Previous studies have indicated that boreal winter-to-spring sea surface temperature anomalies (SSTA)
over the tropical Atlantic or Indian Ocean can trigger the central-Pacific (CP) type of ENSO in the following winter due to
winds over the western Pacific. Here, with the aid of observational data and CMIP5 model simulations, we demonstrate
that the ability of the winter-to-spring north tropical Atlantic (NTA) SSTA or Indian Ocean Basin (IOB) mode to initiate
CP ENSO events in the following winter may strongly depend on each other. Most warming events of the IOB and NTA,
which are followed by CP La Niña events, are concomitant. The synergistic effect of the IOB and NTA SSTA may produce
greater CP ENSO events in the subsequent winter via Walker circulation adjustments. The impacts between warming and
cooling events of the IOB and NTA SSTA are asymmetric. IOB and NTA warmings appear to contribute to the subsequent
CP La Niña development, which is much greater than IOB and NTA cooling contributing to CP El Niño. Overall,
a combination of the IOB and NTA SSTA precursors may improve predictions of La Niña events.

Indian Ocean; North Atlantic Ocean; Atmosphere-ocean interaction; ENSO; Climate models; Interannual variability