Vol 29, No 1 (2016)

We study the annual behavior of the concentration of organic components of the atmospheric aerosol, sampled onboard the Tu-134 Optik airborne laboratory in the atmospheric layer of 500–8500 m. The concentration of the organic component in aerosol composition is found to be maximal during spring and minimal during fall. Compounds ranging from C₈H₁₈ to C₃₅H₇₂ are detected in the composition of aerosol particles. The range of hydrocarbons is the widest during the winter period (C₁₂H₂₆–C₃₅H₇₂) and during spring (C₈H₁₈–C₃₁H₆₄), and it is markedly narrower during summer (C₁₈H₃₈–C₃₃H₆₈) and during fall (C₁₆H₃₄–C₃₁H₆₄). One mode (n-alkane C₂₀H₄₂) predominates in aerosol composition throughout the year. A secondary maximum, corresponding to n-alkane C₂₉H₆₀, appears during the summer period.

A study was conducted on how the upper boundary λ_max of the spectral range in which the transmission of the atmosphere is measured has an effect on results of reconstruction of aerosol microstructure parameters in the process of solving the inverse problem of solar photometry by data from numerical simulation and field experiments. The numerical experiment involves the model of aerosol formed by the submicron (fine) (f) and coarse (c) fractions of particles. The quantity λ_max was chosen in the range from 1.052 to 3.973 μm. To solve the inverse problem, the integral distribution method was used. It is shown that a restriction of the spectrum interval implies an underestimation of the contribution of large particles in the aerosol distribution. In particular, at λ_max = 1.246 μm, on the background of a decrease in the volume concentration of aerosol (up to 18% at λ_max = 1.246 μm), losses in the reconstruction of the concentration of particles from the c-fraction can reach 42%.

The technique for multifrequency diagnostics of a vibrational nonequilibrium gas mixture that contains CO₂ molecules is proposed. The technique uses data on unsaturated gains at lines of the 00⁰1–[10⁰0, 02⁰0]_{I, II} and 00⁰2–[10⁰1, 02⁰1]_{I, II} transitions obtained with the help of a tunable CO₂ laser. Results of the study of the influence of accuracy of gain measurements and the number of sensing lines on errors in determining populations of vibrational levels and gas mixture translational temperatures are presented.

Results of numerical statistical simulation of an experiment on ground-based sensing of the cloud layer by linearly polarized terahertz range radiation at several wavelengths from the transmission windows of the atmosphere are presented. The models of the scattering layer involve liquid droplet size distribution functions pooled by results of long-term field experiments in middle latitudes of the Earth, as well as distribution functions obtained in flight measurements near the coast of Great Britain. The models of the scattering medium take into account the vertical stratification of water vapor in the atmosphere and the difference in the microstructure of the cloud layer near its top and bottom.

The results of a joint study of spatial inhomogeneity and accuracy of retrieving temperature profiles in the atmospheric boundary layer over Moscow are analyzed. Measurements at three sites allowed estimating the spatial variability of thermal stratification in the megalopolis. The effect of local features of the observation sites on the retrieval error at all altitudes is shown. To reduce this effect, the retrieval of temperature lapse rate is suggested. Comparison of temperature gradients showed a gradual decrease in the effect of the local features in the range from 100 to 300 m. Based on the statistical variability analysis of the vertical temperature gradients, a reference mesh of temperature profilers is suggested.

Results of the comparative analysis of observational series of the total ozone content and UV radiation of the 300–315-nm wavelength band at stations located in boreal forest zones of midlatitudes of Russia and Canada (Northern Hemisphere, 50° N and higher) are presented. It is shown that the ozonosphere is a primary modulator of the biologically active part of UV-B radiation in this climatic zone. Radiation amplification factors of solar UV-B spectral region are determined. It is shown that 20% of total ozone depletion increases more than twofold the dose of the short-wave part of solar UV-B radiation relative to its climatic normal.

Variations in the aerosol concentration with periods more than one month are analyzed using measurements of mass concentration of the near-ground aerosol at Zvenigorod Scientific Station of the A.M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences. It is shown that the variations can be associated with the periodic recurrences of atmospheric transport trajectories from certain directions. We considered the cases when long-period variations in aerosol concentration were due to episodes of increased or decreased concentrations caused by aerosol advection from the corresponding directions. In particular, the 1.5-month variations in the aerosol mass concentration in 1995 were found to be due to the 1.5-month recurrences of the concentration maxima caused by southeasterly transport. The three-month periodicity of the transport episodes from directions of Baltic and North Atlantic in 2004 manifested themselves in 3-month recurrence of the aerosol concentration minima. A statistical relation is revealed between the near-ground aerosol concentration and the Arctic upper troposphere dynamics.

To reduce the effect of the time delay on the operation of an adaptive system treated as a dynamic feedback system, the present-day approach to the correction of turbulent distortions of optical radiation supposes application of new control algorithms for the correcting mirror on the basis of forecasting phase distortions. Results of the numerical simulation are presented.

Metrological support of production and exploitation of ultrasonic thermoanemometers (anemometers/thermometers) (UTA) for measurement of meteorological parameters of the atmospheric boundary layer is considered in this work. Necessary UTA tests are described: in an wind tunnel, zero wind chamber, climatic chamber, and in a pressure chamber. Parameters of the ADS-60 wind tunnel, which has been designed at Institute of Monitoring of Climatic and Ecological Systems, Siberian Branch, Russian Academy of Sciences, are given. ADS-60 was designed for testing UTA against rules of Russian Federal Service for Hydrometeorology and Environmental Monitoring for wind velocity. A mobile complex designed for checking technical parameters of UTA in field conditions is described.