Variations of the maximal depth of snow cover and snow density on the continental part of the Russian Arctic in different periods are considered. The distributions of the maximal snow depth and density are mapped. The values of snow density were taken for the moment when the snow cover thickness is maximal.

Дана оценка интенсивности замораживания капель воды при зимнем дождевании. Суточная производительность дождевальной установки DDN-70 составляет 670 и 2190 тонн льда из морской воды с минерализацией 35 г / л при температурах воздуха -10 и -40 °С. После таяния 50 % объема пористого льда, намороженного из воды с минерализацией 5 и 35 г / л, минерализация оставшейся части льда составит 0,003 и 0,8 г/л, соответственно.

The purpose of this research is to estimate the effect of snow cover on the store of cold of the glacier surface layer. The store of cold is a complex parameter that shows the degree of cooling of the surface layer of the glacier at the end of the cold period. This value is determined with regard for the dynamics of air temperature and snow cover, changes in the density and structure of snow, and the moisture content (water store) in the snow and firn layer by the beginning of the cold period. Analysis of data from measurements of the thermal regime of the upper 11‑meter layer of the East Grenfjord Glacier demonstrated that effect of the snow cover depth (thickness) on the store of cold is ambiguous: when the depth increases, the store of cold can both increase and decrease. For example, in the colder winter of 2013, the store of cold in the upper 11‑meter layer of the glacier was smaller than the similar value in the warmer and snowier winter of 2014. It was found that this was caused by influence of thaws and rains in the winter of 2014. They could produce changes in the structure of the snow cover: an increase in its density and hardness after freezing of ice grains, as well as increase thermal conductivity that could result in more significant cooling of the surface layer of the glacier this winter. Numerical experiments made possible to establish the dependence of the store of cold in the upper layer of the glacier on meteorological conditions and the snow depth. Calculations have shown that with the depth of 50 cm, a rise of winter air temperature by 1 °C reduces the store of cold, on average, by 8.5 MJ/m2, whereas with a snow thickness of 200 cm, the decrease is 6 MJ/m2. Increasing the snow thickness from 50 to 100 cm reduces the store of cold by 11 MJ/m2 at −6 °C, and by 15 MJ/m2 at −10 °C. And growth of snow thickness from 150 to 200 cm decreases the store of cold by 4 MJ/m2 at the temperature of −6 °C, and by 3 MJ/m2 at −10 °C. According to calculations for the compact snow with a thickness of 150 cm at −10 °C, the store of cold increases by 12% as compared with the average snow hardness. A more significant difference in the value of the store of cold happens when the stratigraphy of the snow cover is not taken into account. Note also, that when modeling the temperature regime and estimating the store of cold in the ice at the end of the cold period, one should take into account the moisture content of the upper 1-m ice layer at the end of the ablation period.

Climate changes have influence on the thermal stability of permafrost soils. The assessment of its changes should be made taking account of the parameters of the snow cover and its thermophysical characteristics. A method for determining the thermal resistance of snow cover and the effective coefficient of thermal conductivity of snow based on ground temperature is proposed for areas of the Arctic zone of the Russian Federation with negative ground temperatures. From data on ground temperature measurements at depths of 20 and 40 cm obtained from hydrometeorological stations, it is possible to estimate the heat flow from the ground into the snow cover and, at a known air temperature and snow depth, to calculate the thermal resistance of the snow and the effective coefficient of thermal conductivity. In this case, the obtained value of the thermal conductivity coefficient of snow will include all the features of the snow cover development by the time of measurement. To develop a method for determining the thermal resistance of snow cover and the effective coefficient of thermal conductivity of snow, numerical experiments were performed using a mathematical model, which allowed establishing the conditions for the applicability of the method. The paper presents results of calculations of the thermal resistance and thermal conductivity of snow cover made by the proposed method for winters of 2006/07 and 2009/10 in Yakutia for the snow cover of different thickness composed mainly by semi-skeletal and skeletal crystals of deep frost, reaching a diameter of 3–5 mm. The use of this method for the conditions of the Yakutsk with a known type of snow formation confirmed its effectiveness.

Изменения климата приводят к изменению температуры воздуха, продолжительности оттепелей и характеристик снежного покрова, которые оказывают определенное влияние на тепловой режим вечной мерзлоты. С 2001 по 2018 год повышение летней температуры воздуха на метеостанции Баренцбург составляло около 0,05 °C/год, тогда как зимней 0,21 °C/год. Продолжительность оттепелей увеличилась с 12 до 22 дней, а количество жидких осадков увеличилось в холодный период с 60 до 120 мм. Дана оценка влияния динамики температуры воздуха, продолжительности оттепели, структуры снега, толщины мха и снежного покрова на промерзание грунта.

The results of mass balance observations of the ice dome and measurements of the active layer thickness on the Fildes Peninsula, King George (Waterloo) Island, Western Antarctica are presented for the period of 2007 to 2019. The dynamics of the main meteorological parameters affecting the active layer thickness is determined. The numerical experiments based on the mathematical model are performed to determine the effects of various parameters on the active layer thickness. The calculated and measured values of the active layer thickness are compared. The thermal instability of permafrost in the study area in some years with high (above the means) summer air temperature is demonstrated. The climate cooling which started in the region in the recent years has increased the number of years with the positive ice mass balance. However, the positive ice mass balance has not yet become a dominant factor against a background of the negative balance in the previous years.

