Radioglaciological studies on Hurd Peninsula glaciers, Livingston Island, Antarctica

We present the results of several radio-echo sounding surveys carried out on Johnsons and Hurd Glaciers, Livingston Island, Antarctica, between the 1999/2000 and 2004/05 austral summer campaigns, which included both radar profiling and common-midpoint measurements with low (20- 25 MHz)- and high (200MHz)-frequency radars. The latter have allowed us to estimate the radio-wave velocity in ice and firn and the corresponding water contents in temperate ice, which vary between 0 and 1.6% depending on the zone. Maximum ice thickness is ~200 m, with a mean value of 93.6 ± 2.5 m. Total ice volume is 0.968 ± 0.026 km3, for an area of 10.34 ± 0.03 km2. The subglacial relief of Johnsons Glacier is quite smooth, while that of Hurd Glacier shows numerous overdeepenings and peaks. The radar records suggest that Hurd Glacier has a polythermal structure, contrary to the usual assumption that glaciers in Livingston Island are temperate. This is also supported by other dynamical and geomorphological evidence

Экономическая оценка сезонной неравномерности загрузки железнодорожной инфраструктуры

The article considers the problem of seasonal uneven transportation and its impact on transport infrastructure loading. The objective of the study is to develop scientifically sound recommendations for monitoring seasonal unevenness of transportation and infrastructure loading based on its adequate assessment; conducting economic assessment of the impact of seasonality of transportation on the indicators of current and investment activity of railway transport; making recommendations to further reduce unevenness of transportation, or at least prevent its growth. The authors solved the following tasks: a reasoned, logically structured sequence of economic assessment of the impact of seasonality of transportation on the indicators of current and investment activities of railway transport was formed, and scientifically based recommendations were proposed to further reduce uneven transportation (toprevent its growth). The following methods were used: logical and analytical tools, methods of statistical analysis, economic-mathematical modelling and technical and economic calculations. As a result of the study, the authors revealed that seasonal uneven loading of railway infrastructure leads to a decrease in quality of transportation and a deterioration in the market image of the railway industry, an increase in operating costs and cost of transportation, that is, to a decrease in efficiency and competitiveness of railways. The uneven transportation negatively affects the effectiveness of investments in development of railway transport. The analysis made it possible to formulate a theoretical model of influence of seasonal unevenness of railway infrastructure loading on efficiency of its use and development. It is advisable to use the methodological toolkit for assessing seasonal unevenness of railway infrastructure loading for its in-depth retrospective analysis, identifying the main factors affecting unevenness indicators and determining the maximum permissible level of seasonal unevenness. The developed model of influence of seasonal unevenness of loading on use and development of railway infrastructure allows to carry out economic assessment of seasonal unevenness, is a tool to improve planning and management of transportation activities and development of railways. The reduction in seasonal unevenness of transportation should be considered as a factor increasing the economic efficiency of not only the current, but also investment activity of the railway transport, while its growth should be considered as a specific type of risk for effectiveness of implementation of railway infrastructure development projects.В статье рассматривается проблема сезонной неравномерности перевозок и влияние её на загрузку транспортной инфраструктуры. Целью проведённого исследования является выработка научно обоснованных рекомендаций по осуществлению мониторинга сезонной неравномерности перевозок и загрузки инфраструктуры на основе её адекватной оценки; проведению экономической оценки влияния сезонности перевозок на показатели текущей и инвестиционной деятельности железнодорожного транспорта; выработке рекомендаций по дальнейшему снижению неравномерности перевозок или, по крайней мере, недопущению её роста. Авторами решены следующие задачи: сформирована аргументированная, логически структурированная последовательность экономической оценки влияния сезонности перевозок на показатели текущей и инвестиционной деятельностей железнодорожного транспорта, и предложены научно обоснованные рекомендации для дальнейшего снижения неравномерности перевозок (недопущения её роста). При этом использованы следующие методы: логико-аналитический, методы статистического анализа, экономико-математического моделирования и техникоэкономических расчётов. В результате исследования авторы выявили, что сезонная неравномерность загрузки железнодорожной инфраструктуры приводит кснижению качества перевозок иухудшению рыночного имиджа железнодорожной отрасли, увеличению эксплуатационных расходов и себестоимости перевозок, то есть к снижению эффективности и конкурентоспособности железных дорог. Неравномерность перевозок негативно сказывается и на эффективности инвестиций в развитие железнодорожного транспорта. Проведённый анализ позволил сформулировать теоретическую модель влияния сезонной неравномерности загрузки железнодорожной инфраструктуры на эффективность её использования и развития. Предложенный в статье методический инструментарий оценки сезонной неравномерности загрузки железнодорожной инфраструктуры целесообразно использовать для её углублённого ретроспективного анализа, с выявлением основных факторов, влияющих на показатели неравномерности, и определением предельно допустимого уровня сезонной неравномерности. Разработанная модель влияния сезонной неравномерности загрузки на эффективность использования и развития железнодорожной инфраструктуры позволяет осуществлять экономическую оценку сезонной неравномерности, является инструментом повышения эффективности планирования и управления перевозочной деятельностью и развития железных дорог. Снижение сезонной неравномерности перевозок следует рассматривать как фактор повышения экономической эффективности не только текущей, но иинвестиционной деятельности железнодорожного транспорта, а её рост– как специфический вид риска для эффективности реализации проектов развития железнодорожной инфраструктуры

