AbstractThis study develops and validates three photochemical inversion models to retrieve atomic oxygen ion density ([O+]) profiles from 630.0 nm airglow emissions in the mid-latitude ionosphere during geomagnetically quiet period. Using passive ground-based instruments and empirical models, the models were tested and compared against electron density data from FORMOSAT-3/COSMIC (F3/C) and DPS-4 digisonde at Irkutsk. Among the models, Inversion Model 3 showed the strongest agreement with observations, particularly in capturing seasonal variations such as the June–July peak and a secondary March–April peak, which were absent in IRI-2012 predictions. These results highlight the potential of Inversion Model 3 for accurate [O+] retrieval, offering a novel approach for monitoring ionospheric variability using passive photometric observations.

The paper discusses the method for recording the radiation of the Earth night atmosphere by the photometric method using a receiver based on a color CCD array with wideband filters. We present the results of the processing and atmospheric radiation data analysis obtained in the GPO ISTP SB RAS, located in the Tory village of the Buryatia Republic, in 2010-2022. As a result, a seasonal variation in the emission intensity in different color channels was obtained, the average luminosity of the night sky was estimated in the R-, G-, B-channels spectral ranges of color camera for Eastern Siberia. As the receivers, the camera «Video scan 11002/O/ P/2001» was used, based on a KODAK CCD KAI-11002.

It is known that atomic oxygen ion (O+) is the dominant chemical constituent of the ionospheric F region, playing a crucial role in the longer lifetime of ionospheric plasma in this region. With the aim of developing a method to observe ionospheric variations using passive instrumentation, three photochemical inversion models were derived to retrieve the O+ density ([O+]) profile from the first excited state of oxygen (O(1D)) 630.0 nm airglow emission intensities. The models are intended to be used in conjunction with the ground-based photometer and spectrometer observations, to provide an additional option for ionospheric F-region observations using passive instrumentation. The performance of the photochemical inversion models was evaluated with a series of observing system simulation experiments and validations by using Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) results, with the derived [O+] showing a high correlation for each with the TIE-GCM model truth. Furthermore, the uncertainty testing results reveal the significant influence of the charge exchange of \(\:{O}^{+}+{O}_{2}\to\:{O}_{2}^{+}+O\) in this photochemical process, while the transitions of the atomic nitrogen (N) excited states were considered in the processes responsible for the production of O(1D) as well (Bates, 1982) to establish a result closer to the real-world condition than the ones derived from general formulas by Link et al. (1981) and Sobral et al. (1993). Consequently, the photochemical inversion model derived from the unbalanced equation by Khomich et al. (2008) was modified according to the photochemical theory for the first time in this study. The results indicate that the modified model is capable of revealing an estimation of the retrieved [O+] similar to both FORMOSAT-3/COSMIC and the digisonde DPS-4 observations at Irkutsk station IR352 by using empirical models and 630.0 nm visible airglow observations from Irkutsk, Russia, manifesting promise for further usage to monitor mid-latitude ionospheric F region variability using passive photometric observations.

We explore bursts of broadband pulsations (PiBs) and airglow using the ISTP midlatitude observatories during substorm activations in the course of severe magnetospheric storms. We detected bursty pulsations in the Pi1B short-period range not only when the boundary of the auroral and field-aligned currents (FACs) region was near Irkutsk, but also when the boundary was up to 10° northward. Earlier, we associated such events with sharp pulses of the solar wind (SW) ram pressure, Pd, and/or to fast substorm-related variations in FACs during superstorms. In this paper, we show observations of such bursty phenomena during substorm sawtooth events (STEs) in the course of two storms both with and without strong Pd pulses or their moderate variations. The possibility of periodic substorm activations during STEs by a global magnetotail instability and excitation of the nighttime Alfvén resonator is discussed. We suppose and test a technique for timing the substorm explosive phase onset by the start of the surge in the spectral power of Pi1B pulsations.

This paper discusses peculiarities of the great mid-latitude aurora that occurred during the extreme magnetic storm on February 11, 1958. This mid-latitude aurora had unusual optical and spectral characteristics, among which, first of all, were very high (10⁵–10⁸ R) intensities of atomic oxygen [OI] 630.0 nm emission and an unusually high ratio of the intensities of two forbidden lines of oxygen [OI] 630.0 nm and 557.7 nm (I₆₃₀/I₅₅₇.₇). In some points, this ratio was as high as 10³–10⁴. Analysis of I₆₃₀ dynamics during other extreme geomagnetic storms and associated geophysical conditions and physical processes in Earth’s ionosphere and magnetosphere allows us to assume that great mid-latitude auroras are formed during intense substorms in main phases of magnetic storms. In order to interpret the observed features of the February 11, 1958 mid-latitude aurora, we propose to examine the mechanism of level [OI] ¹D selective filling in which reactions of resonance recharge of oxygen ions O⁺(²D)+O (³P)→O⁺(⁴S)+O(³P, ¹D) and/or reactions of oxygen atom and molecule collisions with excited components of odd nitrogen can be implemented.

