利用高空、 地面定时观测资料、 区域站降水资料、 FY-2E红外云图和NCEP 1°×1°再分析资料， 对2011年6月15-16日甘肃敦煌、 阿克塞和肃北的一次历史罕见暴雨天气过程的影响系统、 水汽条件、 广义湿位涡及其倾向变化进行了分析。结果表明, 这次暴雨是中高纬天气系统与低纬天气系统相互作用的结果。暴雨水汽来源于700 hPa新疆东部偏西气流输送和600 hPa附近河西走廊西部偏东气流输送。广义湿位涡正异常主要集中在850~750 hPa广义位温线密集区， 这与实际大气水汽主要集中在低层是一致的， 在一定程度上反映出暴雨期的水汽分布和水汽集中特征。800 hPa上广义湿位涡的正异常区基本与暴雨区一致， 与湿位涡相比， 广义湿位涡能更好地诊断出这次暴雨落区。广义湿位涡正异常大值区出现在绝对涡度异常大值区与大的相对湿度梯度相重叠的区域。单点广义湿位涡倾向异常值的负正、 正负转换及峰值变化与降水开始、 结束和雨强变化相一致。广义湿位涡除了可作为一个分析暴雨系统发生、 发展的动力变量外, 还可体现出暴雨时期高水汽集中的特点， 在暴雨分析中有一定的优势。
Using the sounding and surface data, the satellite cloud images and the NCEP reanalysis data with 1°×1°, the synoptic situation, water vapor condition and generalized moist potential vorticity (GMPV) of the torrential rainstorm occurred in Dunhuang from 15 to 16 June 2011 are analyzed. The results show that this torrential rainstorm is caused by the interaction of the middle-high latitude weather system and the low latitude weather system. The water vapor transport is originated from the westerly air current on 700 hPa in the eastern Xinjiang and the easterly air current near 600 hPa in the western Hexi Corridor. The positive anomaly of GMPV mainly occurs in the dense region of generalized potential temperature isoline between 850~750 hPa, which reflects the water vapor distribution during torrential rainstorm. The GMPV positive anomaly area on 800 hPa is basically consistent with the torrential rainstorm area. Comparing with the MPV, the GMPV can diagnose location of this torrential rainstorm well. The GMPV positive anomaly is occurring the region of overlap between the absolute vorticity great anomaly value and the great relative humidity gradient. The transformation from negative to positive, the transformation from positive to negative and the peak value change of the GMPV tendency of single point are consistent with the precipitation beginning, ending and the rainstorm intensity change, respectively. The GMPV and its tendency not only can be taken as dynamical variables to analyze the location and intensity tendency of torrential rainstorm, but also can reflect the distribution and concentration of water vapor, which are useful for the analysis of torrential rainstorm cases.
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