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Atmospheric and Oceanic Optics

2022 year, number 5

Propagation of phase-modulated high-power femtosecond laser pulses in the self-channeling and filamentation mode in air

Yu.E. Geints, A.A. Zemlyanov, O.V. Minina
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: femtosecond laser pulse, phase modulation, self-focusing, filamentation, self-channeling, post-filamentation channel

Abstract >>
Propagation of high-power phase-modulated femtosecond laser pulses in air is numerically simulated. Spatial modulation of the initial pulse wavefront is carried out using a programmable phase plate consisting of segments arranged in a checkerboard pattern with a variable wave phase jump. The self-focusing, filamentation and post-filamentation channeling of radiation for phase-modulating masks with different phase shifts at the boundaries of neighboring segments are studied within the numerical solution of the nonlinear Schrödinger equation for the time-averaged electric field amplitude. The filamentation domain in air for certain pulse phase modulation types is shown to be significantly shifted (along the coordinate) and elongated compared to an unmodulated pulse. In addition, it is found that the use of phase modulation makes it possible to reduce the angular divergence of high-intensity light channels generated during the post-filamentation propagation stage. This provides a possibility of self-channeling of radiation at distances multiple of the Rayleigh length.

Quantitative spectral analysis by femtosecond pulse laser-induced breakdown spectroscopy

P.A. Babushkin, G.G. Matvienko, V.K. Oshlakov
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: femtosecond, sounding, plasma, spectral analysis, LIBS, FS-LIBS

Abstract >>
The results of analysis of aerosol of an aqueous solution of NaCl by femtosecond-pulse laser-induced breakdown spectroscopy (FS-LIBS) are considered. The results of estimating the impurity (Na) concentration by the analytical pair method using the additive method are presented. The radiation of the atomic nitrogen ion N+ at a wavelength of 500.515 nm from atmospheric nitrogen molecules in the filamentation region was taken as the internal standard line. A possibility of estimating the concentration of the both desired substances, the radiation of which is recorded, and the compound containing it is shown. The results are of interest for the development of femtosecond lidar sensing methods.

Estimation of the efficiency of laser excitation of the B2Sigma+ (v' = 0) - X2Pi(v'' = 0) transition of phosphorus oxide

S.M. Bobrovnikov1,2, E.V. Gorlov1,2, V.I. Zharkov1, S.N. Murashko2
1V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
2National Research Tomsk State University, Tomsk, Russia
Keywords: phosphorus oxide, PO-fragments, absorption spectrum, laser excitation, thermalization, organophosphates

Abstract >>
We present the results of calculating the vibrational and rotational terms of the X2Π and B2Σ+ electronic states of the phosphorus oxide (PO) molecule. The absorption spectrum corresponding to the electronic transition B2Σ+ (v′ = 0) - X2Π (v″ = 0) has been calculated. The efficiency of laser excitation of PO molecules is estimated as a function of the spectral parameters of the radiation. It has been established that the excitation efficiency of the B2Σ+ (v′ = 0) - X2Π (v″ = 0) electronic transition of the PO molecule is approximately an order of magnitude lower than that of the A2Σ+ (v′ = 0) - X2Π (v″ = 0) transition. The result is of practical importance from the point of view of choosing the optimal scheme for laser excitation of the fluorescence of PO-fragments in the implementation of the method of remote detection of organophosphates.

Generation of secondary organic aerosols on needle surfaces and their entry into the winter forest canopy under radiometric photophoresis

M.P. Tentyukov1,2, B.D. Belan1, D.V. Simonenkov1, V.I. Mikhailov3
1V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
2Pitirim Sorokin Syktyvkar State University, Syktyvkar, Russia
3Institute of Chemistry of the Komi Science Centre of the Ural Division RAS, Syktyvkar, Russia
Keywords: dynamic light scattering, UV spectrometry, efflorescence, polyphenols, secondary organic aerosols, radiometric photophoresis, needles, winter

Abstract >>
The results of the laser granulometry of nanosize fraction of precipitated aerosols and UV spectrometry of water washes from the surfaces of needle of different age of four species of forest-forming plant species are analyzed. The phenolic compounds efflorescence activity on the needle surfaces is assessed for the period of winter dormancy of plants. A possibility of the secondary organic aerosols geeration as a result of photoactivated reactions between phenolic compounds and a precipitated aerosol substance has been shown. The possibility of secondary organic aerosols entering the winter forest canopy under the radiometric photophoresis is discussed. It is assumed that secondary aerosols photophoresis in the field of IR from the snow cover surface (snow photophoresis) can significantly affect the vertical transfer of secondary organic aerosols in the winter coniferous forest canopy.

