Solar Energetic Proton Access to the Near-Equatorial Inner Magnetosphere

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Abstract
In this study we examine the ability of protons of solar origin to access the near-equatorial inner magnetosphere. Here we examine four distinct solar proton events from 20–200 MeV, concurrent with both quiet time and storm time conditions using proton data from the ACE satellite in the solar wind upstream of Earth and data from the Relativistic Electron Proton Telescope (REPT) instrument aboard Van Allen Probes. We examine the direct flux correspondence between interplanetary space and the inner magnetosphere. Small substructures in interplanetary space are observable in the REPT flux profiles, which can penetrate down to L values of ≤4. Furthermore, there are orbit-to-orbit variations in the west-to-east anisotropic flux ratios. The anisotropic flux ratios are used as a proxy for cutoff energies and display cutoff variations with L shell and energy. The dependence of the anisotropic flux ratio on Dst values is shown. The results paint a picture of highly dynamic spatial and temporal proton cutoff rigidities in the near-equatorial inner magnetosphere.
Notes
Year of Publication
2020
Journal
Journal of Geophysical Research: Space Physics
Volume
125
Number
Number of Pages
e2019JA027584
Date Published
05/2020
URL
https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019JA027584
DOI
https://doi.org/10.1029/2019JA027584