两次冷涡天气的多普勒雷达资料对比分析

Comparative Analysis of Doppler Weather Radar Data from Two Cold Vortex Weather Events

运用常规天气资料和新一代天气雷达资料对2008年6月承德市两次冷涡天气过程进行对比分析发现:高空冷涡和低层中尺度切变线,是两次过程共同的影响系统,东蒙冷涡造成的强对流天气和冷涡的移动路径有关;高低空风场的配置和通气管指数可判断垂直风切变的大小;多普勒雷达基本反射率因子的形态、强度、移速、垂直结构等特征及平均径向速度场中尺度辐合线、逆风区、垂直切变和零速度线走向等对强天气的预警有较强的指示作用;垂直累积液态水含量(VIL)值的跃增和剧减对强天气预警有明显的指示意义,VIL值在对流发展阶段逐渐增长,随强天气开始对流减弱而减小。

By means of conventional weather data and new generation weather radar data in June 2008 at Chengde,two cold-vortex weather events are compared and analyzed.It is found that an upper-level cold vortex and a lower-level mesoscale shear line are the common influencing systems;severe convective weather caused by the eastern-Mongolia cold vortex is related to the moving track of the cold vortex;the configuration of the wind fields at lower and upper levels and the chimney index are used to determine the size of the vertical wind shear;such factors are highly indicative to severe weather warning as the shape,strength,moving speed,vertical structure characteristics of Doppler radar basic reflectivity,as well as the moving directions of the mesoscale convergence lines,adverse wind areas,vertical shear lines,zero-speed lines on the average radial velocity fields;the jumps and drastic reduction of VIL values have also great significance,VIL increasing gradually with development at the convection stage and decreasing after the beginning of convective weather.