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Results of the joint lidar-actinometric experiment on the study of optical properties of high-level clouds and their effect on the solar radiation fluxes measured at the Earth's surface are described. Conclusions about the effect of specular clouds on a decrease in radiation fluxes compared to non-specular ones depending on the Sun’s zenith position are drawn.

Results of the complex lidar and actinometric studies of the characteristics of cirrus containing crystalline ice particles are discussed. The greatest attention is paid to clouds consisting of horizontally oriented ensembles of ice crystals. Orientation of the crystalline particles in clouds is estimated from the backscattering phase matrix, which is determined based on the data obtained with the polarization lidar directed vertically to the zenith. Solar radiation fluxes are measured using the standard methods with an actinometer and a pyranometer. It is shown that under certain weather conditions ice crystals at altitudes of cirrus formation can be oriented horizontally, which significantly affects the transmission of solar radiation.

Results of the experiments on laser polarization sensing of high-level clouds with anomalous backscattering (specular clouds) performed with the high-altitude polarization lidar developed at National Research Tomsk State University (NR TSU) with a short lidar return accumulation time (about 3 minutes) are described. It has been shown that the preferred horizontal orientation of ice crystals in clouds is manifested even at such a short signal accumulation time intervals. Interpretation of the results of the experiment with longer accumulation leads to the identification of a cloud as a specular one despite the presence of not only a specular, but also non-specular local areas in it.

Differential optical absorption spectroscopy (DOAS) gas-analyzer was successfully tested. Ultraviolet light emitting diodes and high pressure Xe arc lamp were employed as a light sources. Recent developments in fibre-coupling telescope technology and the availability of UV LEDs allowed us to construct a portable instrument. The DOAS system consisted of a coaxial telescope, a spectrometer, and retroreflector. Gas analyzer spectral data bank includes more than 40 molecules absorbed in UV spectral region. Minimally detected concentration is the unit of ppb on paths up to 500 m. The results of the field test measurements of pollutants in Tomsk are presented

Optical models of high-level clouds (HLCs) used for calculation of radiation fluxes in the atmosphere are analyzed briefly. Results of the experiments on polarization laser sensing of cirrus performed with the lidar developed at the National Research Tomsk State University are described. Optical and microphysical characteristics of such clouds obtained from the results of measurements of their entire backscattering phase matrices are presented. It is shown that the orientation of crystals in the cirrus significantly affects the transmission of shortwave solar radiation. This fact proves incorrectness of the representation of real crystalline particles in HLCs with spherical particles with the corresponding effective radii during calculating the Earth’s radiation budget.

For microparticles, the intensity of spontaneous scattering is directly proportional to the volume. However, model calculations show that when the particle dimension parameter increases in the region 0.5

The software complex for automation of processing the results of the experiments on sensing of high-level clouds with the high-altitude polarization lidar developed at National Research Tomsk State University is described. The software performs the following operations: preliminary processing and visualizing experimental data; calculating optical and geometrical characteristics of the observed aerosol layers; downloading meteorological data corresponding to the place, date, and time of the lidar experiment; as well as forming summary report on the performed processing.

Results of the experiments on polarization laser sensing of aircraft contrails performed with the lidar developed at the National Research Tomsk State University are described. The altitudes of the lower and upper borders, backscattering phase matrices, optical thickness, and scattering ratios of the observed aerosol formations are determined. Microstructure parameters of the contrails are estimated by comparing the elements of backscattering phase matrices not only obtained from lidar experiments, but also calculated theoretically. The meteorological conditions for the formation of the preferred horizontal spatial orientation of ice crystals in contrails are established.

