Home – Home – Jornals – Atmospheric and Oceanic Optics 2024 number 11

The article is devoted to the problem of automation of fitting lines parameters in high-resolution spectra recorded at modern spectrometers. When fitting a model contour, due to the presence of many local minima in the minimized standard deviation, a sufficiently accurate initial approximation of line profile parameters is required. The article proposes a method for finding a sufficiently accurate initial approximation of line profile parameters for the convergence of the fitting process. The method is based on the Kohonen neural network. Tests and comparison of other algorithms and networks for solving this problem are carried out. The suggested method can be used to process vibrational-rotational spectra and obtain databases for solving problems of atmospheric optics, molecular physics, and engineering problems.

The article describes part of the collection of plots “Continuous absorption of a carbon dioxide molecule” of the GrafOnto information system (IS) extracted from publications of 1991-2000. The thermodynamic conditions under which measurements and calculations were carried out are given, physical quantities and their dimensions are indicated, as well as the spectral and temperature intervals under study. The progress in solving continuum absorption problems in the specified period of time is briefly described. The expansion of the functionality of the GrafOnto IS is described. The extension addressed the problem of plots in a collection, which can be separated into families of similar plots contained in clusters of plots formed in transparency windows. The selection of families allows you to use not only individual plots in the analysis, but also their sets, the composition of which is determined by spectral or temperature quantities. A family of similar plots has been added to the properties (metadata) of primitive plots. The quantitative assessment of the proximity of plots has been introduced.

A formula has been derived which connects the structural constant of temperature fluctuations with the dissipation rate of the kinetic energy of turbulence not through the turbulent thermal diffusivity, but through the vertical gradients of average wind speed and air temperature and the turbulent Prandtl number. To estimate the structural characteristics of temperature using this formula, we suggest a model based on the generalization of known data on the turbulent Prandtl number as a function of the gradient Richardson number. It has been experimentally shown that the time series of the structural constant of temperature, which is calculated using the proposed formula and independently found from the spectra of temperature fluctuations based on measurements of wind speed and air temperature with sonic anemometers at two altitudes, are consistent with each other. This confirms the correctness of the theoretical constructions, which serve the basic for the model dependence of the turbulent Prandtl number on the gradient Richardson number.

Air pollution is a serious danger not only to human health, but also to the environment. The study of the carbon isotope composition of atmospheric aerosol in cities is of particular interest and has great potential for determining the dominant sources of aerosol particles. The results of continuous monitoring of the isotopic composition of total carbon (d¹³C) in atmospheric aerosol (with a resolution of 3 days) during the winter-spring season (November 2020 - May 2021) in Tomsk are presented. The d¹³С value ranged from -29.4 to -24.7‰, with the carbon percentage ranging from 1.3 to 35%. For 67 samples of carbonaceous atmospheric aerosol, the mean d¹³С value was -26.2 ± 0.3‰. The average d¹³С values of aerosol were -25.9 ± 0.5‰ in winter and -26.5 ± 1‰ in spring. The widest scatter of d¹³С values was observed during the spring, which indicates the presence of various sources of origin of carbonaceous aerosol particles. The main sources of carbonaceous aerosol particles were identified through the combined analysis of global map of wind (earth.nullschool.net), air masses backward trajectories (by NOAA HYSPLIT model), wind rose, and data on the variability of d¹³C values. In winter, the dominant source of carbonaceous aerosol was the city thermal power plant GRES-2. The study results not only contribute to understanding the sources of origin and transformation processes of atmospheric aerosols in Tomsk, but also can be input parameters for modeling the transport of aerosol particles on the regional scale.

