Spatial Modes of the Summer SST Anomaly in the North Pacific and Its Relationship with the Circulation Anomaly over East Asia

In terms of the NCEP/NCAR and British Meteorological Office monthly global sea surface temperature data, the dominant spatial modes of summer North Pacific SST anomaly (SSTA) since 1979 are examined. The relationship between the spatial variation of SSTA and East Asian circulation is investigated by the further analysis. Results show that there are two dominant modes for the summer North Pacific SSTA. When SST is higher (lower) than normal in the western Pacific from the tropical to Kuroshio region and lower (higher) in the southeastern Pacific, there are remarkable height anomalies to the south of Baikal, which is associated with divergence anomalies resulting from SSTA in the western Pacific. Anomalous ascending (descending) motions occur when SSTA is positive (negative) in the western Pacific and thereby anomalous descending (ascending) motions appear to the south of Baikal because of quality continuity. And it is helpful for the anticyclone to be enhanced (weaken) there.