一次下击暴流天气的多普勒雷达资料分析  

Analysis of a downburst using Doppler radar data

作　　者：王楠[1] 刘黎平[2] 仲凌志[2] 

机构地区：[1]陕西省气象台,西安710016 [2]中国气象科学研究院,北京100081

出　　处：《南京信息工程大学学报（自然科学版）》2009年第3期273-278,共6页Journal of Nanjing University of Information Science & Technology（Natural Science Edition）

基　　金：2009年中国气象局"新一代天气雷达信息共享平台建设"项目

摘　　要：利用多普勒雷达基本反射率、径向速度资料以及径向速度计算的风切变结果,对一次典型的下击暴流天气过程进行了分析.结果发现:强对流单体合并加强形成弓状回波,在弓状回波前沿反射率因子梯度大值区产生下击暴流,造成地面强风灾害;下击暴流过程中,中层以上一直存在强度不断增大的径向风辐合,为系统发展提供动力支持;下击暴流发生时,底层会出现相应的径向风辐散,是地面大风的直接反应;高低层垂直切变反映了强对流单体内部风场配置结构为底层有较强的暖湿入流、高层有明显的上层出流、中层以上升气流为主,这样的流场配置正是一般强对流单体中的常见特征.The Doppler radar data of basic reflectivity and radial velocity, and the wind shear calculated from radial velocity are utilized to analyze a typical weather course of downburst. The results show that two strong convection cells are merged and hence strengthened to form a bow echo, and the downburst breaks out at the fore part of the bow echo where reflectivity grade is high, resulting in strong wind disaster on the ground. In the course of a down- burst,there always exists in mesosphere or higher altitudes the convergence of radial velocity with a growing strength, supplying and congregating abundant energy for the downburst. The corresponding divergence of radial velocity near the ground appears when a downburst breaks out, which directly results from a gust front. The configuration structure of the wind field inside strong convection cells reflected by the high-and low-level vertical wind shear is as follows ：there are warm and humid in-currents near the ground, obvious upper-level out-currents in high altitudes and mainly up-currents in mesosphere, which are the common characteristics of the usual strong convection cells.

关 键 词：下击暴流 风切变 多普勒径向速度 

分 类 号：P458.121[天文地球—大气科学及气象学]