Dependence of the intensity of emission lines of chemical elements on the duration of laser pulses in the method of filament-induced breakdown spectroscopy of aqueous aerosol

A.Yu. Mayor1,2, S.S. Golik1,2, Yu.S. Tolstonogova1, A.A. Ilyin1,2, O.A. Bukin1,3
1Far Eastern Federal University, o-v Russkij, Russia
2Institute of Automation and Control Prosesses Far Easten Branch of the Russian Academy of Science, Vladivostok, Russia
3Admiral G.I. Nevelskoy Maritime State University, Vladivostok, Russia
Keywords: filament-induced breakdown spectroscopy, laser pulse duration, aerosol analysis, femtosecond radiation

Abstract >>
The dependence of the intensity of emission lines Ca (393.3, 396.8, 422.6 nm), Mg (383.6 nm), and Na (589 nm) on the laser pulse duration in the method of filament-induced breakdown spectroscopy is investigated. The filament was excited in seawater aerosols droplets of 0.8-2 mm in size by laser pulses of 70, 230, 500, and 900 fs in duration at a constant pulse energy of 3.0 mJ. It is shown that with an increase in the laser pulse duration, the intensity of the emission lines of the studied elements increased, with the exception of the magnesium line. Optimal values of the laser pulse duration for the excitation of Ca, Mg, and Na lines in a seawater aerosol are derived.

Comparison of turbulent lidar data with meteorological measurements

I.A. Razenkov
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: atmospheric turbulence, backscattering enhancement effect, turbulent lidar, kinetic energy dissipation rate

Abstract >>
The turbulence parameters obtained using lidar are compared with the parameters determined from the average values of velocity and temperature in the surface air layer. The results of observations of the structural constant of the refractive index Cn2 obtained from the ratio of the turbulent lidar returns in the surface air layer when working along a slightly inclined sounding path are presented. A method for determining the rate of kinetic energy dissipation from lidar data has been tested.

Ozone anomalies in the stratosphere of the Arctic and northern Eurasia: Comparison of 2011 and 2020 events using TEMIS and Aura MLS data

O.E. Bazhenov
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: total ozone content, ozone concentration, ozone anomaly, Aura MLS data, TEMIS observations

Abstract >>
In winters-springs 2010/2011 and 2019/2020, there were the strongest anomalies of ozone layer in the Arctic stratosphere in the total satellite era. They were due to extraordinarily strong and long-lived stratospheric polar vortices, entailing unprecedented chemical ozone destruction. The analysis of the TEMIS data indicates that the total ozone content (TOC) deviations from the multiyear (2003-2019 except 2011) average were from 37 to 44% in 2011 and from 45 to 55% in 2020 at Arctic observation stations; and from 27 to 36% in 2011 and from 27 to 32% in 2020 in the subarctic latitudes. Based on the Aura MLS data, the minimal temperatures were 8-12% below normal over the Arctic in 2011 and 8-13% below normal in 2020. The ozone concentration dropped to 23% of the multiyear average at an altitude of 20 km on March 22, 2011, and to 6% at an altitude of 19 km on April 15, 2020, for Alert. A detailed correlation analysis showed that the deviations in the concentrations of water vapor and ozone, water vapor and temperature, and ozone and temperature correlate stronger in 2020 than in 2011. The correlations decrease toward the vortex periphery owing to the exchange of air masses between the Arctic and middle latitudes, becoming weakly significant outside the Arctic circle.

