Ice and Snow (E-Journal) / Лёд и Снег
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Протяжённость крупных разрывов в дрейфующем льду приатлантической части Арктического бассейна по данным снимков ИСЗ
Get PDFData on the extent of the large discontinuities of drifting ice in the Western part of the Arctic basin are ana‑ lyzed for the period from October 2005 to September 2012. The data were obtained as a result of decoding the low resolution images received from the NOAA satellites. Areas with the low, medium and high lengths of the leads were isolated. It was found that, during the entire ice cycle, areas with low lengths (less than 100 km) were the most numerous. Definite seasonal as well as inter‑annual variations were also determined in the changes of repeatability of the lead lengths in the ice cover, its relative value and the average values. They are manifested in changes of the mentioned parameters being calculated for both, the whole set of leads, and separately from data within each of the isolated areas. The seasonal variations of these parameters are shown to be consistent with the well‑known intra‑annual changes in the state of drifting ice, consisting in the development of the process of ice formation from October to March, and the subsequent destruction of the ice fields in April–June. Fluctuations with duration up to five years were revealed within the inter‑annual changes of characteristics of the lengths of leads. The presence of these inter‑annual changes may be explained by the development of the processes leading to «weakening» of drifting ice during the period under consideration. The assumption that the fluctuations in the length of discontinuities of the ice were related to the changes of the rate of the ice drift is grounded.Исследуется протяжённость крупных нарушений сплошности дрейфующего льда в западной части Арктического бассейна с октября 2005 по сентябрь 2012 г. на основе дешифрирования снимков малого разрешения с искусственных спутников Земли (NOAA). Отмечены сезонные и межгодовые вариации в изменениях повторяемости протяжённости разрывов в ледяном покрове, её относительной величины и средних значений. Наличие межгодовых колебаний объясняется развитием процессов, вызывающих «ослабление» дрейфующего льда и предположительно связанных с изменениями скорости дрейфа льда
Изменения ледника Абрамова (Алайский хребет) c 1850 по 2014 г.
Get PDFThe purpose of this study was to determine the nature and rate of changes of the Abramov glacier over the period from 1850 to 2014. The glacier is located on the Alay Ridge in Kyrgyzstan. Its borders were estimated by means of interpretation and analysis of space images from the satellites Landsat-2, 5, 7, 8, KH-4А and KH-9 (program Corona), Geoеye-1 together with aerial photographs and topographical maps, and with addition of results of the field survey of the glacier’s tongue by GPS instruments. As a result, we could find that the longstanding degradation of the glacier continued over the whole period under investigation, and against the background of that there were periods of relative stabilization of the front of the tongue as well as the periods of the glacier advances of different duration and intensity. In 1850, the total area of the glacier accounted for 26.4 km2, but by 2014 it reduced by 3.65 km2, or 13.8%, and became equal to 22.75 km2. Thus, annual reduction of the glacier area was equal approximately to 0.02 km2 per a year, and its length decreased by almost 2950 m, i.e., the glacier contracted, on the average, by 18 m per a year. It should be noted that changes of the glacier area were similar during both the initial and final periods of observations, and it means that no intensification of anthropogenic impact upon the glacier was observed. Obviously, this fact is indicative of the prevalence of natural factors in the change of the glacier, expressed in irregular duration of cyclic changes.Цель данного исследования – определить характер и скорость изменения ледника Абрамова. Методика определения границ ледника за 1850–2014 г. предусматривала дешифрирование и анализ космических снимков спутников Landsat-2, 5, 7, 8, KH-4А, KH-9 программы Corona, Geoеye-1, аэрофотоснимков и топографических карт, а также съёмку в полевых условиях границ языка ледника с помощью GPS-приборов. В эти годы продолжалась деградации ледника Абрамова, его площадь сократилась на 3,65 км2, т.е. на 13,8%. Средняя скоростью сокращения площади ледника составила около 0,02 км2/год
