Ensembles of tier-2 seasonal forecasts made with the NASA Seasonal-to-Interannual Prediction Project (NSIPP-1) atmospheric general circulation model (AGCM) are examined in order to assess the impact of uncertainties in the SST forecasts. This includes a comparison of AGCM forecasts that utilize SST from the NSIPP tier-1 coupled model forecasts with those that utilize the IRI/NCEP SST forecasts.

The NSIPP-1 AGCM forecasts are validated against the NCEP/NCAR reanalysis and against hindcasts with the same AGCM that utilize observed SST. An attempt is made to distinguish errors in the AGCM forecasts resulting from an incorrect SST forecast from uncertainties due to atmospheric noise and AGCM deficiencies. Results will be presented to show those regions of the planet that have the most to gain from an improvement in the SST forecasts.