content in the North Sea and the Baltic Sea

A 3-d baroclinic coupled ice–ocean model, applied to the connected marginal seas, North Sea and Baltic Sea, was used to investigate the seasonal cycle of both heat content of the water column and atmosphere–ocean heat exchange throughout the seasonal cycle. Case studies were carried out to investigate, quantify and inter-compare the intra-annual sensitivity of the thermal state of both marginal seas in response to changes in wind forcing, air temperature and fresh water runoV. The prescribed changes in model forcing were well within the range of the observed variability. A simulation for a representative reference case (1984–84) served to quan-tify predicted anomalies. Reducing the fresh water runoV for both seas by 30 % resulted in a surprisingly small response in the heat content which was one order of magnitude smaller as compared to the applied change in wind forcing. A reduction of the air temperature by 2°C caused a decrease of the heat content throughout the seasonal cycle in the order of 30%. In contrast to a change in air temperature a reduction of 30 % in wind stress yielded distinct seasonal diVerences in the oceanic response. The most significant wind induced changes occurred during autumn and winter in the Baltic Sea and in the North Sea. A reduced wind forcing led to a larger oceanic hea