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Atmospheric and Oceanic Optics

2016 year, number 4

Contribution of atmospheric turbulence in distortions of laser beams caused by a shock wave arising at the supersonic flowing the turret

V.A. Banakh, A.A. Sukharev
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, 1, Academician Zuev square, Tomsk, 634021, Russia
Keywords: ударная волна, турель, средняя интенсивность, турбулентность, дисперсия флуктуаций интенсивности, shock wave, turret, mean intensity, turbulence, variance of intensity fluctuations

Abstract >>
In this article, we present the results of analysis of the mean intensity, intensity fluctuations, and regular and random wandering of the optical beams crossing a shock wave arising at the supersonic flowing the turret in a turbulent atmosphere. It is shown that with increase of the optical turbulence the impact of the shock wave, arising at the supersonic flowing the turret, is so strong that even at the worst turbulent condition the aero optical impact of the shock wave on the optical beam remains predominant.

Sensing of short-living aerosol clusters by airborne lidars

A.S. Gurvich, V.A. Kulikov
A.M. Obukhov Institute of Atmospheric Physics Russian Academy of Sciences, Pyzhevsky per., 3, 119017, Moscow, Russia
Keywords: самолетный лидар, аэрозоль, airborne lidar, aerosol

Abstract >>
The paper discusses airborne lidar sensing of aerosol clusters by a laser beam sent forward in the aircraft flight direction. Numerical simulations are conducted to demonstrate the possibility of observation of the temporal evolution of short-living aerosol clusters with lifetime from few seconds to tens of seconds and horizontal scales from few hundred to few thousand meters. It is demonstrated that, unlike stationary lidars, airborne lidar observations allow the detection of the temporal evolution of aerosol clusters, without involving any additional hypotheses about their spatial and temporal structure.

Superstatistics of the optical beam scintillations over thermally nonequilibrium paths

T.I. Arsenyan1, O.M. Vokhnik1, A.M. Zotov1, A.G. Komarov2, A.V. Nesterov2, N.A. Suhareva1
1Lomonosov Moscow State University, GSP-1, Leninskie Gory, 1/2, Moscow, 119991, Russia
2Moscow Scientific-Research Institute of Radio Communication, 109029, Moscow, Nizhegorodskaja av., 32
Keywords: открытый оптический канал, статистика Тсаллиса, турбулентность, суперстатистика, индекс мерцаний, open optical channel, Tsallis statistics, turbulence, superstatistics, index of scintillations

Abstract >>
The methods of analysis of sounding optical beam intensity variations at the nonstationary nonequilibrium path output are presented. The superstatistics and nonextensive statistical mechanics apparatus was used. The connections of the first and the second moments for the experimentally obtained distribution functions of the intensity scintillations inside the subapertures of the propagated beam profile were applied to get the models for nonequilibrium flows as well as the hypotheses about the temperature distributions and aerodynamic flow phase states over the paths.

The mode convertion of the structurally stable vector beams propagating through free space optical channels

T.I. Arsenyan, E.A. Babanin, O.M. Vokhnik, A.M. Zotov, A.F. Mardanov, N.A. Sukhareva
Lomonosov Moscow State University, GSP-1, Leninskie Gory, 1/2, Moscow, 119991, Russia
Keywords: структурно-устойчивые пучки, модовый конвертер, пучки Айнса-Гаусса, открытый оптический канал, structurally stable beams, mode converters, Ince-Gaussian beams, free space optical channel

Abstract >>
The processes of rearrangement of structurally stable beams having axial symmetry in the free space data transmitting optical channels are investigated experimentally. The invariants of the structure transformation of the beam as the spatial code bearer are discussed. The estimation of correlation and dispersion parameters of the optical density modulation processes were carried out. The possibility of multiple difference in these characteristics in different directions perpendicular to the beam axis is indicated.

