Počet záznamů: 1  

Identification of the source of quasiperiodic VLF emissions using ground-based and Van Allen Probes satellite observations

  1. 1.
    0465194 - ÚFA 2017 ZA eng A - Abstrakt
    Demekhov, A. G. - Titova, E. E. - Kozelov, B. V. - Pasmanik, D. L. - Manninen, J. - Santolík, Ondřej - Kletzing, C. A. - Reeves, G.
    Identification of the source of quasiperiodic VLF emissions using ground-based and Van Allen Probes satellite observations.
    7th VERSIM-RBS: Abstracts. Hermanus: SANSA, 2016. s. 31.
    [VERSIM and RadBelt 2016 /7./. 19.09.2016-24.09.2016, Hermanus]
    Institucionální podpora: RVO:68378289
    Klíčová slova: plasmasphere * Van Allen Probe A * whistler mode waves * quasiperiodic VLF emissions
    Kód oboru RIV: BL - Fyzika plazmatu a výboje v plynech
    https://events.sansa.org.za/images/2016/VERSIM/abstracts/VERSIM_2016_abstracts.pdf

    We discuss quasiperiodic VLF emissions (in the frequency range 2 to 6 kHz) observed by
    Van Allen Probe A and a ground based site in Kannuslehto (Finland, L = 5.5) during a
    substorm of January 25, 2013. The spacecraft detected them in the night sector at L = 3.0
    to 4.2 when it was in the plasmasphere. Their quasi-period decreased from 6 to 3 min
    during the event. We find one-to-one correspondence between the quasiperiodic
    elements detected in space and on the ground, which indicates the temporal nature of
    the observed quasi-period variation.
    Multiсomponent measurements of the wave electric and magnetic fields by the Van Allen
    Probe A show that the quasiperiodic emissions were almost circularly right-hand
    polarized whistler mode waves and had predominantly small (below 30°) wave vector
    angles with respect to the magnetic field.
    In the probable source region of these signals (L about 4), we observed synchronous
    variations of electron distribution function at energies of 10–20 keV and the quasiperiodic
    elements. In the pause between the quasiperiodic elements pitch angle distribution of
    these electrons had a maximum near 90°, while they become more isotropic during the
    quasiperiodic elements. The growth rate of whistler mode waves calculated for the
    electron distribution functions measured by Van Allen Probe A corresponds well to the
    spectra of observed emissions.
    We propose to explain the quasiperiodic emissions by auto-oscillation regime of the
    cyclotron instability and simulate such regimes using the flow cyclotron maser model for
    the parameters close to measured ones.
    Trvalý link: http://hdl.handle.net/11104/0263854

     
     
Počet záznamů: 1  

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