Swarm tracks the elusive oceanic magnetism

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In search of that elusive magnetic signal. Credit: European Space Agency

The magnetic field is arguably one of the most mysterious characteristics of our planet. ESA’s Swarm mission continually gives more insight into how our protective shield is generated, how it behaves, and how it evolves. Adding yet another string to its bow, Swarm now tracks changes in the magnetic field produced in the oceans in greater detail than ever before.

New results from the Swarm satellite trio impress this year’s European Geoscience Union meeting in Vienna, Austria. This week-long event attracts scientists from all over the world to share their discoveries on our planet.

Today the spotlight is on Swarm, and a particular highlight is the way the mission tracks one of Earth’s most elusive sources of magnetism.

While the magnetic field is created largely by an ocean of superheated, swirling liquid iron in the planet’s outer core, other factors, such as magnetized rocks in the crust and the flow of the ocean, also affect the field.

We wouldn’t normally think of seawater as a source of magnetism, but it makes little contribution.

When the salt water in the ocean passes through the Earth’s magnetic field, an electric current is generated, which in turn induces a magnetic signal.

However, the field generated by the tides is tiny and extremely difficult to measure – but Swarm has done it in remarkable detail.

The animation above shows how the magnetic tide signal changes over 24 hours.







When the salt water in the ocean passes through the Earth’s magnetic field, an electric current is generated, which in turn induces a magnetic signal. However, the field generated by the tides is tiny – and extremely difficult to measure, but ESA’s Swarm mission did it in remarkable detail. Swarm was used to measure magnetic tidal signals from the ocean surface to the seabed, which provides a holistic picture of how the ocean is flowing at all depths. The magnetic tidal signal measured by Swarm is important for ocean and climate modeling, and is used to determine the electrical properties of the Earth’s lithosphere and upper mantle. Credit: Planetary Visions (credit: ESA / Planetary Visions)

Nils Olsen, Technical University of Denmark, said: “We used Swarm to measure magnetic tidal signals from the ocean surface to the seabed, giving us a really big picture of how he ocean flows to all depths – and this is new.

“As the oceans absorb heat from the air, it’s important to follow how that heat is distributed and stored, especially at depth, to understand how our climate is changing.







Swarm is ESA’s premier Earth observation satellite constellation. The three identical satellites are designed to accurately measure magnetic signals that originate from the Earth’s core, mantle, crust and oceans, as well as its ionosphere and magnetosphere. Carrying a multitude of sophisticated instruments, the constellation is essential for measuring and separating the various sources of magnetism and for creating models with unprecedented detail and precision. The fact that Swarm is a constellation also means that, for the first time, the conductivity of the mantle can be mapped in 3D from space. Satellites also offer a new way to study the effect solar particles have near Earth. Credit: ESA / AOES Medialab

“Additionally, because this magnetic tidal signal also induces a weak magnetic response deep beneath the seabed, these results will be used to learn more about the electrical properties of the Earth’s lithosphere and upper mantle.”

In addition to shedding this new light on magnetic tides, Swarm has also provided a new map of the magnetic field generated by the earth’s crust.


Magnetic Oceans and Electric Earth


Provided by the European Space Agency


Quote: Swarm Tracks Elusive Oceanic Magnetism (2018, April 10) retrieved October 24, 2021 from https://phys.org/news/2018-04-swarm-tracks-elusive-ocean-magnetism.html

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