The flow through the north channel of the Irish Sea

Using Acoustic Doppler Current Profilers (ADCP) and Ocean Surface Current Radar (OSCR HF Radar) a 15-month data set for the current profile and surface currents across the North Channel of the Irish Sea has been collected. During the period July 1993–August 1994 the volume flux through the North Channel between Portpatrick and Bangor was estimated to be (0.077±0.013)×106 m3 s-1 towards the Malin Shelf, concentrated near to the Scottish coast. A simple residual current and wind stress correlation model suggests that large wind stresses were important for residual flow. The current profile in the middle of the channel showed a complex pattern with mean inflow at the surface and mean outflow at the near-bed. Mean along-channel wind stresses for February 1994 and particularly for a large storm during 3–4 February 1994 were atypical of the last decade, with large mean wind stresses directed towards the Malin Shelf. These resulted in: the largest monthly mean flow towards the Malin Shelf, equivalent to 34% of the volume of the Irish Sea passing through the North Channel; the two largest daily mean flows towards the Malin Shelf, equivalent to an along-channel transport of 97 km. Pressure gradients were calculated from elevation measurements and an attempt to calculate the across channel momentum balance was partially successful using Coriolis, Pressure Gradient, Surface Stress, Local Acceleration and Bottom Stress terms.