SIMULATION AND HINDCASTS OF TROPICAL PACIFIC-OCEAN INTERANNUAL VARIABILITY

A general circulation model of the tropical Pacific Ocean with a high resolution equatorial region is forced with observed winds from 1961 to 1993 to obtain a simulation of oceanic variability. Observed interannual sea surface temperature anomalies are reproduced well in the central equatorial Pacific, which is a region of strong variations in air-sea interaction. Combined principal oscillation pattern analysis of SST, heat content and zonal wind stress anomalies leads to a dominant interannual mode with a period of about 3 years. An empirical atmosphere model is constructed using the observed wind stress and the dominant simulated SST anomaly patterns. With the OGCM coupled to this statistical atmosphere, several hindcasts are made for the main recent ENSO events. Cold events are reproduced reasonably well, warm events less well: in particular, the 1982/83 hindcasts failed to produce a warming.