Extended ENSO predictions using a fully coupled ocean-atmosphere model

Using a fully coupled global ocean-atmosphere general circulation model assimilating only sea surface temperature, the authors found for the first time that several El Nino-Southern Oscillation (ENSO) events over the past two decades can be predicted at lead times of up to 2 yr. The El Nino condition in the 1997/98 winter can be predicted to some extent up to about a 11/2-yr lead but with a weak intensity and large phase delay in the prediction of the onset of this exceptionally strong event. This is attributed to the influence of active and intensive stochastic westerly wind bursts during late 1996 to mid-1997, which are generally unpredictable at seasonal time scales. The cold signals in the 1984/85 and 1999/2000 winters during the peak phases of the past two long-lasting La Nina events are predicted well up to a 2-yr lead. Amazingly, the mild El Nino-like event of 2002/03 is also predicted well up to a 2-yr lead, suggesting a link between the prolonged El Nino and the tropical Pacific decadal variability. Seasonal climate anomalies over vast parts of the globe during specific ENSO years are also realistically predicted up to a 2-yr lead for the first time.