Cyclonic cold-core eddy in the eastern North Atlantic. I Physical description

Many rings or eddies have been described in the western North Atlantic, but only a very few in the eastern part. Here we report on a cyclonic cold-core eddy which cut off from a Polar Front meander in the vicinity of 48.5"N, 22" W in May 1985. The eddy extended down to at least 2500 m depth. Its diameter was of the order of 100 km in the upper layer and 200 km at greater depths. Its surface signal was weak in temperature but strong in salinity. Geostrophic circulation around the eddy reached speeds of 30 to 40 cm S-', and net displacement speed was about 3 cm S-' northeastwards. The ambient water mass consisted mainly of North Atlantic Central Water (NACW) from below the surface layer down to 800 m depth. The interior water (core) of the eddy had an interleaving vertical structure consisting of: a mlxture of water types within the upper layer above 200 m depth; NACW between 200 and 400 m depth; predominantly admixtures of Subarctic Intermediate Water (SAIW) between 400 and 500 m depth. Beneath the SAIW and NACW the eddy showed traces of Mediterranean Water in the layer from 600 to 1000 m and deep water with admixtures of Labrador Sea Water at depths between 1400 and 2000 m.