CHARACTERISTICS ON INTERANNUAL VARIATIONS OF NORTH PACIFIC SST AND ITS RELATION TO EAST ASIA CLIMATE

The interannual variations of the monthly sea surface temperature (SST) in the North Pacific (including Equatorial East Pacific) during 1951-1980 are analysed by means of EOF method.The findings are:
(1) In the cold and warm ocean current areas, such as the North Pacific Current, the California Current and the Equatorial East Pacific areas, the convergence speeds are the fastest, while in the Kuroshio and the western part of the North Equatorial Current areas they are fast only in winter.
(2) The physical features of the first 3 eigenvectors are obvious.The first eigenvector shows that the SST values are high in the south and low in the north in the latitudinal distribution of the SST field.The warm current area, i.e.the northwestern part of the North Pacific is positive and the cold current area, i.e.the southeastern part of the North Pacific including the Eastern Equatorial Pacific is negative.The zero line of the 2nd eigenvector field runs from northeast to southwest, in the same direction as the 1st term.For the 3rd eigenvector field, the role of the Kuroshio area is striking.The sign of components of this eigenvector is negative in the north, the North Pacific Current area; on the contrary, the other 3 ocean current areas show positive.The Central Pacific is weakly negative.
(3) The characteristics of the annual variation of the monthly SST are obtained from analyses of time amplitude coefficients associated with eigenvectors.There are quasi-periodic oscillations of 5-6 years in the 1950's and early 1960's, while 2-3 years in the 1960's and 1970's.These characteristics affect the interannual variation of East Asia climate.