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(06.01.2021)
We know that the Earth’s magnetic field has decayed by about 5% per century since measurements began in 1840. And much of that decay is associated with a strangely weak spot between South America and southern Africa, known as the South Atlantic Anomaly. This patch has grown over the last 250 years and today the weak field messes with satellite technology.
(22.05.2020)
According to the European Space Agency (ESA), the magnetic field has lost around 9 percent of its strength over the preceding two centuries. One section of the magnetic field has been found to have weakened considerably since 1970.
This patch, called the South Atlantic Anomaly, sits between Africa and South America. Over the last 50 years, it has grown and moved farther west at a rate of roughly 12 miles per year.
(17.08.2020)
Earth’s magnetic field acts like a protective shield around the planet, repelling and trapping charged particles from the Sun. But over South America and the southern Atlantic Ocean, an unusually weak spot in the field – called the South Atlantic Anomaly, or SAA – allows these particles to dip closer to the surface than normal. Particle radiation in this region can knock out onboard computers and interfere with the data collection of satellites that pass through it – a key reason why NASA scientists want to track and study the anomaly.
The South Atlantic Anomaly is also of interest to NASA’s Earth scientists who monitor the changes in magnetic field strength there, both for how such changes affect Earth’s atmosphere and as an indicator of what’s happening to Earth’s magnetic fields, deep inside the globe.
(18.08.2020)
Scientists at NASA are investigating the mysterious South Atlantic Anomaly, a region of weakness in the Earth’s magnetic field that is growing in size.
On average, the planet’s magnetic field has lost almost 10% of its strength over the last two centuries – but there is a large localised region of weakness stretching from Africa to South America.
Archaeomagnetism, the application of paleomagnetic methods to archaeological materials, is interdisciplinary not only in its methods but also in its impact. Well-dated archaeological materials are a critical data source for geomagnetic secular variation models [1–6], which are used to explore the dynamic structure of Earth’s core [7, 8], the rates of cosmogenic isotope production in the atmosphere [9–11] and the possible effect of geomagnetism on climate [11–13]. Precise documentation of the ancient field also helps contextualize geomagnetic observations from the modern era, such as the evolution of the South Atlantic Anomaly [14, 15] and the ongoing decline in the field’s intensity [16–18].
Albert Einstein once called the behavior of the magnetic field one of the great mysteries of physics, but understanding and possibly predicting its changes has taken on a new urgency for scientists. The field has lost around 10 percent of its strength since measurements began less than 200 years ago, leading some researchers to question whether we are on the way to a flip in polarity, which would be preceded by a loss of our precious shield against cosmic radiation.
(31.10.2018) There was no fire; it was a radiation phantom, playing tricks with the satellite’s highly sensitive instruments.
As Voiland’s piece notes, algorithms are designed to filter out these curiosities, but every now and then, a few can slip through, resulting in some rather fascinating ghosts in the machine.
(14.7.2017) “It is almost certainly SAMA,” Oliva said, using an acronym for the South Atlantic Magnetic Anomaly. This weakness in Earth’s magnetic field, centered over South America and the South Atlantic, allows one of Earth’s Van Allen radiation belts—zones of energetic particles trapped by the magnetic field—to dip closer to the atmosphere. As a result, much of South America and part of the South Atlantic Ocean get an extra dose of radiation.