Extraction of M2 internal tide near Hawaii using 10 years TOPEX/Poseidon altimeter data

Harmonic analysis of 10 years of TOPEX/Poseidon (TP) along-track altimetry is performed to derive the semidiurnal and diurnal tides (M₂, S₂, N₂, K₂, K₁, O₁, P₁ and Q₁) near Hawaii. And there is a good agreement between the tide harmonic constants derived from the T/P altimeter data and that derived from the tide model of Oregon State University. Based on these reliable harmonics, the method of polynomial fitting, however two strategies, is used to extract the internal tide sea surface signals. One is to fit the values A (amplitude) and G (phase-lag) respectively; the other is to fit the AcosG and ASinG respectively. The comparison between these two strategies shows the latter one is better and the results of eleven order polynomial fitting are the best, which can completely separate the barotropic and baroclinic components. With this method, a good internal tide sea surface distribution also can be given near Hawaii.