Ice thickness, internal structure and subglacial topography of Bowles Plateau ice cap and the main ice divides of Livingston Island, Antarctica, by ground-based radio-echo sounding

Ground-based radio-echo sounding studies of Livingston Island ice cap, Antarctica, were started in 1999 at Johnsons and Hurd glaciers, in Hurd Peninsula, close to the Spanish Antarctic Station Juan Carlos I. Radar profiling continued in 2000 and 2003 along the main ice divides of the ice cap and in the upper parts of Huron and another unnamed glacier, both draining Bowles ice plateau towards Moon Bay. More detailed radar studies on Bowles ice plateau were performed in December 2006 using an icepenetrating radar VIRL-6, with central frequency of 20 MHz, and a Ramac/GPR radar with 200 MHz antennae, intended for deep penetration to bedrock and shallow penetration to determine the firn layer thickness, respectively. The radar equipment was installed on two Nansen sledges and two pulkas towed by snowmobiles. Georeferencing of radar data was accomplished by using a GPS receiver working in stand-alone mode. The endpoints of the radar profiles were more accurately georeferenced using differential GPS. The data collected were used to construct the ice thickness, glacier surface and bedrock elevation maps and to estimate the average ice thickness and total ice volume of the plateau, as well as the spatial distribution of snow accumulation. For time-to-depth conversion, an average radio-wave velocity determined from common midpoint measurements at several locations in Hurd Peninsula was used. The thickest ice (550 m) was found in the upper part of Huron glacier. This thickness is almost twice the maximum thickness found along the main ice divides (330 m) and almost three times that found in Hurd Peninsula (200 m). The bedrock in two large areas in the northern and southern parts of the plateau, towards Moon Bay and Huntress glacier, lies below sea level, at depths down to -200 m, indicating that, should the ice cap fully disappear, several separated islands would likely appear, even if isostacic rebound is taken into account

