Ice and Snow (E-Journal) / Лёд и Снег
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Пространственная изменчивость толщины снежного покрова на горном склоне (архипелаг Шпицберген)
Get PDFThe study was carried out to estimate the spatial variability of snow cover depths in avalanche centers of the mountain slopes of Svalbard. Accounting for the variability is necessary for monitoring the snow cover depths in the avalanche centers and evaluating the snow cover stability on the slope. The main tasks of the work were to evaluate the variability parameters and compare them with similar estimates obtained in other regions. In contrast to conventional snow surveys, thickness measurements were carried out more frequently (with resolution of every 1 m) in profiles (eight profiles in total), not exceeding the characteristic linear size of the avalanche origin zone (up to 100 m2). Spatial variations of snow cover thickness in each profile are considered as the realization of a random process. Data of the spring measurements of 2015 were used to estimate the mathematical expectations, variances, and autocorrelation functions of the snow cover depth on the Mount Olav slopes. Comparison of parameters of variability with those obtained in different mountain regions of Russia with the similar underlying surface, shows that the variability on Svalbard are the most similar to the variability in the Khibiny Mountains. Although the scattering and coefficients of variation obtained in the Khibiny Mountains are slightly larger, the spatial coherence of the snow cover depths is the lowest on Svalbard. Estimates of the correlation radii are within the range of 2–6 m. With such variability any deterministic estimation of spatial snow accumulation with the help of remote measurement stakes is impossible. The obtained parameters of the spatial statistical structure of the snow cover thickness allow using statistical modeling for the interpretation of point measurements. In that case, uncertainty of snow cover thickness data in places where measurements were not made will be reflected in their probabilistic estimation.Пространственные изменения толщины снежного покрова на горных склонах Шпицбергена рассматриваются как реализации случайных процессов. Параметры этих процессов оценены на основании специальных снегосъёмок. Cтатистические связи толщины снега в разных точках склона резко падают с расстоянием между этими точками. По сравнению с Западным Тянь-Шанем, Кавказом, Алтаем, Байкальским хребтом и Хибинами изменчивость снега в горах Шпицбергена самая высокая и близка к Хибинам
Геохимия льдов бугров пучения в долине р. Сенца (Окинское плоскогорье, Восточный Саян)
Get PDFTe authors examined the chemical composition of underground ice sampled from the frost mounds located in the loose (unconsolidated) sediments of the Sentsa River valley (Oka plateau, Eastern Sayan) with the purpose of reconstruction the formation history of these cryogenic creations. Numerous frost mounds of various sizes are mainly composed of alternating icy loams, sandy loams, and lenses of pure ice. Samples of underground ice taken in the outcrops of the river ledges and cores from wells together with samples of river and lake waters were analyzed by traditional hydrochemical techniques (methods) in the center "Geodynamics and geochronology" (Institute of the Earth's Crust of the Siberian branch of RAS, Irkutsk). It was found that the chemical composition of pure ice melts from lenses and layers of the frost mounds is hydrocarbonate calcium (HCO3 Ca, SO4-HCO3 Ca and NH4-HCO3 Ca) with mineralization of 6.5 – 15.6 mg/L, pH = 5.6÷6.1. Mineralization of melts of texture-forming ice, taken from icy ground (i.e. with fractions of enclosing loams) was much higher – from 50 to 792.5 mg/L. River and lake water is ultra-fresh with 99–132 mg/L salinity, and according to geochemical type it is hydrocarbonate calcium (HCO3 Ca). Te specifc features of chemical composition of the underground ice (high content of ammonium salts and sulfates) depend on a water-rock interaction, the presence of organic matter in the loose (unconsolidated) sediments and a repeated volcanic activity in the late Pleistocene–Holocene. Te frost mounds are confned to a lacustrine sediments area in the backwater zone that was formed by the Late Pleistocene terminal moraine. Teir formation in the Holocene took place as a result of segregational ice formation during freezing of water-saturated lake sediments, and, presumably, repeated injections of underground waters of the under-channel and floodplain aquifers hydraulically connected with river waters. Tus, the genesis of the studied frost mounds is probably a mixed segregation-injection process.Многочисленные бугры пучения в долине р. Сенца на Окинском плоскогорье в Восточных Саянах сложены переслаивающимися льдистыми суглинками, супесями и линзами чистого льда. Установлено, что расплавы текстурообразующих льдов ультрапресные и пресные, по химическому составу – гидрокарбонатные, сульфатно-гидрокарбонатные и аммонийно-гидрокарбонатные кальциевые. Специфика химического состава подземных льдов обусловлена взаимодействием в системе вода – порода, наличием органики в рыхлых отложениях и неоднократной активизацией вулканизма в позднем плейстоцене–голоцене
Оценка эволюции ледниковых систем Северо-Востока России по данным регулярного метеорологического архива
