EGU25-19871, updated on 11 Jul 2025
https://doi.org/10.5194/egusphere-egu25-19871
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
A Statistical Study of VLF Measurements during Geomagnetic Storms
wen Cheng, wei Xu, Xudong Gu, Binbin Ni, Shiwei Wang, Jingyuan Feng, Wenchen Ma, Hanqin Shi, Haotian Xu, Dongfang Zhai, and Yudi Pan
wen Cheng et al.
  • School of Earth and Space Science and Technology, Wuhan University, Wuhan, Hubei, China (1825587676@qq.com)

During geomagnetic storm, large fluxes of energetic particles can precipitate into the Earth’s atmosphere and causes excess ionization therein [Ni et al., GRL, 35, 11, 2008], ultimately leading to the depletion of polar ozone layer. The subionospheric Very Low Frequency (VLF, 3-30 kHz) technique has been widely utilized to study those space weather events that influence the D-region ionosphere, including electron precipitation from the radiation belts [Inan, GRL, 17, 6, 1990; Rodger, RG, 37, 317, 1999; Clilverd et al, RS, 36, 773, 2001]. However, most studies were devoted to the analysis of VLF measurements during one or several geomagnetic storms. Few statistical studies have been conducted and how VLF signals respond to geomagnetic storms, especially near the South Atlantic Anomaly (SAA) region, is insufficiently investigated.

In this study, we use the VLF data collected by the receiver developed by Wuhan University, and installed at the Great Wall Station (GWS) in Antarctica. We mainly focus on the measurements of VLF signals from the NAA, NPM, NML, and NLK transmitters, and a total of 18 moderate and strong geomagnetic storms between 2022 and 2023 have been investigated. The path from NAA to GWS is particularly noteworthy since it crosses the SAA region. Our results show that the disturbance caused by geomagnetic storms mainly occurred at sunset or during nighttime conditions, with an amplitude change of 5.3 dB during nighttime conditions and 6.1 dB during sunset. The disturbance typically ~last for 1.5 hours, and the maximum change of VLF amplitude typically occurred several hours after the minimum value of Dst index, with an average delay of 5 hours. The disturbance last for 1.5 hours and was not well correlated with the Dst index. The disturbances are likely caused by energetic particles within the drift loss cone angle that precipitate into the SAA region.

How to cite: Cheng, W., Xu, W., Gu, X., Ni, B., Wang, S., Feng, J., Ma, W., Shi, H., Xu, H., Zhai, D., and Pan, Y.: A Statistical Study of VLF Measurements during Geomagnetic Storms, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19871, https://doi.org/10.5194/egusphere-egu25-19871, 2025.