The paper presents the key results of investigating Barents Sea ice age composition during the winter season, from the beginning of ice formation in October to its termination in May. To analyze the seasonal and interannual changes in the amount of ice of different age categories, we used ice charts for the Barents Sea for the period 1997–2021, produced by the Arctic and Antarctic Research Institute. The age composition of the ice cover in the Barents Sea is represented by seven standard ice categories (thickness ranges). The areas of ice of different age categories were calculated for a ten-day time interval (in percentage of the total ice area). The results are provided for three parts of the Barents Sea: western, northeastern and southeastern.
The interannual changes in the amount of ice in relative fractions of ice of different age categories in the ice cover of the Barents Sea do not show significant trends for the period 1997–2021. Thus, with the observed reduction in the Barents Sea total ice area, the amount of ice of different age categories ranges within the limits of its own natural variability. Therefore, it is impossible to draw a definite conclusion about a decrease in ice cover thickness in the Barents Sea based only on data on the ice age composition over a 24-year period of observations analyzed in this study. On comparing the estimates obtained in this study of the age structure of the ice cover in the Barents Sea with those of the previous studies on this subject, we can argue that its average thickness at the beginning of the 21st century decreased, compared to the period 1971–1976. Taking into account the statistical insignificance of the trends in interannual variations in the amount of ice of different age gradations, one can maintain that quantitative changes in the age structure of the Barents Sea ice cover began earlier than 1997.

The ongoing decrease in the ice coveren is one of the main consequences of global climate change. The Barents Sea, as part of the North European basin, is an area that is one of the first to react to these changes. According to the AARI database, before the start of the current century the ice extent in the winter season varied from 600·10³ km² to 900·10³ km² in different years, while over the past 20 years the lower border has dropped to 350·10³ km². At the same time, the ice extent in the summer season has decreased more than 3 times. The aim of the article is to study the statistical structure of the longterm variability of the ice extent on the basis of the latest data, in order to identify the patterns of change characteristic of individual areas of the Barents Sea over the past decades. The main research methods include basic statistics, linear trend, stationary assessment, autocorrelation and the correlation coefficient. The work contains numerical estimates of the trend component for all the parts of the water area. The maximum contribution of the linear trend is due to the northeastern region and comprises 63 %. The maximum seasonal fluctuations are characteristic of the southeastern region, with almost complete freezing in winter (up to 99 %, as in the northeast) and complete clearing in summer and the absence of old ice. The same area has the least connection with the other parts (R less than 0.25) and the variability of its characteristics depends to a greater extent not only on the circulation of cold Arctic waters and the entry of warm Atlantic water, but also on river runoff. The north-eastern region is characterized by the capacity for retaining the “memory” of the previous state for more than 5 years, which indicates the highest inertia of the factors making for the variability of the ice extent. The speed of reducing the ice coveren because of melting is estimated at 1.76·10³ km²/month, while the rate of increase in the ice extent as a result of ice growth is estimated at 1.26·10³ km²/month. Accordingly, the ice melts faster than it has time to grow, which leads to a decrease in the ice extent.

The paper presents experimental results concerning disturbances of electron density in the high latitude ionosphere F-region, induced by powerfulHF radio waves (pump waves) with extraordinary (X-mode) polarization. The experiments were carried out at the EISCAT/Heating facility at Tromsø, Norway. The EISCAT UHF incoherent scatter radar (ISR), running at 930 MHz, co-located with a heating facility, was used to detect the disturbances of electron density. In the course of the experiments, the X-mode HF pump waves radiated into the F-region towards the magnetic zenith at different pump frequencies and ratios of the pump frequency to the critical frequency of the F2 layer.The effective radiated power was ERP = 360–820 MW. An increase in electron densities was found in a wide altitude range, giving rise to field-aligned ducts with enhanced electron density. The features and behavior of the ducts were investigated. It was revealed that the ducts are formed under quiet background geophysical conditions in a wide altitude range up to the upper altitude limit of EISCAT ISR measurements, when the pump frequencies were both below and above the critical frequency of the F2 layer (f_H ≤ f_oF2 or f_H > f_oF2). A plausible formation mechanism of the ducts is discussed.

