The shelf-edge current north-west of ireland

Abstract

Measurements of the slope current at two locations north-west of Ireland have been made between April and December 1994, 40 m above the seabed in a water depth of 660 m. A persistent poleward along-slope current was observed at both locations, with measured means of 10 and 21 cm s(-1) respectively. A CTD transect across the slope near one mooring indicated the presence of a light, warm, saline core of water at the shelf edge. Peak currents were O(50) cm s(-1) with strongest mean flow at the location with steeper slope. Variability at sub-tidal periods, principally 2-5 and 11-12 days, was apparent. The shorter-period variability was well correlated with coastal sea-level variations measured at a land point near to one of the moorings. The variability in the slope current at this period appeared to be a result of the warm current core movement up/down slope, probably as a result of interaction with higher-mode shelf waves. Some suggestion of a bottom-trapped diurnal wave was also found at one location.