Energetic Proton Spectra Measured by the Van Allen Probes

Summers, Danny; Shi, Run; Engebretson, M. J.; Oksavik, K.; Manweiler, J. W.; Mitchell, D. G.

doi:10.1002/2017ja024484

Cited by 12 publications

(13 citation statements)

References 45 publications

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“…The level 3‐PAP data with pitch angle information are adopted in this study. Due to the high‐voltage issues during the early phase of the emission of RBSPICE‐A, we only adopted the data from RBSPICE‐B in the present study (Summers et al., 2017). To ensure the reliability of the RBSPICE TOFxE product used in this study, we have replaced the data of the lowest energy channel from the TOFxE product with that of a similar energy channel from the TOFxPHHELT product (personal communications with Martina Gkioulidou).…”

Section: Instrumentation and Data Setsmentioning

confidence: 99%

Global Distribution of Reversed Energy Spectra of Ring Current Protons Based on Van Allen Probes Observations

et al. 2021

Geophysical Research Letters

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Energy spectra of ring current protons are crucial to understanding the ring current dynamics. Based on high‐quality Van Allen Probes RBSPICE measurements, we investigate the global distribution of the reversed proton energy spectra using the 2013–2019 RBSPICE data sets. The reversed proton energy spectra are characterized by the distinct flux minima around 50–100 keV and flux maxima around 200–400 keV. Our results show that the reversed proton energy spectrum is prevalent inside the plasmasphere, with the occurrence rates >90% at L ∼ 2–4 during geomagnetically quiet periods. Its occurrence also manifests a significant decrease trend with increasing L‐shell and enhanced geomagnetic activity. It is indicated that the substorm‐associated and/or convection processes are likely to lead to the disappearances of the reversed spectra. These results provide important clues for exploring the underlying physical mechanisms responsible for the formation and evolution of reversed proton energy spectra.

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Section: Instrumentation and Data Setsmentioning

confidence: 99%

Global Distribution of Reversed Energy Spectra of Ring Current Protons Based on Van Allen Probes Observations

et al. 2021

Geophysical Research Letters

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“…EMIC waves scatter~MeV electrons and~10s-100s keV protons into the loss cone via cyclotron resonance, potentially leading to losses of radiation belt electrons and ring current ions (Cao et al, 2016;Jordanova et al, 2008;Jordanova & Miyoshi, 2005;Li et al, 2007;Meredith et al, 2014;Summers et al, 2017; ©2019. American Geophysical Union.…”

Section: Introductionmentioning

confidence: 99%

Direct Observation of Subrelativistic Electron Precipitation Potentially Driven by EMIC Waves

Capannolo

et al. 2019

Geophysical Research Letters

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Electromagnetic ion cyclotron (EMIC) waves are known to typically cause electron losses into Earth's upper atmosphere at >~1 MeV, while the minimum energy of electrons subject to efficient EMIC‐driven precipitation loss is unresolved. This letter reports electron precipitation from subrelativistic energies of ~250 keV up to ~1 MeV observed by the Focused Investigations of Relativistic Electron Burst Intensity, Range and Dynamics (FIREBIRD‐II) CubeSats, while two Polar Operational Environmental Satellites (POES) observed proton precipitation nearby. Van Allen Probe A detected EMIC waves (~0.7–2.0 nT) over the similar L shell extent of electron precipitation observed by FIREBIRD‐II, albeit with a ~1.6 magnetic local time (MLT) difference. Although plasmaspheric hiss and magnetosonic waves were also observed, quasi‐linear calculations indicate that EMIC waves were the most efficient in driving the electron precipitation. Quasi‐linear theory predicts efficient precipitation at >0.8–1 MeV (due to H‐band EMIC waves), suggesting that other mechanisms are required to explain the observed subrelativistic electron precipitation.

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“…A recent study by Hirai et al () showed direct evidence of correlation between the rising tone EMIC wave structure and the associated bursts of REP. Pitch angle scattering of ring current protons (~10 s of keV) driven by EMIC waves has been often associated with proton aurora (Cao et al, ; Miyoshi et al, ; Summers et al, ; Xiao et al, ; Yuan et al, ).…”

Section: Introductionmentioning

confidence: 99%

Energetic Electron Precipitation: Multievent Analysis of Its Spatial Extent During EMIC Wave Activity

Capannolo

et al. 2019

JGR Space Physics

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Electromagnetic ion cyclotron (EMIC) waves can drive precipitation of tens of keV protons and relativistic electrons, and are a potential candidate for causing radiation belt flux dropouts. In this study, we quantitatively analyze three cases of EMIC-driven precipitation, which occurred near the dusk sector observed by multiple Low-Earth-Orbiting (LEO) Polar Operational Environmental Satellites/Meteorological Operational satellite programme (POES/MetOp) satellites. During EMIC wave activity, the proton precipitation occurred from few tens of keV up to hundreds of keV, while the electron precipitation was mainly at relativistic energies. We compare observations of electron precipitation with calculations using quasi-linear theory. For all cases, we consider the effects of other magnetospheric waves observed simultaneously with EMIC waves, namely, plasmaspheric hiss and magnetosonic waves, and find that the electron precipitation at MeV energies was predominantly caused by EMIC-driven pitch angle scattering. Interestingly, each precipitation event observed by a LEO satellite extended over a limited L shell region (ΔL~0.3 on average), suggesting that the pitch angle scattering caused by EMIC waves occurs only when favorable conditions are met, likely in a localized region. Furthermore, we take advantage of the LEO constellation to explore the occurrence of precipitation at different L shells and magnetic local time sectors, simultaneously with EMIC wave observations near the equator (detected by Van Allen Probes) or at the ground (measured by magnetometers). Our analysis shows that although EMIC waves drove precipitation only in a narrow ΔL, electron precipitation was triggered at various locations as identified by POES/MetOp over a rather broad region (up to~4.4 hr MLT and~1.4 L shells) with similar patterns between satellites.

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Energetic Proton Spectra Measured by the Van Allen Probes

Cited by 12 publications

References 45 publications

Global Distribution of Reversed Energy Spectra of Ring Current Protons Based on Van Allen Probes Observations

Global Distribution of Reversed Energy Spectra of Ring Current Protons Based on Van Allen Probes Observations

Direct Observation of Subrelativistic Electron Precipitation Potentially Driven by EMIC Waves

Energetic Electron Precipitation: Multievent Analysis of Its Spatial Extent During EMIC Wave Activity

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