Estimation of integral wind velocity and turbulence in the atmosphere from distortions of optical images of naturally illuminated objects

A.L. Afanasiev, V.A. Banakh, A.P. Rostov
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, 1, Academician Zuev square, Tomsk, 634021, Russia
Keywords: скорость ветра, турбулентность, видеоизображение, пространственно-временная корреляция, wind velocity, turbulence, optical imaging, spatio-temporal correlation

Abstract >>
Simultaneous crosswind and strength of atmospheric turbulence are estimated by the classical laser scintillation method and passive optical method from analysis of the light scattered by a natural or man-made topographic objects in natural daylight illumination conditions. The passive sensing method does not require artificial light sources a consists in the formation of incoherent images of topographic objects in the natural sunlight and analysis of image distortions induced by turbulence between the object and the plane of observation. The estimates of integral crosswind and index of refraction structure constant of air were compared in atmospheric experiments at the same measuring optical path by both methods. The comparison with lidar data was made. Optical measurements of integral characteristics were accompanied by independent local acoustic measurements using a sonic anemometer.

Estimation of mean wind velocity from correlations of centers of gravity shifings for non-coherent sources in the turbulent atmosphere

D.A. Marakasov
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, 1, Academician Zuev square, Tomsk, 634021, Russia
Keywords: некогерентный источник, изображение, интегральная скорость ветра, взаимная корреляционная функция, турбулентность, incoherent source, image, integral wind velocity, mutual correlation function, turbulence

Abstract >>
The article considers the problem of wind velocity estimation from the statistics of the integral characteristics of the images of incoherent sources in the turbulent atmosphere, namely, the received power and the bias vector of the center of gravity of the image. In the framework of the first approximation of the method of small perturbations, expressions for the mutual correlation functions of these characteristics and the bias vectors for a couple of point sources registered through a couple of receivers are derived. It is shown the correlation maxima are shifted from the origin of coordinates and the shift value depends on the wind velocity. The possibility of estimation of the vector of transverse velocity averaged over the optical path from the shape of correlation functions and shifts of correlation maxima is shown.

Spatial scales of coherence of diffraction-free beams in a turbulent atmosphere

I.P. Lukin
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, 1, Academician Zuev square, Tomsk, 634021, Russia
Keywords: бесселев пучок, оптическое излучение, атмосферная турбулентность, функция взаимной когерентности второго порядка, когерентность, Bessel beam, optical radiation, atmospheric turbulence, second-order mutual coherence function, coherence

Abstract >>
Coherent properties of the diffraction-free optical beams propagating in a turbulent atmosphere are studied. The problem analysis is based on solution of the equation for the second-order mutual coherence function of a field of optical radiation. The behavior of the degree of coherence of the diffraction-free (cos and fundamental Bessel) optical beams depending on parameters of the beams and characteristics of the turbulent atmosphere is investigated. It has appeared that fundamental property of diffraction-free beams is the oscillating character of coherence degree of these beams, which is shown at low levels of fluctuations in the turbulent atmosphere. At high levels of fluctuations in the turbulent atmosphere, the degree of coherence of a diffraction-free cos beam becomes closer to the similar characteristic of a plane wave, while a diffraction-free fundamental Bessel beam becomes closer to a spherical wave. The analysis of two spatial scales of degree of coherence of optical beams has shown that the integral scale of coherence degree for diffraction-free beams is more representative characteristic than coherence of radius. The integral scale of coherence degree of diffraction-free beams is practically unequivocally connected with conditions of propagation of optical radiation in a turbulent atmosphere.

Diffraction of short pulsed Laguerre-Gaussian beams

V.A. Banakh, L.O. Gerasimova
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, 1, Academician Zuev square, Tomsk, 634021, Russia
Keywords: лагерр-гауссов пучок, импульсное излучение, параболическое волновое уравнение, Laguerre-Gaussian beam, short pulse, parabolic wave equation

Abstract >>
Based on the numerical solution of the parabolic wave equation for the complex spectral amplitude of the wave field the propagation of a short pulsed Laguerre-Gaussian beam with femtosecond duration was studied. It has been shown that the difraction broadening of the Laguerre-Gaussian beam decreases with the pulse duration in comparison with continuous wave radiation.

