南疆西部一次突发极端暴雨成因分析

Cause Analaysis on a Sudden Extreme Rainstorm in the West of Southern Xinjiang

利用常规观测、NECP1°×1°再分析、FY2D卫星高分辨率云图及多普勒雷达产品等资料,对2015年8月31日南疆西部突发极端暴雨进行天气诊断及中尺度分析。结果表明:突发暴雨发生在蒙古至贝加尔湖的高压脊经向发展,西西伯利亚低压底部分裂短波槽影响南疆西部的环流背景下,500 h Pa以低槽后干冷的西北气流为主,翻山冷空气和低层高温高湿的环境条件有利于强对流天气的发生发展。突发暴雨与持续性暴雨的水汽输送、水汽辐合及路径均有差异,突发暴雨水汽主要来自南疆盆地前期高能高湿的环境。中低层中尺度切变及辐合是导致暴雨落区及强度不同的原因之一。"人字形"切变,θse能量锋区,中尺度气旋与暴雨中心有很好的对应关系,雷达出现的"逆风区"、VIL大值区和云图出现的干舌在短临预报预警中有一定的指示意义。

Based on conventional observation data, NCEP/NCAR reanalysis data with1°×1°spatialresolution, FY2D high -resolution satellite and Doppler radar products, mesoscale analysis andweather diagnosis are conducted for extreme rainstorm occurred in the west of southern Xinjiang inAug 31st, 2015. It is showed that The high-pressure ridge of Mongolia to Baikal Lake, and thelow-pressure subsurface short-wave trough in western Siberia were the atmospheric background ofsudden rainstorm. Over the rainstorm fall area, the dry and cold northwest airflow is the main flowbehind the trough at 500hPa. The cold air climbed over the mountain and the hot -humidenvironmental conditions of lower atmosphere was conducive to the development of severeconvective weather. The water vapor transport, vapor convergence and path of sudden rainstorm aredifferent from continuous heavy rain . The sudden storm water vapor was mainly from the early stageof high energy and humidity environment in sourthern Xinjiang. Mesoscale shear and convergence inthe middle and lower layer was one of the reasons for the different rainfall area and its intensity.“Herringbone”shear, 兹se energy frontal zone, mesoscale cyclones and torrential rain posses a goodcorresponding relationship.“upwind area”in radar, large buckets in VIL and dry tongue in SatelliteImages havea certain indication funcintion in the in-time forecasting and early warning.