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Крупные приледниковые озёра архипелага Шпицберген: их состояние в 2008–2012 г. и динамика с 1991 по 2022 г.
Get PDFApproximately 3,790 lakes of various genesis existed in the Svalbard archipelago in 2008–2012, the total area of which reached 395 km2. Among them, periglacial lakes were new objects which had been formed since the beginning of the 20th century due to the deglaciation of the archipelago. We found 554 glacial lakes which areas exceeded 0.01 km2. The total area of these lakes amounted to about a half of the area of all the lakes in the archipelago – 185 km2, and two thirds of this value were large glacial lakes. The paper presents the spatial distribution of large periglacial lakes and variability of them caused by the climate warming in the archipelago. At present, there are 35 periglacial lakes (over 1 km2 in size); all of them are in contact with glaciers and the greater part of them are dammed by the terminal moraines or by a glacier itself. According to the cartographic data of the Norwegian Polar Institute and satellite images, the areas of large lakes were determined successively in 1991, 2002, 2012, and 2022. For the period from 1991 to 2012, there was a twofold increase in their area from 24.4 to 53.7 km2, but in 2012–2022 this process slowed down. On the east of the archipelago, where the inland ice is widespread, the process of the lake formation is much slower. It had been noted that on the west all large glacial lakes were formed after 1936 due to active retreat of the glaciers. At the same time, both on the north and east, most of the large glacial lakes existed prior to 1936. During the periods under consideration, changes in the areas of individual objects reached multiple values. The most large-scale changes in the lake areas were associated with the ablation of glacial fronts in contact with the lake, a glacier surge, and outbursts of a few dammed lakes. Six lakes were identified, where the water level drop reached tens of meters. Despite the slowdown in the formation of lakes in the last decade, the enlargement of lakes continues. Relative increase in the total area of the large periglacial lakes over the past 30 years on the west and east of the archipelago is in direct proportion to decreasing in glaciation of these regions. Thus, the process of formation of large periglacial lakes may be used as an indicator of climate change in the archipelago.По состоянию на 2008–2012 гг. на Шпицбергене существовало 35 приледниковых озёр размерами свыше 1 км2. Они составляли около 1% от общего количества всех озёр архипелага, а их суммарная площадь была равна трети площади озёрного фонда архипелага. В последние десятилетия на западе архипелага крупные озёра значительно увеличились по площади. Рассмотрена динамика крупных озёр архипелага в период с 1991 по 2022 г
Геоэлектрические модели гляциально-мерзлотных каменных образований Центрального Алтая
No full textGeophysical observations of the structure of glacial-permafrost rock formations (hereinafter referred to as GPRF), common in the Central Altai in the valleys of the Chuya, Dzhelo, Elangash and Akkol rivers, were carried out by way of electrical resistivity tomography using the multi-electrode electro-prospecting station “Skala-48”. The main objective of the research was to identify the features of the internal structure of GPRF basing on the data of electrical sounding and aerial photography. The application of the geophysical method made it possible to localize rock-ice cores within the GPRF. Analysis of the geoelectrical crosssections allowed finding that the rock-ice cores were characterized by high values of specific electrical resistance (SER) – from 10 to 100 kOhm × m and more. The depths of occurrence of rock-ice material on the geoelectrical sections varied from 2 to 10 m, on the average. Using the data of the aerial photography carried out above the studied areas, three-dimensional geoelectric models and maps of the distribution of SER were built for different depths. When analyzing the three-dimensional model of the GPRF, it is clearly noticeable that the features of the nature of the SER distribution reflects the inhomogeneous distribution of ice within the rock-ice core of the GPRF. As a result of our studies performed by the method of electrical tomography and interpretation of a three-dimensional geoelectric model, it was estimated that thicknesses of the rock-ice material varied from 7 to 32 m, thawing niches were revealed and localized, and the potential volume of the rock-ice core was determined. Thus, the above mentioned geophysical and geomorphological studies in that the features of the internal structure of GPRF in key areas have been established. For each GPRF, the thicknesses, resistivity, and depth of occurrence of rock-ice cores were determined, and the dependence of the morphological structure of the GPRF surface on internal structure of them was analyzed. A preliminary assessment of water reserves in individual GPRF had also been made.