Analysis for upper abnormal current in North Pacific without equatorial area
In this paper,using the combining complex empirical orthogonal function(CEOF) analysis,the dynamic statistic diagnosis about the upper abnormal circulation of the months of the year in North Pacific without equatorial area is carried out.It is done to compare with abnormal circulation in equatorial Pacific.Main results are discussed as follows: the upper abnormal circulation of North Pacific mainly occurs in the sea area(the key area)to the east and south of Japan Honshu,and only very small part of the North Pacific area is covered by the key area;with the exception of the key area is carried out,the abnormal circulation is not obvious.Although the squares of the first mode and the second mode to the whole anomaly in the key area are smaller than those in equatorial Pacific,their contribution are not small to the abnormal circulation in the key area above.In the sea area above,the first mode represents a pair of vortices in the trend of east northeast to west southwest with reverse rotation direction,that is a couple of anticyclone and cyclone;the form of the second mode also mainly represents some vortices.Both of the first and the second modes' time coefficients have two states,and the two modes' numeric values determine the strength of their deviation flow fields.The bigger the modes' numeric values are,the greater deviations' degrees are.The wavelet analysis shows that both of the two modes' time coefficients have interannual variations and interdecadal variations,clearly.The two modes above are caused by wind stress anomalies driving seawater near the western boundary,whose nature is ocean Rossby wave,which is different from Kelvin wave in equatorial Pacific,but the two waves have a close relation with the abnormal wind stress.