Relativistic electron dynamics produced by azimuthally localized poloidal mode ULF waves: Boomerang-shaped pitch angle evolutions

TitleRelativistic electron dynamics produced by azimuthally localized poloidal mode ULF waves: Boomerang-shaped pitch angle evolutions
Publication TypeJournal Article
Year of Publication2017
AuthorsHao, YX, Zong, Q-G, Zhou, X-Z, Rankin, R, Chen, XR, Liu, Y, Fu, SY, Spence, HE, Blake, JB, Reeves, GD
JournalGeophysical Research Letters
Date Published07/2017
Keywordsdrift resonance; interplanetary shock; localized waves; Radiation belts; ULF waves; Van Allen Probes; wave-particle interaction
AbstractWe present an analysis of “boomerang-shaped” pitch angle evolutions of outer radiation belt relativistic electrons observed by the Van Allen Probes after the passage of an interplanetary shock on June 7th, 2014. The flux at different pitch angles is modulated by Pc5 waves, with equatorially mirroring electrons reaching the satellite first. For 90∘ pitch angle electrons, the phase change of the flux modulations across energy exceeds 180∘, and increasingly tilts with time. Using estimates of the arrival time of particles of different pitch angles at the spacecraft location, a scenario is investigated in which shock-induced ULF waves interact with electrons through the drift resonance mechanism in a localized region westward of the spacecraft. Numerical calculations on particle energy gain with the modified ULF wave field reproduce the observed boomerang stripes and modulations in the electron energy spectrogram. The study of boomerang stripes and their relationship to drift-resonance taking place at a location different from the observation point adds new understanding of the processes controlling the dynamics of the outer radiation belt.
URLhttp://onlinelibrary.wiley.com/doi/10.1002/2017GL074006/full
DOI10.1002/2017GL074006
Short TitleGeophys. Res. Lett.


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