Concerning? Is this just a long-term fluctuation/oscillation or a long-term trend?
Fact is we have only 11 years of detailed data. Not enough!
"A growing dent in Earth’s magnetic field, known as the South Atlantic Anomaly, has expanded by an area half the size of Europe over the past decade, according to new satellite data.
Stretching between South America and Africa, the anomaly has significantly grown since 2014, raising concerns for satellites, astronauts, and high-altitude flights due to increased radiation exposure.
Scientists believe that shifting flows of molten iron beneath the Earth’s surface, possibly influenced by a massive subterranean “hot blob” under Africa, are warping the Earth’s magnetic field. ..."
From the highlights and abstract:
"Highlights
• The Swarm satellite mission provides a high precision, absolute accuracy, global record of Earth’s magnetic field now spanning more than 11 yrs.
• Weak magnetic field region in the South Atlantic has expanded between 2014 and 2025.
• Canadian strong field region decreased in area while the corresponding Siberian region increased between 2014 and 2025.
• Evolution of Earth’s surface field originates in the large-scale field at the core-mantle boundary.
Abstract
The Swarm satellite trio has provided global vector magnetic field measurements, with high precision and absolute accuracy, for the past eleven years. Based on this consistent, high quality, dataset we describe here how Earth’s main (core-generated) magnetic field has evolved between 2014.0 and 2025.0.
At the Earth’s surface, we find that the region in the South Atlantic where the field strength is weakest (below 26,000 nT), has expanded by 0.9% of Earth’s surface area and that the minimum intensity has decreased by 336 nT from 22,430 nT to 22,094 nT.
In the northern polar region, we find that in Canada the area of strong field (above 57,000 nT) has diminished, decreasing in size by 0.65% of Earth’s surface area and with the maximum field strength decreasing by 801 nT from 58,832 nT to 58,031 nT. In contrast the corresponding strong field region in Siberia has grown in size, increasing in area by 0.42% of Earth’s surface area, with the maximum field intensity increasing by 260 nT from 61,359 nT to 61,619 nT.
At the core-mantle boundary, reversed flux features under southern Africa have moved westward, converging towards reversed flux features that have moved eastwards under the mid-Atlantic.
In the northern polar region a strong flux feature under the Bering strait has moved westwards along the inner-core tangent cylinder. At low latitudes, under Indonesia and the western Pacific, field features have surprisingly moved eastwards. Field accelerations, including oscillations, are found to be most intense at low latitudes.
The Swarm mission has for the past decade been an essential source of global information on the changes taking place in Earth’s main magnetic field. Due to the long timescales of the underlying core processes, extending the mission lifetime for as long as possible, in particular for the higher satellite Swarm Bravo, is expected to yield further scientific insights. A long mission for Swarm Bravo would be an efficient means of ensuring that the present era of high quality geomagnetic observations from space continues as new missions come online."
Graphical abstract
Instruments used in the Swarm
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