Harmonic Analysis
D2. Hydrography, tides, waves, bathymetry and marine geologyDefinition
Decomposition of a tidal record into sinusoidal constituents.
Tidal harmonic analysis decomposes an observed water-level record into a sum of sinusoidal constituents at known astronomical frequencies, solving for each constituent’s amplitude and phase (its harmonic constants) by least squares. A record of a month resolves the major constituents; a year or more separates closely spaced ones and the annual and nodal terms. The fitted constants then drive tide prediction anywhere the record was taken.