Home – Home – Jornals – Atmospheric and Oceanic Optics 2023 number 7

The comparative analysis of data available from open sources on the water spectral lines intensities in the frequency range from 0 to 1.75 THz has been carried out. The calculations by the method of effective Hamiltonians and the variational method, as well as experimental data were taken into account. It has been established that the intensity uncertainty is less than 2% for lines in the ground vibrational state with an intensity of more than 10^-27 cm/mol. and is about 5-10% for weaker lines. For strong (more than 10^-26 cm/mol.) lines in the ν₂ state, the uncertainty ranges from 2 to 5% and increases to 5-10% for weak lines. For all lines in the 2ν₂, ν₁, and ν₃ states, the uncertainty is no more than 5-10%. The presented data show that most of the considered lines can be assigned a higher (by 1-2 steps according to the classification adopted in HITRAN) category of intensity accuracy.

The form of the vibrational-rotational operator of kinetic energy for linear symmetric molecules of the A₂B₂ type in polyspherical non-orthogonal internal (bond lengths and angles between bonds) coordinates is obtained. Non-orthogonal coordinates have advantages in calculating the wave functions of heavy linear molecules, for example, C₂F₂, C₂Cl_2, and also simplify the calculation of the intensity of the lines of the vibrational-rotational spectra of molecules of this type. This work is a continuation of the previous work [1], in which the form of the kinetic energy operator in orthogonal coordinates was obtained. To verify the obtained expressions, the lower vibrational-rotational energy levels of the acetylene molecule were calculated.

Graphical resources on the continuum absorption of water vapor and its mixtures published in 2011-2020 are described. Summary tables are presented that characterize the main parameters of the absorption coefficients and transmission functions in different spectral intervals, the temperature dependence of the absorption coefficient, and the equilibrium constant of the water dimer formation reaction. The features of the study of the continuum absorption in published works in this time interval are noted. In a concise form, the results of the assessment of the quality of citing plots are presented, which are described by four qualitative and quantitative attributes. Three citation procedures are characterized, two of which are computerized. A method for estimating the difference between the citing and cited plots and examples of pairs "citing and cited plots" with a quantitative assessment of the difference are presented.

This work is a continuation of the paper "Measurements of atmospheric parameters along an extended paths. I. Acoustic measurements of turbulence and average wind speed" and is devoted to the results of optical measurements of atmospheric turbulence along horizontal atmospheric paths. These measurements were carried out to determine the effective mean values of atmospheric turbulence parameters along an optical radiation propagation path and the associated coherence length of optical waves propagating through the atmosphere. The path optical measurements were supported by AMK-03 acoustic weather station measurements. That made it possible to compare the local acoustic and optical measurements of turbulence with different optical meters.

The results of experimental studies of aerosol in the surface air layer in the southeastern part of the Crimean Peninsula at the background environmental monitoring station of the Vyazemsky Karadag scientific station from March 21 to June 17, 2020, are presented. The daily average mass concentration over aerosol for the entire measurement period ranged from 3 to 35 mg/m3, with an average value of 13 mg/m3. The exception was high concentrations of particles during the episode of 25–27.03.2020 (48, 195, and 49 mg/m3), when a extreme eastward transfer from sources in Kazakhstan (a dust storm on the Aral Sea) through Kalmykia to the Crimea took place. Taking into account this episode, the daily average aerosol mass concentration was 16 mg/m3. Days with different directions of air masses arrival, as well as days with the highest daily mean values of aerosol mass concentration were identified out of 89 observation days. For this sample (31 samples), the content of 64 chemical elements was determined in the samples. Accumulation of chemical elements in soil and in aerosol particles was estimated; clarks of chemical element concentrations in soil, aerosol concentration coefficients, and enrichment coefficients of chemical elements in aerosols were calculated. The dependences of the mass concentration and disperse and elemental composition of the surface aerosol on further aerosol migration are considered.

