HR: 09:30h
AN: B41C-06    [Abstracts]
TI: Mesoscale Circulations and Atmospheric CO2 Variations in the Tapajos Region, Para, Brazil
AU: * Lu, L
EM: lixin@atmos.colostate.edu
AF: Department of Atmospheric Science, Colorado State University, 200 West Lake Street, Fort Collins, CO 80523 United States
AU: Denning, S A
EM: denning@atmos.colostate.edu
AF: Department of Atmospheric Science, Colorado State University, 200 West Lake Street, Fort Collins, CO 80523 United States
AU: Silva-Dias, M A
EM: mafdsdia@master.iag.usp.br
AF: Department of Atmospheric Sciences, University of Sao Paulo, USP, Sao Paulo, 99999 Brazil
AU: Silva-Dias, P d
EM: pldsdias@master.iag.usp.br
AF: Department of Atmospheric Sciences, University of Sao Paulo, USP, Sao Paulo, 99999 Brazil
AU: Longo, M
EM: marcos@master.iag.usp.br
AF: Department of Atmospheric Sciences, University of Sao Paulo, USP, Sao Paulo, 99999 Brazil
AU: Freitas, S R
EM: sfreitas@cptec.inpe.br
AF: Department of Atmospheric Sciences, University of Sao Paulo, USP, Sao Paulo, 99999 Brazil
AU: Saatchi, S
EM: saatchi@congo.jpl.nasa.gov
AF: NASA Jet Propulsion Laboratory, Pasadena, Pasadena, CA 99999 United States
AB: We have investigated mesoscale variations of atmospheric CO2 over a heterogeneous landscape of forests, pastures, and large rivers during the Santar"Ým Mesoscale Campaign (SMC) of August 2001. The variations of atmospheric CO2 concentration were simulated using the Colorado State University (CSU) Regional Atmospheric Modeling System (RAMS) with 4-level nested grids that included a 1-km finest grid centered on the Flona Tapaj"rs. Surface fluxes of CO2 were prescribed in the model using idealized diurnal cycles over forest and pasture vegetation derived from flux tower observations, and over surface water using a value suggested by in situ measurements in the Amazon River. Heterogeneous vegetation types were derived from the 1-km International Geosphere-Biosphere Programme (IGBP) land-cover dataset version 2.0. Our simulation ran from the 1st through the 15th of August 2001, which was concurrent with the SMC. Evaluation against flux tower observations and the SMC field measurements shows that, in many respects, the model captures observed meteorological variables and CO2 concentrations reasonably well. The results also demonstrate that the local topography, differences in roughness length between water and land, the "T" shape juxtaposition of Amazon and Tapaj"rs Rivers, and the resulting horizontal and vertical wind shears, all facilitated the generation of local mesoscale circulations. Possible mechanisms producing a lower level convergence line near the east bank of the Tapaj"rs River during strong trade-wind conditions are also explored. Our modeling study is helping us to understand observed patterns of CO2 fluxes and concentration distribution obtained from flux towers and light aircraft.
DE: 4806 Carbon cycling
DE: 4255 Numerical modeling
DE: 1615 Biogeochemical processes (4805)
DE: 0315 Biosphere/atmosphere interactions
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting