Ice and Snow (E-Journal) / Лёд и Снег
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Аномальный рельеф дна малого озера в оазисе Ларсерманн (Восточная Антарктида)
Get PDFResults of studying the bottom relief of a unique small reservoir (lake) located in the south of the Broknes peninsula, the oasis of the Larsemann Hills (East Antarctica) are presented. The first reliable depth measurements carried out in January 2022 demonstrated that within the shallow basin of the lake (average depth of 1 m or less) there are four narrow depressions (canyons) with a width of 5.5 m or less and a depth reaching 27.7m. Such a character of bottom relief has not been found before in any of the more than 150 known lakes of this oasis. To study this phenomenon, we performed fieldwork including hydrological observations, measurements of water temperature and mineralization at different horizons, high-precision bathymetric survey, and the underwater photography together with geological and geophysical investigations of the lake bank slope. A working hypothesis explaining the origin of such unusual bottom relief suggests a version of frost cracking that propagates along the fracture zone in the bedrock followed by the formation of cryoeluvium and the removal fine-grained particles (suffusion).В результате полевых работ 2021/22 г. в оазисе Холмы Ларсеманн (Восточная Антарктида) описан малый водоём с уникальными для данного региона морфометрическими характеристиками. При размерах 143 × 53 м и средней глубине большей части котловины около 1 м в его котловине развиты четыре узких впадины, ширина которых не превышает 5,5 м, а глубина достигает 27,7 м. Приведены результаты гидрологических работ на этом озере, геолого-геофизического обследования его котловины, а также предварительная гипотеза о механизме его формирования
Конвекция воздуха в снежном покрове морского льда
No full textПостроено решение задачи устойчивости воздуха в снежном покрове морского льда. Рассмотрены различные варианты динамических и тепловых граничных условий, проведено параметрическое исследование задачи. Проведено сравнение данных моделирования с результатами расчётов для реальных ледовых и метеорологических условий
Абсолютный и относительный возраст морен стадий Актру и Историческая ледников Центрального Алтая по данным лихенометрии и дендрохронологии
Get PDFDendrochronology, and lichenometry were used to determine the relative and absolute age of the Late Holocene moraines of the glaciers of the Aktru, Maashei and Shavla valleys (North Chuya ridge, Central Altai). An array of 86dendrochronological dates, related to moraine deposits, is analyzed, 30 of which are published for the first time. Also, for the first time, data on the relative (lichenometric) age of the young deposits of the Aktru Valley, and data on the lichenometry of the moraines of the Maashey glacier and one of the glaciers of the Shavly valley were obtained. We used the capabilities of each method and the expediency of their combined use in the study area. It was confirmed that the growth rates of lichens on the moraines of the Aktru stage (XVIII–XIX centuries) are generally consistent with the previously published estimates. The moraines of the Historical stage, which date earlier than 1700–2300 years ago, supports the lichens as large as 120–160 mm, but the scattering of their diameters is too large and the assessment of the lichenometric ages of these moraines seems to be problematic, but not completely excluded. The Akkem stage of glacier advance according to the recent publications dates back to the Late Glacial or Early Holocene time; the lichenometry is obviously not applicably at such ancient surfaces. According to dendrochronological dating, the glaciers of the North Chuisky Ridge in the last millennium advanced at least twice up to their maximum extent in the XVII– early XIX and XII centuries. In the 8th century, the sizes of the glaciers possibly, approached modern ones. Aſter the XVII century, the cedar (Pinus Sibirica) in Central Altai significantly reduced its distribution area due to the climate cooling, retreating from the periglacial territories, where it was distributed earlier. All trees that grew near the glaciers, above 2300 m, died. The comparison of the dates of glacier advances in the past millennia with the tree-ring, ice-core, and palynological reconstructions of summer temperature and precipitation show a good correspondence.Методы дендрохронологии и лихенометрии применены для определения относительного и абсолютного возраста позднеголоценовых морен ледников Центрального Алтая (Северо-Чуйский хребет). Установлено, что скорости роста лишайников– индикаторов на моренах стадии Актру– в целом согласуются с опубликованными ранее оценками. По данным дендрохронологического датирования, ледники этого района в последнем тысячелетии имели два максимума наступания: в XII в. и в XVII– начале XIX вв. (максимум продвижения). В VIII в. площадь ледников приближалась к современной. Размеры лишайников подрода Rizocarpon на моренах стадии Актру варьируют от 20 до 41 мм, на моренах Исторической стадии– от 120 до 160 мм, что в спорных случаях позволяет однозначно идентифицировать морену
Особенности уровенного режима приледниковых моренно-подпрудных озёр в стадии роста (на примере озёр горного массива Таван-Богдо-Ола, Юго-Восточный Алтай)
