A multi-disciplinary approach to investigate particle dynamics in the South Atlantic Magnetic Anomaly

The South Atlantic Anomaly (SAA) represents the minimum magnetic field intensity on Earth, influencing the energetic particle motion within the radiation belts, drawing them closer to our planet. The anomaly region serves as a key location for understanding the dynamics of the radiation belts affected by the magnetospheric response to solar activity.

Our investigation relied mainly on our recent numerical simulation results of the inner radiation belt during two magnetic storm events: May 15, 2005, and February 3-4, 2022. We developed a test particle simulation code to compute the 70-180 MeV proton trajectories in the inner magnetosphere. The IGRF and Tsyganenko models provided the background time-dependent electromagnetic field in response to the input solar conditions. The AP8 model and SAC-C satellite observation confirmed the numerical results. We summarize that protons tend to concentrate more in the SAA’s southern region, while further research found that electrons exhibit a higher tendency to populate the SAA’s northern region due to wave-particle interaction. In light of this conclusion, we identified prolonged Pc5 waves in the ground magnetic field data acquired from stations near the SAA’s northern region provided by MAGDAS/CPMN network.

Examining the particle dynamics inside the SAA is crucial for predicting the radiation environment of LEO missions, forecasting the thermosphere’s response to intense space weather, and anticipating the possible long-term climate changes.