Sea surface temperature patterns and air‐sea fluxes in the German Bight during MARSEN 1979, Phase 1

Abstract

An analysis was made of remotely sensed sea surface temperatures (SST) obtained from aircraft and satellites and of data from hydrological surveys conducted in the German Bight during the Marine Remote Sensing Experiment (MARSEN) phase 1, in the North Sea August 15 to September 15, 1979. The signature of a thermal double frontal structure associated with a coastal front resulting from freshwater runoff and extending along the 30‐m bottom contour at the northeastern edge of the submarine glacial valley of the Elbe river was the most prominent feature in the SST field. Air‐sea fluxes of heat and momentum were computed for the same period from field observations by using recently developed parameterization schemes. It was possible to group the SST patterns according to the intensity of the wind stress and of the net heat gain or loss by the sea. It was found that the thermal signal of the front is more evident at the surface when the wind stress is greater than about 0.5 N m−2. In the summer of 1979 these occasions were also associated with weak heating or with a net cooling of the sea. During periods of weaker wind stress and strong solar heating, a shallow thermocline develops which tends to isolate the frontal cold water from the interface and the SST pattern becomes less organized. Frontal eddies related to the baroclinicity and to the current shear at the frontal zone were visible in the surface distributions of density and on the satellite infrared imagery.