Vol 63, No 1 (2023)

Small glaciers of the Polar Urals are at the limits of their existence. Their state and changes serve as an important natural indicator of modern climatic changes. In 2019 and 2021, we performed ground-based radar studies of one of these glaciers, the IGAN Glacier, to measure ice thickness and snow cover. We used Picor-Led (1600 MHz), and VIRL–7 (20 MHz) GPRs. According to these data, the glacier has an average thickness of 49 m, maximum 114 m. The glacier has a polythermal structure: a cold ice layer with an average thickness of 12 m (maximum 43 m), overlaps the temperate ice with an average thickness of 37 m (maximum 114 m in the upper part of the glacier). The volume of ice contained in the glacier (in its studied part) is 14.3 × 10⁶ m³, of which 10.89 × 10⁶ m³ is temperate ice and 3.44 × 10⁶ m³ is cold ice. For comparison: according to the radar data of 1968, the total ice thickness then reached 150 m in the central part, and the thickness of the upper layer of cold ice was 40–50 m. Radar snow gauge survey allowed to build schemes of seasonal snow thickness distribution over the glacier surface in 2019 and 2021, where there is a general spatial pattern of snow thickness growth from 2 m on the glacier terminus to 8 m or more to the rear wall of the corrie, which is due to the significant influence of avalanche feeding and wind transport. The glacier has lost about 3.2 × 10⁶ m³ of ice per last decade, if the rate of loss continues, it may disappear in 40–50 years. However, this process may have a non-linear nature, as it involves not only climatic factors, but also local terrain features, on the one hand contributing to a high accumulation of snow, on the other – the formation of a glacial lake during glacier retreat, which may increase ablation.

The aim of the work was to study the isotopic characteristics of precipitation to establish the dependence of δ¹⁸O values on temperature at the time of precipitation and to get closer to understanding the processes that form the isotopic signature of the Elbrus snow cover and glacial ice. The sampling of precipitation was organized at Azau station, located at the foot of Elbrus at an altitude of 2300 m for the period from May 01.2019 to September 27.2021. The sampling was carried out once a day at 9:00 Moscow time. The air temperature was recorded at the meteorological station in the Terskol village (Roshydromet station No. 4334250). To study the main features of long-range air transport and possible sources of moisture, 5-day back trajectories were reconstructed using the NOAA HYSPLIT_4 trajectory model. The results showed that precipitation in the Elbrus region in winter was associated with the prevailing transfer from the Atlantic, in summer – with the predominance of transfer from the regions of Central Europe, the Mediterranean and Black Seas. The Mediterranean Sea in all seasons was the area from which the air and moisture were transferred to Elbrus. The values of δ¹⁸О and δ²Н of precipitation varied from 0.52 to −28.22‰ and from 16.3 to −224.1‰, respectively, revealing regular seasonality with high values of δ¹⁸О and δ²Н in summer and low in winter. The deuterium excess varied over a wide range from 24.8 to −14.6‰. All obtained values of δ¹⁸О and δ²Н were approximated by the equation δ²Н = 8δ¹⁸О + 7.06 (R² = 0.98), which was close to the global meteoric water line. In general, for 2 years of observations, the relationship between the δ¹⁸О values of precipitation and the temperature of the surface air layer was expressed as 0.85‰/°С. Total mean absolute error in the reconstruction of air temperatures from the δ¹⁸О value of precipitation was 3.2°С due to objective reasons and also differences in meteorological conditions of two years of observations.

For two years (2021 and 2022) snow sampling carried out in the coastal zone of the Onega and Dvina Bays of the White Sea during the period of maximum snow accumulation (March). The snow was analyzed for the content of the main ions (Cl^–, \({\text{SO}}_{4}^{{2 - }}\), Na⁺, Ca²⁺, K⁺); biogenic elements (phosphorus, silicon, nitrogen), pH and mineralization were determined. The algological composition of the snow cover was also studied. The results showed that the snow was slightly acidic (average pH 5.4). Cl^– and Na⁺ were the main ions in the coastal zone; \({\text{SO}}_{4}^{{2 - }}\) and Ca²⁺ in the estuary zone. The high content of marine ions and mineralization were determined near the Paranikha Bay (Dvina Bay), where the release of sea water onto the ice is noted annually. Compared to previous studies, in which snow samples were taken in the costal zone, the content of marine ions in the territory under consideration is an order of magnitude higher. As a result of the influence of marine aerosols, the values of snow cover mineralization can reach 140–680 mg/L. The content of dissolved silicon in melt water is increased in the zone of influence of atmospheric emissions from urbanized territories (Arkhangelsk, Novodvinsk, Severodvinsk), as well as near the granite quarry on the coast of Onega Bay. During the study period, 14 taxa of microalgae (species and supraspecific taxa) belonging to the division Bacillariophyta were found in snow samples. The maximum value of the total number of microalgae (1.293 thousand cells/L.) in the snow cover was determined in 2022.

The huge Anmangynda aufeis is located in the valley of the river of the same name in the Magadan region in North-East of Russia. This is the only in the world aufeis site with a 30-years period of ground-based observations (1962–1991). The materials of these observations were supplemented with data obtained from the analysis of Landsat and Sentinel satellite images for the period 2000–2021, as well as the results of field investigations carried out in 2020–2021. The long-term variability of the maximum area, volume and average thickness of ice, the dynamics of formation and destruction of the aufeis ice in the cold and warm periods of the year were analyzed. It was found that the maximum values of the area and volume of ice on the dates before the start of ablation decreased by 25 and 33%, respectively. In 2000–2021, the average values of the aufeis characteristics are estimated as 4.7 km² and 7.1 million m³, while in 1962–1991 – 5.5 km² and 8.5 million m³. The analysis of the intra-annual dynamics revealed that the Anmangynda aufeis being earlier the perennial formation has transformed to the seasonal one. Further researches of the Anmangynda aufeis will make possible to assess the influence of various factors, including climatic ones, on the processes of an aufeis formation and to forecast their changes in the future for the cryolitic zone of the North-East of our country.

