Physical processes influencing the Asian climate due to the black carbon emissions over China and India

Current and expected future aerosol emission changes are particularly strong in East and South Asia, where high population densities imply high potential climate risk. Hence, there is an urgent need for improved knowledge about the near-term influences of changes in aerosol emissions. Here we have developed a set of Systematic Regional Aerosol Perturbations (SyRAP) using the reduced complexity climate model FORTE 2.0 to explore the effects of aerosol-driven climate change. Results show that the increased Black Carbon(BC) concentrations over China and India lead to decreased local surface Temperature (Ts) and precipitation, with seasonal differences in the spatial distribution. Chinese (Indian) BC emissions also impact on Indian (Chinese) climate in specific seasons. The changes of shortwave radiation (SW) dominate the surface cooling and the lower tropospheric warming due to the absorption of BC. The reductions of column-intergrated diabatic cooling lead to the decreased local precipitation, while the changes in atmospheric circulation play an opposite role (weakened EAWM, enhanced EASM and ISM). The horizontal/vertical distributions of air temperature anomalies can induce the changes in cloud cover and atmospheric circulation, which further impact on the radiation flux and precipitation. Additionally, the increased surface albedo in winter is helpful to decrease Ts and precipitation.