CSES satellite tracks shifting South Atlantic anomaly and impact on solar cycle twenty five

by Riko Seibo
Tokyo, Japan (SPX) Nov 14, 2025
The South Atlantic anomaly represents the region of Earth's radiation belts with the highest particle concentrations and weakest geomagnetic shielding. This area poses risks to the electronics aboard low-Earth orbit satellites and to the health of astronauts.

Researchers from the Institute of High Energy Physics of the Chinese Academy of Sciences, together with the National Institute of Natural Hazards, analyzed data spanning six years from China's Seismo-Electromagnetic Satellite. Their study examined the movement of geomagnetic fields and high-energy proton levels across the anomaly throughout the ascent of Solar Cycle twenty five.

The analysis identifies that the core region of proton flux within the anomaly has drifted westward and northward over five years. Using double-Gaussian fitting, daytime northward drift rates measured point two nine degrees per year and westward drift rates were point three six and point three three degrees per year for day and night respectively. Lower-energy protons shifted faster than higher-energy particles, indicating an energy-dependent pattern. The observed drift direction matches the International Geomagnetic Reference Field model.

Low-energy protons presented double-peak distributions, while higher-energy protons displayed a single-peak, confirmed by long-term NOAA satellite observations. CSES and model comparisons exposed major east - west differences in geomagnetic field strength, with the Eastern Hemisphere strengthening and the Western Hemisphere weakening. As a result, magnetic shielding above the anomaly dropped and correlated proton fluxes increased in the anomaly core while decreasing at the outer edge.

The results show two driving factors: increased solar activity suppressed proton flux around the outer anomaly, while local geomagnetic weakening deepened proton penetration toward the center. From twenty nineteen to twenty twenty four, researchers noted a six percent reduction in affected area, with flux changes tied to solar radio output.

High-resolution CSES observations provided new empirical data for understanding particle behavior, radiation belt dynamics, and geomagnetic field evolution. These findings offer practical insight for satellite orbit planning and radiation countermeasures.

Research Report:Investigation of the South Atlantic Anomaly (SAA) by proton flux variabilities based on 6 years' CSES data