Home – Home – Jornals – Chemistry for Sustainable Development 2021 number 5

At present, the most complete theoretical list of H₂O monomer absorption lines is the POKAZATEL data bank, which contains H₂O lines up to energy dissociation ~ 40000 cm^-1 (0.25 mm). The atmospheric transmission of ultraviolet (UV) radiation is simulated with use of H₂O lines from the POKAZATEL. The broadening parameters of the absorption lines are defined more accurately with use of different approximations in the UV region. It is shown that the H₂O absorption lines contribution to the atmospheric transmission can reach 0.03 near 25000 cm^-1 at a spectral resolution of 0.01 cm^-1.

Information about an angular distribution of emission from the filamentation region is required to select an effective scheme for remote sensing of the aerosol atmosphere by femtosecond laser-induced breakdown spectroscopy. We present the results of a series of experiments on identification of an impurity with the use of femtosecond LIBS. The angular distribution of the emission from the femtosecond radiation filamentation region in the atmosphere for an impurity in water aerosol is estimated in the range from 0 to 180° based on the experimental data. A model of the angular distribution of the emission is suggested, where absorption in the filament plasma is taken into account. The variation in the intensity of the emission line with the impurity concentration is analyzed. It is shown that emission from the filamentation region occurs due to spontaneous emission.

The quantitative and physico-geochemical characteristics of particulate matter in the winter atmosphere of Yakutsk, accumulating in the solid phase of the snow cover, are examined. Snow survey was carried out on the territory of the city in 2020. Based on modern methods of analysis the features of the transformation of the chemical composition of particulate matter in the winter atmosphere of an urbanized territory are analyzed. The main source of pollution of the winter atmosphere of the city is motor transport; energy facilities and industrial enterprises contribute less. The features of the macro- and microelement composition of the solid phase of snow on the territory of the city have been ascertained. The intensity of the intake of chemical elements with winter dust varies within 6-7 mathematical orders: from a maximum of 103-104 mg/(m² × day) for Ca, Fe, and Al, to a minimum of £ 10-3 mg/(m² × day) for Pt, Au, and Hg. The most unfavorable from a sanitary point of view is the fallout of Fe, Zn, and As from the winter atmosphere. Heavy metal pollution of the snow cover on the territory of Yakutsk is noticeably lower than in a number of cities in Eastern Siberia.

A method has been developed for determining the turbulent energy dissipation rate, the dispersion of the radial velocity and the integral scale of turbulence from the spectral density of the vertical wind velocity measured by a pulsed coherent Doppler lidar. To obtain unbiased estimates of these wind turbulence parameters, the averaging of the radial velocity over the probed volume is taken into account. The method has been tested in a numerical experiment. An algorithm is proposed for calculating the error of the lidar estimates of the dissipation rate obtained by this method.

In order to test a new method for determining the parameters of wind turbulence from the spectra of the vertical component of the wind speed vector measured by a pulsed coherent Doppler lidar (PCDL), in the summer of 2020 we conducted an experiment on the territory of the Basic Experimental Observatory (BEO) of the IAO SB RAS. A comparative analysis of the estimates of the turbulent energy dissipation rate obtained by two methods: 1) from the spectrum of the vertical component of the wind velocity vector (new method) and 2) from the azimuth structure function of the radial velocity measured by a conically scanning PCDL (previously used method) showed that the new method also gives an unbiased estimate. The results of lidar measurements of wind turbulence parameters in the presence of a low-level jet stream and an internal gravity wave in the atmospheric boundary layer are presented.

