COLA Report 10
Experimental Multi-Season ENSO Predictions with an Anomaly Coupled General Circulation Model
Zhengxin Zhu and Edwin K. Schneider
May 1995
Abstract
We examine multi-season El Niño and Southern Oscillation (ENSO) predictions by using an
anomaly coupled ocean-atmosphere general circulation model. Uncoupled integrations of the
atmosphere and ocean models were first conducted to obtain the model climatologies of sea surface
temperature (SST), wind stress and heat flux. Results of the uncoupled runs show that the models
are capable of simulating realistic interannual variability in the equatorial region when observed
boundary conditions are specified. Some discrepancies between the simulated anomalies and
observations were also found. A scheme which assimilates the observed wind stress and SST
anomalies was used to form the ocean initial conditions.
Two sets of hindcast predictions were carried out, each containing twelve one-year forecasts. In the
second set a simple modification to the wind stress anomalies was applied in order to adjust the
coupling strength. The results of the experimental forecasts show that the coupled system has an
ability to predict the SST anomalies in the tropical Pacific with a lead time of up to two seasons.
In the strong El Niño years of 1982 and 1983, the hindcasts were skillful up to one year lead time.
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last update: 24 May 1995
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