting in a reduction of the
effective (mass) droplet radius, thereby affecting the short
wave optical properties of the existing clouds (see Woods et
al 1990). (3) Advection of smoke using semi-Lagrangian
transport capability of CCM2. Though initial testing of smoke
transport using the ANU-CTM shows the biomass smoke to remain
fairly localized, the advection of smoke on the prevailing
winds can extend the short wave effects of the clouds
downwind, and can also increase the mean vertical height of
the smoke clouds. Preliminary results suggest strong local
coolings (2-4F8C or more) in the immediate region where biomass
burning occurs, and somewhat reduced regional coolings. Little
far-field effect is seen.

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MODELING THE MINERAL DUST EMISSIONS IN ARID REGIONS

B. Marticorena1, G. Bergametti1, Y. Callot2, M. Legrand3, C.
N'Doume3
1LISA, Universits Paris 7-Paris 12, URA CNRS 1404,
Centre Multidisciplinaire, 61 av.Gal De Gaulle, F-94010
Crteil Cedex, France

2URBAMA, Universit de Tours, Site Loire,
BP 1028, F-37012 Tours Cedex, France.

3LOA, UST de Lille, F-59655 Villeneuve d'Ascq Cedex, France.
Tropospheric aerosols act on the radiative budget of the
Earth. Mineral dust represents 50 % of the total annual mass
of particulate matter emitted into the atmosphere. In the next
future, this amount of mineral dust could be modified by both
higher human land uses and by climatic changes able to
increase in some regions the extent of dust sources.
To take into account such possible changes in the dust
emission rates, an explicit physical scheme of dust emission
which express dust fluxes as a function of the relevant
meteorological and surface features parameters has been
developed. This dust scheme production has also be designed to
be usuable for global scale model in order to provide an
efficient dust source in modeling of the climatic effect of
mineral aerosol.
The confidence level of this dust emission scheme has been
evaluated through different ways:

- the physical scheme, has been matched with precise
microscale set of data: this model is based on a
parameterization of the threshold wind velocities
depending both on the soil type (textural and
mineralogical characteristics) and on the partition of
the wind energy between the roughness elements and the
erodible surface. Results show that experimental friction
velocities and measured fluxes are well reproduced in
various situations.

- the large scale applicability has been tested, for the
Saharan desert, by comparing day to day simulated dust
fluxes over one year with similar Infra Red Meteosat
satellite observations. The results show that the model
reproduce with a high level of confidence the
spatio-temporal variability and the intensity of dust
emission over this area.

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AN INVESTIGATION OF THE UV RADIATION ENVIRONMENT
IN ANTARCTICA AND ITS EFFECTS
ON THE TERRESTRIAL ANTARCTIC BIOSPHERE

T.J. Martin, B.G. Gardiner, D.D. Wynn-Williams

British Antarctic Survey, High Cross, Madingley Road,
Cambridge CB3 0ET, UK

The Antarctic provides a unique opportunity to investigate the
response of terrestrial and marine microorganisms to the
increased biological stress of higher levels of UV radiation.
The severe annual depletion of ozone above Antarctica gives
rise to significantly enhanced levels of UV radiation during
each austral spring, and in recent years UV-B irradiance at
ground level during this period has exceeded the maximum
values experienced at the summer solstice. The tolerance of
Antarctic species to UV exposure is dependent upon the
effectiveness of repair mechanisms, avoidance strategies and
protective pigments in limiting damage. However, the potential
ecological consequences of enhanced radiation levels are
further complicated by erratic variation in the radiation
climate due to changes in cloud cover and aerosol turbidity in
addition to the effects of fluctuations in ozone column depth
and the screening effects of snow and ice.
A comprehensive radiative transfer model is employed to
investigate the radiation environment in Antarctica. The model
is based upon the discrete ordinate solution to the equation
of radiative transfer. It allows efficient and reliable
calculation of spectra at ground level for any given
atmospheric profile, and is valid for a spherical atmosphere
to maintain accurate results at the large solar zenith angles
typical of high latitudes. The optical properties of aerosol
and cloud particle distributions are calculated directly from
Mie theory for complete generality.
This model is used to provide a description of both the
quality and quantity of UV radiation in Antarctica under a
range of atmospheric conditions. With monochromatic action
spectra, biologically weighted doses may then be calculated
for various biochemical and metabolic processes susceptible to
UV damage. The results will assist in the interpretation of
protective responses observed in the field and provide data
for the realistic simulation in the laboratory of fluctuations
in UV radiation.
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MODELING THE INORGANIC PHOSPHORUS CYCLE OF
THE NORTH PACIFIC USING AN ADJOINT DATA ASSIMILATION MODEL
TO ASSESS THE ROLE OF DISSOLVED ORGANIC PHOSPHORUS
R.J. Matear and G. Holloway

Institute of Ocean Sciences, P. O. Box 6000
Sidney, BC, Canada, V8L 4B2


An adjoint model was developed for the conservation of a
tracer and used to assimilate phosphate observations from the
North Pacific. The adjoint model estimated optimal values for
new production, remineralization length scale of particulate
organic matter (POM), phosphate field and circulation field.
Allowing no modifications to the circulation field computed by
the Hamburg Large Scale Geostrophic (LSG) model, we could not
produce optimal estimates of new production and phosphate
concentrations that were consistent with the observations.
However, by allowing modifications to the LSG model's
circulation field the adjoint model demonstrated that a model
with only POM transport of organic matter produced results
which were consistent with observations of new production and
phosphate concentrations. In this model, only small
modifications to the circulation field were required to
produce consistent estimates of new production and phosphate
concentrations. This showed that the modeled phosphate field
and new production were sensitive to small changes in the
circulation. Furthermore, the data assimilation model implied
that dissolved organic phosphorus did not necessarily play an
important role in the cycling of phosphate in the North
Pacific.

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TOTAL MIGRATION AND TRANSFORMATION OF SILICON
IN BIOGEOCHEMICAL SUBSYSTEMS

V.Matichenkov, E.Bocharnikova

Institute of Soil Science and Photosynthesis RAS, 142292,
Pushchino, Russia

Si is the one of the most widely distributed element in the
Earth. It is often accepted that silicon is inert, slightly
mobile, and doesn't play any important role in the life of
living organisms. There are however, many indications that Si
can play an important role in certain biogeochemical
processes. Silicon is listed in two places in classifications
of elements with reference to mobility: as being mobile and as
inert. Soluble silicon substances play an important role in
geochemical and biogeochemical processes in terrestrial and
ocean areas.
The total biogeochemical cycle of Si in the environment is
characterized by a transport of various silicon substances:
liquid (monosilicic acids, polysilicic acids, silicic acids
with 2 or 3 atoms of Si, complexes with inorganic compounds,
silicates, organosilicon compounds and complexes with organic
substances) and solid (various silicates, amorphous silica and
quartz). This transport is provided by water, winter, living
organisms and increasing human activity (agronomy, forest
industry, metal industry, energetic industry). Silicon com-

pounds may take part in many physical-chemical processes such
as solution, adsorption-desorption, precipitation,
dehydratation, salt formation and formation of complexes with
organic and inorganic substances. The total proportion of
transforming and moving silica has not been adequately
explored. The main factors of silica involving in biogeoche-

mical cycles are dissolution (7.36 million tons of Si from
terrestrial area every year) and uptake by living organisms
(460 million tons of Si annually). In natural waters (ocean,
rivers, subsurface waters, soil, atmosphere waters) the
soluble silicon substances were transforming, precipitating,
influencing on organic and inorganic compounds and accumu-

lating in bodies of living organisms. Six biogeochemical
subsystems with different silicon cycles were distinguished
(soil-plant, badlands, subterranean, atmosphere and aquatic
(sea, river and wetland) systems). All these subsystems have a
close relationship between themselves and form the total
biogeochemical cycle of silicon in nature.

The Si content and its annual increase present in each
biogeochemical subsystem. The movement of silicon compounds is
realized by solid, liquid and biotic forms. The scheme Si
forms and directions of their motion between various
biogeochemical subsystems showes that the total Si cycle is
composed of several partial subcycles with general direction
of silicon move from terrestrial are into ocean. The
investigations displayed the paramount importance of silicon
in global biogeochemical processes and for living organisms
first of all. It is necessary to include the silicon parameter
in global biogeochemical model, because ignoretion of Si
influence may result in ecological catastrophes.

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GLOBAL DATA BASES ON LITTER PRODUCTION,
POOLS AND LIFETIMES

E. Matthews

SSAI, NASA Goddard Institute for Space Studies
2880 Broadway, New York, NY, 10025, USA

The primary focus of this work is to improve understanding of
the current status, composition, distribution, and lifetime of
litter carbon pools and fluxes through the development and
evaluation of a suite of geographic estimates of these
parameters. The data are designed to serve as validation data
and in some cases, as initialization data, for the growing
suite of carbon/biosphere/biochemistry models. We employed an
integrated approach, estimating related pools and fluxes using
a variety of data-based and modeled-based techniques. The
analysis includes direct estimates and indirect, or proxy,
estimates of litter production and pools; steady-state
lifetimes are estimated from the other two. Despite the large
body of published litter measurements for individual sites,
there are few global data sets with which to compare these
results. In addition, although biosphere etc. models char-

acterize the composition and dynamics of inputs, decay, and
transfers of litter materials among pools of organic matter in
litter and soils, the definition of pools is usually vague,
and distributions and characteristics of modeled litter fields
are rarely presented. Reporting global means or totals for
litter production, litter pools or complementary parameters,
as frequently done in model studies, does not provide
sufficient information to diagnose causes underlying the
differences among fields from various sources. In fact, global
similarities can obscure regional and ecosystem differences.
Because the litter pool is relatively unconstrained in models,
the major input to litter production (NPP) and especially the
dominant output (soil respiration) remain less constrained
than required to evaluate small interannual imbalances in
ecosystem fluxes such as transient carbon storage in litter.
By encompassing both spatial distributions and magnitudes,
along with numerous field measurements, the approach presented
here has begun to guide rejection and/or endorsement of global
and regional estimates of litter fields. It is hoped that
availability of this coherent body of measured and modeled
data will prompt closer investigation of the litter fields
output from more sophisticated process models and thereby
contribute to reducing uncertainties in modeled fields and
their predicted changes.

More than 1300 measurements of litter production, pools and
lifetimes, along with characteristics of the measurement sites
and other identifying features, were integrated from ~10 major
source compilations. These measurements were evaluated for
duplicate site reports, errors, etc., and combined into a
standard format to create a new baseline data set. The final
data base encompasses ~750 measurements of total litter
production, ~275 measurements of leaf litter production, 185
measurements of both leaf and total production, and ~265 mea-

surements of aboveground forest litter pools. In addition,
several hundred measurements of soil respiration, coarse woody
detrital biomass and input, and litter decomposition rates are
part of the data set.

A series of regression models of litter production (direct)
and its proxies (indirect) (e.g., net primary productivity,
soil respiration) were implemented. Ecosystem composites of
litter production and litter pools from commonly-referenced
publications, as well as ecosystem means derived from the
measurement data, were extrapolated globally using a digital
vegetation data set (1F8 resolution). A modest series of
data-based and model-based estimates of global litter pools
was also implemented in this study.

Historically, global estimates of litter production have
ranged from 54 to 139 Pg (Pg3D1012g) dry matter/yr equal to
27-70 Pg C/yr. A series of ten global distributions of litter
production will be presented based on implementation of
regression models (production against latitude, altitude, and
various climate-derived parameters), novel indirect techniques
based on soil respiration, and extrapolations based on the
newly compiled measurements.

Litter pool estimates are more difficult to evaluate because
data are extremely scarce and the feature itself is difficult
to define. Global litter pool values reported for ~15
biosphere/carbon/biochemistry models range from 94 to 392 Pg
dm (45-195 Pg C). The range for this poorly defined litter
field has not narrowed over time. The small series of global
litter pool estimates will also be presented.

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A PRELIMINARY PALAEOCLIMATIC INTERPRETATION OF
GROUNDWATER LATERITE AND
CALCRETE IN SOUTHEASTERN BOTSWANA

M.J. McFarlane1, F.T.K. Sefe1 and A. Gieske2

1Department of Environmental Science, University of Botswana

2Department of Geology, University of Botswana

Study of the palaeoclimatic history of Botswana has focussed
heavily on the north and west of the country, on the old
shorelines of the Makgadikgadi system. Their interpretation in
terms of pluvials is complicated in a tectonically active
area. Timing of the changes is heavily dependent on C isotopic
dates from surface exposures or near-surface occurrences of
calcrete, which suffer from a 'repeated solution and
deposition' effect and may be diachronous.

A new approach to the study of palaeoclimatic issues focusses
on the hardveld/sandveld boundary, the divide between the
Kalahari basin and the eastward drainage system. The divide
marks the boundary between the predominantly leaching domain,
to the east, yielding lateritic and sandy regoliths, and the
domain to the west of the divide where silcretes and calcretes
occur. Although the climatic limits of formation of these
materials are poorly defined, climatic change has resulted in
changes in the position of the boundary such that there is a
sequence or superimposition of these different materials,
inviting palaeoclimatic interpretation in a relatively stable
tectonic area.

This paper presents preliminary results of the study of
profiles exposed in an extensive system of gullies in the
Kanye area of southeastern Botswana, on the hardveld side of
the divide. Stages tentatively recognised are: (1) a sandy
clay mantle with active overturning, incorporating MSA
artefacts, interpreted as representing humid conditions; (2)
cessation of the overturning and the precipitation of a
horizon of lateritic pisoliths within the mantle, interpreted
as indicating reduced rainfall; (3) a second, lower zone of
lateritic pisoliths, reflecting further reduced and lowering
of the water-table and of the locus of the lateritic pisolith
precipitation; (4) a lower horizon of calcrete nodules,
interpreted as expressing increased aridification, weakened
leaching and further water-table lowering; (5) extremely arid
conditions expressed by desert patenation on artefacts in the
gullies; (6) a return to wetter conditions with highly
seasonal rainfall resulting in incision of valley floor by a
large "sand river"; (7) a further reduction in rainfall, still
with a highly seasonal regime, resulting in incision of the
older sandy, fluviatile sediments by a smaller "sand river",
the contemporary system.

The Timing of this sequence of stages, established by isotopic
dating of laterites and calcrete, is compared with climatic
change sequences established in neighbouring areas of South
Africa. An attempt is made to tentatively quantify the
climatic changes from the dimensions of the sand rivers and
from the changing water table positions.

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THE ROLE OF THE NITROGEN CYCLE IN THE GLOBAL RESPONSE
NET PRIMARY PRODUCTION AND CARBON STORAGE
TO DOUBLED ATMOSPHERIC CARBON DIOXIDE

A. McGuire, J. Melillo, D. Kicklighter, Y. Pan, X. Xiao
The Ecosystems Center, Marine Biological Laboratory, Woods
Hole, MA, 02543, USA
B. Moore III, C. Vorosmarty, and A. Schloss

Complex Systems Research Center, Institute for the Study of
Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824, USA

We ran the terrestrial ecosystem model (TEM) for the globe at
0.5F8 resolution for atmospheric CO2 concentrations of 340 and
680 ppmv to examine the sensitivity of net primary production
(NPP) and total carbon storage to elevated CO2. At 340 ppmv TEM
estimates global NPP of 49.0 1015 g (Pg) C yr-1 and global
total carbon storage of 1701.8 Pg C; the estimate of total
carbon storage does not include the carbon content of inert
soil organic matter. For a closed nitrogen cycle, global NPP
increases 4.0 Pg C yr-1 (8.3%) and global total carbon storage
increases 114.2 Pg C in response to doubled CO2. Although the
global NPP and carbon storage responses are larger when TEM is
run with an open nitrogen cycle, a closed nitrogen cycle is
more appropriate for biospheric responses over the next
several hundred years. In comparison to any other ecosystem,
tropical evergreen forest accounts for more of the global
response of NPP (1.3 Pg C yr-1) and total carbon storage (37.2
Pg C) when TEM is run with a closed nitrogen cycle. We
examined the sensitivity of carbon cycle estimates for
tropical evergreen forest to uncertainty in the
half-saturation parameter for CO2 uptake in TEM, which is set
so that the potential uptake of CO2 increases by 37% with a
doubling of atmospheric CO2 from 340 ppmv to 680 ppmv. There
was little effect on the NPP and total carbon storage
responses of tropical evergreen forest when we set the para-

meter so that it corresponded to 25% and 50% potential
increases in CO2 uptake with a doubling of atmospheric CO2. We
also conducted a factorial experiment to examine the
sensitivity of responses to doubled CO2 for an associated 15%
reduction in vegetation nitrogen concentration. For doubled
CO2, the lower nitrogen requirement of vegetation biomass
causes global NPP to increase 8.2 Pg C yr-1 (16.8%), lower
decomposition rates cause global NPP to decrease 1.6 Pg C yr-1
(3.3%), and the combined reductions in nitrogen requirement
and decomposition rates cause global NPP to increase 4.8 Pg C
yr-1 (9.8%). In the same experiment, global total carbon
storage increases 250.3 Pg C for lower vegetation nitrogen
requirement, increases 72.3 Pg C for lower decomposition
rates, and increases 240.9 Pg C for the combination of
reductions in nitrogen requirement and decomposition rates.
The results of this study indicate that because of
interactions with the nitrogen cycle, a doubling of
atmospheric CO2 without climate change over the next several
hundred years will potentially increase global NPP
approximately 5 Pg C yr-1 and potentially increase global
carbon storage approximately 250 Pg C.

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Terrestrial Biosphere-Atmosphere System: A Challenge for IGBP and WCRP

Jerry M. Melillo
The Ecosystems Center
Marine Biological Laboratory
Woods Hole, MA 02543 USA

The terrestrial biosphere plays a central role in the climate and biogeochemical systems of this planet. More specifically, the exchange of water, energy and carbon between vegetated land surfaces and the atmosphere drives many planetary scale phenomena. In order to better understand global biospheric processes, and to evaluate their potential response to human activity, a variety of numerical simulation models have been developed. Generally, these models have evolved to consider the structure (e.g., vegetation cover, species composition) and function (e.g., evapotranspiration, photosynthesis) of terrestrial ecosystems independently. Three separate classes of global terrestrial biosphere models have emerged in recent years; atmospheric general circulation models (AGCMs), equilibrium vegetation modes, and terrestrial biogeochemistry models.

Most AGCMs used to study climate represent the rapid biophysical interactions between land surfaces and the lower atmosphere employ land surface models. Land surface models simulate the energy and water balance of the soil-vegetation-atmosphere system and operate globally with prescribed geographic distributions of vegetation and soil characteristics. However, changes in vegetation that may result from climate change will substantially alter land surface characteristics (e.g., albedo, rooting depth) and could produce important biogeophysical feedbacks on the climate system.

Equilibrium vegetation models have been used to examine the geographic distribution of vegetation communities and their relationship to climatic parameters. These models simulate the influence of the physical environment on: 1) the availability of plant functional types (i.e., which plants can grow and reproduce); 2) competition for resources; and 3) the emergent equilibrium vegetation cover. Models of this class have been used to simulate the global vegetation patterns and how they may differ under other climatic regimes.

Terrestrial biogeochemistry models have been used to simulate the flow of carbon and mineral nutrients within vegetation, surface litter and soil organic matter pools. These models have been used to examine the global patterns of net primary production, carbon storage and mineral uptake and their sensitivity to climate change.

The emergence of three separate classes of biosphere models makes it difficult to address complex issues of global change and terrestrial ecosystems. In particular, examining the response of ecosystems to multiple, and potentially interacting, factors and how the resulting changes in the terrestrial biosphere may influence the Earth system as a whole, requires a more integrated perspective. Also, nearly all existing biosphere models focus on the equilibrium structure and function of ecosystems; yet in order to better understand the consequences of human activity on the biosphere, the time dependent behavior of biogeochemical systems must be examined as well. Future models should be able to simulate the full range of dynamic behavior of terrestrial ecosystems, including vegetation dynamics (i.e., adjustment of vegetation cover to altered conditions), and its consequences for the global biogeochemical and hydrological cycles.

The requisite next step in model development is thus the creation of an integrated dynamic ecosystem models (DEMOs). In this talk, I will review what we have learned from recent model comparisons including the Vegetation/Ecosystem Modeling and Analysis Project (VEMAP), and from laboratory and field experiments that should guide us in our development of: 1) DEMOs; 2) help us to identify the types of experiments needed to fill key gaps in our knowledge; and 3) point to the types of data required to "check" the models.
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ENVIRONMENTAL CHANGES IN THE GANGES BASIN IN BANGLADESH

M. A. Miah, Ph. D.
Associate Professor
Space & Environmental Sciences Center
University of Arkansas at Pine Bluff
Pine Bluff, AR 71601

Northwestern part of the riverine country Bangladesh is on the verge of desertification due to India's unilateral diversion of the Ganges water continuously for about thirteen years since 1982 and off and on prior to that time for about seven years. The shortage of the natural water supply has lead to the random formation of sundunes in the Ganges and its tributaries and drying up of this giant river and its tributaries. About 40 of the 110 species of the Gangetic fishes are endangered and two species have been extinct. Additionally, abodes of many amphibians and reptiles have been eradicated. There have been tremendous shortage of irrigation water in agriculture. People are using massively groundwater for irrigation and pisciculture. This has further deteriorated the situation. Along with the depletion of the surface water resources, groundwater resource is also depleting. 50% of the handtube well that were used to lift groundwater for the sole purpose of drinking are not functioning. These tubewells used to extract from a depth of 8 meters. These are being replaced by the Tara pumps which can extract water from a depth of 12 meters. Scarcity of water has has exhausted latent heat sources. All the heat is now appearing as sensible heat. A rough estimate shows that 4 to 8 billion trillion calories of heat are produced as sensible heat because of drying of rivers, canals, lakes, floodplains, ponds, and ditches. Wetland ecology has been completely destroyed. Other than the rising summertime maximum temperatures, wintertime minimum because of the drying conditions of the soils.

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GLOBAL LANDSCAPE GIS AND DATABASE

Elena V. Milanova

Faculty of Geography, Moscow State University,
Moscow 119899, Russia


Landscape approach is very useful for realistic understanding
of future global changes. It provides a base for the
perception of the world as a system of interrelated
territorial samples with different environmental situations.
In response to this issue a hierarchical landscape
classificatory scheme is proposed for scale -dependent
landscape applications.The main points of landscape monitoring
and assessment are inventory and diagnosis of their status,
based on the landscapes' mapping and GIS.

The global level of landscape mapping has been implemented by
the group of researchers of the Faculty of Geography, Moscow
State University - an integrative World Map of Present-Day
Landscapes at the scale 1:15M has been published in English at
the Publishers "Soyuzkarta" (1994) under the sponsorship of
the UNEP. The map offers a colourful presentation of the
territorial distribution of present-day landscapes, and the
degree of their transformation under human impact.

Digitisation of this map is currently been undertaken to
develop a Global Landscape GIS and Database, with interactive
data display and query capabilities. The project is a collabo-

rative venture between the Department of World Physical
Geography and Geoecology of the Faculty of Geography (MSU) and
the Institute of Geography of the Russian Academy of Sciences.

Map units have been digitised as polygons at the original
scale and converted to the ARC/INFO compatible vector
format.The database architecture is determined by the map data
structure and is compatible with the map's hierarchical
legend. All landscape polygons are characterised by three
"indipendent" variables: Cover, Relief and Modif , that
represents the machine codes of individual natural landscape
zones, landscape orography classes, and landscape modification
degree respectively.The identifiers of these variables are
linked to the landscape attribute database that lists a set of
characteristic attribute values and value ranges for every
zone ( climatic and soil-vegetation patterns), class
(elevation ranges, erosion potentials, vertical zonality
types) and landscape modification (dominant and subdominant
land use patterns and transformation trends).

A specially developed software application allows for
interactive menu-driven data visualisation, user-defined
category selection and queries, and customised report
generalisation, as well as hardcopy and other associated
features.

The methodology of landscapes' classification based on AVHRR
1-km data is developed for landscape analysis at the regional
level for Central Russia. This will allow to produce
up-to-date land characteristic database for further research.
Classification of multitemporal AVHRR-NDVI data should have
advantages over single-date observations, through some cover
parameters required for global analyses are still likely to be
imperfectly characterised. Ancillary data, such as elevation,
climate variables, ecologi al regions are, therefore, con-

sidered critical in land cover description. NDVI values
acquired from the AVHRR satellite offer a means of objective
monitoring of vegetation cover considered to be a rep-

resentative component of landscapes through evaluating
phenological characteristics and assessing the variability of
these characteristics over large areas. A series of
preliminary classification experiments are being conducted
using AVHRR NDVI data at the regional level.

The initial conceptual strategy, through the use of geographic
information system (GIS)-based tools, will allow examination
of relationships between spatial data sets to characterize
landscapes, yet will rely upon relatively simple methods for
image segmentation.The resultant database will contain
multiple layers, including the source AVHRR and other remote
data, the ancillary data layers, and the landscape regions
defined by research.

Software basis for the Geographic Information System will have
to include tools for both vector and raster analysis. Raster
format will be used for database analysis since all the remote
sensing data is stored as a grid. At the same time vector data
may be successfully used for representation of the results as
well as some analytical operations.

