The European Space Agency's Gravity and Ocean Circulation Explorer satellite reentered the Earth's atmosphere and burned up in 2013 after four years and eight months in orbit. But though GOCE is no more, its treasure trove of data is helping scientists to create the most accurate maps so far of global ocean currents.
At at a UN conference Thursday in Paris, scientists revealed how the satellite's ultra-precise measurements of the Earth's gravity enabled them to create a simulation of the Earth's oceans at rest, so that they could observe the effects of gravity upon ocean currents. In real life, the gravity-current relationship is tougher to chart with accuracy, because other forces, such as wind, cause currents to deviate from the pattern established by gravity.
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The new, more precise model is valuable for understanding the planet's climate. The oceans transport about 30 percent of the Earth's heat, and the circulation of ocean waters plays an important role in climate regulation by transporting heat from low to high latitudes in surface waters, while currents cooled at high latitudes flow in deeper waters back toward the equator.
The Gulf Stream, which carries warm surface waters northward from the Gulf of Mexico, is a good example of that effect. Thanks to this current, the coastal waters of Europe are actually slightly warmer than waters at equivalent latitudes in the North Pacific.
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GOCE measured subtle changes in Earth's gravitational pull, which varies from place to place because of the uneven distribution of mass inside the planet, as a BBC News article explains.
"GOCE has really made a breakthrough for the estimation of ocean currents," Marie-Helene Rio from the Italian National Research Council's Institute of Atmospheric Sciences and Climate told the BBC.