Empirical cotidal charts of the Bohai, Yellow, and East China Seas from 10 years of TOPEX/Poseidon altimetry

[1] Harmonic analysis of 10 years of TOPEX/Poseidon (TP) along-track altimetry is performed to derive the semidiurnal, diurnal, long-period, and quarter-diurnal tides in the Bohai, Yellow, and East China Seas. The TP solutions are evaluated through intercomparison for crossover points and comparison with the ground truth, showing that the accuracy of TP solutions in the study area has achieved levels of 2 - 4 cm in amplitudes and 5degrees in phase lags for principal constituents (M-2, S-2, K-1, O-1, and S-a). The TP-derived S-a amplitudes have a systematic bias of about - 10% as compared with the ground truth, indicating the possible importance of loading effect of this constituent in the study area, which is generally not considered in geodetic surveys. The tidal harmonics from TP altimetry and at coastal and island stations are used to give a new set of empirical cotidal charts for principal constituents (M-2, S-2, K-1, O-1, and S-a). The accuracy of these new charts is believed to be significantly higher than the previous charts for the offshore area.