Применение метода электротомографии для изучения внутреннего строения каменных глетчеров Алтая
Get PDFInternal structure of rock glaciers was investigated at two key sites in Altai by means of electric tomography. It had been found that the rock glaciers of the same type, located at different altitude levels, differ in electric resistances of ice nuclei and the degree of consolidation of the ice material inside of them. Typical characteristics of the ice core of a rock glacier in the high-mountain area are the following: electrical resistivity is about 1000–2000 kOhm∙m and a high degree of the ice consolidation, while the same for the mid-mountain region: the electrical resistivity is 150–300 kOhm∙m and the presence of the talik zones within the glacier body. Using the method of electric tomography for investigation of the internal structure of the rock-glaciers makes possible to reveal presence of frozen soils and ice and to find the upper boundary of occurrence of them from anomalously high specific electric resistance. However, it is not always possible to determine a thickness of the rock-ice formation, and to estimate a degree of its consolidation that does not allow calculating the ice content volume. Limitations of this technology can be overcome by the use of electric tomography in combination with other geophysical methods.На двух ключевых участках территории Алтая выполнено исследование внутреннего строения каменных глетчеров с использованием метода электротомографии. Установлено, что каменные глетчеры, располагающиеся на различных высотных уровнях, отличаются по удельному электрическому сопротивлению и степени консолидации ледяного материала. Для каменно-ледяного ядра каменного глетчера в высокогорье характерны удельное электрическое сопротивление 1000– 2000 кОм∙м и высокая степень консолидации льда, а для каменного глетчера в среднегорье эта величина равна 150–300 кОм∙м, а в теле каменного глетчера присутствуют таликовые зоны
Инвентаризация ледников Восточного Саяна по материалам космических съёмок
Get PDFSmall glaciers (areas smaller 1 km2) are the most numerous in most mountainous and glacial regions of the Earth, but their responses to the present‑day climate change are still to be investigated. The paper presents results of the new inventory of small inter‑continental glaciers located in the Eastern Sayan (South of Eastern Siberia). The previous (1950) glacier inventory was made from data of aerial photography carried out in the middle of the 20th century (USSR Glacier Inventory, КЛ 1950). A more complete inventory of the East Sayan glaciers for the state of 2000 (КЛ 2000) had been performed using the multichannel space images (Landsat Enhanced The‑ matic Mapper (ETM+) of 2000 and 2001, and the Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM). In addition, some glaciers from the Inventory KL 1950 were re‑mapped on the basis of the Land‑ sat images (TM, ETM+, 1986‑2011) for years 1950, 1990 and 2010. The glacier outlines, determined on the test site from images of medium (Landsat) and high (World View‑1) satellite resolution, were compared that con‑ firmed that errors of mapping of small glaciers did not exceed 15%. The KL 2000 contains data on 172 glaciers with a total area of 16.6±1.9 km2. Glacier sizes are from 0.02 to 1.37 km2. For 1950–2000, the total area of the East Sayan glaciers had decreased by 59% (0.40% per a year). In 1990–2000, the glaciers decreased the most rapidly (by an order of magnitude faster as compared to the period of 1950–1990.). In 2000–2010, the area of glaciation slightly increased (by 4%) owing to formation of very small glaciers (area smaller 0.5 km2). On the whole, changes in glacier areas in the years 1950–2010 are in the good agreement with changes in amounts of winter precipita‑ tion and summer temperatures. In addition to regional climatic factors, there are also some local factors related to the topography and microclimate of individual glaciers which do also influence on the dynamics of small glaciers.С использованием космических снимков Landsat и цифровой модели SRTM составлен новый ГИС-каталог ледников Восточного Саяна по состоянию на 2000 г.; выполнен статистический анализ морфометрических характеристик ледников. По отдельным выборкам ледников реконструированы их контуры на конец малого ледникового периода (~1850 г.), а также на ~1990 и ~2010 гг. Проанализированы изменения площади ледников за период 1850–2010 гг. и оценена роль температуры воздуха и осадков в динамике оледенения