In the paper the analyses of the lidar measurements data of optical parameters of the cirrus clouds over the Tomsk city are presented. The valuation of the microphysical properties of the cirrus clouds was done by the backscattering matrices that were measured by the high-altitude polarization lidar (wavelength is 0.532 μm) from National Research Tomsk State University in 2016-2018. For the interpretation of the laser sensing data we used the backscattering matrices database designed in V.E. Zuev Institute of Atmospheric Optics, Russian Academy of Sciences, Siberian Branch. An attempt to interpret the measured matrix using the quasi-horizontal orientated hexagonal columns with the 1000 μm modal size Lmod is incorrect in view of the fact that the particles with this size are very unlikely in existence of nature. It was demonstrated that the calculated backscattering matrices together with proposed algorithm could be used for the valuation of microphysical properties of the measured backscattering matrices.

The paper presents the results of numerical simulation of the dispersion properties of surface plasmon-polaritons at the interface between an active composite medium based on metallic nanoparticles and a substrate of the same metals in the visible wavelength range. It is shown that the amplification and dispersion properties of surface plasmon polaritons in these structures can be varied within wide limits by varying the concentration of nanoparticles.

In the present report, results of the experiment on polarization laser sensing of contrails performed for one and a half days are discussed. The altitudes of boundaries of the aerosol layers, their backscattering matrices, optical thicknesses, and scattering ratios are determined. The vertical profiles of lidar returns are analyzed. The results are compared with the meteorological data at the altitudes of formation of high-level clouds.

A complex experiment on the investigation of radiation characteristics of cirrus is performing since 2016. In the experiment, solar radiation fluxes are measured near the Earth’s surface and the orientation degree of ice crystals in cirrus is estimated using a polarization lidar. Results of the experiment are discussed. Significant effect of the orientation degree of cirrus particles on the transmission of solar radiation is found in a number of experiments.

The results of the investigation of radiation characteristics of cirrus consisting of crystalline ice particles with a preferred orientation are discussed. The orientation degree of particles is estimated from the backscattering phase matrices, which are determined with the high-altitude polarization lidar developed at National Research Tomsk State University. It is shown that the orientation of ice crystals in clouds with anomalously high backscattering affects significantly the transmission of solar radiation.

Results of complex experiments, in which flows of solar radiation are measured near the Earth’s surface in the presence of cirrus cloudiness and the orientation degree of ice crystals in cirrus is estimated using a polarization lidar, are discussed. Significant effect of the orientation degree of cirrus particles on the transmission of solar radiation is found in a number of experiments.

Results of experiments on polarization laser sensing of high-level clouds performed at the high-altitude polarization lidar developed at National Research Tomsk State University are discussed. It is shown that orientation of crystalline ice particles in a cloud leads to different values of the measured depolarization ratio for the same cloud, which depends significantly on the azimuthal orientation of the polarization plane of sensing radiation.

The cross-sections of attenuation, scattering and absorption of spherically aggregated metal nanoparticles in dependence on the aggregate size, the degree of its filling with nanoparticles and physical properties of nanoparticle material have been estimated, according to the model of the effective medium and the theory of G. Mie. In that case, the concentration of the nanoparticles changes radially.

The paper presents the results of the Helmholtz equation solution by the method of perturbation theory in the spherical coordinate system for the Debye potentials for weakly heterogeneous media based on metal nanoparticles and the dielectric matrix. In that case, the dielectric function of a composite changes in space in the radial direction.

Although the fact that lidars are used more than half a century, so many of the technical and methodological problem of the laser sensing has not been resolved. Laser sensing of optically dense aerosol formations (such as clouds or fog) belongs to the need of careful study. This is because the lidar signal from such formations is due not only single, but also multiple scattering, which significantly affects both the intensity value and the state of polarization of the received radiation. We have obtained an analytical expression for the time delay of the lidar return from the cloud layer due to multiple scattering. It is shown that the value of this lidar return is determined by the lower boundary, the microstructure and the thickness of the cloud layer, and a field-of-view of lidar receiving system.

Results of observation of the dynamics of evolution and decay of an aircraft condensation jet are described. Polarization lidar is used to determine the upper and lower boundaries of the aerosol layer, its optical thickness, scattering ratio, and backscattering phase matrix.

The problem an estimation of influence the crystal orientation in the ice clouds on the radiation transmission is solved. The technique of synchronous measurements of total radiation with the calculation of the backscattering matrix cirrus clouds using lidar is provided.

