After a four-year-long study on the ‘Swarm Mission’ by the European Space Agency (ESA), a second magnetic field has reportedly been discovered. ESA found this with the help of a trio of satellites, which have been studying Earth’s magnetic field. These satellites show details of the steady swell of a magnetic field produced by the ocean’s tides. This discovery is believed to be a big help in building better models around global warming.
“It’s a really tiny magnetic field,” Physicist Nils Olsen from the Technical University of Denmark told BBC. “It’s about 2 – 2.5 nanotesla at satellite altitude, which is about 20,000 times weaker than Earth’s global magnetic field.” Fundamentally, both fields are the result of a dynamo effect produced by charged particles being sloshed around in a fluid. The stronger magnetic field, which tugs on our compass needle, forms from the steady movement of molten rock deep under our feet.
“We have used Swarm to measure the magnetic signals of tides from the ocean surface to the seabed, which gives us a truly global picture of how the ocean flows at all depths – and this is new,” says Olsen.
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As water is capable of holding onto significant amounts of heat, predicting Earth’s ability to soak up excess warmth trapped by rising amounts of greenhouse gases relies on knowing precisely how tides and currents move in three dimensions. “In addition, because this tidal magnetic signal also induces a weak magnetic response deep under the seabed, these results will be used to learn more about the electrical properties of Earth’s lithosphere and upper mantle,” Olsen said.