“07.7”鄂东南强对流天气的多普勒雷达资料分析  

Analysis of "07.7" Severe Convective Events in Southeastern Hubei Province with China New Generation Weather Radar Data

作　　者：肖艳姣[1] 李中华 张端禹[1] 龙利民[3] 

机构地区：[1]中国气象局武汉暴雨研究所,武汉430074 [2]湖北气象信息与技术保障中心,武汉430074 [3]武汉中心气象台,武汉430074

出　　处：《暴雨灾害》2008年第3期213-218,共6页Torrential Rain and Disasters

基　　金：武汉区域气象中心科技发展基金课题(QY-Z-200706);武汉暴雨研究所基本科研业务费专项(0602)共同资助

摘　　要：利用武汉多普勒天气雷达资料,对2007年7月27日发生在武汉及其周边部分地区的一次强对流天气过程,特别是引起武汉、洪湖的冰雹和地面大风灾害的2个强风暴(A、B)进行了详细分析,得到如下结论:(1)这次强对流天气的主要天气背景是,副热带高压西侧强烈的西南气流诱发了中小尺度扰动,强的低层垂直风切变,大的垂直不稳定,低层较干和中高层更干的水汽条件。(2)产生灾害性天气的对流系统最初是一条近乎南北向的断续型对流带,强风暴A和B在其成熟阶段都有低层弱回波和中高层悬垂回波结构,最大回波强度均大于60 dBz;风暴A在其崩溃阶段,近地面径向速度迅速增大,随其北移,造成武汉市黄陂区大风灾害;风暴B在平均径向速度图上存在明显的中层气流辐合(MARC),是即将出现地面强辐散风的标识。(3)强回波中心高度迅速降低是地面灾害性天气发生的标识,VIL密度比VIL本身更能反映风暴的强度,特别是当因雷达扫描策略的影响导致探测不到风暴顶或风暴底时。(4)在用冰雹探测算法(HDA)探测冰雹时,要注意修改可调参数,特别是0℃和-20℃环境温度的高度,这样才能大大降低冰雹误报率。Based on the Wuhan Doppler weather radar data,the severe convective storms, especially two hailstorms A and B, occurred in southeastern Hubei Province on 27 July 2007 are analyzed in detail.As for the synoptic background, meso-scale disturbance led by the southwest jet located in the western to the west-pacific sub-tropic high pressure and the differential temperature advection between lower- and upper-troposphere are quite important to the formation and development of convective instability, the lower troposphere is a little dry with strong vertical wind shear,while the mid and upper troposphere is drier. The initial convective system is a discontinuous convective belt. In the maturity period of hailstorm A （B）, which causes the Wuhan hail and gale （the Honghu hail and downburst）, there are weak echo regions in low layer and overhang echo structures in mid-upper layer. The maximal reflectivities of hailstorm A and B are more than 60 dBz. When hailstorm A collapses, the radial velocity away from radar increases rapidly and reaches 35-40 m/s, and the hailstorm moves toward the north and leads to Huangpi gale. From 20：14 to 20：26, a significant mid level convergence appears in radial velocity images of hailstorm B. At 20：32, the downburst hits the ground. The continued descending of reflectivity core of severe convective storm indicates that ground disaster will occur on hand. Vertically Integrated Liquid Water Density can describe storm strength more appropriate than Vertically Integrated Liquid Water, especially when radar can not detect storm bottom and top due to the influence of radar scan strategy. In order to decrease the rate of false hail warning, it＇s very important to modify adaptive parameter, especially the height of the 0℃ and -20℃ environmental temperature in using Hail Detect Algorithm （HDA）.

关 键 词：强对流天气 冰雹 下击暴流 多普勒天气雷达 

分 类 号：P458.11[天文地球—大气科学及气象学]