Russian State Hydrometeorological University

As high-speed rail operations increase and extreme weather events intensify, the stability of railway subgrades faces greater risks. Previous studies often focus on direct impacts but overlook complex interactions. Here, we use structural equation modeling to examine the relationships between climate, land use, geomorphology, geology, spatial factors, and operational characteristics influencing subgrade defects in China’s high-speed rail system. Data used in this study were obtained from official documents and open-source databases, including land types, subgrade defects, and weather patterns. Our results show that land types like sandy and bare lands contribute to subgrade defects. Both geomorphology and operational characteristics play key roles, with geomorphology affecting subgrade stability indirectly. Bare land influences settlement and uplift deformation, while frost damage and mud pumping are driven by freezing days and rainfall. Projections indicate that the risk of subgrade defects will increase in the future, underscoring the need for proactive resilience measures.

The work is aimed at testing mathematical models in the form of differential equations for short-term forecasting of water content of a small mountain river in Armenia. The hydrometeorological characteristics of the Arpa River, Jermuk post were used as initial data: water discharges, precipitation amount, air temperature, snow depth in the catchment area. Verification forecasts of water discharges from March to July for nine years were issued with a daily lead time. It was found that for the Arpa River, the first and second order models show satisfactory results in forecasting water discharges during the spring flood. The best results are shown by the second order model, which takes into account both surface and subsurface runoff. It was revealed that the model parameters can be optimized with a large error, in particular, the coefficient responsible for the intensity of snowmelt. An analysis of the obtained results was made, which were transferred to the Hydrometeorological Center of Armenia.

The work is devoted to the assessment of the winter minimum average monthly runoff of the Lake Sevan basin. Analysis of the temporal distribution of the studied hydrological characteristics was carried out. The study used data on daily water consumption at 12 hydrological posts, located within the basin of Lake Sevan. The purpose of the research is to calculate the norm of winter minimum average monthly discharges, coefficients of variability (Cv) and skewness (Cs), minimum discharges of different security, to analyze and evaluate the patterns of modern changes in winter minimum average monthly discharges of the rivers of the Lake Sevan basin in a series of long-term observations. Reliability curves have been constructed, and the values of the minimum monthly runoff with a different security have been estimated. It has been established that the basin of Lake Sevan is distinguished by the variety of risks of minimal water flow in the winter period. The obtained statistical materials will serve as a basis for scientific generalizations of the results achieved, and can also be used for practical purposes in hydraulic engineering design, assessment of natural hazards and the adoption of appropriate preventive measures and solutions.

Throughout the 20th century and the first decades of the current century, the Mute Swan, Cygnus olor, has been growing in numbers and expanding its range both northward and northeastward. The history of the introduction of this species into northwestern Russia and the main stages of its expansion, as well as the peculiarities of its spatial distribution in the region, are discussed. The Mute Swan started breeding in northwestern Russia in the mid-1980s. The species settled in two landscapes: on shallow eutrophic lakes and on sea moraine and selga islands. To date, the species range covers the eastern part of the Gulf of Finland, the western and southwestern parts of Leningrad oblast, all of Pskov oblast, and the westernmost parts of Novgorod and Tver oblasts. It is noteworthy noting that at the initial stages of expansion the first breeding pairs appeared throughout most of the above-mentioned territories at once. Subsequently, new nests were recorded mainly within the “occupied zone” delineated by the first newcomers. Over more than 30 years of expansion, the range of this species moved eastwards by no more than 88–94 km into different localities, while during the previous 20 years (1960–1980) the range of the Mute Swan in Scandinavia moved up to 998 km. Decreasing rates of range expansion amid the continued development of a warm phase of the climate suggest the presence of some kind of climatic barriers for the species in the region.

SWOT observations are shedding new lights on internal wave (IW) dynamics with coincident sea surface height and roughness modulations responding to the passage of IWs. Traveling IWs strongly impact inner layers of the upper ocean, with localized intense vertical motions shifting the boundary between warm and cold water by up to 100 meters. SWOT high resolution sea surface height measurements help clearly identify IWs with wavelengths from about 3 to 50 kilometers. These measurements, combined with radar intensity signals, open new means to quantify sea surface roughness hydrodynamical modulations. The strongest signatures are confirmed to occur under weak wind conditions and when IWs travel along the wind direction. Overall, SWOT combined observations quantify the upper ocean’s inner dynamics, and can help quantifying IWs effects, which is valuable for various applications.

