An exploration of the aerosol indirect effects in East Asia using a regional climate model

In this study, the aerosol direct, semi-direct and indirect effects on the East Asia climate are investigated using the International Center for Theoretical Physics Regional Climate Model v. 4 (RegCM4.1.1), by focusing on the East Asian Summer Monsoon temperature and precipitation. The externally mixed aerosols, including sulfate (SO42-), black carbon and organic carbon, reduced the solar flux reaching the surface directly by scattering solar radiation, and indirectly by increasing the cloud droplet concentration and cloud liquid water path over East China. The combined aerosol effects (direct and indirect) decreased the temperature on the continent and increased it over the oceans, leading to the reduction of rainfall in the central regions of China and an enhancement of rainfall in the adjacent ocean regions.