苏北2020年6月12日高邮龙卷的形成机理和回波演变分析  

ANALYSIS OF FORMATION MECHANISM AND ECHO EVOLUTION OF GAOYOU TORNADO ON JUNE 12,2020 IN NORTHERN JIANGSU

作　　者：王琛 魏鸣[1] WANG Chen;WEI Ming(Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters,Nanjing University of Information Science&Technology,Nanjing 210044,China)

机构地区：[1]南京信息工程大学/气象灾害预报预警与评估协同创新中心,江苏南京210044

出　　处：《热带气象学报》2021年第5期812-823,共12页Journal of Tropical Meteorology

基　　金：国家自然科学基金项目(41675029);山东省自然科学基金面上项目(ZR2020MD052、ZR2020MD053)共同资助。

摘　　要：苏北平原易发龙卷,为深入认识其形成机理和回波演变特征,针对2020年6月12日江苏高邮的一次EF2级的龙卷,利用NCEP/NCEP再分析资料、探空资料、V-3θ资料、葵花8号静止卫星资料和双偏振雷达资料对本次龙卷天气过程进行详细分析。(1)苏北的天气形势处于强的热力不稳定状态,尤其是925~850hPa呈现罕见的变干变冷结构,有利于龙卷的爆发。(2)龙卷形成前经历了两个阶段的风暴单体合并,回波合并加强了不稳定能量。(3)中气旋和TVS对龙卷有预警作用,龙卷发生前的23min和17min,雷达分别探测到了中气旋和TVS;龙卷及地时,雷达同时探测到了气旋性TVS和反气旋TVS,据此提出了一种龙卷涡管的三维结构模型。(4)速度谱宽大值区的出现是预警龙卷的有效信息。(5)龙卷发生时,出现了龙卷碎屑特征、Z_(DR)柱和K_(DP)柱等显著特征。研究结果为深入认识苏北平原龙卷的演变特征并改进预警提供了参考依据。Tornadoes attack the northern Jiangsu plain frequently.To understand the formation mechanism and echo evolution characteristics of a tornado that hit Gaoyou,Jiangsu on June 12,2020,the present study uses NCEP/NCEP reanalysis data,sounding data,V-3θ data,Himawari-8 data,and dual polarization radar data for analysis.The results show that:(1)The weather at that time in northern Jiangsu was in a state of strong thermal instability.The air from level 925 hPa to level 850 hPa was drier and cooler than usual,which was rarely seen.This was conducive to the outbreak of tornado.(2)Before the formation of the tornado,there were two stages of merging of cells,and merging of echo showed the instability energy was enhanced.(3)Middle cyclone and tornadic vortex signature(TVS)are good indicators of tornado occurrence.23 minutes and 17 minutes before the tornado,radar detected a middle cyclone and TVS.When the tornado reached the ground,radar detected both cyclonic TVS and anticyclonic TVS.Given the above results,the present study has proposed a three-dimensional structure model of tornado vortex tube.(4)The large velocity spectrum width area is also a good indicator of tornado occurrence.(5)When the tornado reached the ground,the tornado debris signature,Z_(DR) column,and K_(DP) column appeared.The results provide a reference for further research of the evolution characteristics of tornado in the northern Jiangsu plain and may help improve early warning.

关 键 词：龙卷 双偏振雷达 形成机理 回波演变 预警 

分 类 号：P445.1[天文地球—大气科学及气象学]