An experimental real-time ocean nowcast/forecast system has been developed for the Intra America Seas (IASNFS). The area of coverage includes the Caribbean Sea, the Gulf of Mexico and the Straits of Florida. The system is coupled to NOGAPS/FNMOC and produces nowcast and up to 72 hours forecasts every 24-hr the sea level variation, 3D ocean current, temperature and salinity fields. For the coastal prediction, the sea level variation is the main concern. The surface current, temperature and salinity also are important.

IASNFS consists an 1/24 degree (~5 km), 41-level sigma-z data-assimilating ocean model based on NCOM. For daily nowcast/forecast the model is restarted from previous nowcast. Once model is restarted it continuously assimilates the synthetic temperature/salinity profiles generated by a data analysis model called MODAS to produce nowcast. Real-time data come from satellite altimeter (GFO, Jason-1, ERS-2) sea surface height anomaly and AVHRR sea surface temperature. Three hourly surface heat fluxes, including solar radiation, wind stresses and sea level air pressure from NOGAPS are applied for surface forcing. Forecasts are produced with available NOGAPS forecasts. Once the nowcast/forecast are produced they are distributed through the Internet via the updated web pages.

The open boundary conditions including sea surface elevation, transport, temperature, salinity and currents are provided by the NRL 1/8 degree global model which is operated daily. An one way coupling scheme is used to ingest those boundary conditions into the IAS model. There are 53 rivers with monthly discharges included in the IASNFS.

The IASNFS has been in experimental operation at NRL since December 1, 2002. The preliminary evaluation of the model forecast skill is centered on the coastal sea level prediction. The nowcast/forecast is evaluated against tide gauges in the northern part of Gulf of Mexico and along the Florida coast.