Improvements in the 4D drift-resolved radiation belt code Salammbô 4D.

Since the beginning of the space age, radiation belts have been a subject of great interest to scientists and space industry stakeholders due to their highly energetic and dynamic nature, which poses hazards to both spacecraft and humans. In particular, during strong geomagnetic activity, the particle fluxes in the outer electron radiation belt can be enhanced a thousand times compared to quiet times. Therefore, it is crucial to understand their dynamics along with the physical processes behind it.

Physical models simulate the dynamics of magnetically trapped particles in the radiation belts based on the Fokker-Planck formalism with different levels of representation. The Salammbô 3D code has proven its effectiveness in forecasting and nowcasting radiation belt dynamics as well as assessing associated risks. To expand the modeled energy range and enable studies of internal charging, it exists the Salammbô 4D code. This drift-resolved code breaks the symmetry of drift motion and incorporates the effects of magnetospheric electric fields into the dynamic.

We present advancements to Salammbô 4D through upgrades to key physical processes. These upgrades enable a more realistic representation of low-energy particle dynamics in inner magnetosphere modeling. The improvements include several key advancements. First, the modeling of convective particle transport has been refined by incorporating a realistic electric field model. Second, a more accurate description of magnetopause shadowing has been introduced. Finally, an event-based and Magnetic Local Time (MLT)-dependent wave-particle interaction modeling has been implemented.