THE INTERNAL TIDE OFF THE WEST-COAST OF VANCOUVER ISLAND

Using data from the Coastal Ocean Dynamics Experiment (CODE) and the I sland Coastal Current Experiment, the internal tide off the west coast of the Vancouver Island was studied. Although the semidiurnal barotro pic velocity field in the area was weak, the baroclinic field was foun d to be relatively strong with speeds up to five times greater. The in termittent nature of the baroclinic field was resolved by estimating t he M2 tidal harmonic coefficients every 24 hours in 15-day overlaping intervals. These time-evolving coefficients were then analyzed using s pectral analysis methods. For most of the area under investigation, th e internal tide was generated mainly at the shelf break and was found to propagate cross-shore. Off Estevan point, where the bottom contour is regular, the beam structure was identified and traced to distances 40 km from the generation region on the slope. The downward-propagatin g beam was found to follow the seasonal variation of the characteristi c propagation paths. An empirical orthogonal function analysis reveale d a highly coherent baroclinic field (78% of the M2 variance). The pre dictions of an internal tide model were found to be in good agreement with the experimental results on the slope. The interaction of a cyclo nic eddy, present in the area during August 1980, with the internal ti de was also addressed.