Based on the results of instrumental observations carried out at the Geophysical Observatory of the Institute of Solar–Terrestrial Physics, Siberian Branch, Russian Academy of Sciences, the reaction of the upper atmosphere to the major Khövsgöl earthquake of January 11, 2021 (MW = 6.7), has been analyzed. The response was revealed after the earthquake in the radiation of the Earth’s upper atmosphere in the [OI] 557.7 nm emission. Acoustic–gravity waves propagating from the earthquake’s epicenter zone and arising above the observation point during passing of seismic waves are considered as a possible reason for the excitation of the atmosphere.

In this paper, we consider disturbances in the airglow of the Earth’s upper atmosphere caused by a launch of the Yamal-601 satellite on May 30, 2019. For this purpose, we used the data acquired with an optical system of the Institute of Solar−Terrestrial Physics, Siberian Branch, Russian Academy of Sciences (ISTP SB RAS). The measurements were carried out at the Geophysical Observatory (GPO) of the ISTP SB RAS (~52° N, ~103° E) with a complex of optical instruments—a whole-sky camera, a spectrograph, and a Fabry–Pérot interferometer. According to the data of the KЕО Sentinel camera, an extensive area of airglow was observed along the flightpath; it appeared approximately 2−4 min after the spacecraft’s passage over the GPO and existed for ~20 min. A transversal scale of the spacecraft’s flightpath is estimated approximately as 95–110 km if the spontaneous-emission altitude is assumed to be at ~150 km (and it is about 190–220 km if the spontaneous-emission altitude is ~300 km). We discuss the mechanisms that may result in forming the observed area of airglow, including the mechanisms connected with the physical and chemical interaction of fuel products with atmospheric components and the influence of propagation of a shock wave or short-period internal gravitational waves. Probable causes of the delay observed in appearing the airglow after the spacecraft’s flyby are analyzed.

The dynamics of geomagnetic disturbances and optical airglow at mid-latitude observatories near Irkutsk during a strong magnetospheric storm in the night sector on October 21, 2001, has been studied. During the storm, three 1.5-hour intervals of increase in the solar wind (SW) dynamic pressure, which caused intensification of substorm activity, bursts of broadband geomagnetic pulsations, and 557.7 and 630.0 nm auroral emissions, were observed. During these bursts, the southern boundary of the zone of field-aligned currents and the auroral oval approached the observation points, but remained 5°–7° to the north. Possible mechanisms of the amplification of pulsations and optical emissions are related to the effects of SW pressure changes on the magnetosphere: substorm activations, changes in field-aligned and ionospheric currents, and precipitation of both energetic and thermal/superthermal electrons. The features of the high-frequency part of the pulsation spectrum and their spatial distribution are associated with properties of the ionospheric Alfven resonator and the ionospheric MHD waveguide.

This paper provides a brief overview on optical effects during operation of spacecraft (SC) onboard engines in the lower thermosphere according to observational data from the ISTP SB RAS Geophyisical Observatory. We present the results of detected disturbances in the night airglow during operation of SC vernier engines in the F2-region of the ionosphere in the “Radar–Progress” space experiment. With weights of combustion products of ≤10 kg injected by SC vernier engines, the atmospheric emission of [OI] 630.0 nm atomic oxygen is enhanced. We also show optical effects from the launches and passages of heavy launch vehicles “Energiya” from the Skif-DM spacecraft on May 15, 1987 and “Proton-M” from the Yamal-601 spacecraft on May 30, 2019 from Baikonur in the zone far from the launch site. We explore the possibility of enhanced [OI] 557.7 nm atmospheric emission due to chemical modification of the ionosphere in the E-region during the flight of the Energiya space system.

The paper addresses color characteristics and possible spectral composition of emission of a long-lived (~40 min) meteor trail of uncommon geometry, which was formed due to the bolide passage in the Tunka Valley on November 17, 2017. Analysis of dynamics of RGB channels of the meteor trail colored image shows that during the first ~8 minutes the meteor trail emission might have been contributed by the ionization trail. The ionization trail was formed by particles of the meteor matter neutral and ionized components that were heated to high temperatures on the surface of the main meteoroid and separated from it. We also examine the discussed mechanism of heterogeneous chemical reactions occurring on the surface of meteoric dust (FeS, FeO, etc.) with participation of atoms and molecules of atmospheric gases. The yellowish color of the Tunka bolide meteor trail was assumed to be determined, first of all, by the emission of molecular nitrogen N₂ band within the 570–750 nm spectral range (the first positive system) and/or enhancement of NO*₂ continuum in heterogeneous chemical reactions. The meteor trail emission spectrum should also include relatively bright atomic lines and molecular bands of the meteoric matter and atmospheric gases FeI, MgI, CaI, SiI, NaI, FeO and SO₂, OI, OH, etc.

