Scientists have detected a brand new type of magnetic wave that travels through Earthfrom the outer core every seven years, thereby distorting the strength of our planet’s magnetic field.
Waves – nicknamed “Magneto-Coriolis” waves because they travel along the Earth’s axis of rotation, according to the Coriolis effect – creep from east to west in tall columns that can travel up to 930 miles (1,500 kilometers) per year, the researchers wrote in a March 21 article in the journal Proceedings of the National Academy of Sciences. Using a fleet of European Space Agency (ESA) satellites, the team identified the mysterious waves all the way to the outermost layer of Earth’s liquid outer core, just where this layer meets the rocky mantle – about 1,800 miles (2,900 km) below the planet’s surface.
The existence of these waves could help explain the planet’s mysterious fluctuations, researchers say. magnetic fieldwhich is generated by the movement of the liquid the iron in the outer core of the planet. Satellite measurements of the magnetic field taken over the past 20 years show that the intensity of the field decreases approximately every seven years, coinciding with the oscillations of these new waves.
“Geophysicists have long theorized the existence of such waves, but they were thought to occur on much longer time scales,” said the study’s lead author, Nicolas Gillet, a researcher at the University. Grenoble Alps in France. said in a press release. “Our research suggests that other waves of this type are likely to exist, probably with longer periods – but their discovery relies on further research.”
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The heart of the matter
Earth’s outer core is an orb of molten iron that bubbles and ripples with constant motion. The flow of this rotating electrically conductive fluid is believed to be the source of Earth’s magnetic shield, which wraps around the planet and extends hundreds of thousands of miles into space, protecting the Earth from harmful radiation.
The planet’s magnetic field is constantly changing, both short and long term. In the long term, the magnetic field was gradually weaken for hundreds of years. Recent measurements taken by ground and satellite instruments also show regular variations in the strength and shape of the magnetic field that occur every few years.
Scientists have long believed that these short-term variations in field strength are influenced by activity in the planet’s outer core. This new study may provide the long-sought proof.
The study authors reviewed more than 20 years of magnetic field data, collected by ESA’s Swarm satellite mission between 1999 and 2021. Swarm is a fleet of three identical satellites deployed to measure magnetic signals from the core , crust, oceans and atmosphere of the Earth. The team combined this satellite data with previous magnetic field measurements taken by ground-based sensors, then used a computer model to simulate the geodynamo, or the convective flow of fluid in the Earth’s outer core.
Thanks to these combined measurements, the team identified for the first time the presence of magneto-Coriolis waves in the core of the planet.
The source of these waves remains a mystery for now, but they likely come from “deep Earth disturbances”. [outer] heart,” Gillet said.
It’s also likely that these waves aren’t the only ones oscillating across the core-mantle boundary, Gillet added. While magneto-coriolis waves explain some of the seven-year magnetic field fluctuations observed by Swarm and other sensors, other yet unknown waves with even longer periodicities could explain magnetic field variations over timescales longer, said Gillet. To discover such waves, researchers will only have to keep their eyes on the nucleus.
Originally posted on Live Science.
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