An active differential optical absorption spectroscopy (DOAS) gas-analyzer was successfully tested. The DOAS system consisted of a coaxial telescope, a spectrometer, an analyzer and retroreflector. A high pressure 150-W Xe arc lamp and UV LEDs were employed as a light source. In order to record the spectra, a monochrometer with a grating and photodiode array was adopted. Gas analyzer spectral data bank includes more than 40 molecules absorbed in UV spectral region. The measured absorption spectra were evaluated by using a least-squares fit to determine the average mixing ratio of each species in the atmosphere. As a result of experiments time series of concentrations of gases polluting the atmosphere were trace measured. Minimally detected concentration is the unit of ppb on path length from 200 to 500 m at the time of accumulation up to 3 minute. The results of the field test measurements of pollutants in Tomsk are presented.

The paper presents the results of researching surface plasmon polaritons dispersion on the "composite medium and metal substrate" border within a visible wavelength range. The composite dielectric function varies in space according to the periodic law. The solution to this problem has been presented as an inhomogeneous wave for which the field amplitude distribution has been written in an analytical form and dispersion relations have been obtained.

Asian dust appears in the atmosphere in spring, spreads over long distances, and affects significantly on the environment. Scattering and absorption of Asian dust can be observed in the atmosphere at different angles on the basis of diurnal movement of the Sun. For this purpose, we used a solar tracker, which provides the Sun pointing and tracking. We present an optimal optical model of the solar tracker for atmospheric spectroscopy. A solution of the problem of loss stability of еру tracker pointing at the Sun near the zenith is shown. Test results demonstrate the efficiency of the proposed optimization methods.

The paper gives the results of computer simulating reflectivity of a flat structure made of composite material on the basis of Ag, Ni, Al, Cu nanoparticles and a substrate of the same metals within the visible wavelength range. The possibility of broadband optical antireflection of a metal surface using nanoparticles of the same metals by forming in the near surface layer of the metal being made anti-reflecting a composite layer is researched. Within the visible wavelength range the dispersion characteristics of the reflectivity of the composite metal-dielectric layer on a metal substrate have been calculated for different values of the filling factor and the thickness of the composite layer both for the metals having plasmon resonances (Ag, Cu) within the visible range and for the metals plasmon resonances of which do not fall in the visible wavelength range (Al, Ni).

Joint analysis of the data on polarization laser sensing of cirrus obtained using the ground based polarization laser developed at National Research Tomsk State University (Russia, Tomsk) with the results of theoretical calculations is described. The possibility of estimation of the microstructure parameters of cirrus with a preferred orientation of ice crystals on the basis of comparison of the backscattering phase matrices obtained experimentally and calculated theoretically is discussed.

Methodology for determination of the optical and geometric characteristics of clouds is described. Problems of processing data obtained in experiments on polarization laser sensing of the atmosphere are discussed. Technique for reduction of the phase matrices of cirrus obtained with the high-altitude polarization lidar developed at National Research Tomsk State University to the symmetry plane affixed to the preferred orientation of ice crystals in cirrus is described. The experimental data are compared with the data of numerical modeling of phase matrices in the physical optics approximation and meteorological conditions over the lidar at cirrus altitudes. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

A differential optical absorption spectroscopy (DOAS) gas-analyzer was successfully tested. A high pressure 150-W Xe arc lamp was employed as a light source This system consisted of a coaxial telescope, a spectrometer, an analyzer and retroreflector. In order to record the spectra, a monochrometer with a grating and photodiode array was adopted. Gas analyzer spectral data bank includes more than 30 moleculas absorbed in UV spectral region. The measured absorption spectra were evaluated by using a least-squares fit to determine the average mixing ratio of each species in the atmosphere. A number of air pollutants concentrations: SO2, NO2, O3, etc were trace measured. Minimally detected concentration on pathlength 400 m is the unit of ppb at the time of accumulation of 2 min. The results of the field test measurements of pollutants in Tomsk are presented.