The results of statistical simulation of the albedo and diffuse transmission of the atmosphere in the visible region in the presence of overcast and broken cirrus clouds are presented. The main numerical experiments were performed using the third version of the model proposed by a group of authors consisting of B.A. Baum, P. Yang, A.J. Heymsfield et al. (a mixture of particles of different shapes and sizes with a rough surface). To assess the effect of random geometry of clouds on the solar radiation transfer in the atmosphere, G.A. Titov method of closed equations, developed within the framework of a model based on Poisson fluxes of points on straight lines, was used. Analysis of the influence of the microstructure of cirrus clouds on the mean albedo and diffuse transmission at average cloud fraction showed that the average value of the uncertainty due to the lack of information on the particle shape and size is within ~ ± 2%. This value is comparable to the effect of random geometry effects in optically thin clouds, while in optically dense clouds the range of errors caused by ignoring the horizontal heterogeneity increases and is ~ ± 5% in albedo calculations with an underestimation of the diffuse transmission by ~ 10-20%.

This influence of assimilation of date from lightning detection networks on the quality of the weather forecast using the numerical model is analysed. For 10 dates of 2020 over the Krasnodar Territory, estimates of the quality of forecasts for some meteorological parameters were calculated: without lightning assimilating; with assimilation of data from global and regional networks separately; with assimilation of data from all networks. WRF-LTNGDA was used as the assimilation procedure, and WRF-ARW model ver. 3.9.1 was used as a predictive model. We have studied the influence of information from: WWLLN, GGO, and VGI networks, as well as the new global lightning network TLN.

The application of a method based on artificial neural networks for assessing the total water vapor content in the atmospheric column from data of the MSU-GS satellite instrument of Electro-L No. 3 geostationary spacecraft is considered. The results of comparing the estimates of the total water vapor content from the MSU-GS data with MODIS satellite instrument data and AERONET measurements showed high agreement. The root mean square error when compared with the MODIS data was 0.311 cm, with the AERONET data, 0.409 cm, and the correlation was 98.2% and 84.7%, respectively. The results indicate the effectiveness of the method for determining the total content of water vapor for solving problems of atmospheric physics.

A review of methods for calibrating optical raingauges is carried out. The disadvantages of the existing calibration methods of the optoelectronic raingauge OPTIOS are analyzed and the ways to eliminate them are proposed. The original patented method for calibrating the optical raingauge is described in detail, which makes it possible to increase the accuracy of determining the dimensions of hydrometeors by taking into account the effective size of each photosensitive element of the linear sensor. A conclusion is made about the reliability of the proposed calibration method, which makes it possible to use the method to improve the accuracy of any optical meters of linear dimensions of various objects using a linear array of photosensitive elements as a measuring transducer.

The joint influence on the systematic error of sonic temperature measurements of the unaccounted time delay of signal transmission between sound transmitter-receiver pairs and temperature changes in the distances between them is considered. Analytical relations for estimating the considered error and the results of its calculations are given. The method of calibration of such devices in a climate chamber with the use of reference measuring instruments is described, which allows one to reduce this influence by more than an order of magnitude in the range of measured temperatures from -70 to + 50 °C.

The process of second harmonic generation (SHG) of laser radiation in a BBO crystal is theoretically studied with the aim of determining optimal values of focusing and wave detuning parameters providing maximal SHG efficiency. This optimization problem is solved under an additional condition, that is, the maximal radiation power density should not exceed an a priori specified value. No restrictions are posed on the radiation power. The study consists of two parts. In the first part (this work), the influence of this additional condition on the process and results of solution of the optimization problem is studied with the use of the preset field approximation. Due to the additional condition, optimal focusing and wave detuning parameters become dependent on the radiation power, but the algorithm of solution of the problem becomes noticeably simpler, which allows the computation time to be significantly reduced, by about an order of magnitude.

The possibility of phase transitions (martensitic transformations) in shape-memory alloys is evaluated using the concept of eigenmoduli and eigenstates from the linear theory of elasticity. For alloys with cubic and hexagonal lattices, the matrices of elastic moduli and compl are given and expressions for their eigenmoduli and eigenstates are written. For cubic and hexagonal phases, the specific strain energy is presented as the sum of six independent terms corresponding to six orthogonal eigenstates. It is shown that depending on the ratio of eigenmoduli, there are six types of materials (alloys) with cubic and hexagonal symmetry. The specific strain energies in the cubic and hexagonal phases are compared. If the strain energy is greater in the hexagonal phase than in the cubic phase, the alloy can tend to return to its original state with lower energy. In addition, the strain energies in different phases can be compared using the formulas of the tensors closest in the Euclidean energy norm to cubic and hexagonal tensors. The energies are compared for some values of elastic constants.

