Home – Home – Jornals – Atmospheric and Oceanic Optics 2013 number 12

Effect of atmospheric turbulence on power fluctuations of backscattered laser radiation at lidar receiving aperture is estimated. The estimates are obtained for divergent laser beams with the Gaussian intensity distribution in the Rytov approximation. Simple analytic formulas are suggested as estimators of the variance of received power fluctuations. Estimates showed that, for paths of length about 10 km and radii of sounding region about 1 m, root square values of relative power fluctuations can be comparable with relative variation of the received power at changing sounding from atmospheric regions with background turbulence to highly turbulent regions (clear air turbulence).

Results of the atmospheric experiments on adaptive correction of the initial wave front aberrations of laser beams of visible and infrared wave range are present. The measured mean power of the laser beam radiation backscattered by a diffuse screen was used for adaptive control for the flexible mirror. It is shown that the efficiency of mitigation of the initial wave front aberrations increases with decreasing the receiver diaphragm diameter. Data of the experiments agree with the results of the qualitative analysis of efficiency of the used experimental set up for mitigation of the wave front aberrations.

The experimental results on transformation of the spectral and spatial characteristics of femtosecond Ti:Sapphire-laser pulses with the wavelengths of 800 and 400 nm at both harmonics during filamentation in liquid media are presented. It is shown that spectral broadening of a laser pulse at the expense of phase self-modulation in a medium with cubic nonlinearity depends on pulse power and beam diameter. Emission with maximum at 464 nm is observed during filamentation of the pulses with wavelength of 400 nm in distilled water, which corresponds to stimulated Raman scattering of the water. Fluorescence of dissolved organic matters is observed in sea water.

We show that large-scale atmospheric inhomogeneities observed in experiments can significantly affect optical radiation propagation along extended paths. We demonstrate that it is impossible to take into account this effect in the framework of the classical turbulence model. We propose a new algorithm for numerical simulation of laser beam propagation along extended low-inclined atmospheric paths with large-scale atmospheric inhomogeneities, which allows one to take into account beam refraction and focusing on the large-scale inhomogeneities along with beam distortions due to small-scale inhomogeneities and regular refraction in a vertical plane.

A methodology for measuring the astronomic climate characteristics of the Baykal astrophysical observatory (BAO) from the analysis of the digital image quality, obtained from a full disk solar telescope is proposed. The image quality is estimated by a modified information-statistical “optimal window” algorithm. A large body of data (several thousand frames) is processed automatically using a hardware-software system, developed at the Zuev Institute of Atmospheric Optics SB RAS on the basis of NVIDIA® CUDA and Intel® IPP & MKL parallel programming technologies. The results of a statistical analysis of solar chromospheric H-alpha filter-grams, obtained on BAO in 2001–2002 by means of a Princeton Instruments 2048B digital camera, are presented.

Data of polarization spectronephelometric measurements have been used to study the dynamics of optical-microphysical properties of pyrolysis smoke during three days of smoke aging in the Large Aerosol Chamber of IAO SB RAS (1800 m³). The smoke was formed from low-temperature (~ 400 °C) decomposition of wood of coniferous trees (pine). The inverse problem was solved to study peculiarities in the disperse composition and the complex refractive index of smoke particles. A key difference of the microphysics of pyrolysis smokes from mixed regimes of forest biomass burning is the low content of strongly absorbing compounds (black carbon) in ultra-fine particles (radius < 150 nm). As a result, the smokes are weakly absorbing, and the single scattering albedo of dense pyrolysis smoke in the visible spectral region (~ 525 nm) at the stage of smoke formation is close to 1 and decreases after 3-day storage down to only ~ 0.96. In the size distribution of particles, the medium (~ 400 nm) and coarse (~ 850 nm) fractions are formed. At the smoke aging, the both modes shift toward smaller sizes, and for the aged smoke the medium fraction becomes the main mode in the size spectrum. The pyrolysis smoke, in contrast to mixed smokes, is characterized by the wide size spectrum up to radii of about 1500 nm. As a consequence, the effective radius of pyrolysis particles (~ 400 nm) at the smoke formation is more than twice as large as that of mixed smokes. At the smoke aging, the effective radius decreases from 400 to 170 nm. Stable correlations have been found between the volume coefficients of lidar scattering and extinction, albedo and effective radius of particles. These correlations count in favor of applicability of the single-parameter model of submicron aerosol for the pyrolysis smoke.

