A model for falling-tone chorus

A. R. Soto-Chavez, G. Wang, A. Bhattacharjee, G. Y. Fu, H. M. Smith

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Motivated by the fact that geomagnetic field inhomogeneity is weak close to the chorus generation region and the observational evidence that falling-tone chorus tend to have large oblique angles of propagation, we propose that falling-tone chorus start as a marginally unstable mode. The marginally unstable mode requires the presence of a relatively large damping, which has its origins in the Landau damping of oblique waves in this collisionless environment. A marginally unstable mode produces phase-space structures that release energy and produce wave chirping. We show that the present model produces results in reasonable agreement with observations.

Original languageEnglish (US)
Pages (from-to)1838-1845
Number of pages8
JournalGeophysical Research Letters
Issue number6
StatePublished - Mar 28 2014

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Earth and Planetary Sciences(all)


  • Van Allen radiation belts
  • chorus
  • frequency sweep
  • wave-particle resonances
  • whistlers

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    Soto-Chavez, A. R., Wang, G., Bhattacharjee, A., Fu, G. Y., & Smith, H. M. (2014). A model for falling-tone chorus. Geophysical Research Letters, 41(6), 1838-1845. https://doi.org/10.1002/2014GL059320