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A SUCCESSIONAL GAP MODEL FOR BOREAL PEATLANDS:
INITIAL RESULTS

N. Miller1 and L. Klinger2
1Global Climate Research Division, Lawrence Livermore National
Laboratory,University of California, Livermore, CA 94550, USA

2Atmospheric Chemistry Division, National Center for
Atmospheric Research,Boulder, CO 80307, USA

We have developed a successional gap model for Boreal
peatlands as a means to (1) quantify high latitude carbon
storage, (2) describe peatland succession (Klinger et al.
1990), and (3) provide global climate models with a more
realistic sub-code for simulating boreal peatland response.
Our model is based on the gap models developed by Shugart
(1984) and Bonan (1988). The boreal forest gap model (Bonan
and Korzuhin, 1989) provided us with a basic framework for
further development. We have advanced this code such that
there are four dynamic soil layers, (moss, humus, peat,
mineral soil), a dynamic water table that perches as the peat
depth compacts and becomes impermeable, and peat forming
mosses which are a function of soil temperature, soil
moisture, and photosynthetically available radiation.
In the simulation of succession from aspen and birch to
spruce, the soil initially consists of a top layer composed of
humus and a mineral soil layer. A photosynthetically based
competition between peat-forming and non peat-forming mosses
takes place on the surface. As the peat-forming shade
intolerant moss begins to dominate, hydrogen ions are produced
by the moss and enter the underlying humus layer. The growth
of peat-forming moss occurs as a first approximation linear
growth rate which levels off after five years (Fig. 1). The
mineral soil is held fixed, while the humus layer depends on
above ground decomposition and has visible jumps due to tree
mortality.
As the peat-forming moss continues to increase in depth, the
carbon to nitrogen ratio approaches values that exceed 25 and
the pH linearly (initial approximation) decreases from 6 to 4.
These two criteria are the basis for the conditions in which
peat will accumulate. Peat growth is initially approximated as
a linear function and has been tuned here to chronosequence
data. Once the peat layer has reached a critical hydrological
response depth, 0.25m, a dynamically perched water table forms
above the impermeable peat layer (Fig. 2). Thus, two separate
water tables are operating, a groundwater table in the mineral
soil and a perched water table above the impermeable peat
layer.
At this time, we have been able to simulate process oriented
peat growth with sufficient realism that we will be able to do
a series of new simulations for high latitude carbon storage.
Similarly, this effort will provide us with an initial
simulation toward verifying Klinger's peatland succession
hypothesis. We expect to advance this model further by
incorporating more detailed biogeochemical cycling and
constraints in conjunction with the freeze-thaw mechanisms,
and hydrological processes.
References

Bonan, G.B 1988. A simulation model of environmental processes
and vegetation patterns in Boreal forests: Test case
Fairbanks, Alaska. Pub. No. 76 Inter. Inst. for App. Syst.
Analysis. 63 pp.
Bonan, G.B. and M.D. Korzuhin 1989. Simulation of moss and
tree dynamics in the boreal forests of interior Alaska.
Vegetatio, 84, 31-44
Klinger, L.F., S.A. Elias, V.M. Behan-Pelletier, and N.E.
Williams 1990. The bog climax hypothesis: fossil arthropod and
stratigraphic evidence in peat sections from southeast Alaska,
USA. Holartic Ecology, 13, 72-80.
Shugart, H.H. 1984. A theory of forest dynamics.
Springer-Verlag, New York. 278 pp.


(Fig. 1)


Figure 1. Dynamic soil layer growth for a Boreal peatland in
the absence of fires. The upper layer is moss with humus and
the bottom layer is mineral soil. Peat develops here after 250
years, once the internal constraints, carbon-to-nitrogen and
pH, are satisfied.

(Fig. 2)


Figure 2. Gravimetric soil water content for dynamic soil
layers within a Boreal peatland. As the peat layer becomes
impermeable, a perched water table forms above the peat and a
separate groundwater table is maintained in the mineral soil.
In this simulation, the groundwater in the mineral soil
becomes detached from the peatland hydrologic system after
approximately 450 years.


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ENVIRONMENTAL AND BIOLOGICAL CONTROLS OVERPLANT HYDROCARBON EMISSIONS: IMPLICATIONS FORATMOSPHERIC CHEMISTRY AND CLIMATE CHANGE

R.K. Monson1, M.T. Lerdau2, M.E. Litvak1

1Department of Environmental, Population and Organismic
Biology,University of Colorado, Boulder, CO 80309 USA

2Department of Ecology and Evolution, State University of New
York,Stonybrook, NY 11794 USA

The emission of volatile organic compounds (VOCs) from
vegetation has a profound impact on the state and dynamics of
atmospheric chemistry. The oxidation of VOCs in the tropo-

sphere can result in the production or consumption of copious
amounts of ozone (O3), the production of organic nitrates
(e.g., peroxyacylnitrate; PAN) which drives long-range
patterns in the transport and deposition of nitrogen, and
increases in the atmospheric lifetime of methane (CH4). These
interactions between vegetative emissions and atmospheric
chemistry have important implications for future climate
change -- particularly with respect to the mixing ratio and
lifetime of radiatively important trace gases (in the case of
O3 and CH4) and the deposition of nitrogen which can exert an
important control over the carbon sink strength of terrestrial
ecosystems. The emissions of VOCs typically exhibit strong
dependence on temperature -- future warming will tend to
increase forest VOC emissions. This strong temperature
dependence, and the important role of VOC emissions in
influencing some radiatively important trace gases, places VOC
emissions as an important component of climate change
feedbacks.

In this presentation, we will describe recent research results
from studies of isoprene emission from aspen trees in the
Rocky Mountains of the western US and monoterpene emissions
from pine and spruce trees in the boreal forest of Canada. The
studies illustrate the environmental and biological controls
over VOC emissions. To summarize the results, leaf carbon
supplies appear to exert an important control over certain
types of VOC production and emission. Our recent studies
across temporal and spatial gradients reveal that increases in
leaf carbon availability tend to result in increases in VOC
emissions. Other controls over VOC emission rate include
moisture availability, soil nitrogen availability, growth
light regime, damage by herbivores, and seasonal phenology
patterns. These factors influence VOC emissions through
affects on leaf carbon balance and/or elicitation of the en-

zymes involved in hydrocarbon biosynthesis. Because of the
dominant influence of temperature on VOC emissions, compared
to the other environmental variables mentioned above, we
hypothesize that future global warming will result in higher
rates of VOC emissions, creating a positive feedback on the
formation and lifetime of radiatively important trace gases.

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THE OCEANIC CARBON CYCLE OVER THE INDUSTRIAL ERA:
SENSITIVITY TO THE CIRCULATION AND TO THE PARAMETERIZATION
OF BIOGEOCHEMICAL PROCESSES

A. Mouchet

Laboratory for Planetary and Atmospheric Physics,
University of LiAge, Avenue de Cointe 5, 4000 LiAge, Belgium

A three-dimensional numerical model of the transport of carbon
in the ocean is presented. This work is one of the components
developed by our laboratory for the study of the global
contemporary carbon cycle. The fate of carbon at this time
scale relies primarily on processes occurring in the upper
layers of the ocean; hence our modeling effort concentrates on
these phenomena.
The state variables are, in the ocean, total inorganic carbon,
total alkalinity, phosphates, 13C, 14C and particulate organic
carbon (poc) and, in the atmosphere, the CO2 concentration. The
processes considered in the model are CO2 air-sea exchange, new
primary production, remineralization of poc, biologically
driven precipitation of aragonite and calcite, shell
dissolution or sedimentation (which is compensated for by
river inflows). The variables are advected by current fields
from general circulation models developed by other teams. The
fields from two conceptually different OGCMs are used to drive
the carbon model.
The influence of hydrodynamics on the response of the ocean to
the increase of CO2 emission during the industrial era is
discussed. The sensitivity of the results to the parameteriza-

tion of the processes affecting the carbon cycle in the ocean
are also tested (e.g. the average rain ratio, the spatial
variation of exchange coefficient and of proportion of
aragonite in shells).
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THE ROLE OF TERMITES IN GLOBAL ATMOSPHERIC METHANE BUDGET

James Z.A. Mugedo

Department of Chemistry, Maseno University College, Private
Bag, Maseno, Kenya


Termites are reported to emit large quantities of methane,
carbon dioxide, carbon monoxide, hydrogen and dimethyl
sulphide. Emission of other trace gases namely C2 to C 10
hydrocarbons is also documented.

We have carried out both in the field and in the laboratory
measurements of methane emissions by Macrotermes subhyalinus
(Macrotermitinae), Trinervitermes bettonianus (Termitinae),
and unidentified Cubtermes and Micorcerotermes species.
Measured CH4 field flux rates ranged from 3.66 to 98,25g per m2
of termite mound per year. Laboratory measurements gave
emission rates that ranged from 14.61 to 165.05 mg CH4 per
termite per year. Gaseous production in all species sampled
varied both within species and from species to species.
Recalculated global emission of methane from termites was
found to be 14.0 x 1012g CH4, per year. From our study,
termites' contribution to atmospheric methane content is
between 1.11% and 4.25% per year.

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KEY SOIL SUB-SURFACE PARAMETERS FOR MODELLING VEGETATION
RESPONSE TO GLOBAL CHANGE PROCESSES

Mark Mulligan and John B. Thornes

Department of Geography, Kings College,Strand, London, WC2R 2LS, UK

A great deal of research effort has been directed toward
evaluating the nature and significance of feedback processes
in global climate change research. An important component of
this feedback is the dynamic interaction between changing
atmospheric and land surface properties. It is now clear that
land surface properties strongly affect climatic processes and
climatic change is likely to have significant impact on land
surface properties and processes. Recent work has been
directed towards building complex land surface para-

meterisations (LSPs) and soil-vegetation-atmosphere transfer
schemes (SVATs). These models are linked to the lowest layers
of general circulation models and attempt to replicate the
dynamic interaction between land surface and atmosphere. LSPs
simulate the processes of heat, energy, water and turbulent
exchange, paying much attention to the importance of
vegetation to these exchanges. To date little attention has
been paid to the importance of subsurface properties on this
soil- vegetetation-atmosphere transfer, with much of the
research directed towards the measurement of surface, rather
than subsurface, properties and processes.

In this paper we argue that sub-soil effects on land
surface-atmosphere interactions are underestimated and
under-researched. Recent modelling studies by Mulligan (1995,
in prep.) and Thornes and Mulligan (1995, in prep) indicate
the strong dependence of evapotranspiration and plant cover on
key sub-surface properties of the soil in water limited
environments. Of these key properties, soil depth, soil bulk
density, stone content and texture are the most significant
and affect land surface fluxes directly, and indirectly
(through hydrological control of vegetation cover). Clearly
the greatest barrier to research in this field is measurement
of subsoil properties over large areas. The sensitivity of
SVAT type models to subsoil properties is discussed along with
a measure of the spatial variability of key subsoil properties
using ground penetrating radar (GPR).


MONITORING CHANGES OF LAKE WATER AND
VEGETATION AREA IN ARID LANDS

Y. Nakayama1, S. Tanaka1, K. Endo2 and Y. Suga3

1Remote Sensing Technology Center of Japan
7-15-17 Roppongi, Minato-ku, Tokyo, 106 Japan

2Department of Earth Science, Nihon University
3-25-40 Sakurajosui, Setagaya-ku, Tokyo, 156 Japan

3Hiroshima Institute of Technology
2-1-1 Miyake, Saeki-ku, Hiroshima, 731-51 Japan

In recent 20 to 30 years, rapid changes of water area have
been taking place in the several lakes of arid and semi-arid
areas in Asia and Africa. It is necessary to investigate
urgently these phenomena in detail with a unified method.
The process of recent changes for Aral Sea, Lake Balkhash,
Caspian Sea, Bosten Lake in central Asia and Lake Chad in
Africa was monitored, and its features were examined in this
study, by analyzing the multi-temporal satellite data. Several
images for each lake observed from LANDSAT and NOAA that were
oriented to the coordinates of a map projection were used. The
changes of water and vegetation area around the lake and its
vicinity for the 1970 to 1990 year were measured by comparing
the land cover classification images based on satellite data
with the geographical information data. Referring to the
meteorological data, the analyzed results indicated the
characteristics of changes on individual lakes. And, the
authors performed a comparative analysis of features among the
lakes.
In the region of Aral Sea and Lake Balkhash, the rapid shrink
age of water area was shown as a result of the inflow de
crease due to the irrigation expansion, because the vegetation
area was growing in the delta around the river mouth of inflow
river. The Lake Balkhash's change was smaller than the Aral
Sea's change because the expansion of vegetation area was not
so rapid as in the Aral Sea.
The rapid shrinkage of water area also occurred in Lake Chad
due to the influence of human activities and climatic changes.
The variation of vegetation area was shown in the range of
dried lake bottom, and no irrigation around the water area has
been found in contrast with the area of Aral Sea or Lake
Balkhash. On the other hand, the progress of shoreline in
Caspian Sea due to the water level rising was observed, and
the relationship between changes of the sea level and
precipitation in the inflow river basin was suggested.
In contrast with the above lakes, the variation of Bosten Lake
was a little because of the balance between inflow and outflow
volume of river water.
Finally, it was presumed that the method using satellite image
was most effective to investigate the rapid changes of lakes
in arid land.

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METHANE EMISSIONS IN SRI LANKA: A 20 YEAR PERSPECTIVE

S.Y. Namaratne and A. Kuruppu Department of Environmental Sciences Institute of Fundamental Studies Hantana Road, Kandy Sri Lanka

The total methane emissions in Sri Lanka during 1970-1985 period has risen almost linearly from 908 Gg/y to 1146 Gg/y with an average annual increase of 16.7 Gg. The major contributor to the methane emission has been the rice cultivation (53-55%) followed by ruminant animals (16-18%), open waste dumps (9-15%) and inland and coastal waterbodies (11-15%). Forest clearing (3-4%) and biomass burning (1%) have also contributed to lesser extents. However, fossil fuel combustion both in industry and transport sectors had relatively very insignificant effect on the methane emissions.

After 1985, the total annual methane emission appeared to have leveled off around 1150 Gg/y. This is mainly due to a slightly decline in the area of rice cultivation which was caused by the changes in land use patterns and the curtailing of agriculture subsidies. The emissions from ruminant animals remained more or less constant during the last two decades. The major ruminant methane sources were cattle (51-56%), buffalo (32-36%) and goat (7-12%). Even though the potential for methane production in animal waste appeared to be 7-8 Gg/y, this was not taken into account because of the non existence of wet or slurry based collection systems in the country. Emissions from waste dumps increased by about 7.5 Gg/y in par with the rise in urban population. Two factors, the siltation of lagoons and the construction of hydropower reservoirs in the 80?s showed counter effects on the release of methane from aquatic environment resulting in a small net decrease in the emission.

This study also indicated that 85-90% of the total methane emissions in Sri Lanka during 1970-1990 period originated from anthropogenic activities whereas the rest came from natural processes subjected to varying degree of human intervention. Furthermore, almost all emissions were of biogenic origin . Fossil fuels were responsible for only 0.1% of the total methane emissions.

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GREENSATs: A GLOBAL SYSTEM FOR MONITORING CLIMATE CHANGE

K. Natarajan

Space Technologies Department, Marmara Research Center
Turkish Council of Scientific Research
PK 21-41470, Gebze-Kocaeli, Turkey
A new system of "green satellites" (GREENSATs) addresses the
environmental issues involving the biosphere, hydrosphere,
atmosphere and lithosphere, taking into fold, the developing
and developed nations of the world. Such issues have engaged
the attention of the world community during the recent United
Nations Conference on Environment and Development (UNCED) held
at Rio de Janeiro in June, 1992. The GREENSATs may also be a
cluster of man-tended, man-serviced permanent space platforms
at low Earth orbit, and will be replenished during periodic
visits by the Space Transportation Systems (STS). An effective
monitoring system on a global scale is the fundamental
prerequisite for climate research. This paper discusses the
relevant aspects of utilization of the GREENSATs from the
point of view of monitoring global climate change.

Some of the issues involved in climate monitoring using the
proposed GREENSATs are:

* Radiation budget at ground level.
* Land surface processes and evaporation.
* Global hydrological cycle.
* Changes in land-use and vegetation cover.
* Transient climate anomalies linked with El NiA4o/Southern
Oscillation (ENSO) events.
* Extent of the greenhouse gases (GHGs) and the depletion
of ozone layer.
* Oceanic observations vis-a-vis climate research: heat
flux, carbon dioxide, momentum, and relevant internal
processes.
* Atmospheric observations vis-a-vis climate research:
dynamics of the atmosphere to predict the future state of
climate using general circulation models; chemistry of
the atmosphere to understand the role of gases and
aerosols in modifying the climate.

This paper addresses the considerations involved in the design
of GREENSATs, as well as the requirements such as ground
segment, sensors, data communication etc. from the point of
view of climate research on a global scale.

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THE PROBLEM OF AVERAGING AND ANOMALIES IN
INVESTIGATION OF CLIMATIC AND BIOLOGICAL CHANGES

V.V. Navrotsky

Laboratory of System Methods, Pacific Oceanological Institute
FEB RAS,
43 Baltiyskaya Street, Vladivostok 690041, Russia


The idea of climatic changes arises as a result of averaging
of the observed parameters values over rather large space-
time scales. Fluctuations of much lesser scales are taken as
anomalies.

Biological systems differ from physical ones in the respect,
that short-period environmental fluctuations with amplitudes
greater than some threshold level can lead to long-period
biological changes, which evolve and don't vanish by averaging
over climatic scales.

The key role of the ocean-atmosphere interactions in climate
changes in rather evident, the main part of the interaction
energy being accumulated in the ocean tropical parts. If we
suggest that generation of many thermodynamic anomalies takes
place in the tropical zones, then their spreading with the
help of general oceanic circulation can lead to the
significant growth of space-time scales (up to the climatic
ones) of the corresponding anomalies in other parts of the
Globe.

Thus, the problem of relations between climatic and biotic
changes can't be solved with equal averaging of the observed
geophysical and biological parameters over one large scale,
the averaging should be done over some range of scales. In
this procedure the weight function for biological processes
must take into account some unknown (in most cases) threshold
levels.

As examples, we analyze characteristics of cyclonic
activities in the Atlantic and Pacific oceans, the origins of
thermal anomalies and their relations with the ocean
bioproductivity.

While performing the statistical analysis of hidrophysical and
hydrobiological parameters we came to the conclusion, that
rather stable correlations can be obtained with of the method
of canonical correlations. The group of environmental
parameters was correlated with the group of biological parame-
ters, 6 parameters in each group. As a result we had stable
dependencies for different regions, where correlations between
individual parameters were fluctuating in a wide range.

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GLOBAL CARBON CYCLE MODELLING:
NON-LINEAR PROCESSES AND UPSCALING METHOD

B. Nemry, L. Fran7ois, P. Warnant, B. Hubert and J.-C. Grard
Laboratory for Planetary and Atmospheric Physics (L.P.A.P.)
University of LiAge, 5, Avenue de Cointe, B-4000 LiAge,
Belgium

In order to predict the response of the global climate to
possible scenarios of future anthropogenic CO2 releases,
L.P.A.P. is developing a global carbon cycle model. This model
is designed to interact with atmospheric and oceanic general
circulation models to simulate the future increases of the
atmospheric CO2 level and the associated greenhouse warming. It
includes a biosphere module and an ocean module. The ocean
module (Mouchet, this conference) uses as inputs the
three-dimensional hydrodynamical fields of an ocean general
circulation model and calculates the biogeochemical processes
in the whole depth of the ocean to supply the surface CO2
fluxes.
The biosphere module is presented here. It is forced with
observed present-day climate and couples a weather generator,
a soil hydrological model, a mechanistic model of vegetation
productivity (CARAIB, CARbon Assimilation In Biosphere) and a
parameterization of the soil heterotrophic respiration to
calculate the CO2 exchange flux between the atmosphere and the
biosphere. This flux is used as a boundary condition in an
atmopheric transport model to compare the simulated
seasonality of the atmospheric CO2 signal with measurements at
various monitoring stations.
The mechanistic approach used in CARAIB integrates different
ecological levels (from leaf physiology to the ecosystem and
the global levels) and is relatively well adapted to upscaling
studies. An important aspect is the high temporal variability
of the weather and its influence on the hydrological and
biological processes, which are largely non-linear. This
problem is addressed in the biosphere module through the use
of a weather generator. The sensitivity of the biosphere
module to such a weather generation is tested by comparing two
model runs. In the first run, the soil hydrological model is
forced with monthly values of the climatic variables and, in
the second, with stochastically generated daily values. It is
shown that the model distributions of the vegetation net
primary productivity and of the net CO2 exchange with the
atmosphere widely differ between these two runs. The effect on
the amplitude and the phase of the seasonal atmospheric CO2
signal is also discussed.

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PALAEOSTATES OF THE VEGETATION-ATMOSPHERE SYSTEM: MODEL
EXPERIMENTS ON ORBITAL FORCING AND VEGETATION FEEDBACK

N. de Noblet1, J. Foley2, M. Claussen3 and I.C. Prentice4

1Laboratoire de Modlisation du Climat et de l'Environnement,
CEA Saclay
B3timent 709, Orme des Merisiers, 91191 Gif-sur-Yvette Cdex,
France

2Climate, People, and Environment Program, University of
Wisconsin-Madison
1225 West Dayton Street, Madison, WI 53706, USA

3Max-Planck-Institut f1r Meteorologie
BundesstraE1e 55, 20146 Hamburg, Germany

4Global Systems Group, Department of Ecology, Lund University
Ecology Building, 223 62 Lund, Sweden

Iconic time periods for palaeoclimate model experiments on the
effects of orbital variations include 6000 yr BP (6 ka) and
115 000 yr BP (115 ka). The challenge of 6 ka is to account
for the patterns shown in palaeorecords of 6 ka climate and
vegetation, which include a poleward extension of the northern
forest belts and a major northward expansion of the Sahel. The
modelling challenge for 115 ka is to simulate the surface
conditions that could have led to the growth of large
continental ice sheets. Standard model experiments for 6 ka
are being carried out by many climate modelling groups as part
of the Palaeoclimate Modelling Intercomparison Project (PMIP);
several of these groups are also performing experiments for
115 ka. Simulated climates are being translated into global
maps of past vegetation patterns using the equilibrium
vegetation model BIOME, which provides a useful overall
diagnostic of climate anomaly patterns and facilitates
comparison with palaeodata. In the cross-cutting IGBP data
synthesis project BIOME 6000, palaeodata on past vegetation
for 6 ka are being converted to biomes (using a fuzzy logic
method) allowing direct comparison with simulation results
made using BIOME.
This presentation will summarize results from experiments for
6 ka and 115 ka with the LMD- LMCE, ECHAM, GENESIS and CCM2
atmospheric general circulation models, in which either (a)
the prescribed vegetation has been modified (based on
palaeodata) to indicate the extent to which biogeophysical
feedbacks might have modified the response to orbital forcing,
or (b) BIOME and the AGCM have been asynchronously coupled and
iterated towards a simulated equilibrium of the coupled
vegetation-atmosphere system using a multi-year averaging
period as a surrogate for the long-term climate to which
vegetation composition and structure respond. The general
conclusion from sensitivity experiments is that biogeophysical
feedbacks substantially amplify the response of the coupled
system to orbital forcing. In high latitudes, the sea-ice
feedback is synergistic with the biogeophysical feedback.
Comparisons with data suggest that these or other amplifying
mechanisms must be invoked to account for the magnitude of
past changes in vegetation and climate. Coupled model
experiments reinforce this conclusion and further suggest that
there may be alternative equilibrium states of the
vegetation-atmosphere system, depending on initial surface
conditions. These results imply (a) that attempts to predict
the long-term consequences of changes in radiative forcing
should take account of climate-induced changes in the
distribution of vegetation types, and (b) that a full
explanation for Holocene changes in climate and vegetation
patterns will likely require the implementation of an Earth
system model that includes the coupled dynamics of vegetation
and the atmosphere.
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THE LARGE SCALE BIOSPHERE-ATMOSPHERE
EXPERIMENT IN AMAZONIA (LBA)

Carlos A. Nobre

CPTEC, Rodovia Presidente Dutra, Km 40, PO Box 001 12.630-000
C. Paulista/SP, BRAZIL

Many scientific communities are planning to join forces to
cooperate in one of the most ambitious global change field
campaigns ever conceived, that is, The Large-Scale Bio-

sphere-Atmosphere Experiment in Amazonia, or the LBA
Experiment. The LBA Experiment will focus on two fundamental,
overarching scientific goals.
1.How does Amazonia currently function as a regional
entity? 2.How will human-induced change alter the function of the
Amazon region?

The emphasis of the first question is on basin-scale
interactions with the Earth System in the form of exchanges of
energy, water, carbon and other trace gases and nutrients via
the atmosphere and river system. It is the primary focus of
the large-scale component, with meso and local-scale component
providing plot and regional-scale validation/calibration. The
emphasis of the second question is on modifications within
Amazonia associated with replacing tropical forest with mixed
vegetation, and on indirect modification of the vegetation
gradient in areas surrounding Amazonia. It is the primary
focus of meso and local-scale component, with the large-scale
measurements and basin-scale diagnostic studies providing the
regional context. The broad objectives of LBA can be
summarized as follows:

(i) to improve our understanding of the physical and
biological processes controlling the energy, water,
carbon, trace gas, and nutrient cycles found within
Amazonia and to determine their link to the atmosphere;
(ii) to improve our understanding of how these energy,
water, carbon, and nutrient cycles might respond when
biological systems are changed (deforestation, selective
logging, agricultural management, reforestation or shifts
in species compositions) and global climate systems are
changed (increasing atmospheric CO2 concentration and
associated changes in the physical climate system);
(iii) to improve our understanding on the effects of
biogeochemical changes on the composition of the
atmosphere, including key greenhouse gases (N2O, CH4, CO2)
and species regulating the oxidizing potential of the
atmosphere (NOx, CO, hydrocarbons, O3) and on surface
water chemistry.

A conceptual design for a large-scale field experiment in
Amazonia is discussed. In a general sense, the experimental
goal of LBA is to provide the data and understanding to
improve models to the point where they can credibly address
the science objectives. In brief, the proposed experiment will
consist of two interlocking components.

Large-Scale Component: A basin-wide monitoring effort is to be
put in place and maintained for around two years. This will
consist of a network of radiosonde and surface meteorological,
rain gauge, weather radar and hydrological stations within the
Amazon Basin. These data, coupled with satellite observations
(including data from the Tropical Rainfall Measuring Mission -
TRMM) will permit a detailed description of the energy, heat
and moisture budget of the entire region and a few embedded
subregions. Under some conditions, measurements of the
atmospheric carbon budget and possibly other trace gases for
the same areas may be possible.

Meso and Local-Scale Component: Within the large-scale domain,
it is proposed that a number (five to seven) of research areas
be equipped with measurement towers that extend above the
vegetation canopy. There are to be equipped with flux
measurement (radiation, heat, moisture, momentum, CO2 and some
trace gases) equipment and will also serve as the foci for the
ecological, biogeochemical, hydrometeorological and remote
sensing studies. The measurements at these areas are intended
to provide understanding of the physical, chemical and
biological processes governing the surface radiation and
energy balance, the carbon budget and the budget of critical
trace constituents (trace gases and soil nutrients), The areas
are to be distribute around the region to obtain adequate
sampling of the ecoclimatological gradients. As far as
possible, the intention is to build on the work of the
existing network (e.g., ABRACOS). One central area, the
primary research area, is to be the focus of some detailed
studies comparing processes within and above undisturbed
forest, cleared pasture, abandoned pasture, regrowth forest
etc. These local-scale studies will be used to validate remote
sensing techniques and airborne flux measurement work which
will then permit extrapolation of the process models to larger
spatial scales and ultimately allow direct comparison with the
large-scale network results. Most of the proposed sites will
form part of two axis for ecological transects running through
the rainforest out to the Cerrado to the south and from the
rainforest to the dry shrubland to the east.


