【摘要】 对 1999年 4月 2 1～ 2 6日出现在我国西北地区的一次区域性强寒潮过程 ,从天气事实、天气成因及动力诊断等方面进行了分析探讨。结果表明 ,环流经纬向型的调整是寒潮酝酿和爆发的直接原因。上游美洲大槽加深造成的下传波能为寒潮酝酿提供了能量基础 ,西风急流的南北大幅摆动使高度槽加深和高空锋区增强 ,这二者是寒潮生成的间接原因。冷气团中存在的上升运动 ,使冷空气影响的范围和强度增大。另外 ,伴随寒潮出现的强降温、大风、沙尘暴等其他天气现象与前期西北区上空大气普遍增温密切相关更多还原

【Abstract】 In this paper,a strong regional cold wave weather process occurred on 21-26th.April 1999 in Northwest China is studied from the synoptic fact,formation and dynamics diagnosis.The results show that the adjustment of circulation pattern,is the direct outcome of the cold wave brewing and outbread.The down transport wave energy caused by downstream deepness of trough in American continent provides energy for its;the swaying of westerly jet deepens the trough and enhances the upper cold front,which are indirect causes of the cold wave outbread.The ascending motion in cle air mass enlarges the intensity of cold air incessantly.In addition,the strong detemperature,gale,sandstorm,which are due to cold wave,are closely relative to the upper air general anatherm in Nothwest China at prior period.更多还原