江西一次副高边缘雷暴大风回波特征分析

Analysis on the Characteristics of Thunderstorm Gale Echo at the Edge of Jiangxi Subtropical High on July 11th

为研究江西副热带高压边缘雷暴大风天气的演变和雷达拼图回波特征,使用天气形势、卫星云图、江西WebGIS雷达拼图等资料,对2020年7月11日江西副热带高压边缘雷暴大风天气过程,采用统计分析、天气分析和回波图像分析等方法进行分析,结果表明:本次过程共造成江西国家站9站雷暴大风、1站西南大风,区域站63站雷暴大风。天气影响系统表现为高层反气旋环流、中层处副高边缘、低层西南急流、低涡、切变线及地面辐合线。卫星云图上中尺度对流云团MCS的移动与合并、加强,云顶亮温达-60~-80℃。雷达拼图回波上表现为副高边缘局地热雷雨发展、合并成为回波短带、“弓”状回波带,雷暴大风就发生在回波短带凸出部位前沿;回波短带组合反射率CR达55~60 dBz,垂直液态水含量VIL达25~30 kg/m^(2),回波顶高ET达14~15 km;风暴跟踪信息STI有助于预报员识别和判断回波系统的移动,从而发布更为精准的预报预警信息。这些为副热带高压边缘雷暴大风的有效预警提供了参考依据。

In order to study the evolution of thunderstorm gale at the edge of Jiangxi subtropical high and the echo characteristics of radar jigsaw puzzle,the thunderstorm gale process at the edge of Jiangxi subtropical high on July 11,2020 was analyzed by statistical analysis,weather analysis and echo image analysis.The results show that this process caused thunderstorm gale at 9 stations in Jiangxi National Station,southwest gale at 1 station and thunderstorm gale at 63 stations in regional stations.The weather influence system is characterized by anticyclonic circulation in the upper layer,subtropical high edge in the middle layer,southwest jet stream in the lower layer,vortex,shear line and surface convergence line.The MCS of mesoscale convective cloud cluster moves,merges and strengthens on satellite cloud picture,and the bright temperature of cloud top reaches-60~-80℃.The radar mosaic echo shows that the geothermal thunderstorm develops at the edge of the subtropical high and merges into an echo short band and a bow-shaped echo band,and the thunderstorm gale occurs at the front of the protruding part of the echo short band.The combined reflectivity CR of echo short band is 55~60 dBz,the vertical liquid water content VIL is 25~30 kg/m^(2),and the echo top height ET is 14~15 km.Storm tracking information STI is helpful for forecasters to identify and judge the movement of echo system,so as to release more accurate forecast and warning information.These provide a reference for the effective warning of thunderstorm gale at the edge of subtropical high.