Peculiarities of 557.7 and 630.0 nm emissions observed in the second step of the magnetic storm main phase at the mid-latitude observatory Tory (52° N, 103° E) on March 17, 2015 are compared with the changes in ionospheric parameters above this station, detected from ionospheric sounding data and total electron content maps. We have found that the intensity of the 557.7 and 630.0 nm emissions noticeably increased after the observatory entered into the longitudinal sector of the developed main ionospheric trough (MIT). The most powerful synchronous increases in intensities of the two emissions are associated with amplification of the westward electrojet during strengthening of the magnetospheric convection. We study the dependence of the ratios between the intensities of 630.0 nm emission recorded in the north, zenith, and south directions on the position of emitting regions relative to the MIT bottom. The SAR arc is shown to appear initially near the bottom of the MIT polar wall and approach the zenith of the station during registration of F3s reflections by an ionosonde, which indicate the presence of a polarization jet near the observation point.

This paper considers a possible mechanism for the formation of long-lived meteoric trails of an unusual geometric shape within the framework of the model of instantaneous destruction of a meteoric body under the action of aerodynamic force and spreading of meteoric matter in the direction transverse to the main motion of the core first proposed in 1979 by S.S. Grigoryan and developed in subsequent years by other authors. In the event under consideration, the long-lived meteor trail was determined by the shape of the meteoroid and its dynamics during the destruction of the meteoroid. The meteor wake began to form near the surface of the meteoroid body during its radial expansion, which is consistent with the model of S.S. Grigoryan instantaneous destruction of a meteoric body under the action of aerodynamic force and transverse expansion when a meteoric body is destroyed by elastic waves. The meteoric trail “forks” in the opposite and radial directions with respect to the flight path of the main meteoroid body. It is noted that the observed lifetimes of long-lived meteor trails (~20–40 min) and their spatial scales (tens to hundreds of kilometers) can be provided by the propagation of large meteoric particles (≥100 μm). These particles have high momentum values, which are preserved during horizontal propagation at atmospheric altitudes with the same density at large distances without a significant loss of velocity. In this case, the glow of the meteor trail can be determined by the classical mechanisms of the intrinsic glow of the meteoric matter and the gaseous components of the atmosphere.

The paper examines the results of optical observations obtained during Radar Progress experiments to study the effects (the occurrence of extensive, faintly luminous regions and a decrease in plasma concentration) arising from a release of fuel-combustion products from spacecraft engines into the upper atmosphere of the Earth. Analysis of the results of controlled experiments on the injection of “plasma-quenching” compositions into the ionosphere at orbital altitudes indicates that the observed increase in [OI] 630.0-nm intensity in the Radar Progress experiments as a consequence of chemical modification of the ionosphere. The contribution of various components of the injected substance (H2, OH, Н2О, CO, and СО2) to the increase in the intensity of atomic oxygen [OI] luminescence at a wavelength of 630.0 nm and to a change in the concentration of the charged component of the upper atmosphere is considered. It is shown that the change in the luminescence intensity and the concentration of the charged component are due to different chemical reactions. The largest contribution to the increase in luminescence intensity is made by the injection of hydrogen and carbon dioxide into the atmosphere, while the decrease in the concentration of plasma particles is mainly caused by the injection of water vapor. It has been found that the characteristic spatiotemporal scales of luminous regions occurring in the upper atmosphere allow them to be recorded by modern spectrophotometric equipment from the Earth’s surface without additional information about the time of ignition of the spacecraft engines.

Studies of the upper atmosphere have to be performed using optical photometric and spectrometric means. Modern devices allow precise photometry of the glow of the night atmosphere — airglow — with high temporal spatial and spectral resolution. As a result, the obtained airglow parameters make it possible to determine the physicochemical properties of the upper atmosphere and observe their variation under the influence of various factors. The National Heliogeophysical Complex, which is being created in Eastern Siberia, is therefore to include a certain set of modern optical instruments. The paper presents the main phenomena that will be investigated by the optical instruments of the complex, provides information on their composition and scientific goals, presents the results of preliminary studies performed using a prototype of the instruments. As a result of the studies, the presence of a significant (about 10 m/sec) vertical wind at various altitudes (100 and 250 km) was established, the importance of taking into account the vertical wind to study the vertical dynamics of the charged component was demonstrated. The long-term dynamics of the vertical wind at an altitude of about 100 km has a pronounced seasonal variations and the absence of diurnal variations, whereas the dynamics of the vertical wind at an altitude of 250 km has a pronounced diurnal variations, which is mostly clearly defined in winter. This suggests the presumed presence of vertical circulation cells at various altitude levels. The possibilities of optical stereoscopy and differential image analysis methods are demonstrated, as applied to the study of fast luminous formations and conducting active ground and space experiments to modify Earth's ionosphere. We report the results of the determination of a three-dimensional picture of a long-lived meteor track with the use of two wide-angle cameras. We propose an algorithm that allows us to get a stereo image of events occurring in the upper atmosphere, recorded simultaneously from different observation points. The joint work of the tools of this complex and the development of cooperation with third-party organizations are shown to be a good enough direction for further study of the vertical dynamics of Earth’s upper atmosphere and space weather phenomena.

