Home – Home – Jornals – Atmospheric and Oceanic Optics 2023 number 4

The spectrum of the ¹⁵N¹⁶O molecule in the region 5200-5500 сm^-1 is recorded and analyzed. As a result of the analysis, 150 Λ-doublets of vibration-rotational lines are found in the 3-0 band of the main transitions between the ²Π_1/2 and ²Π_3/2 electronic states. For 108 of them, when the splitting value was greater than 4.5 × 10^-13 сm^-1, it was possible to obtain the positions and relative intensities of each component of the doublet, while the self-expansion parameter was fixed to the value from HITRAN2020, and the intensities of the components e and f were considered equal. The maximum of the rotational quantum number J was 30.5. The frequencies of the transitions recorded, weighted in accordance with the experimental uncertainties, were processed by the program code using the non-linear least squares method. As a result of processing, the spectroscopic constants for the v = 3 vibrational state of the ¹⁵N¹⁶O isotopologue are found. The Λ-doubling constants for this state are determined for the first time. The results are compared with the well-known database of spectroscopic information HITRAN2020.

Today, the gas-adsorption porosimetry technique is standard for determining the pore sizes of nanoporous materials. However, it requires liquid nitrogen, and measurements take a long time. We have suggested a spectroscopic technique for determining the pore diameters of nanoporous silicon materials from the absorption spectra of water adsorbed in a material (Atmos. Ocean. Opt. 2021. V. 34, N 6. P. 542-546). In this work, this technique is used to measure the pore size of zeolites. The pore sizes of five samples are estimated with the use of the regression analysis. The values obtained by the spectroscopic technique are in a good agreement with measurements by the standard one: the error of the spectroscopic technique is less than 10%. In terms of speed, the spectroscopic technique exceeds the standard one by dozens of times. The spectroscopic technique can also be applied to determining the static water capacity of materials.

The results obtained at Institute of Atmospheric Optics SB RAS and abroad in studying the broadening and shifts of H₂O absorption lines by monatomic gases He, Ar, Kr, and Xe are reviewed. The experimental studies at IAO SB RAS were carried out in the spectral range 3200-11200 cm^-1 using a Bruker IFS 125 Fourier spectrometer. The broadening and shift coefficients were measured for the lines of 24 vibrational bands with maxim of vibrational quantum numbers v₁ = 3, v₂ = 6, and v₃ = 3 and of rotational quantum numbers J = 14 and K_a = 8. The calculations were carried out by the semiclassical method using effective vibrationally dependent potentials. The experimental and calculated values of the broadening and shift coefficients are compared. Using the analytical model γ(sur), available experimental data on the broadening coefficients are analyzed, and their incompatibility is revealed in some cases. The model parameters γ(sur) are determined which allow generating the coefficients of broadening of H₂O absorption lines by He, Ar, Kr, and Xe atoms in the range 350-14000 cm^-1.

The work analyzes the spatial distribution of carbon dioxide over the seas of the Russian sector of the Arctic based on the results of the comprehensive experiment conducted in September 2020. It turned out that during the experiment, the concentration of CO₂ increased from west to east. The minimum 396 ppm was over the Barents Sea, and the maximum, over the Chukchi Sea - 4106 ppm. The difference in concentrations between a level of 200 m and the free troposphere reached -156 ppm over the Barents Sea and decreased to -56 ppm over the Laptev Sea. Over the eastern seas, the difference generally became positive, which was associated with the air transfer from Alaska. Above the waters of most seas, horizontal heterogeneity in the distribution of carbon dioxide was observed, reflecting the regional features of its assimilation by the ocean and transfer from the continent.

Carbon monoxide (CO) total column (TC) measurements of the TROPOMI high-resolution orbital spectrometer have been validated by ground-based spectroscopic measurements at sites of the A.M. Obukhov Institute of Atmoshperic Physics, Russian Academy of Sciences, in Moscow and Zvenigorod for the period from June 28, 2018, to December 31, 2021. Correlation coefficients ( R ) between TROPOMI orbital data and ground-based stationary data are determined and analyzed. The high values of the correlation coefficient are obtained ( R ~ 0.81-0.97) depending on the observation point, spatial averaging, and filtration applied. For different averaging of satellite data, the dependences of correlation parameters on the orbital angles, underlying surface albedo, and the height of atmospheric boundary layer are investigated. No influence of albedo on the correlation parameters of orbital and ground-based measurements is found for both observation sites. No significant dependence of correlation parameters on the viewing zenith angle is detected either. However, the correlation coefficients depend on the viewing azimuthal angles and the height of the atmospheric boundary layer. An increase in the correlation is obtained during observations at viewing azimuthal angles of less than 40° (up to R ~ 0.97), as well as under an increase in the height of the atmospheric boundary layer (up to R ~ 0.90).

