South Asian Summer Monsoon Precipitation is Sensitive to Southern
Hemisphere Subtropical Radiation Changes
Abstract
We study the sensitivity of South Asian Summer Monsoon (SASM)
precipitation to Southern Hemisphere (SH) subtropical Absorbed Solar
Radiation (ASR) changes using Community Earth System Model 2
simulations. Reducing positive ASR biases over the SH subtropics impacts
SASM, and is sensitive to the ocean basin where changes are imposed.
Radiation changes over the SH subtropical Indian Ocean (IO) shifts
rainfall over the equatorial IO northward causing 1-2 mm/day drying
south of equator, changes over the SH subtropical Pacific increases
precipitation over northern continental regions by 1-2 mm/day, and
changes over the SH subtropical Atlantic have little effect on SASM
precipitation. Radiation changes over the subtropical Pacific impacts
the SASM through zonal circulation changes, while changes over the IO
modify meridional circulation to bring about changes in precipitation
over northern IO. Our findings suggest that reducing SH subtropical
radiation biases in climate models may also reduce SASM precipitation
biases.