Проведено комплексное изучение гляциально-мерзлотных каменных образований на территории Центрального Алтая в долинах рек Джело, Елангаш, Аккол и Чуя с помощью электрозондирования, геодезической сьёмки и аэрофотосъёмки. Интерпретация данных электротомографии позволила установить глубину залегания и мощность каменно-ледяных ядер. Трёхмерные геоэлектрические модели ГМКО позволили проанализировать распределение льда внутри ГМКО и оценить запасы воды в них
Высота границы питания на куполе Беллинсгаузен, Антарктика
Get PDFWe present an analysis of the equilibrium line altitude (ELA) on the Bellingshausen Ice Dome on King George Island (Waterloo), Antarctica, derived only from ground-based glaciological surveys for the period 2007–2012 and 2014–2023. A good relationship was found between ELA and mean summer air temperature (XII-II months) with a coefficient of determination of about 0.8. Assuming the stability of this relation in the past, the changes in the ELA during the entire period of observations at Bellingshausen weather station (from 1968) were reconstructed. Since negative ELA values were obtained for some years, which is physically impossible, they were artificially adjusted to sea level. A good correlation of air temperature between the Bellingshausen and Deception Island weather stations allowed extending the reconstruction of ELA for a longer period (from 1947).By cleaning up the strong interannual f luctuations in ELA using five-year moving averages, two complete periods of ELA change (from minimum to minimum) were identified for approximately 20 years (1947–1968) and 45 years (1968–2013). From 2014 to present time, the third period has been continuing. At the apogee of each period, the ELA was higher than the Bellingshausen Ice Dome height, which indicates that in these years the ice dome completely lost accumulation area. For the Bellingshausen and Warsaw ice domes, a pattern of higher ELA position on the western and southern slopes compared to the eastern slopes was revealed, which is probably applicable to the entire King George Island.Since the ELA variations on King George Island are generally synchronous with its variations on Livingston Island, the reconstructed ELA on the Bellingshausen Ice Dome can probably be useful for reconstructing the glaciation history of the South Shetland Islands. Получены данные о высоте границы питания (ELA) для ледникового купола Беллинсгаузен на острове Кинг-Джордж (Ватерлоо) в Антарктике за 2007–2012 и 2014–2023 гг. Восстановлен характер изменения ELA для купола с 1947 г. по настоящее время. Выявлена синхронность изменения ELA на островах Кинг-Джордж и Ливингстон
Толщина и объём ледников массива Монгун-Тайга, Алтай, в 2021 г. по данным георадиолокации и моделирования
Get PDFThis article presents the results of estimating the scale of the present-day glaciation of the Mongun-Taiga Mountain range (Eastern Altai) based on the decoding multi-time satellite images, GPR data and modelling using GlabTop2 and the Volume-Area Scaling (VAS) method. By 2021, 38 glaciers have been identified according to the hydrological principle and 36 ones – by the morphological principle. The total area is estimated as 17.18 ± 1.13 km2. Since 2010, area of the glaciers has decreased by 15%. The thickness of the glacial complex on the main peak of the Mongun-Taiga Mountain range was measured in the ablation season of 2021. More than 6 km of profiles were obtained by the GPR survey with accuracy of about 1%. Based on these data, the GlabTop2 model was calibrated. Then the spatial distribution of the ice thickness was obtained over the entire massif. The total volume of ice in the f lat-summit glacier № 17 is estimated at 0.202 ± 0.008 km3 of ice. According to the GlabTop2 model with the morphological approach the ice volume of the whole massif was estimated at 0.733 ± 0.052 km3, and with the hydrological approach: 0.888 ± 0.061 km3. Determination of the boundaries of glaciers by the VAS method gave larger values: 0.690 ± 0.038 km3 with a morphological approach and 0.757 ± 0.036 km3 with a hydrological method. Consequently, with the same area of glaciers, volume determined by two different approaches can be rather different. This has a decisive influence on the morphological structure of ice reserves: the role of large forms of glaciation sharply prevails with the morphological approach. Most of the ice is contained in glaciers of the flat summit (27–40%). With the hydrological approach, which is used most often, the role of small forms of glaciation is overestimated. At the same time, the contribution of flat-summit glaciers is estimated at only 2%.