Ionospheric Pc1 waves during a storm recovery phase observed by CSES
During the storm recovery phase on August 27, 2018, the China Seismo-Electromagnetic Satellite (CSES) detected Pc1 wave activities both in the Northern and Southern hemispheres in the high latitude post-midnight ionosphere with a central frequency about 2 Hz. Meanwhile, the typical Pc1 waves were si...
| Main Authors: | , , , , , , , , |
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| Format: | Text |
| Language: | English |
| Published: |
2020
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| Subjects: | |
| Online Access: | https://doi.org/10.5194/angeo-2020-10 https://www.ann-geophys-discuss.net/angeo-2020-10/ |
| Summary: | During the storm recovery phase on August 27, 2018, the China Seismo-Electromagnetic Satellite (CSES) detected Pc1 wave activities both in the Northern and Southern hemispheres in the high latitude post-midnight ionosphere with a central frequency about 2 Hz. Meanwhile, the typical Pc1 waves were simultaneously observed by the Sodankylä Geophysical Observatory (SGO) stations on the ground for several hours. In this paper, we study the propagation characteristics and possible source regions of those waves. Firstly, we find that the satellites observed Pc1 waves exhibit mixed polarization and the wave normal is almost parallel with the background magnetic field. The field-aligned Poynting fluxes point downward in both hemispheres, implying 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 the possible sources of waves are near the plasmapause, which is consistent with previous studies 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 then these EMIC waves propagate along the background magnetic field northward and southward 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 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 transvers Alfven waves propagate down into the ionosphere. |
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