A mathematical model for the Baltic Sea has been introduced in an operational system for real-time calculations and forecasts of water temperatures. The model divides the Baltic Sea into 13 sub-basins and treats each sub-basin as a one-dimensional boundary layer with vertical mean velocities based upon in- and outflows from surrounding basins. The operational scheme uses the mode in two modes. The first one, the real-time mode, fits the model to meteorological and oceanographical data collected in the recent past. The second one, the forecast mode, starts from the real-time mode, and calculates forecasts on the basis of the ECMWF weather model and statistics.
The results from about 8 months of pre-operational tests, illustrate that the realtime mode reproduces observed sea surface temperatures quite satisfactorily. However, more efforts must be paid to the obtaining of oceanographic data in realtime. The results from the forecast mode were also satisfactory, but the quality was, of course, dependent on the meteorological forecasts.