A puzzling and significant dip in the Earth”s magnetic field, located over the South Atlantic, has been the subject of scientific inquiry for more than a century. This region, known as the South Atlantic Anomaly, has seen a remarkable increase in size over the past eleven years, according to satellite observations.
Recent findings published in the journal Physics of the Earth and Planetary Interiors indicate that this weak spot has expanded to cover an area approximately half the size of continental Europe. An international team of researchers utilized data from the European Space Agency”s Swarm, a trio of identical satellites designed to monitor the Earth”s magnetic signals.
The expansion of the anomaly could enhance our current magnetic models, which are vital for navigation and understanding space weather. Furthermore, it may provide insights into the interactions between the Earth”s layers. Scientists speculate that a massive, swirling mass of molten iron located about 1,800 miles beneath the Earth”s surface might be responsible for this significant decrease in magnetic strength. However, this is merely one potential factor among many that influence the anomaly”s behavior.
Lead author and professor of geomagnetism at the Technical University of Denmark, Chris Finlay, noted that the anomaly exhibits surprising characteristics as it continues to grow. “The South Atlantic Anomaly is not just a single block,” Finlay explained. “Its behavior varies between Africa and South America, indicating that unique phenomena are occurring in this region, resulting in an intensified weakening of the magnetic field.”
Further elaborating on this, Finlay stated, “Typically, we expect to see magnetic field lines emanating from the core in the southern hemisphere. However, under the South Atlantic Anomaly, we observe unexpected zones where the magnetic field appears to be retreating back into the core.”
In addition to studying the anomaly, Swarm data has revealed that the magnetic field is strengthening over Siberia while simultaneously weakening in Canada. These complex shifts are thought to be related to the northward drift of the magnetic pole toward Siberia in recent years.
Finlay emphasized the importance of understanding Earth”s magnetic field, stating, “It”s crucial to remember that the magnetic field is not a simple dipole like a bar magnet. The use of satellites like Swarm allows us to map this structure comprehensively and observe its changes over time.”
Looking ahead, the European Space Agency plans to extend the Swarm mission beyond 2030, which will enable researchers to continue monitoring the unusual dynamics of our planet”s magnetic field for the foreseeable future.
