南疆西部两次极端暴雨中尺度特征对比分析

利用常规气象观测、地面区域气象站逐小时观测数据、FY-2G云顶亮温、喀什CR/CC雷达产品及NCEP再分析等资料，对比分析南疆西部2020年4月17—24日和2021年6月15—17日(分别简称“过程1”、“过程2”)两次极端暴雨过程环流背景和短时强降水环境条件、中尺度特征。结果表明：两次过程均发生在500 h Pa“东西夹攻”的有利环流背景下，100 hPa南亚高压分别呈东部型和双体型，低空急流、切变线和地面中尺度辐合线是两次暴雨重要的触发系统。两次强降水均发生在对流云团发展最强盛、范围最大时或TBB梯度最大处。但雷达回波特征明显不同，“过程1”影响系统为线性多单体强风暴，最大反射率因子达65 dBZ，具有中小尺度辐合和旋转特性，强降水期间VIL维持40 kg/m²以上并有跃增现象，更有利于产生强对流。“过程2”影响系统为分散性普通单体风暴，径向速度高层辐散不明显，VIL值明显小于“过程1”。

Comparative Analysis on environmental conditions and m esoscale characteristics of Two Extreme Rainfall events in West of Southern Xinjiang

Based on the conventional observation data,hourly surface observation data, NCEP reanalysis data,FY-2G satellite cloud picture and CR/CC radar data from Kashi ,environmental conditions and mesoscale characteristics of two extreme rainfall in west of southern xinjiang are analyzed. The results indicate that, both events happened under 500 hPa favorable synoptic situation.,100 hPa South Asia high presented eastern type and double body type,low-level jet stream,shear line and mesoscale convergence lines at surface were important influencing systems to the two extreme rainfall.Water vapor from 500 hPa vortex(trough) and low-level jet stream of 700~850 hPa provided favorable water vapor conditions for the occuring of the extreme rainfall. Heavy rainfall both occured at the maximum gradient of TBB and maximum range .The two events has significant differences in radar echo characteristics.The influencing systems of event1 was multiple-cell Linear storm, maximum reflectivity factor was 65 dBZ and had an obvious characteristic of meso and small scale convergence.VIL stay above 40 kg/m2 during the heavy rainfall.Event2 was caused by isolated cell,.VIL was significantly less than Event1.