Effects of biomass burning in Amazonia on climate: A numerical experiment with a statistical-dynamical model

Chou and Suarez's solar and infrared radiation models are incorporated in a statistical‐dynamical model with biosphere and atmosphere interaction in order to study the climatic effects due to biomass burning in Amazonian forest. In the control experiment the mean annual zonally averaged climate is well simulated by the model when compared with observed data. Biomass burning plays an important role on the earth's radiative balance and climate through the release of large amounts of greenhouse gases and aerosols in the atmosphere and the alteration of the land surface characteristics. For investigating the relative importance of these changes five experiments are performed: (1) degradation of the surface, (2) change in the smoke aerosols concentration, (3) change in the CO2 concentration, (4) change in CH4 concentration, and (5) all the changes together. The results show that biomass burning in Amazonian forest causes a reduction in the absorbed solar radiation and net radiation fluxes at the surface in the perturbed region and an increase in the air surface temperature and the net thermal infrared radiation flux at the surface. Also there is a decrease in the latent and sensible heat fluxes, evapotranspiration and precipitation compared to the control case. In general, the greater changes in the radiative balance and climate are due mainly to the changes in the land surface characteristics, followed by those caused by the large amounts of smoke aerosols released in the atmosphere. The changes due to the greenhouse gases CO2 and CH4 are small.