Dependence of occurrence probability of the sporadic Eₛ layer on solar activity at different values of Eₛ critical frequency

Ekaterina Voronova; Konstantin Ratovsky; Aleksandr Timchenko; Anastasiya Belinskaya; Egor Senyagin

doi:10.12737/stp-123202609

UDC 523.9 UDC 523.98

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DEPENDENCE OF OCCURRENCE PROBABILITY OF THE SPORADIC Eₛ LAYER ON SOLAR ACTIVITY AT DIFFERENT VALUES OF Eₛ CRITICAL FREQUENCY Dependence of occurrence probability of the sporadic Eₛ layer on solar activity at different values of Eₛ critical frequency

АА Аа

Published in Solar-Terrestrial Physics · Volume 12, Issue 3 · Pages 81–88 · Rubric: Results of current research

DOI: https://doi.org/10.12737/stp-123202609 · EDN: AVTAGH

Received: 27.02.2026 Accepted: 15.05.2026 Published: 19.09.2026 Language of publication: ENG

Authors

Ekaterina Voronova

Konstantin Ratovsky

ORCID

Aleksandr Timchenko

ORCID

Anastasiya Belinskaya

ORCID

et al.

Egor Senyagin

Ekaterina Voronova

Institute of Solar Terrestrial Physics SB RAS Russian Federation · Irkutsk

Konstantin Ratovsky

Academic degree: candidate of physical and mathematical sciences

Institute of Solar-Terrestrial Physics SB RAS Russian Federation · Irkutsk

ORCID

Aleksandr Timchenko

West Department of Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation RAS Russian Federation · Kaliningrad

ORCID

Anastasiya Belinskaya

Academic degree: candidate of physical and mathematical sciences

Trofimuk Institute of Petroleum Geology and Geophysics SB RAS Russian Federation · Novosibirsk

ORCID

Egor Senyagin

West Department of Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation RAS Russian Federation · Kaliningrad

ABSTRACT

The aim of the paper is to study the dependence of the occurrence probability of the sporadic Eₛ layer on solar activity at different values of the Es critical frequency. The paper uses data from ionosondes at Irkutsk (52.3° N, 104.3° E), Kaliningrad (54.36° N, 20.12° E), and Novosibirsk (54.84° N, 83.23° E). A new method for correlation analysis of the relationship between the Es occurrence probability and solar activity has been developed. The method involves calculating the correlation coefficients R between annual average values of the solar activity index F10.7 and annual average occurrence probabilities of sporadic Eₛ layer, whose critical frequency fₒEₛ is in the range fᵢ÷fᵢ₊₁. As a result of applying the new method, we have found that the correlation coefficients are negative for the fₒEₛ ranges of 1–2 and 2–3 MHz and positive for 4–5 MHz for all three stations; however, the results for fₒEₛ>5 MHz differ for different stations. The obtained results are interpreted on the basis of three factors of solar activity influence: 1) increase in photoionization; 2) weakening of the zonal component of the prevailing wind; 3) increase in absorption of radio waves in the underlying layers of the ionosphere.

KEYWORDS

ionosphere, sporadic ionosphere, solar activity, correlation coefficients

Funding

The research was financially supported by the Russian Science Foundation (Grant No. 25-17-00187 [https://rscf.ru/project/25-17-00187/]). The work was financially supported by the Ministry of Science and Higher Education of the Russian Federation in terms of observations and primary data processing (Project FWZZ-2026-0051)

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Editor-in-Chief

Geliy Zherebtsov

solater@iszf.irk.ru

Deputy Editor-in-Chief

Aleksandr Stepanov

stepanov@gaoran.ru

Deputy Editor-in-Chief

Alexander Potapov

potapov@iszf.irk.ru

Executive Secretary of Editorial Board

Natalia Polyushkina

npol@iszf.irk.ru

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GOST

Voronova E. Y., Ratovsky K. G., Timchenko A. V., Belinskaya A. Y., Senyagin E. D. Dependence of occurrence probability of the sporadic Eₛ layer on solar activity at different values of Eₛ critical frequency // Solar-Terrestrial Physics. 2026. no. 3. pp. 81-88. DOI: https://doi.org/10.12737/stp-123202609. EDN: AVTAGH. (Date of access 24.09.2026).

MLA

Ekaterina Voronova, Ratovsky K. G., Timchenko A. V., Belinskaya A. Y., Senyagin E. D.. "Dependence of occurrence probability of the sporadic Eₛ layer on solar activity at different values of Eₛ critical frequency." Solar-Terrestrial Physics 12.3 (2026): 81-88. DOI: https://doi.org/10.12737/stp-123202609. EDN: AVTAGH.

APA

Voronova E. Y., Ratovsky K. G., Timchenko A. V., Belinskaya A. Y., Senyagin E. D. (2026). Dependence of occurrence probability of the sporadic Eₛ layer on solar activity at different values of Eₛ critical frequency. Solar-Terrestrial Physics, 12(3), 81-88. https://doi.org/10.12737/stp-123202609 EDN: AVTAGH.

Chicago

Ekaterina Voronova, Ratovsky K. G., Timchenko A. V., Belinskaya A. Y., Senyagin E. D.. "Dependence of occurrence probability of the sporadic Eₛ layer on solar activity at different values of Eₛ critical frequency." Solar-Terrestrial Physics 12, no. 3 (2026): 81-88. https://doi.org/10.12737/stp-123202609. EDN: AVTAGH.

WIKI

{{cite journal | author = Voronova E. Y., Ratovsky K. G., Timchenko A. V., Belinskaya A. Y., Senyagin E. D. | title = Dependence of occurrence probability of the sporadic Eₛ layer on solar activity at different values of Eₛ critical frequency | journal = Solar-Terrestrial Physics | year = 2026 | volume = 12 | issue = 3 | pages = 81-88 | doi = 10.12737/stp-123202609 }} EDN: AVTAGH

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DEPENDENCE OF OCCURRENCE PROBABILITY OF THE SPORADIC Eₛ LAYER ON SOLAR ACTIVITY AT DIFFERENT VALUES OF Eₛ CRITICAL FREQUENCY Dependence of occurrence probability of the sporadic Eₛ layer on solar activity at different values of Eₛ critical frequency

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