3 
1 
Introduction 
Operational numerical models have been used at the Bundesamt für Seeschifffahrt und 
Hydrographie (BSH) 1 for many years now to support various maritime services (Dick, 
1997, Huber, 1993). "Operational" means that the models are used for daily routine 
simulations of the North Sea and Baltic Sea dynamics, i.e. currents, temperature, salinity, 
dispersion of substances etc. Although the model system had been designed primarily as 
a tool for several BSH services, the simulation data have also been used in oceanogra 
phic and maritime research projects. 
One of the most important applications of the numerical models is the support of the 
BSH’s water level prediction and storm surge warning service, which is supplied with 
computed water level forecasts. Other important applications are drift prognoses for oil, 
chemicals and dangerous drifting objects as well as the support of search and rescue 
operations. Operational model data have been used successfully in marine pollution 
combating operations (Theobald et al., 1992, Dahlmann and Müller-Navarra, 1997, 
Huber and Dick, 1998). Occasionally, drift calculations for plankton and larvae have been 
carried out to support fisheries. 
The BSH receives many inquiries concerning current data. Its model data have been 
used, e.g., in tidal stream atlases (e.g. Dick et al., 1992), for ship routing and in the 
preparation of sailing competitions. Meanwhile, modelled current nowcasts and forecasts 
(hours to days ahead) for maritime shipping are also available on the Internet 
(www.bsh.de). It will be possible in future to integrate these and other model predictions 
into electronic chart displays (ECDIS). Future applications will include model predictions 
to support the BSH's ice and sea surface temperature service, tidal reduction of sound 
ings in hydrographic surveying, and charting on the basis of computed water level data. 
The model system comprises several computer programmes which automatically 
produce data without any manual intervention being required (Fig. 1). On the basis of 
meteorological and wave forecasts supplied by the German Weather Service (Deutscher 
Wetterdienst, DWD) as well as tide predictions, the model computes a daily "weather 
forecast” for the sea. The model system is an in-house development of BSH. Its main 
constituents are a hydrodynamical model to compute currents, water levels and 
temperatures, salinities and ice cover in the North and Baltic Seas (BSH circulation 
model, BSHcmod) and programmes to compute the drift and dispersion of substances 
(Lagrangian and Eulerian dispersion models, BSHdmod.L and BSHdmod.E). Other 
components of the model system are a surge model (BSHsmod), which has been 
developed to support the water level prediction service with medium range (84 hours) 
surge predictions (Janssen, 1996, Janssen and Dick, in prep.), and regional models for 
selected German estuaries and coastal areas (e.g. Dick and Schönfeld, 1996). 
1 Federal Maritime and Hydrographie Agency, formerly: Deutsches Hydrographisches Institut (DHI)