New computer software that permits more versatility in the harmonic analysis of tidal time series is described and tested. Specific improvements to traditional methods include the analysis of randomly sampled and/or multiyear data; more accurate nodal correction, inference, and astronomical argument adjustments through direct incorporation in the least squares matrix; multiconstituent inferences from a single reference constituent; correlation matrices and error estimates that facilitate decisions on the selection of constituents for the analysis; and a single program that analyzes one- or two-dimensional time series. This new methodology is evaluated through comparisons with results from old techniques and then applied to two problems that could not have been accurately solved with older software. They are (i) the analysis of ocean station temperature time series spanning 25 yr, and (ii) the analysis of satellite altimetry from a ground track whose proximity to land has led to significant data dropout. This new software is free as part of the Institute of Ocean Sciences (IOS) Tidal Package and can be downloaded, along with sample input data and an explanatory readme file.

A finite element, barotropic, tidal model is developed for the north coast of British Columbia.The model is run with eight tidal constituents and the results are compared with the Flather (1987) finite difference model, and with extensive tide gauge and current meter observations. Although the tidal potential, Earth tide, and loading tide are included in the forcing, their inclusion is shown to change the largest M2 amplitudes by only 2.5% and the largest K1 amplitudes by less than 1%. Root mean square differences between observed and calculated sea level amplitudes and phases are within 1.9 cm and 2.9 ø for all but one constituent, but the model currents do not in general, compare as favourably. The barotropic currents observed in Hecate Strait are reproduced well, but elsewhere evidence is shown that model inaccuracies are due to baroclinic effects. Tidal residual currents calculated by the model suggest the existence of eddies off the tip of Cape St. James, Cape Chacon, and around Goose Island and Learmonth Banks. The shallow water constituents in Hecate Strait are shown to have significant contributions from the constructive interference of signals propagating into Dixon Entrance and Queen Charlotte Sound. Using the model, the longest resonant period of the system is estimated to be 7.6 hours with an energy dissipation parameter, Q, of 9.5. This paper is not subject to U.S. copyright. Published in 1993 by the American Geophysical Union. Paper number 92JC02470. and 2). These islands are separated from the mainland by three bodies of water: Dixon Entrance, Hecate Strait, and Queen Charlotte Sound. Whereas Dixon Entrance is approximately 150 km in length, 55-65 km in width and has depths as large as 400 m, the other two inland waters are not so regular. Hecate Strait is very shallow (less than 30 m) on its western half and has only a narrow north-south trench with depths greater than 100 m on its eastern side. Queen Charlotte Sound is characterized by three relatively deep troughs that separate Cape St. James, Middle Bank, Goose Island Bank, and the Scott Islands. Other notable features of the region are the highly irregular mainland coastline comprising numerous narrow passes and fiords, the narrow continental shelf off the west coast of the Queen Charlotte Islands, and the presence of seamounts (e.g., Union and Bowie) beyond the continental slope. Detailed descriptions of the physical oceanography of the region have been given by Crean [1967], Dodimead [1980], Thomson [1981], Freeland et al. [1984], Crawford et al. [1988], and Crawford and Thomson [1991]. There have been several previous tidal models for this region. Bell and Boston [1962, 1963] developed a non-rotating hydraulic model for Hecate Strait, Dixon Entrance, and Queen Charlotte Sound that gave a reasonably successful representation of the diurnal and semi-diurnal tidal heights. However, their M2 tidal currents had large phase shifts relative to observations in Dixon Entrance and inaccurate residual currents near the forcing boundaries. The first nu...

Altimetry from the TOPEX/POSEIDON satellite is anMyzed 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 M2, S2, and K1 tide removal from TOPEX/POSEIDON Mtimetry can introduce systematic biases to the calculation of seasonally averaged fields. Average summer and winter sea surface heights are calculated from the detided Mtimetry, 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. the altimeter and the virtually global coverage of the satellite tracks means that T/P will be able to provide valuable information for monitoring the ocean circulation and the effects of climate change. Furthermore, data from this mission together with analogous measurements from Geosat, ERS 1, ERS 2, Envisat, and the Geosat follow-on (GFO) and T/P follow-on (JASON 1) missions that are planned for launch in 1998 and 1999, respectively, mean that the prospects 1Department of Fisheries and Oceans, Institute of Ocean Sciences, Sidney, British Columbia, Canada. 9'Canadian Hydrographic S,-. vice, Institute of Ocean Sciences, Sidney, British Columbia, Canada. aHermes Computing Services, Victoria, British Columbia, Canada. Paper number 98JC02671. 0148-0227 / 9 a / 98 J C-o2671 $09. oo for sea level time series spanning at least 2 decades are very good. Fu et al. [1994] give an excellent overview of the mission, while Fu et al. [1996] provide a brief summary of early T/P results. An extensive list of T/P-related publications is made available at http' //TOPEX-www.jpl.nasa.gov/science/post-nov.html. T/P, with a repeat orbit of 9.9156 days, has nine tracks crossing approximately perpendicular to, and three tracks running relatively near and parallel to, the British Columbia coast. (See Figure 1.) (Two additional tracks crossing the Strait of Georgia might also prove to be valuable if signal interference due to the proximity of land can be reduced.) Although many corrections are required to convert the altimeter signal to a sea level measurement, most of these are quite standard and highly accurate. However, one correction that is often inaccurate is the removal of local tidal elevations. Although T/P altimetry, as received from the Jet Propulsion Laboratory (JPL), provides the necessary information to have the tide removed by either of two world tidal models, CSR3.0 [Eanes and Bettadpur, 1995] or FES95.2.1 (an update of Le Provost et al. [1994]), these m...

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