Tidal Harmonic Analysis

The ocean tide is primarily caused by the moon and the sun, is predictable and is highly relevant to shipping.


GeoTide predicts the tide using a two step process. First, the harmonic constants are produced from tide gauge records. Then, the harmonic constants are used to predict the tide for publication in tide tables. The harmonic constants can also be used to calculate the tidal levels, such as Lowest Astronomical Tide (LAT), Highest Astronomical Tide (HAT) etc. Both tidal predictions and tidal levels are important in shipping, navigation, cartography, hydrography and marine survey.


When tidal harmonic analysis is carried out, past tidal records from a tide gauge are compared to the known harmonic tidal forces of the sun and moon; the comparison creating a set of harmonic constants. The harmonic constants represent the ocean's response to the tidal forces of the Sun and Moon at specific frequencies. To make a prediction, the inverse process is carried out, the harmonic constants are combined with the known harmonic tidal forces to predict the tide.


Our software application GeoTide handles every step in this process, in an intuitive and user-friendly way. Literally in just a few minutes, within a few mouse clicks, the input data is converted into harmonic constants and then into tide tables for any date. GeoTide also calculates the tidal levels, these significant contours show the maximum and minimum coverage of the tide, and are used mainly in navigation.


More on Tidal Levels



Analyzer Screen