超强台风“圣帕”引发温州类龙卷的特征分析

利用NCEP/NCAR 1°×1°6h再分析资料、多普勒天气雷达资料及FY-2C卫星TBB资料,分析了2007年8月18日23:10(北京时,下同)～23:20在0709号超强台风"圣帕(Sepat)"外围温州市龙港镇诱生类龙卷。诊断分析表明,类龙卷发生地所处环境特征为高层辐散、低层辐合、从低层一直延展到高层的强烈上升运动、超低空强垂直风切变等;雷达连续跟踪探测到气旋式速度存在由中层向低层发展的现象,该中气旋中伴有明显的相邻方位角速度切变,尽管没有满足龙卷涡旋特征(TVS)的所有指标,但强烈的旋转风在极短时间由高层向低层迅速发展下传,进而产生超级单体龙卷。

Analysis on a Severe Storm of Wenzhou Similar Tornado in The Outer-Region of the Super Typhoon ‘Sepat’

A similar tornado event during 23:10 to 23:20 on 18 August 2007 induced in Longgang of Wenzhou city in the peripheral of Super Typhoon ’Sepat’(0709) is analyzed using the NCEP/NCAR 1°×1° 6 h reanalysis data,Doppler radar data and TBB data of FY-2C satellite.The physical diagnosis shows that this event occurred in the environment characterized by such as upper-level divergence,lower-level convergence,strong upward motion extending from lower to upper levels,and strong vertical wind shear in the very low altitude.Doppler radar monitoring shows that a mesoscale cyclone appeared in Longgang town,40 km away from the radar station,associated with significantly adjacent azimuthal velocity shear,and the radar continuously tracked and detected the phenomenon of cyclonic speed developing from middle to lower levels.Although it had no indicators of the tornado vortex characteristics(TVS) from the radar observation,but the strong rotational wind rapidly developed and transported downward from upper to lower levels in a very short time,and it thus caused the supercell tornadogenesis.