江苏盐城8.17雷雨大风天气过程雷达回波特征分析

ANALYSES ON THE RADAR ECHO OF THE THUNDER STORM AND GALE IN JIANGSU YANCHENG ON AUGUST 17

本文分析了2005年8月17日江苏盐城地区的一次雷雨大风天气过程(简作8.17雷雨大风)的雷达回波特征。分析表明:贝湖东侧有较强的冷涡,高空槽前有西南急流存在,低层有冷锋锋区南压,本地受减弱缓慢南撤的副热带高压控制,850 hPa为暖湿气流控制;K指数、SI指数和θse都表明有较强的不稳定天气产生;在雷达回波特征上,具有强冷锋带状回波特征;风场上有明显的辐合;液态含水量值和一小时累积降水量有较好的指示作用。切变线和辐合区的存在是强回波得以维持和发展的主要原因。冷空气的入侵,冷暖空气交汇,是强对流天气爆发的直接原因。及时利用新一代天气雷达信息,进行预警信号的发布工作,取得了非常好的效果,并得到社会公众的认可。

This paper has analysed the radar echo of the thunder storm and gale happened in the region of Yancheng located north of Jiangsu province on August 17,2005 . Through the analysis ,we can find a strong cold air mass in the east of Baikal and the south-west-jet behind a low level trough . In the lower atmosphere the cold front passed toward south so that our region was effected by the weak subtropical anticyclone and at the level of 850mb the warm-wet current was dominant. The K index,the SI index and θse all indicated there would be stronger instable weather. The radar echo manifested features of the belt-shaped and upwind zone. The content of the vertically integrated liquid and the one hour precipitation were better indication . The existing of the shear line and the convergence area make sure that the strong echo maintained and developed . The direct reason that causes the strong convection weather breaking out were the inbreak of cold air and the confluence of cold and warm air.