广西一次强冰雹天气诊断和预警特征分析

为了提升冰雹天气的短时临近预报和预警服务水平，本研究利用常规观测资料、NCEP再分析资料以及多普勒雷达资料，对广西2013年一次强冰雹天气过程的环境条件和雷达回波结构特征进行分析。结果表明：500 hPa高原槽和南支槽、低层切变线以及地面冷锋是此次强对流天气的影响系统。高空槽前正涡度平流、0~6 km强垂直风切变、较强的大气层结不稳定度、0℃层和-20℃层高度都有利于大冰雹的产生，强对流风暴发生在水汽强辐合区中。产生大冰雹的对流风暴为典型的超级单体风暴，具有低层钩状回波、有界弱回波区、三体散射(TBSS)及持久深厚的中气旋等特征。显著的三体散射回波、60 dBz回波持续扩展到-20℃层高度以上、风暴顶强辐散这些判据可作为判别强冰雹的雷达特征指标。

A Strong Hail Event in Guangxi in 2013: Diagnostics and Early Warning Characteristics

To improve the accuracy of nowcasting and early warning for hail storm, we studied the environmental conditions and radar echo structure of a severe hail event in Guangxi in 2013 by using conventional observation data and NCEP reanalysis data and Doppler radar data. The results showed that: this severe hail event was caused by the 500 hPa plateau trough, the south trough, the low level shear line and the surface cold front; the strong positive vorticity advection in front of the upper trough, strong vertical wind shear between 0-6 km, strong and unstable atmospheric stratification stability, and the appropriate height of 0℃ and -20℃ layers were all conducive to the occurrence and development of hail storms; the severe hail storms occurred in the water vapor convergence zone; the typical supercell storm which had low level hook echo, bounded weak echo area, three body strong scattering (TBSS) and deep persistent mesoscale cyclone produced large hails. Thus, TBSS, 60 dBz echo extending to -20℃ layer and sustained longer time, the strong divergence at the top of storm can be used as indexes to identify severe hail storms.