European Space Agency satellite uses gravity map to track ocean currents

The map is of great use for ocean monitoring and forecasting systems

 
By Aditya Misra
Published: Saturday 04 July 2015

Ocean currents from GOCE (image courtesy ESA)

Using data from various satellites, particularly European Space Agency’s GOCE, scientists have created what they claim is the world’s most accurate space view of global ocean currents and the speeds of their movement.

The Gravity field and steady-state Ocean Circulation Explorer, or GOCE, measured the minute changes in Earth's gravitational pull which varies at different places due to the uneven distribution of mass inside the planet.

This data was used to create a geoid or “a hypothetical global ocean at rest”. It is the shape the oceans would take in absence of winds or tides. Comparing this geoid with measurements of sea surface height taken by other spacecraft, the areas where water has accumulated were located.

According to the European Space Agency (ESA) website, “the GOCE geoid was subtracted from the mean sea-surface height measured over a 20-year period by satellites, including ESA’s veteran Envisat. The result shows the mean dynamic topography of the ocean surface, showing higher- and lower-than-average water levels. Based on this map, ocean currents and their speeds were calculated and validated using in situ buoys.”

GOCE geoid. The colours in the image represent deviations in height (–100 m to +100 m) from an ideal geoid. The blue shades represent low values and the reds/yellows represent high values

The data is of great use in ocean monitoring and forecasting systems. “The new ocean current speed map is of particular interest to UNESCO’s Intergovernmental Oceanographic Commission, which supports the international cooperation and the understanding and management of oceans and coastal areas,” says the ESA website.

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