Monitoring the dynamic shape of the sea surface

Today’s Video of the Day from the European Space Agency describes the importance of monitoring the shape of the sea surface, which is constantly changing. These observations have many applications, such as ship routing, ocean current forecasting, and debris tracking.

“A project supported by the Discovery element of ESA’s Basic Activities recently investigated a new technique to measure sea surface topography very precisely,” reports ESA.

“The technique involves looking at satellite navigation (GNSS) signals that have been reflected off of the sea surface at very low angles. At these so-called grazing angles, waves and surface roughness have very little impact on the reflection process; the sea surface acts as a very smooth mirror.”

Estel Cardellach is the principal investigator at the Institute for Space Studies of Catalonia, who first submitted the idea for the project.

“In a mirror-like reflection the phase of the signal can be tracked – it is continuous,” said Cardellach. “Different surface heights result in different phase measurements. It gives a very precise measurement of the surface altitude at a few centimetres’ precision.”

The researchers developed a GNSS receiver and set up an experiment in the Balaeric Islands to collect signals from the receiver that were reflected off the sea surface. Ultimately, these signals will provide improved measurements of the shape of the sea surface.

Image/ Video Credit: ESA

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By Chrissy Sexton, Earth.com Staff Writer