Ice and Snow (E-Journal) / Лёд и Снег
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Капельное вымораживание солёной воды при зимнем дождевании
Get PDFThe purpose of the research is to evaluate the efficiency of winter sprinkling for desalination of seawater. The ice fraction in an individual drop and in a stream of drops in a free fall is estimated. At the air temperatures of −10 and −40 °C, the percentage of ice in a stream of water drops with a mineralization of 35 g/l may amount to 12 and 39%, respectively. Calculations showed that when producing porous ice from water with a mineralization of 35 g/l by means of sprinkling at the same air temperatures, the productivity of the DDN–70 sprinkler system will be equal to 670 (−10 °C) and 2190 (−40 °C) tons of ice per day. When the fraction of ice in the drops of stream increases, the salinity of unfrozen water grows too, and this results in increasing of the porous ice salinity. Experiments did show that at mineralization of the source water of 10 g/l, the moisture content of porous ice amounts 12%, while in the ice frozen from seawater it is 23%. The humidity of a salt porous ice makes influence on the desalination efficiency. At a moisture content of porous ice of 12% and melting of 30% of its volume, the mineralization of the remaining part is 4 times less than that at the a moisture content of 23%, but if the melting reaches 50% of the volume it is 16 times. It was found that with growth of salinity of frozen water the performance of sprinkling and efficiency of desalinization decrease. However, it should be noted that when using sea water with a salinity of 35 g/l after melting of 50% of the porous ice volume, the salinity of the remaining part of water will amount approximately 1 g/l, and after appropriate sanitary and hygienic treatment, it can be used for drinking water supply. It is important also that such water will contain in sufficient amounts the necessary microelements.На основании математического моделирования определена динамика замерзания отдельной капли воды и дана оценка доли льда в капельном факеле. Рассчитана производительность намораживания пористого льда в зависимости от солёности намораживаемой воды и размера капель воды. Определена динамика опреснения массивов пористого льда разной солёности. Впервые оценена эффективность применения зимнего дождевания для опреснения морской воды
Изменения высоты поверхности и баланс массы ледникового купола Академии Наук на Северной Земле
Get PDFWe have determined the surface-elevation change rates of the Academy of Sciences Ice Cap, Severnaya Zemlya, Russian Arctic, for two different periods: 2004–2016 and 2012/2013–2016. The former was calculated from differencing of ICESat and ArcticDEM digital elevation models, while the latter was obtained by differencing two sets of ArcticDEM digital elevation models. From these surface-elevation change rates we obtained the geodetic mass balance, which was nearly identical for both periods, at −1,72±0,67 Gt a−1, equivalent to −0,31±0,12 m w.e. a−1 over the whole ice cap area. Using an independent estimate of frontal ablation for 2016−2017 of −1,93±0,12 Gt a−1 (−0,31±0,12 m w.e. a−1), we get an estimate of the climatic mass balance not significantly different from zero, at 0,21±0,68 Gt a−1 (0,04±0,13 m w.e. a−1), which agrees with the near-zero average balance at a decadal scale observed during the last four decades. Making an observationally-based assumption on accumulation rate, we estimate the current total ablation from the ice cap, and its partitioning between frontal ablation, dominated by calving (~54%) and climatic mass balance, mostly surface ablation (~46%).На основе разновременных ЦМР установлены скорости изменения высоты поверхности ледникового купола Академии Наук на Северной Земле за два периода: 2004−2016 и 2012/2013−2016 гг. и определён геодезический баланс его массы (−1,72±0,67 Гт/год). Сделан расчёт климатического баланса массы (0,21±0,68 Гт/год) и полной абляции (−3,18 Гт/год) ледника, где на отёл приходится ≈54%, а на поверхностную абляцию – ≈46%
Изотопный состав и регионы-источники зимних осадков в Надымской низменности
