University of Oulu

Demekhov, A. G., Titova, E. E., Manninen, J., Nikitenko, A. S., & Pilgaev, S. V. (2021). Short periodic VLF emissions observed simultaneously by Van Allen Probes and on the ground. Geophysical Research Letters, 48, e2021GL095476.

Short periodic VLF emissions observed simultaneously by Van Allen probes and on the ground

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Author: Demekhov, A. G.1,2; Titova, E. E.1,3; Manninen, J.4;
Organizations: 1Polar Geophysical Institute, Apatity, Russia
2Institute of Applied Physics of the Russian Academy of Sciences, Nizhny Novgorod, Russia
3Space Research Institute of the Russian Academy of Sciences, Moscow, Russia
4Sodankylä Geophysical Observatory, Sodankylä, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 3.6 MB)
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Language: English
Published: American Geophysical Union, 2021
Publish Date: 2022-04-10


We present simultaneous observations of very low-frequency emissions with periodic bursts by Van Allen Probe near geomagnetic equator and Kannuslehto and Lovozero ground-based sites. The repetition period and ground–spacecraft delay are consistent with guided whistler wave propagation between conjugate ionospheres. In contrast to lightning whistlers, the group velocity dispersion is not accumulated from one burst to another, thus implying a nonlinear mechanism of its compensation. Two regimes are observed. In one regime, Poynting flux direction alternates in the magnetosphere, and the burst period (2 s) is half of that detected on the ground (4 s), corresponding to single-wave packet bouncing along the field line. This regime is switched to the other one, with burst period unchanged in the magnetosphere but halved on the ground. In this second regime, no alternating Poynting flux direction is observed. The second regime corresponds to two symmetrically propagating wave packets synchronously meeting at the equator.

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Series: Geophysical research letters
ISSN: 0094-8276
ISSN-E: 1944-8007
ISSN-L: 0094-8276
Volume: 48
Issue: 20
Article number: e2021GL095476
DOI: 10.1029/2021GL095476
Type of Publication: A1 Journal article – refereed
Field of Science: 115 Astronomy and space science
Funding: The work of A. G. Demekhov, E. E. Titova, A. S. Nikitenko, and S. V. Pilgaev was partially supported by the State task AAAA–A18–118012490100–7 of Polar Geophysical Institute. The work with KAN data was supported by the Academy of Finland under grant 330783.
Academy of Finland Grant Number: 330783
Detailed Information: 330783 (Academy of Finland Funding decision)
Dataset Reference: Data Availability Statement : VAP-A data used in this paper can be found on the EMFISIS website ( KAN data are available at LOZ data are available at
Copyright information: © 2021. American Geophysical Union.