Transects by submarine of the East Greenland Polar Front

Abstract

Seven transects of the East Greenland portion of the Polar Front were made by HM nuclear submarine Sovereign in October 1976. The transects, between 71 and 81°N, comprise continuous horizontal sound velocity profiles at depths of between 67 and 125 m, accompanied by inverted sonar profiles of the ice canopy overhead. Features of the sound velocity profiles include steep thermal fronts; high-frequency structure, possibly due to internal waves and found mainly in the Front; and warm water patches within the zone of Polar Water, probably due to eddies. Once the submarine passed through the Front twice by diving, which enables an estimate of its slope to be made. The nature of the features that suggest internal waves and eddies is considered, and an analysis is made of the extent to which a warm surface eddy can cause the ice cover to melt if assisted by wave action. A laboratory experiment is also described in which the East Greenland Current was modelled by releasing a cylinder of salt water placed in the centre of a rotating circular tank of freshwater, with a radial barrier simulating Greenland. A current was obtained along the eastern side of the barrier, reproducing many of the qualitive features of the East Greenland Current.