中文摘要：

利用台站观测降水资料，分析四川盆地及周边地区降水分布和日变化特征，得到以下结论：四川地区降水存在2个高值中心，均位于盆地周围的山地；盆地降水“夜雨”特征明显；川西高原降水峰值以午夜前降水量的贡献为主；盆中与盆地西南边缘山地的降水峰值由夜间降水量与降水频率共同作用；盆地东北边缘的山地是午前降水频率与后半夜的降水量均有贡献。其次，结合WRF模式的数值试验，对2008年9月23～24日发生在盆地的夜间暴雨过程进行模拟研究和综合分析。结果表明WRF模式较好地模拟了此次天气过程降水的空间分布和日变化规律，通过分析模拟的环流场与温湿场发现，夜雨的形成与大尺度环流场的影响和地形强迫关系密切。

英文摘要：

6-hourly precipitation data from station rain gauge records are employed to study the distribution and diurnal cycle of rainfall in the Sichuan Basin and its neighboring region of it. The results show that： There are two high rainfall centers over the peripheral mountain land of the Sichuan Basin; Nocturnal rainfall dominates this region; The peak value of daily rainfall amount in the West Sichuan Plateau mainly comes from early-midnight 6 h precipitation amount; It comes from night 6 h precipitation amount and frequency over the centre region of the Sichuan Basin and the western periphery of basin while the forenoon frequency and late-midnight 6 h amount dominate the northeastern periphery of the basin. And then, mid-night heavy rainfall event during September 23 - 24 2008 over the basin was simulated by using the Weather Research and Forecasting Model （WRF）. The mechanisms responsible for the diurnal variation of the rainfall are addressed by analyzing the model outputs. The results show that the WRF model can simulate well the spatial distribution and diurnal variation of averaged precipitation in the Sichuan Basin, the topography forcing and large-scale circulation are related to the formation of mid-night maximum rainfall.