50 лет геофизических исследований ледников в Институте географии

In 1967‑2015, Institute of Geography of the USSR/Russian Academy of Sciences together with other organizations carried out field expeditions in different areas of mountain and polar glaciations in many regions: the Polar Urals, Caucasus, Pamir, Zailiysky and Jungar Alatau, Tien‑Shan, Pamir‑Alai, the Kamchatka Peninsula, the Pyrenees, the Arctic – Spitsbergen, Novaya Zemlya, Franz Josef and Severnaya Zemlya, and Antarctica – on the ice flow B, and in the sub‑Antarctic – Islands King George, Galindez, and Livingston. The gravimetric and ground and aerial radar observations were made in these expeditions. About 300 glaciers of different morphological types and sizes with cold, subpolar and temperate thermal regime were studied. Basic results of these studies are the following: (1) the new data on the ice thicknesses, ice volumes, subglacial relief, internal structure, and thermal state of the glaciers were obtained; (2) the two‑layered (polythermal) glaciers consisting of the upper layer of cold ice and the lower layer of temperate water‑filled ice had been revealed in Svalbard for the first time; spatial distribution of cold, polythermal and temperate glaciers had been determined; (3) the evidences were obtained that measured changes in thickness of the upper cold ice layer in polythermal glaciers can be used to estimate the long‑period variations of regional climates and serve as regional paleothermometers; (4) methods for estimating the water content in temperate and polythermal glaciers from the RES data were developed; and its space‑time variations in temperate ices of the Svaldbald glaciers were estimated since even small water content inside of them can noticeably change their dynamic behavior; (5) methods for estimating the ice volume within glaciers in large regions of mountain and polar glaciations had been created; the ice storages were estimated in Svalbard, Franz Josef Land, Dzhungrsky Alatau, the Great Caucasus, and Mt. Elbrus; (6) detailed data on the ice thicknesses and the subglacial relief had been obtained for 40 glaciers in framework of different national and international programs and projects; the data can be used to solve a wide range of practical and theoretical problems, including numerical modeling. These studies demonstrated the following: (1) the use of monopulse radars VIRL‑6 and VIRL‑7 of decameter range (the central frequency is 20 MHz) with digital recording of the radar and GPS data is quite efficient for ground‑based and airborne (from helicopters) radio‑echo sounding of mountain and polar glaciers with their ice thicknesses up to 500–600 m; (2) it was found that thicknesses of glaciers in the Caucasus and Tien Shan can reach 330–430 m, while in regions of mountain, ice‑sheet and transitional glaciation on the Spitsbergen Archipelago – 300, 560 and 600 m, respectively, on the ice caps of the Franz‑Josef Land and Severnaya Zemlya – 450 and 813 m, and on King George and Livingston Islands (Sub‑Antarctica) – 330 and 500 m; (3) large parts of ice caps and outlet glaciers in Svalbard, Franz Josef Land, Severnaya Zemlya which beds were located below the sea level were found. Precisely these parts can be undergone quick shortening due to climate warming, and, thus, cause formation of icebergs making threats for ships and gas‑oil marine platforms in the Barents and Kara seas; (4) data of the measurements made possible to calculate volumes of a number of investigated glaciers and ice caps and to estimate the ice storages in large areas of mountain and polar glaciations (the Jungar Alatau, Great Caucasus, Spitsbergen, Franz Josef Land); (5) decreasing of glacier volumes on the Franz Josef Land and some Spitsbergen glaciers for the last decades had been estimated. Analysis of the data obtained had shown that considerable part of polythermal glaciers in Spitsbergen belong to type of surging glaciers; they have the winter englacial runoff and form the near‑glacier icings. It allows considering such glaciers as dynamically unstable, predisposed to surges as well as possible sources of winter water supply and additional sources of paleoinformation about long‑period variations of regional climate.Рассказано об истории и основных результатах геофизических исследований ледников, выполненных в Институте географии АН СССР/РАН в период с 1966 по 2016 г. группой специалистов по изучению толщины и строения ледников с применением геофизических методов. Такие данные необходимы для оценки запасов пресной воды в ледниках и их вклада в изменение уровня Мирового океана, а также для прогнозирования и реконструкции динамики ледников

Radio-echo sounding and ice volume estimates of western Nordenskiöld Land glaciers, Svalbard

As part of ongoing work to obtain a reliable estimate of the total ice volume of Svalbard glaciers and their potential contribution to sea-level rise, we present here volume calculations, with detailed error estimates, for ten glaciers on western Nordenskiöld Land, central Spitsbergen, Svalbard. The volume estimates are based upon a dense net of GPR-retrieved ice thickness data collected over several field campaigns spanning the period 1999-2012. On the basis of the pattern of scattering in theradargrams, we also analyse the hydrothermal structure of these glaciers

