Generation of extremely low frequency chorus in Van Allen radiation belts. Issue 3 (15th March 2017)

• Record Type: Journal Article
• Authors: Xiao, Fuliang; Liu, Si; Tao, Xin; Su, Zhenpeng; Zhou, Qinghua; Yang, Chang; He, Zhaoguo; He, Yihua; Gao, Zhonglei; Baker, D. N.; Spence, H. E.; Reeves, G. D.; Funsten, H. O.; Blake, J. B.
• Is Part Of: Journal of geophysical research. Volume 122:Issue 3(2017)
• Page Start: 3201
• Page End: 3211
• Publication Date: 2017-03-15
• Subjects: ELF chorus waves -- wave‐particle interaction -- relativistic distribution -- RBSP results; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/2016JA023561
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: Recent studies have shown that chorus can efficiently accelerate the outer radiation belt electrons to relativistic energies. Chorus, previously often observed above 0.1 equatorial electron gyrofrequency f ce, was generated by energetic electrons originating from Earth's plasma sheet. Chorus below 0.1 f ce has seldom been reported until the recent data from Van Allen Probes, but its origin has not been revealed so far. Because electron resonant energy can approach the relativistic level at extremely low frequency, relativistic effects should be considered in the formula for whistler mode wave growth rate. Here we report high‐resolution observations during the 14 October 2014 small storm and firstly demonstrate, using a fully relativistic simulation, that electrons with the high‐energy tail population and relativistic pitch angle anisotropy can provide free energy sufficient for generating chorus below 0.1 f ce . The simulated wave growth displays a very similar pattern to the observations. The current results can be applied to Jupiter, Saturn, and other magnetized planets. Key Points: Initial RBSP correlated data of ELF chorus waves and energetic electron fluxes A fully relativistic treatment is adopted to examine how ELF chorus is generated ELF chorus can be generated by the high‐energy tail and relativistic anisotropy