An exercise in forecasting loop current and eddy frontal positions in the Gulf of Mexico

As part of a model-evaluation exercise to forecast Loop Current and Loop Current eddy frontal positions in the Gulf of Mexico, the Princeton Regional Ocean Forecast System ( PROFS) is tested to forecast 14 4-week periods Aug/25/99-Sep/20/00, during which a powerful eddy, Eddy Juggernaut ( Eddy-J) separated from the Loop Current and propagated southwestward. To initialize each forecast, PROFS assimilates satellite sea surface height ( SSH) anomaly and temperature ( SST) by projecting them into subsurface density using a surface/subsurface correlation that is a function of the satellite SSH anomaly. The closest distances of the forecast fronts from seven fixed stations in the northern Gulf over a 4-week forecast horizon are then compared against frontal observations derived primarily from drifters. Model forecasts beat persistence and the major source of error is found to be due to the initial hindcast fields.