Journal article
Rapid Precipitation of Relativistic Electron by EMIC Rising‐Tone Emissions Observed by the Van Allen Probes
Journal of geophysical research. Space physics, Vol.124(8), pp.6701-6714
08/2019
DOI: 10.1029/2019JA026772
Abstract
On 23 February 2014, Van Allen Probes sensors observed quite strong electromagnetic ion cyclotron (EMIC) waves in the outer dayside magnetosphere. The maximum amplitude was more than 14 nT, comparable to 7% of the magnitude of the ambient magnetic field. The EMIC waves consisted of a series of coherent rising tone emissions. Rising tones are excited sporadically by energetic protons. At the same time, the probes detected drastic fluctuations in fluxes of MeV electrons. It was found that the electron fluxes decreased by more than 30% during the 1 min following the observation of each EMIC rising tone emissions. Furthermore, it is concluded that the flux reduction is a nonadiabatic (irreversible) process since holes in the particle flux levels appear as drift echoes with energy dispersion. We examine the process of electron pitch angle scattering by nonlinear wave trapping due to anomalous cyclotron resonance with EMIC rising tone emissions. The energy range of precipitated electrons agrees with the presumed energy for the threshold amplitude for nonlinear wave trapping. This is the first report of rapid precipitation (<1 min) of relativistic electrons by EMIC rising tone emissions and their drift echoes in time observed by spacecraft.
Key Points
Relativistic electrons disappear following intense EMIC rising tone in a few minutes
Drift echoes of localized electron depletion are detected
This is the direct observation of rapid loss process by the nonlinear EMIC scattering
Details
- Title: Subtitle
- Rapid Precipitation of Relativistic Electron by EMIC Rising‐Tone Emissions Observed by the Van Allen Probes
- Creators
- S. Nakamura - Kyoto UniversityY. Omura - Kyoto UniversityC. Kletzing - University of IowaD. N. Baker - Laboratory for Atmospheric and Space Physics
- Resource Type
- Journal article
- Publication Details
- Journal of geophysical research. Space physics, Vol.124(8), pp.6701-6714
- DOI
- 10.1029/2019JA026772
- ISSN
- 2169-9380
- eISSN
- 2169-9402
- Number of pages
- 14
- Grant note
- MEXT/JSPS (JP15H05815; JP17H06140)
- Language
- English
- Date published
- 08/2019
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984429027302771
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