The Wind Influence on the Jutland Coastal Current Interpreted on the Basis of som Observations

Abstract

The Jutland Coastal Current (JCC) is a freshwater-influenced coastal current localised in the south-eastern part of the North Sea. Its main sources are the Elbe, the Weser, and the Ems, which run into the German Bight, as well as smaller rivers along the Danish west coast. Tides, buoyancy and wind mainly determine the flow field in the Jutland Coastal Current. The Ekman transport in the North Sea far away from land feeds the coastal current along the Jutland coastline within approximately one Rossby radius of the coastline. In this study the influence of the wind on the Jutland Coastal Current (JCC) is investigated on the basis of measurements of wind, salinity, nitrate and current. The wind determines the spatial extent of the current and only during south-southwesterly winds does the JCC flow into the Skagerrak. The major river discharge into the German Bight in 1995 was followed by a decrease in the salinity outside Hirtshals after only 21-45 days in connection with changing southerly and westerly winds. On the 50-hour time-scale the wind determines the gross and residual transport in the JCC as expected from the Ekman transport, together with minor contributions from the buoyancy and tide. The spatial nitrate distributions clearly indicate an inter-annual variation in the nitrate concentrations and thus influence the transport of nitrate.