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HUMAN ACTIVITIES IN DEVELOPMENT -
FACTORS FOR THE CLIMATE SYSTEM

N.P. Nziramasanga

Southern Centre for Energy and Environment
Harare, Zimbabwe

Development is to do with acquisition of the ability by a
country to be able to meet its own food, energy and health
requirements. The sustainable provision of these basic
requirements paves the way for full paticipation of the
country in the global economy as a contributor and not a
liability.

The definition of basic requirements for meeting the food,
health and energy needs are changing with the developments in
the developed countries. For example the mode of energy supply
is now seriously critiqued for impact on climate change and
other environmental effects a factor which was not high
ranking a few decades ago, the development efforts of the
smaller economies are therefore burdened with the factors of
global development which are external in the short term but
local in the long term. Under this scenario the developing
coutries have to chart a route for sustainable of their
countries and societies.

It is therefore important that in designing the global models
the interaction of the various economic systems and the
dynamic evolution of the definition for sustainable
development be accounted for. The proposed paper will discuss
the development issues in Zimbabwe and how they are affected
by international treaties eg The Rio Convention, The Montreal
Protocol etc. The development issues will be centred around
energy supply and industrialisation.

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Study of Basin-Scale Ocean Circulation related to Global Chlorophyll Distribution

Atsushi Obata, Meteorological Research Institute, Japan Joji Ishizaka, National Institute for Resources and Environment, Japan Masahiro Endoh, Meteorological Research Institute, Japan

Abstract: Purpose of the study is to evaluate quantitatively cause/effect of global distribution of chlorophyll to physical environment such as ocean water circulation and surface mixed layer with the use of global circulation model. A numerical model employed is a standard global ocean circulation model driven by the climatological wind stress, surface temperature and salinity with realistic bottom topography. Embedded in the model is a closure turbulent mixed layer model. The seasonal variation of the mixed layer depth in the model, integrated for 11 years with monthly forcing in addition to the 1500 years's annual forcing run, and that in the in-situ observed temperature data are compared with the seasonal variation of the satellite ocean color data (sea surface chlorophyll concentration). At mid- or high latitudes, it is shown that shallowing of the mixed layer depth from winter to spring season in terms of the Sverdrup(1953)'s critical depth for conditioning of photosynthesis well explains vernal blooming of phytoplankton across the oceanic basins. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

PATTERNS OF TRACE GAS FLUX OVER ARCTIC LANDSCAPES

Walter C. Oechel, Steven J. Hastings and George Vourlitis

Global Change Research Group and Systems Ecology Research
Group,
San Diego State University, San Diego, CA 92182, USA

The arctic contains over 250 GT C, 90 % of which is below
ground, and is especially sensitive to changes in temperature
due to low ambient temperatures, the presence of permafrost,
and the important role of permafrost in regulating ecosystem
physiology. Warming could increase evapotranspiration, active
layer depth, and could cause the eventual loss of permafrost.
Greater evapotranspiration and drainage could increase soil
organic matter decomposition faster than primary production,
resulting in a net loss of carbon to the atmosphere.

Recent warming and drying of tundra ecosystems have increased
soil decomposition and respiration more rapidly than primary
productivity. As a result, tundra ecosystems, which were net
sinks for CO2 in the recent geologic and historic past, are now
sources. Areas of apparent CO2 loss include the IBP site at
Barrow, Alaska, wet sedge and tussock tundra sites on north
slope of Alaska, and sites on the Russian Taimyr Peninsula. A
chronosquence of post-fire tussock tundra stands on the Seward
Peninsula indicate increased CO2 loss after fire. Increased
fire frequency following global climate change would result in
CO2 loss in the fire, and increased CO2 loss to the atmosphere
for over 35 years after fire.

To better estimate large-scale CO2 flux over the circumpolar
arctic, a hierarchy of chamber, tower, and aircraft
measurements are being made as part of the NSF ARCSS LAII
Trace Gas Flux Program. Rapid GIS techniques and modelling are
being employed to help develop an approach to estimate
regional diurnal and seasonal CO2 flux. Current measurements
are being made over the Kuparuk River drainage basin, and will
be extended to the North Slope of Alaska.


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Challenges for GAIM from Studies of Past Global Changes

Hans Oeschger, PAGES

A special relationship between PAGES and GAIM is based on parameters used to reconstruct the history of climate and environment. These parameters such as greenhouse gases, products of cosmic radiation, particulate matter in the atmosphere, plant remains and relicts of geomorphological processes, reflect the complex physical-chemical-biological interplay in the Earth system. Analyzing and modeling these complexities are the subject of GAIM studies. Examples of past global change studies that pose challenges for GAIM follow.

The Physical Climate System

>From paleo research we have learned that climate change is largely the reaction to external forcings (orbital, solar variability, volcanic dust) with superimposed noise. In different natural archives, parameters have been reconstructed which in principle could be used to estimate external forcing of climate. However, characteristic internal variability plays an important role. Examples are quasi--oscillations such as ENSO and the North Atlantic and monsoonal oscillations. These phenomena change their character with changing climate, so that new types of variability may develop and play an important role in future climate. Therefore longer time series for quasi-oscillators and analysis and modeling are needed to improve our knowledge of their modulation with climatic change.

Recent studies have shown that during the last glaciation, and possibly during the Eemian interglacial, climate was instable, oscillating back and force between quasi-stable states. PAGES is working to verify this possible Eemian instability using both more ice core results and deep drilling for long continental records. Beside drilling of another core in North Greenland, Eemian continental records are especially important for documenting climatic variations which might correspond to those indicated in Greenland.

It would be helpful for GAIM to develop a quantitative understanding of North Atlantic mode switches during glacial times and to study whether, in a warmer world, the increased water vapor transport to high latitudes might induce similar changes in deep water formation and the distribution of heat over the globe. This understanding would help answer the critical question about the potential for transitions to new climatic states of the Earth system with global warming.

History of Greenhouse Gases

One of the most exciting results of ice core studies is the reconstruction of the history of atmospheric composition of greenhouse gases like CO2, CH4 and N2O. New results on isotopic variations in O2 reflect changes in the amount of continental ice. For the GAIM activities related to greenhouse gases, three periods are of special interest: 1) the variability during the past 1000 years and the increase to the present, 2) the Holocene variability, and 3) the general behavior over a glacial-interglacial cycle.

An integrating Earth system parameter is atmospheric CO2. Its concentration reflects the interaction with rocks, the terrestrial biosphere, oceanic systems, and more recently human activity. As expected, the behavior of atmospheric CO2 during a glacial-interglacial cycle is very complex. CO2 generally increases in phase with temperature during a transition from a cold to a warm period, in contrast to the delayed CO2 decrease during a transition from a warm to a cold state. Short term variability of the atmospheric CO2 concentration during the period of rapid glacial changes is critical, because one would expect an influence on atmospheric CO2 due to a change in ocean circulation and its effect on the ocean's biological pump. Both, time control and better resolution is needed to understand the processes responsible for this behaviour.

CH4 is influenced by rapid responses to variations in its sources and sinks. Comparison of the global temperature trend with its atmospheric concentration seems to show that CH4 is essentially slaved to climatic change. Nevertheless, there are differences between its behavior during the Holocene on one hand and the last glacial period on the other hand which deserve explanation by GAIM.

Isotopes in Earth Systems Information on past global changes is often based on isotopic ratios in elements like O, N, C, and H in various materials, because information about past Earth system history is best preserved by isotopic signatures in natural archives. Isotopic fractionation occurs in physical processes (diffusion, phase transition), chemical reactions, and in biological processes. Thus, the full physical, chemical, and biological interplay in the Earth system is reflected in isotopic fractionations.

PAGES is convinced that through a more systematic use of isotopes, global change research could make great progress. Initial attempts to use isotopes in the study of the water cycle and promising efforts to model isotopes in precipitation by AGCMs are welcome efforts. An urgent task is a systematic and global monitoring of gases and other atmospheric constituents, including their isotopic signatures. Data from a global network would improve the estimates of sources and sinks of greenhouse gases and help the analysis, interpretation, and modeling of recently observed anomalies in the increase of the greenhouse gases. These parameters are probably the most sensitive indicators of the impact of climatic change on atmosphere, continents, and oceans.

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INTEGRATING AFRICA IN GLOBAL CHANGE MODELLING

W. Ogana
Department of Mathematics, University of Nairobi, Nairobi - Kenya.

Modelling and data exchange are fundamental to achieving the objectives of
the IGBP Core Projects and thus advancing the scientific agenda of the IGBP.
In many global change forums concern is often expressed regarding the
uncertainty in the global models, partly due to incomplete input and lack of
appropriate data from the developing world, particularly Africa. Global
Change modelling needs to be appreciably enhanced if Africa is to make any
significant progress in global change research. The enhancement could involve
a number of options: Exposure to Africa scientists to the principles of
integrated global change models; Improvement of data communication
facilities; Convening of an African group meeting to define the continent's
priorities in modelling and data information; Data archiving; Active
involvement of African scientists in on- going and proposed global change
research projects. In addition, there will eventually be need to re-examine
school and university curricula in many African countries in order to
incorporate global change concepts.

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COUPLING A REGIONAL PRECIPITATION RUNOFF MODEL TO
GLOBAL AND REGIONAL CLIMATE MODELS
Robert J. Oglesby1, Anthony J. Jakeman2, David A. Post2, Sergei
Schreider2,
Zengquan Fan3, David P. Hansen4, John A. Taylor4 and Jay W.
Larson4
1Dept. of Earth and Atmos. Sciences, Purdue University, West
Lafayette, IN, 47907 USA;
2Centre for Resource and Environmental Studies, Australian
National University
3Dept. of Earth and Atmos. Sciences, Purdue University
4Centre for Resource and Environmental Studies,
Australian National University

The hydrologic cycle plays a fundamental role in the climate
system and is crucial to human life. Successful simulation of
this cycle is therefore: (i) a required component of models
that are used to simulate the present-day climate and to
assess possible future climatic changes and (ii) essential to
an understanding of the impacts of climatic changes on human
water supplies and other natural resources as well as
potential disasters such as floods and droughts. An ideal
surface hydrology model component should be capable, on a
global or regional basis, of producing accurate time series of
water and energy outputs based on inputs of variables such as
precipitation and temperature and physical descriptors of the
land surface. To date, climate models have used either
extremely simple bucket model representations to compute
simple evaporation or complicated, biophysical models that
attempt to simulate the poorly-known processes involved in
transpiration. Neither of these approaches makes an explicit
attempt to balance the overall water budget of the earth
system.
We have developed an entirely new approach that involves
coupling a lumped-parameter rainfall-runoff model (IHACRES)
into global (CCM2) and regional (RegCM2) climate models. This
coupled model is based on an explicit water balance that
describes the dynamical relationships between precipitation,
stream flow, and evaporation. Fast and slow track approaches
have been developed. In the fast track approach, IHACRES is
calibrated empirically to observations for specific drainage
basins, and then used in conjunction with the climate models
locally and globally to simulate evaporation and stream
discharge. In the slow track approach, physical descriptors
for important characteristics of drainage basins are being
developed that will largely eliminate the need for empirical
calibration and allow more fully predictive computations to be
made.

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MAPPING AND MEASURING BIOMASS BURNING AND SMOKE PALLS
OVER THE AMAZON BASIN
K. Oliveira
Tropical Agronomical Center for Research and Training,
7170 Turrialba, Costa Rica
The global environment is changing very rapidly, and
consequently alterating all ecosystems on Earth, due mostly to
human activities. Biomass burning is a significant agent of
these alterations. Global warming and atmospheric
contamination are some of the possible effects caused by
biomass burning. Because of lack of geographical, biological,
chemical and physical data, global change is not completely
understood and quantifyied. It is necessary to obtain precise
and consistent information on areal extent of these
alterations in order to measure and model global change.
Based on the importance of environmental change and the
significance of biomass burning, a study was undertaken at
NASA-Johnson Space Center, in Houston, USA, to map and measure
the smoke palls generated by biomass burning in the Amazon
Basin, as seen from space during the Space Shuttle missions in
the dry seasons (August-October) of 1990, 1991 and 1993, using
space photointerpretation with visual analysis and
computerized measurements.
The measurements of the areal extent of smoke palls generated
by biomass burning are of 6,146,465 km2 in 1990; 15,370,699 km2
in 1991; and 6,525,175 km2 in 1993. The map of the 1990 smoke
pall shows that parts of Brazil, Bolivia, Argentina, Paraguay
and Uruguay were covered with smoke. Because of a tremendous
increasing in the area covered with smoke, including portions
of the Atlantic Ocean, and being detected as far as in the
Falkland Islands. The map of the 1993 smoke pall shows a
substantial reduction in the area covered with smoke, becoming
similar to that one detected in 1990. It was possible to
observe that the major area of biomass burning during all the
period under study was the Brazilian State of Rondonia, caused
by extensive projects of forest conversion to agricultural and
grazing fields. It was also possible to observe that the
biomass burning follows the patterns of establishments of
agricultural and grazing areas along the major highway
networks in the Brazilian Amazon (BR-364 and Transamazonian).
This study shows that because of its areal extent, biomass
burning is an important agent of environmental alteration. The
variation in the areal extents of the smoke palls under study
is due to changes in progression of forest clearing and
biomass burning. The biomass burned in the Amazon Basin
generates smoke palls that cover significant areas in South
America, including portions of the Atlantic Ocean and the
Falkland Islands. It was not possible to identify from new
burning to shifting cultivation areas. The conversion of
forest to agricultural and grazing fields in the Brazilian
Amazon follows the patterns of development of major highways,
moving northward in the State of Rondonia and then northwest
in the State of Acre. A continuous and progressive process of
biomass burning may alterate profundly the global
environmental, affecting generations to come.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Opoku-Ankomah, Y.
Water Resources Institute
Accra, Ghana

ABSTRACT:
ASSOCIATION OF RAINFALL VARIATIONS IN GHANA WITH
SEA-SURFACE TEMPERATURES

The economy of Ghana depends on agriculture to a large extent.
However, the agriculture is predominantly rainfed and variations in
rainfall pattern can have devastating effect on the crop yields and
consequently on the economy. In an effort to predict drought,
relationships between rainfall and sea-surface temperatures (SSTs) were
examined.

Principal component analysis was used to identify dominant SST
fields in the tropical Atlantic ocean. Areal averages of rainfall for
3-month seasons were computed over a period of about 60 years. The
associations of rainfall and the SSTs were examined by linear correlations.

The computed correlations coefficients were found to be around
0.7 and is very significant. These correlations were opposite in sign to
the correlation coefficients between the Sahel rainfall and SSTs in the
same ocean region which probably suggest a different mechanism.
Associations of SSTs in a season ahead of rainfalls were also found to be
significant and thus depicting available memory in the ocean for the
climate in the region.

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THE OCEAN CARBON-CYCLE MODEL INTERCOMPARISON PROJECT

J. C. Orr1, P. Monfray2, E. Maier-Reimer3, U. Mikolajewicz3,
J. L. Sarmiento4, N. K. Taylor5, and J. R. Toggweiler6

1Laboratoire de Modelisation du Climat et de l'Environnement,
DSM, CE Saclay, CEA, L'Orme des Merisiers, B3t. 709,
F-91191 Gif-sur-Yvette, Cedex, FRANCE

2Centre de Faibles Radioactivits, Laboratoire Mixte CNRS-CEA,
L'Orme des Merisiers, B3t. 709/LMCE, CE Saclay,
F-91198 Gif-sur-Yvette, Cedex, FRANCE

3Max-Planck-Institut f1r Meteorologie, Bundesstrasse 55,
D-20146 Hamburg, GERMANY

4Program in Atmospheric and Oceanic Sciences, Princeton
University,
P.O. Box CN710, Princeton, NJ 08544-0710 USA

5Hadley Center Meteorological Office, London Rd., Bracknell,
Berkshire RG12 2SY, ENGLAND

6Geophysical Fluid Dynamics Laboratory, NOAA, P.O. Box 308,
Princeton, NJ 08542, USA

Increasingly, global 3-D ocean circulation models are being
exploited as tools to better study the complexities of the
ocean's carbon cycle. Despite the tremendous insight gained
from such 3-D modeling efforts, it is often difficult to
discern to what extent model imperfections may affect results.
Although model-data comparison is helpful, measurements are
limited. Beyond that, results from different models may also
be compared. Yet, simulations from different models are seldom
run with identical constraints, making comparison difficult.
The recent boom in the use of 3-D models to study the ocean
carbon cycle makes the need for model comparison all the more
apparent.
Improving global ocean carbon-cycle models is essential if
mankind hopes to use such models to help predict future levels
of atmospheric CO2. With this in mind, IGBP/GAIM has recently
initiated a new effort entitled the Ocean Carbon-Cycle Model
Intercomparison Project (OCMIP). This comparison effort falls
under the GAIM heading of "The Coupled Atmosphere-Land-Ocean
Carbon System", coordinated by M. Heimann. Current
participants include four modeling groups: (1) from Germany
(MPI, Hamburg), (2) from the United States (GFDL and Princeton
University, Princeton), (3) from England (Hadley Centre,
Bracknell), and (4) from France (LMCE-CFR using the ocean
model from the Laboratoire d'Ocanographie Dynamique et de
Climatologie (LODyC), Paris).
As the name suggests, the main interest of OCMIP is the carbon
cycle. Thus intercomparison will be based on the models'
current capabilities to predict both anthropogenic and natural
CO2. For the latter, the effect due to solubility and the
effect due to ocean biology will be considered separately.
Additionally, OCMIP will compare simulations of two often used
analogs for anthropogenic and natural CO2, i.e., bomb and
natural C-14. Radiocarbon is attractive because of the
existence of a global C-14 dataset (GEOSECS). Also, new data
is becoming available, namely from the the World Ocean
Circulation Experiment (WOCE). Where possible, further model
vs. data comparison will be a central focus of OCMIP,
including the ocean-atmosphere pCO2 difference and
satellite-derived surface ocean color. During this
presentation we will present the first results from OCMIP.
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CLIMATIC GLOBAL CHANGES ANDSPONTANEOUS SNOW-AND-ICE PHENOMENA

N. Osokin, V. Gokmhan, R. Samoilov, V. Zhidkov

Laboratory of Applied Glaciology and North Problems,
Institute of Geography, Russian Academy of Sciences,
Staromonetny per., 29, Moscow 109017, Russia

Climatic global changes may rapidly lead to substantial
changes in spreading and activity of such snow-and-ice natural
phenomena, as snow drifts, snow avalanches, icings, mud flows
and slush flows. This is especially important in the developed
Northern and mountain regions.
During multiyear field investigations in the Polar Ural,
mountains of Central Asia, Caucuses and Svalbard we have got a
lot of actual information on the distribution of these natural
spontaneous phenomena and about their interyear changing in
some mountain basins.
The structure of nival-glacial system is considered. We
distinguished and classified the main interrelations both
within and outside the system, for example, snow fall - snow
storm - snow avalanche - slush flow. On the basis of collected
data, satellite images deciphering in several mountain basins
we observed interlink character between climate changes and
spatial changeability of snow cover, snow drifts, snow
avalanches, slush flows, and icing. By using of existent
climate changes scenarios we propose possible scenarios of
snow drifts, snow avalanches, slush flows and icing activity
changes in Northern and mountain regions. For example, the
rising of air temperature and snowfall amount growth will lead
to decreasing of icing quantity and size, to increasing of
snow drifts, snow avalanches, and slush flows. These changes
will influence the environment and human activity in the
corresponding regions.

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DATA REQUIREMENTS FOR GLOBAL DAILY OR HOURLY
CARBON AND WATER CYCLE MODELS

R.D. Otto and G.H. Kohlmaier

Institut f1r Physikalische und Theoretische Chemie, J. W.
Goethe-Universit4t,
Marie-Curie-Str. 11, 60439 Frankfurt a.M., Germany

Many global biosphere models are driven by long-term monthly
mean climate data although they use time steps from hours to
weeks. All these models therefore apply some deterministic or
stochastic algorithm to increase the temporal resolution of
the input data. Some global models even superimpose a diurnal
course to daily average data.
Also, many different geographic databases are used with the
models which assign vegetation and soil classes to each grid
element. Further information may then be derived from the
available data.
We will compare several geographic databases and outline their
advantages and disadvantages. The simulation of other
"non-seasonal" data like rooting depth or available water
capacity (AWC) based on the available information will then be
presented.
Methods for the simulation of daily weather data and the
diurnal course of air temperature and relative humidity are
presented and tested against data from Test Reference Years
(TRY). The importance of a detailed description of daily and
diurnal courses of the driving variables is shown with a
global biogeochemical model, the Frankfurt Biosphere Model
(FBM).
We give an overview of different algorithms used and make
suggestions for some common routines and algorithms to be used
in intercomparison exercises such as Potsdam 94/95 or PILPS.

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IGBP PAGES AND CLIMATE DYNAMICS OF THE LAST 2000 YEARS

J. Overpeck1,2

1 NOAA Paleoclimatology Program, National Geophysical Data
Center
325 Broadway, Boulder CO 80303 (jto@mail.ngdc.noaa.gov)

2 Institute of Arctic and Alpine Research, University of
Colorado,
Boulder CO 80309

A major component of the IGBP Past Global Changes (PAGES) Core
Project is to "reconstruct the detailed history of climatic
and environmental change for the entire globe for the period
since 2000 BP, with temporal resolution that is at least
decadal and ideally, annual or seasonal." (IGBP Report 19).
Achieving this goal is the focus of multiple PAGES activities,
and relies on the collection of new time series, as well as
the compilation of existing data and the use of a combined
data-model approach toward understanding the causes of
observed past variability. One activity currently making
progress in the area of understanding interannual to
century-scale climatic variability of the past 2000 years is
the ARRCC (Analysis of Rapid and Recent Climate Change)
Project. This multi-institutional, interdisciplinary project
has begun the compilation of a global database for the study
of climate variability over the past centuries. Over 200 time
series have been compiled thus far, mostly from northern
hemisphere land areas, but also including some data from ocean
and southern hemisphere regions. These data suggest that the
"Little Ice Age" was not a single centuries- long period of
below present-day temperatures, but rather was a period of
multiple, globally asynchronous cold events of decade to
century duration. One of the most prominent features of the
available record is the pronounced warming that took place
since the middle of the 19th century in many parts of the
globe. Climate model (GCM) experiments have been performed to
look at the relative importance of solar, volcanic, trace-gas,
tropospheric aerosol and internal climate system dynamics as
mechanisms responsible for the observed patterns of past
change. These simulations point to "fingerprints" that can be
sought in the observational paleoclimate record as a way of
attributing past change to specific forcing. However, it is
clear that several forcing mechanisms worked together to
produce past climate variability. The experiments also suggest
that none of the hypothesized sources of natural climate
variability are likely to compensate the change likely to
occur due to elevated greenhouse gas concentrations.
The principal investigators of Project ARRCC are: Drs. Raymond
Bradley, Julie Cole, Malcolm Hughes, Gordon Jacoby, Judith
Lean, Ellen Mosley-Thompson, Jonathan Overpeck, David Rind,
and Lonnie Thompson


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J.O. Owili Institute for Meteorological Training and ResearchP.O. Box 30259 Nairobi, Kenya. Abstract Climate models have continued to improve in respect of both their physical realism and their ability to simulate present climate on large scales, and new techniques are being developed for the simulation of regional climates. Our understanding of some climate feedbacks and their incorporation in the models has improved. However, biological feedbacks, in particular global vegetation, has not been taken into account in simulation of climate change. Increased confidence in future geographical patterns of vegetation and climate change will require new simulations and improved coupled models involving plant physiological responses like canopy boundary layer conductance and transpiration rates at global scales. There will be need for development and understanding of the processes and mechanisms which control the linkages in the soil- plant-atmosphere complex. For example, the coupling of the energy exchange between the atmosphere needs to be understood for different areas with different vegetation, and for both mesoscale and seasonal and yearly time scales. There will also be need to understand how global climate change will affect vegetation distribution and how this will affect land-surface reflectivity, nutrient cycling, and sources and sinks of greenhouse gases. This paper outlines possible areas of interventions in a future global change scenario with respect to vegetation and gives suggestions for further research to improve the scope and applicability of our climate change simulation models.

Pandey, J. S. and P. Khanna,
National Environmental Engineering Research Institute
Nagpur, India

ABSTRACT
ISSUES RELATED TO BIOGEOCHEMICAL CYCLES AND MODELLING OF NUTRIENT CYCLING IN WETLANDS WITH SPECIAL REFERENCE TO GREEN HOUSE EFFECT


In order to enhance our understanding of the complex processes regulating global geosphere biosphere system, it is essential to develop
both conceptual and simulation models at local, regional and global
scales. Moreover, the role of biogeochemical cycles in describing and
understanding of key issues governing basic biophysical and biochemical
processes assumes significance even at highly resolute local scales such
as those of wetlands. although wetlands occupy only about 2 percent of
the world's area, they are estimated to contain 10 to 14 percent of
carbon. Hence, their contribution to the green house effect is important
far out of proportion to their area. This is especially in view of the
fact that worldwide there are sharply increasing trends of loads of
nitrogen and phosphorus mostly due to increased use of fertilizers. For
wetlands, inputs come primarily through hydrologic pathways such as
precipitation, surface and ground water flows, and tidal exchange.
Intrasystem cycling i.e., the cycling of chemicals such as nitrogen and
phosphorus within the wetland itself, includes pathways such as litter
production, remineralization and nutrient uptake by the plants. This
contribution discusses a computer model developed (in 'C' language) on
the basis of appropriate modifications and suitable integration of
earlier models on nutrient uptake, light availability and chlorophyll
growth. The model, with the advantage of simulation under various
combinations, helps in identification of most sensitive parameters whose
control is important from the point of view of evolving pragmatic
management strategies.



MODELS FOR DESCRIBING AND FORECASTING LAND USE -
LAND COVER CHANGES

F. Papadimitriou

School of Geography, University of Oxford
Mansfield Road, Oxford OX1 3TB, UK

Although the monitoring of land use and land cover changes has
fairly advanced over the last ten years with the aid of
satellite imagery, the global applicability of some well
defined model is still missing. This is mainly due to the
variant typologies of land use and land cover types that
render the correlation very difficult.