Определены границы ледников массива Монгун-Тайга на основе гидрологического и морфологического подходов, определено сокращение площади оледенения за 2010–2021 гг. По данным георадиолокации произведена калибровка модели GlabTop2 для ледников плоской вершины. Получен диапазон значений объёма льда всего массива по модели GlabTop2, по степенным зависимостям при морфологическом и гидрологическом подходе к выделению границ ледников. Оценен вклад различных типов ледников в структуре запасов льда
Оценка статистической связи между полями экстремальных сжатий морского льда с разной пространственной детализацией
Get PDFIce pressure is characterized with significant spatial variability. Study of this variability with the help of in situ observations is rather difficult, because (1) the instrumental measurements are expensive and technically complicated, and, hence, the amount of such measurements is little, and (2) the visual observations have pre-dominantly qualitative character and depend significantly on the observer’s experience. The most widely used method of obtaining the ice pressure information is model simulations. The existing ice dynamics models allow simulating the ice pressure averaged within the area of the model grid cell, which usually has the spatial size varying from 5 to 25 km, sometimes - up to 50 km. It is clear that such spatial resolution does not give the picture of local peaks of ice pressure with spatial scale much less that the size of the grid cell. The aim of the presented paper is, basing on the model results with spatial resolution from 5 to 50 km, to study the statistical correlations between the ice pressure fields with various spatial resolutions, and to evaluate the possibility of calculating the intensity and probability of ice pressure peaks with spatial scale less than the spatial resolution of the model. In order to solve this problem, the numerical dynamic-thermodynamic model of ice cover evolution developed both for the entire Arctic Ocean and for large regions (the Barents and Kara Seas), and, for more detailed spatial resolution, for some smaller basins (the Pechora Sea, the south-western Kara Sea, the Baidara Bay), was used. The ice pressure fields within the same region and the same period of time were simulated with various spatial resolutions – from 5 to 50 km. The initial ice conditions were stated with the help the AARI ice charts which cover both the entire Arctic Ocean and the specific regions mentioned above. The comparison of model results with various spatial resolutions allowed revealing moderate statistical correlation between the average ice pressure obtained from the lower resolution model, and ice pressure dispersion obtained from the higher resolution one (correlation coefficients comprise from 0.3 to 0.7). This correlation is put into base of the main principles of calculating the extreme ice pressure in the spatial scale much less than the spatial resolution of the model. The statistical probability of the extreme ice pressure is strictly connected with the ratio between the spatial resolution of the model and the spatial scale of the extreme ice pressure to be estimated. For example, as the preliminary calculations show, if the spatial resolution of the numerical model equals 50 km, the extreme ice pressure in the scale of 1 km can exceed the mean value by 5–7 times. It gives on opportunity to obtain more comprehensive picture of ice pressure, and, as the method would be developed further, to increase significantly the informative value of the ice pressure forecasts. The limits of applicability of the proposed approach are discussed specificallyС помощью численной модели эволюции ледяного покрова рассчитаны поля сжатия с разными вариантами пространственной детализации. Выявлена статистическая связь между средним сжатием и пространственной дисперсией сжатия, полученными по моделям с низким и высоким пространственным разрешением. Предложена основа алгоритма оценки экстремального сжатия в масштабе меньшем, чем пространственное разрешение модели. Оговариваются границы применимости предложенного подхода
