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

E. E Titova; B. V Kozelov; A. G Demekhov; J Manninen; O Santolik; C. A Kletzing; G Reeves

doi:10.1002/2015GL064911

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

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

E. E Titova, B. V Kozelov, A. G Demekhov, J Manninen, O Santolik, C. A Kletzing and G Reeves

Geophysical research letters, Vol.42(15), pp.6137-6145

08/16/2015

DOI: 10.1002/2015GL064911

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Abstract

We report on simultaneous spacecraft and ground-based observations of quasiperiodic VLF emissions and related energetic-electron dynamics. Quasiperiodic emissions in the frequency range 2–6 kHz were observed during a substorm on 25 January 2013 by Van Allen Probe-A and a ground-based station in the Northern Finland. The spacecraft detected the VLF signals near the geomagnetic equator in the night sector at L = 3.0–4.2 when it was inside the plasmasphere. During the satellite motion toward higher latitudes, the time interval between quasiperiodic elements decreased from 6 min to 3 min. We find one-to-one correspondence between the quasiperiodic elements detected by Van Allen Probe-A and on the ground, which indicates the temporal nature of the observed variation in the time interval between quasiperiodic elements. 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 development of quasiperiodic elements. The parallel energies of the electrons for which the data suggest direct evidence of the wave-particle interactions is in a reasonable agreement with the estimated cyclotron resonance energy for the observed waves.

energetic electrons

quasiperiodic emissions

Van Allen Probes

VLF waves

Details

Title: Subtitle: Identification of the source of quasiperiodic VLF emissions using ground-based and Van Allen Probes satellite observations
Creators: E. E Titova - Polar Geophysical Institute
B. V Kozelov - Polar Geophysical Institute
A. G Demekhov - Polar Geophysical Institute
J Manninen - Sodankylä Geophysical Observatory Sodankylä Finland
O Santolik - Charles University
C. A Kletzing - University of Iowa
G Reeves - Los Alamos National Laboratory
Resource Type: Journal article
Publication Details: Geophysical research letters, Vol.42(15), pp.6137-6145
Publisher: Blackwell Publishing Ltd
DOI: 10.1002/2015GL064911
ISSN: 0094-8276
eISSN: 1944-8007
Number of pages: 9
Grant note: name: Sodankylä Geophysical Observatory; DOI: 10.13039/501100006769, name: Russian Science Foundation, award: 15-12-20005; name: Premium Academiae, award: P209-11-2280, LH14010; name: JHU/APL, award: 921647; name: NASA Prime, award: NAS5-01072
Language: English
Date published: 08/16/2015
Academic Unit: Physics and Astronomy
Record Identifier: 9984199931602771

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