Estimation of the effective beam width of axially symmetric laser beams propagating in the turbulent atmosphere using the Pointing vector streamlines

D.A. Marakasov, D.S. Rytchkov
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, 1, Academician Zuev square, Tomsk, 634021, Russia
Keywords: турбулентность, эффективный радиус, линии тока, взаимная функция когерентности, turbulence, effective beam width, streamlines, mutual coherence function

Abstract >>
In the given paper, using the Pointing vector streamlines, the effective beam width dependence on initial field distribution of axially symmetric laser beam, propagating in the turbulent atmosphere, is investigated. Spatial evolution of effective beam widths of ring-shaped laser beams, such as Laguerre-Gaussian and dark hollow beams was examined in comparison with Gaussian beams under condition that the beam power in transmitter aperture of an atmospheric optical system is the same for all laser beam modes studied in the paper. It was shown that in the case of medium-to-strong turbulence effective beam widths of high-order Laguerre-Gaussian and dark hollow beams can be less than effective beam width of a Gaussian beam in the atmosphere.

Optical-microphysical and physical-chemical characteristics of Siberian biomass burning: small-scale fires in an aerosol chamber

O.B. Popovicheva1, V.S. Kozlov2, R.F. Rakhimov2, V.P. Shmargunov2, E.D. Kireeva1, N.M. Persiantseva1, M.A. Timofeev1, G. Engling3, K. Elephteriadis4, L. Diapouli4, M.V. Panchenko2, R. Zimmermann5,6,7, J. SchnelleKreis6,7
1Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, 1, Leninskie gory, GSP-1, Moscow 119415, Russia
2V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, 1, Academician Zuev square, Tomsk, 634021, Russia
3National Tsing Hua University, Hsinchu, Taiwan
4Institute of Nuclear and Radiological Science & Technology, 15341 Ag. Paraskevi, Attiki, Greece
5Joint Mass Spectrometry Center, 85764 Neuherberg, Ingolstaedter Landstr. 1, Germany
6Institute of Chemistry University of Rostock, Dr.-Lorenz-Weg 1, 18059 Rostock, Germany
7Helmholtz Virtual Institute of Complex Molecular Systems in Environmental Health, Germany
Keywords: тление, открытое горение, смешанное горение, сибирские биомассы, Большая аэрозольная камера, дымы, характеристики дымовых частиц, smoldering, open burning, mixing burning, Siberian biomasses, Large Aerosol Chamber, smokes, smoke particle’s characteristics

Abstract >>
Impact of combustion phases of typical Siberian biomass on optical, microphysical, and physical-chemical properties of smoke aerosols were investigated in small-scale fires at the Large Aerosol Chamber (LAC). The comprehensive analysis has revealed the influence of combustion temperature on formation and time evolution of pine and debris emission characteristics. Size distributions and complex refractive indices in the ranges of ultrafine, fine, and coarse particles were determined from polar spectronephelometer measurements of the angular aerosol scattering. In smoldering phases, smoke is found to be weakly absorbing while mixed fires also emit strongly absorbing soot particles produced in open flaming phases. Characteristics of aerosol microstructure such as morphology and composition were analyzed. Group Soot and Organics were identified as micromarkers of Siberian biomass burning in open flaming and smoldering phases, respectively. Carbon fraction (organic and elemental carbon), chemical compounds, and water-soluble ionic fraction exhibit the strong dependence on the combustion phase. Anhydrosugar (levoglucosan) was determined in smoldering fires as the stable molecular marker of Siberian pine burning. A number of chemical compounds were found to act as specific markers of soft wood. At smoke aging in a chamber the condensation of organic and inorganic species leads to transformation of the aerosol surface chemistry and formation of the particle group rich by potassium. Thus, the complexicity and changeability of chemical composition and microstructure of atmospheric aerosol pollution during Siberian wildfires were realized.

Peculiarities of lasing in solutions of Rhodamine 6G with nanoparticles free of plasmon resonance

V.A. Donchenko1, Al.A. Zemlyanov1, M.M. Zinoviev2, N.S. Panamarev2, A.V. Trifonova2, V.A. Kharenkov1
1Siberian Physical-Technical Institute of the Tomsk State University, Tomsk, Russia, 634050, Tomsk, pl. Novo-Sobornaya, 1, Russia
2National Research Tomsk State University, 36, Lenin Avenue, Tomsk, 634050,Russia
Keywords: активная среда, наночастицы, коллоидные растворы, безрезонаторная генерация, плазмонный резонанс, active medium, nanoparticles, colloidal solutions, lasing, plasmon resonance

Abstract >>
The threshold characteristics of lasing in a layer of colloidal solution of dye Rhodamine 6G with plasmon-resonance Au nanoparticles and non-plasmon-resonance Pt nanoparticles excited by a wavelength of 532 nm are experimentally investigated. The spectral dependence of the scattering and absorption cross sections of nanoparticles of gold and platinum are calculated within the Mie theory. It is established experimentally that the addition of nanoparticles to the active medium reduces the lasing thresholds by two orders of magnitude. It is shown that the lasing threshold value is 1.5-2 times lower when adding gold nanoparticles than when adding platinum nanoparticles of the same concentration.

