COMPARISON BETWEEN THE HARMONIC AND RESPONSE METHODS OF TIDAL ANALYSIS USING TOPEX POSEIDON ALTIMETRY/

Three years of TOPEX/POSEIDON altimeter data have been processed at De lft Institute for Earth-Oriented Space Research (DEOS) to solve the ma jor diurnal and semi-diurnal constituents of the global ocean tide usi ng the two classical methods of tidal analysis, i.e. the harmonic and response analyses. Some experiments with the parameters in the respons e formalism show that the tidal admittance in both the diurnal and sem i-diurnal band can be adequately described with a lag interval of 2 da ys and a number of lags of three. Results of both methods are evaluate d from the differences with the most recent Grenoble hydrodynamic mode l (FES95.2) and from the fit with the harmonic constants of a globally distributed set of tide gauges. It was found that the solutions of th e two methods differ at the millimeter level and are thus fully equiva lent, which is confirmed by the tide gauges and the differences with F ES95.2. From the comparisons with the Grenoble model it was found that the M-2 and S-2 solutions of that model likely contain bathymetric er rors which are of the order of 1-2 cm for M-2 and 0.5 cm for S-2.