STRUCTURE AND PREDICTABILITY OF THE EL-NINO SOUTHERN OSCILLATION PHENOMENON IN A COUPLED OCEAN ATMOSPHERE GENERAL-CIRCULATION MODEL

The space-time structure and predictability of the El Nino/Southern Os cillation (ENSO) phenomenon was investigated. Two comprehensive datase ts were analyzed by means of an advanced statistical method, one based on observational data and the other on data derived from an extended- range integration performed with a coupled ocean-atmosphere general ci rculation model. It is shown that a considerable portion of the ENSO-r elated low-frequency climate variability in both datasets is associate d with a cycle involving slow propagation in the equatorial oceanic he at content and the surface wind field. The existence of this cycle imp lies the possibility of climate predictions in the tropics up to lead times of about one year. This is shown by conducting an ensemble of pr edictions with our coupled general circulation model. For the first ti me a coupled model of this type was successfully applied to ENSO predi ctions.