气候变化及其造成的灾害倍受科学界和决策者的高度关注。华西秋雨作为我国西部地区秋季出现的一种高影响气候现象，严重威胁社会经济和生命财产安全。因此，深入研究全球变暖背景下华西秋雨的变化规律和机理具有重要的科学价值和实际应用价值。然而，以往关于华西秋雨的研究大都集中于季节尺度和年际尺度上，对华西秋雨的长期变化与机理鲜有涉及，极大地限制了对华西秋雨变化规律和机理的理解。基于此，本项目以华西秋雨长期变化为出发点，以变化事实-过程机理-未来预估为研究思路，通过观测资料和模式资料分析，明晰当前全球变暖背景下华西秋雨的变化特征，探讨极区气候系统（如，南极涛动、北极涛动、南极海冰、北极海冰）变化对华西秋雨年代际变化的作用和相应的物理机制；采用全球模式和区域模式动力降尺度相结合，综合预估华西秋雨的未来演变规律，以期为理解华西秋雨长期变化与机理提供关键性新认识，为我国适应气候变化和防灾减灾提供科学支撑。

Climate change and resultant disasters are highly concerned by the scientific community and decision makers. As a high-impact climate phenomenon, autumn rain in West China poses a serious threat to the social economy and the safety of life and property. Therefore, study on the change of autumn rain in West China and the related physical mechanism in the context of global warming owes important scientific value and application value. However, previous studies on the autumn rain in West China focused mainly on the seasonal and interannual time scales, and paid little attention to its secular change and associated physical mechanism, which greatly constrains our understanding of the evolution characteristic of autumn rain in West China as well as corresponding physical mechanisms. Thus, this project is motivated to study the long-term change of autumn rain in West China following the idea of observed change-process understanding-future projection. That is, using the observation data and the model simulation data, this study will identify the observed secular changes of autumn rain in West China under the background of global warming, and further explore the roles of polar climate system (including Antarctic Oscillation, Arctic Oscillation, Antarctic sea ice and Arctic sea ice) played in the interdecadal change of autumn rain in West China and the corresponding physical mechanisms. Combing global model simulations with downscaling simulations of the regional model, this study will also project future change of autumn rain in West China. Through this study, it is expected to provide key new knowledge for the understanding of the secular change of autumn rain in West China and the related physical mechanism, and provide scientific support for climate change adaptation as well as disaster prevention and mitigation.