However, it is possible to define regional models for the
world's geographical regions.

After an overview of the models of land use/land cover change,
this paper proposes a general mathematical model that may
account for these regional changes.

By suitable manipulation of the formulas, it is possible to
derive relationships enabling to study the evolution of the
landscape structure also.

Finally, this paper shows the applicability of this model for
landscapes of the Mediterranean region.

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FLUCTUATION OF ORGANISED CONVECTION WITHIN
THE INTERTROPICAL CONVERGENCE ZONEDURING NORTHERN SUMMER - A GLOBAL PERSPECTIVE

D.K. Paul1, V.R. Deshpande1, V.R. Mujumdar1, S.P. Ghanekar1,
U.V. Bhide1 and T. C. Chen2

1Indian Institute of Tropical Meteorology, Pune-411008, India

2IOWA State University, Ames, IA 50011, USA


The tropical atmosphere shows a distinguishing feature of
lower tropospheric convergence in the northern hemisphere
occurring in the upward branch of the meridional Hadley circu-

lation located in the Intertropical Convergence Zone (ITCZ).
The east-west oriented ITCZ is the region of enhanced
convection and precipitation. The organisation of convection
over the planetary scale ITCZ are studied based on
contemporary data of global Outgoing Longwave Radiation (OLR)
for 1975-1990, precipitation (P) estimate derived from
satellite data at the Global Precipitation Climate Project
(GPCP) for 1986-1993 and Sea Surface Temperature (SST) of
COADS and TOGA. Surface meteorological data of ECMWF and upper
air data of NMC for few years are also utilsed in the study.
The ITCZ structure is delineated in the analysis of long term
mean OLR and P for the northern summer season (JJAS) as an
east-west oriented belt of low OLR values of a few degrees of
latitude in width with enhanced precipitation within the
belts. The longitudinal assymetry of the planetary scale ITCZ
is reflected from the regionally organised deep convection
over some preferential longitudinal belts. The most prominent
amongst these are that over the equatorial (a)
Indo-Pacific(IP), 70*E- 160*E , (b) Eastern Pacific-Central
American(EPCA), 120*W-60*W and the west African(WA), 20*W-30*E
belts. While the convective regions over these belts have a
latitudinal extent of about 10* (5*-15*N), the same over the
Indian longitudes (70*-95*E) is three times as large,
stretching from the near equatorial oceanic region towards
continental monsoon trough region. In this paper we studied
the intraseasonal fluctuation of convective episodes over
different regions and the phase relationship of their
oscillations during northern summer. A prominent out of phase
oscillation of large scale convective episodes in the ITCZ are
observed between the IP and EPCA regions. The contribution of
low frequency modes in the inphase/out of phase oscillations
of convective episodes between different regions are examined.
The transport of heat and moisture by planetary scale zonal
Walker cell which enhances the convective activity in the
region containing the convergent cell and suppresses the same
in the region that contains the divergent cells are studied
through global divergent circulation and divergent water vapor
transport. The interannual variability of the large scale
convective activity and precipitation over different regions
and their relationship with El-nino/La-nina events are also
examined.

DANSGAARD-OESCHGER OSCILLATIONS

W.R. Peltier and K. Sakai

Department of Physics, University of Toronto
60 St. George Street, Toronto, Ontario M5S 1A7, Canada

The most striking characteristic of the climate state that
prevailed during full glacial conditions, according to k180
isotopic data from the deep ice cores recently acquired from
Summit, Greenland sites (GRIP 1993a,b; GISP2 1993a,b), is the
prominence of millennium timescale Dansgaard-Oeschger
oscillations. These intense quasi-periodic fluctuations imply
periodic peak-to-peak temperature variations throughout the
North Atlantic sector on the order of 6F8C. Since the Greenland
ice sheet is proximate to the region of most intense NADW
formation in the modern climate system, and since this process
is clearly associated with significant rates of heat loss to
the atmosphere, it is not unreasonable on a-priori grounds to
suspect that D-O oscillations might be connected to variations
in the strength of the thermohaline circulation. However, no
dynamically credible model has yet been constructed that
satisfactorily demonstrates that this connection is physically
tenable. We have developed, and will describe, a new
multi-basin reduced model of the global thermohaline
circulation that has been designed specifically to investigate
the validity of this hypothesis of the origin of D-O timescale
variability. The model consists of separate longitudinally in-

tegrated meridionally oriented representations of the
Atlantic, Pacific and Indian Ocean basins linked through a
zonal circumpolar channel representative of the Southern
Ocean. When forced with T and P-E surface boundary conditions
appropriate to the modern climate, the model delivers weak
century timescale variability that is compatible with the
extremely stable climate regime that has been characteristic
of the entire Holocene epoch. However, when the surface
boundary conditions are adjusted to accord with CLIMAP
inferences of SST and with the inferences of Duplessy et al.
(1991) for surface salinity, for full glacial conditions, then
the internal variability of the model is completely
transformed. In the full glacial regime the model predicts the
occurrence of extremely large amplitude millennium timescale
quasi-periodic oscillations of the Dansgaard-Oeschger type.
The same model has also been employed to test the hypothesis
that the Younger-Dryas cool period, that interrupted the
general trend towards warmer conditions that was
characteristic of the last glacial-interglacial transition,
was induced by a shutdown of the thermohaline circulation
caused by the flooding of the North Atlantic by the glacial
meltwater episodes that have been inferred on the basis of the
relative sea level record at Barbados (Fairbanks, 1989). When
the model is forced with a realistic space-time history of
meltwater loading it delivers a synthetic Y-D event that
closely matches the observed. We will discuss the implications
of these analyses to the understanding of climate system
stability in general.

References

Duplessy, J.-C., L. Labeyrie, A. Juillet-Leclerc, F. Maitne,
J. Dupart, and M. Sarnthein, Surface salinity
reconstruction of the North Atlantic ocean during the
last glacial maximum, Oceanologica acta, 14, 311-323,
1991.
Fairbanks, R.G., A. 17,000-year glacio-eustatic sea level
record: influence of glacial melting rates on the
Younger-Dryas event and deep-ocean circulation. Nature,
342, 637-642, 1989..

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VENTILATION OF OCEAN THERMOCLINE BY SALT FINGERS CONVECTION
A. I. Pereskokov
All-Russian Research Institute of Hydrometeorological
Information-World Data Center, 6, Korolyov Str., 249020,
Obninsk, Russia

One of the most obvious and common tendencies in modern
physical oceanology is to study the effects of processes and
phenomena of the smaller scales on the processes and phenomena
of the larger scales. Using the global set of deep-water
observations for 1900-90 as original material, collected by
now at RIHMI-WDC Oceanographic Data Centre, a close
interaction is determined between the areas, favourable for
the development of salt fingers convection with the areas of
higher oxygen saturation of waters in the subtropical ocean
regions.
It is also shown, that the penetration of tritium into water
column after the first nuclear tests is also explained by
cumulative effect of salt fingers.
In some regions of the World Ocean, for example in the Black
sea, Norwegian fiords, Cariaco trench, where therohaline
background for acting the salt fingers is absent, even
anaerobic conditions are observed.
Hence, salt fingers convection, explained by the differences
in molecular heat and salt diffusion (by about 100 times),
plays a great role as a supplier of heat, salt dissolved
gases, biogenic elements and other components into the ocean
water depth.
Considering all the above-mentioned it becomes evident, that
the existence of different types of vertical stratification of
temperature and salinity is the most important peculiar
feature of the ocean, significantly differentiating the
character of the vertical exchange of energy and substances
and, hence, the conditions of flora and fauna existence.

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PALEOSOIL DATA AS A BASIS FOR PALEOCLIMATIC
RECONSTRUCTION FOR THE SECOND HALF AT
THE HOLOCENE IN PRIAZOV'E
L. Pesochina

Institute of Soil Science and Photosynthesis RAS
142292 Pushchino, Moscow region, Russia

Paleosoils buried under archaeological monuments (kurgans,
banks, necropolises and etc.) are the unique research
matherial reflecting paleoenvironmental conditions for periods
of its burial. Paleopedologists can examine soil
chronosequences comprising paleosoils, buried during the
second half of Holocene at intervals from 100 to 500 years due
to archaeological monuments widely extended all over the
forest-steppe and especially steppe zones of Russia. Dating of
the monuments and, consequently, time of soil buried can be
usually established in accordance with the archaeological
chronology up to 50-100 years for the Early Iron and the
Middle Ages and up to 200-300 years for the Bronze Age.
The emphasis in the present work is given to both theoretical
and practical aspects of the usage of paleosoils in
reconstructing of paleoenvironment for the second half of
Holocene in Priazov'e. The main theoretical problem is: what
soil diagnostic features should involve as the basis for
reconstructing of paleoclimatic conditions? We suggest to
select the number of elementary soil-forming processes which
are the most susceptible to hydrothermal changes of
paleoclimates and are characterized by minimum sufficient
complex of soil properties formed in each process. The object
under study was the soil chronosequence, comprising paleosoils
buried 4000, 3700, 2400, 1200 years ago and modern soils,
situated on the territory of Rostov region. The
morphological-chemical complex analyses were carried out by
methods usually used in pedology.

Considerable changes of soils for some Holocene chronocuts
were observed. Among all soil-forming processes effected on
soils of this chronosequence the 2 groups of processes such as
humus formation and the substance migration (salt migration:
salinization-desalinization;
solonetzization-desolonetzization; calcium migration:
leaching, gypsum and calcite accumulations) were the most
dynamic and were closely connected with climatic conditions.
Humus formation as indicator of climatic changes can be
estimated mainly by group and fraction humus composition. The
main soil characteristics of substance migration are average
contents and stores of easily-soluble salts, carbonates and
gypsum in different soil layers as well as the content of
exchangeable Na in soil-absorbing-complex combined with
morphological solonetzic properties.
It has been established that periods of the Bronze Age (about
4-3,7 thousand years ago) and of the Middle Ages (VIII century
A.D.) were characterized by climatic aridization caused soil
salinity while the climatic in the Early Iron Age (2400 years
ago) was cooler and specified by higher humidity the evidence
of which was absence of easily soluble salt and gypsum
accumulations, lack of actual solonetzic features and
decreasing of humus acid content.
This work was carried out under support of Russian Fundamental
Investigate Foundation.

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ATMOSPHERIC C13/C12 AND THE GLOBAL DISTRIBUTION
OF CARBON DIOXIDE SOURCES AND SINKS

S. Piper

Scripps Institution of Oceanography
La Jolla, California 92093-0220, USA

A three-dimensional atmospheric transport model with observed
winds is used to re-examine the global carbon budget for the
early 1980's. We have reconstructed the CO2 sources and sinks
described in the study of Tans, Fung and Takahashi (1990),
applied C13/C12 isotopic fractionation factors, and compared
CO2 and C13/C12 model predictions with the atmospheric
observations along a north-south transect of the measuring
stations of Keeling et al. (1989). Whereas these simulations
produce a good match with atmospheric CO2 observations, as
shown by Tans et al., they underestimate the north-south
atmospheric C13/C12 gradient of -0.18 per mil by about 0.10
per mil. Therefore, the C13/C12 simulations do not appear to
support the existence of a large 2 to 3 GtC per year northern
temperate biosphere sink as suggested by Tans et al. (1990),
but rather are consistent with a large northern ocean sink
described by Keeling, Piper and Heimann (1989).

Several simplifications were employed in these simulations:
fossil fuel was simulated as a single component with a
constant and uniform C13/C12 composition; a single uniform
fractionation factor was applied to the land biota flux (in
particular, plants with the C4 metabolic pathway were not
accounted for); the flux of CO2 from biomass burning was not
included; the flux of CO2 via carbon monoxide was not included;
CO2 in river runoff was not accounted for; and geographic
variation of the Suess Effect in the terrestrial biosphere was
not simulated. By using a carbon monoxide source from J.
Logan, we obtained a reduction to the northern nonfossil sinks
of less than 0.1 GtC per year, about one-third as large as
that found in a 2-D simulation by Enting and Mansbridge
(1992). In addition, we found that rivers (Sarmiento and
Sundquist, 1992) provide a CO2 flux that is largely localized
in the northern hemisphere, thereby providing a land-based CO2
sink with a more nearly "oceanic" C13/C12 signature that is
required to reconcile ocean dpCO2 observations with the
gradient in atmospheric C13/C12.

We will describe this and other work which attempts to remove
each of the simplifications above, for the global carbon
dioxide cycle in the early 1980's, briefly contrasting the
results with simulations for 1987-1988 and for the early
1990's.

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BIOGEOCHEMICAL CONSEQUENCES OF NON-UNIQUENESS OF OCEAN
THERMOHALINE CIRCULATION

E.E.Popova, B.A.Kagan and V.A.Ryabchenko

St.Petersburg Branch, Shirshov Institute of Oceanology
30, Pervaya Liniya, 199053 St.Petersburg, Russia

Specific features in the spatial distribution of
biogeochemical characteristics inherent in the most probable
stable equilibria of the ocean thermohaline circulation (OTHC)
are identified using a simple coupled
thermodynamical/biogeochemical model of a three-water mass
(surface, intermediate and deep) ventilated ocean. It is shown
that the most probable stable steady states of the OTHC are
only 6 of 16 stable steady states. The OTHC pattern in the
modern North Atlantic can be identified with that described by
the first or sixth most probable states. The first
characterizes the asymmetric circulation with the predominance
of the thermal mode in the Northern Hemisphere and of the
thermal and haline modes, respectively, in the
surface/intermediate and intermediate/deep water mass systems
of the Southern Hemisphere. The sixth state corresponds to the
symmetric circulation with the prevailing thermal modes in
both hemispheres. A comparison of nutrient distributions
corresponding to these two OTHC patterns with distributions
inherent in the other four most probable equilibria shows,
that none of these latter distributions can reproduce the
observed nutrient content changes (a depletion of the surface
and intermediate waters and an enrichment of the deep waters)
in the glacial North Atlantic. It follows that some
quantitative variations in the total transport between
neighbouring water masses are more likely than any radical
reorganization of the OTHC to be a reason of the observed
changes. It is also demonstrated that these latter could be
caused by a decrease in the total transport in the
intermediate/deep water mass system rather than by an increase
in the total transport in the surface/intermediate water mass
system.
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HISTORICAL VARIATIONS IN TERRESTRIAL
BIOSPHERIC CARBON STORAGE
W. M. Post, A. W. King, and S. D. Wullschleger,
Environmental Sciences Division, Oak Ridge National
Laboratory,Oak Ridge, TN 37831-6335, USA
Changes in carbon storage in terrestrial ecosystems are a
consequence of shifts in the balance between net primary
production (NPP) and heterotrophic respiration (R_H). Both NPP
and R_H are responsive to variations in climate. It is
possible that historical changes in regional and global
climate have altered terrestrial biospheric carbon storage.
Climatic variations which favored NPP over R_H would lead to
increased ecosystem carbon storage and could account for at
least part of the large terrestrial sink required to balance
the historical and contemporary global carbon budget.
To test this hypothesis, we employ a georeferenced global
terrestrial biosphere model of 0.5 degree spatial and monthly
temporal resolution. NPP is calculated as the difference
between gross primary production and plant respiration. Gross
primary production is modeled with a big-leaf model of canopy
photosynthesis responsive to changes in atmospheric CO2,
temperature, soil water, and soil nitrogen. Plant respiration
is modeled as a function of temperature and tissue nitrogen
content. Heterotrophic (i.e., decomposer) respiration is
simulated with a process submodel of litter and soil carbon
and nitrogen dynamics that responds to changes in temperature
and soil moisture. Changes in soil moisture are modeled as a
function of changes in precipitation and evapotranspiration
with transpiration calculated by the big-leaf canopy model.
The model is driven from an assumed equilibrium in 1935 using
gridded historical time series of monthly temperature and
precipitation and combined ice-core and monitoring station
records of changes in atmospheric CO2. We present maps of
changes in NPP, R_H, and ecosystem carbon storage for the
period 1935 to present and estimates of the terrestrial net
flux of carbon accounted for by changes in climate and
atmospheric CO2. We also present analyses of the relative
contribution of changes in climate and atmospheric CO2 to
changes in ecosystem carbon storage and of the relative
contribution of secular and interannual changes in climate.


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GLOBAL MONITORING OF PRIMARY PRODUCTION

Stephen D. Prince and Samuel N. Goward

Laboratory for Global Remote Sensing Studies, Geography
Department,
University of Maryland, College Park, MD 20742-8225, USA

A new model of global primary production, based on the
production efficiency concept, called the GLObal Production
Efficiency Model (GLO-PEM) is described. Although this is not
the first attempt to model global net primary production (NPP)
using the production efficiency approach, it is the first to
model gross primary production (GPP) and is unique in two
further, significant respects.
First, we drive the model almost entirely by satellite
measurements which give global, repetitive, spatially
contiguous, and time specific observations. Thus the
measurements are of the actual vegetation rather than a
theoretical, potential vegetation cover as in the case of most
NPP models that do not use satellite data. GLO-PEM, however,
goes beyond existing satellite vegetation index NPP models and
attempts to estimate not only vegetation indices using the
satellite observations but also the values of the climatic and
environmental factors that modulate potential production in
the production efficiency approach. The algorithms are based
on our experience in modeling NPP in several large field
experiments, however this is a first attempt at multiple
variable extraction from the satellite data for ecosystem
modeling at a global scale.
Secondly, GLO-PEM is mechanistic, being based entirely on
physiological principles. In particular the amount of carbon
fixed per unit absorbed photosynthetically active radiation
(EE) is modeled rather than fitted using field observations.
Existing production-efficiency NPP models depend on field
observations of e to calibrate the algorithms and are thus
subject to the problems of biased sampling and measurement
errors inherent in the calibration.
We have used the first year (1987) of the NOAA/NASA AVHRR Land
Pathfinder data set with 8 x 8 km resolution and global
coverage. Although the AVHRR is a rather simple multispectral
sensor, it provides a wealth of information relevant to
biospheric monitoring. There is an urgent need to prepare for
the new generation of satellite remote sensing systems that
are expected to come into operation shortly; the analytical
framework we have developed is, therefore, not specific to the
AVHRR sensor.


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VARIABLILITY OF THE THERMAL STRUCTURE IN THE TROPICAL EASTERN INDIAN AND ESTERN PACIFIC OCEANS IN A CLOBAL GCM

Tangdong Qu

Institut of Oceanology, Academia Sinica Quingdao 266071, China

The world's climate seems to be particularly sensitive to the variation of sea surface temperature (SST) in the tropical eastern Indian and western Pacific Oceans. There fore, understanding how the SST is changed in this important region is of high priority for climate prediction. Surface heat budget analyses are usually not possible with observatio ns alone, because not all the necessary data are ordinarily available. Using a high-resolutio n general circulation model (GCM, Semtner & Chervin, 1992) combined with existing observations, this study provides a comprehensive description of the variability of surface thermal structure and its forcing mechanisms in the region. Although the model results may not be especially realistic, they at least help explore how ocean dynamics and ocean-atmosphere exchange of heat determine the surface thermal structure.

Comparison with observations indicates that the Semtner-Chervin model does a surprisingly good job in reproducing the observed upper-layer thermal structure and circulation, which no doubt indreases our confidence in the quality of the model. It is shown that different mechanisms are balancing the surface heat budget in different parts of the region, with the region partitioned into several smaller areas. In the eastern Indian Ocean (5 - 20F8S, 105 -120F8E), the primary control on the seasonal variation of SST is the surface heat flux; but, about half of the flux is balanced by advection near the coast of north-Aus tralia. The remotely forced waves are not important in the surface heat budget because th e SST depressions are quite small near the coast of Indonesia compared to those in othe r eastern-boundary upwelling regions.

In the western Pacific Ocean (20F8S - 20F8N, western b oundary-160F8E), surface heat flux does not change very much throughout the year both near the equator (3F8S - 3F8N) and in the North Equatorial Countercurrent (NECC, 3F8N - 9F8N), and the surface heat content is controlled by advection which is dominated respectively by verti cal circulation near the equator and by horizontal and vertical circulation together in the NECC. As observed, the remotely forced annual baroclinic wave activities may significa ntly affect the surface thermal structure in the neighborhood of 6F8N. In the region of N orth Equatorial Current (9F8N - 20F8N), South Equatorial Current (3F8S - 11F8S), and So uth Equatorial Countercurrent (11F8S - 20F8S), in addition to ocean dynamics surface heat flux can also play a major role in the generation of SST anomalies.

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REGIONAL CARBON CYCLE MODEL FOR AFRICA

K.V.O. Rabah1 and B.H. Braswell2

1Department of Physics, University of Nairobi,
P.O. Box 30197, Nairobi, Kenya

2Nationale Center for Atmospheric Research,
PO Box 3000, Boulder, CO 8037, USA


see faxed text


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PAST TEMPERATURE VARIATIONS INFERRED FROM A k18O RECORD OF
TROPICAL PEATS IN SOUTHERN INDIA

G. Rajagopalan1, R. Sukumar1, R.Ramesh2, R.K.Pant2 and G.
Rajagopalan3

1Centre for Ecological Sciences, Indian Institute of Science
Bangalore - 560 012, INDIA

2Physical Research Laboratory, Navrangpura, Ahmedabad - 380 009,
INDIA
3Birbal Sahni Institute of Palaeobotany, Lucknow - 226 007, INDIA


Climate change and its consequences on ecosystems, both natural and
man-made, have become a serious concern in recent years. In
particular, the possibilities of global warming as a result of
rising levels of greenhouse gases such as CO2 in atmosphere has
important implications. Palaeoclimatic studies that look at natural
variability in climate become important in this context. We are
studying past climatic changes in the Nilgiri hills, southern India
using peat deposits in this region. The 18O/16O ratio in cellulose
is a reliable record of the stable isotope ratio of the leaf water
used by the plant during its growth (Epstein et al., 1977). Higher
rates of evapotranspiration (which is a function of ambient
temperature and relative humidity) enriches the leaf water in the
heavy isotope of oxygen (high k18O value) and thereby of cellulose.

We report here the preliminary results of k18O analyses on
cellulose extracted from peat deposits dating back to 40,000 years
BP. k18O values varied from 21 per mil to 30 per mil. Through a
study of seasonal k18O values in cellulose of modern plants at the
same location, we are also attempting to establish an empirical
relationship between the isotopic value and mean ambient
temperature. The 9 per mil variation in cellulose from peat is
indicative of an overall variation of 4.5 xC in mean temperature
during the past 40,000 yrs in this region. The oxygen isotopic
record in peats seems to have considerable potential in reflecting
past temperatures. This may also serve as an useful input for
models aimed at studying future climatic changes in the continental
tropics.

Reference: Epstein, S., Thompson, P., Yapp, C.J. Science,
198:1209-1215, (1977)


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.
DIURNAL VARIATION ON PHYTOPLANKTON PRIMARY PRODUCTIVITY
AND OTHER RELATED PARAMETERS AT THE ICE-EDGE OF ANTARCTICA

M.Jiyalal Ram

National Institute of Oceanography, Regional Centre,
Sea shell, Seven Bungalows, Andheri, Versova,
Bombay - 400 061, India
Diurnal variation studies conducted on phytoplankton, primary
productivity and physico-chemical parameters near the ice edge of
Antarctica (Lat 69F8 46' - 69F8 54') during Jan-Feb 1990, indicated
the influence of temperature on primary productivity.

Fairly high value of dissolved oxygen (11.6mg l-1) at the super
saturation level, associated with markedly high phytoplankton
population count (182.50x104 l-1 cells) in the surface water was
observed due to photosynthesis. Temperature varied from -1.8 to 1.5
F8C. Highest temperature observed during February lowered the
salinity from 34.4 to 33.1% due to the melting of ice. Though there
was no direct correlation of nutrients to phytoplankton population,
the constant high concentration of phosphate (0.50-3.25 E6 mol dm-3)
nitrate (8.25-18.24 E6 mol dm-3) and nitrite (0.46-1.80 E6 mol dm-3)
indicated regeneration of nutrients in the coastal ice-edge zone
which supported enhanced growth of phyotoplankton (9.87-192.34,
avg. 92.32 x 104 l-1 cells) resulting fairly high phytoplankton
pigment (chl.a 1.07-5.34, avg. 3.41 mg m-3), primary productivity
(0.50-3.97, avg. 2.47 mg C m-3 h-1) and Standing crop (71.7-357.8
avg. 228.7mg m-3).

Larger cell size of some dominant phytoplankton species recorded
during this study, like Fragilaria oceanica (Breaths 36-64E6),
Fragilaria islandica (Breaths 46-50E6), Coscinodiscus lineatus
(diameter 48-68 E6) and Nitzschia closterium (lengths (148-158E6) as
compared to the species observed in the tropical waters was the
clear indication of adaptation to the cold condition by these
species.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


GLOBAL SYSTEM ANALYSIS TECHNIQUES IN MODELLING CHEMICAL
SYSTEMS: A MONTE CARLO UNCERTAINTY AND SENSITIVITY ANALYSIS
OF THE ATMOSPHERIC DMS OXIDATION

M. Remdio1, A. Saltelli2, J. Hjorth2 and J. Wilson2
1 Environment Institute, Joint Research Center, TP 321, 21020 Ispra,
Italy

2 Environment Institute, Joint Research Center, 21020 Ispra, Italy

Modelling the DMS oxidation in the atmosphere is relevant to
climate change studies, because of the important contribution of
DMS emissions to formation of climatically active atmospheric
aerosol and in particular the hypothesized feedback mechanism
linking the biogenic sulphur cycle to the greenhouse effect.
Given the large uncertainties in the parameters governing DMS
oxidation, the sensitivity of the model and the estimation of those
uncertainties are key aspects for the understanding of the relevant
processes.

Monte Carlo based system analysis techniques can assist in the
analysis of complex chemical reactions systems. Model
identification under uncertainty is a task where Monte Carlo
Sensitivity Analysis can be applied. Through the coupling of the
chemical kinetics model with a set of statistical subroutines
allowing the model to be run in a Monte Carlo fashion, the
uncertainty in the model predictions and the relative importance of
each input parameter can be quantified.

