Tidal correction of TOPEX/POSEIDON altimetry for seasonal sea surface elevation and current determination off the Pacific coast of Canada

Altimetry from the TOPEX/POSEIDON satellite is analyzed for the waters off British Columbia, Canada. Tides are removed using harmonic constants from two coastal and two global models, and the accuracy of this detiding is assessed by using these same models and one digital filter to remove the tide from the time series of three representative coastal tide gauges. It is demonstrated that inaccurate M-2, S-2, and K-1 tide removal from TOPEX/POSEIDON altimetry can introduce systematic biases to the calculation of seasonally averaged fields. Average summer and winter sea surface heights are calculated from the detided altimetry, and estimates of their accuracy nearshore are computed using concurrent time series from 11 tide gauges. Finally, these seasonal elevations are blended with those from the 11 tide gauges, and the associated surface currents are calculated using a diagnostic finite element model. These currents are compared with those calculated from historical conductivity and temperature versus depth measurements and those measured by historical near-surface current meters.