A Long-Lived Relativistic Electron Storage Ring Embedded in Earth’s Outer Van Allen Belt

Baker, D. N.; Kanekal, S.; Hoxie, V. C.; Henderson, M. G.; Li, X.; Spence, Harlan E.; Elkington, S. R.; Friedel, R. H.; Goldstein, J.; Hudson, M. K.; Reeves, G. D.; Thorne, R. M.; Kletzing, C. A.; Claudepierre, S. G.

doi:10.1126/science.1233518

Cited by 232 publications

(257 citation statements)

References 26 publications

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“…That study points out that, in this configuration, energetic and relativistic electrons will resonate with hiss waves near the equator and will be lost to the atmosphere on a time scale of a few days. However, highly relativistic electrons will be out of resonance with hiss waves near the equator, providing the reason why the unusual storage ring of highly relativistic electrons reported by Baker et al [2013] can persist for over four weeks.…”

Section: Discussionmentioning

confidence: 99%

Prompt energization of relativistic and highly relativistic electrons during a substorm interval: Van Allen Probes observations

Foster

Erickson

Baker

et al. 2014

Geophysical Research Letters

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On 17 March 2013, a large magnetic storm significantly depleted the multi-MeV radiation belt. We present multi-instrument observations from the Van Allen Probes spacecraft Radiation Belt Storm Probe A and Radiation Belt Storm Probe B at~6 Re in the midnight sector magnetosphere and from ground-based ionospheric sensors during a substorm dipolarization followed by rapid reenergization of multi-MeV electrons. A 50% increase in magnetic field magnitude occurred simultaneously with dramatic increases in 100 keV electron fluxes and a 100 times increase in VLF wave intensity. The 100 keV electrons and intense VLF waves provide a seed population and energy source for subsequent radiation belt enhancements. Highly relativistic (>2 MeV) electron fluxes increased immediately at L*~4.5 and 4.5 MeV flux increased >90 times at L* = 4 over 5 h. Although plasmasphere expansion brings the enhanced radiation belt multi-MeV fluxes inside the plasmasphere several hours postsubstorm, we localize their prompt reenergization during the event to regions outside the plasmasphere.

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Section: Discussionmentioning

confidence: 99%

Prompt energization of relativistic and highly relativistic electrons during a substorm interval: Van Allen Probes observations

Foster

Erickson

Baker

et al. 2014

Geophysical Research Letters

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120

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“…The double-dip (in D st ) storm on 8 October 2012 followed month-long observations of a three-belt structure of highenergy (MeV) electrons reported by Baker et al (2013). The event preceded sudden energization of the relativistic electrons on 9 October .…”

Section: October 2012mentioning

confidence: 99%

Magnetohydrodynamic modeling of three Van Allen Probes storms in 2012 and 2013

et al. 2015

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Abstract. Coronal mass ejection (CME)-shock compression of the dayside magnetopause has been observed to cause both prompt enhancement of radiation belt electron flux due to inward radial transport of electrons conserving their first adiabatic invariant and prompt losses which at times entirely eliminate the outer zone. Recent numerical studies suggest that enhanced ultra-low frequency (ULF) wave activity is necessary to explain electron losses deeper inside the magnetosphere than magnetopause incursion following CME-shock arrival. A combination of radial transport and magnetopause shadowing can account for losses observed at radial distances into L = 4.5, well within the computed magnetopause location. We compare ULF wave power from the Electric Field and Waves (EFW) electric field instrument on the Van Allen Probes for the 8 October 2013 storm with ULF wave power simulated using the Lyon-FedderMobarry (LFM) global magnetohydrodynamic (MHD) magnetospheric simulation code coupled to the Rice Convection Model (RCM). Two other storms with strong magnetopause compression, 8-9 October 2012 and 17-18 March 2013, are also examined. We show that the global MHD model captures the azimuthal magnetosonic impulse propagation speed and amplitude observed by the Van Allen Probes which is responsible for prompt acceleration at MeV energies reported for the 8 October 2013 storm. The simulation also captures the ULF wave power in the azimuthal component of the electric field, responsible for acceleration and radial transport of electrons, at frequencies comparable to the electron drift period. This electric field impulse has been shown to explain observations in related studies (Foster et al., 2015) of electron acceleration and drift phase bunching by the Energetic Particle, Composition, and Thermal Plasma Suite (ECT) instrument on the Van Allen Probes.

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“…We investigated a dropout event that occurred on 30 September to 1 October 2012, which we chose because of the drastic effect it had on the outer belt, including the eradication of the double outer belt structure identified by Baker et al [2013] and the unprecedented level of observational coverage provided by NASA's new Van Allen Probes (formerly Radiation Belt Storm Probes, RBSP) [Mauk et al, 2012] and THEMIS [Angelopoulos, 2008] missions combined with NOAA's GOES spacecraft at geosynchronous orbit (GEO). With such extensive multipoint coverage, this event allowed us to examine the timescales and full extent of the dropout for different particle energies, equatorial pitch angles, L*, and species, which we present here.…”

Section: Introductionmentioning

confidence: 99%

On the cause and extent of outer radiation belt losses during the 30 September 2012 dropout event

et al. 2014

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On 30 September 2012, a flux "dropout" occurred throughout Earth's outer electron radiation belt during the main phase of a strong geomagnetic storm. Using eight spacecraft from NASA's Time History of Events and Macroscale Interactions during Substorms (THEMIS) and Van Allen Probes missions and NOAA's Geostationary Operational Environmental Satellites constellation, we examined the full extent and timescales of the dropout based on particle energy, equatorial pitch angle, radial distance, and species. We calculated phase space densities of relativistic electrons, in adiabatic invariant coordinates, which revealed that loss processes during the dropout were > 90% effective throughout the majority of the outer belt and the plasmapause played a key role in limiting the spatial extent of the dropout. THEMIS and the Van Allen Probes observed telltale signatures of loss due to magnetopause shadowing and subsequent outward radial transport, including similar loss of energetic ring current ions. However, Van Allen Probes observations suggest that another loss process played a role for multi-MeV electrons at lower L shells (L* <~4).

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A Long-Lived Relativistic Electron Storage Ring Embedded in Earth’s Outer Van Allen Belt

Cited by 232 publications

References 26 publications

Prompt energization of relativistic and highly relativistic electrons during a substorm interval: Van Allen Probes observations

Prompt energization of relativistic and highly relativistic electrons during a substorm interval: Van Allen Probes observations

Magnetohydrodynamic modeling of three Van Allen Probes storms in 2012 and 2013

On the cause and extent of outer radiation belt losses during the 30 September 2012 dropout event

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