Home – Home – Jornals – Atmospheric and Oceanic Optics 2025 number 9

The use of vortex laser radiation can significantly increase the information capacity of data transmission channels in free-space optical communication systems. However, atmospheric turbulence substantially limits the application of such systems. This work analyzes results of experimental study of the influence of different atmospheric turbulence conditions on vortex laser radiation characteristics. Vortex fields were generated using a phase light modulator; initial distributions of vortex beam intensity were represented by sets of concentric rings. An increase in the topological charge increased the number of those rings and reduced their thickness. It was found that, despite equal initial beam sizes, the diffractive beam size increased with the topological charge by the end of a 500-meter atmospheric propagation path, thus reducing random wandering of beam energy centroid. As the topological charge increases, the relative turbulence-induced broadening also decreases and the scintillation level rises. No dependence was found between the beam topological charge and the radius of the spatial correlation of turbulent intensity fluctuations. The experimental results supplement existing knowledge about the propagation of vortex laser radiation in a turbulent atmosphere and can be used in the design of free-space optical communication systems.

Determination of the spectrum structure, i.e., finding the empirical energy levels of molecules, is a relevant and important task of spectroscopy. For deuterated hydroxyl (OD), such information is absent in known spectroscopic databases. Therefore, empirical energy levels of ¹⁶OD were determined in this work. For the first time, the critical analysis of 3138 available experimental frequencies of rotational and vibrational-rotational transitions of ¹⁶OD molecule in X ²П ground electronic state was performed using the Ritz combination principle. Transitions with hyperfine splitting were not considered. The transition frequencies weighted in accordance with the experimental errors were processed by the RITZ program code. The analysis of the dimensionless weighted deviations enabled us to exclude from the consideration those frequencies for which the weighted deviation exceeded four. The resulting set of 2984 transition frequencies made possible processing with a standard deviation of 1.24. As a result of critical evaluation, a set of 864 empirical RITZ energy levels was obtained with an appropriate uncertainty for each level. The found empirical RITZ energy levels were compared with those calculated in [15].

Elements of the anisotropy tensor of wind turbulence in the surface air layer are calculated based on experimental data at different observation points. Their statistics, seasonal and daily variations, and dependence on temperature and wind stratification in the surface layer are analyzed. It is noted that the annual average values of the elements are highly stable despite the elements are significantly variable over short time intervals. The analysis of the effects of temperature and wind stratification of the surface air layer shows the stratification to have the greatest effect on the diagonal elements of the anisotropy tensor.

Atmospheric aerosols transported from deserts is an important factor in oceanography, which affects the productivity of ecosystems, global biochemical cycles, and climate. In this work, we study main optical characteristics of aerosol over the Black Sea derived from measurements onboard Professor Vodyanitsky research vessel (130th and 134th cruises) in March-April 2024 and 2025. In situ, satellite, and model data for days with intense dust transfer from the Sahara Desert are analyzed. It is shown that the concentrations of suspended particles measured with an Espada M3 detector at the time of dust aerosol detection over the region under study exceeded the background values by more than three times. For days with dust transport, the photometric data differed by more than 2.5 times from the background values for the Black Sea region. The results supplement the array of optical characteristics of the atmosphere over the coastal zone and the Black Sea water area and can be useful in verification of the accuracy of standard atmospheric correction algorithms for satellite data.

We discuss the results of aerosol studies during high-latitude (81-88.5° N) expedition “North Pole-41” in the Arctic Ocean. The average mass concentrations of black carbon (еВС) in the surface atmospheric layer over 20 months of measurements were 19 ng/m³; volume concentrations of submicron ( V_f ) and coarse ( V_с ) aerosol were 0.41 and 0.65 μm³/cm³, respectively. The average aerosol optical depth of the atmosphere at a wavelength of 0.5 μm and the Ångström exponent in the spring periods of 2023 and 2024 were 0.095 and 1.52, respectively. The seasonal variations in the aerosol and black carbon concentrations were well manifested in high-latitude (near-pole) part of the Arctic Ocean. The concentrations were maximal in spring (еВС = 29 ng/m³, V_f = 0.61 μm³/cm³, V_c = 0.77 μm³/cm³) and minimal in June - October (еВС = 11 ng/m³, V_f = 0.13 μm³/cm³, V_c = 0.26 μm³/cm³). The average aerosol characteristics measured in near-pole zone are several-fold lower than the long-term data in more southern regions of the ocean and at polar stations (Barentsburg and “Cape Baranov”).

The paper presents results of lidar monitoring of the atmosphere over Tomsk in winter 2023/24. The work studies the thermal regime of the middle atmosphere with emphasis on disturbances in the stratosphere caused by sudden stratospheric warmings (SSWs), including statistics on the vertical temperature distribution (VTD) for further analysis. During this period, 90 temperature profiles were calculated from lidar returns of molecular (Rayleigh) and spontaneous Raman scattering in the altitude range from 10 to 70 km. The annual cycle of the vertical temperature distribution is characterized by stratospheric warmings and their destruction in winter and spring, VDT stabilization in warm season, and VTD destabilization in fall with transition to winter SSW phase. In most cases, the vertical temperature distribution in April-October was in good agreement with the model distribution. It has been found that during two stratospheric warming events in winter 2023/24, a splitting of circumpolar vortices occurred at the time of their maximum manifestation (on December 13, 2023, and February 18, 2024). The results are particularly interesting for understanding climate change in Western Siberia.