According to the model of the effective medium and G. Mie theory, attenuation cross-sections, cross-sections for scattering and absorption for metal nanoparticles nanosized aggregates have been assessed depending on the aggregate’s size , level of the aggregate’s filling with nanoparticles and physical properties of the nanoparticles material.

Experimental data on the variability of vertical and temporal aerosol structure obtained with a lidar complex comprising the TSU high-altitude lidar and the IAO SB RAS station of high-altitude lidar sensing of the atmosphere in 2011-2013 are presented in the work. The special feature of this observation period was practical absence of volcanic activity with emissions into the stratosphere, as well as in 2010. Therefore, the possibility arose of studying the monthly behavior of the vertical structure of the background aerosol in the stratosphere at nights during a three-year period.

In this article results of observations of upper-layer crystal clouds are analyzed. Estimates about shape and preferred orientation crystals of clouds are performed. Information on the vertical stratification of the pressure, temperature, wind direction and modulus near the observation point was considered.

The task of laser sensing of droplet clouds by coaxial lidar is considered. Lidar return due to single scattering is formed in the volume bounded by the radiation pattern of the transmitter, while the double-scattering is determined by a receiving system field of view. The volume of the scattering medium exceeding a receiving system field of view forms the signal higher scattering orders ( > 2). The results of the numerical modeling of the distribution (in the recording plane) polarization characteristics of lidar signal from droplet clouds in the double scattering approximation in comparison with the results of the physical model experiment simulating sounding of a droplet cloud are discussed in this paper.

We present results of joint analysis of the data of high-level cloud sensing with a polarization lidar and satellite radiometer MODIS. The possibility of detection from space of cirrus clouds with preferred orientation of ice crystals is discussed.

Experimental results of polarization laser sensing of cirrus with anomalous backscattering are presented. The technique of determining the optical and geometrical characteristics of clouds is described. Experimental data are compared with the meteorological conditions at altitudes of cirrus above the lidar location and with the results of numerical modeling of phase matrices in the approximation of physical optics. The recurrence frequency of meteorological characteristics of “mirror” cirrus is estimated.

The paper reports the results of strobing the lidar signal by an electro-optical shutter (EOS). The authors discuss the possibility to reduce the backscattered signal power in the near field up to 10-12 times, to increase the probe pulse energy by an order of magnitude, and thereby to improve the signal-to-noise ratio in atmospheric sensing in the daytime.

In the article the lidar observations of the winter stratosphere warming manifestations of (SW) 2011-13 over Tomsk are considered. In 2010/11 the winter warming took place in January with insignificant positive temperature deviations from the mean monthly values in its first decade and then two maxima on the 14 th and 15 th of January at the altitude of 30-40 km with a deviation to 45К. In 2011/12 the beginning of the SW was recorded from lidar measurements on December 26 and lasted for two decades of January. The maximum development of SW was at the end of December 2011 – the first decade of January. The biggest temperature deviations were at the 40-60К level in the height interval of 35-45 km. In 2012/13 the SW began on December 25. The phase of its maximum development fell on the 1-4 th of January when the stratopause altitude dropped on 30 km and the maximum temperature deviation from the model at this level reached 70K. In contrast to the first two warming (minor), the last was referred to the major type wherein air mass circulation change happened in the upper stratosphere over Tomsk ((http://www.geo.fu-berlin.de/en/met/ag/strat/index.html).).

The paper focuses on retrieving the microphysical characteristics of cirrus clouds from lidar data. The beam-splitting algorithm developed by the authors within framework of physical optics approximation has been used to solve the problem of light scattering by the hexagonal ice crystals. The paper presents the color ratio, depolarization ratio, and lidar ratio that have been calculated for the first time for quasi-horizontally and randomly oriented hexagonal ice particles. The lidar experimental data measuring simultaneously the depolarization ratio and color ratio in cirrus clouds are also presented.

