一次长历时特大暴雨多普勒雷达中尺度分析  

Mesoscale Analysis on a Long-Lasting Torrential Rainfall Event by Doppler Radar

作　　者：张家国[1] 岳阳[1] 牛淑贞 邵木兰[1] 

机构地区：[1]武汉中心气象台 [2]河南省气象台

出　　处：《气象》2010年第4期21-26,共6页Meteorological Monthly

基　　金：武汉区域气象中心科技发展基金项目"灾害性暴雨多普勒雷达观测研究"QY-Z-200904资助

摘　　要：2008年7月22日湖北省襄樊市出现了一次长历时的特大暴雨过程,9小时内降水量301 mm,占年平均降水量的三分之一,为当地有气象记录以来最大、最强的一次降水过程。利用多普勒雷达资料等对这次特大暴雨的回波结构特征、中尺度系统活动和地形作用进行了分析。结果表明:(1)在低涡、切变线共同作用下,影响襄樊地区特大暴雨的回波系统有两个,一是稳定维持在鄂西北地区的切变线带状降水回波,二是低涡东北侧发展的具有螺旋回波带结构的涡旋回波,两者构成涡带结合型回波结构形态。在涡带结合处,对流回波的不断新生、向北移动导致襄樊地区持续性的强降水。(2)襄樊特大暴雨过程的发生与其北部115 km处的一支东北风中尺度超低空急流的建立,及其南部低涡东侧强偏南暖湿气流的向北发展有密切关系。由于襄樊西侧武当山的屏障作用,超低空东北急流折向东南,与偏南暖湿气流在静止锋附近形成中尺度气旋性辐合上升运动。两支急流的维持对襄樊附近持续性的辐合上升运动起到关键作用。On July 22, 2008, a long-lasting torrential rainfall envent occurred in Xiangfan , Hubei Province. Its accumulated rainfall only for 9 hours was 301 mm, as much as 1/3 of the normal yearly rainfall, which was the strongest rainfall according to meteorological records of Xiangfan. The echo structure characteris- tics, mesoscale system activity and the topographic forcing were analyzed by the Doppler radar data. The results show as follows. （1） There are two echo systems affecting torrential rainfall of Xiangfan, one is the shear line-banded echo which maintains stably in northwestern Hubei, the other is the vortex echo with a spiral-echo-belt structure. Both together form a vortex-band combined echo structure. In the conjunction area, convective echoes emerge and move to the north continually, resulting in the Xiangfan long-lasting strong rainfall. （2） The Xiangfan rainstorm event has a close relationship to the established super-low-lev- el northeasterly jet, and the strong warm-moist southwesterly moving to the north. Because of the Wu- dang mountain＇s barrier located in the west side of Xiangfan, the super-LLJ turns to southeast, and forms the mesoscale cyclone convergence with the warm-moist southwesterly nearby the stationary front. The two stranded LLJs play a key role in sustaining convergence near Xiangfan. Key words： torrential rain, low-level jet （LLJ）, mesoscale systems, topography

关 键 词：特大暴雨 低空急流 中尺度系统 地形 

分 类 号：P458.121.1[天文地球—大气科学及气象学]