报告题目：Impacts of Middle East dust aerosols on Indian summer monsoon

　　报 告 人：Dr. Qinjian Jin (靳秦建)

　　单   位：Massachusetts Institute of Technology, The University of Texas at Austin

　　时   间：2017年4月10日上午10:30

　　地   点：大气所40号楼319会议室

　　摘  要：Indian summer monsoon (ISM) affect the lives of more than one sixth of the world’s population. Monsoonal rainfall is influenced by multiple factors, including sea surface temperature, land–atmosphere interactions, aerosols, and so on. Several hypotheses have been proposed addressing the aerosols’ impacts on the ISM. “solar dimming” and “elevated heat pump” effects focus on the local anthropogenic and dust aerosols in India and the Tibetan Plateau. Here, we present the impacts of dust aerosols in the Middle East on the ISM system. Various types of datasets and numerical simulations (i.e., WRF-Chem) were used. Observational data reveals a significant correlation between the ISM rainfall in Central and East India and aerosol optical depth over the Arabian Sea and the Arabian Peninsula. Multi-variate empirical orthogonal function analysis demonstrated a coupled relationship between high aerosol loadings, 123the troposphere heating over the Middle East, especially over the Arabian Sea and the Iran Plateau, which are associated with a low pressure center and an enhanced southwesterly monsoon circulation. The enhanced circulation can transport more water vapor from the Arabian Sea to the Indian subcontinent, consequently resulting in more ISM rainfall. These features of aerosols, atmospheric heating, circulations, and ISM rainfall are reproduced in WRF-Chem ensemble simulations. The timescale of the dust impacts on the ISM is about two weeks based on cross correlation analysis in both observation data and model simulations. Further model simulations show that the magnitude of the enhanced ISM rainfall by Middle East dust is similar to that induced by “elevated heat pump” effect. Finally, model illustrates that the ISM rainfall response to dust aerosols is highly sensitive to dust aerosols’ absorptive properties (i.e., more absorptive, more rainfall).