The investigation is concerned with the Early Holocene syngenetic massive wedge ice exposed in the outcrop of a polygonal peatland in the upper part of the third marine terrace near Lorino settlement on the eastern coast of Chukotka. Based on the obtained radiocarbon dates of peat, it was found that the formation of a peatland in the area began about 14–13 cal ka BP, at the end of the Younger Dryas, while the termination of the active stage of peat accumulation was dated to about 10–9 cal ka BP. The beginning of peat accumulation at the end of the Younger Dryas, earlier the officially accepted limit of the lower boundary of the Holocene (11.7 cal ka BP), and the termination of its formation by the middle of the Greenlandian Holocene period is not a rare phenomenon in Russian permafrost zone, although it is traditionally assumed that the most active formation of peatlands has been going on during the thermal maximum in the middle of the Holocene. The age inversions noted in the peat vertical profiles are the most likely indicative of the processes of re-deposition of ancient organic material due to erosion by water of the third marine terrace sediments and the separation of the allochthonous peat. During the period from 2015 to 2021, six fragments of peatland exposures with the ice wedges were studied. Analysis of the obtained data on the content of stable oxygen isotopes in the ice show that δ¹⁸О values vary within the range from –15.5 to –18‰. These values are in good agreement with the data for Early Holocene ice wedges earlier obtained in other areas of the eastern coast of Chukotka (Anadyr town, Uelen settlement), where authors report the δ¹⁸O values from –16 to –19.4‰. This suggests that the ice wedge growth as well as the peat accumulation were the most active in Early Holocene. The highest δ¹⁸О values (from –13.1 to –16.8‰) were obtained for the modern ice veinlets. The ratio δ²H–δ¹⁸O in the ice wedges, in general, is indicative of a good preservation of isotope signature of winter precipitation. It has been found that approximate mean January air temperature in the Early Greenlandian period varied from –23 to –27°С, which is, on average, 3°С below than the present-day ones.

The results of studies of the chemical composition and the basic regularities of migration of macro- and microelements within the hydro-cryogenic system “snow on ice–ice–water under ice” obtained in the winter of 2016/17 in the waters of Lake Baikal are presented. Such investigation over the Lake area was carried out for the first time. It has been found that due to climatic conditions, dates of freeze-up (formation of the ice on the Lake) differ by 7–10 days from North to South, and the depth of snow on ice and its density change over the Lake area by 2 times, however there are some parts without snow. It was found that the changes in the pH indexes were identical across the whole Lake area – minimum pH values are present in the snow (from 5.59 to 7.39), average values – in the ice (6.01–7.50), and maximum values are noted in the water under ice (7.42–8.50). For the most part, increased quantities of suspended matter and an increase in the pH of snow were recorded near settlements, which is obviously a result of the anthropogenic influence. It was determined that the concentration of ions in the ice in relation to their content in the initial solutions decreases within the series: \({\text{NO}}_{2}^{ - }\) > Cl^– > \({\text{SO}}_{4}^{{2 - }}\) > \({\text{HCO}}_{3}^{ - }\). Among the cations, K⁺, Na⁺ ions are involved into the ice intensively, while the Ca²⁺ and Mg²⁺ – weakly. The ice phase is enriched with ammonium ions outside the settlements. Near settlements and in shallow water, quantity of salts in the ice may be close to or equal to their concentration in the water under ice. The coefficient of migration in the water (Kx) divide the chemical elements into two groups – the mobile ones and slow-moving elements. The first group includes Ca, Cu, Sr, Mg, Co, Zn, and Cd (Kx >1), the second one contains Ba, Mn, Si, Fe, Al, Ti, Ni, Cr, P, and K.

This article presents a numerical solution of the one-dimensional Stefan problem with two phase transitions, which is implemented on a non-uniform grid. The system of equations is written in a general form, i.e. it includes not only conductive, but also convective and dissipative terms. The problem is solved numerically by the front-fixing method on a non-uniform grid using an implicit finite-difference scheme, which is implemented by the sweep method. This algorithm can also be used to create more complex mathematical models of heat and mass transfer, as well as to describe glacial and subglacial processes. The mathematical apparatus proposed in the article was used to solve a specific problem of water freezing in a glacial crevasse. The presence and progression of crevasses, in turn, is a demonstrative factor indicating the dynamic activity of the glacier. Crevasses formed in one way or another can not only expand, but also decrease in size until they completely disappear. One of the reasons for their closure is the freezing of near-surface meltwater in the crevasse. Such a process was observed on glaciers near Mirny and Novolazarevskaya stations (East Antarctica). This process is modeled as an example of solving the Stefan problem. It is believed that all media are homogeneous and isotropic. The temperature of the water in the crevasse corresponds to the melting temperature of the ice. Modeling has shown that for the coastal part of the cold Antarctic glacier with an average temperature of –10°C and below, crevasses 5–10 cm of width freeze in less than a week. Wider ones freeze a little longer. 30 cm wide crevasses close in about two to three weeks, depending on the temperature of the glacier.