Get PDFAccording to the forecast of IPCC (Intergovernmental Panel of the Climate Change), an increase in precipitation is expected in this century in the Arctic. The main reason is intensification of evaporation from waters of the Arctic Ocean opening due to the intensive melting of sea ice. It is supposed that these changes will be most severe in winters in the Arctic regions, which are subject to significant anthropogenic load. In this respect, the intensively developed Nadym Lowland may be considered as a promising area for researches. The results of our study showed that the circulation conditions (primarily cyclones coming from the North Atlantic under the Eastern (E) circulation form of the G.Ya. Vangenheim–A.A. Girs classification) significantly influence on the isotopic composition of precipitation in this region. Thus, in the cold period of 2016–2017, the isotopic composition of precipitation changed for δ18О by 21 ‰, and for δD by 167 ‰ (weighted average values δ18О = −22.3 ‰, δD = −172.6 ‰, and dexc = 5.6 ‰). The use of the dew point temperature at the moment of precipitation in the calculations of the isotopic-temperature dependences allows obtaining the following coupling equation: δ18О = 0.67Tdp − 15.2 (R2 = 0.67). On the basis of the joint analysis of synoptic, trajectory and isotopic data, the main regions-sources of atmospheric moisture, precipitated in the Nadym Lowland during the cold period of 2016–2017, were determined. The major contributions were made by the Atlantic Ocean (35.7%), the North Atlantic Ocean and the Arctic Ocean (30.4%), and the Black Sea-Caspian region (20%). The last one is characterized by the most weighted isotopic composition. Inland source regions have contributed the least to precipitation (slightly larger 10%), and their lightweight isotopic composition is related to cryogenic fractionation.В результате совместного анализа синоптических, траекторных и изотопных данных определены основные регионы‑источники поступления атмосферной влаги, выпавшей в виде осадков в Надымской низменности. Наибольший вклад вносит Атлантический океан (35,7%), меньше – северная часть Атлантического океана и Северный Ледовитый океан (30,4%), а также Черноморско‑Каспийский регион (20%) и внутриконтинентальные регионы (немногим более 10%)
Особенности контактного разрушения льда
Get PDFThe formation of an intermediate layer under hydrostatic compression at a shear appearing due to the action of converging and diverging fronts of stress momentums (pulses) is considered. Continuous monitoring of deformational changes in the structure of ice was carried out using acoustic methods. The features of contact ice breaking in the diverging fronts of stress pulses are considered by the example of the slow impact of a rigid spherical indenter on an ice plate simulating half-space. Using the piezoelectric accelerometer, an oscillogram of the impact was recorded and a generalized dependence of the reduced stress on the reduced instantaneous velocity of the impact (semi-cubic parabola) was obtained. It is established that under conditions of the experiment (smooth convex indenter surface and icy half-space) a thin intermediate layer is formed, the properties of which determine the physical similarity in the family of curves «instantaneous force-instantaneous velocity». A rheological model with due regard for the change in the microstructure of ice during the impact is proposed. Quantitative determinations of the deformation changes in structure of solid ice samples were performed under intensive plastic deformation in a matrix with a profile similar to the Laval nozzle. The deformations created by the piston caused forced vibrations in the ice. The working surface of the piston in the form of an ellipsoid together with the smooth walls of the matrix and the reverse cone created conditions for parametric resonance and the formation of fronts of highfrequency stress pulses. Under influence of these pulses, zones with a superplastic fine-crystalline structure of ice (cumulative effect) were formed in ice. In the outlet cylindrical channel, a flow around an obstacle of the ice with the structure of an intermediate layer (dynamic viscosity 20 MPa s) and the distribution of velocities of motion over the channel cross section were studied. The obtained results can be used to simulate the processes of contact destruction of deep rocks by a support or an ice-resistant platform loaded with an ice field.Проанализированы закономерности эволюции структуры пресноводного льда в условиях гидростатического сжатия при сдвиге под действием сходящихся и расходящихся фронтов импульсов напряжений. Исследовано обтекание льдом препятствия, распределение скоростей в цилиндрическом канале, формирование промежуточного слоя вблизи поверхности шарового индентора при медленном ударе. Количественно определены деформационные изменения структуры льда непосредственно в процессе контактного разрушения
