Home – Home – Jornals – Atmospheric and Oceanic Optics 2014 number 10

The theoretical aspects of self-focusing and filamentation of high-power pulsed CO₂-laser radiation with the carrier wavelength 10.6 mm in air are considered. The frequency-differential molecular absorption of atmospheric air is included in the theoretical model. It is shown that in the conditions of pulse self-phase modulation, the super-broad pulse spectrum is strongly affected by atmospheric absorption that destabilizes the filamentation process and leads to the considerable reducing of the plasma channel length formed in the beam wake.

In present experiment, in contrast to the data contained in the literature, classical linear dependence of shift of 694.380 nm water vapor absorption line broadened by hydrogen is found.

Aerosol lidar sensing of the middle atmosphere (30-65 km) was fulfilled in Obninsk within a year. Two wavelengths sensing at 355 and 532 nm enabled the separation of Rayleigh and aerosol scattering inputs to lidar signals. An increased aerosol content is found within 60-65 km range. Monthly average data of lidar sensing are compared with measurements of the meteor radio echo number in Obninsk and Kollm (Germany). The correspondence of time dependences between two kinds of data is revealed, that indicates the meteor origin of aerosol. Possible physical mechanisms responsible for the appearance of the aerosol layer observed are discussed.

The paper presents a technique for errors estimation of an average effective concentration field calculated by quasi-two-dimensional approach of the fluid location of atmosphere (FLA) method. Three ways of verification of the FLA method are presented. In spite of the fact that quasi-two-dimensional approach has a number of restrictions, all considered ways of verification indicate that the FLA method is usable one assessment of average fine aerosol concentration fields.

Work is devoted to study of physics of deformation of a charged water drop with application of numerical methods, in approach of its ellipsoidal form. The criterion of instability of a drop versus the size of its initial deformation is investigated. It is shown that at small initial disturbances, the time of development of instability considerably exceeds the period of vibrations of a non-disturbed uncharged drop. The time of instability exponentially decreases with an increase in initial deformations. This indicates an important role of external factors of deformations of charged drops leading to acceleration of their instability.

In the paper, we consider the results of analysis of structure functions of wind velocity components in the surface air layer over inhomogeneous underlying surface. Based on processing of experimental data, we singled out three basic types of structure functions and suggested analytical models for their approximation in the range of shifts, referring to inertial turbulence interval. The frequency of occurrence of the identified types of structure functions at different observation sites is estimated, and the statistics of the parameters of approximating functions is considered.

Research of seasonal and annual NDVI variations at tundra and taiga areas of Yakutia by remote sensing data (Spot Vegetation, 1998-2012) is made. The correlation analysis between NDVI and air temperature values, along with trend analysis for studied sites are made.

The original methodology of objective classification of the meteorological objects and applied climatic zoning of the Siberian region according to the total and lower cloudiness conditions was considered. This methodology is based on the method of cluster analysis with the use of the average annual values of total and lower cloudiness amount and frequencies for five gradations 0, 1-3, 4-6, 7-9, and 10 balls as the informative signs, as well as characteristics of their correlation and specific similarity criteria as a measure of homogeneity signs.

The applied climatic zoning of the Siberian region was carried out on the basis of the original methodology of an objective classification of the meteorological objects according to the total and lower cloudiness conditions (using their average seasonal values and frequencies for five gradations (0, 1-3, 4-6, 7-9, and 10 balls) as well as the special similarity criteria). 18 homogeneous cloud regions for winter, 17 for spring, 13 for summer and 14 for autumn were revealed in the result of this zoning. Local cloud atmosphere models were built for each identified homogeneous cloud region. The models include the pattern average seasonal values of total and lower cloudiness amount as well as their frequencies for five gradations.

In 2012, as a result of snow survey, investigations of dust aerosols in Blagoveshchensk were carried out. Contrast geocomical anomalies of a number of heavy metals were revealed in snow cover on the northwest industrial area. For the first time, the sulfate and sulfide mineral modes of heavy metals in dust aerosols composition were detected by scanning electron microscopy. The atmospheric air polluting sources in Blagoveshchensk were determined.

The results of joint measurements of height profiles of speed and direction of the wind by a pulsed coherent Doppler lidar “Stream Line” and radiosonde RS92-SGP in Tomsk from 23 to 27 September 2013 are presented. It has been found out that from the lidar data, measured at elevation angle of 45 deg, the wind profiles are retrieved up to heights from 400 m to 1100 m, depending on aerosol concentration in the atmospheric boundary layer. It is shown that the correlation coefficient for velocity and direction of the wind measured by lidar and radisonde equals 0.97. Mathematical expectation and standard deviation of differences of wind velocity and direction estimates from data of the radiosonde and Doppler lidar are, respectively, 0.1 m/s and 0.7 m/s for velocity and 0.8 deg and 4 deg for direction of the wind.

Experimental studies of formation and lift of combustion product clouds at burning of two identical solid-fuel charges of large-sized power plants are conducted at an open test bench for evaluating the effectiveness of the technical environmental activities in ecological protection of environment. Water irrigation of the plume of combustion products by high-pressure ring collector of water ecological protection system for deposition of polluting components of the mixture in the test bench buffer zone was used in one experiment. Results of measurements of the cloud temperature in the lift dynamics using thermal infrared image registration and video recording are presented. The characteristic features of the processes starting from formation to the maximum lifting altitude are determined. The system of parameters determined by in situ observations, applicable as input data for mathematical modeling of distribution of combustion products in the atmosphere is suggested.

Shack-Hartmann sensor represents a wavefront as centroids of the focal spots. Wavefront information can be presented as the difference of the coordinate data on centers of sub-apertures or the local wavefront tilts, or coefficients of the basis functions in the decomposition of the measured wavefront, or the values of the basis functions in its two-dimensional distribution. Voltages calculated from the sensor measurements, that control for the flexible mirror will change depending on the form of information on the wavefront. The paper presents the numerical results giving an assessment of the effectiveness of the algorithm for calculating the mirror control voltages depending on the presentation of the wavefront. The studies performed are based on the analysis of experimental data on an atmospheric path.

We considered the process of wavefront reconstruction, which is based on the use of Shack-Hartmann sensor and complex-valued artificial neural network. The pixel positions are mapped on a complex plane. The process of phase reconstruction has been tested with the help of the distorted wavefront, which was obtained in the framework of a statistical model for a turbulent atmosphere. The learning of the network is based on a genetic algorithm. The process has the fast convergence, resistance to the local errors, and dynamic adaptability.