University of Oulu

C., Martinez‐Calderon, Katoh, Y., Manninen, J., Kasahara, Y., Matsuda, S., Kumamoto, A., et al. ( 2020). Conjugate observations of dayside and nightside VLF chorus and QP emissions between Arase (ERG) and Kannuslehto, Finland. Journal of Geophysical Research: Physics, 125, e2019JA026663.

Conjugate observations of dayside and nightside VLF chorus and QP emissions between Arase (ERG) and Kannuslehto, Finland

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Author: Martinez‐Calderon, Claudia1,2; Katoh, Yuto1; Manninen, Jyrki2;
Organizations: 1Department of Geophysics, Graduate School of Science, Tohoku University, Sendai, Japan
2Institute for Space‐Earth Environmental Research, Nagoya University, Nagoya, Japan
3Sodankyla Geophysical Observatory, University of Oulu, Sodankyla, Finland
4Division of Electrical Engineering and Computer Science, Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Japan
5Institute of Space and Astronautical Science, JAXA, Tokyo, Japan
6Kyushu Institute of Technology, Graduate School of Engineering, Kitakyushu, Japan
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 33 MB)
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Language: English
Published: American Geophysical Union, 2020
Publish Date: 2020-07-09


We compare for the first time two conjugate events showing simultaneous very low frequency (VLF) wave observations between the same ground station and spacecraft, at different geomagnetic conditions and on opposite sides of the magnetosphere. Waves were observed at Kannuslehto (MLAT = 64.4°N, L=5.46), Finland, and on board Arase (Exploration of energization and Radiation in Geospace, ERG) in the inner magnetosphere. Case 1 on 28 March 2017 shows quasiperiodic (QP) emissions and chorus simultaneously observed on the postmidnight side during the recovery phase of a storm, with sustained high solar wind speed and AE index. Case 2 on 30 November 2017 shows clear one‐to‐one correspondence of QP elements on the noonside during geomagnetic quiet time (Dst>10 nT and AE<100 nT). We present the characteristics of both cases, focusing on coherence and spatial extent of the waves, electron density, and magnetic field variations. We report that the magnetic field gradient plays a role in the changes of spectral features of the waves.

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Series: Journal of geophysical research. Space physics
ISSN: 2169-9380
ISSN-E: 2169-9402
ISSN-L: 2169-9380
Volume: 125
Issue: 1
Article number: e2019JA026663
DOI: 10.1029/2019JA026663
Type of Publication: A1 Journal article – refereed
Field of Science: 115 Astronomy and space science
Funding: This work was supported by Grant‐in‐Aid for Scientific Research (17F17030) of the Japan Society for the Promotion of Science and by the JSPS International Research Fellowship. Y. K., S. M., Y. M., and K. S. are also supported by Grants‐in‐Aid for Scientific Research (18H03727, 15H05815, 15H05747, 16H06286, 16H06286, 14J02108, and 17K05668) and JSPS Bilateral Open Partnership Joint Research Projects.
Copyright information: © 2019. American Geophysical Union. All Rights Reserved.