Межгодовая изменчивость и прогноз весенних ледовых явлений на оз. Байкал и водохранилищах Ангарского каскада
Get PDFThe study of interannual variability of ice phenomena on large inland waters, as well as the ice forecasts for them are of great practical importance for navigation because any ice on water interferes with navigation. This article presents a description of the developed approach to mapping the stages of melting and destruction of ice cover on Lake Baikal, and the Bratsk and Ust-Ilimsk reservoirs using data from AVHRR (Advanced Very High Resolution Radiometer) and shows examples of the ice condition maps in the spring. The AVHRR data, obtained for the period 1998–2015, made possible to analyze processes of the ice disappearance on aquatories of the South, Central and North parts of Lake Baikal, and the Bratsk and Ust'-Ilimsk reservoirs including determination of dates of the total ice disappearance (the first ice-free dates) on the reservoirs under investigation: the average, earliest and latest dates, and a range. It has been found that the interannual changes of these dates are the opposite to the inter-annual fluctuations of values of the Arctic Oscillation (AO) index, that allows using the AO index as a predictor in regional predictive dependencies.Using results of analysis of the AO index values, averaged over different time intervals, and the data series of the first dates of the ice-free situations we constructed regional equations allowing to foresee a character of the ice situation with the average earliness from 21 to 33 days. Tests of effectiveness of the proposed predictive dependencies demonstrated a good quality of forecasts of the dates when Southern, Central and Northern parts of Lake Baikal,as well the Bratsk and Ust-Ilimsk reservoirs become totally free of ice.По данным радиометра AVHRR изучена изменчивость сроков очищения ото льда акваторий озера Байкал, Братского и Усть-Илимского водохранилищ с 1998 по 2015 г. Разработаны региональные методики долгосрочного прогнозирования сроков полного очищения исследуемых акваторий с использованием значений индекса Арктической осцилляции, позволяющие прогнозировать характер развития ледовых явлений со средней заблаговременностью от 21 до 33 суток
Пайкерит – льдокомпозит Второй мировой войны
Get PDFDuring the war, government of the allies considered the construction of ice structures converted from artificial icebergs into aircraft carriers. The idea to use ice for construction of floating aerodromes, or giant aircraft carriers, was launched by Geoffrey Pyke, and then was developed in a project called «Habbakuk». Aircraft carriers, made of ice, had to work for a long period of time at temperatures of water and air, resulting in rapid destruction of the structure of ordinary ice. The ice in its pure form is unsuitable for any engineering form therefore the experiments on reinforcement of ice were undertaken. New form of ice engineering was based on the type of reinforcement patterns of ice and coating it with an insulating material, which would greatly reduce the influence of melting due to the temperature of the ambient air. After tests with different substances and proportions, it was found that the mixture of ice with wood pulp, amounting to about 14%, gives the best result of reinforcement. Proposed dimensions of «Habbakuk» were 610 m (2000 ft) long, 90 m (300 feet) in width and a height of 60 m (200 ft). In 1943, on the surface of the lake Patricia a reduced model to test the viability of the project was constructed. Development of improved long-range aviation, the airbase in Iceland and other technological advances contributed to the successful elimination of the threat from submarines, so the project had been suspended. The technology of strong ice structures invented during the World War II time can still have practical applications today.Приведён исторический опыт по созданию авианосца из композиционного материала – сверхпрочного льда, представляющего собой замороженную смесь хлопковой ваты или целлюлозы с водой. Указаны причины, по которым чистый лёд не пригоден для ледового инжиниринга. Рассмотрены физико-механические свойства льдокомпозитного материала пайкерита, проблемы при его создании и использовании, а также размеры предполагаемого авианосца. Даны выводы относительно идеи осуществления оригинального проекта и возможности современного использования пайкерита в районах Крайнего Севера и приравненных к ним местностях
Девдоракский ледник, Казбек: к истории исследований природных катастроф в XIX и начале XXI в.
