Predictive Skill of Statistical and Dynamical Climate Models in SST Forecasts during the 1997—98 El Niño Episode and the 1998 La Niña Onset

Abstract Critical reviews of forecasts of ENSO conditions, based on a set of 15 dynamical and statistical models, are given for the 1997—98 El Nino event and the initial stages of the 1998—99 La Nina. While many of the models forecasted some degree of warming one to two seasons prior to the onset of the El Nino in boreal spring of 1997, none predicted its strength until the event was already becoming very strong in late spring. Neither the dynamical nor the statistical models, as groups, performed significantly better than the other during this episode. The best performing statistical models and dynamical models forecast SST anomalies of about +1°C (vs 2.5°—3° observed) in the Nino 3.4 region prior to any observed positive anomalies. The most comprehensive dynamical models performed better than the simple dynamical models. Once the El Nino had developed in mid-1997, a larger set of models was able to forecast its peak in late 1997 and dissipation and reversal to cold conditions in late spring/early summer...