Home – Home – Jornals – Combustion, Explosion and Shock Waves 2026 number 2

The results of a numerical study of laminar fluid flow and heat transfer in an annular gap between two cylinders with a rib on one of the walls are presented. A mechanism for intensifying heat transfer between two cylinders, when one is rotating, was studied. Intensification was achieved by installing a single rib on the inner or outer cylinder. The rib was oriented along the annular system radius and occupied half the height of the gap between cylinders. The problem was formulated in two dimensions. The Reynolds number was varied in the range from 100 to 1000. Air was the working medium. Four options for the location of the intensifying rib were considered. A fundamental difference in the structure of the recirculation zone was noted for different rib locations. Maximum heat transfer was achieved on the wall of the stationary cylinder opposite the rib mounted on the rotating cylinder. Its multiple increase was observed compared to the case of rotating smooth cylinders.

This paper examines interaction of propagating waves with gas bubbles contained in liquid and the behavior of gas bubbles in a gas-liquid mixture. A description of the experimental setup for studying the influence of a propagating wave on gas bubbles is presented and the observed phenomena are described.

The interaction of longitudinal vortices with a turbulent boundary layer and a mixing layer developing in the diffusion zone was experimentally studied. Vortices were generated using jet vortex generators located near the beginning of the model tail unit, forming a diffusion separation. The main measurements were performed using hot-wire anemometry (HWA) and PIV methods. Based on the experimental data, information was obtained on the flow velocity in the pre-separation and separation zones and the dynamic pressure magnitude; the scale of turbulent structures was calculated, and the influence of longitudinal vortices on these characteristics was estimated under various regimes of vortex generator operation. It was found that the effect of longitudinal vortices on the flow leads to a decrease in the separation zone and significantly affects the characteristic scale of turbulent structures.

Investigation results concerning the influence of fuselage and control surfaces deflection on various types of separation that occur in the flow past a swept-leading-edge wing model at subsonic flow velocities in a wind tunnel are presented. This work continues an experimental series on the study of separated flows and the possibilities of flow control around aircraft wing models at low Reynolds numbers. Using proven methods for visualizing the flow near the wing surface and hot-wire measurements, experimental data were obtained that provide a comprehensive understanding of the separation structures that arise on the leeward side of the wing model at various angles of attack and control surface deflections. The issue of flow separation control is also examined. It is shown that global flow separation can be eliminated using the method of local influence at specific points.

To generate a spray flow in confined spaces, specialized nozzles are required to disperse micron- and submicron-sized droplets at the nozzle edge. High-speed visualization of a gas-droplet flow from a custom-made microchannel nozzle device with a resolution of 2.5 μm/pixel was performed, allowing the sizes of the dispersed droplets to be determined. The nozzle device was a custom-made device with a 243 μm thick microchannel silicon membrane and a microchannel size of 10×10 μm². Measurements of the characteristic dimensions were conducted and the velocities of the dispersed droplets were determined at low liquid flow rates (0.05-2 ml/min) and air pressure differences from 1 to 6 atm. At HFE-7100 flow rate of 1 ml/min and an air pressure differential of 1 atm, the average droplet size was approximately 40 μm, while at a flow rate of 2 ml/min and a pressure differential of 2 atm, the average droplet size was 20 μm. A significant increase in velocity was observed with increasing pressure differential. At the minimum flow rate, very small droplets were dispersed, which were not detected at a resolution of 2.5 μm/pixel, but the overall flow was clearly visible as a "mist."

Using the numerical solution of the Navier-Stokes equations, the development of unstable disturbances and the transition to turbulence in a simulated supersonic jet flowing from a circular supersonic nozzle were studied. The simulation was performed in a three-dimensional formulation with resolution of the vortex structure of the flow. The results of numerical simulations were compared with available experimental data.

The transient effects that develop when supplying fresh air to a ventilated space through a jet oscillator were numerically studied. The results of parametric two-dimensional URANS simulations in the Reynolds number range of (5.3 - 53)×10³ showed that with an increase in the supply flow rate, the frequency of self-oscillations of the supply jet increases linearly, while the Strouhal number varies slightly: from 3.3·10^-3 to 5.4·10^-3. The use of an oscillator intensifies air mixing significantly compared to the basic option with a stationary air supply through a slot, which provides almost uniform temperature distribution in the room during cooling.

The results of hot-wire measurements of periodic controlled disturbances of the mass flow beyond the boundary layer on a flat plate are discussed, and their wave characteristics reflecting the acoustic properties of the supersonic boundary layer are estimated. The possibility of emitting subharmonic disturbances at a Mach number of 2.5 is demonstrated for the first time.

