2007年7月3日苏皖龙卷风成因初步分析

利用常规探测资料,ncep1×1再分析资料,通过江苏省加密自动气象站、FY2C红外卫星云图和南京多普勒雷达观测资料及产品追踪2007年7月3日下午发生在安徽天长仁和镇和江苏高邮天山镇的龙卷风天气过程发现:在江淮梅雨期内,大气层结不稳定,当低层及地面有明显的辐合时,冷空气的到来使环境水平风向风速的垂直切变增大,使得已经发展起来的风暴可能进一步发展而成为龙卷风。在多普勒雷达基本反射率图上,飑线形势的带状回波演变为弓形,预示着增加的灾害潜势;中尺度气旋与龙卷风有密切关系;比较浅薄的中等强度的垂直风切变增强变厚将使得对流进一步演变为深对流,会引发小尺度的中气旋。

Preliminary Analysis on the Cause of Tornadoe on July 3rd,2007

Based on the conventional observation data,ncep1×1 reanalysis data,the observation data and products from the intensive automatic meteorological station of Jiangsu,FY2C infrared satellite nephogram and Doppler radar of Nanjing and product tracing,tornado weather process occurred in Renhe Town,Tianchang County of Anhui Province and Tianshan Town,Gaoyou County of Jiangsu Province in the afternoon of July 3rd,2007 was analyzed.The aerosphere was not stable in Jiang-Huai Meiyu period.When obvious convergence existed in low layer and on the ground,the vertical shear of the environmental horizontal wind speed increased with the coming of cold air.Thus the developed wind storm might be developed further to form a tornado.On the basic reflectivity figure of Doppler radar,the band echo of squall line changed into bow echo,indicating the increased disaster potential.Middle-scale cyclone was closely related with tornado.The increased and thickened vertical wind shear with moderate intensity would change thinner convection into deep convection and cause small-scale mesocyclone.