Tidal monitoring with Sentinel-2

Tidal phenomenon along the shores was well known since the prehistoric era, but a long trip of investigations through the centuries was necessary from the Greco-Roman Antiquity to the modern era to unravel in a quasi-definitive manner many secrets of the ebb and flow.

Tides were firstly studied by Greek philosophers who tried to find an explanation to the difference of the sea level between day and night often providing astrological accounts to the effect.

Imaginary explanations for the tides involving the “pulse” or the “breathing” of huge sea god may also be found in the some old Indian and oriental texts.

The Stoic, Posidonius (I sec. BC) gave the first reasonable description of the phenomenon from personal observations detailing different cycles of tides strictly related to the motion of the moon.

Almost 16 centuries later, Galileo Galilei wrongly attributed the tides to the sloshing of water caused by the Earth’s movement around the sun.

Sentinel-2 images of Tidal effects close to Augustus Island: a new island appears in low-tide conditions – Western Australia

Isaac Newton was the first scientist to correctly explain tides as the product of the gravitational attraction of astronomical masses. And from his theory the phenomenon was explained in 1740 by the French scientists Daniel Bernoulli, Leonhard Euler, Colin Maclaurin and Antoine Cavalleri and finally completed by Laplace in late 18th century.

Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of Earth. The effects are not equal throughout the Earth and there are areas where the tidal range can reach more than 130 cm. Amongst them we count Northern Australia and Atlantic Europe zones.

The M2 Tidal constituent. The colors indicate where tides are most extreme (highest highs, lowest lows), with blues being least extreme.

Copernicus Sentinel-2 images acquired few days apart show the surprising effect of the tides on the areas where the tidal ranges are more accentuated. Difference in the shorelines can be detected at very high resolution.

Sentinel-2 images of Mont Saint Michel – Normandy, probably the most famous tides-affected place on earth.


Sentinel-2 images of Jersey Island – English Channel


Credits: [Tides: A Scientific History, David Edgar Cartwright] – Wikipedia.

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