Home – Home – Jornals – Atmospheric and Oceanic Optics 2026 number 3

The comparative analysis of experimental self-broadened line width γ and line shift δ coefficients is conducted. The 3641 coefficients γ and 2410 coefficients δ of water vapor molecule are analyzed for the 1000-14000 cm^-1 spectral range. It is found that coefficients γ measured for the same lines in different works systematically differ, with a maximum difference of more than 20%. The shift coefficients δ for many strong lines are not even consistent in sign. Using the semi-classical method and the exact trajectory model the coefficients γ and δ have been calculated for 17 vibrational bands, and a sample of the calculated values of these coefficients is presented for 270 vibrational-rotational transitions.

The development of the world ocean shelf requires the use of a variety of underwater communication equipment. The results of simulation of the shape of electrical pulses generated by 1-ns optical pulses from a photodetector are presented. These pulses propagate through a water layer containing only nanobubble clusters. Scattering from the volume behind the emitter was also taken into account. Attenuation was calculated using Bouguer's law. Cluster scattering efficiency factors were estimated using Mie theory for submicron particles with a refractive index lower than that of water. It was found that the broadening of a 1-ns pulse caused by scattering only by bubstons taking into account the volume behind the emitter does not exceed 0.1 ns at a distance of 20 m. It is shown that nanobubble clusters in transparent water limit the length of underwater optical wireless communication lines by attenuating the radiation. The results can be used in the development of devices for underwater wireless optical communication.

The propagation of high-power femtosecond laser pulses under conditions of their filamentation in air of different pressures is theoretically studied. This approach allows predicting the formation of a nonlinear focus during self-focusing and the filamentation domain on real atmospheric paths hundreds of meters long. This is possible due to the scaling laws that relate the pressure in a propagation medium to the initial parameters of high-power ultrashort laser pulses. Thus, the results of laboratory studies under conditions of increased pressure at distances of several meters are transformed into extended air paths hundreds of meters long at atmospheric pressure. The results allow better understanding of the complex and multifactorial dynamics of filamentation of high-power ultrashort laser radiation and open up new prospects for optimizing and expanding the range of applications based on this phenomenon, in particular, remote diagnostics of atmospheric components and long-range energy delivery. Numerical simulation in this work was performed based on the reduced (time-integrated) nonlinear Schrödinger equation for the optical field envelope during propagation of high-power femtosecond pulses of a titanium-sapphire laser under conditions of a 16-fold change in air pressure. The formation of a multifocal structure of the filamentation domain, which is especially evident under these conditions, is considered in detail.

This review addresses the problem of water body eutrophication and approaches to monitoring this process. It describes key biophysical and chemical markers of water object eutrophication, including the content of chlorophyll- a , suspended solids, and nutrients in the aquatic environment, as well as volatile molecular markers of eutrophication which can be present in the air near the water surface. The comparative analysis of experimental, process-based, and theoretical models of this process is performed. Since the volume and quality of experimental data significantly affect the predictive accuracy of eutrophication models, the review focuses on methods for accumulating these data, including remote and local sensing of water body parameters. Among the latter, laser gas analysis methods for detecting volatile markers of eutrophication near the water surface are considered. Based on a literature review, a list of the most informative volatile molecular markers of eutrophication emitted from the water surface into the atmosphere has been compiled: carbon dioxide (CO₂), hydrogen sulfide (H₂S), methane (CH₄), nitric oxide (N₂O), geosmin, and 2-methylisoborneol. The importance of monitoring phosphorus derivative phosphine (PH₃) as an indicator of the phosphorus cycle and a potential greenhouse gas is noted. The back of data on its sources and the processes leading to its synthesis is emphasized. Based on data on quantum spectral transitions, recommendations are provided for recording PH₃ and other volatile markers of eutrophication near the water-air interface using IR gas absorption spectroscopy.

Studying wind turbine wakes is essential for optimizing wind turbine arrangement within wind farms. Pulsed coherent Doppler lidars (PCDLs) are the most effective tools for such studies. This paper suggests a new method for three-dimensional visualization of wind speed within a wake based on PCDL measurements. Numerical simulation shows that this method enables wind speed deficit estimates with a relative error of no more than 4%. An atmospheric experiment with the use of this three-dimensional visualization method reveals that the wake cross section exhibits a wind speed deficit structure close to an annular distribution, consistent with numerical simulation with the use of LES and RANS methods.

River ecosystems are a key component of the global carbon cycle, facilitating the transformation, transport, and emission of carbon. They ensure the movement of organic matter from continents to ocean basins and actively exchange substantial volumes of CO₂ and CH₄ with the atmosphere, thus significantly contributing to Earth's climate regulation. This work presents results of field measurements of greenhouse gas fluxes (CH₄ and CO₂) at the “water - air” interface in the coastal zone of the Ob River (Western Siberia) in summer - autumn 2024 using an original mobile chamber system consisting of a floating chamber and a portable laser gas analyzer Picarro G4301. Gas flux calculations at the “water - air” interface for each measurement used the open-source FluxCalR package in RStudio. The river ecosystem in the area under study acts as a constant source of methane emission into the atmosphere, with the intensity ranging from 0.12 to 15.81 mg × m^-2 × h^-1 (median values). For carbon dioxide, a transition was observed from emission at the beginning of the season (maximal intensity of up to 217.31 mg × m^-2 × h^-1 in July) to sink in August-October. The results confirm the contribution of river systems, particularly of Siberian rivers, to the regional carbon budget and can be used to consider this contribution in climate models.

