Energetic, Relativistic and Ultra-Relativistic Electrons: Comparison of Long-term VERB Code Simulations with Van Allen Probes Measurements

Wednesday, 17 December 2014: 11:38 AM
Alexander Drozdov1,2, Yuri Shprits1,3, Ksenia Orlova1,2, Adam C Kellerman1, Dmitriy Subbotin1, Daniel N. Baker4 and Harlan E. Spence5, (1)University of California Los Angeles, EPSS, Los Angeles, CA, United States, (2)Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, Moscow, Russia, (3)MIT, Skoltech, Cambridge, MA, United States, (4)University of Colorado, Laboratory for Atmospheric and Space Physics, Boulder, CO, United States, (5)University of New Hampshire Main Campus, Durham, NH, United States
In this study, we compare long-term simulations performed by the Versatile Electron Radiation Belt (VERB) code with observations from the MagEIS and REPT instruments on the Van Allen Probes. The model takes into account radial, energy, pitch-angle and mixed diffusion, losses into the atmosphere, and magnetopause shadowing. We consider the energetic (>100 KeV), relativistic (~0.5-1 MeV) and ultra-relativistic (>2 MeV) electrons. One year of relativistic electron measurements (μ=700 MeV/G) from October 1, 2012 to October 1, 2013 are well reproduced by the simulation during a period of the various geomagnetic activity. However, for ultra-relativistic energies (μ=3500 MeV/G), the VERB code simulation overestimates electron phase space density (PSD). These results indicate that an additional loss mechanism is operational and efficient for these high energies. We discuss possible solutions for improving the modeling of the radiation belts dynamics.