Shortwave direct radiative forcing of biomass burning aerosols estimated using VIRS and CERES data

Using collocated data from the Visible Infrared Scanner (VIRS) and the Clouds and the Earth's Radiant Energy Budget Scanner (CERES) from the Tropical Rainfall Measuring (TRMM) satellite, observational estimates of the instantaneous Shortwave Aerosol Radiative Forcing (SWARF) of smoke aerosols at the top-of-atmosphere (TOA) are obtained for four days in May 1998 during a biomass-burning episode in Central America. The detection of smoke aerosols is demonstrated using VIRS imagery. Assuming a single scattering albedo (omega(o)) of 0.86 (at 0.63 mu m) that is representative of absorbing aerosols, smoke optical thickness (tau(0.63)) is retrieved over ocean areas. The average tau(0.63) for these four days was 1.2 corresponding to a SWARF value of -68 Wm(-2) The SWARF changes from -24 to -99 Wm(-2) as tau(0.63) changes from 0.2 to 2.2. Global observational estimates of biomass burning aerosol radiative forcing can be obtained by combining data sets from TRMM and Terra satellites.