A flat methane-air mixture flame was numerically simulated in a longitudinal electric field at various fuel-to-fuel ratios. A computational code developed in the OpenFOAM based on the reactingParcelFoam solver was used for numerical calculations. The results showed that the predicted value of the ion current correlates with the experimental data. The best agreement is achieved in the lean (φ ≤ 0.8) and rich (φ ≥ 1.3) flames. The greatest discrepancy is recorded for the regime of fuel-air equivalence ratio φ = 0.9. The maximum ion current is achieved at φ = 1.1, which corresponds to the experimental results. The obtained data demonstrate the adequacy of the developed code in predicting the flame current value. Calculation data indicate an increase in CH concentration by 20.5% and O concentration by 2.0% when exposed to an electric field; the interaction of these components is the initiating reaction in the formation of charged particles in hydrocarbon flames.

Stationary perturbations of equations of the boundary layer stability are studied for subsonic and supersonic flow past a plate. For two-dimensional perturbations, the results obtained are in good agreement with existing literature data. Three-dimensional perturbations resembling longitudinal structures are studied for the first time. It is established that the amplitude of boundary layer perturbations of longitudinal velocity and temperature has a bell-shaped form, whose maxima position in the Dorodnitsyn-Howarth variables is conservative with respect to changes in the Mach number, Reynolds number, and wave number along the lateral coordinate. Moreover, the intensity of perturbation attenuation along the longitudinal coordinate and the phase shift of the boundary layer perturbation increase with an increase in the above quantities. The largest phase changes are observed for the lateral velocity.

Using a modified mean flux method, a numerical analysis was performed for highly asymmetric scattering phase functions. To solve the radiative transfer equation, the delta-Eddington approximation is used. Radiative-conductive heat transfer in a flat layer of an anisotropically scattering medium was calculated for the Henyey-Greenstein phase function and the transport approximation as an example.

T effect of wettability parameters of a porous heater material on heat transfer during boiling was investigated using a hybrid numerical model based on the lattice Boltzmann method and the heat transfer equation. By simulating the boiling process on a porous heater with a regular hexagonal structure of rectangular metal heat-conducting elements at various thermal heads, boiling curves and coefficients of heat transfer enhancement/degradation were obtained for lyophilic, lyophobic, and neutral heater materials. The results showed that at moderately low thermal heads, the heat transfer coefficient on the lyophobic heater is higher than that for a surface with neutral wettability due to earlier initiation of the vapor phase, while at high thermal heads, heat transfer on the lyophilic heater is the greatest. It was also shown that the temperature of boiling beginning is minimal for lyophobic heaters and maximal for lyophilic heaters, and the boiling crisis does not occur on a porous heater of any wettability even at the maximum heat heads considered.

The problem of ignition and combustion of a region expanding over time is considered. Combustion was initiated using a pulsed-periodic energy source. The influence of pulse frequency and flow velocity on ignition was revealed. Autoignition of a laminar hydrogen jet diluted with nitrogen in a co-current heated air flow was numerically simulated. A transient reacting mixing layer between two flows (air and fuel) with different velocities and temperatures was studied.

Percolation theory is widely used to study heat transfer and other kinetic processes in systems with disordered structures. This paper proposes a phenomenological approach combining methods of percolation theory and multifractal analysis to model a percolation cluster in a three-dimensional infinite medium with multifractal properties. Based on the developed model, unambiguous numerical values for topological critical indices and the critical conductivity index were obtained, previously unknown relationships between critical indices were revealed, threshold conditions that separate qualitatively different regimes of system behavior in the scales of correlation length were determined, and a relationship between the systems order parameter and the golden ratio was established, which indicates the universal nature of the identified dependences.

Percolation theory is widely used to study heat transfer and other kinetic processes in systems with disordered structures. This paper proposes a phenomenological approach combining methods of percolation theory and multifractal analysis to model a percolation cluster in a three-dimensional infinite medium with multifractal properties. Based on the developed model, unambiguous numerical values for topological critical indices and the critical conductivity index were obtained, previously unknown relationships between critical indices were revealed, threshold conditions that separate qualitatively different regimes of system behavior in the scales of correlation length were determined, and a relationship between the systems order parameter and the golden ratio was established, which indicates the universal nature of the identified dependences.

Experimental results on the temperature distribution in a jet of nitrogen flowing from a long pipe into a vacuum under laminar and turbulent flow conditions are presented. A temperature increase downstream was observed under turbulent flow conditions compared to laminar flow conditions. It is concluded that the temperature increase is associated with the turbulent energy relaxation.