Get PDFThe Devdorak Glacier located on the Eastern slope of Mt. Kazbek is known since the end of the 19th century for its catastrophic ice discharges into the river Terek canyon. The so-called «Kazbek blockages» stopped the river flow, thus leading to formation of a dammed lake. The lake was then broken through by the heavy floods. Evidences of such events are available for 1776, 1785, 1808, 1817, and 1832. Later on, the glacier surges did sometimes occur, but they never reached the river. The blockages interrupted the traffic on the Georgian Military Highway – the basic way across the main ridge of the Caucasus, for long time periods. Investigations of the Devdorak and other Mt. Kazbek glaciers were organized in 1862 and lasted until the end of 19th century. But the scientists could not reach a common consensus in resolving the main issues, i.e. the causes of the «blockages» and possibilities of their soon repetitions. Different hypotheses explaining the ice discharges by either morphology of the glacier and the river valley or by earthquakes were proposed. Some authors insisted on a probability of occurrence of new «blockages». But the mostly widespread opinion was that since all the Kazbek glaciers were in the state of degradation any risk of new «blockages» was absent while this tendency remained. Since the previous disasters, the Devdorak Glacier posed no threat for about two centuries. However in May 2014, a huge downfall of rock and ice suddenly came down on the glacier in its upper zone. As a result a large mass of rock, stones, and mud blocked the Terek river bed again. This event was not related to regime of the glacier itself. Most likely it was a new manifestation of the Mt. Kazbek volcanic activity.Первые систематические наблюдения за ледниками Кавказа связаны с изучением катастрофических выбросов льда в ущелье р. Терек в результате периодических подвижек Девдоракского ледника в конце XVIII – начале XIX вв. Анализ причин «казбекских завалов» не привёл учёных того времени к единому мнению. Тогда ещё не существовало понятия о классе пульсирующих ледников. Двумя столетиями позже – в мае 2014 г. – снова случился неожиданный обвал льда и горной породы в фирновой области Девдоракского ледника. Это событие имело другую природу и, вероятно, связано с новейшими проявлениями вулканической активности в недрах Казбека
Два подхода к расчёту расчленения гидрографа стока реки с ледниковым питанием с помощью изотопных методов
Get PDFApplication of the stable isotope method in the balance equations used to calculate separation of the runoff hydrograph from the Djankuat Glacier basin is demonstrated. Simultaneous solution of equations of water, isotope and ion balances is applied to estimate contributions of different components and processes to formation of the Djankuat River runoff regime. For June 2014, we made calculations for the purpose to separate contributions of the spring (isotopically weighted) snow and winter (isotopically depleted) snow. Field works in the glacial basin Djankuat were performed during two ablation seasons, i.e. from June to September of 2013 and 2014. Two approaches were used when calculating separation of the runoff hydrograph by means of solution of systems of equations for isotopic and ion balances: 1) taking account of the isotope fractionation during snow melting, and 2) with no account for the fractionation. Separation of the hydrograph for June 2014 have shown that about 15–20% of the Djankuat River runoff is formed by spring snow melting, sometimes increasing up to 36%. Contribution of spring meltwater to the total runoff increases when the isotope fractionation during the snow melting is taken into account for the calculations. In this case, the contribution of spring snow changes from 30 to 50%.Рассмотрено применение метода стабильных изотопов в балансовых расчётах расчленения гидрографа стока с ледника Джанкуат. Изученные изотопные вариации стока на замыкающем створе р. Джанкуат для двух сезонов абляции 2013 и 2014 г. совместно с измерениями δ18О и минерализации различных источников питания р. Джанкуат (атмосферные осадки, снег разных сезонов, фирн, лёд и грунтовые воды) позволили расчленить гидрограф стока 2014 г. Применялись два методических подхода к расчётам: разделение гидрографа стока решением систем уравнений ионного и изотопного баланса с учётом изотопного фракционирования при таянии снега и без учёта фракционирования. Установлена величина погрешности расчётов с использованием значений δ18О и абсолютных концентраций 18О
Изотопно-кислородный состав льда ледника № 30 в горах Сунтар-Хаята
