苏州一次EF3级龙卷的双偏振雷达特征分析

Analysis of Bipolarized Radar Characteristics of an EF3 Tornado in Suzhou

利用再分析资料、探空资料和双偏振雷达资料分析了2021年5月14日发生在江苏苏州的EF3级龙卷。研究发现,龙卷发生在江淮准静止锋南侧的暖区内,龙卷发生前苏州地区有较强的大气不稳定、较低的抬升凝结高度和较强的垂直风切变。龙卷风暴经过2次风暴合并进入成熟期,成熟的龙卷风暴具有典型超级单体的钩状回波和强中气旋特征,并伴有龙卷涡旋特征(TVS)。风暴合并产生的强垂直风切变导致风暴内降水分布存在明显的分界线,差分反射率(ZDR)和差分传播相位常数(KDP)大值中心发生分离。KDP中心位于前侧下沉区(FFD),以数浓度较高的小雨滴降水为主;ZDR中心位于前侧阵风锋(FFGF)附近,以大雨滴降水为主,大雨滴形成的弱冷池有利于龙卷的产生。

This paper analyzes the EF3 tornado in Suzhou,Jiangsu Province on May 14,2021,using reanalysis data,radiosonde data and bipolar radar data.The study found that the tornado occurred in the warm zone on the south side of the Jianghuai quasistatic front.Before the tornado,there were strong atmospheric instability,low uplift condensation height and strong vertical wind shear in Suzhou.After two storms merging,the tornado enters the mature period.The mature tornado has the characteristics of hook echo of typical supercell,strong mesocyclone,and tornado vortex(TVS).The strong vertical wind shear caused by storm merging leads to the clear boundary of precipitation distribution in the storm,and the centers of large values of differential reflectivity(ZDR)and differential propagation phase constant(KDP)were separated.The KDP center was located in the front subsiding zone(FFD),and mainly consists of small raindrops with high concentration;The ZDR center was located near the front gust front(FFGF),which was dominated by heavy raindrops.The weak cold pool formed by heavy raindrops was conducive to the generation of tornadoes.