Home – Home – Jornals – Atmospheric and Oceanic Optics 2012 number 12

Large array of simultaneous measurements of spectral aerosol extinction coefficients b(l) (surface layer) and the aerosol optical thickness t ^а(l) of the atmosphere in the range l = 0,45¸3,9 μm is analyzed. In many cases, situations revealed, where the height of the homogeneous aerosol atmosphere Н ₀(l) = t ^а(l)/b(l) increases with increasing wavelength in the infrared region of the spectrum. It is suggested that such anomalous spectral dependence of the H ₀(l) is associated with the presence in the boundary layer of clear atmosphere of the visually indistinguishable coarse aerosol of different nature (soil or liquid-drop). It is shown that for detection of such aerosol in the cloud-free atmosphere it is necessary to perform simultaneous measurement of b(l) and t ^а(l) at wavelength l > 2 μm.

Transient response in the near-field scattering of a laser pulse on a micron-sized spherical dielectric particle is considered. The spatial area constituting the photonic jet is theoretically investigated and the analysis of the temporal dynamics of jet dimensions as well as of its peak intensity is presented. The jet evolution scenario is shown to include generally the non-resonant and resonant temporal phases; during each phase the photonic jet can change its spatial form and intensity.

The results of experimenatl study of drop movement and breakdown in a skirling viscous flow at small Reynolds numbers are presented. For the first time it is shown that at small Reynolds numbers the drop breakdown is observed at some critical Bond number values. The dependence of the critical Bond number value corresponding to drop shape instability by Rayleigh–Teylor mechanism from drop movement regime at Reynolds numbers Re = 0.03 ¸ 0.84 is experimentally found.

We derive the Mueller matrix for the molecular scattering of light. Conclusion is based on the concept of independence of the density and anisotropy fluctuations in gases at low pressures and averaging over equiprobable orientations of molecules. A comparison with some of the published matrices is made.

Light scattering matrices of truncated plate-like ice droxtals are calculated within the framework of geometric optics for the case of quasi-horizontal orientations. New halos appear because of truncated facets of ice crystal. The main quantitative properties of the brightest halos are obtained. All 16 elements of the scattering matrix are analyzed in terms of modified scattering matrix. A comparison of the matrices for the truncated droxtals and the hexagonal plates is carried out.

The analysis of vertical distribution of greenhouse gases is carried out according to measurements of authors and to references. Comparison of the received results with most frequently used models is carried out. It is shown, that models are substantially outdated and require a new development.

Using aerosol optical depth (AOD) and active fire (FIRMS) data obtained with the help of MODIS instruments (both Aqua and Terra satellites) and the upper-air network data we present an analysis of spatial-temporal evolution of smoke plume during the period of the mass wildfires over the territory of European Russia (ER) in summer 2010. The relationship between the structural features of the plume with the large-scale dynamics is established. The smoke plume evolution in the metropolitan area is described in detail. Various statistical characteristics of AOD spatial and temporal variations are calculated. An estimation of the mass of smoke is presented. The radiation effects of smoke aerosols are evaluated. The time evolution of the regionally averaged aerosol radiative forcing on the top and the bottom of the atmosphere is described. Spatial distribution of radiative effects over the territory of ER in the period of extreme smoke pollution is presented. A statistically significant correlation between the active fire data and the wind is found. During wildfires period the validation of the AOT obtained by MODIS instrument with the AOD obtained by the CIMEL sun photometer, operated at the AERONET station Zvenigorod, was performed.

Results of the analysis of spatial-temporal distribution of atmospheric total moisture ( W ) and total ozone over Western Siberia, Eastern Siberia, Primorye, and Japanese sea are presented. The evaluation of total moisture was made, using data of radiosonde and satellite measurements. Satellite measurements agree satisfactorily in summer; in winter they disagree more then by two orders of magnitude.

The factors influencing on rainfall production in the Selenge River basin are investigated, using observational data about atmospheric precipitation, surface air temperature, and NCEP/NCAR Reanalysis 1 data about vertical velocity and precipitable water vapor. The contribution of each of rainfall forming factors and relationships between them are defined. Combinations of the most favorable and unfavorable factors for precipitation in the investigated region are revealed. The long-time variations of the total rainfall and rainfall forming factors are investigated for period 1948–2010 in the Selenge River basin. The intervals with different rainfall forming conditions are showed. It was found that the main reason of precipitation decrease observed in recent decades is the atmospheric moisture content decrease caused by reduction in East Asian of the summer monsoon moisture transport.

Results of joint ground-based measurements of vertical structures of ozone and temperatures with the use microwave and lidar technical equipment are presented. The importance of similar observations in the studying of the influence of various disturbances on ozone layer is discussed. The comparative analysis of the received results with satellite MLS/AURA data and with model profiles are given.

The results of bimorph deformable mirror DM2-100-31 testing in AOS at BSVT are described. It is shown that the tip – tilt range of the controllable mirror is not enough for image stabilization in condition of strong wind swinging of telescope construction components. Slow response and insufficient range of controllable mirror surface deformation within clear aperture 60 mm does not allow a high performance of wave front correction.

The results of the laboratory experiments on compensation of the laser beam initial wave front aberrations by the stochastic parallel gradient descent algorithm (SPGDA) are presented. It is shown that for wave front aberration, considered in the experiment, optimal choice of the initial and iteration algorithm steps, as well as the optimal coefficient of noise threshold provides for the compensation of the main part of aberrations, using 150–200 iterations of SPGDA.

Low frequency lasing mode of CuBr laser operation (50 Hz) is made, using double-discharge excitation. Dissociating and main pumping pulses are applied to the active medium. The main feature of the utilized excitation circuit is application of thyristor–based pulser for dissociating pulse forming. Dependences of lasing energy on the dissociative and pumping pulse parameters are studied.

The SP-9 and SPM multiwavelength sun photometers are described and briefly characterized. The SP-9 sun photometer is designed for year-round monitoring of the spectral atmospheric transparency in the wavelength range 0.3–2.2 mm in the regional network of stations. To implement the automatic measurement mode (unattended by operators), the instrument includes solar sensor, automatic sun pointing/tracking system, built-in GPS receiver and flash drive, and sensors of meteorological parameters. The SPМ portable photometer is a simplified version of SP-9 and is designed for the atmospheric transparency measurements under mobile conditions.

200 probability density values ​​of the received radiation of diverging laser beam from the He–Ne laser (l = 0,63 mm), extending to a length of routes of 260 and 520 m at three receiver diameters (0,1, 0,8, and 3,1 mm) are analyzed. Measurements were carried out during the snowfall. It was found that the most commonly measured distributions are approximated by gamma-distribution for all diameters of the receiver. The increase of the receiver’s diameter by 30 times causes the decrease of fluctuations and a change of symmetry when varying the optical thickness along the path.