Features Of Decadal Variability And The Possible Mechanism Of Sea-air System In The Pacific

In this paper, Features of Decadal Variability and the Possible Mechanism of Sea-air system in the Pacific are investigated by using upper-ocean temperature , heat storage and wind stress data, The main results are as follows:The most pronounce decadal sign exists at about 160 meter in depth in the western Pacific. There are significant decadal abrupt changes in temperature from surface to deep in the subsurface at about 1980. With different depth in the subsurface ,there exist 4 types of abrupt change modes ,their generation is closely related to the decadal sign which originates from the east of North Pacific and propagates along the south-west subduct ion route.The subduct ion sign propagates toward the western tropical Pacif ic;and the decadal sign from the western tropical Pacific propagates toward north-east. They meet at about 160 meter in depth in subtropical Pacific. Hence ,the decadal sign from the center of North pacific is difficult to affect ENSO's decadal variability directly.The key region of the ENSO decadal variability is the western tropical South Pacific, where also possesses pronounce decadal variability. If a decadal positive temperature anomaly occurs in the eastern tropical Pacific, the atmospheric response excites a anticyclonic wind stress anomaly in the east of Australia, which will lead to generate a negative temperature anomaly in the western tropical South Pacific. The negative temperature sign can move to the mid tropical Pacific then propagates eastward the eastern tropical Pacific and change the original positive temperature anomaly. A similar evolution but with an opposite sign follows subsequently. The whole cycle for the ENSO decadal variability needs about 14 years. So, it is more likely the tropical processes themselves lead to ENSO decadal variability.