University of Oulu

Gou, X., Li, L., Zhang, Y., Zhou, B., Feng, Y., Cheng, B., Raita, T., Liu, J., Zhima, Z., and Shen, X.: Ionospheric Pc1 waves during a storm recovery phase observed by the China Seismo-Electromagnetic Satellite, Ann. Geophys., 38, 775–787,, 2020.

Ionospheric Pc1 waves during a storm recovery phase observed by the China Seismo-Electromagnetic Satellite

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Author: Gou, Xiaochen1,2; Li, Lei1,2; Zhang, Yiteng1,2;
Organizations: 1State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing, China
2Joint Research and Development Center of the Chinese Science Academy and Shen County, Shandong, China
3Sodankylä Geophysical Observatory, University of Oulu, Sodankylä, Finland
4Institute of Crustal Dynamics, China Earthquake Administration, Beijing, China
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 3.2 MB)
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Language: English
Published: Copernicus Publications, 2020
Publish Date: 2020-09-10


During the storm recovery phase on 27 August 2018, the China Seismo-Electromagnetic Satellite (CSES) detected Pc1 wave activities in both the Northern Hemisphere and Southern Hemisphere in the high-latitude, post-midnight ionosphere with a central frequency of about 2 Hz. Meanwhile, the typical Pc1 waves were simultaneously observed for several hours by the Sodankylä Geophysical Observatory (SGO) stations on the ground. In this paper, we study the propagation characteristics and possible source regions of those waves. Firstly, we find that the Pc1 waves observed by the satellites exhibited mixed polarisation, and the wave normal is almost parallel with the background magnetic field. The field-aligned Poynting fluxes point downwards in both hemispheres, implying that the satellites are close to the wave injection regions in the ionosphere at about L=3. Furthermore, we also find that the estimated position of the plasmapause calculated by models is almost at L=3. Therefore, we suggest that the possible sources of waves are near the plasmapause, which is consistent with previous studies in that the outward expansion of the plasmasphere into the ring current during the recovery phase of geomagnetic storms may generate electromagnetic ion cyclotron (EMIC) waves, and these EMIC waves propagate northwards and southwards along the background magnetic field to the ionosphere at about L=3. Additionally, the ground station data show that Pc1 wave power attenuates with increasing distance from L=3, supporting the idea that the CSES observes the wave activities near the injection region. The observations are unique in that the Pc1 waves are observed in the ionosphere in nearly conjugate regions where transverse Alfvén waves propagate down into the ionosphere.

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Series: Annales geophysicae
ISSN: 0992-7689
ISSN-E: 1432-0576
ISSN-L: 0992-7689
Volume: 38
Issue: 3
Pages: 775 - 787
DOI: 10.5194/angeo-38-775-2020
Type of Publication: A1 Journal article – refereed
Field of Science: 115 Astronomy and space science
Funding: This work has been supported by the NSFC (grant no. 41904147) and the National Key Research and Development Programmes of the Ministry of Science and Technology of the People's Republic of China (MOST; grant nos. 2016YBF0501503 and 2018YFC1503501).
Copyright information: © Author(s) 2020. This work is distributed underthe Creative Commons Attribution 4.0 License.