Behind the Forecast: ‘Dent’ in Earth’s magnetic field may impact satellites

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Published: Aug. 21, 2020 at 9:06 AM EDT
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LOUISVILLE, Ky. (WAVE) - Usually, these Science Behind the Forecast segments focus on things happening in the troposphere or on our planet's surface. Today, we're traveling into the exosphere, where satellites whip around Earth.

Our planet’s magnetic field protects us from charged particles from the sun hurtling towards us, trapping and repelling them. There is a weak spot in the field over South America and the southern Atlantic Ocean called the South Atlantic Anomaly (SAA). The SAA, which is basically a dent in the magnetic field, allows the sun’s particles to push closer to the Earth’s surface. It, however, does not have any significant impact on life on the ground. Recent data shows the SAA expanding west and further weakening. It has now also split into two lobs, according to a recent NASA statement.

More radiation bombards satellites as they pass through the SAA which can lead to severe impacts and even a complete shutdown.

The tilt of Earth's magnetic axis and the flow of molten metals within the outer core help to cause the Southern Atlantic Anomaly, according to the National Aeronautics and Space Administration.

Unlike with a typical magnet, the Earth's core magnetic field is not perfectly lined-up through the planet or stable. The motion of metals inside of the planet's outer core is like a generator, called the geodynamo, causing the electric currents that create our planet's magnetic field. These motions fluctuate, which means the magnetic fields fluctuate too.

This stereoscopic visualization shows a simple model of the Earth's magnetic field.
This stereoscopic visualization shows a simple model of the Earth's magnetic field.(NASA's Goddard Space Flight Center)

Low-Earth orbiting satellites, some of which are used in weather forecasting, can short-circuit when traveling through the South Atlantic Anomaly. This can lead to a temporary glitch or permanent damage. Satellite operators typically shutdown non-essential components when traveling through the SAA, according to NASA, to avoid damaging instruments or losing a satellite.

NASA launched the Ionospheric Connection Explorer (ICON) in 2019 to study our planet’s ionosphere, the layer of our atmosphere that overlaps with the boundary of space, including the SAA. Learning more about the South Atlantic Anomaly can help to ensure the safety of satellites in the future.

“Even though the SAA is slow-moving, it is going through some change in morphology, so it’s also important that we keep observing it by having continued missions,” Terry Sabaka, a geophysicist at NASA’s Goddard Space Flight Center, said in NASA’s statement. “Because that’s what helps us make models and predictions.”

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