Comparison of hydrodynamic models of the Baltic Sea (MUSTOK)

The study aims to compare the results of hydrodynamic simulations of a Baltic Sea model developed at FTZ on the base of the Mike-modelling system of the Danish Hydraulic Institute on the one hand with the operational model system of the North and Baltic Sea developed by the German Bundesamt für Seeschifffahrt und Hydrografie (BSH) on the other hand.

Area of the Baltic Sea Model, Operational model of the North and Baltic Seas

The Baltic Sea Basin on the first of April 2004, SeaWiFS (NASA, GeoEye)

Duration: 2005-2008

For a better estimation of the reliability of a quantitative model it is either important to verify its results against measurements or to compare the results with those of a different modelling systems. These comparisons are of particular interest if predictions are provided or if synthetic scenarios are simulated, when a direct verification of results against field data is not possible. In the project MUSTOK two modelling systems were used for the simulation of storm events in the German Baltic Sea allowing for the comparison of the two models.

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Left: Baltic Sea Model of FTZ (MIKE3), Right: Operational Model of the North and Baltic Seas, BSH (BSHcmodv4).  © G. Bruss


Two readily set-up models of the North- and Baltic Sea where applied using the codes of BSH and DHI. A detailed comparison of the model results was done for the hind cast of two storm events. The differences between the models were found to be small, in the order of few centimetres and both models reproduced the surges within errors of around 10cm with respect to the observations. Considering the high sensitivity of storm simulations to the wind drag coefficient, different settings were tested in both models. Both models reacted similarly.

Slight differences in the response to wind drag changes are mainly assigned to differences in the model resolution. Meteorological data from the operational cosmo-eu model of the German weather service was used in both models and for both storms. Bork & Müller-Navarra (2009) describe the influence of using wind data from different meteorological models to simulated the same storm. The differences in the water levels were substantial and considerably larger than between the two hydrodynamic models underlining the importance of accurate forcing data.

Research divison:

Coordination:

  • Prof. Dr. R. Mayerle

Staff:

  • G. Bruss

Partners:

  • BSH