The warming of the Arctic climate is confirmed by changes in the main hydrometeorological values of the atmosphere and ocean over a long period of time, and it is most pronounced in the recent decades. Based on monthly average data from the reanalysis of NASA MERRA-2 satellite measurements, we studied climate changes in air temperature, precipitation, and wind speed in the region of the western part of the Russian Arctic (60°–75° N, 30°–85° E) over 1980–2021. The transition between 2000 and 2001 was chosen as the time boundary between the periods, based on the application of the model of stepwise transitions from one quasi-stationary regime to another. Using this method, 2001 was found to be the smallest step year in the western Russian Arctic region. Significant changes in the parameters studied between the periods 1980–2000 and 2001–2021 are shown. Moreover, the strongest increase in temperature was observed for the months of November and April, which indicates a shift in the boundaries of the seasons — a later start and an early end of winter. It was found that in the period 2001–2021 the temperature increased most rapidly in the water areas of the Barents and Kara seas, and this growth occurred with acceleration. Negative temperature changes were found in the winter season in the areas where large rivers flow into the Barents and Kara Seas. It is hypothesized that this is due to the detected increase in the amount of precipitation in the catchment area of these rivers in 2001–2021 compared to 1980–2000. It is shown that the detected increase in the amount of precipitation is associated with a significant change in the atmospheric circulation in the region under study. In the summer season and September the western wind intensified in the region under study. During the winter season 2001–2021 in the Barents and Kara Seas the south wind increased compared to 1980–2000. Thus, significant changes in the climate of the western part of the Russian Arctic occurred during the time period considered. Westerly transport from the North Atlantic has intensified, precipitation has increased, and there has been an accelerated rise in temperature. All this contributed to the “atlantification” of the climate of the western part of the Russian Arctic.

The systems of internal drainage of glaciers have been studied mainly by indirect methods. In order to reveal the structure of the internal drainage network inside Aldegondabreen, moulins and glacial caves were investigated by speleological methods in 2001–2021, which was accompanied by a semi-instrumental topographic survey in the cavities. This allowed us to see the change in the glacial cavities over time. There are three types of moulins in Aldegondadreen: active, dead and healed ones. We visited active and dead moulins. The depth of the entrance pits in the moulins varies from 52 to 65 m (moulin group No 1), from 70 to 75 (moulin group No 2) and from 45 to 60 m (moulin group No 3). The depth of moulins is equal to the thickness of the cold ice layer. Using the structure of the moulins, we show that the water from moulin group No 1 flows to the right marginal part of the glacier tongue. The water from moulin groups No 2 and No 3 flows to the left margin part of the glacier tongue, which is confirmed by the mapping of healed moulins locations. We find that the number of active and dead moulins has been decreasing since 2001, while the number of healed moulins has increased. We attribute this to a decrease in the thickness of the temperate ice layer at the base of the glacier due to climate change. Many moulins have narrow meanders at the lower part of the entrance pits, which usually finish by siphons. None of the moulins reaches the glacier bed, their lower parts are usually located in clean transparent ice. The lifetime of the moulins usually does not exceed 6 years. Our study of the caves on the glacier tongue revealed that they can be englacial or subglacial, and they originate along sub-horizontal thrusts located in the ice. We assume that the moulins reach the slip planes along thrusts close to the glacier bed. The water from the moulins flows along these slip planes as a film in early summer and turns into channels in mid- or late summer. The presence of thrusts in the ice depths can explain the development of internal drainage systems in glaciers (regardless of their size), outbursts of glacial lakes, surges and the formation of eskers. Clastic material for eskers formation can penetrate into a cave channel from the contact areas of the thrusts with uplifts on the bed. The results obtained can help in the interpretation of the available geophysical data for this glacier.

Pollution of the hydrosphere, the atmosphere and the upper lithosphere by synthetic polymers has now become a global human problem. In this connection, a study of newly fallen solid precipitation was carried out from December 2020 to April 2021 in the north-west of the Kola Peninsula to identify polymeric particles that could be absorbed from the atmosphere by snow crystals. Snow sampling was carried out along highways at a distance from roads in calm weather. In the laboratory, melt snow water was filtered through nuclear filters, which were scanned under a binocular MBS-10 microscope to take account of insoluble polymer fibers. Simultaneously, filters stained with a Nile Red solution were analyzed under a Carl Zeiss AxioImager D1epifluorescent microscope for microplastic investigations. Synthetic polymer particles were identified among the aerosol material. The polymeric particle composition was strongly dominated by irregularly shaped polymer micro-fragments. Polymer macrofibres and polymer microfibers were also constantly present. By the research carried out the first assessment of polymeric particles flows to the earth surface with solid precipitation in the north-west of the Kola Peninsula was done.