Long Term Trend of Tropical Pacific Temperature under Global Warming

The tropical Pacific plays an important role in modulating the global climate. However, large discrepancies remain among the various estimates of the long-term trend in the tropical Pacific under global warming. Using multiple sea surface temperature (SST) and subsurface temperature datasets, this study investigates the long-term trend of SST in the tropical Pacific and the long-term trend of subsurface temperature in the equatorial Pacific based on the Theil-Sen trend estimation method. Our results indicate a cooling trend in the Pacific cold tongue region and a warming trend in the rest of the tropical Pacific under global warming. That is, the long-term trend of oceanic temperature has a La Niña-like pattern. Furthermore, this La Niña-like pattern in the tropical Pacific is induced by the cold tongue mode (CTM). A positive CTM is characterized by the cold temperature anomaly in the Pacific cold tongue region and the warm temperature anomaly in the rest of the tropical Pacific. Moreover, the time series of the CTM mainly exhibits a strong long-term trend, which is induced by the ocean dynamical processes in response to global warming. The La Niña-like pattern of the long-term trend of the SST and subsurface temperature in the equatorial Pacific indicates the different aspects of the CTM.