THE ENSO EVENTS IN THE TROPICAL PACIFIC AND DIPOLE EVENTS IN THE INDIAN OCEAN

A curved surface （close to that of the thermocline as defined by 20 ℃）of climatically maximum sea-temperature anomaly was created at the subsurface of the tropical Pacific and Indian Ocean, based on which the evolving sea-temperature anomaly at this curved surface from 1960 to 2000 was statistically analyzed. It is noted that the evolving sea temperature anomaly at this curved surface can be better analyzed than the evolving sea surface one. For example, during the ENSO event in the tropical Pacific, the sea-temperature anomaly signals travel counter-clockwise within the range of 10 degree North and South latitudes along the equator, and while traveling, the signals change in intensity or even type. If Dipole in the tropical Indian Ocean, which stays at the curved surface of maximum sea-temperature anomaly is analyzed, the sea-temperature anomalies of the eastern and western Indian Ocean would be negatively correlated in statistical sense (Dipole in real physical sense), which is unlike the sea surface temperature anomaly based analysis that demonstrates that the inter-annual positive and negative changes only occur on the gradients of the western and eastern temperature anomalies. A further analysis shows that the development of ENSO and Dipole features time delay statistically, with the sea-temperature anomaly in the eastern equatorial Pacific changing earlier (by three months or so). And the linkage between these two changes is a pair of coupled evolving Walker circulations that move reversely in the equatorial Pacific and Indian oceans.