THE RESPONSE OF THE IRISH SEA TO BOUNDARY AND WIND FORCING - RESULTS FROM A 3-DIMENSIONAL HYDRODYNAMIC MODEL

A three dimensional, nonlinear hydrodynamic model of the Irish Sea is used to examine the response of the region to forcing along its open boundary and wind stress over the area. Frictional dissipation at the bed is parameterized with a quadratic law of bottom friction, which can take account of enhanced frictional effects due to wind wave/current interaction. A standard finite difference grid is used in the horizontal, with an expansion of functions through the vertical, giving a continuous current profile from sea surface to seabed. The model has a grid resolution of the order of 3 km and hence can resolve some features of the nearshore region. The model is forced with M(2) tidal input along its open boundary, and time invariant wind fields, corresponding initially to spatially uniform northerly and westerly wind stresses of 1 N/m(2) and subsequently to a west-east gradient wind changing from -1 N/m(2) to +1 N/m(2) going from west to east, and a north-south gradient wind changing from 1 N/m(2) to -1 N/m(2) going from north to south. The response to open boundary forcing through both elevations and currents is also examined, and the influence of the effects of enhanced bottom friction due to wind waves is also briefly considered.