Ice and Snow (E-Journal) / Лёд и Снег
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Снежный покров как фактор роста годичных колец деревьев в контрастных природных условиях Западно-Сибирской равнины
Get PDFThe results of the analysis of the relationship between the width of annual tree rings of various woody plants and snow cover characteristics are presented: the dates of setting-up and destruction (loss) of stable snow cover, the duration of its existence, the thickness and water content of snow cover for the period of maximum snow accumulation. The studied areas are the forest-tundra zone, the northern taiga subzone, the southern forest-steppe subzone, and the dry steppe subzone within boundaries of the West Siberian Plain. Data from observations of snow cover on routes and meteorological sites of Roshydromet for 1966–2020 (for forest tundra and northern taiga) and 1966–2018 (for forest-steppe and dry steppe) together with dendrochronological samples obtained by the authors in these natural zones and subzones were used for this study. It was found that the thickness and water content of the snow cover play greater role for the radial growth of trees in the forest-tundra and dry steppe as compared to the northern taiga and southern forest-steppe. In the dry steppe, the trees of the upper parts of the low ridges and flat interfluves (plakors) are more sensitive to these snow cover characteristics, while in the forest-tundra this is important for the lower parts of the slopes. The dates of destruction of stable snow cover are more significant in the southern regions than in the northern ones. In the southern forest-steppe, the early loss of the snow cover increases the rate of growth of tree rings, while in the dry steppe it weakens it. The dates of setting-up of the stable snow cover are more important for the growth of trees compared to the dates of its loss, especially in the forest-tundra and southern forest-steppe since the later it starts, the greater the growth of trees. Importance of the duration of the period with stable snow cover for tree growth is higher in the southern regions. Its increasing in the southern forest-steppe reduces the growth of trees but increases in the dry steppe.Проанализирована зависимость ширины годичных колец древесных растений зоны лесотундры и подзон северной тайги (лесная зона), южной лесостепи (лесостепная зона) и сухой степи (степная зона) от таких показателей снежного покрова, как максимальная толщина и водозапас, даты установления, разрушения и продолжительность залегания устойчивого снежного покрова. Для анализа применены данные государственных метеорологических станций Росгидромета (далее – МС) за 1966–2020 гг. (по лесотундре и северной тайге); 1966–2018 гг. (по лесостепи и сухой степи); материалы собственных дендрохронологических работ
Ледники в горах России (Кавказ, Алтай, Камчатка) в первой четверти XXI века
Get PDFThe conducted studies allowed us to obtain a detailed picture of glaciation changes in the mountain regions of Russia, most provided with information about glaciers in the twentieth century. For the Caucasus glaciation, the data were obtained for the time periods 1911, 1952, 2000, 2014, 2018 and 2020; for Altai – for 1850, 1952, 2003 and 2018. For large glaciation nodes of the Central Altai – Katun, South and North Chuya Ridges additionally for 1968, 2008, and 2017. In both areas, a decrease in the area of glaciers since the beginning of the twentieth century and acceleration of the rate of reduction in the early twenty-first century have been revealed. The glaciers of the Caucasus and Altai reduced their size during this time by 46% and 48%, respectively. On average, in the twentieth century the glaciers of the Caucasus lost about 0.2% of the area per year, in the Altai – 0.15%, and in the early twentieth century 1.15 and 1.7% respectively. To study Kamchatka glaciers, we used data from the Glacier Inventory of the USSR (1950/1957) and images from different satellites in the period 2007–2019. The glaciers that were not previously registered in the Glacier Inventory of the USSR were identified. The greatest number of such glaciers is in the northern part of the Midnight Ridge, where out of 465 glaciers identified on modern satellite images, 216 were not included in the Glacier Inventory of the USSR. The area of glaciation in different regions of Kamchatka has changed extremely unevenly since the first cataloguing, which is associated with significant differences in glacier morphology. Glaciers of volcanic areas increased their size or remained stationary; here there is no tendency for glaciers to decrease due to the thick surface moraine consisting of volcanogenic material. Comparison of data from the Glacier Inventory of the USSR (as of the 1950s–70s) and the Glacier Inventory of Russia (2017–2019) shows a decrease in glaciation area from the mid-20th century to the end of the second decade of the 21st century in all mountainous regions of Russia except only the volcanic regions of Kamchatka. The area reduction ranges from 63% (Ural) to 13% (Kodar). The largest glacial systems of the Caucasus, Kamchatka and Altai have reduced their areas by 25, 22 and 39%, respectively.