On the hydrographic fluctuations in the Labrador Sea during the years 1959-1969

Abstract

During the years 1959 - 1969 Norwegian fishery research vessels collected oceanographic data off West Greenland, the observational work mainly being done in April. The data reveal gradually falling temperatures in the upper layers because of increasing supply of Arctic water to the West Greenland Current during the 1960s. The reason for this seems to be the atmospheric pressure and wind conditions which also were in favour of an offshore drift of the surface waters along the West Greenland coast. Between the surface waters of Arctic characteristics and the Irminger water below vertical convection was to a great extent prevented by a transition layer of high stability. The radiant heat loss during the winter season was, therefore, limited to the upper layers, adding to the decrease in temperature created by the growing supply of Arctic water. In waters of salinity below 34%, in the section across the Fylla Bank the temperature fell by 1.6°C during the period. The trend in the Irminger water was different, and the temperature in this water mass rose until 1966. The cooling in the upper layers can be traced down to approximately 400 m depth, but it was most pronounced at 100 to 150 m depth off the edge of the shelf where the temperature fell by about 2°C. At depths below 400 in the warming effect of the Irminger water can be traced down to 1 000 to 1 200 m depth.