Satellite Remote Sensing of Shortwave Aerosol Direct Effect over Global Oceans

Using the Clouds and the Earth's Radiant Energy System (CERES) Single Satellite Footprint (SSF) product from Terra that merges the Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol and cloud information with CERES top of atmosphere radiative fluxes, we examine the short wave aerosol direct radiative effect (SWARF) over cloud free global oceans. We also present strategies for converting the satellite-derived instantaneous values to diurnally averaged estimates. Since the CERES has a large footprint, sample biases are possible and we estimate this effect using different techniques. We also discuss the uncertainties in this approach and compare our results with other studies that use satellite-derived aerosol optical thickness but require radiative transfer calculations to estimate the radiative fluxes. Our study requires no radiative transfer calculations to convert the retrieved aerosol optical thickness to SWARF values and is an independent measurement-based assessment of cloud-free aerosol radiative effect.