Tidal variations can be represented by summing a series of harmonic terms. Listed below are the four largest harmonic constants (or tidal constituents) M2, S2, O1 & K1 together with the mean value Z0.
Each harmonic term has the form:
Hn cos (σnt − gn)
where Hn is an amplitude in metres, gn is a phase lag on the Equilibrium Tide at Greenwich in degrees, σn is an angular speed and t is time.
To produce a full accurate tidal prediction it is often necessary to use more than a hundred of these harmonic terms. These results were generated by tidal analysis using tide gauge data spanning the dates listed.