Home – Home – Jornals – Atmospheric and Oceanic Optics 2021 number 4

High-order Rayleigh-Schrodinger perturbation theory and series summation by the Pade-Hermit approximants are used to calculate the vibrational energy levels of isotopically substituted molecules. As an example, the levels of water isotopologues are calculated. It is found that the perturbation series diverge in the cases of both hydrogen by deuterium or tritium substitution and "heavy" oxygen atom (O¹⁶->O¹⁸) substitution. However, the use of the Pade-Hermit approximants makes it possible to calculate the isotopic level shifts quite accurately for any isotope substitution, both preserving the symmetry of the molecule and reducing it.

The parameters of a nonpolynomial analytical model γ (sur) are determined from the fitting of the known experimental data on the N₂-, O₂-, air-, and self-broadening coefficients of the ozone absorption lines. The model gives a finite value for the coefficients γ in asymptotic. The average accuracy of experimental data description is better than 3% for several thousand lines with quantum numbers up to J = 60. The results of the calculations based on the model suggested are compared to the results obtained using polynomial representations for the broadening coefficients.

Adaptive optics (AO) systems are an essential part of large astronomical telescopes and laser complex operating through the atmosphere. Each AO system is individually designed; the requirements for the elements and the capabilities of an AO system are determined by the intensity and distribution of turbulent fluctuations of the air refractive index over the radiation propagation path. In this paper, we overview the techniques and means for measuring and forecasting atmospheric conditions for AO problems, including those developed at IAO SB RAS. The basic principles of atmospheric adaptive optics and the atmospheric parameters used are briefly described. Particular attention is paid to the parameter introduced for estimating usability of AO systems, i.e., the wind speed at a level of 200 hPa; the comparison with the data from foreign astronomical observatories is carried out. The need in atmospheric research for large Russian astronomical observatories is discussed.

The technique and results of a complex experiment on studying the effect of high-level clouds (HLCs) on the scattered solar radiation flux are described. The optical characteristics (scattering ratio, optical depth, and backscattering phase matrix) and geometric characteristics (the lower and upper boundary altitudes and vertical thickness) of clouds were estimated based on the lidar data, and the scattered solar radiation flux in the zenith direction was measured with a pyranometer. It is shown that specular HLCs, i.e., consisting of preferably horizontally oriented ice crystals, significantly reduce the fluxes of scattered solar radiation incident on the Earth’s surface in comparison with HLCs with approximately the same optical depth, but with chaotically orientated particles.

We present the time series of the total ozone content and integrated aerosol backscattering coefficient in the stratosphere obtained at Siberian Lidar Station in Tomsk. Annual harmonics are distinctly manifested in the frequency spectra of energies of these time series, as well as the semiannual component in ozone time series. Representation of the frequency spectra of both stratospheric constituents on a logarithmic scale made it possible to identify in these spectra the intervals, characteristic for turbulent motion and, hence, cascade energy transfer from larger to smaller eddies and, in particular, in the energy spectrum of the total ozone content. However, the slope of the linear interval is not -1.67, as it would in obedience to the Kolmogorov-Obukhov law, but smaller (-1.22), indicating the presence of an additional energy source which contributes to the frequency variations in the total ozone content.

A broadband model for simulation of the transfer of shortwave solar radiation in the Earth’s atmosphere for spectral channels of radiometers placed in Sentinel-2A satellites is developed. This model is based on line - by - line calculations of absorption spectra with use of modern spectroscopic information and following parameterization of the transmission functions of radiation in the form of short exponent series, which allows one to apply standard method of discrete ordinates to solution of the radiative transfer equation for each exponential component. The errors in the spectral brightness coefficients of the surface due to uncertainties of aerosol extinction in Sentinel-2A channels are estimated for typical optical-meteorological conditions of the lower Volga region.

The review provides information on ozone concentration in the surface air layer in the second half of 2020. Data were obtained at 13 stations located in different regions of Russia. An assessment was made of the excess of hygienic standards established in the Russian Federation, both in the second half of the year and in the whole 2020. It is shown that the daily average maximum permissible concentration of ozone is regularly exceeded at all stations. There are cases of exceeding the one-time maximal maximum permissible concentration.

The vibrational and rotational terms of the X²Π and A²∑⁺ electronic states of the PO molecule have been calculated, as well as the absorption spectrum corresponding to the transition A²∑⁺(ν'=0;J')-X²Π(ν"=0;J") is calculated. The efficiency of laser excitation of PO molecules is estimated as a function of the spectral parameters of the radiation.