The paper presents unique data of 12 years (2001–2012) monitoring at Klyuchi site (Novosibirsk region) on changes in aerosol mass concentrations and concentrations of organic carbon (ОС), elemental carbon (ЕС) and total protein (ТР) in it. It was found that aerosol mass concentrations, OC, and OC/ЕС ratio have trends to increase, but TP has a trend to decrease. Seasonal changes in observed EC, OC and TP concentrations and its ratios are also revealed. The comparison of data obtained and recently published data for other Asia and Europe regions show that there are good agreements between them for some regions and no agreement for some other regions.

We discuss the specific features of the spatiotemporal variations in the atmospheric aerosol optical depth (AOD), measured during the 58th Russian Antarctic Expedition onboard RVs Akademik Fyodorov, RV Akademik Treshnikov, and at the Mirny station. It is shown that the main regularity of the spatiotemporal AOD distribution over ocean in the southern hemisphere is the linear latitudinal decrease of AOD from 0.15 at the equator to 0.025 near Antarctica. We indicate the persistence of low AOD level in Antarctica (0.022 + 0.005) during last 17 years.

The mechanism of the volcanic aerosol transport to the stratosphere after Plinian eruptions, when the maximum height of the emission does not exceed the height of the tropopause, is proposed in the paper. NOAA HYSPLIT trajectory model and open global temperature data were applied to show the role of the volcanic ash and gas clouds in the temperature change of the upper troposphere and lower stratosphere, as well as in the tropopause destruction, and therefore, in the intensification of the stratosphere–troposphere exchange. It is found out that the abnormal increase in ground-level ozone concentrations is recorded with the passage of volcanic clouds.

Range of standardized fotodetector modules are created due to cooperation of scientific groups of Institute of Physics, NASB, Belarus, and Institute of Atmospheric Optics, SB RAS, Russia. These modules provide the signal registration in wavelength range from 0.28 to 1.5 mm by the use of PMT or avalanche photodiodes under analog or photon count regimes. The software for modules control is developed and a test stand for measuring of their parameters is made. The modules are suitable for the use at CIS-LiNet lidar network stations.

Оn the basis of long series of observations obtained at TOR-station at the Tomsk Akademgorodok, an empirical model for prediction of average daily ozone concentrations is developed based on a multilayer neural network. A comparison with models based on multiple linear regression and autoregression was conducted. The method of neural network approach turned out to be the most successful among all others. It gives a possibility to describe 70% of the total variance and the average value of 50% of the variance of the standard deviation. In this case, the value of the mean square prediction error does not exceed the instrumental error of measurements.

The static chambers method and an automatic sampling and analyses system «Flux-NIES» for measuring methane and carbon dioxide fluxes from soil to atmosphere are described. Analytic system uses semiconductor sensor for methane and NDIR for carbon dioxide. System was installed and worked since 1997 to the present time near Plotnikovo settlement (Vasyugan bog) (56-51.29' N, 82-50.91' E) of Tomsk region. The technical detail of system and calculation method are represented.

The results of numerical modeling of meteorological conditions in the vicinity of the airport Bogashevo and the city of Tomsk were obtained with the help of the Mesoscale Prediction System Weather Research & Forecasting (WRF). Main attention is paid to the choice of the parameterization of microphysical processes, which is adequate for the condition of the Western Siberia, in order to obtain a reliable forecast of the intense rainfall. Comparisons of the prognostic and the actual data on the precipitates and the cloudiness were performed. It has demonstrated good capabilities of the model to forecast rainfall and aviation hazards. The best results were obtained by the use of microphysics parameterization ETA.

The growing dynamics of the relations of the far red (F₇₃₄) to red (F₆₈₂) fluorescence leaves of crymophylactic grass of Elytrigia repens differs from similar dependencies obtained for poplar and birch. It is shown that in the spring and autumn periods the value of F ₇₃₄/F₆₈₂ increases as the temperature decreases. In the urban environment of the city of Krasnoyarsk parameter F₇₃₄/F₆₈₂ is more resistant to the influence of pollutants, than the concentration of the amount of chlorophylls leaves of Elytrigia repens.