Journal article
Van Allen Probes observation of a 360° phase shift in the flux modulation of injected electrons by ULF waves
Geophysical research letters, Vol.44(4), pp.1614-1624
02/28/2017
DOI: 10.1002/2016GL071252
Abstract
We present Van Allen Probe observation of drift‐resonance interaction between energetic electrons and ultralow frequency (ULF) waves on 29 October 2013. Oscillations in electron flux were observed at the period of ∼450 s, which is also the dominant period of the observed ULF magnetic pulsations. The phase shift of the electron fluxes (∼50 to 150 keV) across the estimated resonant energy (∼104 keV) is ∼360°. This phase relationship is different from the characteristic 180° phase shift as expected from the drift‐resonance theory. We speculate that the additional 180° phase difference arises from the inversion of electron phase space density (PSD) gradient, which in turn is caused by the drift motion of the substorm injected electrons. This PSD gradient adjusts the characteristic particle signatures in the drift‐resonance theory, which indicates a coupling effect between the magnetotail and the radiation belt and helps to better understand the wave‐particle interaction in the magnetosphere.
Key Points
Both electron flux oscillations in response to ULF waves and drift echoes of injected electrons are observed
A 360° phase shift in the electron fluxes modulated by ULF waves via drift‐resonance interaction is observed for the first time
The unusual phase relationship is associated with the inversion of PSD gradient caused by the drift motion of the injected electrons
Details
- Title: Subtitle
- Van Allen Probes observation of a 360° phase shift in the flux modulation of injected electrons by ULF waves
- Creators
- X.‐R Chen - Peking UniversityQ.‐G Zong - Peking UniversityX.‐Z Zhou - Peking UniversityJ. Bernard Blake - The Aerospace CorporationJ. R Wygant - University of MinnesotaC. A Kletzing - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Geophysical research letters, Vol.44(4), pp.1614-1624
- DOI
- 10.1002/2016GL071252
- ISSN
- 0094-8276
- eISSN
- 1944-8007
- Number of pages
- 11
- Grant note
- Major Project of Chinese National Programs for Fundamental Research and Development (2012CB825603) National Natural Science Foundation of China (4162780006)
- Language
- English
- Date published
- 02/28/2017
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984199683002771
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