河西走廊一次大雨天气诊断分析

对2009年8月18日发生在甘肃省河西走廊中部区域性大雨从天气形势、物理量场、水汽条件、卫星云图特征进行了综合分析,发现500 hPa巴尔喀什湖至新西伯利亚阻高的发展使得脊前冷槽南压加强,为这次区域性大雨形成提供了冷空气来源,副热带高压明显西升北抬为大雨形成提供了充足的水汽来源;700 hPa低空低涡的辐合为大雨产生提供了必要的上升运动,并促使对流不稳定层结的产生和发展。同时发现,中低层不稳定能量触发,在大尺度锋面降水云系中产生中尺度对流云团活动,是造成局地雨强较大的主要原因。高低空螺旋度"上负下正"的配置,对强降水的预测和落区有良好的指示作用。

Diagnosis of a Heavy Rain Occurred in the Hexi Corridor

The regional heavy rain occurred in the middle of Hexi Corridor on August 18 2009 was analyzed from the synoptic situation,physical quantity fields,water vapor conditions and satellite image's features.Results show that the development of 500 hPa blocking high from Balkhash Lake to Novosibirsk made the cold trough before the ridge strengthen and extend south,and it provided the cold air for this regional heavy rain.The western and northern extension of the subtropical high provided adequate water vapor for ...