中文摘要：

利用降水实况资料、单站地面资料、FY2E云顶亮温和NCEP、ECMWF格点资料,对2012年7月20日（7·20）、29日（7·29）腾格里沙漠发生的2次暴雨过程进行了诊断分析。结果表明：20∶00局地热力环流在抬升、水汽动量辐合等方面为暴雨提供了有利条件,但它们必须得到天气系统的加强和优化,才能触发中尺度对流天气;沙漠的北边界为持续的水汽输入,南、东边界在暴雨前后由输入转为输出,西边界则由输出转输入,水汽源地在南海、孟加拉湾以及高纬地区;2次暴雨过程都在有利的大尺度环流背景和高低层天气系统相互作用下产生,垂直方向上形成抽吸结构;7·29过程前期为强不稳定层结,引发暴雨的中尺度系统是MCC,而7·20过程层结相对较稳定,观测点降水主要由中β尺度对流系统引起,这是7·29过程降雨大于7·20过程的原因。

英文摘要：

A Diagnostic analysis on the formation causes of two rainstorms in the Tengger Desert on July 20 and July 29,2012 was carried out using the surface precipitation data,meteorological data observed by single station,FY-2E satellite images and gridded data from NCEP and ECMWF FNL. The results showed that despite the local thermodynamic circulation at 20： 00 provided the favorable conditions of occurring rainstorm from the aspects of thermal lifting and convergence of water vapor and momentum,they were too weak to trigger a mesoscale convective weather unless being strengthened and optimized by the force of large scale weather systems. Water vapor was continuously transported to the north boundary of the desert,its input was changed into output over the south and east boundaries around the occurrence of rainstorms,but the situation was opposite over the west boundary. The main sources of water vapor to the study area for forming the 2 rainstorms were the Bengal Bay,South China Sea and high-latitude area. Two rainstorms occurred under the circumstance of favorable large-scale circulation and the interaction between weather systems at different levels,while the vertical configuration of divergence and convergence formed a suction structure to provide the impetus for the intense upward movement. An unstable stratification at the earlier stage of the weather process on July 29 was much stronger than that on July 20,and the heavy rains at the observation site were separately caused by MCC and βMCS,which was the reason that the rain intensity of the former was much higher than that of the latter.