Результаты геодезических измерений баланса массы некоторых ледников Заилийского Алатау
Get PDFSummaryThe current state and mass balance of some glaciers of the Trans-Ili Alatau (Zailiyskiy Alatau, Tien Shan, Kazakhstan) is estimated in the paper. The remote sensing data (images of the Pléiades satellites) and detailed field geodetic measurements (differential global positioning system with the South G6 instrument)were used for the analysis. The field works were carried out in August-September 2021on the northern slope of the Zailiyskiy Alatau ridge. A digital relief model had been built for the analysis as well. Negative trends in the area of the studied glaciers have been revealed, which generally correspond to the average rate of degradation of the glaciation of the Trans-Ili Alatau from 1955 to the present. A comparison of glaciological (contact, i.e., obtained as a result of measurements made on the glacier) and geodetic (resulted from analysis of remote sensing data) methods for estimating the annual mass balance of the Central Tuyuksu glacier for the period 2016-2021 showed that the final values calculated by these two methods are very close in values. For example, the sum of annual balances calculated by the glaciological method for this period was -2.9 m w.e., or -0.58 a-1 m w.e. per a year, while the balance calculated by the geodetic method for the same period was - 0.63 a-1 m w.e. Thus, the results of comparison of the above methods of the glacier mass-balance investigation confirm that the geodetic one based on satellite measurements and the ground surveys using the South G6 instrument is in a good agreement with results of glaciological methods of measurements and calculations.Деградация оледенения вызывает изменения в горных экосистемах, оказывая непосредственное влияние на жизнедеятельность людей, вызывает изменения в гидрологическом режиме, биогеохимии рек и гляциальных озёр, влияя на качество и доступность водных ресурсов. Рассмотрены вопросы оценки баланса массы ледников северного склона Заилийского (Иле) Алатау посредством применения данных дистанционного зондирования Земли (ДЗЗ) в сочетании с полевыми исследованиями и измерениями
Профиль плотности снежно-фирновой толщи в районе станции Восток, Центральная Антарктида
Get PDFThe density of the snow and firn thickness is one of the fundamental and most important physical properties of the polar ice sheets. The data on density is used for reconstructing the past snow accumulation rate variability based on firn core studies, for correcting the results of the instrumental surface mass balance measurements and for verification of empirical and physical densification models. In this work we present a unique dataset on the snow and firn density in the upper 70 m of Antarctic glacier in the vicinity of Vostok Station based on data from 32 snow pits and firn cores. This newly obtained stacked density profile reveals different stages of the densification process. In the upper 27 cm a fast growth of the density is observed from 0.320 to 0.365 g cm-3 as a result of the initial snow grain metamorphism. Below 0.3 m much slower densification rates are observed. At the depth of 22.5 m the transition from snow to firn can be seen at the density of 0.526 g cm-3. The vertical density distribution can be approximated with a polynomial function with the accuracy of 0.01 g cm-3 along the whole profile except for the upper 0.3 m. In order to investigate the glacio-climatic conditions under which the snow-firn density has evolved, we applied a semi-empirical model by Herron and Langway (1980). In first approximation, the density distribution can be explained with the initial snow density equal to 0.35 g cm-3, surface glacier temperature equal to -57 C, and snow accumulation rate of 1.8–2.1 g cm-2 yr-1. The discrepancy between the data and model can be, to our opinion, explained by the recent increase of the snow accumulation rate as evidenced from the firn core studies. However, the non-stationary physical densification model failed to reproduced the density data with sufficient accuracy, which calls for revisiting the model configuration and tuning.Представлены данные о плотности снежно-фирновой толщи в интервале глубины 0–70 м в районе станции Восток (Антарктида). Охарактеризованы основные стадии уплотнения (быстрый рост плотности в пределах верхних 0,3 м, переход от снега к фирну на глубине 22,5 м). Выполнены тесты с помощью полуэмпирической и нестационарной физической моделей с целью изучения гляциоклиматических условий, при которых происходил