Harriet George

Postdoctoral researcher


Curriculum vitae



Laboratory for Atmospheric and Space Physics

University of Colorado Boulder



Outer Radiation Belt Flux and Phase Space Density Response to Sheath Regions: Van Allen Probes and GPS Observations


Journal article


M. Kalliokoski, M. Henderson, S. Morley, E. Kilpua, A. Osmane, L. Olifer, D. Turner, Allison J. Jaynes, H. George, S. Hoilijoki, L. Turc, M. Palmroth
Journal of Geophysical Research: Space Physics, 2023

Semantic Scholar DOI
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APA   Click to copy
Kalliokoski, M., Henderson, M., Morley, S., Kilpua, E., Osmane, A., Olifer, L., … Palmroth, M. (2023). Outer Radiation Belt Flux and Phase Space Density Response to Sheath Regions: Van Allen Probes and GPS Observations. Journal of Geophysical Research: Space Physics.


Chicago/Turabian   Click to copy
Kalliokoski, M., M. Henderson, S. Morley, E. Kilpua, A. Osmane, L. Olifer, D. Turner, et al. “Outer Radiation Belt Flux and Phase Space Density Response to Sheath Regions: Van Allen Probes and GPS Observations.” Journal of Geophysical Research: Space Physics (2023).


MLA   Click to copy
Kalliokoski, M., et al. “Outer Radiation Belt Flux and Phase Space Density Response to Sheath Regions: Van Allen Probes and GPS Observations.” Journal of Geophysical Research: Space Physics, 2023.


BibTeX   Click to copy

@article{m2023a,
  title = {Outer Radiation Belt Flux and Phase Space Density Response to Sheath Regions: Van Allen Probes and GPS Observations},
  year = {2023},
  journal = {Journal of Geophysical Research: Space Physics},
  author = {Kalliokoski, M. and Henderson, M. and Morley, S. and Kilpua, E. and Osmane, A. and Olifer, L. and Turner, D. and Jaynes, Allison J. and George, H. and Hoilijoki, S. and Turc, L. and Palmroth, M.}
}

Abstract

Turbulent and compressed sheath regions preceding interplanetary coronal mass ejections strongly impact electron dynamics in the outer radiation belt. Changes in electron flux can occur on timescales of tens of minutes, which are unlikely to be captured by a two‐satellite mission. The recently released Global Positioning System (GPS) data set generally has shorter revisit times (at L ∼ 4–8) owing to the large number of satellites in the constellation equipped with energetic particle detectors. Investigating electron fluxes at energies from 140 keV to 4 MeV and sheaths observed in 2012–2018, we show that the flux response to sheaths on a timescale of 6 hr, previously reported from Van Allen Probes (RBSP) data, is reproduced by GPS measurements. Furthermore, GPS data enables derivation of the response on a timescale of 30 min, which further confirms that the energy and L‐shell dependent changes in electron flux are associated with the impact of the sheath. Sheath‐driven loss is underestimated over longer timescales as the electrons recover during the ejecta. We additionally show the response of electron phase space density (PSD), which is a key quantity in identifying non‐adiabatic loss from the system and electron energization through wave‐particle interactions. The PSD response is calculated from both RBSP and GPS data for the 6 hr timescale, as well as from GPS data for the 30 min timescale. The response is divided based on the geoeffectiveness of the sheaths revealing that electrons are effectively accelerated only during geoeffective sheaths, while loss commonly occurs during all sheaths.


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