苏南一次梅雨锋大暴雨的环境条件及对流系统演变特征  

Analysis of environmental conditions and characteristics of convective system evolution of a Mei-Yu Front heavy rainstorm in southern Jiangsu

作　　者：曹舒娅 邹兰军[2] 王易 慕瑞琪 周正明 CAO Shuya;ZOU Lanjun;WANG Yi;MU Ruiqi;ZHOU Zhengming(Suzhou Meteorological Bureau of Jiangsu Province,Suzhou 215131;Shanghai Central Meteorological Observatory,Shanghai 200030;Jiangsu Meteorological Observatory,Nanjing 210019)

机构地区：[1]江苏省苏州市气象局,苏州215131 [2]上海中心气象台,上海200030 [3]江苏省气象台,南京210000

出　　处：《暴雨灾害》2023年第5期532-540,共9页Torrential Rain and Disasters

基　　金：江苏省气象局重点科研项目(KZ202108);上海市长三角科技创新共同体领域项目(21002410200)。

摘　　要：受梅雨锋及梅雨锋上中尺度低涡影响,2020年7月6日江苏省苏州市出现大暴雨,造成城市内涝等灾害。利用欧洲中期天气预报中心ERA5再分析资料及自动气象站、多普勒天气雷达、风廓线雷达等多种观测资料,分析了此次大暴雨过程的天气背景、环境条件、对流系统演变等特征。结果表明:(1)高空西风槽东移,中低层冷式切变线南压,冷暖空气在苏南上空汇合使低层辐合增强,中低层西南急流加强以及地面梅雨锋维持为此次大暴雨过程提供了有利的天气背景条件。(2)最强降雨时段回波中心强度超过60 dBz,顶高超过14 km,强反射率因子区对应差分传播相移率达7°·km-1高值区,强回波垂直伸展高度平均在6 km以下,为典型的低质心暖区降雨。(3)苏州上空抬升凝结高度低、中等强度的对流有效位能、中低层强垂直风切变和对流不稳定层结,为大暴雨的产生提供了有利的环境条件。不断增强的低空急流向下传播形成超低空急流,急流出口区强烈的辐合抬升和切变线上空次级环流的上升支叠加,为强降水的产生提供了动力抬升和触发条件。水平方向和垂直方向强烈的梅雨锋锋生,使强降水得以维持。Affected by the Mei-Yu Front and the mesoscale vortex on the Mei-Yu Front,a heavy rain event occurred in Suzhou on 6 July,2020,and caused disasters such as urban waterlogging.In this paper,by using ERA5 reanalysis data from the European Center for Medi⁃um-Range Weather Forecasts,as well as various observational data from ground meteorological stations,Doppler weather radar,and wind profile radar,we analyze the weather background,environmental characteristics,convective system evolution,and maintenance mechanism of this heavy rain process.The results show that:(1)The upper westerly trough moved eastward,the cold shear line at the middle and lower lev⁃els pressed southward,the convergence of cold and warm air over southern Jiangsu enhanced the convergence at the lower level,the strength⁃ening of the southwest jet at the middle and lower levels and the maintenance of the ground quasi stationary front provided favorable weather background conditions for the heavy rainstorm process.(2)During the strongest rainfall period,the intensity of the radar echo center is 60 dBz and the top height exceeds 14 km.The strong reflectivity factor area corresponds to a differential propagation phase shift of 7°·km-1.The aver⁃age vertical extension height of the strong echo is below 6 km,making it a typical low center of mass warm area rainfall.(3)The moderate lev⁃els of convective availble potential energy,strong vertical wind shear in the middle and lower levels,and convective instability stratification,and the low lifting condensation level over Suzhou provide favorable environmental conditions for the generation of heavy rainstorm.The con⁃tinuously increasing low-level jet propagates downwards,to forming an superultra low-level jet.The strong convergence and uplift in the jet exitoutflow area,combined with the rising branches of the secondary circulation above the shear line,provide dynamic uplift and triggering conditions for the generation of heavy precipitation.The strong frontogenesis of the Mei-Yu Front in both

关 键 词：梅雨锋 列车效应 低空急流 锋生函数 

分 类 号：P458.3[天文地球—大气科学及气象学]