The article examines the poetics “We read Blok until morning...” (1997) by B. Ryzhy as the embodiment of the poet’s existential worldview. The combination of intertextual and structural-semiotic approaches to the study of a literary text makes it possible to understand the event vector of the self-determination of B. Ryzhy’s lyrical “the self” and to determine the relationship between vital and mortal principles, the problematization of which forms the value-semantic center of the poet’s creative reflection. The analysis of the poem shows that this poetic text, revealing explicit and implicit layers of intertextuality, demonstrates the poet’s existential immersion in the existential processes of anthropological self-actualization on the verge of life and death. The ontological tension of the artistic world represented by the poet consists of the quotation interaction of the lyrical systems of A. Blok and G. Ivanov, who, presenting themselves as a single axiological center, form an eventful introduction to the world of death through the poetics of quotation. The mortal meanings of the poet B. Ryzhy’s self-determination, a rmed in the poetics of his poem and ontologically overcome by the memory of the value acceptance of being, are revealed through vital familiarization with the awakening earthly world order. The triad “morning, youth, fatigue” appears as the formula of being in which the lyrical subject of B. Ryzhy. It is concluded that the quotation tension between Blok’s and Ivanov’s existential worldview and the lyrical worldview proper reveals the ultimate existential tension of life and death, which is constantly and inevitably of interest to the poet B. Ryzhy.

The study examines the impact of agrometeorological conditions, particularly rainfall patterns, on rice yield over the past 30 years in the Anuradhapura Province of Sri Lanka. Anuradhapura is one of the primary rice-growing regions in the country. Long-term data on rice yield †and humidity indices were analysed. The island's climate, especially seasonal monsoon rainfall, significantly influences rice production. Changes in monsoon patterns, rainfall regimes, and air temperature directly affect rice yield and food security. Favourable weather conditions for rice cultivation and yield improvement have been identified.

Tidal dynamics along the shelf break and continental slope of the Kamchatka Peninsula, adjacent to the Pacific Ocean, are a significant but underexplored factor influencing the hydrological variability. This variability affects the distribution of early life stages of the Eastern Kamchatka population of Walleye pollock, a key species for Russian fisheries. Its spawning occurs mainly in the deep-sea canyons of Avacha and Kronotsky Bays. This study aims to describe the methodology developed to investigate the impact of tidally driven hydrophysical processes on pollock egg distribution, with a focus on its application in the deep-sea canyons of Avacha Bay. Two experiments were conducted in the "Central" and "Northern" canyons during the peak of pollock spawning in April 2024, coinciding with the spring tide when tidal effect on the environment is maximized. The experimental methodology was based on frequent hydrological profiling and layer-by-layer sampling of ichthyoplankton, carried out over a day. The study identified a 50-meter amplitudes of vertical oscillation of the thermocline, located at 320–420 meter between warm and cold intermediate layers, with a distinct diurnal rhythm in the "Central" canyon and semidiurnal one in the "Northern" canyon. These results highlight the critical role of tidal dynamics in shaping hydrophysical variability, which in turn potentially affects pollock eggs vertical redistribution and development in the deep-sea canyons of Avacha Bay.

Since 2013, stringent clean air initiatives have significantly reduced atmospheric pollutant emissions in China, improving air quality and altering the spatiotemporal patterns of pollution. Utilizing fine particulate matter (PM2.5) and its chemical composition data from 2000 to 2023, we observed a reduction in the disparity of PM2.5 concentrations between urban and nonurban areas. This reduction is linked to stricter emission controls in urban areas and the relocation of some emission sources to nonurban areas. However, the specific chemical constituents of PM2.5 and the driving factors behind these changes remain to be fully elucidated. By analyzing the proportions of PM2.5 components in major cities such as Beijing, Shanghai, and Guangzhou and their surrounding nonurban areas, we found that the narrowing gap in PM2.5 concentrations between urban and nonurban regions is associated with the convergence of the organic matter (OM) proportions in both areas. This convergence results from varying emission reduction strategies tailored to the distinct characteristics of urban and nonurban pollution sources in China. Coordinated governance between urban and nonurban areas should be considered, along with the implementation of integrated control and mitigation measures for multiple pollutants to further enhance air quality in China.

