Earth’s Magnetic Field Shows Intensifying Weakness in South Atlantic Anomaly
Recentโ data from ESA’s Swarm satellite constellation reveals a important expansion of โคthe South โAtlantic Anomaly (SAA), a region where Earth’s magnetic field is unusually weak,โค since 2014. A โstudy published in Physics of the Earth and โขPlanetary Interiors linksโ this development to unusual activity at theโ boundary betweenโ Earth’s liquid outer core and its rockyโ mantle.
The SAA was first identified in theโ late 1950s with the advent of satellite-basedโฃ magnetic fieldโ measurements. Satellites passingโ throughโ this area โขexperience elevated levels of radiation, posing a challenge toโฃ the safety andโฃ operation of space missions.
According to Chrisโฃ Finlay, professor โขof geomagnetism at the Technical University of Denmark and lead author of the study, โคthe SAA isn’t a uniform weakness. “There’s something special happening โin this region that is causing the fieldโค to weaken in a more intense way,” he stated. Specifically, Swarm data indicates that, unlike typical magneticโ field patternsโ where lines emerge โfrom the core in the southern hemisphere, the SAA exhibits areas where the magnetic field re-enters โฃ the core. One such area is currently moving westward over โขAfrica, contributing to โคthe anomaly’s growth.
While the SAA is intensifying, changes are also occurring in areas ofโ magnetic field strength. A strong โregion over Canada has weakened, shrinking โby 0.65% of โEarth’s surface area – an area nearly the โขsize of India. Conversely, a strong region over Siberiaโข has โคgrown by โ0.42%, roughly the size โof โขGreenland.
Earth’s magnetic field is vital for life, shielding the planet fromโฃ harmful cosmic radiation and solar wind, and protecting the atmosphere. The Swarm mission,โข launched in 2013, utilizes three satellites – Alpha, Bravo, and Charlie – toโค map the complex โstructure of the magnetic field, originatingโ from the core, crust, oceans, โขand atmosphere, and track its dynamicโ changes.Finlay emphasizes that understanding Earth’s magneticโ field requires โคrecognizing โits complexity,stating,”It’s only byโข having satellites like Swarm that we can fully map this structure and see itโ changing.”