Liquid-drop clouds play a significant role in the evolution of cloud systems and the formation of the Earth’s radiation balance. Determination of their optical and microphysical characteristics is one of the most important problems of optics and atmospheric physics. The paper is devoted to assessing the applicability of an artificial neural network to processing synthetic data of passive satellite measurements of reflected solar radiation of low and medium spatial resolution in the visible and short-wave infrared spectral regions in order to simultaneously retrieve the optical thickness and effective radius of droplets of horizontally inhomogeneous cloudiness. The network is trained using the Monte Carlo calculated values of radiance in marine stratocumulus clouds generated by a fractal model. Through a nonlinear approximation of the dependence of optical and microphysical parameters of clouds on radiation characteristics, the tested algorithm allows taking into account the effects of horizontal radiative transfer, unlike classical IPA/NIPA (Independent Pixel Approximation/Nonlocal Independent Pixel Approximation) schemes. It is shown that the errors in solving the inverse problem can be reduced by assimilating data in adjacent pixels, reducing spatial resolution, and using radiance data received at small solar zenith angles. The high correlation between the test and retrieved optical thickness and effective radius indicate the possibility of using a neural network approach to interpreting satellite measurement data.

The paper considers the methodological features of determining the optical extinction and backscattering coefficients by simultaneous lidar measurements at the following wavelengths: 532 nm (elastic scattering, ES); 607 nm (vibrational-rotational Raman scattering, RS); 530 nm (purely rotational RS). The ES signal identifies the range of allowable values (RAV) of the coefficients based on the a priori introduction of a physically substantiated lidar ratio. The RS signal at 607 nm, corresponding to a single line of the N₂ spectrum, provides a plausible estimate of the ratios in the boundary layer and part of the middle troposphere. The CR signal at 530 nm - a set of N₂ and O₂ spectrum lines - is characterized by smaller errors and provides a quantitative estimate of the coefficients in all main tropospheric layers. At a wavelength of 530 nm, the differential backscattering cross section depends on height due to temperature changes, which leads to a redistribution of N₂ and O₂ line intensities. Estimation of parameters from the RS signals is considered plausible when the sought-after coefficients are quantitatively comparable and, at the same time, located within their RAVs. The algorithms is tested using ground-based sensing data on the shore of Lake Baikal in August 2023.

Atmospheric temperature anomalies associated with sudden stratospheric warmings (SSWs) observed over the territory of Siberia require detailed study. In Siberia, there are few instruments that can provide the necessary information on the vertical distribution of atmospheric temperature. Unique lidar of the Siberian Lidar Station (SLS) of V.E. Zuev Institute of Atmospheric Optics SB RAS, Tomsk, Russia (56.48° N, 85.05° E), developed for regular lidar measurements of atmospheric parameters, is one of few ground-based devices in Siberia which provide necessary data on the vertical stratification of atmospheric temperature during a SSW event. To determine the characteristics of atmospheric temperature anomalies during the SSW period in winter 2023 over Tomsk, data on atmospheric temperature in individual nights obtained by the SLS lidar, the WACCM model, the standard mid-latitude winter model, and the ERA5 reanalysis were compared. For the first time, the possibility of using vertical atmospheric temperature profiles obtained by the Raman scattering method to study the SSW effect is show. Use of lidar air temperature profiles to analyze changes in the vertical structure of the atmosphere during sudden stratospheric warmings is demonstrated.

At present, the relationship between sulfur dioxide (SO₂) concentration and small-scale turbulence within Southern Baikal has been described in a limited volume. The paper presents the results of a study of jet streams and atmospheric turbulence affecting the surface SO₂ content over Listvyanka station. The cases are considered when the surface SO₂ concentration tends to increase at negative vertical turbulent specific heat fluxes. This occurs against the background of the formation of jet streams within the lower layer of the atmosphere and large vertical shears of the wind speed below the jet formation height. The vertical turbulent specific heat flux in the surface layer of the atmosphere can serve as a key indicator determining the possibility of a positive relationship between the surface SO₂ concentration and the total kinetic energy of turbulence. The analysis revealed that the SO₂ concentration tends to increase at negative vertical turbulent temperature fluxes against the background of the development of low-level jet streams. In similar situations, but with positive or close to zero temperature flux values, SO₂ concentrations usually remain at background levels.