Изменчивость морского льда в Арктике по данным Арктического портала
Get PDFThe Arctic Portal of the Laboratory of Satellite Oceanography of the Russian State Hydrometeorological University is an open geo-informational system designed for operational monitoring of the sea ice–ocean–atmosphere system in the Arctic. Possibilities to use the Arctic Portal for the Arctic sea ice monitoring on the basis of satellite data, as well as the types of satellite measurements suitable for studying the properties of sea ice: active and passive microwave data; data of spectral radiometers in the infrared (IR) and visible ranges are considered. Every type of satellite data has certain limitations. For the study of sea ice the most suitable are the all-season remote sensing data – measurements of microwave instruments, independent of clouds and time of a day. Existing in the world resources of the sea ice maps and satellite data on sea ice are either closed for users or limited in their informational content. Several types of satellite data are currently available on the Arctic portal: Sentinel-1 synthetic aperture radar (SAR) images, 8-day averaged MODIS reflectivity data, optical and IR MODIS data of original time and spatial resolution, Norwegian Meteorological University sea ice maps, and data on consolidation of sea ice, based on passive microwave radiometer measurements. Some data is additionally available in the test mode. The effectiveness of combined use of various satellite data on the sea ice is proved by the examples of sea ice analyses.Представлены возможности Арктического портала (геоинформационного сервиса) для мониторинга ледяного покрова Арктики на основе спутниковых данных. Дан обзор основных типов спутниковых инструментов, позволяющих изучать морской лёд. Обоснована эффективность совместного применения результатов обработки разных спутниковых данных, имеющихся в среде геосервиса
Связь между переносом метана в атмосферу и разрушением ледяного покрова Карского моря: спутниковые данные за 2003–2019 гг.
Get PDFSatellite spectrometers operating on the outgoing long-wave IR (thermal) radiation of the Earth and placed in sunsynchronous polar orbits provide a wealth of information about Arctic methane (CH4) year-round, day and night. Their data are unique for estimating methane emissions from the warming Arctic, both for land and sea. The article analyzes concentrations of methane obtained by the AIRS spectrometer in conjunction with microwave satellite measurements of sea ice concentration. The data were filtered for cases of sufficiently high temperature contrast in the lower atmosphere. The focus is on the Kara Sea during autumn-early winter season between 2003 and January 2019. This sea underwent dramatic decline in the ice cover. This shelf zone is characterized by huge reserves of oil and natural gas (~90% methane), as well as presence of sub-seabed permafrost and methane hydrates. Seasonal cycle of atmospheric methane has a minimum in early summer and a maximum in early winter. During last 16 years both summer and winter concentrations were increasing, but with different rates. Positive summer trends over the Kara Sea and over Atlantic control area were close one to another. In winter the Kara Sea methane was growing faster than over Atlantic. The methane seasonal cycle amplitude tripled from 2003 to 2019. This phenomenon was considered in terms of growing methane flux from the sea. This high trend was induced by a fast decay of the sea ice in this area with ice concentrations dropped from 95 to 20%. If the current Arctic sea cover would decline further and open water area would grow then further increase of methane concentration over the ocean may be foreseen.Проанализированы ИК спутниковые данные о концентрации метана в слое атмосферы 0–4 км над Карским и Баренцевым морями в сравнении с микроволновыми спутниковыми измерениями ледяного покрова Карского моря. За последние 16 лет амплитуда сезонных вариаций метана над северной частью Карского моря выросла в 3 раза, а площадь поверхности того же района, свободная от льда, увеличилась в 4 раза. Сделан вывод о значительной роли ледяного покрова в экранировании потока метана в атмосферу
Сокращение ледников северной части Срединного хребта на Камчатке в период с 1950 по 2016–2017 гг.
