Estimation of the aerosol perturbation to the Earth's radiative budget over oceans using POLDER satellite aerosol retrievals

POLDER satellite retrievals of aerosol properties over oceans are used to e stimate a global-mean clear-sky aerosol shortwave flux perturbation of orde r -5 to -6 Wm(-2). Uncertainties due to aerosol absorption and POLDER cloud screening algorithm are quantified. In order to bound the radiative forcin g by anthropogenic aerosols, we attempt to remove the contribution of backg round aerosols from these estimates and present all-sky aerosol radiative e ffects for three regions and two methods. The results are sensitive to the thresholds used to define the background conditions.