Space Physics Seminar winter-2016

The Versatile Electron Radiation Belt (VERB) code: Long-term simulations during the Van Allen Probes mission

The Versatile Electron Radiation Belt (VERB) code solves the Fokker-Planck equation, taking into account radial diffusion and local pitch-angle, energy and mixed scattering. Using the VERB code, we performed several long-term simulations during the first year of the Van Allen Probes mission. We considered the energetic (>300 KeV), relativistic (~1 MeV) and ultra-relativistic (>3 MeV) electrons. The measurements of the energetic and relativistic electrons were well reproduced by the simulation during a period of various geomagnetic activity. However, for ultra-relativistic energies, the VERB code simulation significantly overestimates the observations. Since the additional losses were required only at very high energies, we concluded that EMIC waves are the most likely additional source of scattering to explain the observed decay rates. We included various parameterizations of the long-term EMIC waves based on the solar wind parameters and geomagnetic indexes, and found that simulation with EMIC waves provided a better agreement with the observations.