In the paper, variations of the night emission intensities in the 557.7 and 630 nm atomic oxygen lines [OI] in 2011–2019 have been analyzed. The analysis is based on data from the ISTP SB RAS Geophysical Observatory. The emission intensities are compared with atmospheric, solar, and geophysical parameters. High correlation coefficients between monthly average and annual average 630.0 nm emission intensities and solar activity indices F10.7 have been obtained. This suggests a key role of solar activity in variations of this emission in the period of interest. Variations of the 557.7 nm emission demonstrate to a greater extent the correlations of the stratospheric zonal wind (QBO.U30 index) with quasi-biennial oscillations. The causes of the weak dependence of the 557.7 nm emission intensity on solar activity in solar cycle 24 are discussed.

We study how the atmospheric aerosol influences the recorded emission of the Earth’s upper atmosphere. The study was performed using the data from an automatic CIMEL CE-318 sun photometer, a part of the global network of ground-based sun photometer stations (AERONET), and observations were made of atomic oxygen [OI] 557.7- and 630-nm emission lines at the Geophysical Observatory of the Institute of Solar-Terrestrial Physics, Siberian Branch, Russian Academy of Sciences (52° N, 103° E). A nonlinear characteristic of the correlation dependence was revealed between the intensities of the 557.7- and 630-nm emissions of the upper atmosphere and the aerosol optical depth (AOD): the correlation coefficients increased for small AOD (below 0.5) and decreased for large turbidities. We identified an observation period with a high positive correlation between the 557.7-/630.0-nm emission intensities and the AOD, presumably associated with vast forest fires.

We analyze the results of a rare long-lived quasisymmetric ellipsoidal-annular meteor trail recorded on November 18, 2017 by two optical all-sky cameras, spaced at a distance of 150 km. The analysis is based on astrometric processing results with the use of baseline measurement methods. We determine spatial-kinematic characteristics of the meteor trail, and find features of its evolution. The ignition and extinction heights of the meteor were in the range 75–120 km. The estimate of the meteor brightness gives the absolute magnitude value of about –7.3m. It is shown that the distribution of all parts of the long-lived meteor trail occurs in the same plane at a height of ~90 km at a speed of ~320 m/s and, apparently, cannot be a consequence of an air mass movement. The total time of the meteor trail observation was more than 30 min. We offer possible explanations for the results obtained in the context of upper atmosphere processes.

The paper presents the results on first synchronous observations of variations in auroral luminosity and geomagnetic field, made with high temporal resolution at the ISTP SB RAS high-latitude station Istok (70° N, 88° E) in September–December 2018. Auroras were recorded with all-sky camera, pulsations in the auroras were recorded by a photometer in four spectral ranges with silicon photomultipliers. Continuous monitoring of geomagnetic pulsations was performed using a LEMI-30 three-component induction magnetometer. Both synchronous bursts of auroras and magnetic field pulsations, as well as disturbances of auroras, not accompanied by disturbances in the geomagnetic field, were observed. We note that the photometer clearly recorded short-period (~20 min) variations in in auroral luminosity. At the same time, some instability of the photometer signal level occurred at sufficiently long time intervals. In the photometer data, there are powerful signal bursts, probably of a hardware nature. Nevertheless, the temporary distribution analysis of the registration moments (registration frequency) of signal bursts indicates the possible dependence of the burst registration frequency on the geomagnetic activity level.

Using vertical sounding data obtained by the Irkutsk digisonde DPS-4 from 2003 to 2016, we have studied the frequency of occurrence of the F1 layer in winter conditions. The frequency of occurrence of the F1 layer in December–January is shown to be more than twice lower than that in February at any level of magnetic activity. At moderate and low solar activity under quiet geomagnetic conditions, the appearance of F1 layer in midlatitudes of the Northern Hemisphere may be caused by active thermodynamic processes, which lead to transformation or destruction of the circumpolar vortex at heights of the middle atmosphere. Such global dynamic changes occurring in the winter strato-mesosphere are often associated with sudden stratospheric warming events, which are accompanied by increased generation of atmospheric waves of various scales. These wave disturbances can propagate upward to the heights of the lower thermosphere and ionosphere, carrying a significant vertical flow of energy and causing variations in the composition, thermodynamic parameters of the neutral atmosphere and ionosphere.