中文摘要：

利用常规地面和探空气象观测资料、自动气象站资料、卫星和雷达拼图资料以及NCEP FNL分析资料对2013年7月3-5日四川盆地强降水过程的中尺度对流系统及其环境场特征进行了分析。结果表明：此次降水过程分为三个阶段,分别对应三次中尺度对流系统的发生、发展;700 h Pa切变线和850h Pa低涡为中尺度对流系统的产生提供了有利的动力条件,中尺度对流系统沿700 h Pa切变线以及850h Pa低涡中心附近发生、发展,三个阶段的中尺度对流活动均与低层切变系统的发展、演变相吻合。冷空气对中尺度对流系统的发生发展具有重要影响,强降水的产生时间和空间分布均与冷空气入侵密切相关。四川盆地地形对强降水的产生有两方面的作用,一是使气流在山前辐合抬升,二是使冷空气堆积造成强的冷暖空气对峙,导致锋生作用加强。

英文摘要：

To study the mesoscale convective systems（ MCSs） and the characteristics of environment field of a heavy rainfall process occurred in Sichuan Basin on early July 2013,data of conventional surface and sounding observation stations,meteorological automatic stations as well as the associated NCEP FNL（ 1° ×1°） final analysis data are employed in this paper for synoptic meteorological analysis. It is shown that the rainfall process contains three stages corresponding to the generation and evolution of three different MCSs. The 700 h Pa shear line and 850 h Pa lowvortex provide favorable dynamical conditions for the generation of MCSs. MCSs in the three stages all locate along the 700 h Pa shear line or near 850 h Pa lowvortex center and all coincide with the evolution of low-level systems very well. Cold Air intrusion is very important to the evolution of MCSs in the Sichuan Basin’s heavy rainfall event. Both the initiation time and spatial distribution of heavy rainfall are closely related to the intrusion of cold air. The results also showthat topography of Sichuan Basin has two aspects of effects on the generation of MCSs. On one side,topography could result in strong ascending motions at mountain front areas,while on the other side it may induce strong thermal contrast between cold and warm air by accumulating cold air which could enhance the frontogenesis.