Measuring the absorption in nitrous oxide and methane at first-overtone CO laser wavelengths using topographic target and receiving telescope

A.A. Ionin1, L.Yu. Kalnitskii2, I.O. Kinyaevskii1, Yu.M. Klimachev1, A.Yu. Kozlov1, A.A. Kotkov1, G.G. Matvienko3,4, O.A. Romanovskii3,4, S.V. Yakovlev3,4
1P.N. Lebedev Physical Institute of the Russian Academy of Science, 53 Leninskij Prospekt, 119991, Moscow, Russia
2Moscow Institute of Physics and Technology, per. Institutskiy, 9, Moscow Region, Dolgoprudnyiy, 141700, Russia
3V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, 1, Academician Zuev square, Tomsk, 634021, Russia
4National Research Tomsk State University, 36, Lenin Avenue, Tomsk, 634050,Russia
Keywords: обертонный CO-лазер, газовый анализ, атмосфера, дифференциальное поглощение, first-overtone CO laser, gas analysis, atmosphere, differential absorption

Abstract >>
Laboratory experiments with a first-overtone CO laser are performed to simulate a lidar system. The trace remote sensing scheme of atmospheric gases (nitrous oxide and methane) at emission lines of the pulsed first-overtone CO laser is tested using topographic target and receiving telescope. Results of the measurements of absorption of the first-overtone CO laser operating at 20 selected emission lines in gas mixtures with the gases studied at various configurations of the experimental scheme are presented.

Method for reconstruction of monthly average data on water transparency for the North-West Black Sea

A.S. Lubkov1, E.N. Voskresenskaya1, A.S. Kukushkin2
1Natural and Technical Systems Institute of the RAS, 28, Lenina St., Sevastopol, 299011, Russia
2Marine Hydrophysical Institute of the RAS, 2, Kapitanskaya St., Sevastopol, 299011, Russia
Keywords: прозрачность, нейронные сети, речной сток, гидрометеорологические условия, Черное море, transparency, neural network, runoff, hydrometeorological conditions, Black Sea

Abstract >>
To reconstruct the data of hydrophysical parameter observations, a model based on a neural network with the teacher has been suggested. The indices of global climate modes of the ocean-atmosphere system were applied as the model input. The processes of the model teaching and adaptation, which allow one to find the most accurate solution of the problem of modeling, is described. The comparison of modeled monthly average Danube's runoff with data of observation demonstrated their good correspondence. Missed in some years observation data on sea water transparency (depth of white disc visibility) were reconstructed. The proximity of reconstructed and observed depths of white disc visibility was noted. Some features of interannual variability of reconstructed data on sea water transparency caused by both climatic factors during 1950-1962 and changes in the chlorophyll а concentration during 1998-2010 were found.

Dosimetry of visual laser landing systems

G.A. Kaloshin1, S.A. Shishkin1, V.I. Anisimov2, V.V. Zhukov2
1V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, 1, Academician Zuev square, Tomsk, 634021, Russia
2Scientific-Research Institute "Jekran", 443022, Samara, ave. Kirov, 24
Keywords: лазерно-опасная зона, лазерная система посадки, аэрозольное ослабление, программный пакет, laser-dangerous zone, laser landing system, aerosol extinction, software package

Abstract >>
The methodological issues and theoretical results related to determination of the boundaries of laser-hazard distances (LHD) when eyes are exposed to direct and scattered radiation produced by a laser landing system (LLS) are discussed. LHD calculation algorithms during LLS operation in field conditions are considered. LHD have been calculated for a single and a group of laser sources for a variety of weather conditions. Computer software for laser radiation dosimetry calculation during LLS operation in field conditions is suggested.