A significant weakening of the Earth”s magnetic field in the South Atlantic region, known as the South Atlantic Anomaly, has been a source of intrigue for scientists for over a century. Recent satellite data indicates that this weak spot has experienced rapid growth in the last eleven years, expanding by an area comparable to half of continental Europe. This information is detailed in a new study published in the journal Physics of the Earth and Planetary Interiors.
An international team of researchers conducted an analysis using data from the European Space Agency”s Swarm, a group of three identical satellites designed to monitor Earth”s magnetic signals. The insights gained from this research may enhance current magnetic models that are vital for navigation and the tracking of space weather, all while deepening our understanding of the interactions between the Earth”s internal layers.
The leading hypothesis suggests that a massive, swirling pool of molten iron located approximately 1,800 miles beneath the Earth”s surface in the outer core could be the primary driver of this magnetic field dip. However, this is just one of numerous factors contributing to the anomaly, and scientists are actively investigating additional elements that might be influencing this weakening.
According to Chris Finlay, a professor of geomagnetism at the Technical University of Denmark and lead author of the study, the behavior of the South Atlantic Anomaly is quite unpredictable as it continues to expand. “The South Atlantic Anomaly is not just a single block,” Finlay noted. “It is evolving differently in relation to Africa compared to South America. There is something unique occurring in this region that is intensifying the weakening of the magnetic field.”
Finlay further explained, “Typically, we anticipate magnetic field lines to emerge from the core in the southern hemisphere. Yet, beneath the South Atlantic Anomaly, we observe unexpected regions where the magnetic field is instead directed back into the core.”
In addition to the anomaly, data from the Swarm mission has revealed that the magnetic field is strengthening over Siberia while simultaneously weakening over Canada. Scientists believe that these complex shifts may be connected to the northern magnetic pole”s recent movement toward Siberia.
Understanding Earth”s magnetic field requires recognizing its complexity; it is not merely a simple dipole like a bar magnet. “It is only through satellites like Swarm that we can accurately map this structure and observe its changes,” Finlay said.
The European Space Agency plans to extend the Swarm mission beyond 2030, which will enable researchers to continue monitoring the unusual characteristics of the Earth”s magnetic field for many years ahead.
