NEAR-SURFACE CIRCULATION OF THE NORDIC SEAS AS MEASURED BY LAGRANGIANDRIFTERS

In the period June 1991 to August 1993, 107 Argos tracked, drifters dr ogued to 15 m depth, were released in the Nordic seas (or Greenland, I celand, and Norwegian Seas). The drifter movements revealed the strong and spatially confined current systems along the surface salinity fro nts of the Iceland-Faroe Frontal zone and of the Norwegian coast and a long the continental margins and their extensions to the Barents Sea a nd Spitsbergen. The Norwegian Atlantic Current is composed of three di stinct streams (two continental margin and one coastal branches) which join into one single swift mean current west of the Lofoten and Veste ralen Islands, where the strongest measured currents are in excess of 110 cm s(-1). In addition to the general cyclonic gyre circulation in the Nordic seas, the drifters indicate smaller cyclonic circulation pa tterns in all the major subbasins, i.e., the Iceland plateau, the Norw egian, the Lofoten, and the Greenland basins. No surface signature of the East Icelandic Current is disclosed by the drifters, Interpolated and low-pass-filtered position data were used to construct maps of 15- m-depth ensemble mean velocity, velocity variability, and residence ti me. Vigorous eddy fields are dominant in the strong currents and in th e Lofoten basin, Eulerian correlations indicate that they tend to prop agate to the west. In contrast, the Iceland plateau appears quiescent, both in the mean and eddy velocities. Single-particle diffusivities a re computed and are found to be in the range 1-7 x 10(7) cm(2) s(-1). The corresponding Lagrangian timescale and space scale are 1-3 days an d 10-40 km, respectively. These Lagrangian drifter measurements compos e the first basin-scale, accurate near-surface velocity data set of th e Nordic seas.