Smoke aerosol optical thickness retrievals and estimation of direct radiative forcing using GOES-8 imager

Each year more than 100 million tons of smoke aerosols are released into the atmosphere from biomass burning out of which 80% is in the tropical regions. These sub-micron smoke particles composed primarily of oxidized organic materials are efficient in scattering and absorbing sunlight. There are two major radiative effects of biomass burning aerosols. The first called the "direct" radiative effect refers to the scattering and absorption of incoming solar radiation by smoke aerosols. The second effect called the "indirect" radiative effect refers to the interaction of smoke aerosols with clouds. One of the key parameters that must be carefully retrieved and studied is smoke aerosol optical thickness that serves as a measure of aerosol loading in the atmosphere. Currently several ground-based sites from the Aerosol Robotic Network (AERONET) program are in operation to obtain aerosol optical thickness. However, satellite retrievals of aerosol optical thickness are currently limited to polar orbiting satellites. In this study, using high temporal resolution geostationary imager data, smoke aerosols are first identified. Vicarious calibration procedures are used to correct for the degradation in signal response of the GOES-8 imager. Smoke aerosol optical thickness is retrieved on a regional basis and compared against point measurements made from the AERONET stations. Finally, using the satellite retrieved aerosol optical thickness, direct radiative forcing of smoke aerosols are estimated using radiative transfer calculations.