There is no consensus on an established reaction scheme for the
homogeneous gas phase DMS oxidation. In previous studies we have
shown that systematic use of system analysis tools, such as
uncertainty and sensitivity analyses, can also assist in the
elucidation of reaction pathways, for the OH-initiated DMS
oxidation. In that context alternative reaction pathways (branches)
were compared with observation in the presence of uncertainty. A
correct quantification of the propagation of the input parameters
uncertainty on the model results is in fact crucial in the
discrimination among alternative reaction schemes. In this paper,
we extend the previous studies by considering the heterogeneous
oxidation of sulfur-containing compounds and updating the
homogeneous reaction scheme. The chemical kinetics model is coupled
'offline' with a general circulation model, allowing the global
modelling of the marine boundary layer DMS oxidation.

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MULTIRESOLUTION TERRAIN MODELLING FOR COUPLED SIMULATION
DATA INTEGRATION AND VISUALIZATION

Risch, J.S., and Rykiel, E.J.

Pacific Northwest Laboratory, Richland, WA 99352, USA

Interpretation of data associated with integrated Earth system
models is becoming increasingly difficult as greater numbers of
models are combined to form comprehensive simulations and as
individual models become more complex. The multiple spatial
resolutions of the data used and produced by these systems often
compound this difficulty. Visualization and user interface
technologies under development at the U.S. Department of Energy's
Pacific Northwest Laboratory are intended to facilitate the
analysis of data generated by coupled Earth systems models by
providing tools for interactively displaying and manipulating model
input and output data in a clear and intuitive fashion. Current
efforts are directed towards the development of a multiresolution
data visualization system capable of storing and concurrently
displaying a variety of Earth sciences data types at global to
local scales.

The core of our visualization approach is a global multiresolution
terrain modeling system. The system utilizes a hierarchical
geodesic tessellation of the geoid to index three-dimensional
terrain models developed at multiple spatial resolutions. Adjacent
terrain models are topologically linked in the data structure to
enable fast access to adjoining data. In addition, the system
supports the draping of arbitrarily located and oriented raster
data onto the elevation models at all resolutions, providing the
capability to incorporate a variety of other data types for
concurrent analysis with terrain information. Such data types
include gridded simulation data, satellite image data, and data
processed using raster-based Geographic Information Systems. The
raster-draped terrain models are navigable in real time, enabling
interactive exploration of interrelationships among simulation
data, measured data, and terrain morphology. Additionally, the data
can be reprojected into a variety of common map projections to
provide a synoptic view of whole-Earth model data while maintaining
the topological relationships among database elements.

The software is currently being tested as a visualization tool for
analyzing coupled regional ecosystems
dynamics/climatological/hydrological models of the U.S. Pacific
Northwest. Other potential uses include resource management,
decision support, and policy communications. Enhancements to the
system user interface will eventually provide the capability to
query elements of the display environment graphically, as well as
enable interactive modification of model parameters for performing
computational steering of in-progress simulations.

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FIRST RESULTS OF A CONTINENTAL BIOSPHERE MODEL COUPLED
TO THE LOUVAIN-LA-NEUVE 2-D CLIMATE MODEL

C. Roelandt and M.-F. Loutre

Institut d'Astronomie et de Gophysique G.Lemaitre
Universit Catholique de Louvain
2, Chemin du Cyclotron, B-1348 Louvain-la-Neuve, Belgium.

A continental biosphere model, based on the BIOME model
(Prentice, 1992) and DEMETER (Foley, 1994), has been developed
and coupled to the LLN 2-D climate model (Gallee et al.,
1991,1992).
The LLN 2D climate model is a two dimension
(latitude--altitude) sectorially averaged model which links
the atmosphere, the ocean mixed layer, the sea-ice, the
continents and the ice sheets. In each latitudinal belt, the
surface is divided into a maximum of seven oceanic or
continental types. The atmosphere interacts with the other
components of the climate system through vertical fluxes of mo
mentum, heat, and water vapour.
The biosphere model calculates the nature of the plant cover
and the carbon reservoirs. For that purpose it uses a sub-grid
scale aggregation method designed as an entropic compaction
method which analyses the plant functional type combinations
areas, on a latitude-longitude grid. This allows the model to
take into account the complexity of the surface, to focus on
the more sensible areas such as the coasts and mountainous
regions and to run the biosphere model only on homogeneous
areas. We will present the results of the validation of the
biosphere model with the present climate, the sensitivity
studies through variation of temperature and precipitation and
a simulation of the plant cover at a period close to the last
climatic optimum.
References:
Gallee, H. , J.P. van Ypersele, T. Fichefet, C. Tricot, and A.
Berger, RSimulation of the last glacial cycle by a coupled,
sectorially averaged climate-ice sheet model. 1. The climate
model.S, Journal of Geophysical Research, vol. 96, n!D 7, pp.
13139-13161, 1991.
Gallee, H. , J.P. van Ypersele, T. Fichefet, I. Marsiat, C.
Tricot, and A. Berger, RSimulation of the last glacial cycle
by a coupled, sectorially averaged climate-ice sheet model. 2.
Response to insolation and CO2 variationsS, Journal of
Geophysical Research, vol. 96, n!D7, pp. 13139-13161, 1991.
Prentice, I.C., W. Cramer, S.P. Harrison, R. Leemans, R.A.
Monserud and A.M. So lomon, RA global biome model based on
plant physiology and dominance, soil properties and climateS,
Journal of Biogeography, 19, pp. 117-134, 1992.
Foley, J.A., R Net primary productivity of the terrestrial
biosphere: The application of a global modelS, Journal of
Geophysical Research, vol. 99, n! D10, pp. 20773-20783, 1994.

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MODELING HYDROLOGIC CYCLE-VEGETATION INTERACTIONS IN AN
INTEGRATED ASSESSMENT FRAMEWORK

Rosenberg, J., Edmonds R. Moss, and H. Pitcher

Battelle, Pacific Northwest Laboratories
Washington, DC, 22024

Hydrologic cycle-vegetation interactions will be affected by
climate change and will feedback to modify or exacerbate
climatic change through effects on albedo, surface roughness
and carbon cycle. Agroecosystems, hydrologic systems, forests
and unmanaged ecosystems are being modeled in an integrated
assessment framework at the Pacific Northwest Laboratories.
The economic behavior of human societies also affects climate
through emissions of greenhouse gases and other radiatively
active substances and by altering land use as the demand for
water and the products of the land increases with growing
populations and affluence. Integrated assessment is a tool
used to study the inter-relationships among these and many
other factors, phenomena, causes and effects of climate
change.
Battelle's Global Change Assessment Model (GCAM) is one
approach to integrated assessment. Process models have been
adapted for simulation of climate change effects on agricul-

tural productivity, streamflow and ground water recharge and
ecosystem species dominance, productivity and provenance.
These models of natural systems are coupled to one another and
to models that simulate economic behavior and climate
dynamics. The construction of an integrated assessment model
requires the application of advanced techniques to insure
consistency, tractability and computational efficiency. The
first GCAM covering the continental US will be completed in
1995. The effort is being extended to all of North America and
global coverage is planned. The GCAM structure, its ecosystem
simulation models and preliminary results will be described.


>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

INTERCOMPARISON OF LARGE-SCALE PRECIPITATION DERIVED
FROM CONVENTIONALLY MEASURED DATA,
SATELLITE OBSERVATIONS AND NUMERICAL MODELS

B. Rudolf and U. Schneider
Global Precipitation Climatology Centre, Deutscher Wetter-

dienst
Postfach 100465, D-63004 Offenbach/Main, Germany)

The GEWEX Global Precipitation Climatology Project (GPCP) was
established in order to provide climate modellers with verifi-

cation data sets based on observations. The Global Precipita-

tion Climatology Centre (GPCC), a central element of the GPCP,
covers the functions collection, quality-control and spatial
analysis of raingauge measurements for the land-surface, as
well as the operational merging of these analyses and satel-

lite-based estimates. For the verification of climate models,
the assessment of the error range of the observational prod-

ucts is of high importance. First gridded data sets produced
by the GPCC are available with a different horizontal
resolution: global on a 2.5F8 grid by Internet (World Wide
Web), and terrestrial on a 1.0F8 grid on CD-ROM distributed by
GEWEX International Office.

Area-average precipitation can be estimated from different ob-

servation techniques, such as conventional raingauges, ground-
based radar, and satellite-born instruments. Since none of
these techniques solely provides precipitation data sets with
complete global coverage, data sets from the different sources
have to be combined to evaluate complete global products. Each
one of these data sets has its advantages and shortcomings.
Rain-gauge measurements at stations are direct, but are point-
data, are available for land-surface only, and the measure-

ments can be locally influenced. Underestimation is caused by
wind drift, wetting and evaporation losses (systematic measur-

ing errors). The accuracy of area-average precipitation
calculated from point-data strongly depends on the density and
spatial distribution of the station network. Oceanic surface-
based observations are available from ships only for the main
routes, usually roughly estimated from weather observations by
eye. Remote-sensing methods are indirect, but provide precip-

itation estimates with a good coverage also over the oceans.
Several satellite observations (IR from geostationary satel-

lites and polar-orbiting NOAA satellites, microwave [MSU and
SSM/I] from polar-orbiting satellites) provide data from which
precipitation can be estimated for the oceans and - with more
reservation - for the land-surface. The relative error of the
global observational product merged from raingauge and
satellite data varies over a wide range from a few percent up
to about 100% depending on the regional data base. Ground-
based precipitation radar is not yet available for many coun-

tries. Calibrated radar data from Japan and UK are used for
spot-like validation studies.

Intercomparison studies including results from numerical
weather prediction models have been carried out by the GPCC
based on the large-scale monthly products. Intercomparisons
for specific regions, selected by availability of observed
data, are realized by several international projects, such as
the WetNet Precipitation Intercomparison Project or the GPCP
Algorithm Intercomparison Program. The satellite results, de-

rived by different algorithms, are contaminated by different
methodical as well as by sampling errors. The ECMWF model
(operational version during the test years 1987-89) obviously
overestimates convective rainfall and has an extensive spin-
up. The comparison of climate model results still shows large
deviations between the different models as well as between
models and observations.


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AN ALTERNATIVE WAY TO MODEL EFFICIENCY OF CARBON UPTAKE
BY TERRESTRIAL VEGETATION

A. Ruimy1, C. B. Field1, D. D. Baldocchi2

1Carnegie Institution of Washington, Department of Plant
Biology
290 Panama Street, Stanford, CA 94305, USA

2NOAA/ERL, Atmospheric Turbulence and Diffusion Division
456 South Illinois Avenue, P.O. box 2456, Oak Ridge, TN 37831,
USA

Parameteric type models postulate that terrestrial net primary
production (NPP) or gross primary production (GPP) can be
decomposed into incident solar radiation, absorption
efficiency of solar radiation, and conversion efficiency of
absorbed solar radiation into dry matter (for NPP) or
photosynthetic efficiency (for GPP). Conversion efficiency and
photosynthetic efficieny can be decomposed into optimal
efficiency and stress reduction factors. Absorption efficiency
can be derived relatively accurately from remote sensing data
such as AVHRR vegetation indices, but there is great
uncertainty about the value of the conversion efficiency, and
the effect that environmental factors such as water and
nutrient stresses, temperature, and vapor pressure deficit
have upon it.
Three different apporaches to parameterize conversion
efficiency or photosynthetic efficiency can be found in the
literature. The first approach is through calibration, i.e.
efficiency is fitted using linear regression and databases on
annual production and climate data, as in the
Carnegie-Ames-Stanford Approach (CASA). The second approach is
to use complex local production models with a high number of
parameters derived from field measurements, to derive
integrating parameters such as conversion efficiency that can
be used at the global scale, like in the BIOME-BioGeoChemical
cycles (BIOME-BGC) approach. The third approach is to
parameterize efficiencies directly from measurements, but few
tools are available to estimate efficiencies of whole canopy
production, at large time and space scales. Long term CO2 flux
measurements could be potentially helpful in this respect. In
the approach used by TURC (Terrestrial Uptake and Release of
Carbon), the mean response curve of CO2 fluxes measured over
plant canopies to solar radiation, in different environmental
conditions, with a variety of techniques, has been used to
parameterize mean photosynthetic efficiency.
This study links the TURC and CASA approaches. The variability
around the mean response curve of CO2 flux to solar radiation
used in TURC is analyzed in light of the variability of
environmental factors. This analysis is used to parameterize
the optimal photosynthetic efficiency and stress reduction
factors used in CASA. The resulting, unconstrained terrestrial
production estimates can be tested against the database used
to calibrate the original CASA approach.

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SIMULATING SURFACE CHLOROPHYLL DISTRIBUTION IN THE INDIAN
OCEAN AS A VALIDATION OF A 3-D
BIOGEOCHEMICAL-HYDRODYNAMIC MODEL

V.A.Ryabchenko1 , M.J.R.Fasham2 and V.A.Gorchakov1

1St.Petersburg Branch, Shirshov Institute of Oceanology
30, Pervaya Liniya, 199053 St.Petersburg, Russia

2James Rennell Centre for Ocean Circulation
Gamma House, Chilworth Research Centre, Southampton SO1 7NS,
U.K.

A nitrogen-based, seven-component ecosystem model of Fasham's
(1993) type is coupled to a climatological 3-D
quasi-geostrophic ocean general circulation model (OGCM) with
an integrated model of the upper mixed layer. The ecosystem
model, with a constant parameter set, simulates both the
high-chlorophyll/low-nitrate annual cycle observed in the
North Atlantic and the low-chlorophyll/high-nitrate cycle seen
in the North Pacific, so that it can be considered as a
globally robust model of the marine ecosystem. In the OGCM,
internal waves are filtered out allowing a large time step to
be used for the integration, so that long time integrations
are possible using less computer time than in conventional
OGCMs. To validate the coupled model before applying it to
modelling of the present-day state of the biogeochemical
cycles in the world ocean, it has been used for simulation of
the seasonal variability of both physical and ecosystem
variables in the Northern Indian Ocean, i.e. in the part of
the world ocean where seasonal changes have a maximum. The
model has been integrated for 100 years, and an equilibrium
solution for the upper ocean has been obtained. A comparison
of the simulated mean monthly surface chlorophyll
distributions with the CZCS ocean colour data shows good
qualitative agreement throughout the year, except during May.
This discrepancy may be connected with prescribing
climatological wind fields that can differ from those during a
period when the CZCS data were obtained. The good quality of
simulation of observations in the region of maximal seasonal
changes supports the idea that the model developed is a good
candidate to be an efficient oceanic component in global
biogeochemical models of atmosphere-land-ocean system.


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CARBON DIOXIDE AND CLIMATE AS A COUPLED DYNAMICAL SYSTEM

B. Saltzman

Department of Geology and Geophysics, Yale University,
P.O. Box 208109, New Haven, CT 06520-8109, USA

An analysis is made of the changes of CO2 implied by the Vostok
core measurements in relation to concomitant changes in global
ice volume and the state of the ocean, with emphasis on the
last 20,000 years. It is suggested that an explanation of
these changes requires the simultaneous consideration of all
these variables, in concert with the implied surface tempera-

ture changes, as coupled components of a dynamical system.
Since there are many physical and biogeochemical sources of
positive feedback in the global carbon cycle on this time
scale, the possibility exists that the system can become
unstable thereby allowing internal oscillatory behavior. Under
the "pacemaker" influence of orbital forcing such an
oscillation can account not only for the observed CO2
variations but also for changes in global ice, ocean state,
and surface temperature.The potential consequences of
anthropogenic CO2 forcing on this
dynamical behavior is discussed.

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The Search for A Model-Predicted Temperature-Change Signal in Observed Records of Temperature Change

B.D. Santer, K.E. Taylor, T.M.L. Wigley,
P.D. Jones, D.J. Karoly, J.F.B. Mitchell,
J.E. Penner, V. Ramaswamy, D. Schwarzkopf,
R.J. Stouffer and S.F.B. Tett

Several recent studies have compared observed changes in near-surface temperature with patterns of temperature change predicted by climate models in response to combined forcing by carbon dioxide and anthropogenic sulfate aerosols. This research (reviewed briefly here) suggests that a combined CO2 + anthropogenic sulfate aerosol signal is easier to identify in the observations than a pattern of temperature change due to CO2 alone. Here we extend this work to a comparison of modelled and observed patterns of vertical temperature change in the atmosphere. Results show that the observed and model-predicted changes in the mid- to low troposphere are in better accord with greenhouse warming predictions when the likely effects of anthropogenic sulfate aerosols and stratospheric ozone reduction are incorporated in model calculations. This improved correspondence is primarily due to hemispheric-scale temperature contrasts (reduced warming in the Northern Hemisphere). If current model-based estimates of natural internal variability are realistic, it is unlikely that the level of time-increasing similarity between modelled and predicted patterns of vertical temperature change could be due to natural internal fluctuations of the climate system. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Jorge L. Sarmiento The relative roles of CO2 solubility, biology, and anthropogenic carbon in determining the oceanic carbon distribution We use a global model of the ocean carbon cycle to examine the relative contribution of the solubility and biological pumps and anthropogenic CO2 invasion to the magnitude and spatial distribution of CO2 fluxes between the atmosphere and ocean. The global pre-industrial flux to the atmosphere from the tropics (15ÁS to 15ÁN) is 1.2 Pg C yr^-1 (1 Pg 1 Gt 10^15 g) made up of a solubility pump degassing flux of 1.4 Pg C yr^-1 and a biological pump uptake flux of 0.2 Pg C yr^-1. This is balanced by equal uptakes of 0.6 Pg C yr^-1 in both hemispheres. The northern hemisphere uptake is due almost entirely to the solubility pump. The southern hemisphere uptake is due to a solubility pump flux of 0.8 Pg C yr^-1 combined with a biological pump degassing flux of 0.2 Pg C yr^-1. Most of the southern hemisphere uptake occurs south of 30ÁS, where the total uptake of 0.5 Pg C yr^-1 consists of a solubility pump flux of 1.0 Pg C yr^-1 combined with a biological pump degassing flux of 0.5 Pg C yr^-1. Results of a simulation of the anthropogenic transient confirm that the biological pump has almost no impact on the magnitude or spatial distribution of oceanic uptake of anthropogenic carbon from the atmosphere. Simulations that include both the biological and solubility pumps take up 4.9% less anthropogenic carbon than those that have only the solubility pump. An Atlantic Ocean carbon budget developed from analysis of the model in combination with observations suggests that the air-sea flux of carbon is inadequate to supply the postulated large dissolved inorganic carbon export from the Atlantic. Other sources of carbon are required, such as an input from the Pacific via the Bering Strait and Arctic, river inflow, or an import of dissolved organic carbon. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


REGIONAL TELECONNECTIONS OF RAINFALL
WITH ENSO - A CASE STUDY FOR
CHHATTISGARH REGION OF CENTRAL INDIA

A.S.R.A.S. Sastri and A.K. Srivastava

Indira Gandhi Krishi Vishawavidyalaya
Raipur (M.P.) - 492 012 India

It is evident that ENSO events are responsible for floods in
some parts and droughts in the other. It is also established
that there are close linkages betweeen the space-time patterns
of global climate and natural resources and extreme climate
anomalies have therefore been associated with the degradation
of natural resources.
One of the major systems which has been linked to extreme
anomalies in climate at global, regional and local levels is
ENSO. The negative impacts of ENSO events have ranged from a
decrease in agricultural productions, water resources etc.
have led to severe drought conditions. Such regional anomalies
due to ENSO are reports by many (Ogallo, 1994, Folland et al
1986, Nicholson and Entekhabi, 1986).

In the Chhattisgarh region of Central India, with an average
annual rainfall of 1400 mm, rice is grown in about 3.7 million
hectares mostly under rainfed conditions during SW monsoon
(June - October) season. The average seasonal rainfall is
about 1200 mm, which is hardly sufficient to raise rice crop
without water stress under traditional cultivation practices.
Any negative deviation from the seasonal rainfall results in
decreased productivity of not only rice but also for other
crops too. Incidentally, the average productivity of rice in
this area is very low (only 1.0 to 1.2 tons/hectare).

It is observed that ENSO events result in drought conditions
in this area. The worst example is the 1988 ENSO had been
resulted into a severe drought of the century in this part and
productivity of all crops has drastically been reduced. In
this paper an attempt has been made to examine the regional
teleconnections of rainfall at different districts with ENSO
events during this century. The regional variability of the
impact of ENSO was examined in relation to the terrain,
topography, forest cover etc..

REFERENCES

Folland, C. K., T. N. Palmer and D.E. Parker, 1985: Sahel
rainfall and world-wide sea temperature, 1901-1985, Nature
320, pp 603-609.

Nicholson, S.E. and D. Entekhabi, 1986: The quasi-periodic
behaviour of rainfall variability in Africa and its
relationship to Southern Osciallation. Arch Met. Geophy Bio
Sci. A34, pp 322-348.

Ogallo, L.A., 1994: Validity of the ENSO-related impacts in
Eastern and Southern Africa. Workshop report on: "Usable
Science - Food Security, Early Warning and el Nino", 25-28
October 1993, Budapest, Hungary.


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THE PHOSPHORUS IN RIVER RUNOFF

V.S.Savenko, K.K.Edelstein, E.A.Zakharova
Moscow State University, Russia

The river runoff is one of the major element of biogeochemical
cycle of phosphorus in environment. We revised the data on
mineral and total dissolved P content in surface waters of 185
small catchment (with area of less than 50 sq.km) and 182
mediate and large rivers of the world. The concentration of
mineral as well as total dissolved phosphorus are governed by
lognormal distribution law. The average mediate concentrations
of mineral and dissolved phosphorus in surface waters is equal
to 7 and 28 ppb P for forest catchment; 117 and 250 ppb for
catchment with intensive agricaltural land use, 48 and 90 ppb
for land with 50% using for agricaltural goals, and 700 and
1500 ppb P for urban catchment. Mean-veight concentration of
mineral and total dissolved phosphorus in world-wide river
runoff is about of 38 and 108 ppb. The modern input of these
forms of phosphorus in the ocean is 1.48 and 4.15 million ton
P per year

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Nutrient regulation of the carbon cycle

DS Schimel, BH Braswell and B Moore III

Several recent studies have shown the importance of the nitrogen cycle in controling the dynamics of the carbon cycle. The sensitivity of ecosystem carbon storage to temperature change is modulated by nitrogen. This occurs because soil nitrogen is released when soil organic matter is oxidized by higher temperatures, allowing enhanced growth of nitrogen-limited ecosystems, particularly forests. We have recently shown that nutrient and water limitation of productivity become correlated as ecosystems approach steady-state.

This occurs because precipitation controls both nitrogen inputs and losses and as precipitation increases, nitrogen flux through ecosystems increases. Higher precipitation also allows more productivity and biomass accumulation, permiting more of the N flux to be captured in biomass and subsequently, soil carbon. As N retention increases, N availability tends to increase, leading to a correlation of precipitation, nutrient availability and productivity. When a system is forced from steady state, the carbon-nitrogen-water linkages induce a series of feedbacks influenced by the decadal time-scales of nutrient turnover in organic matter. The consequences of these interactions for the short and longterm responses of ecosystems to climate anomalies and change are significant. We will discuss nutrient interactions in relationship to several recent observed phenomena in the carbon system.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Dan Seidov

Glacial to interglacial changes of the circulation of the North Atlantic
ocean are examined using an intermediate 3-D ocean circulation model and
different scenarios for the ocean surface climatology.The circulation is
driven by the wind stress extracted from the T42 atmospheric model runs
performed by Max Plank Institute modelling group in Hamburg.The Holocene,
the Last Glacial Maximum (LGM), and the Melt Water Event near 13,500 yr BP
(MWE) sea surface thermohaline fields, to which the temperature and salinty
of the uppermost model layer relax, are specified. The effective sea surface
temperature (SST) and salinity (SSS) are assembled using CLIMAP (1981) SST
reconstructions, SSS reconstructions done by Duplessy et al. (1991), and
the reconstruction done for the north-eastern North-Atlantic (Sarnthein
et al., 1994; Seidov et al., 1995). Sensitivity to changes in wind
stress, effective SST and SSS gradients and to several model parameters
confirmed prime importance of the sea-ice cover in the northern North
Atlantic and freshwater fluxes in high-latitudes for diagnoses of long-term
ocean climate changes. Major glacial to interglacial changes happened in
the north-eastern part of the North Atlantic. The most important new feature
is the completely reversed glacial thermohaline conveyor in the subtropical
to subpolar latitudes. The convection sites during the LGM and MWE were
shifted almost to 40 deg N, and the North Atlantic Drift was practically
zonal, encountering the Western Europe coast instead of penetrating into the
Norwegian-Greenland Seas. NADW production was lessened in the LGM and
completely switched off during the MWE time slice. The MWE mode of
circulation in the northern North Atlantic was essentially different from
the Holocene and the LGM modes, both in the upper and deep ocean. The
transitions between the modes happened rather fast and can be characterized
as jumps. These sharp jumps from the modern to the glacial and to the
meltwater modes, could be the key to better understanding of the severe
ocean climate changes during last 18,000 years.
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------------------------------------------------------------
THE CHANGING CHEMICAL COMPOSITION OF THE ATMOSPHERE
Wolfgang Seiler and Juergen Hahn
Fraunhofer-Institut fuer Atmospaehrische Umweltforschung
Garmisch-Partenkirchen, Germany

The chemical composition of the atmosphere has changed significantly since pre-industrial times causing severe global and regional environmental problems, e.g. the depletion of stratospheric ozone or climate change. Long-term observations started in 1957 with the measurements of atmospheric CO2 at Mauna Loa, Hawaii. In later years, continuous and discontinuous measurements of atmospheric CO, N2O, CH4, various CFCs, and ozone were begun by various groups all over the globe. For short-lived trace gases such as NOx or thenumerous VOCs, continuous records are available only for recent years and a relatively small number of stations so that their temporal trends in large parts of the world are only poorly known or not known at all. CO2, N2O, most of the CFCs and CH4 are long-lived atmospheric trace gases with mean tropospheric residence times on the order of years. In contrast, the CO and ozone have residence times on the order of months in the free troposphere. The longer-lived the trace gases are, the more evenly are they distributed in the global troposphere, but even CO2 and CH4 exhibit distinct annual variations and small interhemispheric differencesin their troposheric abundance. These gases remain stable for a long time in the small air bubbles contained in glacier ice. Ice samples, more than 160,000 years old, have beenanalyzed so that the atmospheric abundance of these gases can be traced back to times long before the beginning of industrialization.

