Solar-Terrestrial Physics Solar-Terrestrial Physics Solar-Terrestrial Physics 2500-0535 6a9c168032807fdbab8763a7 10.12737/stp-123202609 avtagh Results of current research Results of current research Results of current research 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 Воронова Екатерина Андреевна Voronova Ekaterina Yurevna https://orcid.org/0000-0002-0847-3553 Ратовский Константин Геннадьевич Ratovsky Konstantin Gennadyevich ratovsky@iszf.irk.ru

кандидат физико-математических наук;

candidate of physical and mathematical sciences;

 https://orcid.org/0000-0003-0576-5443 Тимченко Александр Владимирович Timchenko Aleksandr Vladimirovich aleksandr.timchenko77@gmail.com https://orcid.org/0000-0003-2254-6138 Белинская Анастасия Юрьевна Belinskaya Anastasiya Yuryevna belinskayaay@ipgg.sbras.ru

кандидат физико-математических наук;

candidate of physical and mathematical sciences;

 Сенягин Егор Дмитриевич Senyagin Egor Dmitrievich senaginegor@gmail.com Институт солнечно-земной физики СО РАН Иркутск Россия Institute of Solar-Terrestrial Physics SB RAS Irkutsk Russian Federation Институт солнечно-земной физики СО РАН Иркутск Россия Institute of Solar-Terrestrial Physics SB RAS Irkutsk Russian Federation Калининградский филиал Института земного магнетизма, ионосферы и распространения радиоволн им. Н.В. Пушкова РАН Калининград Россия West Department of Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation RAS Kaliningrad Russian Federation Институт нефтегазовой геологии и геофизики им. А.А. Трофимука СО РАН Новосибирск Россия Trofimuk Institute of Petroleum Geology and Geophysics SB RAS Novosibirsk Russian Federation Калининградский филиал Института земного магнетизма, ионосферы и распространения радиоволн им. Н.В. Пушкова РАН Калининград Россия West Department of Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation RAS Kaliningrad Russian Federation 19 09 2026 19 09 2026 12 3 81 88 27 02 2026 15 05 2026 © 2026 Воронова Е.А., Ратовский К.Г., Тимченко А.В., Белинская А.Ю., Сенягин Е.Д. © 2026 Voronova E.Y., Ratovsky K.G., Timchenko A.V., Belinskaya A.Y., Senyagin E.D. 2026 Воронова Екатерина Андреевна, Ратовский Константин Геннадьевич, Тимченко Александр Владимирович, Белинская Анастасия Юрьевна, Сенягин Егор Дмитриевич Voronova Ekaterina Yurevna, Ratovsky Konstantin Gennadyevich, Timchenko Aleksandr Vladimirovich, Belinskaya Anastasiya Yuryevna, Senyagin Egor Dmitrievich https://zh-szf.ru/en/nauka/publications/6a9c168032807fdbab8763a7/view

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.

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.

 ionosphere sporadic ionosphere solar activity correlation coefficients ionosphere sporadic ionosphere solar activity correlation coefficients 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) 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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