1998年汛期嫩江松花江流域大暴雨成因分析

An Analysis of Macro scale Circulation Characteristics and Synoptic Scale System with the Storm Rainfall Occuring in the Nenjiang-SonghuaJiang River Basin during 1998 Flood Period

分析了 1 998年汛期嫩江、松花江流域大暴雨形成的大尺度环流异常特征 ,指出东亚阻塞高压持续强盛位置偏西 ,乌拉尔山到西西伯利亚维持长波高压脊和西太平洋副热带高压与东亚阻高在 1 30°E附近同位相叠加是形成 1 998年汛期嫩江、松花江流域大暴雨的大尺度环流主要特征。它们为大暴雨的形成提供了优越的大尺度环流背景。频繁活动的东北冷涡是在这一大尺度环流背景下形成大暴雨的天气尺度系统。进一步分析了东北冷涡生成维持的环流条件和活动特征 。

After analyzing the macro scale circulation characteristics favourable to the storm rainfall in the Nenjiang-Songhuajiang River basin during 1998 flood period,It′s found that the East Asia blocking high is persistently strong and has a westward position.A longwave pressure ridge maintains between Ural and West Siberian region,and the West Pacific subtropical high and the East Asia blocking high superimpose each other in 130°E.The stable northeast cold vortex is a main reason leading to the storm rainfall in the Nenjiang river and the Songhuajiang river basin in 1998 summer.