The Earth is surrounded by the Van Allen radiation belts, which are regions filled with highly energetic electrons. These radiation belts were among the first discoveries of the space age and they remain one of the most fascinating and challenging phenomena in space science. At the same time, they pose a serious risk to satellites and to humans working in space because energetic radiation can damage electronic systems and affect human health.
The radiation belts often show dramatic dropouts, particularly during geomagnetic storms, during which the number of energetic electrons decreases by several orders of magnitude within very short time periods. In some cases, these decreases happen faster than the time it takes a satellite to complete one orbit around Earth. Although such events have been observed for many years, the physical processes responsible for these electron losses are still not fully understood, and their relative importance has not yet been quantified. There are two main mechanisms that are suggested to be responsible for these losses: 1) the scattering of electrons by electromagnetic ion cyclotron (EMIC) waves (Kennel & Thorne, 1971), which can lead electrons into Earth’s atmosphere, and 2) the outward radial diffusion, where electrons are transported towards the magnetopause, and escape into space (Shprits et al., 2006).
The overarching goal of this project is to understand the causes of these electron dropouts at different energies and to determine how strongly each of the two mechanisms contributes under varying space weather conditions. To achieve this goal, we will combine the expertise of GFZ Potsdam, TU Braunschweig, and Institute of Atmospheric Physics IAP, Prague, to develop models of EMIC waves and of the position and variability of the magnetopause. These models will be integrated into the Versatile Electron Radiation Belt (VERB) simulation code. Sensitivity experiments will allow us to quantify how the two main loss mechanisms affect the dynamics of radiation belt electrons at different energies. Detailed validation of the simulation results against satellite observations will help us determine whether additional physical loss processes are needed to explain any remaining differences between the model predictions and real measurements.
By improving our understanding of how and why electrons are lost from the radiation belts, this project will help to explain the dynamics of these belts in different space weather conditions. The results will provide a more complete picture of how the belts respond to geomagnetic storms and allow for better assessment of the risks they pose to satellites and space missions.
Project duration: 07/2025 – 06/2028
Funding: German Research Foundation (DFG)
Principal Investigator at GFZ: Prof. Dr. Yuri Shprits
Collaboration: Technische Universität Braunschweig; Institute of Atmospheric Physics, Czech Academy of Sciences