Despite numerous studies, many aspects of ignition and propagation of combustion and detonation waves in combustible mixtures remain insufficiently understood, complicating the scientifically sound management of such processes. This paper presents new data on the various stages of ignition and flame front propagation in a flat (two-dimensional) channel of constant cross-section. The experimentally observed main flame instabilities (manifested in the significant non-uniformity and non-stationarity of the combustion front), the phenomenon of flame blowoff (disappearance of glow), and the effect of flame transition to a self-sustaining propagation mode are discussed. Attention is drawn to the problems of the emergence of new ignition sources in the flame front, including explosive micro-sources that facilitate the subsequent transition of combustion to detonation. A number of new features in the physics and dynamics of flame propagation are identified.

Despite extensive research, many aspects of ignition and propagation of combustion and detonation waves in combustible mixtures remain poorly understood, complicating scientifically sound control of such processes. The first part of this paper presented new experimental data on various stages of ignition and flame front propagation in a flat (two-dimensional) channel of constant cross-section. This paper presents results on the little-studied area of combustion wave behavior with changing channel geometric dimensions (so-called flame diffraction). Characteristic processes in the behavior of a turbulent flame as it transitions from a narrow channel to a wide one are established: from flame breakdown and loss of front glow with incomplete combustion of the mixture in a wide channel to the emergence of new explosive microcenters due to the development of expanding flame instabilities and collisions of turbulent flame tongues, leading to the generation of detonation-like waves.

The results of direct numerical modeling of combustion in a cone-shaped methane-air mixture flame directed at a flat, cold barrier are presented. Three cases with different distances between the burner nozzle and the barrier were considered. The study focused on analyzing nitrogen oxide formation in the wall region. It was found that when the barrier was positioned three calibers from the nozzle edge, a recirculation zone with an elevated concentration of nitrogen oxides (NO_x ) forms between the cone-shaped flame front and the cold wall. This increased NOx formation is offset in the downstream wall region.

Using a detailed kinetic mechanism of chemical interaction, the effect of adding ozone (or hydrogen peroxide) and helium as an inert diluent to a stoichiometric hydrogen-air mixture on the detonation wave parameters was numerically studied. It was found that the mole fractions of the additives can be selected such that the detonation wave cell size in the resulting mixture is close to the average cell size in the pure mixture, while the temperature of the detonation products is significantly reduced. It was shown that the introduction of hydrogen peroxide and helium reduces the stability of the detonation wave to disturbances caused by multiple obstacles (barriers) located in the channel, thereby contributing to the wave suppression. Conversely, detonation in a mixture with ozone and helium additives at selected concentrations is found to be more resistant to these disturbances than in the pure mixture.

A microscopic and diffraction study of detonation carbon in the products of benzotrifuroxane-based explosive compositions containing hexogen, octadecanoic acid, and TNT was conducted. Carbon species characteristic of pure benzotrifuroxane were observed in the detonation products of benzotrifuroxane-based compositions with individual benzotrifuroxane granules ranging in size from a few to tens of microns. No such species were detected in the submicron mixture of benzotrifuroxane and TNT.

Wide-range semiempirical equations of state for liquid and gaseous argon, krypton, and xenon are constructed, taking into account evaporation and thermal ionization, based on a modified van der Waals model for mixed substances. The empirical functions that specify the model have a simple form. They contain a small number of free parameters, selected based on the best possible description of the experimental data. A comparison of the model calculation results with experiment up to pressures of ≈1000 GPa and the results of calculations using other models at pressures above 1000 GPa is presented. In the limit of low density and high temperature, the model transforms into an equation of state for a mixture of ideal gases of atoms, ions of all multiplicities, and electrons with a concentration determined by the Saha system of equations.

The possibility of the existence of combustion waves in αCH₄/air gas mixtures and αCH₄/air/coal suspension dual-fuel heterogeneous mixtures (DGMs) with a methane volume concentration of α = 5 ÷ 8% was studied in a closed vertical shock tube and in a horizontal quartz tube open at one end. It was shown that the value of the lower concentration limit of methane flame propagation (LEL) α* and the flame stability are affected by the channel location relative to the gravity vector and the concentration of the coal suspension. In the vertical closed channel, combustion waves propagated from top to bottom in gas mixtures and DGMs at α ≥ 6%, but did not ignite at α ≤ 5.5%. In a horizontal tube, flame propagated in gas mixtures with α ≥ 6% and in a dual-fuel mixture with α ≥ 5.5%. Adding coal suspension to methane-air mixtures has little effect on flame velocity, increases brightness, and reduces the flame's LFL.

