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Calculated carbon dioxide broadening coefficients of sulfur dioxide lines at a room temperature are presented. The calculations are performed for the ν₁ + ν₃ band, rotational quantum numbers vary in the ranges of J up to 100 and of K_a up to 20. Based on the experimental data the semi-empirical method parameters are determined; the computed broadening coefficients are in good agreement with the literature data.

Contributions of stable dimers to the water continuum in the 1600 and 8800 cm^-1 bands are examined. They are found as the difference between experimental data and the calculation data within the asymptotic line wing theory taking into account the violation of the longwave approximation for the molecular centers of mass. The stable dimer contribution is close in value to the contribution due to all other pair interactions and decreases with increasing temperature. The estimate of the equilibrium constant of the dimer formation reaction is derived proceeding from the temperature dependence of the classical interaction potential of water molecules describing the temperature behavior of the second virial coefficient.

In 2021, concentrations and elemental chemical composition of the inorganic part of solid snow impurities were studied on the territory of the Norilsk Industrial District. Based on the analysis of these data, a list of priority polluting chemical elements is compiled (Ni, Cu, Cd, Co, Sn, Pb, B, and Zn) and a method for quantifying the contribution of atmospheric emissions from Nadezhda Metallurgical Plant to aerosol pollution of the territory is suggested. In the sub-latitudinal direction, emissions from this plant predominate in dust pollution of the air at a distance of up to 7 km from the source.

In the Arctic, global warming is 2-3 times faster than over other regions of the globe. As a result, noticeable changes are already being recorded in all areas of the environment. However, there is very little data on such changes in the Russian Arctic. Therefore, to fill the gap in the data on the vertical distribution of the gas and aerosol composition of air in this region, an experiment was carried out on the Tu-134 Optical laboratory aircraft in September 2020 to sound the atmosphere and water surface over the water areas of all seas in the Russian Arctic. This paper analyzes the spatial distribution of methane. It is shown that during the experiment its concentration was the highest over the Kara Sea (2090 ppb), the lowest over the Chukchi Sea (2005 ppb). The East Siberian and Bering seas were slightly different from the Chukchi Sea in its content. Average values of CH₄ are characteristic of the Barents (2030 ppb) and the Laptev Seas (2040 ppb). The difference in the concentrations between the level of 200 meters and the free troposphere reached 150 ppb over the Kara Sea, decreased to 91 and 94 ppb over the Barents and Laptev Seas, and further decreased over the East Siberian, Chukchi and Bering Seas to 66, 63 and 74 ppb, respectively. Horizontal heterogeneity in the distribution of methane over the Arctic seas is the greatest over the Laptev Sea, where it reaches 73 ppb. It is 2 times higher than over the Barents and Kara Seas, and 5-7 times higher than over the East Siberian and Bering Seas.

This paper is devoted to assessing the long-term variability of the parameters of sudden stratospheric warmings (SSW) from 1979 to 2021. The values of the mean zonal air temperature at a latitude of 80°N and zonal average wind speed at 60°N at altitudes of 10 hPa are used as a criterion for estimating the SSW. Major SSWs are classified according to their types - with split of the polar vortex (PW) and with PW displacement. Estimates are made of the variability of such SSW parameters as the number of events per winter, SSW type, SSW duration, start date and maximal temperature during SSW over the past 42 years. No trend changes are found, but oscillatory behavior of the parameters is observed in the high-latitude stratosphere.

The results of experiments carried out in the Large Aerosol Chamber of IAO SB RAS during 2021-2022 to study the optical characteristics of smoke aerosol with a long aging time (up to 2-3 days) are presented. The influence of the evolution of optical characteristics of pyrolysis and mixed smokes on the radiative forcing of smoke aerosol (RFA) at the top of atmosphere in the Arctic region in summer is estimated. It is shown that for pyrolysis smokes, the main factor that determines the time dependence of RFA is the evolution of the aerosol optical thickness, while for mixed smokes, it is also necessary to take into account the temporal variability of the single scattering albedo of aerosol particles. The dependence of RFA on underlying surface types and illumination conditions typical for the Arctic region is considered for different modes of biomass combustion.

An original statistical model of laser pulse propagation in a scattering medium is considered, which makes it possible to calculate the power of a lidar signal taking into account scattering effects of any multiplicity. A comparative analysis of the temporal structure of the signal obtained using the model suggested and alternative methods is carried out. The features of the propagation of a laser pulse from a ground-based lidar in continuous cirrus clouds are studied taking into account the effects of multiple scattering. The dependence of the multiple scattering background on the cloud optical and microphysical characteristics (extinction coefficient, degree of roughness, size and shape of ice particles) and parameters of the lidar receiving system is studied. The simulation results indicate a high sensitivity of the part of the echo signal due to multiple scattered light to variable parameters, which should be taken into account when setting and solving inverse problems.

The applicability of semiconductor methane sensors, designed to detect explosive concentrations of gas in rooms, to the study of background concentrations of methane in the atmosphere and its emissions from the water body surface is studied. An experimental prototype of the methane sensor is designed, for which, in order to increase the accuracy of determining the methane content in air, a calibration plan is suggested, which takes into account the humidity, temperature, and pressure of the environment. Laboratory and field experiments show that the TGS series sensors are capable of detecting methane concentration changes from 0.1 ppm and higher and can be mounted in floating chambers used to determine methane emissions from the water surface. An experimental setup is described. The results of calibration and selection of the best parametric model are presented. Recommendations for further development of the device are given.

The paper presents the results of the development of an active optical system (a laser monitor) to form enhanced images simultaneously in the visible and near-IR spectral regions. Imagining is carried out in the active medium of a manganese atom brightness amplifier. Images are formed for a time corresponding to the amplification (generation) pulse, which is about 25 ns for the visible region and 35 ns for the IR. Image recording is carried out using digital cameras, including those based on a Russian-made InGaAs sensor. Images of processes accompanied by background radiation formed by a single pulse of a brightness amplifier based on manganese chloride vapors are shown for the first time.

Methods for measuring the salinity of seawater are considered. The results of an experimental study of samples of common and sea salt solutions with different salinity, poured into a hollow trihedral optical glass prism are presented. To measure the angles of refraction of light, a goniometric system was used, the minimum deviation method was implemented, which has a high accuracy of determining the refractive index. With dispersion analysis of experimental results, it is proved that the refractive index of water does not depend on its salt composition. An equation is suggested which describes the dependence of the refractive index on salinity and temperature for a fixed wavelength.