Volcanic Aerosol Forcing Suppresses Tropical African Rainfall: Mechanisms and Modulation by a Warmer Climate

In this study, we use a 30-member initial-condition large ensemble of the fully coupled CESM1.2.2/CAM5 to quantify the spatial distribution, intensity, and seasonal evolution of precipitation and runoff anomalies following a Tambora-size eruption prescribed from the IVI2 volcanic aerosol reconstruction. We focus on three major basins along the ITCZ migration corridor—the Niger (West Africa), Congo (Central Africa), and Ethiopian-Nile (East Africa) basins—and diagnose the response in their dominant wet seasons (MJJAS for West/East Africa and NDJFM for Central Africa). We further compare responses under a preindustrial (1850) background and a warmed RCP4.5 background climate.