Get PDFThe Northern part of the Sredinny (Middle) Range is the largest glaciation area in Kamchatka in terms of the numbers and areas of glaciers. As of 2016–2017, there were 465 glaciers in this area with a total area of about 255±17 km2. Amongst the morphological types, the cirque (corrie), slope, and corrie-valley glaciers predominate (64%), but more than half of the total area (54%) is covered by the corrie-valley and transaction glaciers. The average area of glaciers over this region is 0.55 km2, while for the transection ones it is 8.3 km2. The main part (77.4%) of the glaciers in the region is located in the altitude range of 1200–1800 m. The firn line on both slopes of the Central Range lies within the altitude range of 880–1910 m. Analysis of changes in the size of the recent glaciation in comparison with the data of the mid-twentieth century indicates that the trend towards its reduction, established in the second half of the twentieth century, remains at the present time. The loss of the area of glaciers in the region registered in the USSR Glacier Inventory (1950), by 2016–2017 amounts to almost 125 km2 (35.6%). Note, that losses for the first 15 years of the twenty-first century turn out to be approximately equal to the total sum of losses for second half of the twentieth century. It means that at the beginning of the twenty-first century the rate of reduction of glaciers is 4.3 times greater, i.e. about 1.45% of the area per year. The glaciers of the South-Eastern (62.9%) and Southern (43.6%) exposures reduced the most (significantly more than others). Loss of the total area was the greatest in small glaciers with sizes smaller 0.1 km2 (> 70%) and the smallest in large glaciers exceeding 5 km2 (< 11%). The process of disintegration of large glaciers into smaller ones did also accelerate, that increased total number of glaciers. The increase in the rate of glaciers area reduction in the region at the beginning of the twenty-first century was mainly caused by the rise in summer air temperatures, that also intensified in these years. Similar values of the relative reduction of glacier areas are observed in the North Chui Range (Altay), in the Bernese and Pennine Alps, in the Polar Ural, in the Nordenskjold Land (Svalbard), etc.Приводятся данные о размерах, морфологии и высотных параметрах ледников северной части Срединного хребта на Камчатке в 2016–2017 гг. Дана оценка изменения оледенения района за три временных периода: с 1950 по 2016–2017 гг., c 1950 по 2002 гг., c 2002 по 2016–2017 гг. Установлены резкое увеличение скорости сокращения ледников с 2002 по 2016–2017 гг. (1,45% площади в год) по сравнению с 1950–2002 гг. (0,34% площади в год), а также интенсификация распада ледников (вместо 152 ледников, зарегистрированных во второй половине ХХ в., обнаружены 187 ледников в 2002 г. и 249 ледников в 2016–2017 гг.)
Тепловые деформации и радиояркостная температура ледяного покрова пресных водоёмов
Get PDFThe paper presents results of experimental studies of the deformation of a freshwater ice cover. The works were carried out on the Lake Arakhley located in the Trans-Baikal Region, where winters are characterized by small amount of snow and sharp daily changes in the air temperature reaching 25 °C. As a result of this, the temperature gradient of the surface layer of the ice cover exceeds 1 °C/cm. This causes formation of the dry cracks in the upper layers of the cover. The authors measured daily variations in the temperature of the ice cover at various depths by its thickness. Results of the experiment made possible to propose the explanation for the formation of dry cracks and the depth of them, which reaches 20 cm in the Trans-Baikal Region. According to studies using a differential strain gauge, it was found that the upper layer of the ice cover is in a stressed state due to changes in its temperature. This is evident from the fact that when the temperature of the upper layer of ice changes, the distance between the reference points slightly changes too. When the air temperature approaches the temperature of the «ice–water» phase transition, the ice cover is unloaded. We assume that the dry cracks can also be formed when the stress state of ice is released at even lower temperatures. Interest in these structural changes had been arisen in connection with possible variations in the electromagnetic properties of the ice cover, which can be detected by non-contact radio wave measurements. These variations result from the presence of a quasiliquid layer on the surfaces of dry cracks (together with hoar-frost and snow in them), which can exist down to a temperature of −90 °C. Its presence increases the complex relative permittivity of a medium consisting of a solid (ice) and a liquid phase (water film). Calculations of the radiometric temperature within the centimeter range in a flat-layer non-isothermal medium have shown that the presence of dry cracks in the ice cover increases radio temperature up to 5 K on both, vertical and horizontal polarizations. This value is recorded during radiometric measurements, and this factor should be taken into account during the remote sensing of freshwater ice covers.