2020 Articles

South Asian summer monsoon response to aerosol-forced sea surface temperatures

Li, Xiaoqiong; Ting, Mingfang; You, Yujia; Lee, Dong Eun; Westervelt, Daniel M.; Ming, Yi

Climate models suggest that anthropogenic aerosol‐induced drying dominates the historicalrainfall changes over the heavily populated South Asian monsoon region. The regional response dependson both the aerosol fast radiative effect and the slow process through sea surface temperature (SST)cooling. Two atmospheric general circulation models, NCAR‐CAM5 and GFDL‐AM3, are used to investigatethe monsoon response to prescribed aerosol‐forced SSTs. The total SST is separated into uniform cooling anda spatially varying component characterized by interhemispheric asymmetry. The monsoon rainfall ispredominantly controlled by the nonuniform SSTs, in the local Indian Ocean, South, and East China Seas(IO‐CSs). The reduced meridional SST gradient in the IO‐ CSs leads to weakened monsoon circulation,which drives a north‐south dipole rainfall change. The latitudinal location of the dipole shows modeldependence due to differences in local SSTs and their meridional gradient, which determines the latitudinallocation of the meridional overturning circulation responses.