Consequences of the Duration of Solar Energetic Particle-Associated Magnetic Storms on the Intensity of Geomagnetically Trapped Protons

  1. T. E. Moore,
  2. J. H. Waite Jr.,
  3. T. W. Moorehead and
  4. W. B. Hanson
  1. W. N. Spjeldvik

Published Online: 18 MAR 2013

DOI: 10.1029/GM044p0311

Modeling Magnetospheric Plasma

Modeling Magnetospheric Plasma

How to Cite

Spjeldvik, W. N. (1988) Consequences of the Duration of Solar Energetic Particle-Associated Magnetic Storms on the Intensity of Geomagnetically Trapped Protons, in Modeling Magnetospheric Plasma (eds T. E. Moore, J. H. Waite, T. W. Moorehead and W. B. Hanson), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM044p0311

Author Information

  1. Department of Physics, Weber State College, Ogden, Utah 84408

Publication History

  1. Published Online: 18 MAR 2013
  2. Published Print: 1 JAN 1988

ISBN Information

Print ISBN: 9780875900704

Online ISBN: 9781118664414



  • Space plasmas—Mathematical models;
  • Magnetosphere—Mathematical models;
  • Ionosphere—Mathematical models


The development of a time-dependent model for geomagnetically confined protons has proceeded to the stage where model calculations may be used to simulate and predict the time-variable proton radiation zone. The model has been used to study the diffusive injection of solar energetic protons into the stable trapping region during major magnetic storms. Although essentially all model parameters can be time variable, this paper analyzes the effects of time variations in the radial diffusion coefficient and in the outer zone boundary condition imposed at the approximate outer limit of the stable trapping region (L = 7) beyond which protons are unable to complete a drift trajectory around the world. First, the steady state equilibrium for radiation belt protons was simulated throughout the equatorial trapping region consistent with imposed quiet-time boundary conditions and the quiet-time average radial diffusion coefficient. Then, the fully time-dependent proton transport equation was solved in time, space, and energy equivalent for characteristic major magnetic storm and solar energetic proton events. In this paper, perturbation magnitudes have been kept fixed, but the duration of the events has been varied. It was found that for several tens of kiloelectron volt protons, short-lived events on time scales of hours have almost the same radiation belt consequences as more enduring events. In contrast, radiation belt protons in the mega-electron volt range are strongly dependent on the duration time scales of the arrival of energetic solar protons and on the maintenance of an enhanced radial diffusion coefficient.