Get PDFA methodical approach is proposed for calculating the equilibrium line altitude HELA of glacier systems (on the example of the Northeastern Russia) on the basis of the characteristics that determine it in time and space: from the archive of temperature and precipitation at the grid points (the UDel archive, Delaware University). This data is used in the equation of mass balance of the glacier systems for the calculation of its components. As a result, the output is the inter-annual series of deviations of HELA from the mean value and the ratio between accumulation and solid precipitation in the regular grids over the glacial systems. By the longterm series of the HELA deviations the periods of minimum and maximum HELA state were revealed for various glacial systems, as well as linear trends of these series. This made us possible to evaluate the HELA trends in the future using the linear regression method. The sensitivity of the method of the initial parameters – the mean values of the summer air temperature, solid precipitation and the HELA value, received independently, have been estimated. Thus, the method allows detailing the HELA changes in space with the resolution of the archive used, and in time for each year of the selected climatic period.Предлагается методический подход для вычисления высоты границы питания HELA ледниковых систем (на примере Северо-Востока России) по архивным данным о температуре и осадках в узлах регулярной сетки 0,5° × 0,5°. По связи между архивными твёрдыми осадками и аккумуляцией для десяти ледниковых систем вычислены межгодовые ряды изменения HELA за 1949–2014 гг. и их линейные тренды для прогноза этой величины
Динамика ледового режима Азовского моря в XX–XXI вв.
Get PDFThe ice regime of the Sea of Azov over the period of 20th and 21nd centuries was investigated using the author's GIS «The ice regime of the Southern Seas of the Russia». The long-term dynamics of the ice cover, duration of the ice stay as well as beginning and end of the ice period were considered. It has been found that for the period of 1950–2015 the average annual value of the Azov Sea ice cover area is 33%, while the average area of the fast ice is 6.3% of the total area of the sea. Value of duration of the ice cover stay on the sea surface has been refined, and this value is 115 days near the hydro-meteorological station (HMS) Taganrog and 63 days near the HMS Kerch. The typification of winters according to the degree of severity was performed on the basis of data from three coastal meteorological stations: Taganrog, Genichesk, and Kerch. Winters of moderate type were shown to be prevailing during the entire analyzed period. Totally, 15 severe, 70 moderate and 40 mild winters were isolated for the period 1883-2015, while for 1950–2015 the statistics was the following: 9 severe, 43 moderate, and 14 mild winters in Taganrog, and 10 severe, 40 moderate, and 16 mild winters in Kerch.Рассматривается многолетняя динамика ледового режима Азовского моря: ледовитость, сплочённость, продолжительность, начало и конец ледового периода. В XX–XXI вв. ледовитость Азовского моря в среднем составляет 33%, продолжительность ледостава сокращается. Преобладают зимы с умеренными температурными условиями. Разработана классификация зимних периодов, объединившая все ледовые характеристики и типизацию зим по степени суровости, согласно которой в Азовском море также преобладают зимние периоды умеренного типа
В ПОИСКАХ ДРЕВНЕЙШЕГО ЛЬДА АНТАРКТИДЫ
Get PDFOne of the key priority tasks for the international Antarctic community is drilling and studying old Antarctic ice with age exceeding 1 million years in order to investigate possible reasons for the Mid-Pleistocene Transition. During the 2017–2018 austral season at Vostok Station, we carried out microscopic study of geometrical properties of the crystalline inclusions of air hydrates in ice core samples from boreholes 5G‑3 (Vostok) and DC2 (EPICA DC) in depth intervals where the age of the ice exceeded 400,000 years. The obtained data confirmed the existence of a robust linear relationship between the mean radius of the hydrates and the age of the ice in the bottom part of the East Antarctic ice sheet, and will be useful for further development of the new dating technique based on the phenomena of hydrate growth in polar ice. Preliminary, the age of the atmospheric ice bedded at Vostok at a depth of3538 m, inferred from the data on the size of the hydrates, amounts to 1.3±0.17 million years. The existence of ice older than 1 million years in the vicinity of Vostok implies that in the area of Ridge B, where the ice flow line which passes through Vostok Station originates, even older ice, with undisturbed stratigraphy, may exist. It would be desirable therefore to carry out a glacio-geophysical traverse to Ridge B in order to implement a detailed study of Dome B area aimed at identifying the most suitable site for a new deep drilling of the Antarctic ice sheet.Сделан краткий обзор деятельности международного антарктического сообщества по поиску древнего льда в Антарктиде. Приведены предварительные результаты работ, полученные на станции Восток в период 63-й Российской антарктической экспедиции, которые подтверждают, что возраст льда в уже полученном на станции керне превышает 1 млн лет. Сформулированы первоочередные задачи дальнейших исследований древнего антарктического льда на станции Восток и в районе Ледораздела В
