Effect of aerosol changes on regional climate in East Asia

This study investigates the effect of aerosol changes on regional climate in East Asia. Especially, we focus on the recent decreasing trend of aerosol concentrations in China from 2011 to 2018. We conduct climate sensitivity simulations using the Community Earth System Model (CESM) atmospheric general circulation model (AGCM) with observed monthly sea surface temperatures (SST) and sea ice concentrations (SIC) and coupled general circulation model (CGCM) with its own predicted SST and SIC from the coupled ocean and sea ice models. We prescribe the observed monthly aerosol optical depths from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Terra and Aqua satellite for the base simulations and period-averaged monthly aerosol optical depths for the sensitivity simulations. Comparisons of 50 ensemble averages between the base and sensitivity simulations for the AGCM and CGCM models show that the decreasing aerosols in East Asia warm up the region due to increased net shortwave radiation. We also found that the CGCM simulations show much stronger and more extensive warming in East Asia due to decreasing aerosols than the AGCM simulations, implying the importance of the aerosol-ocean-atmosphere feedback.