A Tidal Model of the Northeast Pacific

The development of a tidal model for the west coast of Canada is described. The model is intermediate in resolution between coarse-gridded global models and fine-gridded local models; it provides a good representation of the main shelf regions and also includes a substantial area of the neighbouring ocean. The physical processes relevant to tides in both deep and shallow water are included. Calculations have been carried out for the M(2) and K(1) constituents and the model results were compared with extensive tide-gauge observations and empirically based charts. For M(2), the agreement between model results and observations is generally excellent, but for K(1), which contains more small-scale variability, the model results are not quite so good. The variability in K(1) is associated with tidally generated continental shelf waves. Examination of the computed currents and energy fluxes suggests that shelf-wave components are present in the model solution but, for the Vancouver Island shelf, their propagation is not reproduced accurately. This may be due to deficiencies in the model and/or to the influences of stratification and mean currents, which are neglected here. The model predicts that shelf-wave components should also occur in diurnal tides on the Alaskan shelf. The significance of the tide-generating potential and advection are also examined and further work proposed.