In the east Pacific, the sea level was below average in 1996 but rose to become almost half a meter above average after the El Nino onset. Monthly stresses and SST anomalies for the same times are also shown. The ocean model has lower resolution in the extratropics but higher resolution in the equatorial region in order to resolve ocean baroclinic waves and processes which are tightly trapped to the equator. Three times per week the coupled model is integrated forward for 6 months. This creates an ensemble of 12 to 15 members each month.
Full coupling is applied between the atmosphere and ocean.
Because of model error, a drift occurs after coupling which is not small compared with the size of the signal being predicted. This drift is subtracted from the model fields once the integration is complete. Various forecast products are generated, showing both SST anomalies and the predicted atmosphere response. As an example of our Nino-3 forecasts, this plume diagram shows the ensemble of forecasts initiated over an extended period from November 1996 to April 1997. References Smith, N.,J.E. Blomley and G. Meyers.