On the circulation of the northeastern North Atlantic

Abstract

Along a section from Cape Farvel at the southern tip of Greenland to the Porcupine Bank off the Irish coast (WOCE section A1E/AR7E), obtained in September 1991, geostrophic velocities were calculated from CTD measurements and referenced to velocities recorded by an Acoustic Doppler Current Profiler (ADCP) in the upper 500 m. The mean accuracy of the absolute geostrophic velocities is estimated at±3.6 cm/s, which is comparable to that resulting from the assumption of a layer of no motion. The derived flow field is essentially columnar without a pronounced layer of no motion. Maximum velocities of 20–30 cm/s occur in the upper 1000 m of the East Greenland Current and the Porcupine slope current and at 2000 m depth in the Denmark Strait overflow. The meandering of the Irminger Current crossing the Reykjanes Ridge and an enhanced mesoscale variability along the Rockall Plateau and in the Rockall Trough are indicated. Compared to Schmitz and McCartney (1993) the estimated volume transports suggest an intensified meridional circulation with an increased supply from the subtropics to the Subpolar Mode Water (SPMW) and an increased entrainment of SPMW into the deeper layers. In the bottom layer with densities σ 0 ⩾ 27.80 kg/m 3 a reduced circulation of Iceland-Scotland Overflow Water (ISOW) in the Irminger Basin and a recirculation of ISOW in the Iceland and West European basins are found. About 12 Sv of bottom water are transported southwards and join the Deep Western Boundary Current.