The change of the global climate is most pronounced in the Arctic, where the air temperature increases 2 to 3 times faster than the global average. This process is associated with an increase in the concentration of greenhouse gases in the atmosphere. There are publications predicting the sharp increase in methane emissions into the atmosphere due to permafrost thawing. Therefore, it is important to study how the air composition in the Arctic changes in the changing climate. In the Russian sector of the Arctic, the air composition was measured only in the surface atmospheric layer at the coastal stations or earlier at the drifting stations. Vertical distributions of gas constituents of the atmosphere and aerosol were determined only in a few small regions. That is why the integrated experiment was carried out to measure the composition of the troposphere in the entire Russian sector of the Arctic from on board the Optik Tu-134 aircraft laboratory in the period of ​​​​​​​4 to 17 September of 2020. The aircraft laboratory was equipped with contact and remote measurement facilities. The contact facilities were capable of measuring the concentrations of CO₂, CH₄, O₃, CO, NO_x​​​​​​​, and SO₂, as well as the disperse composition of particles in the size range from 3 nm to 32 µm, black carbon, and organic and inorganic components of atmospheric aerosol. The remote facilities were operated to measure the water transparency in the upper layer of the ocean, the chlorophyll content in water, and spectral characteristics of the underlying surface. The measured data have shown that the ocean continues absorbing CO₂. This process is most intense over the Barents and Kara seas. The recorded methane concentration was increased over all the Arctic seas, reaching 2090 ppb in the near-water layer over the Kara Sea. The contents of other gas components and black carbon were close to the background level. In bioaerosol, bacteria predominated among the identified microorganisms. In most samples, they were represented by coccal forms, less often spore-forming and non-spore-bearing rod-shaped bacteria. No dependence of the representation of various bacterial genera on the height and the sampling site was revealed. The most turbid during the experiment was the upper layer of the Chukchi and Bering seas. The Barents Sea turned out to be the most transparent. The differences in extinction varied by more than a factor of 1.5. In all measurements, except for the Barents Sea, the tendency of an increase in chlorophyll fluorescence in more transparent waters was observed.

The primary objective of this complex aerosol experiment was the measurement of microphysical, chemical, and optical properties of aerosol particles in the surface air layer and free atmosphere. The measurement data were used to retrieve the whole set of aerosol optical parameters, necessary for radiation calculations. Three measurement cycles were performed within the experiment during 2013: in spring, when the aerosol generation is maximal; in summer (July), when atmospheric boundary layer altitude and, hence, mixing layer altitude are maximal; and in late summer/early autumn, during the period of nucleation of secondary particles. Thus, independently obtained data on the optical, meteorological, and microphysical parameters of the atmosphere allow intercalibration and inter-complement of the data and thereby provide for qualitatively new information which explains the physical nature of the processes that form the vertical structure of the aerosol field.

This paper introduces the technique of retrieving the profiles of vertical distribution of ozone considering temperature and aerosol correction in DIAL sounding of the atmosphere. The authors determine wavelengths, which are promising for measurements of ozone profiles in the upper troposphere–lower stratosphere. An ozone differential absorption lidar is designed for the measurements. The results of applying the developed technique to the retrieval of the vertical profiles of ozone considering temperature and aerosol correction in the altitude range 6–15 km in DIAL sounding of the atmosphere confirm the prospects of ozone sounding at selected wavelengths of 341 and 299 nm with the proposed lidar. The 2015 ozone profiles retrieved were compared with satellite IASI data and the Kruger model.

A differential absorption lidar (DIAL) system based on optical parametric oscillators (OPO) with nonlinear KTA and KTP crystals is designed. The crystals allow laser radiation tuning in the IR wavelength region. A series of experiments on remote monitoring of methane along a horizontal surface sounding path in the 3300–3430 nm spectral range was carried out. Based on the experimental results, the CH₄ concentrations are retrieved along a surface 800-m path in the spectral range under study with a spatial resolution of 100 m.

Laser ranging methods employing light detection and ranging (LiDAR) technology are widely used for studying the atmosphere and monitoring its state. The purpose of this work is to measure the ozone vertical distribution (OVD) in the upper troposphere–stratosphere by differential absorption LiDAR (DIAL) at 299–341 nm and 308–353 nm and to compare the results with satellite data. А LiDAR complex for measuring the OVD in the altitude range approximately 5–45 km has been created. Here, we analyse the results of ozone LiDAR measurements at wavelengths of 299–341 nm and 308–353 nm between 2017 and 2018 at Siberian LiDAR Station (SLS) and compare them with satellite (Microwave Limb Sounder (MLS)/Aura and Infrared Atmospheric Sounding Interferometer (IASI)/MetOp) measurements of OVD. The retrieved LiDAR OVD profiles in the upper troposphere–stratosphere in comparison with MLS/Aura and IASI/MetOp profiles, as well as the stitched OVD profile in comparison with the mid-latitude Krueger model, confirm the prospects of using the pairs of ozone sounding wavelengths 299–341 nm and 308–353 nm. The average relative difference between LiDAR and MLS/Aura measurements is negative in the altitude range 16–38 km and attains –49.81% at 38 km, and also, the average relative difference between LiDAR and IASI/MetOp measurements is positive in the altitude ranges 6 and 7.40 to 18 km, where it attains 43.68% at 16.80 km, and is negative in the altitude range 6–7.30 km, where it attains – 43.86% at 6.20 km.

Possibilities of using superbroadband nonlinear-optical frequency converters for femtosecond laser pulses in lidar sensing of the atmosphere are analyzed. New biaxial nonlinear crystals in which the conditions of phase and group matching can be satisfied simultaneously are basic elements of frequency converters. A technique for the broadband lidar sensing of the gas composition of the atmosphere based on the differential optical atmospheric spectroscopy and the differential absorption methods is described. The lidar sensing of gas constituents of the atmosphere using frequency converted femtosecond laser radiation is simulated numerically.