1998年夏季嫩江和松花江流域东北冷涡暴雨的成因分析

A COMPOSITE DIAGNOSTIC STUDY OF HEAVY RAIN CAUSED BY THE NORTHEAST COLD VORTEX OVER SONGHUAJIANG-NENJIANG RIVER BASIN IN SUMMER OF 1998

选择了 1 998年 9例典型的松嫩流域东北冷涡暴雨过程进行诊断分析。结果表明 ,东亚阻高、西太平洋副高和东北冷涡以及它们在强度和位置上的最佳配置构成了 1 998年松嫩流域持续性暴雨的大尺度环流背景。亚洲季风诸系统 (南亚季风 ,副热带季风 )的水汽输送也是大范围强降水频繁出现的主要原因 ,并且是与一般冷涡降水的最根本区别。冷涡系统自身独特的水平和垂直结构特征导致暴雨中心主要发生在系统中心以东大约 6个经距的范围内 ,而不是出现在冷涡中心附近及其以西地区。

Nine typical heavy rain events caused by the northeast cold vortex over Songhuajiang Nenjiang basin in China have been chosen and their composite of physical variables were also done. The results show that the blocking high over East Asia, the west Pacific subtropical high, the northeast cold vortex and summer monsoon moisture transportation play quite important roles in the persistent heavy rain over the Songhuajiang Nenjiang region. The special horizontal and vertical structures of the cold vortex itself result in the heavy rain mainly occurring to the east of the cold vortex center.