2007年5月5—6日飑线天气过程分析

Analysis of a Strong Squall Line Weather Process from 5 to 6 May 2007

本文用多种气象资料对2007年5月5日午后到5月6日凌晨发生在山东半岛南部到浙江北部沿海地区的一次飑线天气过程的特征和成因进行了分析。发现这次飑线天气过程在高空西风槽、低层切变线和地面弱冷锋以及锋面上低压的共同作用下产生了中尺度对流系统(MCS),该地区有利的水汽、动力和大气层结条件使MCS中的雷暴群得以发展为飑线,并东移南压,产生了大范围的雷雨大风天气,其中的一个弓形回波对上海及长江三角洲产生了灾害性大风和雷雨天气。卫星云图、多普勒雷达资料很好地揭示了该飑线和弓形回波的发生、发展过程及其回波和风场的结构特点。而仅有浅层的水汽输送说明了本次强对流天气主要灾害为风灾。本文还指出了利用华东地区综合探测网积极主动地进行区域联防,及时发布强对流预警信息,可提高短时预警时效,有效发挥气象部门在防灾减灾中的作用。

Using several kinds of meteorological observations,the characteristics and causes of a long-lived squall line occurring in the coastal areas of East China(from the Shandong Peninsula to the northern part of Zhejiang coast) during the late afternoon of May 5 to the early morning of May 6 in 2007 were analyzed.It is found that a mesoscale convective system(MCS) developed as a result of the combination of a high-level trough,a low-level shear line,a weak surface cold front,and a low pressure system along the cold front.Abundant moisture,strong lifting,and high instability of the atmospheric environment made the thunderstorms along the MCS well-developed.A strong squall line embedded in the MCS moved from northwest to southeast and caused widely strong wind gusts over the East China region.One of the bow echoes in the MCS brought hazardous winds and thundershowers in Shanghai and the Yangtze River Delta region.Satellite images and WSR-88D Doppler weather radar products were used to illustrate the initiation and development process of the squall line and the bow echo,as well as some structural characteristics of the echoes and wind fields.The only low-level moisture transportation revealed that the main hazardous weather produced by the severe convection was strong wind.The paper also suggests that by using of the East China integrated observating network,it is possible to improve the leading time of severe weather warning,and joint watch for severe weather will be active and effective in the disaster prevention and mitigation.