Versatile near-Earth environment of Radiation Belts and ring current 4D (VERB-4D) code

Ring current particles, which are heavily influenced by geomagnetic activity, excite plasmawaves (e.g., EMIC, chorus etc) and affect the terrestrial magnetospheric configuration, which modifies particle trajectories. During geomagnetic storms, specifically the recovery phase, the ring current becomes disturbed and decays via various loss processes (e.g., charge exchange, Coulomb collisions, and EMIC wave scattering). These disturbances in the ring current contribute significantly to the development of the Dst index. Since the ring current plays a crucial role in magnetospheric dynamics through its spatial and temporal evolution, understanding how it impacts the Dst index remains an ongoing topic of research.

In this study, we present the first simulation results of the ring current using the Versatile near-Earth environment of Radiation Belts and ring current - 4D (VERB-4D) code, previously known as the Versatile Electron Radiation Belt - 4D code. Our simulations are compared to the Van Allen Probes HOPE and RBSPICE during a geomagnetic storm on March 17, 2013. We study the evolution of the MLT-resolved and average Dst index during the storm‘s recovery phase while examining the relative contributions of charge exchange, Coulomb drag, and radial diffusion.