Turbulence spectra and turbulence scales were measured with the AMK-03 acoustic meteorological station and DJI Phantom 4 Pro unmanned aerial vehicle (UAV). The measurements were carried out in the Geophysical Observatory of the Institute of Monitoring of Climatic and Ecological Systems SB RAS, which is located at a territory with complex orography. The turbulence spectra obtained with the AMK-03 and DJI Phantom 4 Pro generally coincide with some discrepancies observed in the high-frequency spectral range starting from Hz. The lateral and longitudinal turbulence spectra in the inertial range obey the “5/3” law, and their ratio corresponds to the Kolmogorov—Obukhov isotropic turbulence. The obtained experimental spectra were approximated by the least square fit method with the von Karman mathematical model. The turbulence scales calculated from the AMK-03 and DJI Phantom 4 Pro findings coincide, and the condition describing the relation between the longitudinal and lateral scales in the isotropic atmosphere is fulfilled.
The paper shows the possibility of using small UAVs with a rotary wing to monitor the state of atmospheric turbulence at different altitudes. The measurements were carried out at the Basic Experimental Observatory (BEC) of the V.E. Zuev Institute of Atmospheric Optics SB RAS. The turbulence spectra at 4, 10, and 27 m, as well as turbulence scale profiles obtained with three DJI Mavic Mini and one DJI Mavic Air quadcopters are reported. The turbulence spectra measured at different altitudes and turbulence scale profiles are compared with the data obtained from three AMK-03 automated meteorological systems installed at the 4-m and 30-m meteorological towers. It has been found that the turbulence spectra obtained with the AMK-03 and quadcopters are generally in a good agreement with some differences observed in the high-frequency spectral region nearby Hz. During the experiment, Kolmogorov turbulence was observed in the atmosphere in a wide frequency range at all altitudes. This type of turbulence was confirmed by both the AMK-03 and quadcopter data. When determining the longitudinal and lateral turbulence scales at altitudes of 4, 10, and 27 m, the least square fit method was used with the von Karman model as the regression curve. The turbulence scales calculated from AMK-03 and quadcopter data are shown to agree well. The condition describing the relation between the longitudinal and lateral scales in an isotropic atmosphere is true to sufficient accuracy.
The description of the developed automatic weather station for the Arctic region is presented. The station provides information to the remote user measured data such as three-component vector of wind velocity, air temperature and humidity, atmospheric pressure, precipitation parameters, solar radiation intensity, snow cover depth, and soil temperature profile (including ground surface temperature). The solution to this problem is possible only through the use of automated systems that can data acquisition, process and transmit meteorological information to a remote user in an automatic mode without human intervention.
The turbulent power spectra of Euler angles are studied. The results of their comparison with the spectra of turbulent fluctuations of wind velocity components in the atmosphere are present. Equations are derived for estimating the horizontal wind components as a function of the means and fluctuation components of Euler angles. Time series of turbulent fluctuations in pitch, roll, and yaw angles, as well as time series of turbulent fluctuations of wind velocity components are obtained during an experiment, which was carried out at Geophysical Observatory of IMCES SB RAS in Tomsk Akademgorodok (Russia). The time series of Euler angles and wind speeds were recorded with a frequency of 10 Hz. The automated weather station data witness anisotropy of turbulent flow speed fluctuations during the measurements in the atmosphere: the spectra of fluctuations of the horizontal components coincide, but differ from the spectrum of vertical fluctuations. The fluctuations of the Euler angles show similar behavior: the spectra of fluctuations of pitch and roll angles coincide, but differ from the spectrum of fluctuations of the yaw angle. The spectra of fluctuations of pitch and roll angles and the spectra of fluctuations of the horizontal wind velocity components generally coincide, though differences are observed in the high-frequency region of the spectrum. In contrast to fluctuations of pitch and roll angles, the spectrum of fluctuations of the yaw angle coincides with the spectrum of the vertical wind velocity component in the high-frequency region.
A multi-position complex consisting of three automatic weather stations TAA-01 carried out pilot measurements of meteorological, actinometric, and atmospheric-electrical quantities at extremely low temperatures. The state of atmospheric surface layer during heavy frosts caused by the invasions of arctic air mass in winter was analyzed.
The paper discusses the conditions of the “Squall” natural hazard emergence, registered in the end of October 2018 in Tomsk. Meteorological values dynamic specifics are described before and during that phenomenon, based on IMCES measurement-computational system data.
The paper suggests an approach for cumulonimbus clouds detection, including embedded convection, based on threshold values of surface atmospheric electric field potential gradient. On the example of IMCES SB RAS (Tomsk) measuringcomputation system, authors demonstrate the effectiveness of such approach implementation for real-time information obtaining on submerged convection in frontal cloud fields.
The results of measuring the vertical profiles of the main meteorological quantities in the atmospheric boundary layer to an altitude of 1000 m by the ultrasonic weather station AMK-03, placed on the suspension of a tethered balloon during its ascent and descent are presented in the article. Recommendations on the procedure for performing measurements using an ultrasonic weather station based on a tethered balloon are suggested.
Variations in the electrical characteristics of the surface layer of the atmosphere during the passage of cumulonimbus clouds (Cb) and the accompanying atmospheric phenomena (snow showers, drifting/blowing snow) in the cold season have been investigated. The statistical characteristics of electric field potential gradient values during the passage of winter Cb are estimated. Comparison of the potential gradient values during the passage of Cb in the warm and cold seasons are compared.
