Towards a Large-Scale Aquatic Carbon Model for the Amazon Basin
Erica
Akiko
Howard, University of Wisconsin - Madison, Center for Sustainability & the Global Environment, eahoward@wisc.edu
(Presenting)
Michael
T.
Coe, University of Wisconsin - Madison, Center for Sustainability & the Global Environment, mtcoe@wisc.edu
Jonathan
A.
Foley, University of Wisconsin - Madison, Center for Sustainability & the Global Environment, jfoley@wisc.edu
Marcos
Heil
Costa, Universidade Federal de Viçosa, mhcosta@ufv.br
The work of Richey et al. (2002) has focused attention on the importance of carbon dioxide efflux to the atmosphere from waters of the Amazon basin. We are taking steps toward quantifying this flux on the scale of the whole basin. Our approach uses a combination of an ecosystem land surface model (IBIS – Foley et al. 1996, Kucharik et al. 2000), a hydrological routing model (HYDRA – Coe 2000, Coe et al. 2002), and a new aquatic carbon processing module that we are incorporating into HYDRA.
Here, we describe the current state of this C model and our future plans for development. We drive the model with IBIS-derived estimates of surface and groundwater from the terra firme, várzea, and igapó, and with empirically-derived estimates of C inputs. To allow for seasonal fluctuations in the aquatic-terrestrial transition zone, for each timestep HYDRA simulates the volume of water contained in each of four chemically-distinct zones in each grid cell: pelagic (open water), littoral (near-shore), floodable lowland, and terra firme (upland). With this information the model simulates the dynamics among six different pools of aquatic C: autotrophs, coarse particulate organic carbon (CPOC), fine particulate organic carbon (FPOC), dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and sediment. Water and C are explicitly advected to downstream grid cells. The amount of CO2 efflux from the water surface is calculated for each grid cell, in each timestep. This model is being calibrated with empirical data from the CAMREX project and LBA sources. As the model is developed, it will eventually be driven with a combination of annual climate datasets, soils and topographical data, and remote-sensing-based maps of wetland extent.