Direct Observation of Subrelativistic Electron Precipitation Potentially Driven by EMIC Waves
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Abstract |
Electromagnetic ion cyclotron (EMIC) waves are known to typically cause electron losses into Earth\textquoterights 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\textendash2.0 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\textendash1 MeV (due to H-band EMIC waves), suggesting that other mechanisms are required to explain the observed subrelativistic electron precipitation.
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Year of Publication |
2019
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Journal |
Geophysical Research Letters
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Date Published |
11/2019
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ISSN Number |
0094-8276
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URL |
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL084202
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DOI |
10.1029/2019GL084202
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