The article presents a strategy for empirical-statistical simulation modeling of the organization of forest biogeocenoses as initial objects of terrestrial geosystem monitoring. Spatial functional monitoring of forests is based on empirically established local and regional landscape-ecological relationships, which are considered as mechanisms of metabolic responses of forest geo(eco-)systems to certain climatic trends. This constitutes the novelty of the prognostic empirical-simulation concept of local (and regional) geoecological forecasting developed by the author. The property of polyzonality of local geo(eco-)systems as a way of their response to global climate changes was revealed. An ordination analysis of landscape relationships was carried out based on the main discrete parameters of the biological cycle. A local empirical simulation of the regional bioclimatic trend using the hydrothermoedaphic system of biogeocenoses was conducted, and patterns of transitions of forest communities into critical states were identified. The article describes catenary landscape-ecological structures that form regional systems of localized natural zonality, capable of simulating the main directions and scales of geosystemic restructurings. The landscape-ecological forecast itself is of an experimental nature. It is presented as a system of operations with ecological niches of the objects under study. In computational models, the course of predicted processes is reproduced using their empirical simulation by spatially distributed parameters of basic ecological niches. The basic principle of landscape-ecological forecasting has been formulated, corresponding to one of the provisions of general ecology, namely, the Gause’s law of competitive exclusion. Description of future states of biogeocenotic systems was carried out based on their current spatial organization in accordance with the fundamental properties of ergodicity of the natural environment. Certain time limitations of the empirical-simulation method of landscape-ecological forecasting are noted, and in order to avoid these limitations, it is recommended to use a more meaningful interpretation of the results of forecast calculations.

The article considers S.A. Karaganov’s concept of Siberization and the possibilities of using such theoretical tools as V. Christaller’s theory of central places and A. Lösch’s theory of economic landscape for its implementation. It is concluded that a version of the relativistic theory of central places for systems with a dispersed (distributed) main center may be useful for describing and planning urban settlement systems in Asian Russia, which are significantly less mature than those in the European part of the country. In the Far East, it is possible to form a system of central places with a hierarchy corresponding to <i>K</i> = 2. It has been established that settlement development in the post-industrial period should not be treated as a secondary factor in relation to production development, since the standort (location) of modern enterprises should ensure not only reduced costs for energy, raw materials and semi-finished products, as well as proximity to markets, but also advantages in the competition for highly qualified labor. Only a high-quality urban environment can provide these benefits. It is reasonable to expect different patterns of production distribution in the north and in the south of Siberia. In the north, according to Weber, the standort should ensure minimal costs, while in the south, the location according to Lösch will predominate. Such a standort ensures maximum profit. It is shown that even in the most developed regions of Siberia, the location of new high-tech production facilities “according to Weber” is still inevitable. This follows from the continuous nature of territorial development established by B.N. Zimin: each new industry develops it anew. Siberization is being hampered by a serious delay in the implementation of long-discussed railway infrastructure projects: the Barentskomur, the North-Siberian Railway, and the Northern Latitudinal Passage. Only the construction of these railways will significantly increase the cargo-generating base for the ports of the Northern Sea Route. Meanwhile, projects far less urgently needed for the country are being discussed, such as a bridge to Sakhalin and even a tunnel under the Bering Strait.

The study demonstrates that the flow of tourists to the Arctic zone of the Russian Federation has been growing in recent years. The potential positive role of tourism in the socio-economic development of the Arctic, with its particular importance for ensuring the territorial integrity and security of the country, has been confirmed. Accordingly, the article substantiates the relevance of studying the process of development of Arctic tourism and the problems associated with it, specifically, of analyzing existing trends and identifying prospects for the development of Arctic tourism based on expert assessments of operators of the tourism services market in the Arctic zone of the Russian Federation, obtained during a series of interviews. These expert assessments were compared with the position of federal authorities, as reflected in regulatory documents. Data from the Federal State Statistics Service and the Unified Federal Register of Tour Operators, analyzed using applied statistics methods, were also used. It is shown that Arctic tourism is considered in regulatory documents as a tool for strengthening the sustainability of the Arctic, and its identification as a special type of tourism is based both on the commonality of its objectives and the potential to replicate successful practices. The following was revealed: for tour operators, their activities are not simply a source of income but also a vital mission, stemming from the desire to show their small homeland to a wide range of people. It has been confirmed that tour operators primarily discuss what is needed to improve the sustainability of tourism itself. It has been established that there is a significant divergence in tourism development trends, its prospects and the factors determining this for different regions of the Arctic zone of the Russian Federation. The main trends in the Arctic tourism development have been identified, including a decrease in the share of foreign citizens and changes in the quality of infrastructure. A number of recommendations are made for federal authorities on the Arctic tourism development.

