The influence of shelf edge flows and wind upon the circulation on the Malin Shelf and in the Irish Sea

A three-dimensional hydrodynamic model covering the area off the west coast of Scotland and part of the ocean beyond, and extending south through the North Channel and into the Irish Sea is used to examine wind-driven and oceanically forced currents in the region. The effect of friction on the shelf due to tidal currents upon the extent to which the shelf edge flow can “leak” onto the shelf is also considered. Calculations in which an Atlantic inflow is introduced in initially deep water, and subsequently shallow water off the west coast of Ireland, demonstrate the processes by which this inflow can cross the shelf edge, and Atlantic water can reach the west coast of Scotland and enter the Irish Sea. The interaction of this flow with wind-induced flows due to uniform southerly and westerly winds is also considered. Also, the role of a northward flow into the Irish Sea through St Georgeʹs Channel in modifying the wind and Atlantic forced currents on the shelf is examined. The spatial variability and the level of interaction between these flows help to understand the spatial and temporal variability found in the measurements in the region.