We propose a model of distribution of angular deviation of large particles orientation in a crystal cloud from the horizontal position of their big diameters in the process of their fall due to gravity. A single-parameter distribution of particles over angles of orientation is obtained. The distribution parameter is shown to be dependent on the particle size and the rate of energy dissipation in the turbulence cells. The dependence turns out to be much stronger than those in models proposed earlier.

We discuss the possibility that particles of a crystal cloud can take a preferred orientation with respect to wind direction under the action of aerodynamic forces in the atmosphere. It is shown theoretically that the preferred orientation can be caused by wind speed pulsations and by the forces applied to a particle falling due to gravity in the presence of wind speed gradient. The theoretical estimate of the parameter of the function of particle orientation distribution over azimuth angles well agrees with its experimental estimate from the backscattering phase matrices of cirrus clouds obtained from data of polarization lidar measurements.

The particles of upper clouds are ice crystals with various sizes and shapes. Under certain conditions they can be oriented in space. This circumstance leads to the significant anisotropy of light in cirrus clouds that should be taken into account when solving problems of radiation propagation through the atmosphere. Acquiring the information on parameters of particle orientation in ensembles of actual clouds is still an urgent and poorly studied problem. In this connection, we have developed a lidar technique for measuring the backscattering phase matrices (BSPM) that enables one to acquire such information. Based on processing of 450 experimentally measured BSPMs we have drawn the following conclusions: - in 90 to 95 % cases the orientation of the larger diameters of particles along the azimuth direction was observed, though in 70% of these cases the orientation was only weakly pronounced against the background of particles that had no preferred orientation in the azimuth plane. However, the backscattering coefficients for linearly polarized light can strongly depend on the orientation of the polarization plane. - the larger diameters of particles practically always lied in the horizontal plane, and in 50% cases the degree of this orientation should be recognized essential. The latter means that the extinction coefficient of such clouds should strongly depend on the angle of radiation incidence on the cloud layer.

Separation capability of singly and multiply scattered components in a lidar receiving system based on the use of spatial filtering of lidar returns is considered. A calculation example for a return power density is shown. A procedure for determination of a multiple scattering spot parameter is described. Experimental results of sounding the clouds are presented. Various instrumental realizations of the spatial filters for the practical use in elastic scattering lidars are discussed.

It is known, lidar signal intensity due to double scattering depends on the particle size distribution of under investigation aerosol formation. The most sensitive to microstructure of sounding aerosol is lidar signal component, which is defined by diffraction component of the phase function. Analytical expressions for return scattering radiation received from aerosol cloud at different distances are analyzed in this report. Also possible methods of extraction from lidar signal sensitive to microstructure sounding aerosol component are considered. Theoretical analysis results are reported.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The given work is devoted to a problem of numerical simulation and analysis of the vertical cavity lasers parameters with the purpose of numerical simulation methods improving. The analysis of the VCSEL with the help of the mathematical model, based on beam propagation method, are presented. The dependence of the VCSEL dynamic behavior on the temperature dependence of the gain coefficient is submitted. With the help of extended system of the rate equations for VCSEL the modulation characteristics are obtained. Analysis of the lasing wavelength dependence on thermal gain coefficient is carried out.

Several physical factors that govern the light scattering scenario in optically anisotropic media are discussed and the degree to which they may affect the date of laser sounding of crystal clouds is assessed. Among the peculiarities of light propagation and scattering in such media there are: 1) possible changes in the state of polarization of a sounding beam; 2) the transformations of the polarization state and extinction of sounding radiation may depend on the direction of sounding; 3) the data of laser sounding regarding the backscatter and lidar depolarization may be ambiguous. The matter is that in an anisotropic medium these properties of the backscattered radiation depend on the polarization state of a sounding beam and on the orientation of the lidar. As the calculated and experimental data presented in this paper show, the change of the sounding beam polarization state during the propagation in cirrus clouds may be neglected in the majority of practical cases. At the same time, the dependence of the radiation extinction on the direction of sounding, as well as the ambiguity in sounding data mentioned above should certainly be taken into account.