飑线优化识别及雷暴大风分析

Optimal Identification Method of Squall Line and Thunderstorm Winds Analysis

飑线是产生灾害大风的重要系统,强度和影响范围大。本文在线状中尺度对流系统自动识别基础上,提出了飑线优化识别方法,识别主要参数选取反射率因子、长轴长度、系统面积和线性程度,按照反射率因子5 d BZ递增原则,选取四组识别参数对雷达回波多次识别,择优选取线性程度高且包含较强回波的飑线作为当前体扫的飑线最优识别结果。通过对140个体扫126个飑线识别效果检验和对应大风分析,结果表明:优化识别方法能够同时识别强、弱飑线,真实反应飑线发展的不同阶段,比单一参数识别效果明显改善,优化识别命中率分别比四组参数识别提高了26.3%、10%、40%和89%;在有利的环境条件下,雷暴大风出现在飑线的强回波带、弓形回波前沿和线风暴之间断裂带上,飑线识别区域与灾害大风吻合,可作为大风预警区域;飑线大风的风向基本沿风暴移动方向吹。

Squall line is an important system to produce thunderstorm wind,which has great strength and wide influence. Based on automatic identification of linear mesoscale convective system,optimal identification method of squall line is put forward. The main parameters are reflectivity factor,long axis length,area and linear degree.The radar echo is identified by using four groups single parameters,reflectivity factor is increased by 5 dBZ. It is the best result of optimal identification which has high linear degree and strongest echo. The performance of the method is evaluated and the corresponding wind is analyzed based on 140 body scan and 126 squall lines,the results show： The optimal identification method can identify strong and weak squall line at the same time,really response squall line at different stages of development,and the effect is improved more obviously than single parameter method. The hit rate of optimal identification method is improved 26. 3%,10%,40% and 89% than the method of four groups single parameters identification. Strong thunderstorm winds occur in strong echo band of squall line,bow echo edge and the gap between different storms,the area of squall line recognition and disaster winds is quite similar,and it can be used as a gale warning area. The wind direction of squall line is mostly along the moving direction of the storm.