Dust Radiative Effects Over Global Oceans

Using one year of moderate resolution imaging spectroradiometer (MODIS) and clouds and the Earth's radiant energy system (CERES) data, we provide a satellite-based assessment of top-of-atmosphere (TOA) cloud-free shortwave and longwave dust radiative effects over global oceans from the Terra satellite. Over global cloud-free oceans, the dust net radiative effect is -0.7 plusmn0.2 W middotm -2 , and the TOA dust shortwave radiative effect (SWRE) dominates the longwave radiative effect (LWRE). Globally, the annual mean dust contribution to the total MODIS level 2 aerosol optical thickness (AOT, at 550 nm) is about 30% with a dust SWRE of -0.7 plusmn0.2 W middotm -2 and LWRE of 0.03 plusmn0.02 W middotm -2 . Averaged over all seasons, the cloud-free diurnal mean dust radiative efficiency is -33 plusmn5 W middotm -2 middottau -1 , and there is a remarkable linear relationship between the CERES SWRE and the MODIS AOT. This is the first satellite-based assessment of dust net radiative effect over the global oceans and will serve as a useful constraint for numerical modeling analysis.