A Look at Amazon Basin Seasonal Dynamics with the Biophysical ...

Causes and Mechanisms of Interannual CO2-flux Variability in South American Tropics.Shevlaikoava E(1), Hurtt GC(2), Pacala SW(1), Fearon M(2), Malyshev S(1), Moore B(2), Nobre C(3)(1) Department of Ecology and Evolutionary Biology, Princeton University, Princeton,NJ 08544-1003.(2) Institute for the Study of Earth Oceans and Space, University of New Hampshire,Durham, NH 03824 USA.(3) CPTECInterannual variability in Amazonian terrestrial ecosystems functioning during the pasttwo decades is examined in order to estimate the range of variations in biogenic sourcesand sinks of CO 2 as well as the changes in the biophysical conditions affecting regionalclimate. The primary tools used in this analysis are the Ecosystem Demography (ED)family of models. These models simulate both the fast (hours) and long (centuries)timescales of carbon and water fluxes and ecosystem dynamics and provide importantbiophysical parameters for climate studies of the region. Run off-line, the models can bedriven by climate data from the ECMWF and NCEP reanalysis products. In thispresentation, we begin by exploring sensitivities of tropical ecosystem photosyntheticproduction and respiration to variation in temperature, precipitation, atmospherichumidity, available radiation and wind conditions in the 80s and 90s. The interannualvariability in carbon fluxes due to these effects will be compared to other availableestimates. Future studies with these models are being designed to sequentially addadditional effects needed such as land use change and fire that are needed forcomprehensive carbon flux estimates.