Get PDFAssessment of the dynamics of high-altitude glacial lakes is becoming increasingly important in the context of modern climate instability. The formation of new periglacial lakes and the growth of existing lakes as a result of the reduction of glaciers are recorded almost all over the world, including Russia. A rapid increase of a periglacial lake size may lead to the formation of an outburst flood. In this context, in order to prevent outburst floods, it is necessary to investigate outburst hazard lakes at all stages of their development. The periglacial lakes of the Altai mountains have been little-studied in comparison with other mountainous areas. At the same time, they are also characterized by the formation of new lakes during the period of climate nonstationarity. It was confirmed by the identified statistically significant trends in average monthly air temperatures during the ablation period. Based on the analysis of multi-temporal satellite images, it was found that the number of new periglacial lakes in the high-altitude territories of the Altai Republic (Katunsky ridge, North-Chuya ridge, South-Chuya ridge and the Tavan-Bogdo-Ola mountain massif) is increasing exponentially. For a more detailed survey and field hydrological studies, the authors chose the recently formed periglacial Lake Barsovo and periglacial Lake Gachi-Kol. Both lakes located within the northen slope of the Tavan-Bogdo-Ola mountain massif. Field observations, which were carried out in July-August 2021, have shown that both lakes are currently at the transgressive stage of development (growth stage). The transgressive phase of the lakes development is characterized by a rapid increase in size by the end of the warm period and a complex level regime on both diurnal and annual scales, due to the fact that both lakes are adjacent to the glacier.На основе анализа изменчивости гидролого-морфометрических характеристик озёр с применением спутниковых изображений и данных полевых гидрологических наблюдений, выполненных авторами в июле – августе 2021 г., описаны особенности гидрологического режима двух приледниковых озёр с трансгрессивной фазой развития, расположенных на территории горного массива Таван-Богдо-Ола (Республика Алтай)
Глобальные гляциологические модели: новый этап в развитии методов прогнозирования эволюции ледников. Часть 2. Постановка экспериментов и практические приложения
Get PDFGlobal glacier models provide a new way for studying glaciers on the regional and global scales. They make it possible to perform predictive experiments - for example, to forecast changes in glaciation and river runoff, and diagnostic ones – to identify regularities in the behavior of glaciers (a response time to climate change) taking account of their characteristics. The characteristics and design of global glacier models were described in the first part of the review (see Postnikova T.N., Rybak O.O. Global glaciological models: a new stage in the development of methods for predicting glacier evolution. Part 1. General approach and model architecture. Led i Sneg. Ice and Snow. 2021, 61 (4): 620–636. [In Russian]. doi: 10.31857/S2076673421040111.). In the second part, we present the methods for setting up of numerical experiments with these models, including model initialization, climate forcing, calibration, and validation procedures. The only way to provide the climate forcing of a glaciological model on a regional or global scale is to use low-resolution reanalysis or output of climate modeling on GCMs or RCMs that needs to use a process of scaling to reproduce the local climate in a complex topography where glaciers are usually located. Calibration of mass balance complements the downscaling of climate forcing for each glacier, and usually it includes parameters responsible for the glacier's response to climate change. Sampling from the Latin hypercube and Bayesian inversion are some of the methods discussed in this connection. In this review we present a comparative description of the selected global glaciological models, the results obtained by both diagnostic and prognostic ones, as well as scale and significance of them. We discuss also ways for further development of global glacier models, in particular the inclusion of 3D-modeling and the moraine (debris cover) block. The difficulties arising in a process of modeling glaciation of a particular mountain region or several regions are noted.Глобальные гляциологические модели открыли новые возможности для исследования ледников на региональном и глобальном уровнях. Они позволяют проводить как прогностические эксперименты, например, предсказывать изменение оледенения и стока рек, так и диагностические – выявлять закономерности поведения ледников (например, время реакции на изменение климата) в зависимости от их характеристик. Архитектура глобальных гляциологических моделей описана в первой части обзора. Во второй части представлены методы постановки численных экспериментов на этих моделях, их сравнительная характеристика, основные полученные результаты, их масштаб и значимость. Обозначены направления развития глобальных гляциологических моделей и сложности, которые возникают при моделировании оледенения в региональном и глобальном масштабах
Баланс массы ледников Корякского нагорья Нежданный и Соседний за 1961–2016 гг.
