COUPLING PATTERNS OF AIR-SEA INTERACTION AT MIDDLE & LOWER LATITUDES AND THEIR INTERDECADAL OSCILLATION

Diagnostic studies have been done of the seasonal and interdecadal variations of the coupling patterns for the air-sea interactions in the northern pacific region.by using 500-hpa geotential hight field of the Northern Hemisphere and monthly mean SST field of northern Pacific Ocean(1951～1995) and with the aid of the Singular Value Decomposition(SVD) technique.The results show that:(1) The distribution patterns of SVD,which link with the E1 Nino(or La Nina) events,are important in the interaction between the atmosphere and ocean while the atmosphere,coupling with it ,varies like the PNA teleconnection does.The coupling of airsea interactions is the highest in the winter(January) ,specifically linking the E1 Nino event with the PNA pattern in the geopotential height field.Of the four seasons,summer has the poorest coupling when the 500-hPa geopotential height field corresponding to the La nina event displays patterns similar to the East Asian-Pacific one(PJ).The spring and autumn are both transitional and the coupling is less thght in the autumn than in the spring.(2) Significant changes have taken place around 1976 in the pattern of air-sea coupling,with the year‘s winter having intensified PNA pattern of 500-hPa winter geopotential height field,deepened Aleutian low that moves southeast and the summer following it having outstanding PJ pattern of 500-hPa geopotential height field,which is not so before 1976.