In this paper we asses the biomass burning for a period of 5 years over Amazonian regions in South America. We use all available (2000 through 2005) space and time coincident multi-sensor data from MODIS, MISR and CERES onboard Terra Satellite for estimating Top of the Atmosphere (TOA) shortwave aerosol radiative forcing (SWARF). Our results show an increase in diurnally averaged SWARF from -5.2 Wm^-2 to -9.3 Wm^-2 corresponding to an increase in MISR Aerosol Optical Thickness (AOT) of 0.18 to 0.36. The 5 year mean diurnally averaged SWARF is -7.6 Wm^-2 and an estimated uncertainty of ± 1.4 Wm^-2. The estimated mean TOA aerosol radiative forcing efficiency is -44.2 Wm^-2t^-1. To underpin the association of increased forcing values we investigate the fire activity in the study region using MODIS fire product and find an increase in fire activity from 2000 to 2005. MISR also offers AOT information as a function of particle sizes. We analyze this data to confirm that biomass burning primarily comprises of organic particulates that belong to small mode aerosol sizes and that SWARF is mainly caused by this particles during the burning season. Our analysis shows that 66% of contribution to total AOT comes from small mode aerosols (<0.35 μm) while 16% and 18% is contributed by medium (0.35 – 0.7 μm) and large mode (>0.7 μm) aerosols respectively. This is the first multi-year assessment of SWARF for biomass burning aerosols using satellite observations alone and should serve as a useful constraint for numerical modeling simulations that estimate SWARF.