Использование спутниковой информации для обнаружения айсбергов и оценки айсберговой угрозы
Get PDFTe methods of satellite monitoring of dangerous ice formations, namely icebergs in the Arctic seas, representing a threat to the safety of navigation and economic activity on the Arctic shelf are considered. Te main objective of the research is to develop methods for detecting icebergs using satellite radar data and high space resolution images in the visible spectral range. Te developed method of iceberg detection is based on statistical criteria for fnding gradient zones in the analysis of two-dimensional felds of satellite images. Te algorithms of the iceberg detection, the procedure of the false target identifcation, and determination the horizontal dimensions of the icebergs and their location are described. Examples of iceberg detection using satellite information with high space resolution obtained from Sentinel-1 and Landsat-8 satellites are given. To assess the iceberg threat, we propose to use a model of their drif, one of the input parameters of which is the size of the detected objects. Tree possible situations of observation of icebergs are identifed, namely, the «status» state of objects: icebergs on open water; icebergs in drifing ice; and icebergs in the fast ice. At the same time, in each of these situations, the iceberg can be grounded, that prevents its moving. Specifc features of the iceberg monitoring at various «status» states of them are considered. Te «status» state of the iceberg is also taken into account when assessing the degree of danger of the detected object. Te use of iceberg detection techniques based on satellite radar data and visible range images is illustrated by results of monitoring the coastal areas of the Severnaya Zemlya archipelago. Te approaches proposed to detect icebergs from satellite data allow improving the quality and efciency of service for a wide number of users with ensuring the efciency and safety of Arctic navigation and activities on the Arctic shelf.Рассмотрены методы обработки оперативной спутниковой информации об айсбергах. Применённая методика обнаружения айсбергов основана на статистических критериях поиска градиентных зон при анализе двухмерных полей. Использование методик обнаружения айсбергов по спутниковым радиолокационным данным и снимкам видимого диапазона показано на материалах мониторинга прибрежных районов Северной Земли
Региональные особенности изменения зимних экстремальных температур и осадков на территории России в 1970–2015 гг.
Get PDFTe space-time dynamics of the occurrence of winter extreme events is investigated on the territory of Russia in 1970-2015 on the basis of daily observations at weather stations. It was found that a whole on the territory a noticeable increase in the occurrence of days with extremely high daily temperatures and daily precipitation and a decrease in the occurrence of extremely cold days was noted. Te most noticeable changes happened in the European part of Russia, where at the beginning of the XXI century occurrence of the extremes was greater than during the previous thirty years. Note also that at the beginning of XXI century in Southern Siberia increase of occurrences of both daily maximum and daily minimum temperature was concurrent. Tis combination appears to be caused by the increase in temperature variability in the region due to the alternation of winters with extreme frosts and warmer and wet winters. Te increase in the frequency of extremely high temperatures in the European part of Russia could have been caused by both general warming and the increased influence of AMO. An increase in the frequency of extreme high and low temperatures in the south of Siberia may be due to the formation of an anticyclonic circulation anomaly with a center near the coast of the Kara Sea, which is responsible for advection of cold air masses from the northeast. As well as cyclonic formation in southern Siberia, along the eastern periphery of which temperate latitudes can receive anomalously warm air from the subtropics.Исследована повторяемость экстремальных явлений зимой на территории России в 1970–2015 гг. на основе суточных данных наблюдений на метеостанциях. Отмечен рост повторяемости дней с высокими суточными температурами, суточными суммами осадков и уменьшение морозных дней. Самые большие изменения наблюдаются в Европейской части России. На юге Сибири в начале XXI в. одновременно увеличилась повторяемость морозных и тёплых дней, а также дней с экстремальными зимними осадками
Оценка коэффициента теплопроводности снега по его плотности и твёрдости на Западном Шпицбергене