Formation of fogs downstream of the Krasnoyarsk hydropower plant on the Yenisei river

N.Ya. Shaparev, A.V. Tokarev, O.E. Yakubailik
Institute of Computational Modelling SB RAS, Krasnoyarsk, Russia
Keywords: fogs, Yenisei River, meteorological conditions, water temperature, remote sensing

Abstract >>
Generation of fogs downstream of the Krasnoyarsk hydropower plant on the Yenisei River during 2020 is studied. Meteorological conditions at the time of fog generation were recorded on the geoportal developed by the authors; water temperatures were taken at a gauging station; fogs were recorded with the help of video surveillance cameras. Data analysis showed generation of advective cooling fogs in summer and advective steam fogs in winter, early spring, and autumn. Cooling fogs are generated due to the cooling of the moist air as the lower atmosphere interacts with a colder moving water surface. Steam fogs result from the advective cooling of water vapor on the river surface by the colder adjacent atmosphere. The spatial distribution of steam fogs was derived from remote sensing data.

Wind effects on the distribution of plankton and nutrients during the autumn cooling of Lake Baikal

B.O. Tsydenov
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: wind, autumnal thermal bar, numerical simulation, plankton, phosphate, Lake Baikal

Abstract >>
The results of mathematical simulation of biogeochemical processes during the autumn cooling of the lake are presented. The influence of wind on the distribution of phyto- and zooplankton, nitrate, ammonium, and phosphate nutrients is studied during the existence of the autumnal thermal bar in Barguzin Bay of Lake Baikal. Numerical simulations show the autumnal thermal bar in combination with the effect of western winds, which act opposite to the thermal front direction, to significantly slow down the transport of plankton biomass toward the central part of the bay.

Forecast of the maximum thickness of ice deposits

R.Yu. Ignatov1,2, K.G. Rubinshtein1,2,3, Yu.I. Yusupov2
1Nuclear Safety Institute, Russian Academy of Sciences, Moscow, Russia
2Limited Liability Company Scientific Production Association «Map Maiker, Moscow, Russia
3Hydrometeorological Centre of Russia, Moscow, Russia
Keywords: glazed frost, estimates of maximum thickness of ice deposits, numerical weather forecast model WRF-ARW

Abstract >>
He methods and results of numerical prediction of the maximum thickness of ice deposits are described. The success of ice deposition forecasts is estimated from calculations based on the WRF-ARW model output for different Russian regions.

Algorithm for a control of ozone lidars photon counter

A.A. Nevzorov, A.V. Nevzorov, A.I. Nadeev, N.G. Zaitsev, O.A. Romanovskii
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: program, lidar sensing, ozone, photon counter, data processing

Abstract >>
An algorithm is developed and, on its basis, a software product is created to control the photon counter and to save the data from recording system of the lidars receiving channel at wavelengths of 299/341 nm in atmospheric sensing with a spatial resolution from 1.5 to 150 m. The main software options are: device connection check; receiving lidar sensing data; data digitization; graphical displaying; data filing; conversion of .dat into .txt file format. The software product is experimentally tested along with the mobile ozone lidar receiver unit, incorporated into the software part of the measurement complex of the Siberian Lidar Station. The receiver unit of the mobile ozone lidar comprises a photon counter PHCOUNT_4 and Hamamatsu photoelectronic multipliers H12386-210. We present the atmospheric lidar sensing data and an ozone concentration profile retrieved in 2022.

Errors of pure rotational Raman lidar absolute calibration due to collisional line broadening

V.V. Gerasimov
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: Raman scattering, lidar, spectral line broadening, lidar calibration, tropospheric temperature

Abstract >>
The effect of collisional line broadening on the accuracy of tropospheric (0-11 km) temperature measurements with pure rotational Raman (PPR) lidars at their absolute calibration by spectroscopic parameters was estimated via numerical simulation. The simulation was performed for five sets of spectral filters (SF) with different passbands in a lidar spectral selection unit and an outgoing laser signal wavelength of 355 nm. It is shown that the unavoidable absolute calibration error can reach values from 0.14 to 0.44 K (depending on the SF set) when ignoring the N2 and O2 PRR line broadening. The line broadening can be neglected if only one PRR line is extracted in each of the two lidar channels (for example, using a Fabry-Perot interferometer).