Interdecadal Changing Interaction Between Tropical Pacific And Indian Ocean And Possible Mechanisms

Using NECP/NCAR reanalysis.Gisst2.3b data-set, the inter-decadal variations in the relationship between the tropical Pacific and Indian Ocean inter-annual anomalies are examined. Results indicate that there exist noticeable variation in the relations of the tropical Pacific SSTA and Indian Ocean SSTA from decade to decade. During 1950~1976/1977,The Walker Circulation over the tropical Pacific and the vertical Zonal monsoon circulation over the tropical Indian Ocean coupled at the Oceanic Continent ,the same period when El nino occurs, the anomaly of the West wind over the tropical Pacific can correlate with the departure of East wind over the tropical Indian Ocean through the two coupled vertical zonal circulation. But after 1976/1977,the updraft of the Walker circulation moved eastward .locating at the north of Australia .therefore the two vertical zonal circulation couldn't coupled ,and the anomaly of west wind and the departure of east wind couldn't geared. In the result .the signal of ENSO decreased in Indian Ocean after 1976/1977. Seasonal reanalysis indicate that, in winter .the correlation between the tropical Pacific and the tropical Indian Ocean is found to be weak after 1976/1977,but, in summer the same correlation is higher.