Assessing Aerosol Radiative Forcing and Atmospheric Absorption Over South Asia: A Multi‐Model Intercomparison Study

Abstract This study investigates effective radiative forcing (ERF) and atmospheric absorption due to aerosols over South Asia, focusing on changes in emissions from the pre‐industrial period to the present day. Utilizing four global climate models (GCMs), CAM5, CAM6, ECHAM6, and NICAM‐SPRINTARS, alongside a common regional emission inventory (SMoG‐India‐v1) and global Community Emissions Data System (CEDS) for emissions outside India, we assess the perturbations in shortwave (SW), longwave (LW), and net radiative fluxes resulting from aerosol emissions. Our analysis reveals a multi‐model mean aerosol net ERF of −1.66 W/m 2 at the top of atmosphere (TOA), indicating significant cooling driven by a substantial negative SW ERF (−4.59 W/m 2 ) dominated by aerosol‐cloud interactions (ERF ACI ), partially offset by net positive LW ERF (+2.93 W/m 2 ). At the surface, the net ERF indicates pronounced cooling of approximately −10.95 W/m 2 , driven by both SW aerosol‐radiation interaction (ERF ARI ; −8.31 W/m 2 ) and SW ERF ACI (−5.40 W/m 2 ), with a positive LW ERF (+2.65 W/m 2 ). Atmospheric absorption, the difference between ERF at TOA and the surface, shows a net absorption of +9.29 W/m 2 , dominated by SW absorption from direct aerosol‐radiation interactions (SW Atm.Abs. ARI ), contributing +8.99 W/m 2 , with LW absorption from aerosol‐cloud interactions (LW Atm.Abs. ACI ) adding +1.83 W/m 2 . These findings highlight the dominant role of aerosol‐cloud interactions in cooling at both TOA and the surface and the significant contribution of direct aerosol interactions to atmospheric absorption over the Indian region. This underscores the need to consider both aerosol effects in climate models to improve regional climate predictions and support effective mitigation and adaptation strategies.