梅雨锋引发的“03.7”特大暴雨雷达回波分析

利用常德雷达站多普勒天气雷达资料及其它资料分析了2003年7月7-11日特大暴雨天气过程的天气形势、雷达回波特征及中小尺度系统.雷达回波经历了初始、积层混合云、带状回波、积层混合云减弱消失阶段.回波单体始终自西南向东北方向移动,回波整体先由西北向东南,后北抬并移出湖南.降水回波属于低质心降水回波,"列车效应"是造成特大暴雨的主要回波特征,"列车效应"由有组织的中-γ尺度回波单体不断生消形成.多普勒速度图上,短时出现了"逆风区"等回波特征,由对流层中层不连续中小尺度大风核造成有组织的次级环流,可能是"列车效应"形成和维持的主要原因.谱宽图上,谱宽值各层十分均匀,表明强降水长时间维持的主要原因在于上下层环境风始终处于稳定状态.

Analysis on Doppler Radar Data of "03.7" Super Heavy Rain Caused by Meiyu-front

Using the Doppler radar data in Changde, Hunan Province and other conventional m eteorological and radar data, the synoptic situation and meso scale system feat ures of a super heavy rain in Hunan province caused by Meiyu front were analyze d. Results show that, the echoes experienced the stages of initial genesis, merg ing, helix band, merging, weakening and decay. The echo cells moved from southw est to northeast all the time, but the full echoes moved from northwest to south east firstly, then moved out from north of Hunan province. The center of echo is low. The train effect is the major character of this event. Even though the inv erse wind regions in the imagery of velocity, the well organized secondary cir culation caused by discontinuous meso scale jet core at the middle level of trop osphere may be the main reason to form and sustain the train effect. The spectra l width is very homogeneous at all levels. This indicates that the stable jet at middle level is the major reason of the long duration of the event.