The influences of mesoscale circulations and River CO2 effluxes on regional carbon balance in the Tapajos Region, Para, Brazil.
Lixin
Lu, Department of Atmospheric Science, Colorado State University, lixin@atmos.colostate.edu
(Presenting)
Scott
A.
Denning, Department of Atmospheric Science, Colorado State University, denning@atmos.colostate.edu
Maria Assução
Faus da
Silva Dias, CPTEC & University of Sao Paulo, assuncao@cptec.inpe.br
Pedro
Leite
Silva Dias, CPTEC & University of Sao Paulo, pldsdias@master.iag.usp.br
Marcos
Longo, University of Sao Paulo, marcos@master.iag.usp.br
Saulo
Ribeiro de
Freitas, University of Sao Paulo, sfreitas@cptec.inpe.br
Jeffrey
E.
Richey, university of Washington, jrichey@u.washington.edu
Sassan
Saatchi, NASA JPL, saatchi@congo.jpl.nasa.gov
We have investigated mesoscale variations of atmospheric co2 over a
heterogeneous landscape of forests, pastures, and large rivers during
Santarem Mesoscale Campaign (SMC) during August 2001. We simulated the variations of surface fluxes and atmospheric concentration of co2 using the CSU Regional Atmospheric Modeling System (RAMS) on a 4-level nested grids which including a 1-km finest grid centered on the Flona Tapajos. Surface fluxes of co2 were prescribed in the model using idealized diurnal cycles over forest and pasture vegetation, 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 1 through 15 August 2001, which was concurrent with our SMC. The model evaluation against flux tower observations and SMC field measurements shows that, in many aspects, our model is doing good job of simulating observed meteorological variables and CO2 concentrations. The results also demonstrated that the local topography and landsacape features, along with the differences in roughness length between water and land, the "T" shape juxtaposition of Amazon and Tapajos Rivers, and the resulting horizontal and vertical wind shears, all facilited the generation of local mesoscale circulations. The mechanisms producing the lower level convergence line on the east bank of Tapajos River during the strong trade-wind days is also explored. Meanwhile, we investigated the effects of surface water co2 efluxes on the regional carbon balance. The simulations with and without specifying co2 fluxes from the rivers and inundated land were performed. The result demonstrated that surface water co2 fluxes modifies simulated co2 concentrations, especially at night. Our modeling study not only help us to understand the current debate on the role of Amazon as carbon sources and sinks, but also help us to evaluate and identify the possible sources and systematic bias of aircraft and tower measurements.
Submetido por Lixin Lu em 18-MAR-2004
Tema Científico do LBA: CD (Armazenamento e Trocas de Carbono)