Available data shows that, since the beginning of industrialization and large-scale agriculture in the second half of the nineteenth century, the abundance of atmospheric CO2 and anumber of other atmospheric trace gases has been increasing exponentially with time. The growth rate for tropospheric CH4 appears to be slowing down with time since the early eighties. The reason for this temporal behaviour is still not clear. In the case of CFC-11 and CFC-12, the emission reductions according to the Montreal Protocol and its later amendmentsbegin to show an effect on the tropospheric abundance of these two halocarbons such thattheir growth rates decreased significantly during the last two to three years.

While CO obviously increased after World War II in the northern free troposphere for a number of years, a decreasing trend has been observed since the late eighties. In contrast, thet ropospheric CO in the southern hemisphere does not show any significant temporal trend.

Ozone in ground level air has increased over West Europe since the end of t he last century.The same appears to be true for free tropospheric ozone in the mid-latitude s of the northernhemisphere. The concentration of ozone in tropospheric air observed on the summit of the Zugspitze in Bavaria, Germany, had been increasing since the late seventies but remained constant during the last ten years. In the southern hemisphere, a long-term temporal trend of tropospheric ozone has not been observed.

The observed increases in the atmospheric abundance of the trace gases ment ioned are mainly due to increasing fossil fuel combustion, extending agricultural activities including large-scale deforestation in tropical and subtropical areas, and various in dustrial processes.The impact of these activities/processes on the budget of relevant atmosphe ric traceconstituents will be discussed.

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. GLOBAL MODELING OF SHORT- TO MID-TERM RESPONSES OF
THE TERRESTRIAL BIOSPHERE TO INCREASING ATMOSPHERIC CO2
P. J. Sellers1, L. Bounoua1, G. J. Collatz1, D. A. Randall2,
D. Dazlich2, S. Los3, J. Berry4, I. Fung5, J. Tucker1, C. Field4
11923, NASA/GSFC, Greenbelt, MD 20771
2Dept. of Atmospheric Sciences, Colorado State University,
Fort Collins, CO 80523
3Dept. of Geography, University of Maryland,
College Park, MD 20742
4Carnegie Institution,
Stanford, CA 94305

5School of Earth and Ocean Sciences, University of Victoria,
Victoria, British Columbia, Canada V8W 2Y2

A strategy is outlined for modeling the near-term (years to a
few decades) response of the terrestrial biosphere to
increasing atmospheric CO2 and the likely associated changes in
the physical climate systems. (i) A model of the
ecophysiological function of the land biosphere (SiB2) has
been formulated to calculate the surface atmosphere fluxes of
radiative energy, sensible and latent heat, momentum and CO2.
The model is forced by a directly-coupled general circulation
model of the atmosphere with surface boundary conditions
prescribed from satellite data (vegetation index) among other
sources. (ii) Components of the biosphere model and the
procedures for evaluating the satellite data prescriptions are
tested using data from large-scale field experiments. (iii)
The effects of spatial variability in vegetation cover, soil
moisture and topography are explicitly examined. The model has
been run to explore the relative importance of physiological
and radiative feedbacks on changes in the mid-continental
climates under 2 x CO2 conditions.

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REMOTE SENSING BASED SIMULATION MODELS FOR EVALUATING
HYDROLOGIC VARIABILITIES ON RICE PRODUCTION

M. Selvarajan, V. Jayaraman and M. G. Chandrasekhar

National Natural Resource Management Systems Indian Space
Research Organisation, New BEL Road, Bangalore, 560094 , INDIA

Rice production, source of food for the millions in the
tropical region, mostly depends on water availability in a
region during the growth period. Erratic monsoons, unstable
irrigation, and manifold increase of rice grown areas during
the past few decades have become matters of great concern in
the context of climate change, particularly with reference to
the Water Cycle. On the other hand, the rice hydrology is also
considered important, due to its influence on the micro
climate as near flooded conditions prevail in the fields
during the growing season, which govern emission of methane
and other trace gases. Further, the evapotranspiration from
the rice fields is also closely linked to the stomatal opening
and hence, to the CO2 release to the atmosphere.

While significant developments have taken place in computer
based simulation of the regional hydrologic systems and the
agro ecosystems, their operational use is often limited by the
inadequate data on the variability of soil-crop systems over
spatial and temporal scales. Generation of water dependent
rice production scenarios over regional scales require updated
data bases on the crop/soil/weather complex, as inputs to
regional hydrology and crop simulation models. In this paper
an approach is presented to combine satellite remote sensing
inputs on crop acreage, physiography, drainage pattern and
hydrogeologic boundary conditions with hydrologic and crop
simulation models, through simulation interfaces on spatial
variability. Based on this approach, regional water balance
models of typical rice systems of India were linked to the
crop models for generation of rice production scenario for
different water regimes such as low land, upland and irrigated
conditions. This procedure was eveluated for several
combinations of variations in soil, crop genotype and weather
conditions. Observed state variables on water balance and rice
growth were compared to simulated behavior as part of
sensitivity analysis. Based on this, different environmental
management options were evaluated for anticipated hydrologic
condtions in rice systems.

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MODELLING OF PRIMARY PRODUCTIVITY IN ARABIAN SEA

M.K.Sharada and K.S.Yajnik

Centre for Mathematical Modelling and Computer Simulation,
N.A.L., Belur Campus, Bangalore - 560037, INDIA

Marine biota play an important role in the global carbon
cycle. Ocean-ccarbon cycle models coupled with
ocean-atmosphere general circulation models can describe the
long-term response of ocean system to global change scenarios.
As a first step towards the development of such coupled, basin
scale models of ocean circulation and biogeochemical cycles,
we have been studying a class of dynamical models of marine
ecosystem for tropical conditions at selected stations in the
Arabian Sea. It is well known that Arabian Sea experiences
extremes in atmospheric forcing, which results in greatest
seasonal variability observed in any ocean basin. The link
between the physical forcing and the supply of organic matter
to deep waters is the planktonic food web, which has special
features here and merits investigation.
The central problem in modelling the primary production is to
model the interaction between the various components of the
ecosystem with climatological factors like solar radiation,
mixed layer depth, nutrients, upwelling etc. We have used a
nonlinear 7-component model of the marine ecosystem proposed
by Fasham et al(1990) to estimate the primary production in
Arabian Sea. Simulations were carried out for the mixed layer
for climatologi- -cal variation of solar radiation, mixed
layer depth and upwelling velocity to study the sensitivity to
selected parameters. Two parameters affecting the nutrient
supply, namely, subsurface nitrate concentration and diffusion
parameter, were varied. In addition, three ecosystem
parameters, namely, asymptotic grazing rate of zooplankton,
grazing preference of zooplankton and detritus sinking rate
were also varied. Simulations were carried out for 4 and 6
years which clearly indicate that the averages in the fourth
year are to a very good approximation equal to those in the
sixth year. We have therefore used the fourth year averages to
determine annual averages.
Annual averages of all components as well as fluxes have been
obtained to give a quantitative picture of sensitivity of the
ecosystem from the cabon-flux point of view to various
parameters. The system is found to be most sensitive to
asymptotic grazing rate and subsurface nitrate concentration.
It is also found that variation of chlorophyll with subsurface
nitrate concentration is nonlinear. The following table shows
the annual averages of new production at six stations in
Arabian Sea for two values of asymptotic grazing rate of
zooplankton,g. Stations A to D are on a transect normal to the
coast of Oman close to proposed long stations of US-JGOFS and
the stations E and F are also close to US-JGOFS and Indian
JGOFS transects. It is seen from the table that doubling of
the asymptotic grazing rate results in the decrease of new
production by 20-40%. NEW PRODUCTION

STATION
g 3D 1
g 3D 2


A 18 N, 58 E
10,8
6,7


B 17 N, 60 E
10,6
6,8


C 16 N, 62 E
7,4
5,8


D 14.5 N, 65
E
5,5
4,8


E 10 N, 65 E
4,8
3,9


F 19 N, 67 E
7,4
5,1

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USAGE OF RELIEF DISSECTION DATA FOR REGIONAL
HYDROCLIMATOLOGICAL CALCULATIONS AND CLIMATE MODELING

A.B.Shmakin, S.A.Bulanov

Institute of Geography, Russian Academy of Sciences,
Staromonetny St., 29,
Moscow 109017, Russia Fax: (7-095) 230-2090. E-mail:
climat@glas.apc.org

The land relief plays rather important role in the climate
system. While the absolute and relative height, as well as
steepness and aspect of the slopes are considered in the
climate studies already, the relief dissection itself was out
of attention usually. Nevertheless, it is dissection that
determines many aspects of land-atmosphere interactions:
surface aerodynamic roughness; secondary reflection and
emission of radiation fluxes; runoff formation and soil water
regime. In order to use the morphometric information in the
hydroclimatological studies, one have to reproduce the
dissection quantitatively. Namely, it is necessary to choose a
set of parameters which could describe the dissection
completely and give one an opportunity to take it into account
in the calculations of climatic parameters.

The scales of the modeled hydroclimatic processes must be
taken into account for the choice of the kind of
morphometrical information needed for the calculations. In the
given study, the main attention was paid to the
land-atmosphere energy/water exchange of regional scales (of
the order of 100-1000 km), while in some cases these processes
are connected with local-scale and mesoscale ones. For
example, the river runoff formation and secondary radiation
transfer between slopes are strongly influenced by the
dissection in the scale of elementary valleys. For such
spatial scales, a conventional image of relief of elementary
valleys was introduced. Three necessary parameters of relief
dissection are enough for the complete description of its
configuration: the fraction of flat water divides per unit
length profile; the total length of valleys per unit area; the
deepness of elementary valleys. The data base of these
parameters was created for the main part of Eurasia using the
topographical maps. The dissection parameters were averaged
over the study territory for grid cells of 1x1 degree
according to the scale of modeled processes.

For the calculations of some hydroclimatological parameters, a
parameterization scheme was used. It provides the temporal
coarse of all main heat/water balance components according to
the forcing parameters (weather conditions) and land cover
features. After the realization of the scheme, one can obtain
some information about the regional heat/water exchange at the
given territory in accordance with the spatial distribution of
dissection parameters. For example, it was obtained that the
role of feedback between river runoff and climate (i.e. the
replenishment of soil water storage by water coming from
outside with rivers) becomes much larger in the territories
where strongly dissected highlands and non-dissected lowlands
are adjacent to each other.

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THE IMPORTANCE OF STRUCTURE IN UNDERSTANDING GLOBAL CHANGE

H. H. Shugart and W. R. Emanuel

Department of Environmental Sciences
University of Virginia
Charlottesville, Virginia 22901, USA

The structure of the terrestrial vegetation and, in
particular, its dynamics, can have a profound effect on the
functional responses of terrestrial surfaces. These include
the response of the terrestrial surface to environmental
change, and on feedback interactions with other major earth
systems, notably interactions with the atmosphere. The static
structure of the vegetation alters the manner in which
fundamental processes such as photosynthesis "scale-up" in
space. For example, leaf responses to water, light, radiation
fluxes and CO2 concentration scale-up to canopy and landscape
processes in non-linear fashions that are highly dependent on
the structure of the vegetation. This strong scale-mediated
structure-to-process interaction has been a major challenge to
plant physiologists wishing to understand the implications of
leaf and tissue level responses of plants at landscape and
larger levels for at least the past 3 decades.

Dynamic responses of vegetation structure, ranging from
changes in leaf area profiles with birth-death processes, to
successional changes in plant life forms, to migration rates
of vegetation types and biomes, can have profound effects on
the functional responses of the terrestrial surfaces. Many of
these responses have the effect of adding inertia or time lags
to the terrestrial surface response. While this inertia may
reduce the fast responsivity of the terrestrial surface to
change, the lag effects can also produce more complex
interactions in conjunction with feedbacks to other major
earth systems. An example that will be discussed is the
varying degrees of inertia in terrestrial processes in
response to change. In the case of a unit change in climate,
these differences in flunctional response (in many many cases
due to the restructuring of ecosystems in response to change)
can potentially produce an overshoot in the carbon source to
the atmosphere of significant consequence.

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ENHANCED UV-B EFFECTS ON PHOTOSYNTHESIS AND BIOPRODUCTIVITY
OF THREE CULTIVARS OF WHEAT (Triticum aestivum)

R. Shyam, R. Chaturvedi and P.V. Sane,
National Botanical Research Institute
Lucknow 226 001, INDIA

Enhanced UV-B effects on the photosynthesis, shoot biomass and
grain yield of three cultivars of wheat cvs. RR-21, HD 2189
and HD 2285 were studied on field grown plants. Cultivars were
exposed from 25 to 100% increase in UV-B over the ambient from
seedling to maturity of grain stage. Enhanced UV-B was
provided by UVB-313 lamps. Appropriate filters i.e. cellulose
acetate and polyester film were used to cut UV-C and to
provide equal amount of UV-A emitted by lamps in both control
and treatment plots. Plant growth analysis, photosynthesis
(gas exchange measurement, electron transport reactions and
RuBP carboxylase activity), pigments (chlorophylls,
carotenoids, anthocyanins and flavonoids), proteins (SDS-PAGE
analysis of total soluble leaf proteins and thylakoid membrane
proteins), shoot biomas, tillers per plant and grain yield
were the parameters which were routinely assayed during the
life cycle of plant to evaluate the enhanced UV-B effects for
two successive years.

A gradual decline in the activity of most of the parameters
was recorded in all the three cultivars exposed to UV-B. The
maximum decrease in net photosynthesis, RuBP carboxylase
activity and partial electron transport reaction of PSII was
determined to be 40-60% 21-40% and 22-40% respectively. Of the
three cultivars HD 2189 was found to be more sensitive than RR
21 and HD 2285. Both photosynthetic (chl a, b and carotenoids)
and non-photosynthetic (anthocyanins and flavonoids) pigments
showed an increase in UV-B treated plants. HD 2285, however,
showed a pronounced increase in carotenoids and flavonoids as
compared to RR 21 and HD 2189. SDS-PAGE analysis of total
soluble leaf proteins and thylakoid membrane proteins
indicated some quantitative and qualitative differences with
reference to few of the polypeptide bands in the samples of
treated plants. A clear indication of decrease in larger (55
kDa) and smaller (14 kDa) subunits of RuBP carboxylase was
noticed in all the three cultivars of wheat.

While plant height and number of tillers per plant were
unaffected by UV-B, the grain yield showed a decrease as
compared to shoot biomass in treated cultivars. HD 2189 showed
a maximum reduction in both shoot biomass (20%) and grain
yield (26%). RR 21 was less affected as compared to HD 2189
and HD 2285 was found to be marginally affected with respect
to shoot biomass and grain yield. In order to see alteration,
if any, in the photosynthetic performance of plant in 2nd
generation, seeds obtained from cv RR 21 exposed to UV-B for
one season were again sown in next season. The resulting
plants did not reveal any change in photosynthetic activity
and behaved almost similar to the control plants. The study is
proposed to be extended further to some more cultivars of
wheat with a view to evaluate the sensitivity of UV-B to
different cultivars of wheat.

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MODELING AND ANALYSIS OF VEGETATION-CLIMATE INTERACTIONS
USING NEURAL NETWORKS AND GENERALIZED LOGIT MODELS

E. Siegel, M. Kandlikar and H. Dowlatabadi

Integrated Climate Assessment Program,
Department of Engineering & Public Policy,
Carnegie Mellon University, Pittsburgh, PA 15213-3890, USA

The importance of biosphere-climate interactions for energy
and moisture balances and major biogeochemical cycles is well
recognized. Climate change is expected to alter the
functioning and distribution of major ecosystems. These
changes have been investigated using global vegetation
transfer models. Typically, these models are correlative in
nature and use heuristics in the form of process based rules
to classify vegetation types for a given set of climatic and
soil variables. Based on these models and future climate
scenarios from GCMs the global distributions of ecosystems in
a 2XCO2 world are derived. In this paper, we describe
probabilistic modeling approaches that use functional
relationships between a set of explanatory variables and
occurrence of vegetation types. Probabilistic models differ
with the traditional transfer models in that they estimate the
probability of occurrence for a particular vegetation type
under different climatic and geomorphologic conditions. In
transfer models, on the other hand the response is Boolean in
nature. Therefore, probabilistic models provide a more robust
way of characterizing a variety of climate vegetation
interactions.
We use two different approaches for obtaining functional
relationship between explanatory (e.g. climatic and
geomorphologic variables) and ecosystem/vegetation occurrence.
The first approach uses a multinomial generalized logit scheme
to identify statistically significant explanatory variables
and compare relative contribution of different explanatory
variables in determining prevalent vegetation class. A major
drawback of this approach is that it does not provide good
approximation for the highly non-linear relationships between
occurrence of vegetation/ecosystems and the set of explanatory
variables. We address this concern using neural network
models. Neural networks provide computationally efficient
means for modeling highly nonlinear relationships between sets
of input and output vectors, i.e, between prevalence of chosen
ecological responses and a set of explanatory variables.
Two types of responses were used: 1) aggregated Olson ecotypes
and 2) Plant Functional Types. Considered explanatory
variables were mean temperature of the coldest and warmest
months, lowest and highest average monthly precipitation,
potential evapotranspiration, soil properties, distance to the
nearest human settlement/agricultural area and water bodies,
spatial characteristics of neighborhood and elevation.The
results of the modeling were compared to the present day
distributions of ecosystems from the Olson database. Climate
scenarios derived from the MECCA database were used to
estimate possible changes in ecosystem areas. Using a range of
estimated carbon densities for each ecosystem, we estimate the
carbon exchange between the terrestrial ecosystem and
atmosphere resulting from changes in ecosystem areas.


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APPLICATION OF PARAMETRIC STUDIES USING LIMITED AREA MODEL
IN GLOBAL SCALE MODELS

V.Sitaraman, A.Vinodkumar, R.B.Oza, T.M.Krishnamoorthy

Environmental Assessment Division
Bhabha Atomic Research Centre
TROMBAY, BOMBAY-400 085, INDIA


Current atmospheric chemistry / transport models on global scales, while
broadly successful in addressing problems of the impact of atmospheric
chemical perturbations on radiation, weather and climate, lack detailed
treatment of the various feed- back processes. Global scale models treat
chemistry and transport using highly simplified parameterization schemes
compared to meso and regional scale models and it would be useful to
incorporate the insights gained in limited area models of the feedback
processes in global models.

A one-dimensional high resolution planetary boundary layer model was
developed for detailed atmospheric chemistry and transport studies. It is
a prognostic primitive equation model with detailed radiative transfer,
surface energy balance and soil parameterization schemes and has been used
as a stand alone test model. Conservation equations of momentum, heat,
water vapour, turbulant kinetic energy and energy dissipation are solved
on a staggered expanding vertical grid. Surface boundary conditions are
coupled to soil layers using force-restore method. A detailed validation
exercise of the model was carried out using boundary layer and soil data
obtained during field experiment in Australia. Model predicted wind and
turbulence fields, surface layer and soil variables have shown good
agreement with field data over an entire diurnal cycle. The model has been
extended to consider vertical dispersion of vapours and aerosols in the
atmosphere with and without surface deposition.

It is planned to extend the model to include modules for atmospheric chemical kinetics and cloud microphysics. These are useful for
understanding the exchange processes between surface and atmosphere of
biogenic and other important chemical constituents in the perturbation of
global climate.


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TOWARDS A GENERIC MODEL OF TERRESTRIAL ECOSYSTEM DYNAMICS

S. Sitch, A. Haxeltine and I.C. Prentice

Global Systems Group, Department of Ecology, Lund University,
Ecology Building, S-223 62, Lund, Sweden
A physically consistent generic model of vegetation dynamics
is required for long-term projections of the global carbon
cycle. Such a model has been produced, and tested over the
Australian continent with good results. The model has been
constructed allowing for the maximum possible
compartmentalisation of the major ecological processes, thus
allowing flexibility with regard to future model
coupling/sensitivity experiments alternative formulations of
carbon, water and nitrogen fluxes).

The key to the model is the separate calculation of net
primary production (NPP) for different co-existing plant
functional types, followed by explicit allocation of NPP to
growth of different compartments. Vegetation is divided into
two canopy layers and three living pools [leaf, sapwood
(including coarse roots) and fine roots] plus a heartwood
pool, which are updated on an annual timestep. The carbon
fluxes are calculated on a quasi daily timestep, and summed
over the year for the annual NPP calculation. Each biomass
pool is assigned a turnover rate, with specific leaf area
related to leaf longevity. Stress induced mortality is
included explicitly. The living biomass pools and the
available photosynthate pool are further reduced due to
natural disturbance, which is treated at the regional scale as
a composite deterministic function of the weather conditions
and properties of the vegetation present. The remaining
photosynthate is allocated to the various biomass pools so as
to satisfy conditions including allometric and functional-
balance relationships.

Further development will extend the models application to the
global scale.


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INDICATIONS OF CHANGE IN GLOBAL AND REGIONAL TRENDS
OF ATMOSPHERIC MERCURY CONCENTRATIONS

F. Slemr, W. Junkermann, R.W.H. Schmidt and R. Sladkovic

Fraunhofer Institute for Atmospheric Environment Research,
KreuzeckbahnstraE1e 19, D-82467 Garmisch-Partenkirchen, Germany


In 1992 we reported an indication of global increase of
atmospheric mercury concentrations obtained from the
measurements of total gaseous mercury (TGM) over the Atlantic
Ocean during four ship cruises between 1977 and 1980 and one
cruise in 1990. The observed rate of concentration increase of
about 17,5% in the northern and 14.0% in the southern hemi-

spheres and its implications were consistent with previous
measurements of Williston in 1965-1967 and the trends derived
from analyses of dated soil, peat bog and lake sediment
records. To avoid uncertainties from the intermittent
character of ship measurements and to obtain more detailed
information about this trend, we have continuously monitored
TGM concentrations at the summit of the Wank mountain (1780 m
a.s.l.) near Garmisch-Partenkirchen in southern Germany since
March 1990. These measurements and the results of another
cruise in 1994 indicate a significant change in the trend of
global TGM concentration, with a decrease of about 22% in the
years between 1990 and 1994. The Wank data indicate that most
of this decrease occurred in the time between 1990 and 1992.
This decrease is most likely the result of reduction in coal
consumption and measures taken in the OECD countries to curb
the use of mercury.


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GLOBAL MODELLING BY POLI-LINEAR METHOD

S.R. Stepanenko and V.A. Lobanov

State Hydrological Institute, St. Petersburg, Russia


Assumption about availability of long-term variation of
climatic system and a conservation of their analysis methods
based on the theory of random stationary processes lead to
many problems which are difficult to decide in the framework
of these methods. Therefore, it may be expect that the using
for climate variations researches the theory of nonstationary
processes analysis would allowed to decide successfully many
problems of climatology and to point out some new regular
properties significantly important for the developing of the
physical climate theory.

In the paper 1 the main grounds of the nonstationary processes
are formulated which are based on the fundamental principle of
poli-linearity. The developed grounds have been used for the
determination of climate variations of surface temperature
fields and the height of geopotential H500 surface, marked in
the points of regular grid over the Northern Hemisphere. By
field it means a lot of mean monthly values during a year.
Each field is considered as a sum of two functions, one of
them presents the global pro-macro-synoptic scale. Both two
functions are determined by the equation of regression where
dependent value (function) is a field of a concrete year, but
independent value (argument) is the mean field of long-term
period. The values estimated by the equation of regression are
corresponded with the global field values and remainders are
identified with macro-synoptic scale processes. The intensity
of macro-synoptic scale processes is estimated by the
intensity of macro-synoptic scale processes is estimated by
the variance and global fields are characterized by parameters
of the equation of regression, one of these parameters
presents the mean value of global field and another one - its
gradients.

It has been shown that for air temperature a part of variation
conditioned by climatic fluctuations is about 30% of common
range of mean monthly values relatively of mean field of long-
term period, but for the height of surface H500 this part is
about 62%, in addition, more than 90% of these variations are
connected with climatic change of variance (intensity) of
macro-synoptic processes. The most values of local mean
monthly anomalies connected with the inter-year variation of
global fields' gradients are in 3 times more than variation of
mean global anomalies over the hemisphere both for a
temperature and a height of surface H500. The intensity of
macro-synoptic processes and parameters of global field are
changing interconditionaly in the time.

The application of the theory 1 and the methods 2 allows to
obtain the following procedures:
- to do a decomposition of all-time scales meteorological
processes;
- to obtain the assessments of their intensity;
- to find the empirical model of their intercommunication.

The decision of these tasks could essential favour the
development of physical climate theory and climate
forecasting.


1. Stepanenko S.R. Method of analysis of nonstationary
random processes for subsystem of control of
meteorological information
- Proceedings of World Data Centre, Obninsk, 1994.
2. Lobanov V.A., Stepanenko S.R. Methods of decomposition of
natural processes. Proceedings of All-Union Conference,
1988.

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Climate Research: Linking Natural and Social Worlds

Hans von Storch, MPI
Nico Stehr, Edmonton

At the present time, the field of study of environment-society relations, cultivated with considerable intellectual energy in the 19th century, continues to be -- despite the upsurge in interest in these issues since 1970 -- confused and held back by many obstacles.

Perhaps most prominent is the difficulty of joining within a single mode of discourse natural and social processes. As is happens, the field of climate research may be the specific issue in which advances can be made beyond mere declarations that natural and social phenomena interact in important ways and ought to be considered in relation to each other. Our paper offers observations about the complications of such an endeavor that stem both from past legacies and present divisions between the social and the natural sciences.

THE HISTORICAL PERSPECTIVE

Despite the impressions of many contemporary observers, the discussion of climate change on time scales within the "human time horizon", both for natural and for anthropogenic reasons, has had a considerable history. For example, in the last century a discussion was raging as to whether the evident variations in climate (as monitored for instance by changing water levels in the Great Salt Lake or in Caspian Sea) were due to large-scale de- and reforestation and other human activities or due to natural mechanisms, such as the output of the sun. In our days, as we all know, this venerable but almost forgotten debate resurfaced, with the anthropogenic emissions of carbon dioxide and sulfate particles being the major leverages for anthropogenic climate change.

Parallel to the discussion within natural sciences about the mechanisms and developments of climate change, there has always been a social scientific as well as political discussion about the implication of climate and climate change on society. For instance, the present IPCC is paralleled by governmental panels in the last century; current calls for action by scientific committees are reminiscent of similar statements issued at the beginning of this century by the American Association for the Advanced of Science demanding reforestation programs.

In the earlier context, the discussion about the impact of climate and climate change on people and society, was based on a concept nowadays called and widely indicted as "climatic determinism". According to this notion climatic conditions cause a wide array of social and psychological responses in an almost mechanistic manner. Thus, a stunning variety of individual and social features were seen to be dependent on climate: Longevity, political revolutions, eminence, stock market movements, insanity, health, economic activity, library circulations and so on.

On the social science side, the concept of environmental determinism was abandoned for good in the early half of this century. Most humanists and social scientists by this time had accepted arguments first advanced at the end of the last the last century that social and natural phenomena are on various grounds different phenomena. Major aspects of the emerging differentiation of cognitive agendas in science are the notion that biological and cultural evolution are not identical or that climate is a not a significant and therefore relevant determinant of societal dynamics. As the result of the divergence in scientific agendas, it now is also a contentious matter whether the knowledge obtained about the object has the potential to change the object itself.

The experience with the eugenics movement in America and, in particular, the Nazi movement in Germany, that is, with efforts to improve the human biological character through state action, clearly demonstrates the miscarriage of environmental determinism. Most attempts toargue that the natural and the social milieus are intimately linked fell victim to racist, chauvinistic and totalitarian political agendas.

Although the discussion of the impact of climate on societies did not cease abruptly in social science, it ultimately was discredited and vanished almost without trace as a largely compromised line of inquiry. >From 1945 forward, the separation between social and natural phenomena has become almost complete and taken-for-granted on both sides of the border, in the social as well as in the natural sciences. Natural sciences and social sciences went different ways, developed different paradigms, and communication between the two types of sciences came to a halt. They did not form an intellectual division of labor but more or less disjoint universes of discourse.

THE RESPONSE TO CLIMATE CHANGE

In the contemporary world, climate change is "real" in at least a dual sense: As likely an ongoing process in the natural world - but also as genuine in the sense that it is perceived as real by the public and that climate change has become a significant social and poltical force. The understanding of this situation, and the design of policies adequate for both the natural and the social world, represents a new challenge that requires natural and social scientists to join forces. But because of the legacy of the rigid split between natural and social sciences, science as a whole is poorly prepared for dealing with the interaction between climate and society. The social sciences have mainly ignored the "climate topic". In the few instances where this is not the case, the field is dominated by approaches that continue to link natural and social phenomena in models relying on a mechanistic conception of deterministic interactions and disregard the specifics of social dynamics.

Discourses based on such models, in modern terms: "integrated assessment studies", represent the danger of a return to climatic determinism. Such models have become increasing en-vogue. They operate on different levels of abstraction, couple subsystem models of different levels of reality and of often insufficient consistency. They share a common, crucial assumption, namely that the relevant information can be defined, observed, quantified, and transported unaffected by social dynamics into the social arena where it is eventually used to define adequate socio-political responses.

We doubt that such an approach is effective and claim that it is flawed by a fundamental misunderstanding about the societal character and role of "information". Even if we would be able to determine the state of the natural world in a Hamiltonian sense (state and momentum known in all details) this scientific knowledge would undergo the transformation into its "social construct" conditional upon the state of society.

It is only in recent years that empirical studies have been undertaken to map the social construct of climate and climate change and to understand its construction. These studies allow for a description of people's understanding of the climate problem and of social dynamics which underpin the metamorphosis of natural scientists' information. Characteristic results are a frequent misunderstanding of greenhouse gas accumulation in the atmosphere as being a "pollution" problem (which can be dealt with filters, and which has adverse effects on health) as well as a failure to distinguish between extreme events and gradual climate change.

OUTLINE

In the present talk, we outline the historical perspective, discuss the background for the split between natural and social sciences, demonstrate examples of modern "reductionism" and empirical evidence of the present-day reality of the social construct of climate and climate change.

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A STUDY ON THE SOIL MOISTURE CONDITIONS
IN NORTH CHINA


Gao Suhua and Mao Fei

Chinese Academy of Meteorological Sciences,
100081 Beijing, P.R. China

see faxed text


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LATE QUATERNARY CLIMATIC CHANGES INFERRED FROM CARBON
ISOTOPE ANALYSES OF PEATS IN SOUTHERN INDIA

R. Sukumar1, G. Rajagopalan1, R. Ramesh2, R.K. Pant2 and G.
Rajagopalan3
1Centre for Ecological Sciences, Indian Institute of Science
Bangalore - 560 012, INDIA
2Physical Research Laboratory Navrangpura, Ahmedabad - 380 009,
INDIA
3Birbal Sahni Institute of Palaeobotany, Lucknow - 226 007,
INDIA

The vegetational and climatic changes of the late Quaternary
are recorded in peat deposits of tropical montane (> 2000 m
above m.s.l.) regions of southern India (Sukumar et al.,
1993). Stable carbon isotope analyses of peats, from
Sandynallah in the Nilgiri hills, dating back to 20,000 years
reveal distinctive changes in the proportion of C3 and C4
photosynthetic plant types. This may reflect changes in soil
moisture (and hence precipitation) and atmospheric carbon
dioxide (Robinson, 1994). Some of the key global climatic
events of the past are also indicated here from the carbon
isotopic evidence. During the last glacial maximum (LGM), ca.
18,000 years BP, characterized by low atmospheric CO2 levels
(Barnola et al., 1987), and lower mean temperatures, there was
a dominance of C4 grasslands, indicating arid conditions.
Deglaciation seems to have occurred in two stages, at ca.
15,000 year BP and again at 10,000 years BP. The latter
corresponding to the Holocene Optimum, a period characterized
by higher temperature and precipitation in the Indian
sub-continent (Van Campo et al., 1982), and a spread of C3
vegetation indicative of moist conditions. A short moist phase
ca. 5500 years BP, corresponding to the Altithermal or
Hypsithermal phase, and a distinct trend towards aridity and
spread of C4 vegetation from 4000 years BP are also seen.
Higher resolution sampling of similar sites in the tropics,
and extending the analyses to oxygen isotopes of peat
cellulose, may help decipher the interrelationship of
atmospheric CO2, temperature, monsoonal precipitation, soil
moisture and vegetation change in the past.

References:

Barnola, J.M., Raynaud, D., Korotevich, Y.S., Lorius, C.
Nature, 329:408-414 (1987).
Robinson, J.M. Nature, 368:105-106 (1994).
Sukumar, R., Ramesh, R., Pant, R.K., Rajagopalan, G. Nature,
364:703-706 (1993).
Van Campo, E., Duplessy, J.C., Rossignol-Strick, M., Nature,
296:56-59 (1982).


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GLOBAL VEGETATION CHANGE IN RESPONSE TO CLIMATE CHANGE
DUE TO DOUBLING ATMOSPHERIC CARBON DIOXIDE

T. Sweda1, T. Kodaira1 and A. Kitoh2
1Department of Biological Resources and Environment, Nagoya
University, Chikusa, Nagoya 464-01 Japan

2Meteorological Research Institute, Tsukuba, Ibaragi Pref. 305
Japan

A computer-aided vegetation mapping system (CAVM) was
developed, and with which a projection of global vegetation
change in response to possible climate change due to doubling
atmospheric carbon dioxide (CO2) was made.
Given an input of a set of climatic data observed at limited
number of stations world-wide, this CAVM system spherically
interpolates the climatic data, element by element, on to an
evenly spaced grid system of 1 degree latitude by 1 degree
longitude, giving altitudinal allowance for average lapse rate
with reference to a build-in digital terrain map, converts
them into potential vegetation type at each of 64,800 grid
points according to the Koppen's system of climate/vegetation
classification, and finally maps the the potential vegetation
of the globe. The possible global vegetation change in
response to CO2-doubling climate change was estimated by
feeding two different set of climate data, one corresponding
to 1*CO2 and the other to 2*CO2.

As the 1*CO2 climate, monthly mean temperatures and monthly
precipitations at some 2,000 weather stations world-wide
averaged over 30 years up to 1958 were fed, while the
estimates of corresponding climatic elements projected by a
Meteorological Research Institute General Circulation Model
(MRI-GCM) were used as the 2*CO2 climate. This MRI-GCM,
coupled with a 50-m oceanic mixed layer, energy balance
sea-ice model, predicts global average increases of 4.9 degree
C in annual mean temperature and of 122 mm in annual
precipitation toward the equilibrium climate with 2*CO2.
This numerical experiment resulted in an explicit vegetation
change over the Globe totaling 4.90 giga-hectare (Gha), i.e.
approximately 1/3 of the total global land area of 15.4 Gha
including Antarctica and Greenland. The most characteristic
change occurred to the Polar Climate Zone (E) which shrunk by
0.7 Gha or by 27.7 %. Accordingly the rest of the
climate/vegetation zones moved poleward, resulting in an
expansion especially of the Tropical Climate Zone (A) by 0.5
Gha followed by that of the Boreal Climate Zone (D) by 0.2 Gha
while the Arid (B) and Temperate (C) Zones remained almost the
same in size by invading as much as being invaded by the
neighboring vegetation types.

Within each climate/vegetation zone, the most conspicuous
change was relative decrease in more moist types of
vegetation, i.e. those subdivisions with subscript "f" for
humid (feucht) throughout the year in the Tropical (A),
Temperate (C) and Boreal (D) Climate Zones, and the Steppe in
the Arid Climate Zone (B), and relative increase in dryer
types of vegetation, i. e. those with subscripts w for
winter-dry, "s" for summer-dry and "m" for monsoon in Zones A,
C. and D and the Desert in the Arid Zone.

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CARBON STORAGE IN BOREAL FORESTS

M.T. Sykes1, D.T. Price2, I.C. Prentice1 and M.J. Apps2

1Global Systems Group, Ecology, Lund University, S-223 62 Lund,
Sweden

2Canadian Forest Service, Natural Resources Canada, Northwest
Forestry Centre,
5320-122 Street, Edmonton, Alberta, Canada T6H 3S5

We compare estimates of above-ground carbon storage in boreal
forest ecosystems using two types of model. We use the same
two models - the potential natural vegetation model BIOME 1.1
(Prentice et al 1993) and the forest dynamics model FORSKA 2
(Prentice, Sykes & Cramer 1993) - to simulate boreal forest
landscapes in Sweden and central Canada (Alberta,
Saskatchewan, Manitoba). BIOME 1.1 uses ecophysiological
constraints on the distribution of different plant functional
types to predict biome distributions at regional to global
scale, then assigns conventional values for carbon storage in
different compartments for each biome. FORSKA 2 uses species
parameters and a modified gap model approach to predict forest
composition and biomass dynamics explicitly, at a landscape or
local scale. In this application FORSKA2 was run to
equilibrium assuming a prescribed disturbance regime to stand
for either natural disturbance or harvest.

Above-ground carbon storage estimates from the models were
compared to estimates of present day carbon storage based on
measurements. For Sweden we used regional averages from
inventory data. For Canada we used output from the CBM-CFS 2
model ( Kurz et al 1992) which has been extensively validated
against forest inventory data.

Although the biome distributions simulated by BIOME 1.1 were
good in both regions, the carbon storage values assigned to
each biome were evidently far too large (up to 4 times in some
areas).

FORSKA 2 generated realistic descriptions of the species
composition and biomass of selected forested landscapes in
both regions. FORSKA 2-simulated estimates of carbon stored in
these forests were similar to or at most ~20% lower than the
estimates based on measurements. Some of these differences can
be related to the point sampling nature of the FORSKA 2
simulations compared to the aggregation of regions in the
forestry inventory data. Others can relate to imprecisely
specified disturbance rates.

References

Kurz, W.A., Apps, M.J., Webb, T.M. & McNamee, P.J. 1992 The
carbon budget of the Canadian forest sector: Phase 1.
Northern Forestry Centre, Edmonton, Northwest Region
Information Report NOR-X-326, Forestry Canada, Ottawa.
Prentice, I.C., Sykes, M.T. & Cramer,, W. 1993. A simulation
model for the transient effects of climate change on
forest landscapes. Ecological Modelling 65, 51-70.
Prentice, I.C., Sykes, M.T., Lautenschlager, M.J., Harrison,
S.P., Denissenko, O & Bartlein, P. 1993. Modelling global
vegetation patterns and terrestrial carbon storage at
thellast glacial maximum. Global Ecology and Biogeography
Letters 3, 67-76.


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BIOTIC ZONES DURING THE LAST GLACIAL CYCLE COMPUTED
FROM SIMULATIONS WITH THE CSIRO COUPLED GCM

Jozef Syktus

CSIRO Division of Atmospheric Research
Melbourne, Australia,

Climate changes during the last glacial cycle were driven to a
large degree by a combination of greenhouse and orbital
forcing. Greenhouse forcing occurs primarily through longwave
radiative effects which are relatively homogeneous in space.
Orbital insolation changes are inhomogeneous in both space and
time and, although they have a large seasonal effect, largely
cancel over the annual cycle. This work describes the results
of a series of equilibrium experiments aimed at simulating
gross changes of the climate over the past 130 kyr years due
to orbital and greenhouse forcing. Equilibrium experiments
(each 30 years long) were performed for 0, 6, 9, 11, 21, 104,
114, 115, 116, 126, 131 kyr BP. A coupled dynamic upper ocean
and atmospheric GCM has been used at R21 horizontal
resolution. The inclusion of a dynamic ocean model enables us
to realistically simulate the response of the earth's climatic
system. The model successfully simulates the initiation of
glaciation during the Last Interglacial to glacial transition
(ca. 116 kyr BP) and reveals a strong monsoonal contrast
driven primarily by the precessional component of orbital
forcing.
An important component of this work has been the use of the
modified Holdridge life zones (biomes) classification
(Henderson-Sellers, 1991) to derive the 'natural' ecosystems
changes during the last 130 kyr. The computed biomes show
large contrasts at high latitudes between the Last
Interglacial (126 kyr) and early glacial (ca. 114-116 kyr) and
also between the Holocene and the Last Glacial maximum. On the
other hand, the simplified Holdridge life biomes
classification is rather insensitive to a large changes in
monsoonal precipitation amounts and the use of more elaborate
model of ecosystems is warranted.
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TOWARDS INCORPORATING A MODEL OF THE CARBON CYCLE
IN A GLOBAL CLIMATE MODEL

J. A. Taylor

Centre for Resource and Environmental Studies
Australian National University, Canberra ACT 0200, Australia


If we are to incorporate models of the global carbon cycle
into climate models we must first understand the processes
governing the present day fluxes of greenhouse gases between
the biosphere and atmosphere. A key uncertainty in
understanding and managing the global carbon cycle is the role
played by the biosphere in taking up and releasing atmospheric
CO2. The sources and sinks of atmospheric CO2 were investigated
using a global 3-dimensional Lagrangian tracer transport
model. The transport model is based on observed global wind
fields at 2.5 degrees resolution obtained from ECMWF. Model
runs, based on studies performed as part of the international
TRANSCOM model intercomparison, were undertaken using two
source distributions representing key components of the global
carbon cycle. One model run was performed simulating the
release of CO2 from fossil fuel combustion during the
mid-1980's. The second run examined the uptake and release of
CO2 from the natural biosphere and assumed no annual averaged
net uptake or release of CO2. Model predictions of the
latitudinal gradient in atmospheric CO2 can be compared with
observations to infer sources and sinks of atmospheric CO2.
Model results indicate that during the 1980's a sink for CO2 in
the biosphere at middle to high latitudes in the northern
hemisphere is unlikely to be large whereas a substantial sink
in the tropics is clearly a strong possibility.


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CONSTRAINING TERRESTRIAL NET PRIMARY PRODUCTION FROM
ESTIMATES OF HISTORICAL PLANT CARBON UPTAKE

M. V. Thompson1, J. T. Randerson1, C. B. Field2, and C. M.
Malmstrom

1Department of Biological Sciences, Stanford University
Stanford, CA 94305, USA

2Carnegie Institution of Washington, Department of Plant
Biology, 290 Panama Street, Stanford, CA 94305, USA

The impact of increased net primary production (NPP) on
terrestrial plant uptake was modeled using the CASA biosphere
model. Taking advantage of the coupled nature of NPP and soil
respiration, and the resulting lag time between them when NPP
is varying, we have used modeled results for the historical
record in terrestrial carbon uptake to model changes in NPP
and the increase in the seasonal component of the atmospheric
CO2 oscillation. To maintain a terrestrial sink, NPP must not
only increase to meet the difference between it and
respiration, but it must continue to increase, since
respiration is continuously catching up to NPP. We observed
that various regions of the world would respond differently to
a relative increase in NPP. The absolute size of the sink is
due both to the turnover time of the biosphere and to the
magnitude of NPP. Areas with high carbon turnover times and
high NPP should produce the largest sink, whereas the lowest
sink should occur in areas with low turnover times and low
NPP. In addition, wherever NPP is increasing, the size of the
biosphere is also increasing. This will result in a larger
absolute amplitude in the seasonal component of the CO2 record,
in proportion to the increase in NPP and the resulting (but
delayed) increase in soil respiration. Our index of the
seasonal amplitude is derived from the total amplitude of
terrestrial carbon exchange.
We used the annual plant uptake estimates from 1982 to 1992 of
Francey et al. (1995) to prescribe the annual carbon sink.
Initially, we set the biosphere to equilibrium with a global
annual NPP of 50 Gt C and no initial terrestrial carbon sink.
We observed that annual NPP could increase as much as 8% over
the eleven year period, The increase in the amplitude of the
CO2 oscillation could be even stronger, where the southern
hemisphere amplitude would increase by as much as 15% over the
eleven year period and the northern hemisphere amplitude by
8%.
Under different initial conditions, such as 60 Gt NPP and a
1.6 Gt carbon sink, we observed an increase in NPP of only 5%.
The southern hemisphere amplitude increases by 9% and the
northern hemisphere amplitude increases by 5%. We discuss
possible explanations for this behavior.

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GLOBAL IMPACT OF AFRICAN AEROSOLS,
PART I: THREE-DIMENSIONAL TRANSPORTS FROM SOUTHERN AFRICA


P D Tyson1, M Garstang2 and R Swap2


1Climatology Research Group, University of the Witwatersrand,
PO Wits, 2050, South Africa

2Department of Environmental Sciences, University of Virginia,
Charlottesville, VA 22903

A method for determining atmospheric transports of aerosols
and trace gases is described. Large numbers of kinematic
trajectories based on Lagrangian advection are calculated from
given points of origin after taking vertical velocities and
atmospheric stability into account. Average transport plumes
for specified conditions are constructed to include at least
95 per cent of all trajectories. Both individual trajectories
and integrated plumes are shown to be controlled by the
thermodynamic structure and stability layering of the
atmosphere. From knowledge of the 3-dimensional plume
structure at given longitudes and the advection velocity of
the plume from the point of origin, volume transports are
determined. From these mass fluxes may be estimated if
concentrations are known or can be modelled.

Case studies from the TRACE-A and SAFARI experiments show
excellent agreement between observations and modelled
individual trajectory pathways and go a long way to explaining
transport characteristics in the region. Seasonality is dealt
with by linking transport patterns to circulation types using
variation of the circulation types to determine a monthly
transport climatology. Four circulation-linked transport
modes are found to be dominant. These are transport associated
with stable semi-permanent subtropical continental
anticyclones, with transient ridging highs originating in the
westerlies to the south of South Africa, travelling baroclinic
mid-latitude westerly disturbances and quasi-stationary
barotropic tropical easterly wave disturbances originating to
the north of the subtropical anticyclones.

The extent of atmospheric recirculation over Africa south of
150 is examined for vertically-integrated surface to 800 hPa
and 700 to 500 hPa transport. Mass fluxes of aerosols at these
levels into the Atlantic Ocean region west of 100E and into the
Indian Ocean area to the east of 350E are presented. The
framework is established to determine regional and global
effects of aerosol fluxes out of Africa. These are considered
in Part II of the paper.

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ESTIMATING THE REMINERALIZATION RATES IN THE OCEAN
WITH A NEW BASIN EXTENDED ADVECTION/DIFFUSION
HIGH LATITUDE SIMPLE MODEL (Be-HILDA).

H. L. VillagrA0n 1 and G. Shaffer 1,2
1Department of Geophysics, Niels Bohr Institute for Astronomy,
Physics and Geophysics, University of Copenhagen, Haraldgade
6, DK-2200 Copenhagen N, Denmark.

2 Born Institute for Ocean and Climate Studies, Holma
4235,
45400 Brastad, Sweden


The HILDA model (Shaffer and Sarmiento, 1995) has been
extended to include two main low latitude basins, the Indo-
Pacific and Atlantic Oceans and two high latitude regions: the
polar North Atlantic and the Southern Ocean.

This extension of the basic HILDA model, allows the
consideration of the very distinct dynamics of each deep water
formation region and the exchange between these regions and
the rest of the ocean. In the new model, the number of free
parameters is about doubled (10 for ocean physics and 6 for
the organic pump). This increase in degrees of freedom is
"compensated" by the extra information contained in the very
different mean property distribution for the Atlantic compared
with the Indo-Pacific. Values for the physical parameters in
this steady state model are constrained by GEOSEC 14C and
Levitus temperature data. New production, subsurface
remineralization rates and distributions, are constrained
byusing GEOSEC PO4, NO3 and O2 data. This approach enables
estimates to be made of how the organic pump works in each of
the four basins considered.

The results of Be-HILDA are compared with those of the
simpler HILDA model and with other studies of ocean
remineralization.

References:

Shaffer G. and J. L. Sarmiento (1995). " Biogeochemical
cycling in the global ocean 1. A new, analytical model with
continuos vertical resolution and high-latitude dynamics ".
Journal of Geophysical Research. Vol. 100, No C2: 2659 - 2672.


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THE ROLE OF DRAINAGE BASIN DYNAMICS IN EMERGING EARTH SYSTEM MODELS
C. V. Smarty, B.J. Peterson3, B. Fekete1, and A. Schloss
1Institute for the Study of Earth, Oceans, and Space,
Morse Hall, University of New Hampshire 03824, USA
2Department of Earth Sciences,
James Hall, University of New Hampshire 03824, USA
3Ecosystems Center, Marine Biological Laboratory,
Woods Hole, Massachusetts 02543, USA
The land-based hydrologic cycle has received significant
attention with respect to land- atmosphere exchanges at
continental and global scales. Indeed, general circulation
models (GCMs) and, more recently, regional atmospheric models
of increasing sophistication have been widely employed to
understand how complex landscapes, including those altered by
humans, regulate surface water and energy fluxes. An important
component of this cycle, namely fluvial transport for both
water and constituents, has received significantly less
attention within an Earth Systems Modeling (ESM) context. This
is paradoxical, given that a). the magnitude of anthropogenic
loadings of several biogeochemical constituents into drainage
basins and their associated rivers, relative to natural
fluxes, is commonly far greater than the loading of CO2 into
the atmosphere, b).numerous case studies have demonstrated a
clear correspondence between such loadings and the alteration
of biogeochemistry and ecosystem function in freshwater and
coastal ecosystems, and c). the heavy dependence of human
society on the timing, quantity, and quality of water
resources. We will briefly summarize the rationale for
incorporating a drainage basin perspective into ESMs,
illustrate some major modeling approaches, and then offer a
framework for developing models that couple the transport of
water and processing of biogeochemical constituents suitable
for use within ESMs. At the heart of this framework is a
global, GIS-based network topology, representing nearly 3800
exorheic and endorheic river systems at 30-minute spatial
resolution. We will demonstrate use of this data base through
a series of examples in which continental and global-scale
water and constituent fluxes are mapped and quantified.

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CHANGES IN THE WATER STORAGE OF LAKE
GOSCIAZ AND CHARACTER OF HUMID PHASES DURING THE HOLOCENE (#323)Leszek
StarkelInstitute of Geography and Spatial Organization, Polish Academy
of Sciences, St. Sw. Jans 22, PL31018 Krakow, Poland Various systems
and sediments deliver different informations on changes in the water balance
during the Holocene.The formation of lakes in the dead ice depressions
in N-Poland made possible
to study the lake level fluctuations and changes in the water storage. In the case
of transfluent Lake Gosciaz the indicators of water level changes, deposition
of lacustrine sediments and overgrowing were taken into consideration. The late
Vistulian storage of about 5500x103m3 decreased until present by about 56%.
The registered water level changes by ca 1 m caused change of water storage declined
from ca 1300 to 675x103m3 from Alleroeäd until present.These rises
of water level coincide with
more humid phases registered in the vegetation changes, rate of the peat growth,
floods, frequency of landslides and debris flows. The floods in the upper Vistula
Basin were created during the continuous rainfall. On the contrary the debris
flows are connected with high intensity downpours. Large and deep landslides
may be formed during extremely wet years.All these informations indicate
that during the so called wet phases of the Holocene the frequency of various
extreme events was very high.
This may be explained by the coincidence with changes in the air mass circulation
as well as by the increased volcanic activity. The summarising effect of
all these events is reflected in the rises of the lake water level.


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BIOME AND CARBON STORAGE ESTIMATION FROM EASTERN NORTH
AMERICAN POLLEN DATA: A TEST OF METHODS

T. Webb III, R. Summers, and J. Williams

Department of Geological Sciences, Brown University,
Providence, RI 02912-1846, USA

Paleoecological data provide a rich source of information for
testing the results of global biome and general circulation
models. BIOME1 and BIOME2, the biome models developed by
Prentice and co-workers, relate climate data to plant
functional types and then estimate the biomes from
combinations of the dominant plant functional types. When
applied to the simulations of past climates from general
circulation models, BIOME1 and BIOME2 provide estimates of
past biomes. In related research, Prentice and co-workers have
classified pollen data from Europe in terms for plant
functional types and developed methods for estimating biomes
from these data for today and 6000 years ago. We have applied
their method to mapped pollen data from eastern North America
for today, 6000, 14,000, and 21,000 years ago and used our
data and refinements to the method to test the general
procedure. Part of our test consists of comparing the newly
derived maps of past biomes to previous maps of the biomes
estimated from modern-analog methods that relate fossil and
modern pollen samples. The maps of the past biomes have also
allowed us to use Olson's data to make rough estimates for the
changes in carbon storage across eastern North America since
the last glacial maximum 21,000 years ago. Lessons gained from
this research will help us in applying the methods to the
Global Paleovegetation Data Set that is being developed from
paleoecological data for 6000 and 21,000 years ago and used to
test the results from BIOME1 and BIOME2.