The article presents the results of the study of chemical pollution of sewage sludge, soil, and surface watercourses with heavy metals in the area of used sludge ponds. High total contents of Zn, Cu, Ni, Cr, Ni, Pb and the metalloid As were found in sewage sludge. The highest concentrations were found for Cu (3,2-84,2 MAC) and Zn (3,0-77,9 MAC). Sampling of soil adjacent to the sludge ponds revealed excess levels for a number of heavy metals, with the maximum concentrations detected at a distance of 3 m from the boundary of the sludge ponds. The excess for Zn and Cu amounted to 37,5 MAC and 25,4 MAC, respectively. At a distance of 25 m from the sludge ponds, the excess was found mainly for Cu (1,05-1,69 times), and at a distance of 100 m and 650 m it was revealed for Zn and Cu. The ingress of heavy metals into the soil of adjacent areas indicates that the sludge ponds were constructed without isolating protective structures. The physicochemical properties of sod-podzolic sandy-loam soil contribute significantly to soil pollution with heavy metals. In samples of surface water, as well as in soil, excess levels of Cu, Zn, Fe, Ni, and Pb were detected. Particularly high concentrations are characteristic of Cu and Zn, which is primarily due to their increased migration activity along the soil profile, compared to other heavy metals. Addressing the problem of chemical pollution of used sludge ponds with heavy metals primarily involves mandatory remediation measures, using modern technologies such as geotubation of sewage sludge. The results of these studies can be used to assess anthropogenic impacts on soil and to scientifically substantiate necessary environmental protection measures.

The article examines the application of the methodology for assessing the potential natural vulnerability of landscapes using Khabarovsk Krai as an example. Based on the performed calculations, seven categories of landscapes were identified according to the degree of integral vulnerability - from extremely high to very low, and the contribution and spatial distribution of individual vulnerability components (pyrogenic, soil-cryogenic, etc.) to the overall indicator were analyzed. The territorial distribution of the assessment indicators was presented in a series of maps. It was revealed that extremely vulnerable geosystems (mainly highlands and heavily dissected mid-mountain areas with goltsy, mountain tundra communities, etc.) and highly vulnerable geosystems (mid-mountain and low-mountain areas with coniferous forests and post-pyrogenic grass-shrub communities) are insignificantly distributed, occupying 3,4 and 7,9 % of the territory of the krai, respectively. Natural complexes with low and very low values of the indicator are most widespread (44 % of the krai’s area). These are primarily flat and foothill geosystems with a wide distribution of bog, meadow-bog types of vegetation. The resulting information and cartographic database has a level of detail corresponding to a map scale of 1:500 000 and can be used in the development of territorial planning schemes at the level of “subject of the Russian Federation - municipal district” during the procedure of ecological and economic zoning of the territory and the designation of the category of “highly vulnerable landscapes” with a regulated use regime when identifying lands of high conservation value.

The influence of atmospheric circulation on the ice regime of Lake Baikal from 1952 to 2025 was studied. The timings of freeze-up and ice break-up of the lake in the southern, middle, and northern parts of Baikal were analyzed. Synoptic situations preceding the late freeze-up were also analyzed. It was found that changes in the timing of freezing and breaking up of the lake ice led to a reduction of the period of ice cover. Since the mid-1970s, the dates of freeze-up on Baikal have become later and have shifted from the end of December and the beginning of January to the end of January. The ice break-up dates have shifted from mid- and late May to early May and late April. Over the past 70 years, the period of ice cover on Baikal has decreased by 19 days. The maximum ice cover duration values were observed from 1955 to 1975, the minimum ones have been recorded starting from the 1980s. The shortest period of ice cover occurred in 2025. Compared to the average long-term values, the period of ice cover was 29 days shorter in the southern part, 38 days shorter in the middle part, and 22 days shorter in the north of Lake Baikal. The influence of zonal atmospheric circulation on the lake’s ice regime was revealed. Late freeze-up is preceded by the latitudinal transport of warm air masses from the Atlantic, southwestern transport of air masses in the middle and lower troposphere from the regions of Central Asia, active North Atlantic cyclogenesis, and activation of the upper frontal zone. The weakening of the Siberian anticyclone has a significant impact on the ice regime of Lake Baikal.

