Ukrainian Antarctic Journal

Vol 24 No 1(32) (2026): Ukrainian Antarctic Journal
Articles

Ionospheric response to the weak geomagnetic storm of 1–2 February 2025 in the Weddell Sea Anomaly region: observations from Ukrainian Antarctic Akademik Vernadsky station

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  • Maryna Reznychenko,
  • Oleksandr Bogomaz,
  • Dmytro Kotov,
  • Taras Zhivolup,
  • Kateryna Martynova,
  • Viktor Burmaka,
  • Vyacheslav Kolodyazhnyi
Maryna Reznychenko
Institute of Ionosphere, National Technical University “Kharkiv Polytechnic Institute”, Kharkiv, 61002, Ukraine; Space Research Centre of Polish Academy of Sciences, Warsaw, 00-716, Poland
Oleksandr Bogomaz
Institute of Ionosphere, National Technical University “Kharkiv Polytechnic Institute”, Kharkiv, 61002, Ukraine; Institute of Radio Astronomy, National Academy of Sciences of Ukraine, Kharkiv, 61002, Ukraine
Dmytro Kotov
Institute of Ionosphere, National Technical University “Kharkiv Polytechnic Institute”, Kharkiv, 61002, Ukraine
Taras Zhivolup
Institute of Ionosphere, National Technical University “Kharkiv Polytechnic Institute”, Kharkiv, 61002, Ukraine
Kateryna Martynova
Institute of Ionosphere, National Technical University “Kharkiv Polytechnic Institute”, Kharkiv, 61002, Ukraine
Viktor Burmaka
Institute of Ionosphere, National Technical University “Kharkiv Polytechnic Institute”, Kharkiv, 61002, Ukraine
Vyacheslav Kolodyazhnyi
Institute of Ionosphere, National Technical University “Kharkiv Polytechnic Institute”, Kharkiv, 61002, Ukraine
DOI: https://doi.org/10.33275/1727-7485.1.2026.757
Published July 2, 2026
Keywords
  • electron density,
  • F2-layer,
  • ionosonde,
  • ionosphere,
  • ionospheric storm,
  • negative phase
    • ...More
    Less
How to Cite
Reznychenko, M., Bogomaz, O., Kotov, D., Zhivolup, T., Martynova, K., Burmaka, V., & Kolodyazhnyi, V. (2026). Ionospheric response to the weak geomagnetic storm of 1–2 February 2025 in the Weddell Sea Anomaly region: observations from Ukrainian Antarctic Akademik Vernadsky station. Ukrainian Antarctic Journal, 24(1(32), 50-59. https://doi.org/10.33275/1727-7485.1.2026.757

Copyright (c) 2026 Ukrainian Antarctic Journal

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Abstract

The ionospheric response to the weak geomagnetic storm of 1–2 February 2025 was studied within the Weddell Sea Anomaly region. The behavior of the key ionospheric parameters (NmF2 and hmF2) was analysed using ionosonde observations from the Ukrainian Antarctic Akademik Vernadsky station and vertical total electron content derived from Global Navigation Satellite System measurements. A pronounced nighttime depletion was observed in both ionosonde F2-layer peak electron density (NmF2) and the total electron content values on 1 and 2 February 2025. This indicates the development of the negative phase of the ionospheric storm and a weakening of the Weddell Sea Anomaly under minor geomagnetic disturbances. NmF2 decreased by a factor of ~2 on 1 February and by a factor of ~5 on 2 February, while the total electron content was reduced by ~15–20 TECU and ~25 TECU, respectively. The negative phase penetrated farther toward the equator on 1 February, whereas on 2 February it remained restricted to high- and mid-latitude regions. Notably, such a strong depletion in NmF2 occurred despite a significant uplift of the F2-layer peak height (hmF2) by ~60–70 km. No clear signatures of vertical plasma transport driven by the penetration electric field of magnetospheric origin were found in the observed hmF2 variations. The likely reason for such a depletion in ionospheric plasma density is storm-time changes in neutral composition associated with upwelling, reduction in the O/N2 ratio, and transport of the composition disturbance zone by thermospheric winds from high to low latitudes. These results demonstrate that even minor geomagnetic storms can substantially modify the ionosphere–thermosphere system over Antarctica and significantly impact the Weddell Sea Anomaly.

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