Summary Comparison of two methods of measurements of snow cover thickness on the glacier Austre Gronfjordbreen, Svalbard was performed in the spring of 2014. These methods were the radar (500 MHz) observations and standard snow surveys. Measurements were conducted in 77 different points on the surface of the glacier. A good correlation (R 2 = 0.98) was revealed. In comparison with the data of snow surveys, the radar measurements show a similar but more detailed pattern of the distribution of the snow cover depth. The discrepancy between the depths of snow cover on maps plotted from data of both methods did not exceed 30 cm in most parts of the glacier. The standard error of interpolation of the radar data onto the entire glacier surface amounts, on average, to 18 cm. This corresponds to the error of radar measurements of 18.8% when an average snow depth is about 160 cm and 9.4% at its maximum thickness of 320 cm. The distance between the measurement points at which the spatial covariance of the snow depth disappears falls between 236 and 283 m along the glacier, and between 117 and 165 m across its position. We compared the results of radar measurements of the pulse-delay time of reflections from the base of the snow cover with the data of manual probe measurements at 10 points and direct measurements of snow depth and average density in 12 snow pits. The average speed of radio waves propagation in the snow was determined as V cr = 23.4±0.2 cm ns −1 . This magnitude and the Looyenga and Kovacs formulas allowed estimating the average density of snow cover ρ L = 353.1±13.1 kg m −3 and ρ K = 337.4±12.9 kg m −3 . The difference from average density measured in 12 pits ρ av.meas = 387.4±12.9 kg m −3 amounts to −10.8% and −14.8%. In 2014, according to snow and radar measurements, altitudinal gradient of snow accumulation on the glacier Austre Gronfjordbreen was equal to 0.21 m/100 m, which is smaller than the average values (0.35 m/100 m). According to the results of snow measurements of 2011–2014, the average thickness of the snow cover on the glacier Austre Gronfjordbreen was by 17 cm greater than in 1979. In the very snowy year 2012, it was higher by 21.5 cm in comparison with the year 1979, and its spatial variability (standard deviation σН) had increased by 25.6 cm. Estimates of spatial and temporal variability of snow cover depth will be used to analyze the hydrothermal state of the glacier and its changes with regard to revealed features and climatic trends.

In 1966-2010, snow surveys were simultaneously performed in forests and fields on the Russian plain territory. This made it possible to analyze characteristics of snow storages on fields and in forests as well as a dynamics of them under the present-day climate changes. Data of 81 weather stations located on the territory were used. According to data of these stations for the period 2001–2010 we obtained the following estimates for the maximal snow storage values, on average: for 20 stations located on the European territory of Russia to the north of 60° N –167 mmin forests and 162 on fields; for 44 stations to the south of 60° N – 118 and116 mm, respectively; for 10 stations in the south of West Siberia – 125 and107 mm; and for 7 stations in the East Siberia – 64 and70 mm. As one can see the last region is characterized by the opposite relation between forest and field conditions. Comparison of these values with similar data for the period 1966-2000 demonstrated that maximal snow storages decreased in forests by 7% but in fields they increased by 2%. The ratio of the maximum snow storage in the forest to their value in the field (i.e. a coefficient of snow reserve) for the periods 1981–1990, 1991–2000, and 2001–2010 are 1.15; 1.11 and 1.03, respectively. One of the reasons for the equalization of snow storage in forest and field may be changes of intensity and duration of snowstorms. In the calendar winters of 2001-2010, the average number of observations at weather stations with wind speeds over 10 m/s decreased relative to 1966-2010: in the European part of Russia by factor of 8.9 times, and in Western and Eastern Siberia – by 2.0 and 1.9 times, respectively. In the European part ofRussia, the number of observation periods when wind speed from 6 to 10 m/s was observed decreased by 1.9 times.

Effect of the snow thermal resistance on soil freezing is comparable to the influence of mean temperature in the cold period. Available values of the effective thermal conductivity of snow have been analyzed and compared with experimental data on snow cover with different structure collected in Moscow region. Effect of ice crusts and depth hoar layer on the thermal resistance of snow cove have been illustrated with West Spitsbergen and Moscow region examples. Neglect of snow cover stratigraphy in estimations of thermal conductivity was demonstrated to overrate is more than by half. As a result, the estimated rate of soil freezing might be higher than actual one, and therefore transition to the dangerous soil weakening and the beginning of permafrost degradation might past unnoticed.

Представлены результаты оценки состояния грунтов при изменении метеопараметров по данным наблюдений в 2005 и 2006 гг.The changes in permafrost are estimate in view of change of meteorological elements in the area of Bellinsgausen Station, Antarctica. The analyses of variability of air temperature, precipitations, wind velocities and other meteorological parameters are given for the last 10 years. For that period the summer temperatures and solid precipitations are diminished. Calculations show that degradation of permafrost under the modern climatic conditions does not occur. The formation of a talik in permafrost can begin when the mean summer air temperature grows up to 2,6С.