The characteristic features of distribution and behavior of the Baikal omul were studied for the first time using static hydroacoustic recording from the ice cover of Lake Baikal in the Selenga shallows, as well as in the adjacent deep-water area near the villages of Buguldeika and Bolshie Koty. The analysis of acoustic data on changes in fish aggregation density made it possible to assess their distribution and migration patterns. At the “Selenga” station, fish schools were observed moving at the same depths throughout 24 hours, while at the “Buguldeika” and “Bolshie Koty” stations, individuals aggregated into small groups at depths of 100-200 and 250-350 m, depending on the time of day. The reconstructed fish size composition from acoustic data based on the target strength of individual fish made it possible to determine the characteristics of their migrations at different stations. At the “Selenga” station, a high proportion of fish with a standard length of up to 17 cm was detected, indicating the presence of juvenile fish from the spawning river. In contrast, at the “Buguldeika” and “Bolshie Koty” stations, predominantly individuals with a standard length (SL) of 20-38 cm were recorded, which indicates the migration of fish over two years old from the underwater slope zone of the Selenga shallows to the mesopelagic zone. The study results demonstrated the fundamental feasibility of monitoring the distribution, migration patterns, and formation of the size composition of fish using the hydroacoustic method in static mode during the winter period. This opens new perspectives for studying the seasonal fish behavior and helps to better understand their ecology and interrelations in the natural environment.

The soils of high-arctic and typical tundras of the Barents Sea islands (Mabel Island of the Franz Josef Land Archipelago, Severny Island of the Novaya Zemlya Archipelago, Kolguev Island) were studied. The article considers the features of formation and morphological structure of soils in the concept of tundra soil formation. The taxonomic position of soils was determined within the framework of substantive-genetic classification systems. A comparative analysis of zonal and landscape conditions of soil formation was carried out. It has been concluded that the harsh climatic conditions and fragmentary nature of the soil cover of high-arctic tundras determine the formation of thin profiles with weak morphological manifestation of soil horizons. It has been revealed that in typical tundras of the island landscapes, full-profile zonal tundra soils are formed under natural vegetation. Moreover, the specifics of soil formation at the landscape level are determined by the composition and structure of parent and underlying rocks. The influence of landscape conditions is most pronounced on mountain islands, where shallow rocky soils have formed. In high-arctic tundras, cryogenic psammozems and lithozems develop on various rock types, while typical tundras produce gley and peaty cryogenic soils. It has been shown that the high rockiness of soils and underlying rocks contributes to an increase in the depth of seasonal thawing. The occurrence of permafrost in the depth of underlying dense rocks limits the possibilities of its manual probing, making ground penetrating radar methods the main ones in studying the depth of soil thawing. Differences in the genesis and morphological structure of soils of high-arctic and typical tundras are due to the significant latitudinal extent and great diversity of landscapes in the island Arctic.

Based on meteorological station data for 1952-2020, long-term changes in the main climate indicators in the study area of the lower Yenisei basin were analyzed. Air temperature trends are characterized by a steady increase at a rate of 0,39-0,45 ° C/10 years; for most of the meteorological stations under investigation, an increase in atmospheric precipitation was noted for the period from 1966 to 2020 amounting to 2,4-32,6 mm/10 years. The influence of climate on the current conditions of formation and ongoing changes in the regimes of annual and winter low-water runoff of the lower Yenisei river basin was studied. It is shown that the noticeable climate warming in the lower Yenisei basin over the past decades has been accompanied not only by a rise in air temperature and a slight increase in precipitation, but also by a change in the annual and winter low-water runoff. Using hydro- and meteorological data, an analysis was conducted of changes in the average annual and average low-water runoff for the entire observation period (1939-2020) and for the period of modern air temperature increase (1976-2020). The analysis of changes in winter low-water runoff by years for different periods revealed that, since the 1940s, all the studied rivers showed a tendency toward an increase in this indicator from 0,13 to 1,25 mm/year. The annual runoff also increased on all rivers from 0,09 to 0,93 mm/year. This indicates a general trend of increasing river runoff in the study area of the lower Yenisei basin. According to the results obtained, the trend in the winter low-water runoff during the period of modern climate warming is more pronounced compared to the annual runoff. This demonstrates that permafrost thawing is becoming a more significant factor in the formation of the river runoff in the lower Yenisei basin.

The article considers the conditions of formation of carbonic mineral waters common within the Khentei-Daurian vault, located in the neighbouring territories of Russia and Mongolia. This area belongs to the Daurian hydromineral region. Currently, 28 manifestations of carbonic waters are known, but there is a high probability that their number will increase with detailed research of this hard-to-reach territory. All carbonic springs are associated with tectonic fault zones. They are characterized by low water temperatures and high CO₂ content. The main anion of the studied waters is bicarbonate, while calcium and magnesium predominate among the cations. Elevated concentrations of several balneologically valuable microelements are noted in the spring waters. One of the most valuable components is iron, which is present in all the studied springs. According to existing classifications, carbonic waters of the Khentei-Daurian vault belong to the Darasunsky, Kukinsky, and Lastochkinsky types. The analysis of the isotopic composition of carbon has shown that CO₂ is of magmatic origin. Some enrichment with the light carbon isotope is explained by the influence of organogenic carbonic acid from coal seams or from peat bog deposits. There are resorts in Mongolia operating on the basis of carbonic waters of the Khentei-Daurian vault. In Russia, the former “Yamarovka” resort is used for bottling mineral water for retail sale; other carbonic springs are visited by vacationers without any organization. In addition to the water’s healing properties, the carbonic springs of the Khentei-Daurian vault are natural monuments and require constant protection from pollution and depletion.

