A number of studies have aimed to find those factors affecting the drag coefficient at the ocean surface. The direction of swell relative to the local wind has been proposed as a contributing factor. Different approaches have been used, but the results have been inconclusive. Here observed and modelled 2D wave spectra are compared. The data is obtained by the microwave MIROS-radar and the WAM-model (cycle-4) at different locations in the North Sea and Norwegian Sea. Based on the fact that the WAM source functions are not accounting for swell effects, a difference between the observed and...