Проведены экспериментальные исследования сухих трещин, вызванных вариациями температуры верхних слоёв в пресном ледяном покрове озера Арахлей (Забайкальский край). С использованием дифференциального датчика деформации установлено, что верхний слой ледяного покрова из-за изменения его температуры находится в напряжённом состоянии. При достижении предела текучести происходит быстрая разгрузка напряжений с образованием сухих трещин. Расчёты радиояркостной температуры в сантиметровом диапазоне с использованием плоскослоистой неизотермической среды показали увеличение этой температуры до 5 К при наличии сухих трещин в ледяном покрове
Оценка потенциала развития ледниковых озёр на Центральном Кавказе
Get PDFGlacier mass loss and consequent terminus retreat lead to formation and growth of glacier lakes. In Caucasus outbursts of glacial lakes formed in recent decades have led to human casualties and significant damage. In this study the location and volume of the potential glacier lakes in Central Caucasus was estimated based on ground and airborne GPR data, as well as using results of global ice thickness modelling. Selected glaciers are located in the Adyl-Su and Gerkhozhan-Su valleys as well on the southern and north-eastern slopes of Elbrus. The methodology was tested by retrospective modeling of Bolshoy Azau and Djikiugankez glaciers bed topography using 1957 topographic map. Seven existing lakes were predicted by the hydraulic potential in the areas where glaciers disappeared by 2017. Six overdeepenings on Djikiugankez glacier bed as of 1957 are currently absent, which might be related to the model uncertainties and the original DEMs errors, as well as to possible filling of lakes by sediments. Retrospective modeling of the Bashkara glacier bed topography based on SRTM DEM (2000) showed significant growth potential of the existing lake Lapa. Retrospective modeling of the Kaayarty glacier bed topography has not provided a clear answer whether the subglacial lake outburst flood was a trigger for catastrophic debris flow formation during the summer of 2000. In case of total disappearance of Bolshoy Azau, Djikiugankez and Bashkara glaciers at least 11 new lakes with total area of about 1.7 km2 and an average depth of 8 m will form. While the deepest lake will be formed at the ablation zone of Bolshoy Azau glacier (at elevation 3100–3400 m a.s.l.) the largest in area (1 km2) glacial lake will appear at the Djikiugankez snout with maximum depth of 40 m and mean depth of 7.2 m. The simulation also showed that subglacial lakes of different number and size may also exist under studied glaciers. Our estimates may contain uncertainties due to low resolution of airborne GPR data and the lack of GPR data for Kayaarty glacier, DEM and ice thickness model errors. Detailed ground-based radar survey will enable the assessment of the size and volume of the potential subglacial lakes.На основе данных радиолокационного зондирования и моделирования оценены объём и площадь потенциальных озёр, которые могут сформироваться на месте отступающих ледников в Приэльбрусье. Методика протестирована путём ретроспективного моделирования ложа ледников по материалам 1957 и 2000 гг. Установлено, что площадь потенциальных озёр, угрожающих объектам инфраструктуры, может достичь 1,7 км2, а объём – 130 млн м3
Реконструкция средних температур января в раннем голоцене на северо-востоке Большеземельской тундры
Get PDFThe aim of the study was to establish the period of accumulation of peatland with ice wedges near Vorkuta town based on series of calibrated radiocarbon dates, to anchor in time the isotope-oxygen curve of syngenetic ice wedge from peatland and to reconstruct the mean January air temperature for the appropriate Holocene period. Analysis of a series of 14C dates showed that peatland near Vorkuta was actively formed between 10.5 and 6 cal. ka BP. Winter conditions in the Vorkuta area were quite severe, that favored to frost cracking of the peatland and syngenetic growth of ice wedges within the drier sites and peat-soil wedges within the watered sites. Ice wedge growth was the most active within the Greenlandian Stage of Holocene, between 10,5 and 9,7 cal. ka BP, the reconstructed mean January air temperature for this period varied between −23 and −25 oC; currently, such temperatures are recorded only during the coldest winters.Вблизи г. Воркута процессы заболачивания и образования торфа начались в первой половине гренландского периода голоцена – около 11–10 тыс. калиб. лет назад. Завершилось формирование торфяника 3–2 тыс. калиб. лет назад. Время активного формирования в торфянике сингенетических повторно-жильных льдов приходится на период между 10,5 и 9,7 тыс. калиб. лет назад, когда среднеянварская температура воздуха варьировала между −23 и −25 oC