Home – Home – Jornals – Atmospheric and Oceanic Optics 2025 number 3

The development of mineral resources of the world ocean puts forward the task of using high-speed communication channels between two underwater objects. Optical radiation provides the highest transmission speed. However, the turbidity of natural water systems varies in a wide range. Therefore, it is relevant to study the influence of various components of water suspension on the conditions of laser pulse transmission. The paper presents the results of simulation of the propagation of optical pulses at a wavelength of 0.514 mm with a duration of 2 ns in water containing only clusters of nanobubbles. It is shown that the maximum flux of radiation scattered on clusters of nanobubbles at the entrance to the receiver does not exceed 10% of the radiation flux that passed without scattering along a path up to 150 m long. At the same time, an increase in pulse width at half-height does not exceed 30%. The limitation of the path length in water containing only clusters of nanobubbles is due to attenuation. Further studies are related to the investigation of the influence of organic and inorganic suspended matter on the propagation of laser radiation in water.

Results of calculations of line widths of 18 water vapor microwave lines broadened by N₂, O₂, CO₂, air, H₂O, CO₂, He, Ar, Kr, and Xe in the temperature range 30 ≤ T ≤ 400 K are presented. In the case of the broadening H₂O lines by monatomic gases, these results strongly depend on the chosen interaction potential; for T ≤ 100 K, they depend on the model of trajectories of colliding molecules. The comparison with experimental data and other calculations is given. The results can be useful for spectral calculations required by atmospheric applications.

The causes of dense non-photochemical haze (smog) over Beijing in winter conditions are still poorly understood. The purpose of the work is to study the mechanism of catalytic oxidation of sulfur dioxide with molecular oxygen in aerosol particles and the formation of dense non-photochemical haze. It is shown that the rapid accumulation of SO₄^2- (tens of μg × m^-3 × h^-1) is observed only at high humidity and moisture acidity in particles рН = 3.7÷4.8. The reason is the transition in these conditions of the catalytic (non-photochemical) oxidation of SO₂ by atmospheric oxygen with the participation of Fe and Mn ions into a fast degenerate branched mode. Modeling of the occurrence of catastrophically dangerous atmospheric haze should necessarily be carried out taking into account the mechanism of this catalytic reaction.

The first results of studies of the elemental composition of atmospheric aerosol and soils of Northern Tajikistan by the method of inductively coupled plasma mass spectrometry (ICP-MS) made it possible to identify high values of substances in some samples. A brief overview of the main directions and results of the study of the content of substances in the composition of aerosol particles and soils in the territory of Northern Tajikistan for the period 2020-2022 is given. Enrichment factors for heavy metals and arsenic in aerosol particles are calculated. The main source of aerosol pollution in the Northern Tajikistan are emissions from the construction industry, motor vehicles, and human economic activity. Heavy metals and arsenic contained in man-made particles are transported by air currents over longer distances.

The features of the intra-day dynamics of fractionation of aerosol particles in surface air during the formation of a winter aerosol field above the Fonovaya observatory of Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, (Tomsk Region) are studied. The distributions of hourly average count concentrations of aerosol particles are analyzed along with the spatial distributions of the probability of transport of moisture-bearing air masses taking into account the time intervals of snow accumulation at the observatory in the first half of winter 2022/23 (from November 17, 2022, to January 30, 2023). It was found that intra-day variations in hourly average count concentrations of aerosol particles in the size range d = 0.3-2.0 mm in some cases are determined by the action of radiometric forces - “snow" photophoresis, caused by and associated with the manifestation of the microphysical properties of aerosol in the field of infrared radiation outgoing from the snow cover. It is reasonably assumed that “snow” photophoresis certainly affects the radiation balance of the winter atmosphere and should be taken into account when modeling vertical transport of aerosols in the lower troposphere.

Filamentation of high-power femtosecond pulses in a gas is of great theoretical and practical interest with relation to study of large-scale spectral and temporal transformations of laser radiation in a medium and generation of extra-wide (supercontinuum) radiation, actual for the problems of nonlinear femtosecond diagnostics of the environment, transmission of optical information through an atmospheric channel, and modern optical technologies for material processing. This paper experimentally studies the influence of pressure of a gas medium (nitrogen) in an optical cell on the characteristics of femtosecond laser radiation propagating under filamentation conditions. It is shown that under conditions of high nitrogen pressure (up to 11 atm) and sharp geometric focusing of femtosecond radiation, its Kerr self-focusing is implemented, and the single filamentation made transforms into multiple post filamentation as the gas pressure increases. In this case, due to the phase self-modulation of a femtosecond pulse and plasma generation in the gas, there is a significant enrichment of the spectral composition of the radiation, and near-linear increase in the pulse spectrum width with gas pressure in the cell. It was established for the first time that the pulse spectrum is extended asymmetrically and mainly to the long-wave region with an increase in the sharpness of the initial focusing of a laser beam. In addition, the average size of intense light post-filaments formed inside a beam decreases and can be fractions of a millimeter as the gas pressure increases in the optical cell.

