Investigating the effect of a wave-dependent momentum flux in a process oriented ocean model

New expressions of the drag coefficient were developed using measurements from the Ostergarnsholm site in the Baltic Sea. The drag coefficient was significantly lower in the presence of waves travelling faster than the wind (swell). The expressions were implemented in an oceanographic process-oriented model in a 45-year simulation. Since no wave information was included we did an analysis of the potential impact of swell on an ocean model. Current velocity and surface stress were significantly altered during periods with low wind speed but the temperature and the mixing depth in the ocean were not significantly changed. The implementation of the swell effect in a process oriented ocean model is thus of limited importance. There is, however, an indication that for studies of current velocity it is crucial to have a correct description of the drag coefficient.