El Nino次年夏季东亚降水异常特征并不稳定，不同El Nino事件存在较大的差异。本项目拟以1997/98和2015/16两个极端El Nino事件为典型个例，结合更多的El Nino事件，归纳总结El Nino次年夏季东亚降水异常的多样性特征；研究不同类型El Nino在其演变不同阶段对东亚夏季降水异常影响的过程与途径；揭示El Nino与中高纬大气异常信号的主要配置关系，弄清热带与热带外信号影响东亚夏季降水异常的动力过程及其相对贡献；揭示不同尺度气候背景态对El Nino次年夏季东亚降水年际异常的贡献及其作用机理。综合El Nino多样性与演变特征、El Nino与中高纬大气异常信号配置关系和不同尺度气候背景态三个方面的作用，阐明El Nino次年夏季东亚降水异常多样性的形成机理，找到关键区域、关键因子和关键动力与物理过程。研究所得成果将加深对东亚夏季降水异常机制的认识和理解。

The characteristics of East Asian summer precipitation anomalies (EASPA) in El Nino decaying summer are not always consistent with each other among different El Nino events, demonstrating pretty large discrepancies. With enough El Nino events, especially the two extreme El Nino events of 1997/98 and 2015/2016, this project will represent and summarize the EASPA diversity characteristics, and illustrate the mechanism from the aspects of El Nino diversity and evolution, configuration of El Nino and atmospheric anomalies in the mid-high latitudes, and background climate states at different time scales. Specifically, the impacts of different types of El Nino on the EASPA at different El Nino stages will be investigated; the configurations of El Nino and atmospheric anomalies in the mid-high latitudes will be identified, and accordingly, dynamical processes of the tropical and extratropical forcing to the EASPA will be discovered, so are their relative roles; contributions of background climate states at different time scales to the interannual EASPA as well as their influence mechanisms will be revealed. The outcome of this project will improve the understanding of EASPA mechanism, and provide strong scientific and theoretical foundations for the accurate seasonal prediction of China summer precipitation anomalies.