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Peculiar Nighttime Ionospheric Enhancements Over the Asian Sector During the May 2024 Superstorm.

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Title: Peculiar Nighttime Ionospheric Enhancements Over the Asian Sector During the May 2024 Superstorm.
Authors: Huang, Fuqing1,2,3 (AUTHOR), Lei, Jiuhou1 (AUTHOR) leijh@ustc.edu.cn, Zhang, Shun‐Rong4 (AUTHOR), Wang, Yihan1 (AUTHOR), Li, Zhongli1 (AUTHOR), Zhong, Jiahao5 (AUTHOR), Yan, Rui6 (AUTHOR), Aa, Ercha4,7 (AUTHOR), Zhima, Zeren6 (AUTHOR), Luan, Xiaoli1 (AUTHOR)
Source: Journal of Geophysical Research. Space Physics. Nov2024, Vol. 129 Issue 11, p1-14. 14p.
Subject Terms: *Magnetic storms, Equatorial ionization anomaly, Electric fields, Space environment, Electron density
Abstract: This study reports a peculiar nighttime ionospheric enhancement in the total electron content (TEC) from the geostationary (GEO) satellites in response to the geomagnetic superstorm of May 2024. The enhancements occurred at low to mid‐latitudes during the storm's recovery phase on 11–12 May, with the TEC values almost twice as high as the quiet ones. Surprisingly, the nighttime ionospheric enhancements sub‐rotated westward with a speed of ∼130.5 m/s. The nighttime TEC enhancements lasted ∼5–7 hr for a given location and persisted over half a day over wide longitude ranges. Meanwhile, ionosonde data from two equatorial ionization anomaly (EIA) stations showed a higher peak height of the F2 layer, and a significant double‐crest EIA structure was observed by both GEO TECs and in situ electron densities from China Seismo‐Electromagnetic Satellite during this period of interest, indicating a possible contribution from disturbance electric fields producing nighttime eastward equatorial electric fields. Nevertheless, it remains a mystery whether the nighttime TEC enhancement and its movement were associated with the wind disturbance dynamo. Plain Language Summary: Geomagnetic storms can greatly disturb the ionosphere, resulting in various abnormal ionospheric structures affecting the radio signal propagations of different frequencies. During the most intense storm of May 2024 in the past 20 years, we observed unusual nighttime ionospheric enhancements at low to mid‐latitudes. Unlike the fixed localized enhancements reported in previous studies, these enhancements were moving structures. They were observed in a wide longitudinal extension over the Pacific Ocean and Asia and persisted for more than half a day, even extending beyond sunrise, with a westward propagation speed of about 130.5 m/s. This paper presents a newly observed space weather event and highlights the less understood aspects of this phenomenon. Key Points: Abnormal nighttime ionospheric enhancements were observed by the GEO TECs during the May 2024 superstorm's recovery phaseThe nighttime ionospheric enhancements had movement structures with a westward velocity of ∼130.5 m/sWhether the disturbance electric field is the cause for the moved nighttime TEC enhancements remains a mystery to resolve [ABSTRACT FROM AUTHOR]
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Abstract:This study reports a peculiar nighttime ionospheric enhancement in the total electron content (TEC) from the geostationary (GEO) satellites in response to the geomagnetic superstorm of May 2024. The enhancements occurred at low to mid‐latitudes during the storm's recovery phase on 11–12 May, with the TEC values almost twice as high as the quiet ones. Surprisingly, the nighttime ionospheric enhancements sub‐rotated westward with a speed of ∼130.5 m/s. The nighttime TEC enhancements lasted ∼5–7 hr for a given location and persisted over half a day over wide longitude ranges. Meanwhile, ionosonde data from two equatorial ionization anomaly (EIA) stations showed a higher peak height of the F2 layer, and a significant double‐crest EIA structure was observed by both GEO TECs and in situ electron densities from China Seismo‐Electromagnetic Satellite during this period of interest, indicating a possible contribution from disturbance electric fields producing nighttime eastward equatorial electric fields. Nevertheless, it remains a mystery whether the nighttime TEC enhancement and its movement were associated with the wind disturbance dynamo. Plain Language Summary: Geomagnetic storms can greatly disturb the ionosphere, resulting in various abnormal ionospheric structures affecting the radio signal propagations of different frequencies. During the most intense storm of May 2024 in the past 20 years, we observed unusual nighttime ionospheric enhancements at low to mid‐latitudes. Unlike the fixed localized enhancements reported in previous studies, these enhancements were moving structures. They were observed in a wide longitudinal extension over the Pacific Ocean and Asia and persisted for more than half a day, even extending beyond sunrise, with a westward propagation speed of about 130.5 m/s. This paper presents a newly observed space weather event and highlights the less understood aspects of this phenomenon. Key Points: Abnormal nighttime ionospheric enhancements were observed by the GEO TECs during the May 2024 superstorm's recovery phaseThe nighttime ionospheric enhancements had movement structures with a westward velocity of ∼130.5 m/sWhether the disturbance electric field is the cause for the moved nighttime TEC enhancements remains a mystery to resolve [ABSTRACT FROM AUTHOR]
ISSN:21699380
DOI:10.1029/2024JA033350