HR: 1340h
AN: A33E-1648    [Abstracts]
TI: Investigating smoke's influence on primary production throughout the Amazon
AU: * Flanner, M G
EM: mflanner@ucar.edu
AF: National Center for Atmospheric Research, Advanced Studies Program, 1850 Table Mesa Dr., Boulder, CO 80305, United States
AU: Mahowald, N M
EM: nmm63@cornell.edu
AF: Cornell University, Department of Earth and Atmospheric Sciences, 2140 Snee Hall, Ithaca, NY 14853, United States
AU: Zender, C S
EM: zender@uci.edu
AF: University of California - Irvine, Earth System Science Department, Croul Hall, Irvine, CA 92697-3100, United States
AU: Randerson, J T
EM: jranders@uci.edu
AF: University of California - Irvine, Earth System Science Department, Croul Hall, Irvine, CA 92697-3100, United States
AU: Tosca, M G
EM: mtosca@uci.edu
AF: University of California - Irvine, Earth System Science Department, Croul Hall, Irvine, CA 92697-3100, United States
AB: Smoke from annual burning in the Amazon causes large reduction in surface insolation and increases the diffuse fraction of photosynthetically-active radiation (PAR). These effects have competing influence on gross primary production (GPP). Recent studies indicate that the sign of net influence depends on aerosol optical depth, but the magnitude of smoke's effect on continental-scale carbon cycling is very poorly constrained and may constitute an important term of fire's net impact on carbon storage. To investigate widespread effects of Amazon smoke on surface radiation properties, we apply a version of the NCAR Community Atmosphere Model with prognostic aerosol transport, driven with re-analysis winds. Carbon aerosol emissions are derived from the Global Fire Emissions Database (GFED). We use AERONET observations to identify model biases in aerosol optical depth, single-scatter albedo, and surface radiative forcing, and prescribe new aerosol optical properties based on field observations to improve model agreement with AERONET data. Finally, we quantify a potential range of smoke-induced change in large-scale GPP based on: 1) ground measurements of GPP in the Amazon as a function of aerosol optical depth and diffuse fraction of PAR, and 2) empirical functions of ecosystem-scale photosynthesis rates currently employed in models such as the Community Land Model (CLM).
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
DE: 0360 Radiation: transmission and scattering
DE: 0428 Carbon cycling (4806)
DE: 9360 South America
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting