On the 30–60 Day Oscillation and the Prediction of El Niño

Abstract

The impact of intraseasonal variability on ENSO is studied in the context of the Zebiak and Cane coupled atmosphere?ocean model, and an idealized representation intraseasonal forcing. The effects of the parameterized forcing are examined in both simulation and forecast experiments, with similar results; that is, the intraseasonal variability generally plays a minor role in altering the model behavior. Though the uncertainties inherent in both the coupled model and the specified forcing must be kept in mind, the results support the hypothesis that intraseasonal variability is not an essential component of ENSO. At the same time, they present evidence of occasional sensitive periods or states of the coupled system in which intraseasonal forcing (and possibly other forcings) can indeed disrupt the future course of events.