Get PDFThe Koryak Highland is one of the areas of the present-day mountain glaciation in the north-east of the Asian part of Russia. Its remoteness and inaccessibility are serious obstacles to the ground-based (field) researches, so our knowledge of the regime of glaciers in this area is still incomplete. Objective of this study was to obtain data on changes in the state of glaciers for about a half-century period. For this purpose, the following information was used: results of ground-based phototheodolite surveys of two glaciers on the Ledyanaya Mountain massif (2,453 m) in the central part of the highland, carried out in August 1961 by the expedition of the Institute of Geography of the USSR Academy of Sciences, data from recent space surveys SPOT 6, and a digital relief model ArcticDEM v3.0 2016. The glaciers under investigation are Nezhdanny and Sosedniy. Using these data, the mass balance of glaciers was estimated by the geodetic method. It was found that for 55 years, the area of glaciers decreased by 0.75 km2 (15.2%), the volume – by 71.74 ± 16.51 million m3, and the average lowering in height of the surface – 16.7 m. For the period 1961–2016 the average annual specific mass balance of glaciers was equal to –0.362 ± 0.065 m w.e. yr−1. In this region the main factors exerting influence upon changes in the size of glaciers are the following: first, the summer air temperature rise of about 2 °C since the end of the twentieth century, and the second, a decrease in the amount of solid precipitation by 0.15 m w.e. per year. Degradation of glaciers is caused by changes in conditions of glacial alimentation, increased ablation, and the active cryogenic factors. At the same time, a new rock glacier is being formed in the alimentation area. It is possible that in the future the new one will replace the degrading glacier.Оценены изменения объёма двух ледников в центральной части Корякского нагорья за период 1961–2016 гг. с использованием исторического топоплана масштаба 1:5000 и данных современных космических съёмок высокого разрешения. Площадь этих ледников сократилась на 15,2% (0,75 км2), объём – на 71,74±16,51 млн м3. Их поверхность понизилась в среднем на 16,7 м, а средний удельный баланс массы составил –0,362±0,065 м в.э. в год. На фоне деградации ледника развивается процесс его преобразования в каменный глетчер
Современное оледенение Шапшальского центра оледенения (Восточный Алтай) и его динамика в период с максимума малого ледникового периода.
No full textПолучены новые карты и каталоги ледников малоисследованного Шапшальского центра оледенения на Восточном Алтае. Реконструированы ледники данной территории в максимум малого ледникового периода, анализирован характер их последующего сокращения. Более детально рассмотрено сокращение крупнейшего ледника Шапшальского хребта по пяти временным срезам. Проведены расчеты индекса баланса массы ледника и времени его климатического отклика
Распространение пещер с многолетним льдом на Южном Урале и в Предуралье
Get PDFThe paper presents systematized information about distribution of karst caves containing accumulations of old ice and snow outside the zone of continuous permafrost. It was found that among total number of 1,150 caves in the region known by January 1, 2022, the old ice had been registered only in 68 (6%) ones. Distribution of them is conditioned by the general mechanisms of development of karst cavities, but a number of additional conditions are required to form the snow-ice accumulations within them. Ice and snow are formed mainly in bag-shaped caves confined to the middle and upper parts of river valleys, or in caves located in the upper reaches of the ravines on the watershed areas, the entrances to which are represented by wells, deep karst channels or are located in sinkholes. The intensity of accumulation and conservation of snow and ice in caves, under other favorable morphological and hydrogeological conditions, is directly dependent on the area of the entrance to the cave and the slope of the floor at its entrance. Snow-ice accumulations are represented by ice bodies, stalactites and stalagmites, hoarfrost and large ice crystals, snow, firn and ice. The most developed of them is ice. The maximum recorded area of the cave ice is 5000 m2, its thickness is 11 m, the depth of penetration of glaciation deep into the karst massif from the entrance reaches 70 m, and the length is 250 m. Factors that reduce the accumulation of snow and ice in the caves of the region include: periodic flooding of karst cavities, shortening of woody vegetation on the surface above them, and cave attendance. On the case of the Askynskaya cave, the dependence of the state of snow-ice accumulations on local climatic conditions and the degree of anthropogenic load has been determined. It is recommended to monitor the state of snow and ice formations in the rarely visited Ledyanaya-Lipovaya cave with the most thick icing, in order to establish a correlation between the state of glaciation of the cave and changes in local climatic conditions.Систематизированы сведения о распространении карстовых пещер с многолетними снежноледяными образованиями. Установлено, что из всех известных пещер региона только в 6% зафиксированы многолетние лёд и снег. Распространение таких пещер обусловлено общими закономерностями развития и распространения карстовых полостей. Однако для формирования в них снежно-ледяных образований требуется ряд дополнительных условий
О формировании новых приледниковых озёр в бассейне залива Грёнфьорд (Шпицберген) в 1938–2010 гг.
