江苏一次下击暴流过程致灾大风成因分析  

CAUSE ANALYSIS OF DISASTROUS GALE IN DOWNBURST EVENT IN JIANGSU

作　　者：禹梁玉 王啸华[1,2] 顾荣直 蒋启进 YU Liangyu;WANG Xiaohua;GU Rongzhi;JIANG Qijin(Jiangsu Meteorological Observatory,Nanjing 210000,China;Aviation meteorological data function and high-impact weather warning service laboratory,Yangzhou 225236,China)

机构地区：[1]江苏省气象台,江苏南京210000 [2]航空气象数据融合与高影响天气预警服务实验室,江苏扬州225236

出　　处：《热带气象学报》2021年第5期801-811,共11页Journal of Tropical Meteorology

基　　金：国家自然科学基金(U2142203);中国气象局预报员专项(CMAYBY2018-029);中国气象局预报员专项(CMAYBY2020-045)共同资助。

摘　　要：通过天气学分析方法和雷达回波特征分析方法对发生在江苏沿淮地区一次下击暴流事件的环境条件、地面要素场特征和六次风暴单体造成的下击暴流过程进行了分析,并探讨12级致灾大风的可能成因,探寻具有较大预警提前量的下击暴流大风预警指标。结果表明:此次下击暴流事件是在具有前倾槽结构的弱风速垂直切变环境条件下由脉冲风暴等孤立对流系统的强冷性下沉气流所造成的。地面灾害性大风发生前20~40min可在风暴单体外围识别出缓慢向外扩散的环形阵风锋,该环形阵风锋从雷暴大风预警业务角度来说可认为是下击暴流产生地面大风的“先兆信号”;风暴单体的反射率因子核、风暴质心高度以及垂直积分液态水含量(VIL)值在地面8级以上强风发生前约20min显示出持续下降的特征。下击暴流造成的致灾大风可能是由于同时发生的两个风暴单体下击暴流辐散气流的同向叠加、强变压风、强密度流和次级环流的加强等共同作用所导致。To explore a downburst gale early warning index with more time leading early warning,the present study analyzed the environmental conditions,ground element field characteristics and the downburst process caused by six storm cells in a downburst event along the Huaihe River in Jiangsu Province and discussed the possible causes of disastrous gale by conducting synoptic analysis and radar echo characteristic analysis.The results show that the downburst was caused by the strong cold downdraft of the isolated convective systems,such as the pulse storms,which were triggered under the condition of weak vertical wind shear with a forward-inclined trough structure.The annular gust front with slow outward diffusion could be identified at the periphery of the storm cell 20~40 minutes before the occurrence of the ground disastrous gale,which could be regarded as the precursor signal of thunderstorm winds.The reflectivity factor core,storm centroid height and vertical integrated liquid water content of storm monomer showed the characteristics of continuous decline about 20 minutes before the occurrence of strong winds.The disastrous gale may be caused by the simultaneous superposition of the downburst and divergent air flow under the two storm cells,the strong variable pressure wind,the strong density current and the strengthening of the secondary circulation.

关 键 词：下击暴流 致灾大风 弱环境风垂直切变 环形阵风锋 垂直积分液态水含量 

分 类 号：P445[天文地球—大气科学及气象学]