The periodicity of synoptic-scale variations in aerosol characteristics in the atmosphere of Eurasian sector of the Arctic Ocean is analyzed on the basic of long-term measurements. Statistically significant maxima of amplitude functions in the range from 3.5 to 18 days were manifested in periodograms of the concentrations of submicron aerosol and black carbon ( V_f and еВС). Cases of anomalously high еВС and V_f (5% of data), associated with long-range transports of continental pollutants, were considered in more detail. It is shown that the average duration of “anomalies” in еВС and V_f is few days, and the maximal duration attains 112 hours. The time intervals between “anomalies” are, on the average, 6-16 days, and the maximal intervals are from 28 to 69 days. Despite the short duration and rare occurrence of anomalous situations, they increase the average concentrations of aerosol and black carbon by 28-77%. Calculations showed that the major (79%) contributors to air pollution over the Kara and Barents Seas are made by the outflows of anthropogenic pollutants; and in the eastern sector of the Arctic Ocean, the contribution of smokes from wildfires is maximal. The effect of the products of associated gas combustion at gas-oil plants was manifested most strongly (up to 51%) in the atmosphere of Cape Baranov.

This work studies the effect of the daily dynamics of turbulent processes on the daily dynamics of the electric field in the surface air layer. When modeling, the coefficient of turbulent diffusion within the electrode layer is specified as a stationary function of altitude in view of hydrodynamic concepts. A mathematical model of the dynamics of the electric field intensity in the surface air layer in the case of a turbulent electrode effect is suggested. The main equation of the model is the equation of the total current in the surface layer, which has been derived in the approximation of strong turbulent mixing and describes the electrodynamics of the surface layer under the combined action of local and global current generators. The work examines the non-stationary nature of turbulent exchange in order to confirm the previously identified effects in the daily dynamics of the electric field strength in the surface layer under stationary turbulence. To describe the daily dynamics of turbulent processes, gradient measurements in high-altitude conditions of the Elbrus region were used. Processing of the measurement data enables deriving the time dependence of the turbulent diffusion coefficient from the solution of the total current equation. Taking into account this dependence, the expression for the daily dynamics of the field strength was refined. Time shifts of the daily extremes, a change in their amplitude, and the appearance of additional extremes depending on the electric field strength have been established. All these effects are comparable to the global unitary variation and increase with the electric field strength. The results can be useful for solving a number of applied geophysical problems, in particular, monitoring the electric field of the atmosphere and analyzing atmospheric-electrical measurement data.

A comprehensive approach to simulation of the fields of dispersion of pollutants in the surface air layer from flare installations on the territory of the Mamontovskoye field of the Nefteyugansk district of the KhMAO is suggested. It includes the simulation of pollutant concentrations (carbon monoxide, nitrogen dioxide, and soot) with the use of UPRZA Eco-Center software based on terrestrial data on the content of organic compounds in soils and satellite data (AIRS) on greenhouse gas concentrations. This approach enables comprehensive studies of the state of the natural environment in remote northern oil and gas producing areas on the basis of satellite and ground-based data.

In recent years, laser sources created in airborne laser plasma by powerful femtosecond radiation pulses have been rapidly developing. This work studies coherent radiation generation on N₂⁺ ions in laser plasma using two-color pumping at λ = 950 and 475 nm. It is shown that the addition of second harmonic radiation, wavelength of which is closer to the lasing lines on ions compared to the first harmonic, increases the intensity and stability of supercontinuum radiation which acts as seed radiation for the lasing. Such pumping allows lasing on new lines and controlling the intensity and spectral composition of the generated radiation. The results can be useful for establishing the way(s) of creating population inversion in laser plasma on molecular nitrogen ions.

The effect of vertical and horizontal turbulent heat fluxes on the air temperature variance under conditions of temperature inversions of different intensity is considered. It is shown that the neglect of horizontal turbulent heat fluxes under these conditions in the existing models can lead to significant underestimation of the mixing layer height.

The XXX Anniversary International Symposium “Atmosphere and Ocean Optics. Atmospheric Physics” was held from July 1 to 5, 2024, in Saint Petersburg (Russia). The Symposium program included 320 reports on priority areas of development of science, technology, and engineering of the Russian Federation, including 4 plenary, 2 invited, 81 oral, 81 poster, and 152 on-line poster reports. Holding such an event at one of the scientific centers of the Russian Academy of Sciences ensures significant representation in the world scientific community of researchers from Russian scientific schools, which are leading in the country and widely known in the world.