Проведённые в последнее время исследования позволили получить детальную картину изменений ледников в наиболее обеспеченных данными горных районах России. Для оледенения Кавказа получены данные на временные срезы 1911, 1952, 2000, 2014, 2018 и 2020 г.; для Алтая – на 1850, 1952, 2003 и 2018 г. Для крупных узлов оледенения Центрального Алтая – Катунского, Южно- и Северо-Чуйского хребтов дополнительно на 1968, 2008, 2017 г. В обоих районах выявлены устойчивое сокращение площади ледников с начала ХХ в. и ускорение темпов сокращения в начале ХХI в. Для исследования ледников Камчатки были использованы данные Каталога ледников СССР и снимки с разных спутников и за разные годы (2007–2019). Выявлено множество ледников, ранее не зарегистрированных в Каталоге ледников СССР. Площадь оледенения в разных районах Камчатки со времени первой каталогизации изменялась крайне неравномерно, что связано со значительными различиями в морфологии ледников. Ледники вулканических районов увеличили свои размеры или оставались стационарными; здесь нет тенденции к сокращению ледников из-за мощной поверхностной морены, состоящей из вулканогенного материала. Сравнение данных Каталога ледников СССР (1965–1982) и Каталога ледников России (2017–2019) показывает сокращение площади оледенения с середины ХХ в. до конца второй декады ХХI в. во всех горных районах России за исключением вулканических областей Камчатки
Двойная периодичность механических свойств тонкого ледяного поля, сформированного в условиях бокового стеснения
Get PDFExperimental data and results of theoretical modeling of the bending of a viscoelastic floating ice plate formed under constrained deformation are analyzed. When a thin plate of ice is frozen on the water surface under conditions of constrained deformation, which may be caused, for example, by the rigid walls of the pool, periodic changes in physical properties occur in it, in particular, periodic penetration resistance. Experimental results confirming this fact were obtained during tests of a thin ice cover at the Krylov State Research Center (Saint-Petersburg, Russia). A characteristic feature of the test results is that their spatial distributions can be represented with sufficient accuracy as an overlap of two periodic functions with significantly different periods: long-wave and short-wave components. In this paper, a detailed analysis of experimental data is given, which makes it possible to isolate these components. Furthermore, the theoretical model that explains the physical causes for double periodicity is proposed. The model assumes viscoelastic quasi-static deformation of the ice plate caused by small fluctuations of the water level in the basin and random disturbances of its surface. An analytical solution for the model case of cylindrical bending is derived. The solution is presented in the form of an expansion in terms of eigenfunctions of differential operators generated by the boundary value problem under study. It has been established that when a thin plate of ice freezes under conditions of constrained deformation, there are at least two reasons for the appearance of a periodic structure: a general loss of stability as an elastic structure and a local loss of stability by a viscoelastic-plastic mechanism. The results obtained can be used in the development of the theory of ice compression, in assessing the causes of variation in the local strength of ice fields and the possibility of their artificial destruction.Обсуждаются двойная периодичность (cжатие в плоскости ледяного поля и реологический характер локализации и накопления изгибных деформаций в нём), методы её экспериментальной идентификации, математическое моделирование и причины появления. Установлены две причины возникновения периодичности: общая потеря устойчивости упругой конструкции и локальная неустойчивость по вязкоупругому механизму. Первая зависит от геометрии пластины в целом и условий её закрепления, вторая - от толщины, усилия обжатия и физико-механических свойств льда
Внутрисезонная изменчивость абляции ледника Альдегонда (Шпицберген)