Get PDFThe object of research is the mountain-valley glacier № 30, located in the central part of the Suntar-Khayatа Ridge – one of the largest centers of modern glaciation of the North-East of Russia. This glacier had been chosen due to lamination of ice on its surface, providing successive sampling of increasingly young ice upward the glacier slope. At the end of August 2013, surface ice of the glacier was sampled within the altitude range 2060–2510, an age of this ice here was estimated to be about 500 years old. Variations of δ18О values in the glacier ice amounted about 5.5‰: from −20.2 to −25.9‰ that is numerically consistent with isotopic values for the neighboring glaciers № 29 and 31. No essential relation between the ice isotopic composition and altitude, age or the change of the ice granularity was found. Absence of high-altitude isotope effect is explained by the fact that preciptation on the glacier № 30 falls at the same level of condensation as well as by intensive infiltration-congelation ice formation and fixation in the firn and snow cover of a part of the meltwater coming from higher and steeper areas on gently sloping sites of the glacier. The δ18О values of ice from glacier № 30 are rather «heavy» for glaciers being formed in severe climate conditions with average January temperature of −28 °C. According to Dansgaard's dependence δ18Оprecipitation – t °Cair the winter snow on the glacier № 30 should be hypothetically characterized by the δ18О values from −30 to −40‰ which are typical ones for the winter snow in Siberia. Oxygen isotope values of the ice show insignificant contribution of winter snow into formation of the glacier and prevalence of spring-autumn snowfalls. No definite trend of changes in the glacier alimentation and the ice-formation process was found for the last 500 years.Рассмотрен изотопно-кислородный состав поверхностного льда ледника № 30 в горах Сунтар- Хаята, отобранного в 2013 г. Вариации δ18О во льду ледника № 30 составили около 5,5‰. При этом не отмечено существенного изменения изотопного состава льда с высотой или с его возрастом. Сопоставлен изотопный состав льда ледника № 30 и зимнего снега, выпадающего в разных районах Сибири. На основании полученных изотопных данных показано, что питание ледника происходит преимущественно за счёт весенне-осенних осадков при незначительном участии зимнего снега
История оледенения Арктического бассейна: взгляд из прошлого для оценки возможных изменений в будущем
Get PDFThe process of the sea ice formation in the Arctic Ocean is analyzed for the period of the last 65 million years, i.e. from the Paleocene to the present time. Appearance of sea ice in the high latitudes is demonstrated to be caused by the negative trend in global temperatures due to decreasing of the CO2 concentration in the ancient atmosphere. Formation of seasonal and perennial ice cover in the limited area near the Pole could take place during the mid-Neogene period, about 12–13 Ma ago. However, areas of the sea icing could be obviously changed for this time during periods of the climate warming and cooling. Permanent sea ice had been formed in the early Pleistocene, i.e. about 2.0–1.8 Ma ago only. Paleoclimatic reconstructions, based on the indirect data and modeling simulation for the Holocene optimum (10–6 ka ago) and for the Last Interglacial period (the isotopic substage in the marine cross-section 5e, about 125–127 ka ago) had shown that rising of global temperatures by 1.0–1.5 °C resulted in strong decreasing of the sea ice area, and the perennial ice cover became the seasonal one. Relatively small changes in the incoming solar radiation originating during the spring-summer time due to the orbital factors played the role of a trigger for onset of the melting process. Further on, the process could be enhanced owing to difference in the albedo between the ice cover and open water. Recently, the rapid shortening of the sea ice area is noted, and in some parts of the Arctic Ocean the area is twice cut down as compared with the normal. In 2015, the record low area of the winter sea ice was observed, and therewith the maximum of the ice area shifted to the earlier period (by 15 days) as compared with the period of 1981–2010. The winter fluctuations of the sea ice areas are as much important as the summer ones, since they are the best indicators of the present-day global warming. Thus, it can be supposed that some mechanism of replacing the perennial sea ice by the seasonal ones has been started up, that is the natural process of transition from seasonal ices to the next stage that is the ice-free Arctic. On the assumption that increasing of the CO2 concentration will continue despite the efforts to reduce emissions of greenhouse gases into the atmosphere, and the radiation forcing will approach to doubling of the CO2 content, one of the scenarios of the past can be realized now.Быстрое сокращение площади морских льдов в Арктике в последние десятилетия обусловлено их реакцией на повышение глобальной температуры. Морские льды – прекрасный индикатор состояния глобальной климатической системы как в историческое время, так и в отдалённом прошлом. Анализ исторических данных показывает, что современное сокращение площади и толщины морских льдов в Арктике беспрецедентно за последние 1450 лет. На основе синтеза морских, континентальных и других косвенных данных рассматривается история образования морского оледенения Арктики за последние 65 млн лет, от раннего палеогена до голоцена. Сокращение площади морских льдов в Арктике, уменьшение их толщины и увеличение площади одногодичного льда свидетельствуют, что запущен механизм замещения многолетних льдов сезонными. Это – естественное состояние перехода от сезонных льдов к следующему этапу – безлёдной Арктики