Air pollution modelling in mountainous regions is a relevant challenge due to the complex interaction of topography with atmospheric dynamics and uncertainty in emission data This paper presents the results of atmospheric pollution modeling for carbon monoxide (CO) in complex mountainous terrain, using the Kislovodsk region as a case study. The study used the mesoscale meteorological model WRF and the chemical transport model CHIMERE. The results were validated against instrumental measurements carried out at the High-Mountain Scientific Station of A.M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences. It is shown that refining the EMEP emission database by incorporating local features of the road network (density and road types) and their daily/weekly dynamics allows the spatial distribution of pollution sources to more closely approximate the actual layout of the region's road network, and also improves the accuracy of reproducing the daily cycle of CO concentrations. An experiment was conducted to quantitatively assess the contribution of orographic factors to the overall pollution level. It was established that the complex terrain of the region accounts for 20-50% of the average CO concentration level, creating zones of pollutant accumulation and dispersion. Statistical analysis demonstrates satisfactory agreement between the modeling results and observational data. The study confirms the feasibility and effectiveness of the WRF-CHIMERE modeling system in monitoring and analyzing atmospheric air quality in resort regions with complex topography. The results can serve a foundation for fundamental and applied scientific research aimed at studying the mechanisms behind the formation of periods with adverse environmental conditions. The air quality modeling can be used by local government authorities for such tasks as urban planning, optimization of road networks, and the development of recreational areas taking into account orographic conditions, as well as for improving regional environmental monitoring systems.

Harmful algal blooms pose a serious threat to the ecology of coastal waters. Their timely detection is a crucial task in environmental monitoring. Optical spectrofluorimetry may be a promising approach in this field. The subject of this scientific work is the study of normalized fluorescence temperature curves (NFTC) as reference features of hazardous microalgae and confirmation of the possibility of identifying the genera of hazardous microalgae under study with their help. NFTC were obtained in laboratory experiments with microalgae monocultures under controlled conditions with registration of fluorescence spectra during linear heating (20-80 °C). Verification was carried out by means of cluster analysis using the principal component analysis (PCA). The study has shown that NFTC demonstrate stable genus-specific patterns, making it possible to distinguish microalgae at the genus level with an accuracy of 90.91%. The use of PCA (3 principal components explaining 94.22% of the variance) eliminates clustering errors caused by multicollinearity of the original features. The highest classification accuracy is achieved for Heterosigma akashiwa (100%), the lowest - for Pseudo-nitzschia (86.15%) due to intrageneric similarity of NFTC. The study shows the need to expand the catalog of standards to enhance the statistical significance of the results.

Effects of heat flux during the early spring plankton vegetation period in Lake Dolgoe (Belarus) were studied based on a coupled mathematical model which reproduces thermohydrodynamic and hydrobiological processes in a freshwater lake. Calculations were performed under different values of heat flux which interacted with the water surface. The simulations showed the following: with increased insolation, which contributed to the intensive spread of inflow waters with a low content of organic matter into the lake, the concentrations of plankton decreased from the surface to some depth, and below that depth they again increased. It was also found that those depths were different for phyto- and zooplankton in the deepest part of the lake (18 m and 15 m, respectively).

This work continues the study of the possibility of using the laser fragmentation/laser-induced fluorescence (LF/LIF) method for the remote detection of nitrocompounds (NC) and organophosphorus compounds (OPC). A method for the combined detection of surface traces of NС and OPС is discussed. It is experimentally shown that exciting laser radiation wavelength of 246.824 nm, falling in the region of overlapping rotational lines of γ(0, 2) and γ(0, 0) bands of NO and PO absorption spectra, can be used for the simultaneous excitation of fluorescence of NС and OPС photofragments. To improve the noise immunity of the LF/LIF detection method, it is proposed to use a wavelength of the probing laser radiation in the range of overlapping γ(0, 2) and γ(1, 1) bands of the absorption spectra of NO- and PO-fragments in excited vibrational states after fragmentation. The resulting intense anti-Stokes γ(0, 1) and γ(1, 0) fluorescence bands are located in the spectral range 235-240 nm and do not overlap with the spectra of broadband Stokes fluorescence of surface materials bearing traces of NС and OPСs. The results can be used in the development of a universal system for the simultaneous detection of surface traces of explosives and toxic substances by LF/LIF method.

Solar-induced fluorescence is an indicator of plant photosynthetic activity that shows promise for monitoring ecosystem productivity on a global scale. The paper presents estimates of the photosynthetic activity for the main phytocenoses of southern Western Siberia (grasslands, deciduous and light coniferous forests, croplands and wetlands) based on TROPOMI satellite data for the period 2018-2024. Using ERA5-Land reanalysis data and products obtained from MODIS and CERES sensor measurements, we investigated the correlations between solar-induced fluorescence and key environmental temperature and moisture parameters, vegetation indices, and photosynthetically active radiation, as well as directly between these features themselves (spatial resolution - 0.05°, temporal resolution - 1 month). The presented results describe the specifics of these relationships both for the main phytocenoses of the entire target region and their latitudinal variability for grasslands and deciduous forests.