Potential Impact of Winter-Spring North Atlantic Tripole SSTAs on the Following Autumn-Winter El Nino-Southern Oscillation: Bridging Role of the Tibetan Plateau

Sea surface temperature anomalies (SSTAs) over the North Atlantic could stimulate the El Nino-Southern Oscillation (ENSO) events through regulating the tropical and mid-latitude atmospheric circulations. Whether the Tibetan Plateau (TP) play an important bridging role in the mid-latitude pathway has been rarely considered. Observational analysis and model simulations show that the spring TP surface wind speed dipole mode forced by the winter-spring North Atlantic tripole SSTAs can induce surface zonal wind anomalies over the equatorial western Pacific from April to June through the Indo-Pacific gearing process, favoring the occurrence of subsequent autumn-winter ENSO events through the Bjerknes feedback. Moreover, a flattened TP will obviously weaken the atmospheric and oceanic responses associated with ENSO development to the North Atlantic tripole SSTAs forcing. Quantitatively, the TP's bridging effect accounts for about 38% proportion in the above process. Our finding provides a new insight in understanding the mid-latitude pathway.