春季北太平洋关键海域流场异常分析及其与夏季华北降水关系初探

Analysis of Abnormal Spring Current in the Key Area of North Pacific and the Relationship with Summer Precipitation in North China

本文采用复EOF法,对春季北太平洋关键海域的上层洋流异常做了统计动力诊断,用以考察上层流场的年际和年代际变化,并简单讨论了其与夏季华北降水异常的关系。主要结论有:复EOF第一模态中,上层洋流异常表现为东北至西南走向的涡旋偶;时间系数有明显的年际和年代际变化,且与华北夏季降水的年际和年代际变化周期相似;在年代际尺度确定时,辐角的两个状态较好地对应于华北夏季降水的多寡;海洋西边界附近海水流动的异常是风应力异常所致,其性质属海洋Rossby波。

In this paper, using CEOF analysis, the dynamic statistic diagnosis of abnormal upper current of springtime in the key area of North Pacific is done to discuss the inter-decadal and decadal variations of upper current and discover the relationship of summer precipitation in North China. The results are: In the first mode of CEOF, the abnormal upper current represents as a pair of vortices in the trend of EN to WS;there is obvious inter-decadal and decadal variation of time series, which is similar with the summer precipitation in North China;When decadal scale is identified, ampli-tudes’ two states are corresponding to the abnormal summer precipitation in North China;The abnormal of space field is caused by wind stress anomalies driving seawater off west coast, whose nature is ocean Rossby wave anomalies.