North Tropical Atlantic SST as a Trigger of El Niño

Despite decades of efforts in understanding and predicting the El Niño-Southern Oscillation (ENSO), forecasting the onset of an El Niño event remains a challenge. Here, we show evidences that the sea surface temperature (SST) in the North Tropical Atlantic (NTA) can serve as an important trigger for El Niño/La Niña events. Through a pair of cyclonic and anticyclonic flows along the Pacific Intertropical Convergence Zone (ITCZ), the positive NTA produces equatorial easterlies over the western Pacific during boreal spring to summer, which may trigger a negative phase of ENSO during the subsequent boreal winter. It is also suggested here that this process is closely related to the development of a new type of El Niño1,2, whose SST action center is located over the central Pacific. This study has important implication for predicting different types of El Niño events using the Atlantic precursors.