Harmonic Constituent
D2. Hydrography, tides, waves, bathymetry and marine geologyDefinition
Sinusoidal component of the tide such as M2 or S2.
A tidal harmonic constituent is one sinusoidal component of the tide at a fixed astronomical frequency, named by a symbol and subscript: M2 (principal lunar semidiurnal, 12.42 h), S2 (principal solar semidiurnal, 12.00 h), K1 and O1 (the main diurnals). Each has a local amplitude and phase. Their relative sizes set the tidal character (the form number), and their sum, evaluated forward in time, is the predicted tide.