大连市两次暴雨过程特征分析

Characteristic analysis of two rainstorm processes in Dalian city

运用常规天气资料,并根据地面自动站和多普勒雷达等资料,综合分析了2007年8月10—12日和2011年8月28日大连地区暴雨天气过程。结果表明,稳定的高压坝保证了暴雨落区在大连和降水时间的持续。地面中尺度气旋和台风减弱的热带低压是产生暴雨的动力条件。低空急流起着输送水气和能量的作用,在急流最大风速中心的前方有明显的水气辐合和强上升运动,对于强对流活动的连续发展是有利的,在急流的左前方是正切变涡度区,有利于对流活动发生。强对流发生区与暖舌对应。雷达回波的列车效应现象,印证了高压坝的存在。

The heavy storm weather processes in Dalian region on Aug.10-12 nd,2007 and Aug.28 th,2011 were discussed in terms of the data from general weather map and automatic weather observation station as well as Doppler radar.The results shows that the steady high-pressure barrier ensures the rainstorm falling areas in Dalian and the duration of the rainstorms.The surface mesoscale cyclone and the tropical depression with weakened typhoon is the dynamic conditions causing the heavy rainfall process.The low-level jet stream is mainly for the purpose on water vapor and the energy transportation.There are obvious water vapor convergence and strong ascending motion in front of the maximum wind speed center of the jet stream,which is beneficial to the continuous development of strong convection.In the left front of the jet stream is the positive vorticity area which is good for the appearance of the convective activities.The strong convection zone corresponds to the warm tongue.The'train effect'phenomenon of radar echo confirms the existence of high-pressure barrier.