South Atlantic Anomaly (SAA)

18.10.2025

1. South Atlantic Anomaly (SAA)

Context

Recent findings from the European Space Agency’s (ESA) Swarm Mission reveal that the South Atlantic Anomaly (SAA),  the weakest zone of Earth’s magnetic field — has expanded by about 0.9% since 2014. This region spans South America, the southern Atlantic Ocean, and parts of southwest Africa, posing challenges to satellites and spacecraft traversing it.

What It Is

• The South Atlantic Anomaly represents an area where Earth’s magnetic field intensity is considerably lower than average.
•  This anomaly arises from irregular movements of molten iron and nickel in Earth’s outer core, which distort the planet’s geo-dynamo system — the process responsible for generating the global magnetic field.
•  Beneath this zone, reverse magnetic flux patches cause field lines to loop back into Earth’s core, reducing magnetic strength near the surface.

Key Features

• Location: Extends over South America, southern Atlantic Ocean, and southwest Africa.
   
• Expansion: Increased by 0.9% since 2014, gradually shifting westward.
   
• Dual-Cell Structure: Since 2020, the anomaly has split into two sub-cells,  one near South America and another near southwest Africa, indicating evolving geomagnetic patterns.
   

Impacts

1. Satellite Vulnerability

Spacecraft passing through the SAA experience enhanced radiation exposure, which can damage onboard electronics, sensors, and data storage systems.

2. Disruption in Low-Earth Orbit Operations

Satellites and instruments relying on precise calibration and navigation systems face signal distortion or data loss when traversing this weak magnetic region.

3. Increased Space Weather Risks

Weakened magnetic shielding allows more charged solar particles to penetrate, intensifying space weather hazards for communication, navigation, and Earth-observing satellites.

Monitoring and Research

• ESA’s Swarm constellation, comprising three satellites, continues to observe Earth’s magnetic field and monitor changes in the SAA.
•  Ongoing data collection through 2030 aims to better understand core dynamics, predict anomaly evolution, and safeguard space missions against radiation-induced malfunctions.

Conclusion

The South Atlantic Anomaly highlights the dynamic nature of Earth’s magnetic field and its implications for modern technology.
 Continuous satellite monitoring, improved spacecraft shielding, and predictive modeling are essential to mitigate risks and ensure the reliability of global communication and observation systems in a changing magnetic environment.