For boundary-value problems, the Helmholtz equations in wedge-shaped domains, it is shown that in packed block elements corresponding to the same boundary-value problem can be combined taking into account the type of boundary conditions, also forming a packed block element. The result is verified using another method. It is shown that in the presence of corner points in the domain in which the boundary-value problem is considered, combining block elements does not involve additional complications. It is found that since the solutions of some boundary-value problems in continuum mechanics and physics can be represented as a combination of solutions of boundary-value problems of the Helmholtz equation, this approach can be used to study more complex boundary-value problems and design materials with mosaic structure.

Interaction between a thin viscoelastic layer and a rigid cylinder whose contacting end surface is nominally flat but has a microrelief is studied. The microrelief is modeled by a periodic system of axisymmetric indenters. Analytical expressions for the depth of indentation and the actual contact area are obtained using an approach based on consideration of micro- and macroscale levels. The effect of the surface microgeometry of the punch and mechanical properties of the layer on the time dependences of the indentation depth and the actual contact area.

A self-balanced stress field for an incompressible sphere is constructed based on a non-Euclidean model of a continuous medium. The total stress field is presented as the sum of the elastic and self-balanced fields. The requirement that there are no singular contributions to the stress field leads to the fact that the coefficients at the singularities of the elastic and self-balanced stress fields can be related by a linear transformation, ensuring the removal of singularities. The compensating role of self-balanced stress fields allows one to construct a nonsingular equilibrium stress field for a spherically symmetric state of a continuous medium.

A problem of damping vibrations of a smart structure consisting of elastic and viscoelastic materials and piezoelements with connected shunt circuits is considered. It is proposed to replace the classical resistor in the shunt circuit by an element made of an electroconducting material, in particular, a polymer material filled with graphene nanoparticles. This element plays the role of several resistors with different resistance values, which ensure multimodal damping of vibrations. A mathematical formulation of the problem of forced steady and natural vibrations of smart systems under consideration is provided, as well as results of numerical calculations, which show that graphene-based composites can be used for additional damping of vibrations of smart structures based on piezoelements.

Results of theoretical and experimental investigations of physical and mechanical properties of a heterogeneous material based on the TiB ceramics and VT-6 metallic alloy obtained by means of controlled laser processing are reported. Elastic properties of the heterogeneous structure under analysis are described by the method of conditional moments. Young's modulus of the created heterogeneous material cased on the titanium alloy and titanium boride is measured. The experimental data are found to be in good agreement with the numerical predictions.

Results of the analysis of elastoplastic deformation of a rotating solid cylinder with fixed end faces under monotonic loading by centrifugal forces are reported. The theory of small elastoplastic strains is used in formulating the problem. The general piecewise-linear condition of plasticity and the associated law of the flow are used for calculating the plastic component of the strain. The chosen plasticity condition depends on the parameter that can be considered as a material characteristic. An exact solution of the governing system of equations is derived. Regular features of plastic flow development are found. It is demonstrated that six plasticity domains are formed in the cylinder in the general case; these domains correspond to different ribs and faces of the surface defined by the general piecewise-linear condition. The dependence of the critical velocity of cylinder rotation on the parameter included into the plasticity condition is derived.

A method is proposed to control the properties of thin ferroelectric films under forced deformation due to the size mismatch of the crystalline lattices of film and substrate materials and due to the difference of their thermal expansion coefficients. Control is based on additional mechanical deformation of the substrate. A model of a single-crystal Ba_xSr_1-xTiO₃ film is studied within the framework of phenomenological theory using the Landau potential. It is shown that additional uniaxial deformation of the substrate in a Ba_xSr_1-xTiO₃ film changes the material constants of the film. Abnormal change occurs at deformation values close to the values at which the phase state of the film changes. The generation of surface acoustic waves is studied. The results of modeling simulations indicate the possibility of controlling the excitation of surface acoustic waves in the film-silicon substrate heterostructure.

