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Filters: Keyword is drift‐bounce resonance  [Clear All Filters]
2019
Authors: Ren Jie, Zong Q. G., Zhou X. Z., Spence H E, Funsten H O, et al.
Title: Cold Plasmaspheric Electrons Affected by ULF Waves in the Inner Magnetosphere: A Van Allen Probes Statistical Study
Abstract: Six years of Van Allen Probes data are used to investigate cold plasmaspheric electrons affected by ultralow‐frequency (ULF) waves in the inner magnetosphere (L<7) including spatial distributions, occurrence conditions, and resonant energy range. Events exhibit a global distribution within L= 4–7 but preferentially occur at L∼5.5–7 in the dayside, while there is higher occurrence rate in the duskside than dawnside. They can occur under different geomagnetic activities and solar wind velocities (VS), but the occurrence rates are increasing with larger AE, |SYMH|, and VS. These features are closely associated with the generation and propagation of ULF waves in Pc4 (45–150 s) and Pc5 (150–600 s) bands. Combined with electron observations from HOPE instrument, the resonant energies. . .
Date: 10/2019 Publisher: Journal of Geophysical Research: Space Physics Pages: 7954 - 7965 DOI: 10.1029/2019JA027009 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA027009
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Authors: Yamamoto K., Nosé M., Keika K, Hartley D.P., Smith C.W., et al.
Title: Eastward Propagating Second Harmonic Poloidal Waves Triggered by Temporary Outward Gradient of Proton Phase Space Density: Van Allen Probe A Observation
Abstract: Two wave packets of second harmonic poloidal Pc 4 waves with a wave frequency of ~7 mHz were detected by Van Allen Probe A at a radial distance of ~5.8 RE and magnetic local time of 13 hr near the magnetic equator, where plasmaspheric refilling was in progress. Proton butterfly distributions with energy dispersions were also measured at the same time; the proton fluxes at 10‐30 keV oscillated with the same frequency as the Pc 4 waves. Using the ion sounding technique, we find that the Pc 4 waves propagated eastward with an azimuthal wave number (m number) of ~220 and ~260 for each wave packet, respectively. Such eastward propagating high‐m (m > 100) waves were seldom reported in previous studies. The condition of drift‐bounce resonance is well satisfied for the estimated m numbers in. . .
Date: 11/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2019JA027158 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA027158
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2018
Authors: Chaston C. C., Bonnell J. W., Halford A J, Reeves G D, Baker D N, et al.
Title: Pitch Angle Scattering and Loss of Radiation Belt Electrons in Broadband Electromagnetic Waves
Abstract: A magnetic conjunction between Van Allen Probes spacecraft and the Balloon Array for Radiation‐belt Relativistic Electron Losses (BARREL) reveals the simultaneous occurrence of broadband Alfvénic fluctuations and multi‐timescale modulation of enhanced atmospheric X‐ray bremsstrahlung emission. The properties of the Alfvénic fluctuations are used to build a model for pitch angle scattering in the outer radiation belt on electron gyro‐radii scale field structures. It is shown that this scattering may lead to the transport of electrons into the loss cone over an energy range from hundreds of keV to multi‐MeV on diffusive timescales on the order of hours. This process may account for modulation of atmospheric X‐ray fluxes observed from balloons and constitute a significant loss p. . .
Date: 09/2018 Publisher: Geophysical Research Letters DOI: 10.1029/2018GL079527 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL079527
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