The results of analysis of the experimental data collected on 5 September 2021 on 557.7 and 630 nm artificial airglow of the ionosphere induced by powerful HF radio waves at the SURA facility are presented. For optical measurements, a photometric suite located directly next to the SURA facility was used. Fast variations in the atmospheric emission intensity at 557.7 nm, 630 nm, and 391.4 nm with a three-channel photometer and spatial–temporal variations in the 557.7 nm with a CCD camera were measured. An ionospherically reflected pump wave and the stimulated electromagnetic emission (SEE) were recorded. Background ionospheric conditions were registered with ionosonde. For the first time, an increase in the 557.7 nm emission intensity induced by the SURA facility radiation was found concurrently with a partial blocking ionosphere in the F-region and suppression HF-induced phenomena in the F-region (the 630 nm airglow increase and SEE generation, powerful radio wave anomalous absorption) during the sporadic E-layer ($E_s$) development. Additionally, we managed to obtain images showing moving spots of the SURA-induced 557.7 nm emission increased intensity at the $E_s$ layer heights.

This paper presents the first results of a coordinated experiment on the ionospheric plasma response to high‐frequency (HF) overdense heating, conducted using the SURA heating facility and the Ionosfera‐M satellite. The experiment combined ground‐based observations with in situ satellite measurements, enabling a comprehensive study of artificial ionospheric disturbances. During the experiment, the SURA facility transmitted HF waves into the ionosphere toward the magnetic zenith, while Ionosfera‐M and ground‐based instruments measured various ionospheric plasma characteristics in the modified region. The penetration of the pump wave energy up to the satellite height was observed as well as some broadening of VLF noise spectrum and signatures similar to the main ionospheric trough in the HF‐disturbed region. The data analysis revealed a coincidence of the regions of artificial airglow generation and electron density depletion near the magnetic zenith. The results demonstrate an efficiency of combining ground‐based and satellite studies of the HF‐pump induced phenomena.

The paper presents experimental data on the observation of artificial airglow of the ionosphere induced by HF radio wave pumping by the SURA heating facility during the presence of a blocking sporadic E layer of the ionosphere. Optical observations were carried out on 5 August 2024 using a three-channel photometer and CCD cameras with narrow-band filters. Emission of atomic oxygen at the wavelength $\lambda$ = 557.7 nm (green line), as well as airglow close to the red line of atomic oxygen at $\lambda$ = 630 nm and the band of molecular nitrogen ions $1NG{N}_2^{+}(0-0)$ at $\lambda$ = 391.4 nm (blue band), were recorded. The induced emission intensity in the green line reached ∼270 R, larger than ever measured. Additional lower-intensity glow spots in the green line southwest and northeast of the main spot (∼12° from zenith), detected by the CCD camera, could be due to the side lobes of the SURA antenna pattern. The atypical behavior of the time course of the intensity in the red line with sharp fronts of increase and decrease may indicate the detection of emission lines of hydroxyl groups in the OH(9-3) and OH(5-0) bands, spectrally close to 630 nm. More detailed analysis of the results obtained and new similar experiments will lead to a deeper understanding of the processes occurring in the upper atmosphere/lower ionosphere during conditions of high solar activity.

This paper presents the results of processing GNSS data during powerful X- and M-class solar flares over the European part of the Russian Federation in the 25th solar cycle in 2022–2024. We revealed responses of median variations in TEC during the emission of solar flares when the studied region was illuminated by the Sun, as well as less intense but longer-lasting disturbances of the ionosphere during geomagnetic activity. It was impossible to determine an unambiguous effect of navigation signals from solar flares on the signal-to-noise ratio.