Application of a large area curvilinear model to the study of the wind-forced dynamics of flows through the North Channel of the Irish Sea

A three-dimensional non-orthogonal curvilinear model of the Celtic Sea, Irish Sea and North Channel has been applied to the study of the wind-induced dynamics of the North Channel. With a resolution of approximately I km in the North Channel, the model resolves the complex topography and horizontal flow variability in the channel. The large geographical domain enables the inclusion of far field forcing and is thus a significant improvement on high resolution localized grids of the region. Initial simulations with uniform winds of varying orientation with respect to the channel demonstrate the importance of adequate representation of far field effects, with wind-induced surface elevation gradients playing a significant role in both the magnitude and direction of predicted depth-mean currents. Model predictions for two periods in 1994 (24 January-8 February and 12-22 September) compare well with observed currents when spatially varying wind forcing is applied. The poor predictions resulting from the use of non-spatially varying winds and a smaller model domain further emphasize the importance of appropriate representation of far field effects. The significance of a storm event on 3-4 February is discussed in the context of a 4-month period of model simulations and the consequence of these findings for our understanding of the mechanisms governing the flushing of the Irish Sea is considered. Crown Copyright (C) 2001 Published by Elsevier Science Ltd. All rights reserved.