The snow cover pollution in Kyzyl in 2013-2021 is analyzed based on remote sensing data. Software scripts are created in the GEE software environment; NDSI, S3, and SCI indices are calculated. Maps of the annual average value of NDSI are constructed; the degree of contamination of the territory is determined. It is found that the areas with NDSI < 0.3 weakly changed in 2013-2021: it was minimal in 2015 and 2017 and maximal (0.68%) in 2018. The NDSI values from 0.3 to 0.45 (more than 64% of the total territory under study) prevailed from 2014 to 2017.

Quantitative estimates of regional features of the frequency distribution of extreme temperature, precipitation, and wind anomalies in the winter months in the extratropical zone of the Northern Hemisphere associated with atmospheric circulation regimes in the Euro-Atlantic sector are obtained. Using the k-means cluster analysis for the daily geopotential height fields from the ERA5 reanalysis for 1979-2021 four winter atmospheric circulation regimes are identified in the Euro-Atlantic sector corresponding to the North Atlantic Oscillation (NAO) in the positive (NAO+) and negative (NAO-) phases, Scandinavian blocking (SCAND), and regime with anomalously high pressure over the North Atlantic and low pressure over Europe (ATL). Characteristic fields and frequencies of occurrence of the regimes are analyzed. The NAO+ and NAO- regimes turned out to be asymmetric in the spatial structure with significantly different frequencies of occurrence (33% and 19%, respectively). Spatial distributions of the frequencies of occurrence of extreme weather anomalies associated with the regimes are also asymmetric. For all regimes, an asymmetric frequency of occurrence of positive and negative temperature anomalies is noted. During the period under study, no statistically significant trends in the seasonal frequency of the regimes and no large areas with statistically significant trends in the average seasonal fields of the regimes near the areas of geopotential height anomalies maxima are found, which can indicate the stability of these regimes under recent climate changes.

A method is suggested for classifying weather forecast ensemble members and identifying the set of the ensemble members which most likely reflects the future state of the atmosphere. The first forecast month of the ensemble is used for the comparison between every selected class and observation data in order to identify the most realistic scenario of the development of atmospheric processes. The best class is used for prediction of the sea level pressure and surface temperature anomaly fields for the next month. The method suggested allows improving the quality of forecasts for north-west of the Russian Federation and the Arctic.

The mechanisms of the formation of ozone mini-holes (OMHs) and their influence on the levels of UV radiation (UVR) over May 22-24, 2021, in the middle and southern parts of the Volga region and the south of the Urals and Western Siberia and over March 16-18, 2022, in the northwest of the European of Russia are studied using data from the AIRS satellite infrared spectrometer and NCEP reanalysis. It is shown that the formation of these OMHs is due to the increase in the tropopause level associated with the anticyclone and the transfer of low-ozone air masses from the subtropics. In the first period of the OMH, negative total ozone (TO) anomalies were up to ~ 20% of the average values from 2003 to 2021, and positive UVR anomalies attained 40-60%, the UV index increased from ~ 6 to ~ 8. In the second period, in the region of the OMH with negative TO anomalies up to ~ -40%, positive UVR anomalies attained 40-60%, and the UV index increased from ~ 1 to ~ 2. Calculations with an original spectral model, which allows solving the transport equation at a single point, confirmed the increase in UVR revealed in satellite observations in the OMH regions.

The efficiency of monostatic and bistatic schemes of the formation of a laser guide staris is analyzed on the basis of the correlation theory of Gaussian random processes. In the focal plane of a ground-based optical telescope, the position of a natural star relative to the measured instantaneous position of a laser guide star is calculated based on Pearson's linear regression. An expression is derived for the correlation coefficient of random angular displacements of images of a natural star and a laser guide star. Based on this expression, the normalized dispersion of uncompensated (residual) angular errors is determined. The results of calculations for monostatic and bistatic schemes of the formation of a laser guide star are presented, which make it possible to estimate and compare their efficiency.