This study analyses the wide-band algorithm, Cloud-J v.8.0, from the point of view of the validity of the choice of wide spectral intervals to accelerate the calculations of photolysis rates in the lower and middle atmosphere, considering the features of solar radiation propagation, and to assess the influence of the processes of reflection and scattering on molecules, aerosols, and clouds. The results show that the calculations performed using Cloud-J v.8.0 are in agreement with the data obtained using the high-resolution LibRadtran model. The study also considers the factors influencing the propagation of the solar flux through the atmosphere in Cloud-J v.8.0, which occurs following theoretical concepts. It is shown that the presence of cloud layers can increase photolysis rates by up to 40% in the above-cloud layer and decrease them by up to 20% below the cloud layer. The presence of volcanic aerosol can increase the photolysis rates in the upper part of the layer and above it by up to 75% and decrease them by up to 75% in the underlying atmosphere. Rayleigh scattering can both enhance photolysis rates in the troposphere and reduce them at large zenith angles. Thus, Cloud-J offers a robust method for modelling atmospheric photodissociation processes with high computational efficiency.

Data on the new localities of Lemna minor, L. trisulca, and hybrid between L. minor and L. turionifera (L. × japonica) (Lemnaceae) in the north-west of the Murmansk Region (north of 68.5° N), i.e., in the Pasvik State Nature Reserve and neighboring territories in the drainage basin of the Paz River, are presented. Lemna minor and L. trisulca were previously known for the region by several reports. In the north-west of the Murmansk Region, 2 new localities of Lemna minor, 1 locality of L. × japonica, and 10 localities of L. trisulca were found. In total, representatives of Lemna occurred in 18 studied sites: L. minor in 2, L. × japonica in 2, and L. trisulca in 16 (L. minor and L. trisulca grew together in 2 sites). In the studied rivers and lakes, the pH range of water varied from 6.0 to 7.6, i.e., was mainly neutral (the average value was 6.9). TDS varied in the range from 17 to 251 ppm (on average, 53 ppm). The localities of L. minor in the unnamed lake near Zapolyarnyi town and in Kuetsjarvi Lake are probably the northernmost in the world, while locality of L. trisulca in the Paz River in Klistervatn Lake is the northernmost in European Russia. In the north of the Murmansk Region, L. minor and L. × japonica were associated only with anthropogenic eutrophicated water bodies with increased TDS in comparison to the background value. These taxa can be considered an indicator of high trophicity in this region. The localities of L. trisulca are mainly anthropogenic transformed water bodies. The maximum abundance of this species is also recorded in the areas of increased trophic level.

The gas composition of the Earth’s atmosphere largely determines numerous weather and climate processes and phenomena. The importance of studying the composition of the atmosphere stimulated in recent decades the creation of global and regional observation systems for water vapor, ozone and the substances depleting it, carbon dioxide and other greenhouse gases, and dozens of contaminant gases. A significant part in the global monitoring of the gas composition of the atmosphere is played by satellite observation systems which make it possible to obtain regular, global, and regional high-quality (in terms of accuracy and spatial resolution) data on its gas composition. The review is devoted to the analysis of present-day remote satellite passive methods for determining the gas composition of the atmosphere and the main results obtained to date. A modern classification of passive and active satellite methods, the physical and mathematical foundations of passive methods, the main characteristics of the used orbits of space carriers, and the types of geometry of satellite observations are given. The advantages and disadvantages of various satellite passive methods using measurements of atmospheric transparency characteristics (the eclipse method), Earth’s own radiation, as well as reflected and scattered solar radiation are analyzed for various satellite measurement geometries in a wide spectral region from UV to radio waves. A brief history of the creation of special modern satellite equipment is given, as well as their characteristics–information content, altitude measurement ranges, errors, and vertical resolution. Numerous results of global and regional monitoring of the atmospheric gas composition and examples of their use in various problems of atmospheric physics and climatology are presented.