The TOPAZ ocean modelling and forecasting system uses an advanced data assimilation method (the Ensemble Kalman filter) with the HYCOM model coupled to a sea ice model and an ocean biogeochemical model (HYCOM-NORWECOM). The model system is developed for the North Atlantic and the Arctic Ocean and set up for both real time forecast and reanalysis activities, assimilating several types of satellite and in-situ data and providing lateral boundary conditions to nested high-resolution models of the Barents Sea, the Fram Strait, the Norwegian Sea and the Gulf of Mexico. Similar systems are set up for Indian and Southern Ocean and the Pacific Ocean.

The observations assimilated into the TOPAZ system are satellite observed Sea Level Anomaly (SLA), Sea Surface Temperature (SST), Sea-ice concentrations from AMSR-E, sea-ice drift products from CERSAT and Coriolis and Argo in situ temperature and salinity profiles.

The TOPAZ4 system has been run in reanalysis mode in a pilot phase (2003-2008) the data is provided on the OPeNDAP server, as presented in "The TOPAZ4 pilot reanalysis (2003-2008)".

The TOPAZ4 system is exploited in met.no's operational suite providing short term (10 days ahead) ocean and sea ice forecasts daily, open for public access and end users. See the MyOcean web-page at met.no.