The article describes a software system intended for supporting scientific researches of the atmosphere during the processing of data gathered by multi-level ultrasonic complexes for automated monitoring of meteorological and turbulent parameters in the ground layer of the atmosphere. The system allows to process files containing data sets of temperature instantaneous values, three orthogonal components of wind speed, humidity and pressure. The processing task execution is done in multiple stages. During the first stage, the system executes researcher’s query for meteorological parameters. At the second stage, the system computes series of standard statistical meteorological field properties, such as averages, dispersion, standard deviation, asymmetry coefficients, excess, correlation etc. The third stage is necessary to prepare for computing the parameters of atmospheric turbulence. The computation results are displayed to user and stored at hard drive.
The multilevel ultrasonic complexes created in IMCES SB RAS for automatic monitoring of meteorological and turbulent parameters in the ground atmosphere are described in this article. The results of measurements which demonstrate their opportunities for scientific research of the atmosphere are given in this article as well.
Nowadays the sources of long-wavelength optical radiation (far infrared, terahertz range) are developed intensively. They have good perspectives in different fields of biology, medicine, security systems etc. This implies the need to have the detectors of radiation with advanced parameters 1,2. Golay cell 3 is one of the most sensitive detector types available at the time being despite, the strong development of semiconductor detectors 4 – 6. In Golay cell the energy is measured by the expansion of the gas in the sealed chamber: the gas absorbs the energy and presses the flexible membrane, thus the change of volume is registered. The disadvantages of these detectors are relatively high price, big size and vibration susceptibility. In our paper we consider the method of radiation detecting that is similar to one that is used in Golay cell but based on gas temperature measurement.
Conception of design of measuring and computing system for monitoring atmospheric boundary layer is proposed. The system includes: stationary measuring complex consisting of four multiple-elevation ultrasonic weather stations and mobile measuring complex consisting of transportable weather station, touch probing system of weather data profile based on unmanned aerial vehicle and also Raman scattering gas analyzer, and new modification mercury gas analyzer.
Formation of stable micro-protrusions and microstructures ("microtowers") on surface of liquid metals during
multipulse irradiation by UV and IR lasers in different ambient gases was discovered. The rates of the structure
formation have been measured which can reach 5 - 20 μm/pulse depending on the metal and ambient gas sort. Single
micro-protrusions 1-2 mm in length were formed with diameter approximately two times greater than the focal spot
size. The possibility to control the microstructure shape is shown and their potential applications are demonstrated.
We report a new phenomenon, formation of microstructures, observed at multipulsed nanosecond laser ablation of liquid
metals (Ga, In, Sn-Pb alloy, Wood's metal). Laser irradiation of liquid metal targets was carried out in a gas chamber
equipped with a heater. In contrast to vacuum conditions or an inert atmosphere when a crater is formed which is healed
after termination of irradiation, ablation in a reactive ambient gas (air, nitrogen, sulfur hexafluoride, nitrogen trifluoride)
leads to a horn-like structure growing on the irradiated surface with the rate of 3-20 μm per pulse depending on laser
fluence and the types of metal and ambient gas. The interplay between different processes in a heat-affected zone of the
irradiated samples is analyzed, including ablation, thermal expansion, temperature variations of viscosity, surface
tension, thermal stresses, capillary and plasma effects, and surface chemistry. A clear picture of microstructure origin has
been established and a qualitative modeling representation is given to explain the growth process of microstructures. The
optimal conditions of microstructure growth have been determined and perspective applications of the discovered effect
are discussed.
Experimental and theoretical studies on laser ablation of polymers (PMMA, polyimide) have been performed in a wide
range of CO2-laser fluences. Evolution of polymer laser plume in air has been investigated with simultaneous
registration of radiation spectra of the ablation products, spatial dynamics of plasma flare, and temporal behavior of
plasma emission on separate spectral lines. It has been found that spectral lines have intensity peak after laser pulse
termination while plasma emission spectra are similar to those of organic material combusting. The results confirm that
combustion of the laser-vaporized polymers occurs in the plasma plume. A thermo-chemical model of heating and
ablation of organic polymers by CO2 laser pulses has been developed which takes into account attenuation of radiation in
laser plasmas and chemical processes leading to heating the plume of the ablation products. Temperature evolution in the
irradiated sample, ablation dynamics, and laser beam attenuation are analyzed. The modeling results are compared with
the experimental data on high-speed imaging of the plasma plume. The effect of the formation of a "plasma pipe" is
revealed under polymer ablation in air under normal conditions.
Laser and discharge parameters in mixtures of rare gases with halogens driven by a pre-pulse-sustainer circuit technique
are studied. Inductive energy storage with semiconductor opening switch was used for the high-voltage pre-pulse
formation. It was shown that the pre-pulse with a high amplitude and short rise-time along with sharp increase of
discharge current and uniform UV- and x-ray preionization allow to form long-lived stable discharge in halogen
containing gas mixtures. Improvement of both pulse duration and output energy was achieved for XeCl-, XeF-, KrCl-
and KrF excimer lasers. Maximal laser output was as high as 1 J at efficiency up to 4%. Increase both of the radiation
power and laser pulse duration were achieved in N2-NF3 (SF6) and He-F2 (NF3) gas mixtures, as well.
Laser and discharge parameters in mixtures of rare gases with halogens driven by a pre-pulse-sustainer circuit technique are studied. Inductive energy storage with semiconductor opening switch was used for the high-voltage pre-pulse formation. It was shown that the pre-pulse with a high amplitude and short rise-time along with sharp increase of discharge current and uniform UV- and x-ray preionization allow to form long-lived stable discharge in halogen containing gas mixtures. Improve of both pulse duration and output energy was achieved for XeCl-, XeF- and KrF excimer lasers. Maximal laser output was as high as 1 J at intrinsic efficiency up to 4%. Increase of radiation power and laser pulse duration were obtained in N2-NF3 (SF6) and He-F2 (NF3) gas mixtures, as well.
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