Three-dimensional model simulations for the north coast of British Columbia

A three-dimensional finite element model is used to calculate the barotropic tides and buoyancy-driven flows along the north coast of British Columbia. The model tides are compared to historical constituent harmonics and results from a previous two-dimensional model for the same region. Apart from improvements due to the inclusion of a bottom Ekman layer, the three-dimensional tidal accuracy is essentially the same as that for the two-dimensional model. However, the tidal residual currents are shown to correspond more closely to observations both around Cape St. James and in Dixon Entrance. The diagnostic, buoyancy-driven calculations are forced with the density fields arising from six water property surveys in Dixon Entrance. The model currents are shown to compare favourably with low-pass filtered current meter observations and velocities deduced from drifter tracks. The Rose Spit Eddy is shown to be a consistent feature in all seasons and, as suggested by Bowman et al., its origin appears to arise from a combination of buoyancy-driven and tidally rectified forcing.