双偏振雷达在江苏“7.6”降雹过程中的应用分析  

Study of “7.6” hail event in Jiangsu based on Dual-Polarization weather radar observations

作　　者：曹舒娅 孙伟 韦芬芬[1] 沈沛丰[1] 何琰 CAO Shuya;SUN Wei;WEI Fenfen;SHEN Peifeng;HE Yan(Suzhou Meteorology Bureau,Suzhou 215131,China)

机构地区：[1]苏州市气象局,江苏苏州215131

出　　处：《大气科学学报》2021年第4期549-557,共9页Transactions of Atmospheric Sciences

基　　金：中国气象局预报员专项(CMAYBY2020-049,CMAYBY2019-041);江苏省气象局重点项目(KZ201806);国家重点研发计划专项(2018YFC1507503)。

摘　　要：针对2019年7月6日发生在江苏徐州、宿迁、淮安、南京以及常州一线的一次大范围冰雹天气过程,利用再分析资料分析天气背景、不稳定机制和抬升条件。通过徐州和南京S波段双偏振雷达偏振参量及宿迁和淮安的双多普勒天气雷达风场反演技术对冰雹云的热动力结构和微物理特征开展了详细的分析。结果表明:此次大范围冰雹天气发生在高空冷涡南落、横槽南摆,低层暖湿气流北抬,上下层强烈不稳定的环流背景下,地面低压缓慢东移南压,提供了辐合抬升条件。此次降雹天气过程中,雷达回波图上显示有典型的冰雹云特征——三体散射长钉、回波穹隆结构、强度超过50 dBZ,中层径向辐合,风暴顶辐散等特征。双偏振雷达各偏振参量也表现出冰雹云的特点,出现冰雹的地区展现水平反射率因子Z_(H)大、差分反射率因子Z_(DR)小、相关系数CC小的特征,Z_(DR)值为-1.0~0.5 dB,CC值小于0.85;超级单体在近地层还出现表征入流区的CC谷、Z_(DR)柱、差分相移率K DP柱等特征。Z_(DR)柱、K DP柱和CC谷等双偏振参量特征在强对流短时临近预报和冰雹识别方面具有很强的应用潜力。双雷达风场反演表明此次过程降雹集中时段,冰雹云的穹隆空间结构,降雹时刻存在的明显下沉气流。Based on the S-band dual polarization Doppler weather radar of Xuzhou and Nanjing,the single polarization radar of Suqian and Huaian,and the reanalysis data,the paper analyzes the circulation background,instability mechanismdynamic,uplift conditions,radar echo and the evolution characteristics of dual polarization radar parameters and the wind inversion technology of dual radar of a wide range hailstorm process accompanied by a thunderstorm and short-term excessive rainfall occurred in Jiangsu Xuzhou,Suqian,Huaian,Nanjing and Changzhou on July 6,2019.The results show that a wide range of strong convective weather occurredwhen the cold vortex falling on high level and horizontal trough swing south,the trough line swept across Jiangsu from north to south before midnight on the 6th,the lower layer warm and humid air flow moved northward,under the background of strong unstable circulation on upper and lower layers,and the low pressure slowly moved eastward and the South pressure provided the convergence and uplift conditions.Generally,the intensity of radar echo is over 50 dBZ and the echo top is always above 10 km in this procedure.Additionally,it appears that there are significant Three Body Scattering Spikes,cyclonic convergence and storm top divergence.A hail storm can be identified by its polarization parameters(such as the Z_(DR),CC,K DP).Hail storm usually exist in the area with strong reflectivity、low value of Z_(DR),and CC.The typical value of Z_(DR) is usually between-1.0 and 0.2 and the value of CC is less than 0.85.Additionally,Z_(DR) and K DP columns help identify hail,thunderstorms,and short-term heavy rainfall.The characteristics of the two polarization parameters above can be used for the prediction of strong convection and hail recognition.As a result of study of the hail period using double radar wind inversion technology,a noticeable downdraft is found.In the three-dimensional flow field structure of the hailstorm supercell,the cyclonic air flow forms at the front of the storm,and then gradually

关 键 词：双偏振雷达 冰雹 风场反演 粒子相态 雷达参量 

分 类 号：P412.25[天文地球—大气科学及气象学]