Interdecadal Changing Relationship Between Equatorial Western And Eastern Pacific Variabilities As Well As Its Possible Relation To The Surface Air Temperature/Rainfall Anomalies In China

Using NCEP/NCAR 40-year reanalysis, GISST2.3b data-set, CRU South Oscillation Index along with in situ the 160 station data of surface air temperature/ rainfall records in China, the inter-decadal variations in the relationship between equatorial Western and Eastern Pacific variabilities are examined. The possible relations to the surface air temperature/rainfall in China are also investigated. Results indicate that there exist noticeable variations in the correlations of equatorial Western Pacific SSTA with SOI / NINO3 SSTA from decade to decade; the WPI-SOI correlation shows stronger inter-decadal changes in the boreal spring and the winter seasons in the recent fifty years. When the WPI- SOI correlation is weak and the West Pacific SST warmer (colder), a anomalous anticyclonic (cyclonic) circulation is found in the lower troposphere over northern equatorial western Pacific. This anomalous circulation is not in favor of maintaining a significant correlation between the West Pacific SST and ENSO. The ve>tical structure of such a circulation is found to be quasi-barotropic in northern spring and winter seasons. The correlation between WPI and the surface air temperature/rainfall in China is found to be weak when the correlation between WPI and SOI is strong in boreal spring and the winter. However, during boreal summer and fall seasons, the correlation between WPI and the rainfall in China is stronger when SOI-WPI correlation is higher.