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THE POSSIBLE EFFECTS OF CHANGING LAND SURFACE TYPES
ON THE LOCAL ENERGY AND WATER BALANCE

Helin Wei & Congbin Fu

Institute of Atmospheric Physics, Chinese Academy of Sciences,
Beijing, China


Changing land surface types may have important consequences
for the climate system. Predicting even the local, immediate
effects of changing land surface types on the local energy and
water balance has been difficult, because the land-surface
parameterization schemes used previously in climate models
have been inadequate and the resolution of GCM has been too
coarse to adequately describe mesoscale forcings such as
vegetation gradient and to yield accurate regional climate
detail. The grassland is a major ecosystem in the northern
China playing the crucial role in the surface energy and water
budget. Inclusion of a Biosphere and Atmosphere Transfer
Scheme (BATS) into the National Center for Atmospheric
Research (NCAR) Regional Climate Model (RCM) permits an
exploratory study of the possible effects of changing land
surface types. Based on the observation of desertification in
this area, a numerical experiment is designed in which a 7-day
integration that all of the grassland in the northern China is
replaced by the desert. The results show that the hydrologic
cycle was weakened, with less precipitation and evaporation;
and the energy balance was changed also, with less net
radiation and latent heat fluxes and an increase sensible heat
fluxes from the surface which results in an increase in
surface temperature. These results are relevant to the changes
of parameters in BATS due to changing land surface. Some
detail patterns of the effects of changing land surface on
local energy and water balance have been simulated.

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DYNAMICS OF PRIMARY PRODUCTION AND SOIL ORGANIC MATTER
OF TYPICAL STEPPE IN THE XILIN RIVER BASIN
OF INNER MONGOLIA AND THEIR RESPONSE TO CLIMATE CHANGE

Xiao Xianming1 and Chen Zuozhong2

1The Ecosystems Center, Maine Biological Laboratory,
Woods Hole, MA 02543, USA

2Plant Ecology Laboratory, Institute of Botany, Chinese Academy
of Sciences,
141 Xizhimenwai Street, Beijing 100044, China

At the site level, we use the CENTURY plant-soil ecosystem
model and Landsat remote sensing to estimate aboveground
biomass of Leymus chinense steppe and Stipa grandis steppe in
the Xilin river basin, Inner Mongolia, China. Century
simulation results replicated well the seasonal dynamics and
interannual variation of aboveground biomass of these steppes
in the period of 1980-1989. Simulated soil organic matter is
within F125% of the observed data. NDVI-derived aboveground
biomass were within F125% of the observed field biomass at the
L. chinense site and S. grandis site, using Landsat TM
imageries on July 31, 1987 and August 11, 1991.

The effect of global climate change and elevated CO2 on the
steppe were examined, using the climate fields from GCMs of
CCC and GFDL under 1*CO2 and 2*CO2 scenarios. Climate change
results in considerable decrease of primary production and
soil organic matter of L. chinense steppe and L. grandis
steppe. L. chinense steppe was more sensitive to climate
change than S. grandis steppe.

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MODELLING OF THROUGHFALL BASED ON CANOPY WATER BALANCE


Yi-Jun Xu

Institute for Soil Science and Forest Nutrition
University of Goettingen, Germany
Buesgenweg 2, 37077 Goettingen, Germany


A modelling system for calculation of throughfall was
developed based on physical description of canopy water
balance. The model is able to estimate major water components
of canopy in account such as interception loss, remaining
water on canopy, drainage rate and throughfall. The
application of this model was carried out for an old Norway
spruce stand in the Solling research area, Germany.

Central to this model is the assumptions: 1) There is an
amount of water required to wet all level surfaces of canopy,
canopy saturation in mm per leaf/needle area per ground unit.
Its quantity is dynamic and, above all, depends on wind speed
above or within canopy, dynamic canopy saturation, S*. It is
assumed that S* could be estimated in an exponential manner as
wind speed (u) decreased

S*3DSmax*exp(alfa*u**2)*-1

Under the condition of still air, which is rarely present, S*
is equal maximal canopy saturation, Smax, otherwise, S*
decreases as wind speed is increasing. The slope of the
decrease depends on coefficient alfa which may be considered
as a leaf/needle characterization. 2) The interception loss is
assumed as the potential evaporation proportional (Ep) to the
canopy storage for the storage less then the dynamic canopy
saturation (Cevaporation for storage equal or greater then dynamic canopy
saturation (C 3D or > S*, E3DEp), where the potential
evaporation is calculated by Penman-Monteith for a wet
surface.

The simulated results, in one hour time steps, were tested
against 36 months' throughfall records (1990-1992) on the
study site. The Comparison of observed and predicted through-

fall shows that the simulation is very successful (R23D0.99)
and the difference in total up to end of the simulation is
less than one mm. A relative higher deviation between observed
and predicted throughfall presents in the periods of fall and
winter, and might be caused by the fact that the amount of
water appeared as fog, occasionally in fall and winter, can
not be measured in rainfall by automated raingauge.
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MODELLING OF PRIMARY PRODUCTIVITY IN ARABIAN SEA

K.S.Yajnik and M.K.Sharada

CSIR Centre for Mathematical Modelling and Computer
Simulation, N.A.L. Belur Campus, Bangalore - 560037, INDIA

Marine biota play an important role in the global carbon
cycle. Ocean-carbon cycle models coupled with ocean-atmosphere
general circulation models can describe the long-term response
of ocean system to global change scenarios. As a first step
towards the development of such coupled, basin scale models of
ocean circulation and biogeochemical cycles, we have been
studying a class of dynamical models of marine ecosystem for
tropical conditions at selected stations in the Arabian Sea.
It is well known that Arabian Sea experiences extremes in
atmospheric forcing, which results in greatest seasonal
variability observed in any ocean basin. The link between the
physical forcing and the supply of organic matter to deep
waters is the planktonic food web, which has special features
here and merits investigation.
The central problem in modelling the primary production is to
model the interaction between the various components of the
ecosystem with climatological factors like solar radiation,
mixed layer depth, upwelling etc. We have used a nonlinear
7-component model of the marine ecosystem proposed by Fasham
et al. (1990) to estimate the primary production in Arabian
Sea. Simulations were carried out for the mixed layer for
climatological variation of solar radiation, mixed layer depth
and upwelling velocity to study the sensitivity to selected
parameters. Two parameters affecting the nutrient supply,
namely, subsurface nitrate concentration and diffusion
parameter, were varied. In addition, three ecosystem
parameters, namely, asymptotic grazing rate of zooplankton,
grazing preference of zooplankton and detritus sinking rate
were also varied. Simulations were carried out for 4 and 6
years which clearly indicate that the averages in the fourth
year are to a very good approximation equal to those in the
sixth year. We have therefore used the fourth year averages to
determine annual averages.
Annual averages of all components as well as fluxes have been
obtained to give a quantitative picture of sensitivity of the
ecosystem from the carbon-flux point of view to various
parameters. The system is found to be most sensitive to
asymptotic grazing rate and subsurface nitrate concentration.
It is also found that variation of chlorophyll with subsurface
nitrate concentration is nonlinear. The following table shows
the annual averages of new production at six stations in
Arabian Sea for two values of asymptotic grazing rate of
zooplankton, g. Stations A to D are on a transect normal to
the coast of Oman close to proposed long stations of US-JGOFS
and the stations E and F are also close to US-JGOFS and Indian
JGOFS transects. It is seen from the table that doubling of
the asymptotic grazing rate results in decrease of new
production by 20-40%.
Annual Average New Production mg C /cu. m/ day Station
A B C D E FLat. N 18 17 16 15 10 19Lon. E 58 60 62 65 65 67 for g3D1 (1/d) 10.8 10.6 7.4 5.5 4.
8 7.
4for g3D2 (1/d) 6.7 6.8 5.8 4.8 3.
9 5.
1

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MATHEMATICAL MODELLING OF THE CARBON DIOXIDE OCEAN-ATMOSPHERE
FLUX VARIABILITY IN CONNECTION
WITH ROLE OF POLAR MARINE BIOTA AS POSITIVE FEEDBACK
IN GLOBAL CARBON CYCLE

E.V.Yakushev and G.E.Mikhailovsky

P.P.Shirshov Institute of Oceanology, Russian Academy of
Sciences
23 Krasikova Street, Moscow, 117851, Russia

Study of the carbon global cycle is very important in the
context of its impact upon the climate of the Earth. According
to up-to-date information the global carbon cycle is not
balanced, and therefore so-called 'missing sinks' must exist.
Their revealing is one of the most important tasks in the
context of global climate change. The results of our numerical
experiments with model of polar marine epipelagial ecosystems
and new interpretation of field observations disclosed that
polar biota can play the role of one of such 'sinks'.
The influence of the marine biota on the ocean carbonate
system was investigated with a mathematical model where
parallel chemical-biological cycles of carbon, nitrogen,
phosphorus and oxygen were parameterized. The model was
calibrated as an example of the White Sea, where we carried
out the field investigations.
On the base of numerical experiments we showed that in the
high latitudes of the ocean, the amplitudes of annual
variability of such parameters as oxygen, pH, pCO2, are caused
by chemical-biological processes for 1/3 of their values
(about 2 ml/l for oxygen; 0.05 for pH; 60 ppm for pCO2). The
influence of biota resulted first of all in changes in pH
values during the phytoplankton 'bloom' period, that followed
to displacement of the carbonate system balance: the temporary
increasing of carbonate ion and decreasing of gaseous carbon
dioxide. Because of it, a temporary anomaly in the
ocean-atmosphere exchange flux rate took place.
On the base of our and others field investigations in the
Arctic and the Antarctic it was established that there is
intensive phytoplankton 'bloom' on the undersurface and in
pores of marine ice in early spring before an icemelting, if
it takes place at all. The amplitude of this "bloom" is at
least equal to one of the subsequent 'bloom' in ice-free water
column after icemelting. But duration of the ice 'bloom' is
about four times more than ice-free water one. As a result,
the commonplace that the first and main phytoplankton "bloom"
happens only after icemelting was disproved. Hence, there are
strong grounds to suppose that biomass and production of
phytoplankton are quite important not only in regions of
Arctic and Antarctic where ice disappears (if only for a short
time) but also under the pack ice around the Antarctica and,
that is more significant, under the pack ice cover of the
Arctic Ocean.
It was estimated that the total value of pCO2 extra consumed by
the ocean during the phytoplankton "bloom" was estimated as
2.4-2.7 mol/m2. This result can be typical to all the Polar
latitudes. Consequently, consumption of CO2 by high latitude
phytoplankton is maybe one of the important "missing sinks" in
carbon global budget.
Moreover, polar marine biota, as one of 'sinks', forms
necessarily global positive feedback: warming of climate leads
to reduction of polar ocean ice area, and as a result to
decrease of CO2 consumption by polar ocean, and to increase of
CO2 in the atmosphere, and consequently to warming of climate.

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MATHEMATICAL MODELING OF ANAEROBIC CONDITIONS FORMATION IN
NATURAL WATERS AS AN EXAMPLE OF THE BLACK SEA

E.V.Yakushev, L.N.Neretin and N.V.Vakulenko

P.P.Shirshov Institute of Oceanology, Russian Academy of
Sciences
23 Krasikova Street, Moscow, 117851, Russia

The main goal of this work was to describe biogeochemical
cycles of nitrogen and reduced sulfur in natural aquatic
ecosystems with a mathematical model. The subject of modeling
estimations was inter-relation zone between oxic and anoxic
waters and hydrogen sulfide zone of the Black Sea.
The proposed mathematical model describes the variability of
chemical elements: oxygen, nitrogen (nitrate, nitrite,
ammonia, organic nitrogen) and sulfur (sulfate, thiosulfate
and sulfite, elemental sulfur, sulfide). It considers the
processes of ammonification, nitrification, nitrate reduction,
denitrification, thiodenitrification, sulfate reduction and
hydrogen sulfide oxidation. All compound distributions are
calculated on the base of one- and two-dimensional equation of
diffusion with sources according to the task. Transformation
of these compounds have been accepted to proceed
microbiologically in the model. The dependencies of the
transformation rates upon the oxygen concentration were
parametrized by the semiempirical functions. Latter were set
according to the nature conditions.

Model results clearly demonstrate the process of organic
matter oxidation in progress. When organic matter quantity
excessively increases, its oxidation may use up first of all
oxygen, then all nitrates, and finally takes place because of
sulfates. It results in hydrogen sulfide zone formation.
Similar effects can be observed when the water flow rich with
oxygen is decreased by the peculiarities of the bottom relief,
as in fjords or after dam constructing.

On the base of model the inorganic reduced sulfur and nitrogen
fluxes in the oxic-anoxic interface zone and contribution of
biogeochemical transformation processes and hydrophysical
factors in the compounds distribution were evaluated. Model
estimations confirm that the existence of reduced conditions
in the Black Sea mainly controlled by the peculiarities of
organic matter decay (consequence of oxidants consumption)
accompanied by restricted aeration of deep waters. The value
of hydrogen sulfide flux in the Black Sea sediments is
incomparably less then in water pool. That is why all main
transformation processes of sulfur are concentrated in the
water column and particularly in the interface zone. The model
applied to the description of sulfur cycle in this zone
allowed to investigate common features and peculiarities of
hydrogen sulfide column existence of the basin at all. The
model was calibrated using the observed data on the components
vertical distribution in the upper layers of the Black Sea.
Besides description of the contemporary situation, it was used
to demonstrate the process of anoxic zone formation in the
Black Sea after the Bosphorus appearance.
The obtained results could be used to the description of
nitrogen and sulfur cycles in other natural aquatic ecosystems
where anoxic environment presents or is possible. According to
the hydrophysical processes parametrization the model could be
used for the Arabian Sea, upwelling regions, fjords and etc.:
it is possible to calculate the consequences of anthropogenic
organic matter flux increasing as well as dam building in
river estuaries, inlets and fjords.

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NUMERICAL SIMULATIONS OF THE GLOBAL CLIMATE
AND THE REGIONAL CLIMATE IN CHINA
FOR 18,000 YEARS BEFORE PRESENT


Qian Yun and Qian Yongfu

Department of Atmospheric Sciences
Nanjing University, 210093 Nanjing, P.R. China


In order to precisely evaluate the historical position of the
present environment and predict the trend of climate change in
future, past environmental variations should be necessarily
known. Since CLIMAP (1976) restructed the earth's surface
conditions for 18000 years before present (the last great Ice
Age), a lot of scientists such as Gates, Manabe, and Kutzbach
et. al. have conducted a series of numerical simulations of
the Ice Age climate.

In this paper a regional climate modelling system (RCMS),
which is one-way nested with GCM and includes simple air-sea
and land-air coupling processes, is developed. Then the Ice
Age global climate in summer is first simulated using the GCM.
Meanwhile, the regional climatic variations of the East Asia
and China are emphatically simulated using RCMS under the
background of the Ice Age climate. Impacts on the regional
climate are also analyzed for the large-scale circulation
background and the changes of regional internal factors. The
simulated results show that the Ice Age global mean surface
air temperature was 4.9 F8C lower than today's, and the free
atmosphere temperature both at the lower and the higher
atmosphere also decreased somewhat. Besides, global mean
precipitation was reduced about 0.25 mm/day, and the relative
humidity was about 10 % below today's, while the mean sea
surface atmospheric pressure was higher than that at present.
Under such a varying global background, the Chinese regional
climate manifests relevant changes as well. The temperatures
of the surface and the free atmosphere decrease significantly,
the Chinese mean surface air temperature was reduced by 5.4F8C
or so, and the precipitation (mainly contributed by cumulus
convection) decreased by about 1.3 mm/day which is 5 times the
global mean value. The air pressure system fluctuated within a
larger range than of the global mean. It indicates that there
is a lack of synchronization between global and regional
changes. Either the global background of the large-scale
circulation or the underlying surface conditions themselves
within a limited region would cause the consistence and the
difference between the regional and the global climatic
variations.

A comparison between the simulated results and the limited Ice
Age data obtained from geologic archaeology shows that they
are basically consistent with each other, and the simulated
results by RCMS are more realistic in the RCMS region. Some
climatic features are produced in the East Asia by the RCMS,
while they are not been seen by GCM. The cause is that the
topography and the underlying surface types are much more
meticulous and closer to the reality when the model resolution
is improved, the simulated results are consequently improved.
However, the difference in the physical processes between GCM
and RCMS can also cause the discrepancies in the simulated
results, but both of them have not been distinguished in the
analyses of the results.


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NATION-WIDE RIVER CHEMISTRY: CHEMICAL
COMPOSITIONS AND HISTORICAL TRENDS

J. Zhang

Department of Marine Chemistry, Ocean University of Qingdao
5 Yushan Road, Qingdao 266003, P.R. China

Based on the geochemical studies in last 10 years, the present
work summarizes nation-wide river chemistry features including
the water chemistry and historical trends for nutrient and
trace elements in 10 - 20 large Chinese rivers. Dissolved
trace metals from the large Chinese rivers are still low and
comparable to the large and less disturbed world systems (e.g.
Amazon and Orinoco). Data of high quality analyses are
generally one to two orders of magnitude lower than those
currently reported by the national environmental monitoring
and protection agency. Nutrient elements from Chinese rivers
are similar to or even higher than European and North American
polluted systems (e.g. Loire, Rhine and Rhne etc.) However,
Chinese and European rivers differ in nutrient element ratios.
Examination of the data indicates that the Chinese rivers may
have N/P ratios of 100 - 1000, and the seaward transport of
some nutrient species in large Chinese rivers has been doubled
in last 30-40 years. Clearly, elavated nutrient element
concentrations from Chinese rivers results most likely from
the agricultural and domestic drainages owing to extensive
cultivation (e.g. use of chemical fertilizers) and dense
populations over the watersheds. Trace metal levels in Chinese
rivers remains close to world pristine system, indicating very
limited influence from anthropogenic activities, however.


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TROPICAL DEFORESTATION:
REGIONAL INTERACTIONS OF CLIMATE AND ECOSYSTEM

H. Zhang, A. Henderson-Sellers

Climatic Impacts Centre, Macquarie University
NSW 2109, Australia (email: huqiang@cic.mq.edu.au)

The importance of the tropical ecosystems in maintaining the
local and regional climate regimes in the tropical rainforest
regions is studied using the National Center for Atmospheric
Research Global Climate Model (CCM1-Oz) coupled with the
Biosphere-Atmosphere Transfer Scheme (BATS) and the Bureau of
Meteorology Research Centre (BMRC) GCM coupled with the Bare
Essential for Surface Transfer (BEST) land surface scheme. A
series of landuse change simulations are conducted in which
deforestation is characterized by the surface albedo being
increased; the surface roughness length being reduced and the
soil colour brightened and its texture made coarser. Model
simulation results demonstrate that the tropical rainforest
acts as an important component in the local climate system.
Model simulations of current climate over tropical rainforest
regions (the Amazon Basin, S.E. Asia and tropical Africa) are
analysed. Results show that even though both models
underestimate the high precipitation over the Amazon Basin in
the local wet season, the simulated precipitation over the
Amazon Basin in CCM1-Oz is still large enough that the surface
energy allocation belongs to the "wet" climate regime (the
majority of surface energy is distributed as evaporation).
While the control climate in BMRC GCM is so "dry" that the
surface energy partition has "dry" climate features (the
majority of the surface energy is lost as sensible heat). The
performance of the models' simulation of the current climate
regime has important implications for the simulation of the
climate disturbance due to deforestation. Changes in surface
climate over deforested regions are quite different in the two
model simulations. Results in BMRC GCM show an increase in the
local precipitation, an increase in the surface latent heat
flux and a large decrease in the surface sensible heat flux.
While large reductions of precipitation and evapotranspiration
are seen in the CCM1-Oz simulation. Analyses of the energy
budget and moisture budgets in these two models suggest that
simulation the climatic impacts of tropical deforestation, at
first, depends on the model capacity to simulate the current
climate regimes over these regions. The underestimation of
precipitation over the Amazon Basin in the BMRC GCM has a
significant impact on the land surface energy allocation and
thus affects its simulation of deforestation. Also the
boundary layer processes included in the models influence the
model response to the prescribed disturbance of tropical
deforestation. Over the S.E. Asia and tropical Africa, weaker
but similar changes are simulated compared with those found in
the Amazon Basin. Based upon these model simulations, the
impacts of the local climate changes on the regional ecosystem
are estimated by applying a simplified vegetation scheme. The
preliminary results suggest that the regional climatic changes
due to the deforestation in the Amazon Basin could seriously
impede the regeneration of the secondary rainforest.


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CLIMATE-VEGETATION INTERACTION FOR GLOBAL CHANGE
Guangsheng Zhou and Xinshi Zhang
Institute of Botany, Chinese Academy of Sciences
141 Xizhimenwai Avenue, Beijing, 100044, P.R. China
Global change has received more and more attention for the
decades, CO2 concentration in the atmosphere is increasing at a
much faster rate than has been observed in the historical
record. Understanding how terrestrial ecosystems will response
to CO2-induced global change is necessary for ensuring the
earth suitable for human existence and sustainable development
in future climate.
The study on climate-vegetation interaction is the basis for
the research of terrestrial ecosystems response in global
change, which mainly includes two important parts:
climate-vegetation classification and net primary productivity
(NPP) of natural vegetation. A Chinese climate-vegetation
classification system and a new NPP model will be presented in
this paper.
The potential evapotranspiration (PE) calculated by
Thornthwaite formula or Penman model represents PE from small
evaporated area, it can not reflect a regional energy. It is
not suitable to be used as the index of climate-vegetation
classification. Thus regional potential evapotranspiration
(RPE) should be used in climate-vegetation classification.
According to Bouchet's model and the regional actual
evapotranspiration model established by Guangsheng Zhou and
Xinshi Zhang (1995), RPE will be readily calculated. Two
indexes of climate-vegetation classification system: thermal
index(TI) and surface dry index (SDI) are suggested. This
system is used in China based on the data from 647
meteorological stations. The result showes that this system
can reflect the distribution of vegetation zones in China. A
new NPP model of natural vegetation is also presented, based
on ecophysiological feature of plant and regional
evapotranspiration model. This new NPP model is better than
Chikugo model, especially in arid area. The distribution of
NPP and the changing NPP of natural vegetation under doubled
CO2 condition in China are analysed based on this model.


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NUMERICAL SIMULATION OF THE IMPACT OF BAROCLINE ETC.
ON THE DISPERSION OF THE YANGTZE RIVER DILUTED WATER


J.R. Zhu and H.T. Shen

Institute of Estuarine and Coastal Research, East China Normal
University,
3663 Zhongshan Road (N), Shanghai 200062, P.R. China
The Yangtze River is one of the largest rivers in the world,
it carries an enormous volume of runoff and a huge amount of
sediment emptying into the East China Sea, which significantly
influence the environment of the sea. The interaction between
the land and sea is intense in the offshore area. A three
dimension nonlinear baroclinic shallow water and shelf model
with primitive equations in s-coordinate system was developed
to study the impact of barocline, bottom topography and water
level slope, bottom friction and discharge on the dispersion
of the Yangtze River diluted water. The model equations
include the momentum equations, continuity equation (sea
surface level equation), state equation and salt equation. The
vertical eddy viscosity coefficient is based on the Prandtl's
mixing length concept, varying with the transient vertical
structure of the current. The model equations are discredit in
a completely staggered grid system. The semi-momentum scheme
which is quadratic conservation in used for the nonlinear
terms in the momentum equations. The numerical method is
Alternating Direction Implicit (ADI) scheme. The calculated
domain is the whole continent of the East China Sea.

The results of numerical experiments show that the Yangtze
River diluted water disperse outward with two strands of the
runoff, one is toward NNE, the other is toward SE. This is
caused mainly by the interactions between barocline and bottom
and waterlevel slop. The runoff will disperse only toward SE
forced by the inertial force if the barocline is not
considered. The baroclinic effect plays a dominant role in its
dispersion. The bottom friction has a little influence on it,
which makes it turning left slightly. The discharge does not
determine the basic dispersion pattern, but influences its
extent. The simulation results are basically consistent with
the observation data and can be explained reasonably with the
vorticity equation in which the interaction between barocline
and sloping bottom and waterlevel slop is considered.


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TROPOSPHERIC OZONE BUDGET CALCULATIONS WITH A 3D
TRANSPORT/PHOTOCHEMISTRY MODEL

Peter H. Zimmermann, Paul J. Crutzen

Max-Planck-Institut f1r Chemie, Dept. of Air Chemistry,
PO Box 3060, D-55020 Mainz

The tropospheric ozone budget is controlled by fluxes from the
stratosphere, by photo chemistry, and by deposition at the
earth's surface. For a long time it was generally accepted
that tropospheric ozone entirely derives from the
stratosphere, where about 90% of all atmospheric ozone is
concentrated anyway. Thanks to scientific advances and the use
of numerical models over the last twenty-five years it has
become clear, that considerable amounts of ozone can be
produced photochemically in the troposphere itself.

The photochemistry is strongly controlled by the abundance of
NOx (3D NO + NO2 ) in the air, in a sense that these molecules
catalytically influence the methane oxidation reaction path to
produce ozone. The phenomenon of 'summer smog' with high ozone
concentrations in the urban boundary layer recently has been
drawing increasing attention.

NOx-emissions originate from both natural sources such as
lightning and microbiological activity in soils and from human
activities such as traffic and fossil fuel burning (mainly on
the Northern Hemisphere) and biomass burning (during the dry
season in the tropics). Current statistics assess that about
half of the total global NOx stems from fossil fuel combustion
processes in the industrialized countries mainly over Europe
and North America. But also the developing countries
increasingly contribute to the air pollution.

The 3-dimensional Eulerian grid model MOGUNTIA has been
designed to numerically simulate the transport of trace
constituents by large scale wind, turbulent diffusion, and
deep con vection in the global troposphere and lower
stratosphere, and the most important parts of their
photochemistry in gas and cloud water phase. Under particular
assumptions about stratospheric influx and surface deposition
velocities of ozone as well as about emissions of NOx , the
chemical source and sink terms of tropospheric ozone are
quantified for both present day and preindustrial era in this
study.
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A MODEL OF THE HERBIVORE-DRIVEN BIOME SHIFT
AT THE END OF THE PLEISTOCENE

S.A. Zimov1, V.I. Chuprynin2, A.P. Oreshko2, F.S. Chapin III3,
J.F. Reynolds4,5, and M.C. Chapin3

1North-East Scientific Station, Pacific Institute for
Geography, Far-East
Branch, Russian Academy of Sciences, Republic of Sakha,
Yakutia, Cherskii, Russia

2Pacific Institute of Geography, Far-East Branch, Russian
Academy of Sciences,
7 Radio Street, 690041 Vladivostok, Russia

3Department of Integrative Biology, University of California,
Berkeley, California 94720, USA

4Department of Botany, Duke University, Durham, NC 27708-0340,
USA

5Presenter

Recent experiments and the literature provide consistent


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