Powerful HF radio waves interacting with the ionosphere accelerate or heat electrons, pushing the ionospheric plasma out of equilibrium and leading to the creation of various non-linear phenomena. One of the most prominent phenomena discovered from HF heating experiments is the generation of small-scale artificial field-aligned irregularities (AFAI). AFAI induce bi-static scattering of HF and VHF signals, providing their propagation in the frequency range and over distances unattainable in the natural ionosphere. This makes it possible to create HF-driven radio communication channels. We present results from an EISCAT/Heating (Tromsø, Norway) experiment on 18 February 2013, concerning the features and behaviors of AFAI in the high latitude ionospheric F-region induced by high power HF radio waves with O- and X-mode polarization using the bi-static scatter method. Joint use of various remote diagnostics tools, including the multichannel HF Doppler equipment, oblique sounding and the CUTLUSS backscatter radar provides a more comprehensive and complete AFAI study, including the size of the artificially disturbed region occupied with AFAI, the frequency band of bi-static scatter signals (BSS), the fine structure of BSS, the intensity, growth and decay times of AFAI. It has been found that O- and X-mode AFAI have different characteristics and generation mechanisms.

Snow plays an essential role in mass balance of different water objects on the Arctic archipelagos, such as rivers, glaciers and lakes. Snow cover sublimation has a significant effect on the amount of water stored in the snow. The Arctic and Antarctic research institute (AARI) has been performing sublimation observations on the Svalbard archipelago as a part of mass-balance research since 2021. The aim of the paper is to summarize and process observation results. Estimates of daily sublimation were obtained based on direct observations using GGI-500-6 weighing evaporimeters with an evaporating surface area of 500 cm² and monolithic snow 6 cm thick. It was found that during the spring period the average daily sublimation rate from snow is 0.60 mm w. e., during the day it is 0.43 mm, at night it is 0.17 mm, which is 40 % of the daytime value. There is a strong correlation between daytime sublimation and total daily sublimation, with the correlation coefficient r = 0.924. Between night-time and daytime sublimation rates, the correlation decreases to r = 0.742. The greatest influence on the sublimation process comes from wind speed (r = 0.822), moisture deficit (r = 0.670), and air temperature (r = 0.724). Based on the observations carried out from April to May of 2021–2024, a semi-empirical calculation method and a multiple regression model have been developed. These methods allow one to fill gaps in direct observations or to estimate sublimation when meteorological data are available. The methods were compared with the calculation methodology proposed by P.P. Kuzmin. A significant correlation was established between the results calculated using these methods (r = 0.776). The average amount of sublimated moisture as determined by these methods near the Barentsburg weather station in pre-spring and spring periods is 35.6 mm, ranging from 30.9 (according to Kuzmin) to 40.2 mm (semi-empirical method). The seasonal sublimation value according to the multiple regression model is close to the average — 35.7 mm. The daily sublimation intensity values, calculated from reconstructed series of 119 days and determined using Kuzmin’s methodology and the multiple regression model, are respectively equal to 0.63 and 0.66 mm/day. The results obtained can be used to assess the contribution of sublimation to the water balance of land surface waters in the Arctic archipelagos and the continental part of the Arctic.

During the Holocene, the level of Lake Ladoga was constantly changing. As a result, the coastal area of the water basin is characterized by the presence of accumulative landforms creating coastal morphosystems. The study of these paleomarkers allows us to detail the history of the lake’s development. This paper presents the results of a study of the Lake Ladoga Taipalovskii Bay coastal area. To achieve the aim geomorphological profiling of the Taipalovskii Bay coastal morphosystem was executed. It was supported with sediment sampling from sand landforms (beach ridges, barrier ridges, strandplains) and peatbogs for age determination using OSL and radiocarbon dating techniques. In summary, three peat cores and three coastal landforms were sampled during the fieldwork. It resulted in three OSL-datings and nine radiocarbon datings, which are presented in this paper. In addition, the materials of previous studies carried out on the sediment sections of the Vyun River first terrace were correlated with the data obtained. As a result, two phases of the relative lake-level rising were identified — Boreal-Atlantic and Subboreal-Subatlantic. The first one includes two stages corresponding with the Ancylus and Littorina transgressions of the Baltic Sea. During the Boreal (Ancylus) stage the relative lake-level reached its maximum around 8100 years BP. Its shoreline is marked at the altitude of 17–18 m above sea-level (a. s. l.). The Atlantic (Littorina) maximum shoreline, with an age around 6500 BP, is assumed to be at 14–15 m a. s. l. The end of the Atlantic-onset of the Subboreal climatic phase is characterized by lake-level decline. The second phase of lake-level rising started 3600–3700 years BP. This stage is correlated with the Ladoga transgression. The maximum rising of the transgression is defined at the altitude of 14 m with an age around 2600 years BP. After the maximum stage a second one is reported as well, which is determined at 2500 years BP. A shoreline at 11,5 m a. s. l. marks this event. As a result, it was established that the coastal morphosystem of Taipalovskii Bay was formed throughout the Holocene under the influence of the level fluctuation phases listed.

