Tidal Harmonic Analysis

Big Ben and The Houses of Parliament, River Thames, London, UK Tower Bridge, River Thames, London, UK

In most places in the world, the ocean tide is primarily caused by the moon and the sun. This part of the tide is known as the "Astronomical Tide".


The remaining, smaller and more unpredictable portion of the tide, is caused by meteorological and seismic effects; i.e. weather and earthquakes. It is sometimes known as the Surge Tide and is the difference between the observed and the predicted "Astronomical Tide" More on Surge Prediction.


Tidal Harmonic Analysis calculates the "Astronomical Tide". When a harmonic analysis is carried out, past tidal records are compared with the known tidal force of the sun and moon as described by an almanac, to produce the harmonic constants. At a given tidal location the harmonic constants represent the ocean's response to the tidal forces of the Moon and the Sun at different frequencies. To make a prediction, these harmonic constants are used, together with the internal almanac to accurately predict the 'Astronomical Tide'. Thus, tidal prediction is the inverse process of tidal harmonic analysis.


Our software application GeoTide, designed for the professional hydrographer, handles every step in tidal analysis and prediction, in an intuitive and user-friendly way. As a by-product GeoTide can also calculate the tidal levels. More on GeoTide.



Analyzer Screen