Get PDFThe results of experimental investigation of thermal conductivity of snow on the Svalbard archipelago in the conditions of natural occurrence are considered. The observations were carried out in the spring of 2013–2015 in the vicinity of the meteorological station «Barentsburg». The obtained data were processed using the Fourier equation of thermal conductivity that allowed determination of the coefficient t of thermal conductivity of the snow with different structure and density. The thermal conductivity of snow depends on the contacts between ice crystals. The larger the contact area, the better the heat transfer from one layer to another. But the strength characteristics of snow, and especially its hardness, depend on the bonds between ice crystals, so the thermal conductivity and hardness of snow depend on the structure of snow. Note, that measurements of snow hardness are less laborious than measurements of its thermal conductivity. For layers of snow cover of different hardness the relationship between snow thermal conductivity and its density has been established. To verify the reliability of the approach to the determination of snow thermal conductivity, numerical experiments were performed on a mathematical model, which did show good convergence of the results. The obtained formulas for the coefficient of thermal conductivity of very loose, loose, medium and hard snow (according to the international classification of seasonal snow falls) are compared with the data of other studies. It was found that when the snow density is within the range 0.15–0.40 g/cm3 these formulas cover the main variety of thermal conductivity of snow. This allows estimating the coefficient of thermal conductivity and to determine the thermal resistance of snow cover in the field by measuring the density and hardness of different layers of snow.На основе измерений температурного профиля в снежной толще на Западном Шпицбергене путём решения обратной задачи уравнения теплопроводности определены значения коэффициента теплопроводности снега. Для снега разной твёрдости в соответствии Международной классификацией определены соответствующие типы снега и получены зависимости коэффициента теплопроводности снега от его плотности
ЛЕДОВЫЙ РЕЖИМ ОЗЁР ЗАБАЙКАЛЬЯ В УСЛОВИЯХ СОВРЕМЕННОГО ПОТЕПЛЕНИЯ
Get PDFThe problem of the climate change impact on the ice regime of lakes has become topical in view of the revealed (observed) shortening of the freeze-up duration and a decrease in the ice thickness for many years. The relationship between timing and duration of the ice events and climate characteristics had been found. The influence of climate change on the ice regime in the Transbaikalia was previously estimated by the example of the Ivano-Arakhley lakes. In this work we determined the trends of changes of the following parameters: air temperature, the duration of freeze-up and the maximal ice thickness as well as the reliability of these trends on lakes Arakhley, Shakshinsky, Bolshoy Leprindo, Gusinoye, Baunt, Sosnovoye. The least-squares method was used to determine the long-term trends; consistency of the changes in the studied characteristics was evaluated by means of the correlation analysis. The significance of the trends and correlation coefficients was evaluated using Student's t-statistics.Оценено влияние изменений климата на ледовый режим озёр Забайкалья с 1975 по2012 г. Современная тенденция повышения температуры воздуха влияет на даты начала и окончания ледостава, формирование максимальной толщины льда и его прирост. Продолжительность ледостава и максимальная толщина льда за многолетний период уменьшились
Развитие подвижки в западной части ледникового купола Вавилова на Северной Земле в 1963–2017 гг.
Get PDFThe glaciers and ice caps in the Arctic are experiencing noticeable changes which are manifested, in particular, in the intensification of their dynamic instability. In this paper we present data on a largescale surge in the Western basin of the Vavilov ice dome on the archipelago Severnaya Zemlya, derived from satellite images and supplemented by airborne RES-2014 and available publications. Analysis of 28 space images of 1963–2017 demonstrated that the surge developed over the whole period. In the fi st decade (1963–1973), the advance was very slow – from 2–5 to 12 m/year. Since the 1980-ies, the ice movement began to accelerate from tens to a hundred of meters per a year in the 2000-ies. The sudden change happened in the year 2012 when the surge front began to move already at speeds of about 0.5 km/year. In 2015, the volume of advanced part reached almost 4 km3. Maximal speed 9.2 km/year was recorded in 2016. From 1963 to 2017, the edge of the glacier advanced by 11.7 km, and its area increased by 134.1 km2 (by 47% relative to the basin area of 1963), that caused spreading of crevasse zone up the glacier. Surface speeds reached a maximum of 25.4 m/day in 2016 and decreased to 7.6 m/day in 2017. The authors suggest that the initial activation of the southern and western edges of the ice dome could be a reaction to the climate signal, possibly occurred several centuries ago. The ice crevassing and cryo-hydrological warming of ice, enhanced by positive feedback, resulted in instability of the glacier and the displacement of the edge of the ice belt containing moraine and frozen to the bed, which transformed into a catastrophic movement. The surge was facilitated by change of bedrock conditions as the ice lobe progressed offshore from permafrost coastal zone to the area of loose marine bottom sediments with low shear strength. The surge seems to be also stimulated by anomalously warm summer of 2012.Исследованы скорости продвижения фронта и роста площади западного сектора ледникового купола Вавилова на Северной Земле с 1963 по 2017 г. Показано, как медленное продвижение фронта перешло в фазу катастрофической подвижки, которая достигла кульминации в 2016 г., когда скорости движения ледника достигали 9,2 км/год. В результате подвижки в акваторию Карского моря на расстояние 11,7 км выдвинулась ледниковая лопасть площадью 134,1 км2 и объёмом не менее 4 км3, начавшая продуцировать айсберги