Get PDFThe intra-annual variability of the surface ice ablation on the 5.5 km2 Aldegondabreen glacier (Spitsbergen Island, Barentsburg area) is presented. The ice ablation was measured during five seasons (2018–2022) at the two stakes, installed in the lower part of the glacier and at the index site, where the amount of ablation numerically coincides with the glacier-averaged value with the r = 0.99 agreement. The temporal resolution of the ice ablation data is uneven and varies from 3 to 45 days. To carry out the correlation analysis, meteorological data from the automated weather station located near the glacier terminus are used. The ice ablation rates, obtained after normalization for the number of days between stake readings, have a tight correlation with both the air temperature and the downwelling shortwave radiation flux for most of the seasons, in 2018– 2021 (r = 0.71–0.99). Surface air temperature and short-wave radiation are closely related; the above estimates indicate the leading role of short-wave radiation in the summer ablation of the glacier in the period 2018–2021. The year 2022 became anomalous, as the correlation with the shortwave radiation significantly decreased (r = 0.21–0.34). The European heat wave of 2022, which also affected the Svalbard archipelago, interrupted the ordinary intra-annual variability of the air temperature, causing the unprecedented ice melt on Aldegondabreen in September. The predicted increase in frequency and intensity of the future heat waves will result in an increased role of turbulent fluxes in the surface energy balance of the low-elevated Svalbard glaciers. The article demonstrates how the empirically identified dependencies can change from season to season in a non-stationary climate.Рассмотрена зависимость внутрисезонной изменчивости абляции льда на леднике Альдегонда (Шпицберген) от приземной температуры воздуха и потока коротковолновой радиации. В 2018– 2021 гг. абляция льда хорошо согласуется с обоими факторами (r = 0.80–0.98 и 0.71–0.99 соответственно). 2022 год – аномальный с точки зрения нарушения связей абляции и радиации, что объясняется продолжительной волной тепла в Европе
Толщина льда и снежного покрова ледника ИГАН (Полярный Урал) по данным наземного радиозондирования в 2019 и 2021 гг.
Get PDFSmall glaciers of the Polar Urals are at the limits of their existence. Their state and changes serve as an important natural indicator of modern climatic changes. In 2019 and 2021, we performed ground-based radar studies of one of these glaciers, the IGAN Glacier, to measure ice thickness and snow cover. We used PicorLed (1600 MHz), and VIRL–7 (20 MHz) GPRs. According to these data, the glacier has an average thickness of 49 m, maximum 114 m. The glacier has a polythermal structure: a cold ice layer with an average thickness of 12 m (maximum 43 m), overlaps the temperate ice with an average thickness of 37 m (maximum 114 m in the upper part of the glacier). The volume of ice contained in the glacier (in its studied part) is 14.3 × 106 m3, of which 10.89 × 106 m3 is temperate ice and 3.44 × 106 m3 is cold ice. For comparison: according to the radar data of 1968, the total ice thickness then reached 150 m in the central part, and the thickness of the upper layer of cold ice was 40–50 m. Radar snow gauge survey allowed to build schemes of seasonal snow thickness distribution over the glacier surface in 2019 and 2021, where there is a general spatial pattern of snow thickness growth from 2 m on the glacier terminus to 8 m or more to the rear wall of the corrie, which is due to the significant influence of avalanche feeding and wind transport. The glacier has lost about 3.2 × 106 m3 of ice per last decade, if the rate of loss continues, it may disappear in 40–50 years. However, this process may have a non-linear nature, as it involves not only climatic factors, but also local terrain features, on the one hand contributing to a high accumulation of snow, on the other – the formation of a glacial lake during glacier retreat, which may increase ablation.В 2019 и 2021 гг. на леднике ИГАН проводились георадарные измерения толщины льда (ВИРЛ-7, 20 МГц) и снежного покрова (Пикор-Лёд, 1600 МГц). Показано, что ледник имеет политермическую структуру, а его толщина достигает 114 м. Выполнена оценка величины и особенностей распределения снежной толщи по площади ледника и прилегающей территории
Приледниковое озеро Бретъёрна (Западный Шпицберген): история формирования и современное осадконакопление
