Modeling Study of the Effect of Anthropogenic Aerosols on Late Spring Drought in South China

In this study, the mechanisms underlying the decadal variability of late spring precipitation in South China are investigated by using the latest Community Earth System Model version 1 (CESM1). We aim to unravel the effects of different climate forcing agents such as aerosols and greenhouse gases (GHGs) on the decadal variation of precipitation, based on transient experiments from pre-industry (for year 1850) to present-day (for year 2000). Our results reveal that: (1) CESM1 can reproduce the climatological features of atmospheric circulation and precipitation for the late spring in South China; (2) only simulations including the forcing of anthropogenic aerosols can reproduce the observed decreasing trend of late spring precipitation from 1950-2000 in South China; (3) aerosols affect the decadal change of precipitation mainly by altering the large-scale atmospheric circulation, and to a less extent by increasing the lower-tropospheric stability to inhibit the convective precipitation; and (4) in comparison, other climate forcing agents such as GHGs have much smaller effects on the decadal change of spring precipitation in South China.