Global Ocean Nowcast/Forecast SST's from Multi-model Ensembles

Multiple global SST nowcasts/forecasts are now available from various ocean operational systems (OOS). It can also be safely assumed that these systems have complementary predictive skills. There is also now well-documented literature that shows combining multiple forecasts using simple combinations can help substantially increase accuracy (or reduce error) of such forecasts (Clemen, 1989, Galmarini et al., 2004). Daily global nowcast SST fields from five different OOS (HYCOM, FOAM, CFS, RTOFS & MERCATOR) are used for investigation of ensemble techniques. The employed techniques include weighted means, clustering algorithms (Hartigan, 1975; Arthur and Vassilivitski, 2006) and operational consensus forecasts (Woodcock & Engel, 2005). Preliminary results are presented and discussed along with their limitations. Other alternatives to building ensembles including forecasts from prior run cycles of the same OOS will also be considered.