A mathematical model of large deformations is used to solve a coupled boundary-value problem about the deformation of an elastic-viscoplastic material in a cylindrical viscometer with account for its heating due to wall friction. The deformation of a material enclosed between rigid surfaces due to the rotation of an inner cylindrical surface at a variable velocity is investigated. It is taken into account that a yield point depends on temperature. The motion of elastoplastic boundaries is described. Stresses, strains, and temperature in a thermoelastic deformation region and in a flow region both during the development of the flow and during its deceleration, including stopping, unloading, and cooling, are calculated. Residual stresses and deformations are determined.

A model of dynamic deformation and fracture of composite materials is been developed. This model accounts for the significant nonlinearity of shock loading diagrams with hardening, which depends on strain rate. An approach is used in which the dependence of ultimate strength on damage parameters and their variation rate is introduced in the form of constitutive relations. The proposed relations are similar to those of the Johnson-Cook model, but stresses are expressed via damage parameters and their variation rate rather than in terms of plastic deformations and the variation rate of plastic deformations. On the basis of the developed model, the impact fracture of a tubular profile made of a composite material based on carbon fiber and a polymer binder are numerically simulated. The influence of the orientation of unidirectional layers of a composite on specific absorption energy is investigated.

A problem of the projectile impact onto a membrane is studied under the following assumptions: the armor shell is a membrane with a zero flexural stiffness and a large Young's modulus under tension; the frontal part of the projectile is shaped as a paraboloid; the projectile impact onto the membrane is considered in a quasi-static formulation; the membrane is broken when a certain limiting surface tension is reached at the paraboloid vertex. It is found that the armor shell ensures safety if the kinetic energy of the projectile does not exceed some maximum value for this armor determined theoretically or experimentally.

We have investigated a class of materials whose experimental stress-strain behavior does not allow them to be considered plastic or elastic. They are not elastic since unloading occurs along a curve significantly different from the loading curve; nor are they plastic since in a full loading-unloading cycle, residual deformations are absent. As such materials we investigate so-called metal rubbers - materials made from twisted wire pressed into an almost homogeneous body. The propagation of shock waves in these materials is studied using a one-dimensional model.

A stress-strain state arising under dynamic tension of a homogeneous rod made of an incompressible ideally rigid-plastic material that satisfies the Mises-Hencky criterion is investigated. The possibility of thickening or thinning of the rod along its length is taken into account in an axisymmetric formulation, which makes it possible to simulate the formation and development of a neck. Three dimensionless time functions are introduced, one of which is a small geometric parameter, namely the ratio of an average radius to half the rod length. The ratios of the orders of smallness of the other two dimensionless functions to the small geometric parameter determine the influence of inertial terms in equations of motion on the stress and strain rate distribution. These ratios may vary at different time intervals, which determines one or another dynamic tension regimes. Two such characteristic regimes are revealed: one of them depends on a velocity at which the end sections move away from each other, and the other one depends on their acceleration. For the second regime, an asymptotic integration based analysis makes it possible to find the stress-strain state parameters, in which case this state is an “inertial correction”' with respect to a quasistatic state in the rod with a cylindrical lateral surface.

Results of solutions to problems of determining the parameters of anisogrid lattice structures of spacecraft bodies are presented. These problems include analyzing the deformability of a body loaded with transverse inertial forces, determining the fundamental frequency of transverse vibrations of a cantilevered body, studying the deformability of a body loaded with axial compressive force, and analyzing the deformability of a body with an internal fuel tank loaded with transverse inertial forces. The problems under consideration are solved using a continuous model of the lattice structure of a cylindrical body and the finite-element method.

