Published:  12:23 AM, 12 April 2018

Earth's magnetic ocean tides mapped from space

Earth's magnetic ocean tides mapped from space

This is the European Space Agency's spectacular new view of ocean tides as they sweep around the Earth.The movie shows not the bulging movement of water directly, but rather its magnetic signature.

As the Moon pulls the salty seas through our planet's global magnetic field, electric currents are generated. And these currents then induce their own magnetic signals, which have now been mapped in exquisite detail by a trio of Esa satellites known as Swarm. It is a remarkable achievement because the effect is actually very small.

"It's a really tiny magnetic field. It's about 2-2.5 nanotesla at satellite altitude, which is about 20,000 times weaker than the Earth's global magnetic field," Nils Olsen, from the Technical University of Denmark, told BBC News.

The professor was speaking at the European Geosciences Union General Assembly (EGU) in Vienna, Austria, where a clutch of new Swarm results have been released. The mission was sent into orbit in 2013 to bring fresh insight on Earth's magnetic behavior.

Most of the global field is produced by convection of molten iron in the planet's outer core. But there are secondary components that contribute to the overall signal - such as that coming from the oceans.

Other satellites will sense the tides as a change in sea-surface height. What is different about the Swarm trio's magnetic view is that it reveals the movement of the entire water column, right down to the seabed.

This is important for climate studies. The oceans store and transport vast amounts of heat energy, and getting the more integrated perspective from Swarm enables scientists to build better models of the Earth system.


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