Diurnal Tide Gauge

A diurnal tide gauge is a tide gauge sited and sampled to resolve a diurnal tidal regime, where one high and one low water occur each lunar day rather than the two of a semidiurnal coast. Diurnal tides dominate where the K1 and O1 constituents exceed M2 and S2, as in much of the Gulf of Mexico and parts of Southeast Asia, giving a form number above about 3. The gauge records water level continuously, and harmonic analysis separates the constituents to predict the tide and to define tidal datums. Resolving the single daily cycle correctly matters for datum computation, dredging windows, and storm-tide reference levels.