A method is proposed for constructing variational models of continuous media for reversible and irreversible processes based on the generalized Hamilton-Ostrogradskii principle, which reduces to the principle of steadiness for a non-integrable variational form of a spatial-temporal continuum. For dissipative processes, the corresponding linear variational form is constructed as a sum of variation of the Lagrangian of the reversible part and a linear combination of dissipation channels of physically nonlinear processes. Examples of using the variational approach to the description of hydrodynamic models are considered. The corresponding variational models of the Darcy hydrodynamics, linear Navier-Stokes hydrodynamics, Brinkman hydrodynamics, gradient hydrodynamics, and some generalization of the classical nonlinear Navier-Stokes hydrodynamics are constructed. For modeling irreversible processes of hydrodynamics with allowance for coupling of deformation with the associated physical processes of heat transfer, it is proposed to use variational formalism for the spatial-temporal continuum, where the spatial and temporal processes are considered simultaneously and consistently because the normalized time is a coordinate.

Results of an experimental study of the strength characteristics and structural-phase composition of a nondetachable connection of disparate materials based on thermally hardened aluminum alloys D16T of the Al-4,4Cu-1,5Mg system and 1420 of the Al-5,2Mg-2,1Li system obtained by butt-end laser welding are reported. The phase composition of the welded joint is studied with the use of synchrotron radiation by the method of transmission diffraction. The welded joint microstructure is considered by optical microscopy. It is demonstrated that heat treatment (quenching and artificial aging) allows one to improve the chemical properties of the welded joint.

The finite element method is used to develop a computational algorithm for solving a limited class of problems on the bending of composite plates reinforced with systems of unidirectional high-strength fibers. It is assumed that a neutral plane exists in the region of the plate and behaves similarly to a flexible nondeformable membrane. The displacements of the plate in the longitudinal direction are linear in thickness. In the case of fiber composites of different modulus with different elastic properties under tension and compression, the neutral plane, generally speaking, does not coincide with the median plane. The problem of minimizing the elastic energy functional in accordance with the Lagrange variational principle yields a fourth-order elliptic differential equation for the deflection. The bending stiffnesses of the plate included in the coefficients of the equation are calculated with account for the fact that the elastic characteristics of the reinforcing fibers under tension and compression are significantly different. The numerical solution of the equation is obtained via the finite element method with the help of a Bell triangular element. The paper presents computational results for the bending of rectangular laminated plates in which the fibers are laid in different directions.

A mathematical model has been developed for calculating the relaxation of residual stresses in a surface-hardened prismatic sample in creep under biaxial loading. The calculation results were verified against experimental data for a surface-hardened sample of EP742 alloy after ultrasonic hardening under creep conditions at a temperature of 650oC for 100 h. A detailed theoretical analysis of the influence of the type of stress state on the relaxation of residual stresses during thermal exposure (temperature exposure in the absence of mechanical stress) and under biaxial loading at a constant intensity of external stresses was performed. It is shown that under uniform tension in a plane stress state, the relaxation of residual stresses slows down, and under compression, the relaxation rate increases compared to the case of thermal exposure.

A microstructural model of behavior of ferromagnetic material (Heusler alloy) in a magnetic field is constructed within the framework of the theory of micromagnetism. The process dynamics is described by the Landau-Lifshitz-Hilbert equation. The Galerkin procedure is used to assign variational equations to differential relations. A “Christmas Tree” type martensitic structure (twinned version of martensite) with magnetic domains arranged at an angle of 180oC is considered. The twin boundaries act as 90-degree magnetic domain walls. The evolution of this magnetic structure is investigated, namely the motion and interaction of the 180-degree walls of this magnetic domain in the presence of an external magnetic field applied in different directions. The finite element method simulates the formation of these walls and the magnetization vector distribution in them.

The problem of constructing exact solutions of the von Mises three-dimensional plasticity equations based on the group of continuous transformations admitted by the equations (Annin's problem). New classes of solutions of the three-dimensional plasticity equations are given. The problem of compression of an elastoplastic material layer by rigid plates is solved. In this case, the material obeys the exponential plasticity condition, proposed by Annin.