It is well known that the surface temperature in large cities differs from that of the surrounding area. However, the influence of geometric characteristics of urban areas on the spatial distribution of land surface temperature is poorly studied. This paper, which aimed at solving a scientific problem in the field of urban climatology, presents the results of the analysis of the land surface temperature in four Russian cities with millions of inhabitants performed using Landsat 8 satellite data on cloudless days from May to September 2013-2022. First, the robustness of the urban temperature distribution to relatively weak changes in meteorological conditions is studied. Second, morphological characteristics such as building density, building height, and elevation of terrain were considered as factors that have potential influence on urban surface temperature distribution. The results of the analysis have shown the stability of the temperature field to meteorological conditions, as well as a high correlation between temperature and building density for cities with low-hilly and hilly surface relief. For Krasnoyarsk, characterized by a high degree of heterogeneity of terrain relief, such regularities are not revealed. It is shown that the factor of local temperature growth deserves attention when designing residential areas in large cities with relatively flat relief. The results can provide an opportunity to improve the quality of climate services and the quality of life of the population in urbanized regions.

The article presents an approach to estimating and adjusting the emission power of anthropogenic sources based on forward and inverse modeling. The WRF-Chem model was used as a direct modeling tool, and the IMDAF system developed by the authors was used for inverse modeling. The results of direct modeling provided data on meteorological fields and the distribution of impurities necessary for solving adjoint problems. The use of the adjoint problem method made it possible to calculate a correction factor that determines how much it is necessary to change the power of sources that fall into the sensitivity zone to achieve the best agreement with measurements.

An original method is proposed for calculating turbulent parameters in an atmospheric boundary layer using an unsteady 3D turbulence model and algebraic relations for Reynolds stresses and turbulent heat fluxes. A mesoscale model with such parameterization of turbulence in the boundary layer has been tested on measurements made using meteorological instruments of the Basic Experimental Complex of IAO SB RAS. The daily dynamics of the vertical distribution of some turbulent parameters for the conditions of Tomsk is analyzed. A comparison of calculations with measurements shows that the model well predicts vertical profiles of temperature and horizontal wind speed and direction. However, for conditions where the surface is covered with snow, further research is needed to account the interaction of APS with the surface in the model. The developed turbulence model can be used in calculations of atmospheric boundary layer parameters with high horizontal resolution (grid size 100-1000 m).

Energy characteristics of a copper vapor laser (CVL) pumped by a Marx generator are studied. The schematic of the generator is provided along with the description of its operational features, since thyratrons are used as switches in the generator. It is shown that the Marx generator allows an increase in the upper limit of stable operation of thyratrons (proportional to the number of thyratrons used, up to ~ 8-10 kV of reverse voltage on the thyratron anodes for two thyratrons) and, accordingly, provides pump parameters for the active medium that are unattainable with a single thyratron. At the same time, the energy per pulse linearly increases with the voltage on the gas discharge tube (GDT) and decreases with the repetition rate of the excitation pulses. A CVL pumped by a Marx generator is a promising radiation source for solving problems of atmospheric altitude sensing, creating artificial guide stars in adaptive optics devices and active optical systems, and atmospheric bistatic communication channels.

The paper demonstrates possibility of remote detection of surface traces of organophosphates using the double-pulse laser fragmentation/laser-induced fluorescence (LP/LIF) method. For drop-liquid traces of triethyl phosphate on a paper surface, it is shown that the process of formation of characteristic PO fragments (phosphorus oxide molecules) of organophosphates is inertial. The formation of the maximum concentration of fragments is observed approximately 2 ms after the action of a fragmenting laser pulse (266 nm). It is found that a delay between a laser pulse (247.78 nm) a fragmenting pulse of 2 ms leads to a multiple increase in the fluorescence intensity: approximately 7 times compared to the single-pulse excitation method and approximately 2.3 times compared to simultaneous double-pulse action. The results, first, demonstrate a possibility of remote detection of surface traces of organophosphates in a condensed state by the two-pulse LF/LIF method; second, they show the need to organize optimal conditions for laser exposure to increase the efficiency of the LF/LIF process.