South Atlantic anomaly

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The Earth's magnetic dipole axis, shifted from the center of the earth, illustrates SAA
Weak geomagnetic field at the location of the SAA
Increased radiation exposure in the area of ​​the South Atlantic Anomaly. The picture shows the spatially resolved count rate of protons with an energy of 30 to 80 keV, measured by a NOAA satellite at an altitude of 850 km.

The South Atlantic Anomaly ( English South Atlantic anomaly , SAA) is a region of enhanced radiation activity associated with a regional magnetic anomaly likely to be related. Its center is off the coast of Brazil , approximately at 40 ° west and 30 ° south.

The Van Allen radiation belt surrounds the earth at a distance of several hundred kilometers. In the area of ​​the South Atlantic Anomaly, it comes much closer to it. Low-flying satellites with an inclination between 35 ° and 60 ° are exposed to higher particle radiation of protons and electrons. Ionizing radiation is also increased on the earth's surface .

The SWARM satellite mission launched by ESA in 2013 is intended to research and measure the expanding and deepening South Atlantic anomaly more precisely than before.

As early as 1830, Alexander von Humboldt observed the reduced strength of the Earth's magnetic field over the southern Atlantic (see picture above right). One reason for this is that the dipole axis of the magnetic field does not run through the geocenter (center of the earth), but around 450 km in the direction of 140 ° east longitude (approx. To New Guinea ) - i.e. opposite to the geographic longitude of the South Atlantic anomaly.

The South Atlantic Anomaly is currently migrating westward at 0.3 ° per year. The speed is on the order of the differential rotation of the earth.

Web links

Commons : South Atlantic Anomaly  - collection of images, videos, and audio files

Individual evidence

  1. ↑ SWARM satellite mission - press release by the European Space Agency ESA.

Coordinates: 30 ° 0 ′ 0 ″  S , 40 ° 0 ′ 0 ″  W.