Get PDFThis paper presents the results of geomorphological, geochronological and lithological investigation of a young sedimentation basin – the periglacial Lake Bretjorna (Ledovoe). Formation of the lake began at the end of the first half of the 20th century in the west of Nordenskiöld Land (Western Svalbard) within the marginal zone of the Grönfjord glacier, after significant degradation of this glacial massif. The present-day look of the lake was formed at the end of the 20th century however its geomorphological development went on until the beginning of the 21st. The filling of the sedimentation basin with limnoglacial sediments began approximately from the 1930s and proceeded with spatial and temporal irregularity. Bottom sediments of the lake presented mainly by silty-pelitic material, but in places with an admixture of gravel and pebbles, were formed as the front of the Grenfjord glacier retreated in the direction from north-east to south-west. At the first stage, sediment-genesis was mainly accomplished by the intra- and subglacial sediments, which entered the lake as a result of thermal erosion at the contact of the lake and ice since the late 1940s until the end of the last century, as the present-day lake basin became ice-free. Sediments formed at this stage are composed by coarser and poorly sorted material, which is typical for glacial deposits. At the second stage, the sediments became less coarse and more sorted. After the loss of contact between the lake and the glacier, the role of intra- and subglacial sediments decreased. At this time, sedimentation in the lake goes on by the runoff of melted glacial waters and atmospheric precipitation falling on the catchment area of the lake. The value of the average sedimentation rate in the lake was determined by means of radioisotope dating according to 210Pb and 137Cs and amounted 5.4 mm/year in the north, 12.4 mm/year in the central part, and 16.4 mm/year in the south of the lake, which is comparable with the data obtained by gravity method using sedimentological traps (12–15 mm/year).Выявлены особенности геоморфологического строения озера Бретъёрна, установлены пространственно-временные периоды заполнения бассейна седиментации. Реконструировано развитие литотипов лимногляциальных отложений. Оценена современная скорость осадконакопления в озере от 5.4 до 16.4 мм/год
Моделирование орографической составляющей осадков на примере Эльбруса
Get PDFA model of the orthographic component of precipitation based on the calculation of the condensation rate of water vapor in the air stream uplifting onto the mountain slope is proposed. The main assumptions of the model are: the cooling of the rising air is determined only by the adiabatic process; the orographic component of the vertical component of wind speed is generated by the relief, and its weakening with elevation is determined only by the atmospheric stratification; the proportion of precipitation from the total mass of the condensed moisture depends only on the air temperature. ERA5 reanalysis, which was previously compared with observational data, is used as initial data. The proposed model adequately reproduces the spatial and temporal variability of precipitation on the Elbrus slopes both for short episodes and on the climatic time scale (1985–2018). Comparison of the modeling results with the reconstruction of the annual accumulation of precipitation from the ice core obtained on the Western Elbrus Plateau in 2018 showed a statistically significant positive correlation. However, similar comparison with the data from the core extracted in 2009 did not give a statistically significant result. This means that the proposed model can be used as a tool for conformity between methods of accumulation reconstruction and for substantiation of their physical justification (correctness). In addition, this algorithm can be used to calculate monthly and annual sums of precipitation on mountain slopes of various exposures and to estimate annual accumulation on mountain glaciers.Предложена модель орографической компоненты осадков, основанная на алгоритме расчёта скорости конденсации водяного пара в воздухе, вынужденно поднимающемся вдоль горного склона. В модели учтены затухание вертикальной компоненты скорости ветра, инициированной рельефом, в зависимости от стратификации, а также доля влаги, выпадающей в виде осадков, от общей массы конденсата. В качестве начальных данных применяется информация реанализа ERA5 (температура, характеристики влажности, компоненты скорости ветра). Показано, что предложенный алгоритм неплохо воспроизводит синоптическую изменчивость осадков, их сезонный ход и климатическую изменчивость, а также пространственное распределение по склонам Эльбруса. Выполнено сравнение годовых сумм осадков с реконструкцией аккумуляции по данным ледовых кернов, полученных на Западном плато Эльбруса. Предложенная модель может служить средством согласования методов реконструкции аккумуляции по керновым данным и их физического обоснования. Данный алгоритм можно применять для расчёта годовой аккумуляции на горных ледниках и в глобальных климатических моделях в качестве параметризации орографических осадков
Численное моделирование осаждения снега вблизи снегозадерживающих заборов
