东北三江流域夏季旱涝基本特征分析

用美国国家环境预报中心 (NCEP) 再分析的高空月平均资料以及中国范围内160个测站的月降水量资料, 对夏季我国东北地区的降水进行分型并分析其环流形势.结果表明, 我国东北三江地区夏季多雨年和少雨年的环流形势存在明显的差异, 1998年夏季属于典型的多雨年; 鄂霍茨克海阻塞高压的出现和发展, 是造成嫩江、松花江流域夏季降水异常偏多的主要原因; 对流层低层水汽通量辐合加强, 是东北地区降水的重要水汽条件; 12月份或冬季的极涡强度指数与次年8月份或夏季我国东北地区的降水存在密切的正相关, 这种关系可以作为预测我国东北地区夏季持续强降水的一个信号.

Research on the Features of Summer Rainfall in Northeast China

By using the monthly averaged upper air reanalysis data of NCEP and the monthly precipitation data of 160 stations over China, analysis is made on the summer circulation and rainfall patterns in Northeast China. The results indicate that there exists obvious difference in circulation between wet and dry years in Northeast China in summer and the circulation pattern of the summer in 1998 was similar to that of the wet year. The development of the Okhotsk blocking high was the main reason of the heavy precipitation in the Songhuajiang River and the Nenjiang River basins. The enhancement of moisture flux convergence in lower layers of troposphere is a favorable condition for rainfall in Northeast China. It is also found that there exists closely positive correlation between the polar vortex intensity index in December or winter and the precipitation in Northwest China in the subsequent August or summer, which can be regarded as a signal for the precipitation in Northeast China.[WT5BZ] [WT5HZ]