The samples of humic preparations (HP) containing macro- and microelements of plant nutrition were obtained on the basis of humic acids (HA) isolated from brown coal of the Tisul deposit of the Kansk-Achinsk coal basin. The biological activity of humic preparations was tested under laboratory and field conditions on stony and loamy soils using the seeds of high-quality wheat varieties ‘Iren’ and ‘Novosibirskaya 89’. A comparative assessment of the influence of the content of microelements cobalt, manganese, copper and zinc in humic preparations on the growth parameters of wheat was carried out. It is shown that the effectiveness of the use of humic preparations depends on the concentrations of all components, the method of their introduction, as well as on the edaphic properties of soil substrates.

The granulometric and morphological composition of fine coal powders prepared according to a special technique for the size classes -0.2 +0.1, -0.1 +0.063, -0.063 +0.04, -0.04 mm from ten different grades of coal (B, D, G, Zh, K, KS, OS, SS, T, A) of the Kuznetsk coal basin was investigated. Technical and elemental analysis, petrographic studies were carried out with the coal samples using standard methods. The set of values of the reflectivity of vitrinite, the sum of the fusenized components, the thickness of the plastic layer and the yield of volatile substances allowed us to establish the grade identity of the studied samples in accordance with the unified classification of coals on the basis of genetic and technological parameters. According to the results obtained by SEM, changes in the structure of coals and the relief of the fracture surface pattern are observed in the series of metamorphism of the studied coal samples from brown coal to anthracite. The granulometric composition of coal powders was determined by laser diffraction when the samples were dispersed in an aqueous medium with the addition of a surfactant. The particle size distribution in coal powders of the fraction -0.04 mm for all grades of coal is characterized as monomodal, in the fractions -0.063 +0.04 mm - as monomodal asymmetric, in fractions -0.1 +0.063 and -0.2 +0.1 mm - as bimodal. These fractions contain irregularly shaped particles (needle-shaped, oval), as determined by means of SEM. According to the results of the studies of KS grade coal by means of NMR spectroscopy, it is established that the content of aliphatic carbon (CH₃) in the samples increases insignificantly with a decrease in the size of the coal powder fraction - from 3.05 % for the fraction -0.2 +0.1 mm to 3.73 % for the fraction -0.04 mm. The values of the aromaticity index f _a for all fractions remain constant.

Features of phase formation and properties of solid solutions in the nanostructured FePt system synthesized by reducing the aqueous solutions of precursors by hydrazine hydrate are considered. It is established by means of X-ray diffraction studies and elemental analysis involving optical emission spectroscopy that limited solid solutions with the fcc type structure are formed under the conditions of the samples with the component ratio Pt/Fe ≥ 0.5. With iron content ( С _Fe) ≤ 11.6±0.7 at. %, the system is monophase (an fcc-solid solution), with higher iron content it is composed of two phases (an fcc-solid solution with С_Fe = 11.6±0.7 at. % and a diffraction-invisible phase relatively enriched with iron). The size of the coherent scattering region for the solid solution varies from 7 to 9 nm. The presence of Fe³⁺ was revealed in all samples by means of electron paramagnetic resonance. Small amounts of iron hydroxide and oxides were detected by means of XRD in the samples with a high iron content. The temperature regions of O₂ and CO₂ desorption, thermal decomposition of extrinsic FeO(OH) and crystallite agglomeration accompanied by phase transformations were determined in the studies of thermally stimulated processes.

A retrospective analysis of the results of studies of the mechanism of water migration in freezing soils was carried out on the basis of an analysis of about 160 scientific publications by Russian and 100 foreign authors. For the analysis, articles, monographs, dissertations, patents, conference proceedings and scientific reports were used. The main ones are given in the list of references. Special attention is paid to the key aspects of the formation of understanding of the driving forces of cryogenic migration (moisture transfer) in freezing soils. This analysis is necessary for the correct physical formulation of the mathematical model of the process of frost heaving of freezing soils.