Get PDFThe results of numerical modeling of the influence of geometric characteristics of snow-protecting fences on the intensity of snow deposition at the initial stage of formation, that is, without taking into account the influence of the dynamics of the shape of the snow cover surface, are presented. In the most industrialized and densely populated region on the Arctic Krasnoyarsk Territory - the industrial City of Norilsk, daily snowfall can exceed 50 mm, the snow depth reaches, on the average, 47 cm (the largest is 70 cm), while the wind speed - 25-30 m/s. This promotes formation of snow deposition on roads, in residential areas as well as in industrial sites and infrastructure facilities, which hampers and sometimes completely stops operation of them. As part of the solution of these problems, a software package has been developed aimed at numerical modeling of snow transport processes and implementing the snow protection measures. To simulate the dynamics of the windinduced snow drift, a microscale model of the atmospheric boundary layer was used together with a diffusion-inertial description of the transport of the snow dispersed phase. Analysis of the calculation results shows that the width of the plates, as well as their spatial orientation, have insignificant effect on the snow-holding capacity of fences. The size of the gaps between the rails and the height of the lower gap exerts the greatest influence on the distribution of the intensity of snow deposition, both on the leeward and windward sides of the fence. In general, we can talk about the relationship between the wind speed field formed during the drift around the fence and the distribution of the snow deposition intensity. Thus, a relative decrease in the average wind speed from the leeward side of the fence increases the precipitation intensity. The presented results of numerical modeling do not contradict data of field observations previously obtained by other authors, and, thus, the developed software package allows comparing effectiveness of different snow-protecting constructions.Описывается математическая модель переноса снега ветром, реализованная в программном инструменте, предназначенном для разработки снегозащитных мероприятий. С его помощью проведено численное исследование влияния геометрических параметров снегозащитных заборов на интенсивность осаждения снега вблизи них. Показано, что наибольшее влияние оказывают просветность и высота нижнего зазора забора
Исследование характеристик поверхностного стока ледника Восточный Гренфьорд (Западный Шпицберген)
Get PDFSurface runoff on the glacier is represented by two aquifers: a hydro-network of streams and a porous layer of melting crust in which meltwater moves. The first one transfers water from the snowmelt zone, and the second one drains the ablation area. Data on the state of the melting crust at various levels of the glacier and the speed of water movement in it had been obtained. The water store in the melting crust were estimated, the effect of daily ablation on the runoff in the pores and micro-streams was shown. With a limited water supply in the melting crust, the increase in runoff takes place due to the formation of micro-streams having no channels. As the distance from the snow line increases and the ablation becomes more intensive, the portion of streams becomes greater. Observations on the glacier made at different levels showed a qualitative agreement with our estimates. As for the hydro-network, water discharges in watercourses of various sizes and the rate of water transit in them were estimated. It is shown that the meandering of the channels results in regulation of the rate of water transit. For small streams with water flow rate smaller than 200 l/s, this speed turned out to be 0.98 ± 0.25 m/s, for larger streams it was equal to 1.20 ± 0.11 m/s. Calculations of snow and ice melt based on the air temperature above the glacier made possible to estimate the channel runoff in both, the hydro-network, and the weathering crust. During the period of active snowmelt, when the snow line moves lower, the main contribution to the surface runoff is made by the hydro-network of watercourses. As the snow line rises and the area of open ice increases, the share of runoff in the weathering crust increases. By the end of the summer period, runoff in the weathering crust becomes predominant.Рассмотрены характеристики двух систем поверхностного стока полярного ледника – гидросети ледниковых водотоков и коры таяния. Полевые методы выявили принципиальные различия этих систем в отношении области дренирования, особенностях движения талой воды и режиме стока. Расчёт поверхностного стока показал – в гидросети максимум стока приходится на пик снеготаяния в июле, сток в коре таяния, наоборот, становится преобладающим во второй половине лета, в августе