Improvement of hydrodynamic forecasting of Danish waters: Impact of low-frequency North Atlantic barotropic variations

Abstract

The Danish Maritime Safety Administration (DaMSA) provides forecast of elevations, currents, and other parameters to the maritime society. Accurate and reliable predictions are important to help navigate Danish waters in a safe manner, and the forecasts are routinely used by the Vessel Traffic Services in the Great Belt and the Sound. The DaMSA model setup includes three nested models, with coarse resolution in the North Atlantic and increasing to 600 m in the Belt Sea and South West Baltic. Observations of some special events in late 2009 drew attention to a possible relation between Atlantic-scale surge events and small-scale currents in the Danish Straits. During the special event with large-scale surge, the observed southward moving current in the Danish Straits was 0.5-2.0 m/s for several days, while the operational model showed a much smaller response. As a consequence, the entire DaMSA model complex was revised during 2010. Multi-annual reruns have showed that with the updated model, the explained variance of the current increases from 67% to 88%. © 2011 The Author(s).