The current AARI complex of ice tanks was commissioned in 1990. Its modernization was carried out in 2022–2023 within the framework of a grant allocated by the Ministry of Science and Higher Education of the Russian Federation. In the course of the modernization, the refrigeration units of the large and small ice basins were renewed, a thermally insulated complex of rooms with a core storage facility was built, new measuring equipment was purchased, and the machine park of the model workshop was updated. The article discusses the results of the modernization and the capabilities of the complex of ice basins. 30 m long, 5 m wide and 1.8 m deep, the large tank allows ship models and offshore structures to be tested in various ice conditions. The ice basin has a deep-water part with a depth of 6 m, which is used to model the surfacing of underwater objects from under the ice. The small ice tank, 5 m in length, 5 m in width, and 2.5 m in depth is used to perform a wide range of studies on naturally frozen ice in the field of mechanics of deformation and fracture of sea ice. The small tank can also be used as a low-temperature laboratory to study the properties of various coatings and materials. The paper presents the most interesting and significant experimental studies carried out at the AARI complex of ice basins over the past 10 years. The studies include: self-propelled testing of ship models equipped with new remotely controlled rudder propellers including the testing of the new scientific expedition vessel «Ivan Frolov», currently being built for the AARI; physical modeling of the behavior of the ice-resistant self-propelled platform (IRSPP) “North Pole” under conditions of intense ice compression; physical modeling of the interaction of ice with hydraulic structures: bridge pears and shore reinforcement structures. The modernization of equipment and measuring devices contributes to a significant increase in the range of studies that can be performed using the AARI complex of ice tanks and enhances the quality of studies.

Ice compressions are among navigation hazards that impede navigation in freezing waters and sometimes result in loss of ships. Recent advances in the investigation of this ice feature enable its prediction and make it possible to recommend safe navigation routes for ships, bypassing hazardous zones. The effect of ice compression on hull structures is less understood. First of all, this is because ice compression actions are difficult to determine accurately and are currently estimated by means of special visual scales (marks) drawn on the hull. This paper proposes using the parameter of effective pressure for ice compressions. Effective pressure is always present in the case of ice compression phenomena, so it could be used as an assessment criterion for the added resistance of the ship. A similar approach has been successfully applied to determine the global ice load on engineering structures. This paper suggests a method for determining the effective pressure of ice compression based on ship propulsion performance data (engine power, movement speed and propeller RPM), as well as on the measured speed of ice channel closing behind the ship. These measurements must be taken in similar ice conditions with and without ice compressions. The speed of ice channel closing behind the ship could be used to quantify ice compression intensity. Added resistance of ships is calculated using the special diagrams of ice propulsion performance made which are made for specific ships based on the results of standard model tests in hydrodynamic tanks. The paper discusses the prospects and possible limitations of this method. Effective ice compression data would be very interesting for the prediction of operational conditions of Arctic transportation systems and, possibly, for the investigation of ice sheet dynamics.

The fossil mammoth tusk is a unique biogenic material, which is widely used for the production of souvenirs and luxury goods. The burial of mammoth fauna animal’s remains in permafrost ensured high preservation. Due to the complete ban on hunting African and Asian elephants introduced in 1990 by UNESCO, the demand for fossil ivory has increased. Today, up to 80 % of mammoth bone deposits is harvested in the Republic of Sakha (Yakutia), Russia. The paper describes some traditional techniques of mammoth tusk mining and proves the efficiency of the GPR (ground penetrating radar) for prospecting underwater accumulations of fossil mammoth bone. The aim of the survey was increasing the efficiency of the GPR sounding technique for the detection of mammoth bone under water. The comprehensive GPR area survey was used to identify areas promising to contain underwater accumulations of fossil mammoth bone. Because the release of bone material from productive layers is caused by river erosion and thermal erosion processes a meandering section of the Kolyma River was selected for the research. Thermal erosion plays a more prominent role in the release of bone material in the headwaters of small watercourses, in deltas, and in the bottoms of incipient gullies. Fossil mammoth bones are usually found on riverbanks (low floodplain, channel spits) — in areas where the river erodes the slopes of remnants composed of edomorphic complex formations or in close proximity to them. The GPR application makes it possible to study the bottom relief in detail and thus can identify areas promising in terms of the formation of secondary accumulations of mammoth bones. The key features of bone remain accumulations have been identified: natural depressions or obstacles that mammoth bone can get caught on when sinking to the bottom of the water body; accumulation of the heaviest fragments in the deepest depressions at the bottom of the water body; accumulation of smaller fragments on sedimentary shoals. An algorithm for the GPR surveying of water bodies promising in terms of mammoth bone detection has been developed.

The development of research-based approaches to the greening of cities built in the cryolithic zone was caused by the urbanization of USSR regions located in the Arctic and Subarctic climate. Over the past decades, the relevance of these approaches has been increasing due to the need for measures aimed at ensuring new standards of landscaping and environmental well-being of cities in the Russian Arctic. The main aim of this article is an integrated analysis of archival documents and scientific publications reflecting the evolution of research approaches and knowledge pertaining to the problems of greening cities built in the cryolithic zone of Western and Central Siberia in the period from the 1930s to the first quarter of the 21st century. The article describes the first attempts at greening the Arctic cities of Siberia made in the 1930s — 1950s and discusses approaches to zoning the green infrastructure of Arctic cities that have been developed in Russian science. The problems of studying the interaction of permafrost and vegetation in urban areas are analyzed. Based on examples of Siberian cities the paper examines problems of developing green infrastructure during the period of active urbanization of the Russian Arctic in the 1970s — 1980s. A brief overview is given of new approaches to urban greening in the Arctic cities in the first quarter of the 21st century. It is concluded that in recent decades, in most of the cities studied, there has been a trend towards a rise in vegetation characteristics such as NDVI and tree height compared with areas that have been left untouched. Researchers attribute this trend to factors such as regular planting of new trees and shrubs, targeted maintenance of green spaces, as well as the presence of urban heat islands and other favorable microclimatic conditions. It is concluded that such common factors as climate warming, an active introduction of alien plants into the urbanized environment and using new technologies for the improvement of northern cities contribute to the growth of opportunities for the development of the cities’ green infrastructure. At the same time, cryogenic processes and the way green infrastructure is developed in an urbanized environment are largely interdependent.