一次冰雹天气的WSR-88D双偏振雷达特征分析  

Analysis of the WSR-88D Dual-polarization Radar Characteristics in a Hail Case

作　　者：刘红亚[1] 杨引明 张晶[1] 赵畅 Liu Hongya;Yang Yinming;Zhang Jing;Zhao Chang(Shanghai Central Meteorological Observatory,Shanghai 200030,China;Tianjin Meteorological Bureau,Tianjin 300074,China)

机构地区：[1]上海中心气象台,上海200030 [2]天津市气象局,天津300074

出　　处：《气象与环境科学》2020年第2期1-10,共10页Meteorological and Environmental Sciences

基　　金：上海市科委项目(18dz1200400);国家自然科学基金项目(41975069)。

摘　　要：受高空冷空气和低空切变线共同影响,2015年4月28日,一次长生命史冰雹强风暴袭击了上海西南部地区,位于南汇的WSR-88D双偏振雷达在可视范围内进行了全程监测。利用天气图资料和双偏振雷达资料,分析了这次风暴形态的时间演变和双偏振特征。分析结果表明,强风暴中心水平反射率因子普遍超过60 dBZ,发展高度超过了15 km,中下层出现了有界弱回波区和钩状回波,径向速度图上还出现了中气旋;风暴发展旺盛时段出现了明显的“非均匀波束充塞”现象,风暴中心附近中底层出现了低差分反射率的冰雹信号(差分反射率洞)、高差分反射率弧(超过4.0 dB)、高比差分相位脚(超过4°·km^-1)和低相关系数区(低至0.8),强烈的上升气流区将低层液态水和各种降水粒子带到高层,导致高层出现了差分反射率柱和比差分相位柱,高度伸展到了-20℃层以上,并与较低的相关系数(0.9左右)相对应,以上各种特征证明了冰雹的存在。最后,在强风暴传统概念模型的基础上,根据双偏振特征,归纳出了这次风暴的概念模型,给出了各种典型特征的水平和垂直位置关系,并根据传统的动力模型,分析了其形成的物理基础。与他人研究结果有所不同的是,本个例的低层高差分反射率弧的范围从风暴中心的前部扩展到相邻的弱回波区。Under the joint influence of upper-level cold air and lower-level shear line,a long-track severe storm passed over southwestern part of Shanghai on 28 April 2015,producing hailstones and gale along portions of its path.The dual-polarization WSR-88D terminal Doppler weather radar located at Nanhui provided close-range in situ operational observations of the storm.In this paper,the temporal evolution and dual-polarization features are analyzed with regard to the storm morphology.The analysis results show that this severe storm had a horizontal reflectivity factor generally larger than 60 dBZ at the center and developed to a maximum height of over 15 km.Bounded weak echo zone and hook echo appeared in the middle and lower levels,and mesocyclone was also found on the radial vertical velocity diagram.Based on comprehensive analyses of dual-polarization radar observations,there was a clear NBF(Non-uniform Beam Filling)phenomenon during the highly developing stages of the storm.Hail signal with low differential reflectivity(ZDR hole),high differential reflectivity arc(ZDR arc,ZDR>4.0 dB),high specific differential phase foot(KDP foot,KDP>4°·km^-1),and low correlation coefficient(ρHV<0.8)were also observed in the mid-low levels near the storm center.Strong updrafts brought the low-level liquid water and various precipitation particles to upper levels,leading to the formation of ZDR column and KDP column extending to over the-20℃layer.Together with a relatively lowρHV below 0.9,these characteristics illustrate the existence of hail.Finally,on the basis of the traditional conceptual model of severe storm,the conceptual model of this storm is summarized according to the dual-polarization characteristics.In addition,horizontal and vertical positional relationships of these features are presented,and preliminary analysis of the possible physical basis for the storm formation is carried out based on the traditional dynamic model of severe storm.What is highlighted for this hail event is that the low-level ZDR arc extende

关 键 词：双偏振 强风暴 冰雹 中气旋 

分 类 号：P458.2[天文地球—大气科学及气象学] P412.25