干旱气候背景下塔尔湖暴雨形成机理诊断分析

The Diagnostic Analysis on Torrential Rain of Taer Lake in the Background of Drought Climate

利用常规气象资料和自动站资料,对2009年8月18日发生在塔尔湖地区1次暴雨过程进行分析,结果表明:⑴整个前汛期副高位置偏西,是造成巴彦淖尔市干旱的直接原因。⑵副高东退,东高西低形势建立,是塔尔湖暴雨形成的必要条件。⑶500hPa短波槽前正涡度区与700hPa暖切变区、地面暖锋切变区在阴山山脉南麓罕乌拉沟喇叭口地形上空垂直叠置,是产生塔尔湖暴雨的动力抬升条件,也是其形成的触发机制。⑷700hPa贝湖冷涡维持,西南暖涡北抬,两涡在阴山南北相遇的辐合流场建立,为塔尔湖暴雨提供了水汽和冷空气条件,也是干旱年份巴彦淖尔市暴雨预报的重要着眼点。

Based on the conventional data and automatic weather station data,a diagnostic analysis on torrential rain weather process on August 18,2009 around Taer lake was carried.The results showed that（1）the location of subtropic high which is partial to west in the prophase of flood season was the main reason that leaded Bayannor drought.（2）The recession of subtropic high and the situation of east high west low was established were the the necessary conditions of torrential rain occurrence.（3）The positive vortex in the front of the short wave trough in the 500hpa,the warm shear area of 700hpa,and the warm front shear area in the southern of the shady hill vertically stacked,and it＇s the lifting condition of the torrential rain occurence,and it＇s also the trigger mechanism.（4） The cold vortex of Baikal Lake was maintained in 700hpa,and the southwest warm vortex was lifted to north,two vortexes were formed in the field of convergence in the south and north of Yinshan mountain.It offered the condition of vapor and cold air for the torrential rain,and it is also the important focus of forecasting in droughty year.