Abstract ID: 566

Simulating the direct effect of biomass burning aerosols on the radiative budget, surface fluxes and hydrological cycle on Amazon basin.

Biomass burning aerosols have strong interaction with solar radiation through absorption and scattering. This interaction reduces the net radiation on surface available for the surface heat and latent fluxes and causes a net warming of atmosphere laden aerosols layers. The net effect is a cooling below and warming above inducing a more stable atmosphere and convective inhibition. During the dry season in South America, the spatial variability of the aerosols over Amazon Basin shows that large areas of 3 - 5 millions of km2 are affected by the high aerosols concentrations. In this work, we present model simulations of this effect on the radiation surface budget, surface fluxes, convective inhibition and precipitation associated to the presence of biomass burning smoke. The model system CATT-BRAMS is used to simulate this effect through a radiation parameterization which takes the interaction between aerosol particles and short and long wave radiation. This parameterization uses the rapid two-stream approximation (Toon, et al., 1989) and an aerosol scattering and absorption calculated with the Mie code for stratified spheres (Toon and Ackerman, 1981). For smoke aerosols, a dynamic model, derived from three years of optical properties retrievals from some of the Amazonian AERONET sites measurements, is used (Procópio et al., 2003). Two simulations for the 2002 dry season were performed including or not this effect on the model governing equations. We show that the aerosol radiative effect alone accounts for a reduction up to 30% over 3-months accumulated rainfall on Rôndonia area.

Session:  Feedbacks to Climate - Emissions of natural and biomass burning particulates from vegetation and their effects on ecosystems and climate.

Presentation Type:  Poster