Tide Prediction

Tide prediction computes future water levels by summing the tidal harmonic constituents (M2, S2, K1, O1 and dozens more) whose amplitudes and phases were fitted to a long observed record by harmonic analysis. Each constituent is a sinusoid at an astronomical frequency derived from the relative motions of the Moon and Sun, modulated over the 18.6-year nodal cycle. Published tide tables and chart-datum heights come from this method.