Direct and Semi-Direct Aerosol Effects: a Modeled Study for Biomass Burning Aerosol Radiative Forcing in the Amazon Region

The effect of clouds on aerosol radiative forcing is examined by means of simulations considering the presence of a cloud layer above a homogeneous biomass burning aerosol layer. The forcings were calculated considering that aerosols can reduce cloud formation, the semi-direct effect. A comparison of these results with the forcings calculated for clear sky condition shows that aerosol radiative forcing can be significantly altered by the semi-direct effect, suggesting that this should be considerate in further studies of regional climate change.