Get PDFBased on remote sensing and field methods, the state of the glacial lakes located in the Grønfjord Bay basin, Svalbard, was assessed for 2008–2010. New lakes were formed due to the retreat of the mountain-valley glaciers of the Nordenskiöld Land and the formation of moraine-ridge topography. According to the 2008–2010 aerial survey data, 111 glacial lakes were identified in the basin area. Most of the new lakes were formed on the moraines of the large mountain-valley glaciers Vestre and Austre Grønfjordbreen, Brydebreen, Skavlefjellbreen, and Tungebreen. The total area of the glacial lakes is 2.047±0.001 km², 84% of their total area belongs to the two largest lakes Bretjørna and Stemmevatnet. The rest of the lakes in the territory are small, from 20 to 330 m in length, and shallow. The estimation of the volume of water in the lakes was based on field measurements of the depths of 26 lakes and the correlation found. The total volume of water is 24.1 million m³, which is comparable with the value of annual glacial runoff in the basin.С помощью картографического сервиса Норвежского полярного института (toposvalbard) получены данные об озёрах в бассейне залива Грёнфьорд. Всего на водосборе на 2008–2010 гг. обнаружено 134 озера, среди них 111 – новые приледниковые озёра, которые образовались в связи с сокращением ледников с начала ХХ в. Подавляющее большинство приледниковых озёр появилось на территории морен крупных горно-долинных ледников – Западный и Восточный Грёнфьорд, Тунге и Скавле. Оценены суммарная площадь, объём озёр на водосборе и плотность распределения приледниковых озёр на площади морен. С 1938 до 2010 г. суммарная площадь всех озёр увеличилась в 4 раза
Пространственная и временная изменчивость снежного покрова в южной лесостепи Верхней Оби
Get PDFThe study area is the forest-steppe in the Upper Ob basin located on the south of the West Siberian Plain. The results of studies of the dates of setting-up and loss of a stable snow cover and its duration are presented, the thickness of snow and snow storages for the period of maximum snow accumulation are analyzed. We used observational data obtained on routes and meteorological sites in 1966–2018 together with our own snow measurements of 2011–2019. It was found that in the southern forest-steppe, the duration of the stable snow cover presence decreases mainly as a result of its earlier destruction. At the same time, on the routes in a «field» the thickness of snow and snow storage increase due to growth of winter precipitation. But no such trend is observed on the routes in a «forest» which is explained by influence of its canopy density. The snow cover here is unevenly distributed over the territory because the driſted snow transport depends mainly on features of the vegetation cover and the terrain relief. The route snow surveys performed near weather stations do not reflect the entire landscape diversity of the territory.Проанализированы особенности сезонного снегонакопления за многолетний период. Установлены тенденции изменений характеристик снежного покрова с середины 1960-х годов и его пространственное распределение в зависимости от ландшафтов в пределах южной лесостепи Верхней Оби. Использованы данные государственных гидрометеостанций и собственных снегомерных работ 2011–2019 гг