The paper analyzes the current temperature state of frozen and thaw soils in the Baikal region (Olkhon Island). It has been demonstrated that the current trend in soil temperature is directly related to climate changes and to the increase in the atmospheric air temperature. Permafrost within Olkhon Island is significantly transformed: the processes in soils are aimed at the degradation of frozen strata.

The paper presents the data on maximal extent of the East Siberian fast ice and its variability based on Arctic and Antarctic Research Institute operational sea ice chart for the period from 1999 to 2019. The maximal fast ice extent were compared to the ERA5 reanalysis local winds. The analysis of the maximal landfast ice variability showed no statistically significant changes between 1999 and 2019. Two typical configurations of fast ice edge were revealed for the winter month characterized by the maximal fast ice extent. In some seasons fast ice development stops once the edges reaches 20 m depth, while in other season the fast ice edges advances to 30 m depth. The maximal fast ice extent is reached during the seasons with prevailing northerly and north-easterly winds. The onshore wind favours sea ice deformation and grounding at the seaward fast ice edge.

As the direct measurements for the mass balance estimation can be applied only for a limited number of glaciers, alternative methods of estimation need to be developed. One of the most promising approaches is physically-based modelling, that is now being applied globally. In this study the mass balance of the Sary-Tor valley glacier was reconstructed for the period of 2003-2016. Originally developed for the North Caucasus A-Melt model was modified to fit the conditions of continental glaciers. A block of snowpack processes was added to the model, including: head conductivity in the snowpack and in the active layer, water filtration in the snowpack and firn, congelation and regelation. The modelling results were verified using: 1) direct measurements on the ablation stakes net; 2) mass balance estimation according to geodetic method. The calibration parameters are compared to their measured values. Contrasting modeled mass-balance components for 2003-2016 and measured in 1985-1989 provided possibility to reveal climatically induced change of the Sary-Tor glacier dynamics.

Interferometric pairs of ALOS PALSAR dataset (2007-2010) were used to estimate the seasonal and long-term variations in the ground surface height in the piedmont of the Polar Ural, the far northeast of European Russia. The obtained results were validated by ground-truth measurements at the CALM R2 site (the site of monitoring the thickness of the active layer). The values and amplitude of ground surface height variations obtained from the satellite imagery were lower compared to field measurements. The sites under study were classified in two conditional groups: more drained sites (confined often to the upper parts of the moraine ridges) and sites with higher moisture content in the soil (lower parts of the slopes). This classification was based on the intensity of seasonal changes in the height of ground surface during the vegetation period of 2007. Significant correlations between the compared in situ and remote sensing-based measurements were established for these groups. The convergence of the results increased with a greater number of in situ measurements inside the pixel of the satellite image. The greatest differences in the magnitude of changes in the height of ground surface were reported in years marked by contrasting weather conditions (2007 and 2010). Ground surface subsidence was reported to be greater (up to 1.5-4.5 cm) during the colder and wetter vegetation period of 2010, and less pronounced in a drier and warmer season of 2007 (0.0-3.0 cm) within tundra zones of the Pechora Lowland. A summer ground surface heave was noted (up to 2-3 cm) in sites with moraines deposits in the piedmont plains for the whole period of observations.

This article analyses the results of Loza-B georadar sounding of the upper part of the permanently frozen ground section in the area of polygonal microrelief development. These investigations took place on the eastern coast of the Taymyr Peninsula and on the western coast of Kotelny Island (New Siberian Islands). The polygonal microrelief is at the descend stage of development at both sites, so the ground-penetration radar profiles were scanned across the flat and high-centered central parts of the polygons. The results allowed us to determine some peculiarities of ground-penetration radar profiles for polygons with different types of surfaces, composed mainly of sand-gravel deposits. Typical ground-penetration radar complexes corresponding to the central parts of the polygons and deposits overlapping thawed ice wedges were identified. The possibility of using the spectrum of waveforms to interpret results was shown, velocities of electromagnetic wave propagation in the studied deposits were determined. Ice wedges and pseudomorphs after them were not reliably identified, but areas of their possible location were.