大连大暴雨天气过程个例分析

Analysis of a Heavy Rainfall Event in Dalian

利用常规资料以及卫星、雷达、自动站等探测资料对2004年8月27-28日大连地区出现的局地暴雨、大暴雨天气进行分析,探讨此次大暴雨过程的特征与成因。此次大暴雨过程是在稳定的大尺度环流形势下,由3次中小尺度系统直接导致的。其中,副高稳定、东部高压脊加强少动是产生这场大暴雨的基础;同时在高空槽前正涡度平流的作用下,对流层中低层出现明显的降压,产生强烈上升运动,低层暖湿气流抬升促使对流不稳定能量爆发形成局地强对流和暴雨。

In August 27 -28, 2004, a local rainstorm occurred in Dalian, along with strong wind, caused severe damages. The characteristics and forming causes of this rainstorm is studied through the analysis of daily observation data and detecting data from satellites, radars and automatic stations. It is found that this rainstorm was induced directly by three meso-scale and small-scale systems under the condition of steady large-scale circulation. The basic causes of this rainstorm were the steady western Pacific subtropical hight and the stable and strengthening high pressure ridge in the east; meanwhile, caused by high-level front positive vorticity advection, the pressure of the middle and lower troposphere dropped resulted in drastic climbing-up of the air current. The riseing of the warm and humid current in the lower atmosphare contributed to the bursting of convective unsteady energy, and caused the local strong convection and the rainstorm.