Water vapour plays a key role in different climate-forming processes at various altitudes of the Earth's atmosphere. Water vapour isotopologues monitoring provides information on the atmospheric hydrological cycle. It helps to study the processes associated with evaporation and condensation that control the humidity in the troposphere and water exchange between the troposphere and stratosphere. For the first time, temporal variability of water vapor isotopologues (H₂O and δD) in Peterhof in 2009-2020 were analyzed using ground-based measurements of solar IR radiation by the Bruker IFS 125HR Fourier spectrometer. For both H₂O and δD, the maximum values occur in summer, the minimum - in winter, while the largest variability of H₂O is observed in summer, and δD - in winter months due to the climatic features of St. Petersburg, i.e. the origin and history of incoming air masses. The database of water vapour isotopic composition in the vicinity of St. Petersburg can be used in models of the general circulation of the atmosphere to improve the accuracy of weather forecasting and long-term changes in the regional climate.

The results are presented of laboratory experiments to determine the characteristics of convective turbulence over a heated metal surface for various heights and temperatures by high-speed thermography. The study of convective turbulence characteristics was carried out using a high-speed infrared camera by shooting the temperature field of low-inertia paper targets suspended above the heated surface simultaneously over the entire vertical plane of the IR camera field of view. Based on fluctuations in the temperature field of the target surface, the heat transfer coefficient, the intensity level of the convective flow, the total flow, and the amount of heat generated during measurements at different heights above the surface are determined. The energy spectra of convective turbulence are plotted under various turbulent conditions. An analysis of the turbulence spectra showed the presence of an inertial interval with a slope close to the 8/3 power law for all considered heights above the heated surface, temperatures, and turbulence conditions. Characteristics of convective turbulence obtained can be used when testing various optical adaptive laser beam control systems, studying the propagation of vortex laser beams and combustion centers, which are also characterized by convective turbulence with a further transition to atmospheric turbulence induced by combustion energy.

Lidar is an important tool for studying atmospheric aerosol; it is widely used in studying the propagation of aerosol pollution in the atmosphere. During environmental monitoring, especially with a mobile lidar, it is important not only to detect a pollutant, but also to determine the spatial coordinates of its source and the propagation dynamics. In the work, we suggest a technique for calculating the coordinates of an object under study from the lidar coordinates, sensing direction, and the distance between the lidar and the object. The software implementation of the technique and an example of its application in the design of an auxiliary lidar system are described.

Changes in the oxygen (δ¹⁸O) and hydrogen (δD) isotope compositions of precipitation in Tomsk in the period from 2016 to 2020 are studied. It is found that the δ¹⁸O value varies in the range from -39.6 to +2.1‰, the average value over the entire period is -18 ± 6.8‰; the δD value varies in the range from -299 to -4.9‰, the average value is -118.7 ± 54.7‰. A Local Meteoric Water Line is calculated for the period from 2016 to 2020: δD = 7.43δ¹⁸O + 11.2; this equation indicates the predominance of evaporative fractionation. The dependence of the isotope composition of precipitation on temperature in Tomsk is derived: +0.47‰/°C for the δ¹⁸O value and +3.62‰/°C for the δD value. The main regions that provide atmospheric precipitation with different isotope compositions to Tomsk are identified based on the analysis of the airmass backward trajectories.

Gases desorbed by the vacuum method from the tree rings of discs of deciduous trees are measured. The content of residual gases vacuum-desorbed from tree rings is analyzed with an opto-acoustic gas analyzer with a tunable CO₂ laser. The chronologies of residual CO₂ and (CO₂ + H₂O) of some deciduous trees growing near the city of Tomsk (West Siberia) have been derived. All the chronologies are cyclic with pronounced 2-4-year cycles. A correlation was found between the content of gases and summer temperatures and precipitation. We believe that the annual distribution of residual gases in the discs reflects the pattern of annual release of the gases from the stems of the deciduous trees into the atmosphere.