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Simulation of the acceleration of relativistic electrons in the inner magnetosphere using RCM-VERB coupled codes

Subbotin D. A., Y. Y. Shprits, M. Gkioulidou, L. R. Lyons, B. Ni, V. G. Merkin, F. R. Toffoletto, R. M. Thorne, R. B. Horne, M. K. Hudson, (2011), Simulation of the acceleration of relativistic electrons in the inner magnetosphere using RCM-VERB coupled codes, J. of Geophys. Res. [Space Physics], 116, doi:10.1029/2010JA016350

Abstract

Radiation belt dynamics have been modeled by the modified Fokker-Planck diffusion equation with sources from the low-energy plasma sheet population and losses to the atmosphere and magnetopause. We perform a coupled simulation of the Rice Convection Model (RCM) and Versatile Electron Radiation Belt (VERB) code. The RCM models magnetospheric convection and provides a low-energy electron seed population for the VERB diffusion code simulations of the Earth's radiation belts. VERB simulations are driven by the realistic time-dependent electron seed population and by the Kp index, which is used to specify rates of diffusion by ultralow frequency (ULF) and very low frequency wave activity and, therefore, diffusion processes. Radial diffusion is produced by ULF waves, while pitch angle and energy diffusion are produced by chorus waves outside the plasmasphere and by hiss waves inside the plasmasphere. The results of the simulation indicate that storm time enhanced magnetospheric convection combined with radial diffusion can bring electrons with tens of keV energy close to the Earth and can affect electron fluxes at 3–4 RE. These electrons can be further accelerated locally by chorus waves to MeV energies. Furthermore, outward radial diffusion smooths out the peak of the high-energy fluxes and produces MeV electron enhancement around geosynchronous orbit (6–7 RE) despite the absence of local electron acceleration in that region. Our coupled simulations indicate that local acceleration in the inner magnetosphere may be a dominant source of relativistic electrons that reach geosynchronous orbit.

Authors (sorted by name)

Gkioulidou Horne Hudson Lyons Merkin Ni Shprits Subbotin Thorne Toffoletto

Journal / Conference

Journal Of Geophysical Research (Space Physics)

Acknowledgments

This research was supported by the NASA grant NNX09AF51G, NSF GEM grant ATM‐0603191, AFRL grant FA9550‐08‐1‐0140, and lab Research Fee grant 09‐LR‐04‐200 116720‐SHPY. The work by Larry R. Lyons and M. Gkioulidou has been supported by NASA grants NNX07AF66G and NNX09AQ41H and NSF grant ATM‐0819864.

Grants

09‐LR‐04116720 ATM‐0603191 ATM‐0819864 FA9550‐08‐1‐0140 NNX07AF66G NNX09AF51G NNX09AQ41H

Bibtex

@article{doi:10.1029/2010JA016350,
author = {Subbotin, D. A. and Shprits, Y. Y. and Gkioulidou, M. and Lyons, L. R. and Ni, B. and Merkin, V. G. and Toffoletto, F. R. and Thorne, R. M. and Horne, R.B. and Hudson, M. K.},
title = {Simulation of the acceleration of relativistic electrons in the inner magnetosphere using RCM-VERB coupled codes},
year = {2011},
journal = {Journal of Geophysical Research: Space Physics},
volume = {116},
number = {A8},
pages = {},
keywords = {RCM, VERB, magnetospheric convection, modeling, models coupling, radiation belts},
doi = {10.1029/2010JA016350},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2010JA016350},
eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2010JA016350},
abstract = {Radiation belt dynamics have been modeled by the modified Fokker-Planck diffusion equation with sources from the low-energy plasma sheet population and losses to the atmosphere and magnetopause. We perform a coupled simulation of the Rice Convection Model (RCM) and Versatile Electron Radiation Belt (VERB) code. The RCM models magnetospheric convection and provides a low-energy electron seed population for the VERB diffusion code simulations of the Earth's radiation belts. VERB simulations are driven by the realistic time-dependent electron seed population and by the Kp index, which is used to specify rates of diffusion by ultralow frequency (ULF) and very low frequency wave activity and, therefore, diffusion processes. Radial diffusion is produced by ULF waves, while pitch angle and energy diffusion are produced by chorus waves outside the plasmasphere and by hiss waves inside the plasmasphere. The results of the simulation indicate that storm time enhanced magnetospheric convection combined with radial diffusion can bring electrons with tens of keV energy close to the Earth and can affect electron fluxes at 3–4 RE. These electrons can be further accelerated locally by chorus waves to MeV energies. Furthermore, outward radial diffusion smooths out the peak of the high-energy fluxes and produces MeV electron enhancement around geosynchronous orbit (6–7 RE) despite the absence of local electron acceleration in that region. Our coupled simulations indicate that local acceleration in the inner magnetosphere may be a dominant source of relativistic electrons that reach geosynchronous orbit.}
}