The resilience of forest ecosystems to natural and anthropogenic impacts was studied. The influence of climatic, biological, landscape, and anthropogenic factors on the productivity of forests in the Zeysky Nature Reserve was assessed. Climate trends and the sensitivity of the phytoproduction process to changes were analyzed, and a periodization of hydrothermal parameters was provided. The research methods included collecting tree cores to estimate annual increments and analyzing climate data using statistical methods. Based on the analysis of tree-ring chronologies, the relationship between climatic fluctuations and radial tree increment was retrospectively assessed. To improve the accuracy of the analysis, methods of cross-dating and standardization of tree-ring series were used. The resulting time series of tree increment were compared with the data on air temperature and precipitation provided by the nearest weather station. Correlation and regression analyses were used to assess the statistical significance of the identified relationships between climatic factors and tree increment. Specifically, the Pearson correlation coefficients were calculated between tree increment and average monthly temperature and precipitation values for different periods of the growing season. The results of the regression analysis made it possible to assess the contribution of each climatic factor to the overall variability of tree increment. It has been established that temperature conditions, especially in spring and summer, significantly affect tree increment, while precipitation plays a secondary role. At this stage of research, it was not possible to identify a clear influence of climatic factors on forest productivity in the long or short term. Despite the correlations identified, it is necessary to consider the influence of other factors, such as competition between trees, stand age, soil conditions, and the impact of pests and diseases, which may mask or enhance the influence of climatic factors.

The manifestation of the Little Ice Age in the south of the mainland of the Russian Far East is analyzed. The study is based on a synthesis of paleogeographic data, which, in the absence of historical records, are the most informative for reconstructing changes in the natural environment. The main natural archives were deposits of mountain lakes and bogs located in different landscape zones of the low- to mid-mountain areas of the Sikhote-Alin and East Manchurian Mountains (at absolute elevations from 300 to 1600 m). Based on changes in the composition of diatom flora, as well as components of forest and bog ecosystems, abrupt climatic changes that occurred from the 12^th to 13^th centuries, including the transition period from the Medieval Warm Period, were reconstructed. It has been established that the medieval cooling in the south of the Far East was humid, with increased precipitation, including winter precipitation, and frequent floods. In this context, short-term periods of decreased humidity and seasonal droughts were observed. Typically, drier conditions coincided with solar activity minima. The cooling had an impact on the development of mountain landscapes, resulting in a change in the ratio of forest-forming species, a shift in the boundaries of landscape zones, widespread development of sphagnum bogs, and the emergence of species of northern regions among peat-forming plants. At the end of the Little Ice Age, settlement and active development of the territory became the leading factor in landscape transformation.

The relevance of the study is determined by the low population size and density, as well as the shortage of labor resources in Siberia amid depopulation and migration outflow from the territories. Significant differences in the socio-economic status of Siberian subjects determine the population movement to more developed regions, exacerbating territorial disparities in the distribution of labor resources in the labor market. The novelty of the study lies in its comprehensive approach to studying the relationships between demographic processes, economic development of the territory and social changes in society. The features of territorial dynamics of the population in the labor market (in terms of size, growth, distribution of those employed in economic sectors, and unemployment rate) are analyzed, taking into account the influence of economic and demographic factors. Regional factors that determine the increase/decrease in the total population, the working-age population and those employed in the economy have been identified. Between 2011 and 2023, significant shifts occurred in the overall structure the population employed in the economy, with a reduction in the total number of this group within one percent. The greatest decrease in the number of employed people was typical for agriculture, education and healthcare. The largest increase in the number of employed people was recorded in trade, in such areas as the repair of vehicles and household goods, transport and communications, and in the extraction of minerals. The matrix of labor market indicators, the quality of life index, the ratio of median income to the cost of a set of goods and services, and the share of the population below the poverty line revealed a clear correlation between economic and socio-demographic indicators.

