2020年夏季鄂西南一次极端暴雨过程成因分析  

Causes of an Extreme Rainstorm in Southwestern Hubeiin the Summer of 2020

作　　者：罗菊英 张家国[2] 许冠宇[2] 黄小彦[2] 章翠红 LUO Juying;ZHANG Jiaguo;XU Guanyu;HUANG Xiaoyan;ZHANG Cuihong(Enshi Region Meteorological Bureau,Enshi 445000,China;Wuhan Central Meteorological Observatory,Wuhan 430074,China)

机构地区：[1]恩施自治州气象局,湖北恩施445000 [2]武汉中心气象台,湖北武汉430074

出　　处：《沙漠与绿洲气象》2023年第2期26-35,共10页Desert and Oasis Meteorology

基　　金：中国气象局预报员专项(CMAYBY2020-083);湖北省气象局重点项目(2021Z01)。

摘　　要：2020年7月26日鄂西南出现了一次极端暴雨过程,建始县城区及附近乡镇在10 h内雨量超过250 mm,导致罕见山洪灾害。利用常规资料,结合地面加密自动站、多普勒天气雷达以及高分辨率EC再分析资料,分析该过程天气形势背景、中尺度环境,以及暴雨中尺度对流系统发生发展过程及其机理,揭示极端暴雨成因。结果表明:(1)中高纬度维持两槽一脊,低纬度副热带高压稳定且位置适中,是鄂西南强降水较长时间维持的有利条件;(2)冷空气侵入四川盆地导致西南涡发展,涡前西南暖湿气流加强,加上鄂西南地形辐合抬升作用,形成深厚正涡度柱和强烈垂直上升运动,是导致极端暴雨产生的重要原因;(3)建始县附近先后经历了后向传播型(BB-QS)及涡旋型(VS)两个中尺度对流系统的影响,而“倒喇叭口”地形导致雷暴冷池逆流并与环境风形成稳定的中尺度辐合上升运动,是极端暴雨中尺度对流系统形成的关键因素。There was an extreme rainstorm in southwestern Hubei on July 26,2020,and the rainfall in Jianshi county and its nearby towns exceeded 250 mm within 10 hours,resulting in rare flash floods.Based on the conventional data,combined with the ground encryption automatic station,Doppler weather radar and high-resolution EC reanalysis data,this paper analyzes the weather background,mesoscale environment,the occurrence and development process of the mesoscale convective system and its mechanism,and reveals the causes of extreme rainstorm.The results show that:(1)Two troughs and one ridge are maintained at medium and high latitudes,and the low-latitude subtropical high is stable and moderate,which are favorable conditions for the long-term maintenance of heavy precipitation in western and southern Hubei;(2)Cold air invading into the Sichuan basin leads to the development of the southwest vortex,the warm and humid air flowing is strengthened in the southwest in front of the vortex,combing with the uplift of irradiation in southern Hubei,forminga deep positive vorticity column anda strong vertical upward motion,which is an important cause of extremely heavy rain;(3)The influence of backward medium-scale convection system(BB-QS)and vortex type(VS)experienced successively.The“inverted horn mouth”terrain leads to a reverse thunderstorm cold pool anda stable mid-scale convergence upward motion with the ambient wind,which is a key factor for the formation of extreme rainstorm meso-scale convective system.

关 键 词：极端暴雨 中尺度系统 地形 

分 类 号：P458.121.1[天文地球—大气科学及气象学]