All-Sky Direct Aerosol Radiative Effects Estimated from Integrated A-Train Satellite Measurements

Abstract. Improved satellite-derived observations of the Direct Aerosol Radiative Effects (DARE) remain essential to reduce the uncertainty in the impact of aerosol on solar radiation. We develop a framework to compute DARE at the top of the Earth’s atmosphere, in the short-wave part of the electromagnetic spectrum and in all-sky conditions along the track of the A-Train constellation of satellites. We use combined state-of-the-art aerosol and cloud properties from satellite sensors Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and Moderate Resolution Imaging Spectroradiometer (MODIS). We also use a global reanalysis from the Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA-2) to provide vertical distribution of aerosol properties and atmospheric conditions. Diurnal mean satellite DARE values range from -25 (cooling) to 40 W⋅m^-2 (warming) over the Southeast Atlantic during three days from the NASA ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) aircraft campaign. These three days also show agreement between our satellite DARE and co-located airborne Solar Spectral Flux Radiometer (SSFR) measurements. This paper constitutes the first step before applying our algorithm to many more years of combined satellite and model data over many regions of the world. The goal is to ultimately assess the order of importance of atmospheric parameters in the calculation of DARE for specific aerosol and cloud regimes. This will inform future missions where, when and how accurately the retrievals should be performed to reduce all-sky DARE uncertainties.