Generation Process of Large‐Amplitude Upper‐Band Chorus Emissions Observed by Van Allen Probes

Yuko Kubota; Yoshiharu Omura; Craig Kletzing; Geoffrey Reeves

doi:10.1029/2017JA024782

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Generation Process of Large‐Amplitude Upper‐Band Chorus Emissions Observed by Van Allen Probes

Journal article

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Generation Process of Large‐Amplitude Upper‐Band Chorus Emissions Observed by Van Allen Probes

Yuko Kubota, Yoshiharu Omura, Craig Kletzing and Geoffrey Reeves

Journal of geophysical research. Space physics, Vol.123(5), pp.3704-3713

05/2018

DOI: 10.1029/2017JA024782

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Abstract

We analyze large‐amplitude upper‐band chorus emissions measured near the magnetic equator by the Electric and Magnetic Field Instrument Suite and Integrated Science instrument package on board the Van Allen Probes. In setting up the parameters of source electrons exciting the emissions based on theoretical analyses and observational results measured by the Helium Oxygen Proton Electron instrument, we calculate threshold and optimum amplitudes with the nonlinear wave growth theory. We find that the optimum amplitude is larger than the threshold amplitude obtained in the frequency range of the chorus emissions and that the wave amplitudes grow between the threshold and optimum amplitudes. In the frame of the wave growth process, the nonlinear growth rates are much greater than the linear growth rates. Key Points Observations by Van Allen Probes show that the upper‐band chorus emissions exist both inside and outside the plasmasphere The densities and thermal velocities of electrons generating the chorus emissions are evaluated from HOPE particle data Observed chorus amplitude and frequency ranges agree with the nonlinear wave growth theory

chorus

energetic electrons

nonlinear wave‐particle interaction

observation

radiation belt

Van Allen Probes

Details

Title: Subtitle: Generation Process of Large‐Amplitude Upper‐Band Chorus Emissions Observed by Van Allen Probes
Creators: Yuko Kubota - Kyoto University
Yoshiharu Omura - Kyoto University
Craig Kletzing - University of Iowa
Geoffrey Reeves - Los Alamos National Laboratory
Resource Type: Journal article
Publication Details: Journal of geophysical research. Space physics, Vol.123(5), pp.3704-3713
DOI: 10.1029/2017JA024782
ISSN: 2169-9380
eISSN: 2169-9402
Number of pages: 10
Grant note: NASA (NAS5-01072) MEXT/JSPS KAKENHI (16J11490; 17H06140)
Language: English
Date published: 05/2018
Academic Unit: Physics and Astronomy
Record Identifier: 9984199661902771

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