An investigation of meteorological effects on currents in the shelf and continental slope seas northwest of the U.K. I: analyses for individual moorings

This report describes analyses of data from the continental shelf and slope northwest of the UK in the period 19 August 1982 to 23 March 1983. Current meter data are included, notably from the Continental Slope Experiment (CONSLEX), and also sea-levels, sea-floor pressures and temperatures, atmospheric pressure and winds. The series were low-pass filtered to exclude inertial oscillations (period ~ 14 hr) but retain periods exceeding 20 hr. Mean currents, and measures of variability and its character, are discussed for the filtered series. Mean currents are generally northwards/northeastwards along the continental shelf and slope, but are stronger over the steep slope and increase northeastwards, finally exceeding 0.4m/s near the surface at 0°E. Current fluctuations also increase northeastwards, to over 0.2m/s r.m.s. in the Faeroe-Shetland Channel; over the steep slope and adjacent shelf positions, the fluctuations are aligned predominantly along the slope. Mean and fluctauting currents are principally barotropic (albeit decreasing downwards) except for reversals in the cold bottom waters of the Faeroe-Shetland and their flow over the Wyville-Thomson Ridge. Near-diurnal oscillations are occasionally prominent, especially on the West Shetland Shelf; exceptionally they dominate the tides in 500m depth at 0°E. Some events (slope current reversals, particularly strong current fluctuations, exceptionally deep atmospheric depressions) were chosen for individual analysis