一次副热带高压控制下的龙卷雷达回波特征分析  

Echo Characteristics of Tornado Radar under the Control of a Subtropical High

作　　者：刘懿枢 马中元[1] 魏鸣[3] 余剑浩 陈鲍发 李密 彭莎 LIU Yishu;MA Zhongyuan;WEI Ming;YU Jianhao;CHEN Baofa;LI Mi;PENG Sha(Jiangxi Institute of Meteorological Sciences,Nanchang 330046,China;Yingtan Meteorological Bureau,Yingtan 335001,China;Nanjing University of Information Engineering,Nanjing 210044,China;Jingdezhen Meteorological Bureau,Jingdezhen 333000,China)

机构地区：[1]江西省气象科学研究所,江西南昌330046 [2]鹰潭市气象局,江西鹰潭335001 [3]南京信息工程大学,江苏南京210044 [4]景德镇市气象局,江西景德镇333000

出　　处：《沙漠与绿洲气象》2023年第3期35-43,共9页Desert and Oasis Meteorology

基　　金：国家自然科学基金项目(41675029);中国气象局气象关键技术集成与应用项目(CMAGJ2013M74);中国气象科学研究院开放课题(2012LASWB01);南京雷达气象与强天气开放基金(BJG201205)。

摘　　要：利用江西WebGIS雷达拼图、单部雷达产品、常规天气、自动站和探空等资料,采用雷达气象学、天气学和中尺度分析等方法,对2020年8月21日江西省九江市都昌县出现的一次龙卷过程进行分析,结果表明:(1)龙卷发生在江西副热带高压(简称“副高”)控制下,地面温度锋区和湿度锋区为对流发生提供动力、热力和湿度梯度条件。(1)龙卷发生前,回波合并排列成短带;龙卷发生时,短带回波南端转为向南延伸发展,强回波边缘陡直,呈狭窄短带形态;60 dBZ强回波中心位于狭窄短带回波后部,都昌县龙卷产生在强回波之中。(3)龙卷回波速度场正负速度对明显,辐合较强,正负速度差值可达20 m·s^(-1);低仰角正速度区面积较大,高仰角正速度面积减小。(4)反射率因子垂直剖面RCS(Reflectivity Cross Section)图上,强回波顶高在7 km以下;径向速度垂直剖面VCS(Velocity Cross Section)图上,具有速度辐合结构,达到弱切变标准。A tornado process in Duchang county,Jiujiang city,Jiangxi province,on August 21,2020,was analyzed by using the data of Jiangxi WebGIS radar mosaic,single radar products,conventional weather,observation of automatic station,and radio-sounding,and using the methods of radar meteorology,meteorology,and mesoscale analysis.The results show that:(1)Tornadoes occurred under the control of Jiangxi subtropical high.The surface temperature and humidity front provide dynamic,thermal,and humidity gradient conditions for convection.(2)Before the tornado,the echoes were combined and arranged into short bands;When the tornado occurs,the southern end of the short band echo turns to extend southward,and the edge of the strong echo is steep and narrow;The 60 dBZ intense echo center was located behind the little short band echo,and the Duchang tornado was generated in the strong echo.(3)The positive and negative velocity pairs of the tornado echo velocity field were evident,the convergence was strong,and the difference of positive and negative velocity reached 20 m·s^(-1);The area of positive velocity at low elevation was more significant,and the area of positive velocity at high elevation was smaller.(4)On the RCS(reflectivity cross-section)of the reflectivity factor vertical section,the top height of the strong echo was less than 7 km;The radial velocity vertical section VCS(velocity cross-section)had a velocity convergence structure,reaching the weak shear standard.

关 键 词：江西 都昌龙卷 雷达回波 

分 类 号：P445.1[天文地球—大气科学及气象学]