The weak spot in the Earth’s magnetic field, the region over the South Atlantic where the field strength is greatly reduced compared to its surroundings, has grown in continental Europe over the past 11 years.
Using data from satellites of the European Space Agency, scientists have revealed that the South Atlantic Anomaly has started the development of unusual patterns on the Earth’s border, and a group of scientists associate the strong internal development, and its bright rantle, the Core layer.
“The South Atlantic Anomaly is not just one block,” Chris Finlay, professor of geomagnetism at the Technical University of Denmark and lead author of the study, said in a statement. “There is something special happening in this region that is causing the field to weaken in a profound way.”
This is the place
Earth’s magnetic field is important to our life. It protects the earth from cosmic rays and acts as a shield for the solar wind, keeping our atmosphere stable and protecting liquid water and other gases from being destroyed by the scattering of particles emitted by the sun.
Scientists first identified the South Atlantic Anomaly, better known as the weak spot, in the late 1950s, when the first satellites began to measure the Earth’s magnetic field. Early observations revealed that radiation levels were unusually high somewhere over the South Atlantic, which meant that the magnetic field was weak compared to surrounding regions.
Satellites passing through the region receive higher doses of radiation compared to other areas, making the study of the anomaly an important part of maintaining the safety of space missions, according to ESA.
“Typically we expect to see magnetic field lines coming out of the ridge in the Southern Hemisphere,” Finlay said. “But under the South Atlantic Anomaly we see unexpected places where the magnetic field, instead of going out of the core, returns to the core.”
Swarm data revealed that one of these areas is moving from the west over Africa, causing an interesting Atlantic anomaly in this region. The data also highlights two points in the northern hemisphere where the Earth’s magnetic field is particularly strong, one around Canada and the other around Siberia, which has had its first effects.
The continental shelf around Canada is weak, shrinking to 0.65% of the Earth’s surface, about the size of India. On the other hand, the mighty region of Siberia has grown by 0.42% of the land area, or about the size of Greenland.
“When you’re trying to understand the Earth’s magnetic field, it’s important to remember that it’s not just a simple dipole, like a bar magnet,” Finlay said. “It is because of satellites like the swarm that we can completely map this structure and see it evolve.”
ESA’s satellite constellation was launched in 2013 to study the strength of the magnetic field. The mission uses three satellites, named Alpha, Bravo, and Charlie, to measure magnetic signals from the Earth’s core, as well as the planet’s crust, oceans, and parts of its atmosphere.
