South Atlantic Ocean Anomaly: Causes, Impacts, and Recent Findings

Illustration (Science ABC)

YOGYAKARTA - The South Atlantic Anomaly (SAA) is one of the geomagnetic phenomena that attracts the attention of scientists the most because it has a major impact on the safety of space technology. This phenomenon describes a large area above the South Atlantic Ocean where the Earth's magnetic field is significantly weakened.

This weakening of magnetic protection triggers an increase in radiation that can affect satellite work. This condition has recently worsened. The following will discuss what the South Atlantic Ocean Anomaly is, its causes, its impact, and the latest findings.

What is the South Atlantic Anomaly?

The South Atlantic Ocean Anomaly (SAA) is a region of weakening of the Earth's magnetic field that forms over the South Atlantic and South American areas. The Earth's magnetic field serves as a protective shield from cosmic rays and charged particles from the Sun.

When the magnetic field weakens in certain regions, the protection is reduced so that radiation can reach low altitudes. As a result, satellites passing through these regions face higher radiation doses than usual.

Quoting The Europian Space Agency, this phenomenon has been known since the 19th century after scientists identified a weakening of magnetism in southeast South America. Over time, this weak area has expanded and is now getting wider, even reaching almost half the size of the European continent based on the latest data.

Causes of the South Atlantic Anomaly

The main cause of the weakening of the magnetic field in the South Atlantic region is the complex dynamics that occur in the Earth's outer core consisting of liquid iron. The movement of this liquid iron produces electric currents that give rise to the global magnetic field. However, the flow pattern is not uniform so that some areas experience weakening.

One of the scientific explanations is the existence of "reverse flux patches". Reverse flux patches are areas where the magnetic field lines do not exit the Earth's core as usual, but instead go back in.

"Normally we would see lines of magnetic fields coming out of the Earth's core in the southern hemisphere. However, under the South Atlantic Ocean Anomaly, we see an unexpected area where the magnetic field, instead of coming out of the core, actually goes back to the core," explained Professor Chris Finlay from the Technical University of Denmark.

This unusual pattern creates disturbances in the magnetic structure which weakens the field at the surface.

Important Findings from the Swarm Satellites

The ESA's Swarm satellite constellation has been collecting magnetic field data for more than 11 years since its launch in 2013. These satellites are designed to measure magnetic signals from the Earth's core, mantle, crust, as well as the ionosphere and magnetosphere. Thanks to the data, scientists can observe long-term changes that were previously undetectable.

Swarm observations reveal that the South Atlantic Ocean Anomaly has continued to expand from 2014 to 2025. Its size is now almost half the size of the European continent, indicating a significant weakening of the magnetic field. In addition, new weakening areas are emerging faster in the southwest of Africa.

The report in the journal Physics of the Earth and Planetary Interiors, reveals the latest results from the Swarm mission that the region in the Atlantic Ocean in the southwest of Africa has experienced an even faster weakening of the Earth's magnetic field since 2020.

Impacts of the South Atlantic Anomaly on Satellite Technology

Satellites that pass through the South Atlantic Ocean Anomaly risk experiencing electronic interference due to increased radiation. High radiation can cause sensor damage to hardware failure. Some satellites even turn off certain devices when entering this region as a preventive measure.

In addition, changes in magnetic field dynamics can affect global navigation. Many navigation and mapping systems rely on accurate magnetic field models. Swarm data helps update these models so that navigation remains precise even if the magnetic field changes.

So that's the discussion of the South Atlantic Anomaly, follow other interesting articles on VOI.ID. So as not to miss the latest news, follow and monitor our social media accounts!