Solar-Terrestrial Physics Solar-Terrestrial Physics Solar-Terrestrial Physics 2500-0535 82249 10.12737/stp-103202414 19TH ANNUAL CONFERENCE “PLASMA PHYSICS IN THE SOLAR SYSTEM”. FEBRUARY 5–9, 2024, SPACE RESEARCH INSTITUTE RAS, MOSCOW, RUSSIA 19TH ANNUAL CONFERENCE “PLASMA PHYSICS IN THE SOLAR SYSTEM”. FEBRUARY 5–9, 2024, SPACE RESEARCH INSTITUTE RAS, MOSCOW, RUSSIA 19TH ANNUAL CONFERENCE “PLASMA PHYSICS IN THE SOLAR SYSTEM”. FEBRUARY 5–9, 2024, SPACE RESEARCH INSTITUTE RAS, MOSCOW, RUSSIA Features of Earth’s lower ionosphere during solar eclipse and sunset and sunrise hours according to measurements by the API method near Nizhny Novgorod Features of Earth’s lower ionosphere during solar eclipse and sunset and sunrise hours according to measurements by the API method near Nizhny Novgorod Бахметьева Наталия Владимировна Bahmetieva Nataliya Vladimirovna nv_bakhm@nirfi.unn.ru

доктор физико-математических наук;

doctor of physical and mathematical sciences;

 Григорьев Геннадий Иванович Grigoriev Gennadiy Ivanovich grig19@list.ru Жемяков Илья Николаевич Zhemyakov Ilia Nikolaevich ilia.zhem@yandex.ru Калинина Елена Евгеньевна Kalinina Elena Evgenevna kalinina@nirfi.unn.ru Лисов Александр Александрович Lisov Aleksander Aleksandrovich lisov@nirfi.unn.ru Научно-исследовательский радиофизический институт Нижегородского государственного университета им. Н.И. Лобачевского Нижний Новгород Россия Radiophysical Research Institute Lobachevsky State University Nizhny Novgorod Russian Federation Научно-исследовательский радиофизический институт Нижегородского государственного университета им. Н.И. Лобачевского Нижний Новгород Россия Radiophysical Research Institute Lobachevsky State University Nizhny Novgorod Russian Federation Научно-исследовательский радиофизический институт Нижегородского государственного университета им. Н.И. Лобачевского Нижний Новгород Россия Radiophysical Research Institute Lobachevsky State University Nizhny Novgorod Russian Federation Научно-исследовательский радиофизический институт Нижегородского государственного университета им. Н.И. Лобачевского Нижний Новгород Россия Radiophysical Research Institute Lobachevsky State University Nizhny Novgorod Russian Federation Научно-исследовательский радиофизический институт Нижегородского государственного университета им. Н.И. Лобачевского Нижний Новгород Россия Radiophysical Research Institute Lobachevsky State University Nizhny Novgorod Russian Federation 29 09 2024 29 09 2024 10 3 121 136 19 04 2024 21 05 2024 https://zh-szf.ru/en/nauka/article/82249/view

We present the results of experimental studies into the response of Earth’s lower ionosphere to a partial solar eclipse. The studies have been carried out using the method of resonant scattering of radio waves by artificial periodic irregularities (APIs) in ionospheric plasma. The irregularities were created in the field of a standing wave when a powerful radio wave, generated by radiation to the zenith by transmitters of the mid-latitude SURA heating facility, was reflected from the ionosphere. During the eclipse, the scattered signal amplitude increased by 30–40 dB, and the relaxation time increased 1.5–2.0 times. In some cases, stratification of the signal amplitude in the D-region was observed due to stratification of the electron density profile. By analyzing altitude profiles of relaxation time, we obtained neutral component temperature and density, height of the turbopause, and turbulent velocity. The velocity of vertical regular motion of plasma at each height was measured from the time variation in the scattered signal phase. From the results of measurements of scattered signal characteristics during four partial eclipses, we have obtained that the neutral component temperature decreases, on average, 50–70 K. Variations in the temperature, vertical plasma velocity, and turbopause level exhibited deep quasi-periodic variations with periods from 15 min to several hours, typical of internal gravity wave propagation. The vertical temperature and velocity profiles showed changes with altitude on scales ranging from 5 to 30 km. Comparison between the results of studies of the lower ionosphere during sunrise-sunset hours has revealed that its response during a partial eclipse and the transition to the night regime is identical. According to the measurements by the partial reflection method, during the August 01, 2008 eclipse there was a decrease in the electron density in the D-region 3–5 times. We have concluded that during an eclipse there was a significant change in both the ionized and neutral components of the atmosphere in the lower ionosphere.

We present the results of experimental studies into the response of Earth’s lower ionosphere to a partial solar eclipse. The studies have been carried out using the method of resonant scattering of radio waves by artificial periodic irregularities (APIs) in ionospheric plasma. The irregularities were created in the field of a standing wave when a powerful radio wave, generated by radiation to the zenith by transmitters of the mid-latitude SURA heating facility, was reflected from the ionosphere. During the eclipse, the scattered signal amplitude increased by 30–40 dB, and the relaxation time increased 1.5–2.0 times. In some cases, stratification of the signal amplitude in the D-region was observed due to stratification of the electron density profile. By analyzing altitude profiles of relaxation time, we obtained neutral component temperature and density, height of the turbopause, and turbulent velocity. The velocity of vertical regular motion of plasma at each height was measured from the time variation in the scattered signal phase. From the results of measurements of scattered signal characteristics during four partial eclipses, we have obtained that the neutral component temperature decreases, on average, 50–70 K. Variations in the temperature, vertical plasma velocity, and turbopause level exhibited deep quasi-periodic variations with periods from 15 min to several hours, typical of internal gravity wave propagation. The vertical temperature and velocity profiles showed changes with altitude on scales ranging from 5 to 30 km. Comparison between the results of studies of the lower ionosphere during sunrise-sunset hours has revealed that its response during a partial eclipse and the transition to the night regime is identical. According to the measurements by the partial reflection method, during the August 01, 2008 eclipse there was a decrease in the electron density in the D-region 3–5 times. We have concluded that during an eclipse there was a significant change in both the ionized and neutral components of the atmosphere in the lower ionosphere.

 ionosphere plasma neutral atmosphere solar eclipse sunrise sunset high-frequency heating artificial periodic irregularities temperature vertical velocity turbulence internal gravity waves SURA facility ionosphere plasma neutral atmosphere solar eclipse sunrise sunset high-frequency heating artificial periodic irregularities temperature vertical velocity turbulence internal gravity waves SURA facility The work was carried out under project No. FSWR-2023-0038 in the basic part of the Government assignment of the Ministry of Science and Higher Education of the Russian Federation. Experiments on generation of APIs by the SURA facility in 2022–2023 were financially supported by RSF (Grant No. 21-72-10131) The work was carried out under project No. FSWR-2023-0038 in the basic part of the Government assignment of the Ministry of Science and Higher Education of the Russian Federation. Experiments on generation of APIs by the SURA facility in 2022–2023 were financially supported by RSF (Grant No. 21-72-10131)

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