This work studies spatial distribution of accumulation levels of 21 compounds of polycyclic aromatic hydrocarbons (PAHs) in the snow cover of Baikal Natural Territory in winter 2021/2022. The highest PAHs concentrations were revealed in industrial cities of the Baikal Region (14-3400 μg/m²), and the lowest ones, on the lake ice in Northern Baikal basin (2.0-7.7 μg/m²). The local character of PAHs expansion near source of their emission is revealed. Total PAHs income onto Lake Baikal surface during winter 2021/2022 was 128.8 kg, high values were determined for phenanthrene, fluorantene, pyrene, benzo(b)fluorantene, benzo(k)-fluorantene. The spatial distribution, diagnostic ratios, and factor analysis of PAHs have revealed main sources of air pollution by this class of compounds during a cold year period, i.e. carbon and liquid fuel burning. We assessed the degree of snow cover pollution by coefficients of ecological risk ( RQ ) with a high contribution of benzo(b)fluorantene.

During long-term measurements at two lidar stations of Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, pronounced aerosol layers were recorded in the stratosphere over Tomsk on February 5 and 6, 2025. The analysis of lidar and additional meteorological information showed the occurrence of a rather rare phenomenon for middle latitudes, polar stratospheric clouds, at that time. The constructed back trajectories of air masses at the altitudes of the formation of polar stratospheric clouds over Tomsk showed that abnormally cold air masses were brought from the polar regions of Norway and Greenland. The results can be useful for specialists in atmospheric physics, climatology, and environmental protection.

Ozone in the surface air layer in high concentrations is a powerful oxidizer that has a negative impact on biological objects and environmental elements. Therefore, it is very important to study the dynamics of its concentration in all regions of the planet. In the work, based on annual monitoring data, ozone concentrations in Russia in 2024, mesoscale differences in its content in individual regions, and its vertical distribution according to aircraft sounding data are considered; the comparison with hygienic standards is made. It is shown that the average annual ozone content in the surface air layer across Russia varied from 17 to 92 mg/m³; maximum hourly concentrations, from 90 to 222 mg/m³. In the annual course, the maximum concentration is usually observed in spring under background conditions and in summer in urban areas. A secondary maximum became noticeable at background stations in early autumn. The magnitude of mesoscale differences in concentrations reaches 50-70 mg/m³ and changes significantly during the day and year. In most measurement points, the maximum permissible daily average concentrations established by the domestic hygienic standard were exceeded: maximum one-time, daily average, and annual average. The current situation necessitates wide public awareness of the monitoring results and the development of environmental protection measures to reduce the level of ozone and its precursors concentration in the ground layer of air.

Studying the characteristics and dynamics of stratospheric polar vortices requires the correct determination of their edges. Polar vortex delineation methods are mainly based on the values of potential vorticity (PV) or geopotential (GPT). The problem in directly comparing the PV and GPT methods is that the former determines the vortex edge on isentropic surfaces, while the latter does it on isobaric ones. In this paper, we present an algorithm developed to adequately compare the results of polar vortex delineation by these methods. The algorithm is based on projecting the vortex edges onto isopotential surfaces (i.e., surfaces of constant geopotential height), same for both methods. Application of the algorithm to delineating the 2019 Antarctic polar vortex showed, in particular, the following: (1) during the period of the vortex stable state (June 1 - August 31), its area on isopotential surfaces estimated by the GPT method exceeds the area estimated by the PV method by 16.17-21.20 million km² in the range of geopotential heights 20.89-24.37 km, respectively; (2) the dynamics of the vortex edge and area estimated by both methods are generally similar, but the vortex edges obtained by the GPT method are smoother, and the strong irregularity of the vortex edges obtained by the PV method leads to abrupt changes in the vortex area. The algorithm will be useful in studying the dynamics of polar vortices from the beginning of their formation to the moment of breakup in both hemispheres.

The kinetics processes of triplet bands of molecular nitrogen were studied in air at pressures of 0.03-1 Torr. The dependences of the ratios of the spectral density of radiation energy of four bands of the first positive system of nitrogen to two bands of the second positive system of nitrogen are demonstrated. The results of simulation and experimental measurements show an increase in the ratio of the intensities of the bands of the first positive system to the intensities of the second positive system with a decrease in the pressure. It was found that this is due to an increase in the rate of quenching of the B³П_g state by nitrogen molecules with an increase in atmospheric density. These results explain the reason for the change in the color of red sprites with a decrease in the altitude above sea level starting from about 50 km.

Land degradation and increasing deflationary processes make urgent the development of effective methods for monitoring atmospheric and soil processes. The paper describes SAM-V autonomous monitoring system designed at Institute of Monitoring of Climatic and Ecological Systems, Siberian Branch, Russian Academy of Sciences (Tomsk). Its advantages are: domestic software which enables data collection with a preset frequency, variability of configuration, ease of transportation and installation, and high measurement accuracy. The system was installed by scientists of the Federal Research Center of Agroecology, Russian Academy of Sciences, on a local deflation outbreak of 182.6 ha in area in the Republic of Kalmykia. New soil and atmospheric parameters received with this system will be used to analyze aeolian processes in order to scientifically substantiate phytomeliorative measures for the restoration of degraded lands. In the future, it is planned to expand the use of SAM-V system on other scientific objects.