The article provides a review of publications on the problems of water management activities and riverbed processes under dynamic natural and anthropogenic impacts. Various approaches in this field (ecosystem, basin, and integral ones) are characterized. It is shown that the need to analyze the socio-ecological consequences of water management activities and riverbed processes is currently increasing. Particular importance is given to sociological methods in studying the issues of managing these processes. To illustrate the effectiveness of these methods, the authors present the results of an expert interview and a supporting qualitative in-depth interview with the local population, using the central regions of the Sakha Republic (Yakutia) as an example. The analysis of expert knowledge and public opinion made it possible to identify the main risks and factors of anthropogenic impact on the Lena River, which are most often encountered by specialists and ordinary residents of the region. The main socio-ecological consequences of water management activities and riverbed processes are identified. The strengths and weaknesses of the methods of riverbed process management are formulated. Expert and public opinion on the problems of water management and planning on the Lena River is summarized. It was found that when assessing social consequences, their primary manifestations (human and economic losses) are usually indicated. More complex social processes are mentioned only by some experts and do not have a consistent reproduction of opinions. In general, experts point out that coordination of methods for managing risks caused by riverbed processes should be improved in order to harmonize the activities of various agencies facing relevant problems. It is concluded that, given the weak formalization of the considered ideas and the conflicting interests of various social groups, the use of methods for studying the expert opinions of managers with a supporting public opinion survey proves to be effective.

The article considers the issues of methodological support for assessing the possibility of using archaeological sites in tourism activities. The research base of the identified topic in the global and Russian scientific fields is analyzed. The presented authors’ methodology evaluates each site according to five parameters, namely: transport accessibility, infrastructure provision, events, available excursion programs, as well as public activity. Based on the results of applying the methodology to five districts of the southwest of Rostov oblast (Azovsky, Aksaysky, Myasnikovsky, Rodionovo-Nesvetaysky and Ust-Donetsky), the archaeological sites most promising for inclusion in tourist-excursion routes were identified. The advantages of sites with high ratings in these districts are also described. Proposals for the further use of the assessed sites in tourism, including consideration of the differentiation of their ratings, are presented for discussion. Based on the conducted research, the authors suggested a tourist route with an archaeological focus through the territory of Rostov oblast, “The Solar Plexus of Eurasia”, which includes the sights of the region’s southwestern districts with the highest ratings. Such a route can become a growth point for inbound archaeological tourism in the region and, in the long term, serve as a basis for the formation of infrastructure-supported tourism development poles. For low-rated sites, measures have been proposed to increase their tourist attractiveness and potential use in tourist routes. Furthermore, the prospects for applying this methodology to other districts of Rostov oblast, as well as to other subjects of the Russian Federation, with the possibility of forming national archaeological routes, are outlined.

Precipitation is a key indicator for determining the climate of a region. However, erratic precipitation patterns are detrimental to urban infrastructure. The objective of this study is to forecast precipitation patterns using historical time series data. The study used precipitation data for a century (1922-2022) to project future precipitation trends for the semi-arid region of the Agra district of Uttar Pradesh, India. A seasonal autoregressive integrated moving average (SARIMA) model was employed for the same purpose. Through data decomposition and the augmented Dickey-Fuller test, the study confirms the model’s stationarity prerequisites, with the SARIMA (2, 1, 1) (0, 1, 1)12 configuration proving to be the most accurate for the study. The model accuracy was further validated through residual checks and performance assessment against established metrics, such as the Akaike information criterion, Bayesian information criterion and Hannan-Quinn information criterion. Forecasts were generated at 80 % and 95 % confidence intervals using both the “pm.auto_arima” function of the “pmdarima” package in the Python library and manual assessment for further adjustment and verification. According to the forecasts, 2022-2031 is a decade of reduced precipitation, with an average of 590 mm. This forecasted average is lower than the historical average of 643,96 mm and the median of 665,92 mm.

The article considers the problem of migration of herders from rural to urban areas of Mongolia in the wake of the country’s transition to a market economy in the 1990s. The consequences of these reforms were the loss of some livestock (the source of livelihood for rural residents), including due to natural disasters, and a lack of jobs. The article presents an analysis of the main indicators of the internal migration in Mongolia from 1990 to 2020 at the province and soum levels, and determines the changes in the population distribution and settlement system due to the internal migration. Over the past 30 years, the population of Mongolia has increased by 1203,2 thousand people, or 58,7 %. It was found that this population growth (averaging 2 % per year) differed greatly geographically. Thus, during this period, the population of Ulaanbaatar increased by 962,5 thousand people, or 179,4 % (an average of 6 % per year), which is directly related to the flow of internal migrants towards Ulaanbaatar. An analysis of the average annual population growth rate suggests that in two provinces and 21 soums, the population grew mechanically or by migration; the average annual growth rate above the national average was observed in 9 province centers and 19 soum centers. In the future, it is necessary to identify and analyze the factors influencing internal migration in order to reduce population concentration in Ulaanbaatar and other large cities of Mongolia and to stimulate return migration.