铜仁市一次局地大暴雨天气的雷达回波特征分析

The Analysis of Radar Echo Features of a Local Torrential Rain in Tongren

为了探明局地大暴雨天气的发生原因和发展过程,降低其给农业生产带来的损失,提高大暴雨天气的预报准确率,利用铜仁市气象局新一代多普勒雷达观测资料结合各县(区)气象观测站的常规气象资料及地面雨量观测记录数据对贵州省铜仁市中东部2013年9月10日的局地大暴雨天气雷达回波特征进行综合分析。结果表明:1)在混合降水云系中,分散积层混合型回波在较长时间内聚集稳定、少动,并呈"准静止状态"和"列车效应"的回波现象,是导致局地大暴雨天气发生的主要原因。2)在混合降水回波中存在多个对流回波柱、且强回波核位于云体中下部的回波垂直结构特性是识别、判断局地大暴雨天气的重要特征。3)在暴雨发生前,对流层的辐合强度和厚度增强,并出现高层辐散;在降水减弱阶段,低层辐合减弱并逐渐变为辐散,高层辐散也逐渐减弱最后转为整体下沉的回波径向速度特征反映了局地暴雨天气的演变发展过程。

In order to explore the occurrence reason and development prdess of torrential rain,so as to decrease the loss brought by local torrential rain in agricultural production and increase the forecast accuracy of torrential rain,the authors used a new Doppler weather radar data,and combined with conventional meteorological data and rainfall observation records to analyze a local rainstorm weather process on September 10,2013in the middle part of Tongren,Guizhou.Results：1）The direct reason for the heavy rain weather in some areas of Tongren was low trough,low vortex deepening,low vortex shear line and the West Pacific subtropical high and stable less dynamic barrier eastward and ground cold air intrusion.2）In the mixture of rain clouds,scattered laminated hybrid echo kept stable,less dynamic, gathered a＂quasistationary state＂and strong echo rainband constitute the＂train effects＂in a long time was conducive to the heavy rainstorm weather.3）In the mixed precipitation echoes in the presence of multiple convective echo column,strong echo nucleus located in the lower cloud was important to recognize and judge the feature of rainstorm.In the radial velocity,The change of positive and negative velocity and zero velocity line could reflect the development process of the rainstorm weather.4）Before the occurrence of the rainstorm,the intensity and the thickness of convergence of troposphere was enhanced,and divergence emergenced;in the weakening stage,low level convergence weaken and gradually became divergence, divergence was also gradually weakened,and finally into the sinking in the whole.In the radial velocity figure,the variation of plus or minus speed zone and zero velocity curve reflected the evolution process of torrential rain.