Solar-Terrestrial Physics Solar-Terrestrial Physics Solar-Terrestrial Physics 2500-0535 45266 10.12737/stp-81202206 Results of current research Results of current research Results of current research Long-term trend of the ionospheric E-layer response to solar flares Long-term trend of the ionospheric E-layer response to solar flares https://orcid.org/0000-0002-0577-0077 Гивишвили Гиви Васильевич Givishvili Givi Vasilyevich givi@izmiran.ru

доктор физико-математических наук;

doctor of physical and mathematical sciences;

 https://orcid.org/0000-0003-4894-9437 Лещенко Людмила Николаевна Leshchenko Liudmila Nikolaevna ln_lesh@mail.ru Институт земного магнетизма, ионосферы и распространения радиоволн им. Н.В. Пушкова РАН Москва, Троицк Россия Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation RAS Moscow, Troitsk Russian Federation Институт земного магнетизма, ионосферы и распространения радиоволн им. Н.В. Пушкова РАН Москва, Троицк Россия Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation RAS Moscow, Troitsk Russian Federation 25 03 2022 25 03 2022 8 1 51 57 23 06 2021 08 12 2021 https://zh-szf.ru/en/nauka/article/45266/view

Using data from ground-based vertical sounding of the ionosphere (VS) at the station Moscow and five Japanese stations for the period from 1969 to 2015, we have examined the long-term response of the E layer to solar X-ray flares. The analysis relies on the previously developed method for estimating the ratio between rates of ionization by X-rays qx and ultraviolet radiation qu during flares. We confirmed the existence of a long-term (at least covering the 45-year observation period) increase in the proportion of X-rays in the total ionization rate of the ionospheric E layer, characterized by the ratio qx/q, where q=qx+q. The qx/q ratio is shown to increase throughout the period of interest at a rate independent of the solar activity cycle. There is also no dependence of the qx/q trend rate on the season, latitude (26°–56° N), and longitude (37°–28° E).

Using data from ground-based vertical sounding of the ionosphere (VS) at the station Moscow and five Japanese stations for the period from 1969 to 2015, we have examined the long-term response of the E layer to solar X-ray flares. The analysis relies on the previously developed method for estimating the ratio between rates of ionization by X-rays qx and ultraviolet radiation qu during flares. We confirmed the existence of a long-term (at least covering the 45-year observation period) increase in the proportion of X-rays in the total ionization rate of the ionospheric E layer, characterized by the ratio qx/q, where q=qx+q. The qx/q ratio is shown to increase throughout the period of interest at a rate independent of the solar activity cycle. There is also no dependence of the qx/q trend rate on the season, latitude (26°–56° N), and longitude (37°–28° E).

 ionospheric E layer vertical sounding solar flares long-term trend ionospheric E layer vertical sounding solar flares long-term trend

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