Satellite-based analysis of top of atmosphere shortwave radiative forcing trend induced by biomass burning aerosols over South-Eastern Atlantic

This study investigates long-term changes in the shortwave direct aerosol radiative effect (DARE) at the top of the atmosphere (TOA) induced by biomass burning aerosol (BBA) transported from southern Africa to the south-eastern Atlantic (SEA) stratocumulus region during extended fire seasons. The evolution since 2002 of aerosol, cloud properties, and TOA shortwave outgoing radiation from advanced passive satellite sensors are presented, as well as the observational trend in clear-sky DARE_clr and the retrieval trend in all-sky DARE_all. Supplemented by chemical transport model simulations, we estimate that DARE_clr has become more negative (−0.09 ± 0.06 W m⁻² yr⁻¹) due to increased aerosol presence in SEA. Meanwhile, DARE_all has become more positive ( + 0.04 ± 0.15 W m⁻² yr⁻¹) due to aerosols in cloudy sky regions. This study reveals satellite capabilities in capturing complex BBA-cloud-solar radiation interactions for accurate radiative forcing estimates and projections.