Western Pacific Oceanic Heat Content: A Better Predictor of La Ni�a Than of El Ni�o
Date
2018Author
Planton, Y.
Vialard, J.
Guilyardi, E.
Lengaigne, M.
Izumo, T.
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The western equatorial Pacific oceanic heat content (warm water volume in the west or WWVw) is the best El Ni�o-Southern Oscillation (ENSO) predictor beyond 1-year lead. Using observations and selected Coupled Model Intercomparison Project Phase 5 simulations, we show that a discharged WWVw in boreal fall is a better predictor of La Ni�a than a recharged WWVw for El Ni�o 13 months later, both in terms of occurrence and amplitude. These results are robust when considering the heat content across the entire equatorial Pacific (WWV) at shorter lead times, including all Coupled Model Intercomparison Project Phase 5 models or excluding Ni�o-Ni�a and Ni�a-Ni�o phase transitions. Suggested mechanisms for this asymmetry include (1) the negatively skewed WWVw distribution with stronger discharges related to stronger wind stress anomalies during El Ni�o and (2) the stronger positive Bjerknes feedback loop during El Ni�o. The possible role of stronger subseasonal wind variations during El Ni�o is also discussed.
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