华西秋雨是我国西部地区秋季多雨的一种特殊型的高影响天气气候事件。近年来伴随着全球变暖，华西秋雨在四川盆地东部、三峡库区等地区有显著增多或增强趋势，对我国国民经济持续发展、三峡工程综合效益的发挥以及自然生态等诸多方面有巨大影响。.本项目利用多种长序列气象要素观测资料、NCEP/NCAR 和ECMWF 再分析资料，在分析不同气候区域华西秋雨变化事实的基础上，建立能够客观反映华西秋雨强弱变化的指标序列；揭示华西秋雨年际和年代际变化规律及其变异机理；研究夏秋过渡季节大气环流转换过程中，东亚冬夏季风进退、青藏高原季风和南亚季风变化对华西秋雨形成和变异的影响；研究印度洋海温和南亚高压等强迫系统异常结构配置特征对华西秋雨形成和维持的物理机制。在此基础上，根据揭示的华西秋雨变化规律及其与外强迫因子的物理联系，提出预测华西秋雨的新思路和新方法，为提高华西秋雨预测准确率提供科学基础。

Autumn rain in Western China(ARWC) is one of the distinct high-impact climatological weather events in the fall of Western China.In recent years, the amount of ARWC over the Eastern Sichuan basin, the three Gorges reservoir area and other regions show obvious increasing trend and the strength of that also enhanced under the background of global warming. These kinds of changes highly impact on the national sustainable development, the benefit of the Three Gorges Project, and the natural ecosystems. The data-sets used in this project include a variety of long-recording observational data, NCEP/NCAR reanalysis data and ECMWF reanalysis data. Based on the analysis of the autumn rain variations over different climatic regions of western China, the objects of this project are to establish a time series which can objectively describe the strength of ARWC, and to reveal mechanisms of inter-annual and inter-decadal change of autumn rain. The impacts of the propagation of East Asian summer and winter monsoons, the change of Tibetan Plateau monsoon and South Asian Monsoon on ARWC in the transitional large-scale circulation between summer and autumn will be estimated. The roles of different structure combinations of Indian Ocean sea surface temperature and High pressure in south Asia in forming and maintaining ARWC will also be detected. On the basis of revealing the regularity of the variations of ARWC associated with the physical connections of the forcing factors, a prediction method will be promoted in order to improve the forecasting skill of ARWC.