Validation of F2-layer critical frequency variations in the ionosphere with radio observations of solar bursts

• Published in: Journal of atmospheric and solar-terrestrial physics Vol. 245; p. 106056
• Main Authors: Stanislavsky, Aleksander A., Bubnov, Igor N., Koval, Artem A., Stanislavsky, Lev A., Yerin, Serge N., Zalizovski, Andriy V., Lisachenko, Volodymyr M., Konovalenko, Oleksander O., Kalinichenko, Mykola M.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2023
• Subjects: Critical frequency; F2 layer; Ionosonde measurements; Ionosphere; Radio astronomical observations; Solar bursts; Ionosonde measurements; Critical frequency; Solar bursts; F2 layer; Radio astronomical observations; Ionosphere
• ISSN: 1364-6826; 1879-1824
• DOI: 10.1016/j.jastp.2023.106056

The high-frequency (HF) ionospheric cutoff restricts the possibilities of radio astronomical observations from the Earth, but on the other hand, it allows one to estimate the F2-layer critical frequency of the ionosphere. This effect has been measured using a new active antenna meant for receiving cosmic radio emission in the frequency range 1–40 MHz. The instrument was implemented near the Ukrainian T-shape Radiotelescope, second modification (UTR-2) and serves as a prototype of the HF antenna for a future radio array on the farside of the Moon. We detected directly a storm of solar radio bursts on May 22, 2021 and observed clearly their cutoff due to the ionosphere. For comparison our analysis of the experimental data was supplemented by simultaneous measurements from ionosondes located close to the UTR-2. The distance between the closest ionosonde near Zmiiv (Kharkiv region, Ukraine) and the radio astronomical antenna used in the experiment is 46.5 km. Results obtained from the solar radio records are consistent with the ionosonde data. We show that such an antenna implementation provides us with new opportunities to study the F2-layer critical frequency of the ionosphere. •Radio astronomical observations are used for the study of F2-layer critical frequency variations.•Two independent methods, vertical ionosphere radiosonding and radio astronomical studies of type-III solar bursts, are combined.•The bursts play the role of probing signals on the radio transparency.•The frequency–time analysis of solar bursts and ionosonde data has shown that their agreement was promising.