Development and validation of a three-dimensional curvilinear model for the study of fluxes through the North Channel of the Irish Sea

A three-dimensional non-orthogonal curvilinear model has been developed for the Celtic Sea, Irish Sea and North Channel. With a maximum resolution of approximately 1 km in the North Channel, the model resolves the complex topography and horizontal flow variability in this region, whilst the large geographical domain enables the inclusion of far field forcing. Predicted co-tidal charts of the region are in good agreement with published charts based on observed tidal elevations and from previous modelling studies. Comparisons of observed and predicted M2 and S2 tidal elevations and currents suggested that in general, this model is considerably more accurate than a previous large area, coarse resolution model of the region, and comparable with previous high-resolution limited area models. The predicted tidal residual flow through the North Channel of 0.023 Sv is in good agreement with previous modelling studies. These residual currents showed considerable spatial variability in the North Channel, clearly demonstrating the importance of a high resolution grid in this region. Of particular interest are the predictions of a strong cyclonic gyre at the mouth of Belfast Lough, and a strong southwards coastal current along the Mull of Galloway. The latter may in part explain the observations of fresher water in this region.