University of Oulu

Liu, J., Shiokawa, K., Oyama, S.-I., Otsuka, Y., Jun, C.-W., Nosé, M., et al. (2023). A statistical study of longitudinal extent of Pc1 pulsations using seven PWING ground stations at subauroral latitudes. Journal of Geophysical Research: Space Physics, 128, e2021JA029987.

A statistical study of longitudinal extent of Pc1 pulsations using seven PWING ground stations at subauroral latitudes

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Author: Liu, Jie1; Shiokawa, Kazuo1; Oyama, Shin-Ichiro1,2,3;
Organizations: 1Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan
2National Institute of Polar Research, Tokyo, Japan
3Space Physics and Astronomy Research Unit, University of Oulu, Oulu, Finland
4National Institute of Information and Communications Technology, Koganei, Japan
5Polar Environment Data Science Center, Joint Support-Center for Data Science Research, Research Organization of Information and Systems, Tokyo, Japan
6The Graduate University for Advanced Studies, Kanagawa, Japan
7Kanazawa University, Kanazawa, Japan
8Athabasca University, Edmonton, AB, Canada
9Yakut Scientific Centre of Siberian Branch of the Russian Academy of Sciences, Yu.G.Shafer Institute of Cosmophysical Research and Aeronomy of Siberian Branch of the Russian Academy of Sciences, Yakutsk, Russia
10Institute of Solar-Terrestrial Physics, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia
11Sodankyla Geophysical Observatory, University of Oulu, Oulu, Finland
Format: article
Version: published version
Access: embargoed
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Language: English
Published: American Geophysical Union, 2023
Publish Date: 2023-07-09


Pc1 geomagnetic pulsations correspond to electromagnetic ion cyclotron (EMIC) waves in the magnetosphere and are excited there with frequencies of 0.2–5 Hz. The instantaneous longitudinal extent of Pc1 waves on the ground has not been estimated yet. In this study, we analyze the Pc1 pulsations observed at seven longitudinally-distributed ground stations at subauroral latitudes at ∼60° magnetic latitude for 1 year from July 2018 to June 2019. The hourly occurrence rates of Pc1 pulsations at all 7 stations have a peak (14%–39.6%) in the post-noon sector and a local minimum (4.1%–8.1%) at midnight. The average frequencies become highest (0.6–1.1 Hz) after midnight and lowest (0.3–0.5 Hz) after noon at all 7 stations. An increasing tendency of total Pc1 occurrence with respect to magnetic latitude was observed. Based on these observations, we obtained a peak of probability distribution of the instantaneous Pc1 longitudinal extent as ∼82.5° with a half maximum at ∼114°, though this probability distribution can be affected by the limitation of the number of the stations. We also made model calculations on the possible longitudinal extent using artificial random Pc1 waves with fixed extents. The comparison of the model results with the observation suggests longitudinal extent of 70°–86° comparable to the peak of probability distribution (∼82.5°). A superposed epoch analysis shows that the longitudinal extent of Pc1 waves tends to increase during recovery phase of geomagnetic storms.

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Series: Journal of geophysical research. Space physics
ISSN: 2169-9380
ISSN-E: 2169-9402
ISSN-L: 2169-9380
Volume: 128
Issue: 1
Article number: e2021JA029987
DOI: 10.1029/2021JA029987
Type of Publication: A1 Journal article – refereed
Field of Science: 115 Astronomy and space science
Funding: This article is based on the PWING project and other grants supported by the Japan Society for the Promotion of Science (JP 15H05747, 16H06286, 21H04518, JPJSBP120194814, JPJSBP120214805, JPJSCCB20210003) and is partially funded by Russian Foundation for Basic Research (21-55-50013; D. B.). Observations at Athabasca are in facilities sponsored by the Canada Foundation for Innovation and at Zhigansk supported by the Ministry of Science and Higher Education of the Russian Federation and the Siberian Branch of the Russian Academy of Sciences (registration number 122011700182-1).
Copyright information: © 2023. American Geophysical Union. All Rights Reserved.