Оценка целесообразности тоннелей: теоретические аспекты

For the English abstract and full text of the article please see the attached PDF-File (English version follows Russian version).ABSTRACT The article substantiates the motives and significance of construction of new tunnels within strategic development of the network of Russian railways. The classification of railway tunnels based on the purposes of their creation and the types of generated effects is proposed. Approaches to assessment of feasibility of tunnels, which allow the «straightening» of the existing rai lway communication, improving its quality characteristics and efficiency, are considered. Based on the logical-analytical method, the spectrum of potential effects arising thanks to the construction of such tunnels at both the sectoral and macro levels is determined. Particular attention is focused on the choice of the calculation horizon and the discount rates. It is concluded that the construction of a railway tunnel can be considered expedient even with a long payback period of capital investments (15-20 years) in the case of a significant net discounted effect for the chosen calculation horizon. Keywords: railway tunnels, theory, construction, reconstruction, classification, feasibility assessment, discounting, remote effects.Текст аннотации на англ. языке и полный текст статьи на англ. языке находится в прилагаемом файле ПДФ (англ. версия следует после русской версии).В статье теоретически обосновываются мотивы и значение строительства новых тоннелей в рамках стратегического развития сети российских железных дорог. Предложена классификация железнодорожных тоннелей исходя из целей их создания и видов генерируемых эффектов. Рассмотрены подходы к оценке целесообразности тоннелей, дающих возможность «спрямления» существующего железнодорожного сообщения, улучшения его качественных характеристик и повышения экономичности. На основе логико-аналитического метода определён спектр потенциальных эффектов, возникающих при строительстве таких тоннелей как на отраслевом, так и на макроуровне. Особо акцентировано внимание на выборе горизонта расчёта и норм дисконтирования. Сделан вывод, что сооружение железнодорожного тоннеля может быть признано целесообразным даже при длительном сроке окупаемости капитальных вложений (15-20 лет) в случае значимого чистого дисконтированного эффекта

Диэлектрические свойства почв и грунтов и оценка их гидротермического состояния под снежным покровом по данным радиозондирования

Snow cover significantly affects the thermal regime of the underlying soils, and its assessment and monitoring are an urgent task of remote sensing studies. To solve it, data on their dielectric properties and their dependence on physical properties are necessary. Analysis of available data showed that the relative dielectric permittivity of soils most strongly depends on their moisture content and can vary from 2 to 40. This leads to a noticeable difference in the reflection coefficient from the interface between snow cover and dry and wet soils, which can be detected by radio-echo sounding. This opens up a new way to apply radar data to assess and monitor the hydrothermal state of soils under snow cover. Compilation of data on the typical reflectance properties of different soils in areas with permafrost and seasonal snow cover might be useful. The presence of wet snow cover on the surface of wet soils makes such systematic compilation more difficult.Выполнен обзор диэлектрических свойств сухих и влажных почв и грунтов и их зависимости от минерального и органического состава, температуры и содержания воды. Показана возможность оценки гидротермического состояния этих сред под снежным покровом по данным измерений коэффициента отражения от его подошвы и полезность обобщения сведений о характерных отражающих свойствах разных почв и грунтов в районах с сезонным снежным покровом и распространением многолетней мерзлоты

Скорость распространения радиоволн в сухом и влажном снежном покрове

In recent years, ground-penetrating radars are widely used for measuring thickness and liquid water content in snow cover on land and glaciers. The measurement accuracy depends on radio wave velocity (RWV) adopted for calculations. The RWV depends mainly on density, water content and structure of the snow cover and ice layers in it. The density and wetness of snow, and its structure can be estimated from data on RWV, using the available experimental and theoretical relations. Satisfactory results can be obtained using the Looyenga’s (1965) equations to estimate the density and wetness of snow cover, and equations of van Beek’s (1967) showing the distinction between RWV speeds velocities in snow cover and ice layers with different prevailing orientation and sizes of air or water inclusions.RWV in dry snow with density 300 kg/m3 may vary by 32 m/µs, depending on whether the vertical or horizontal orientation of the air inclusions prevails therein. In ice with density 700 kg/m3 effect of air inclusions orientation on differences in RWV is reduced to 5 m/µs. If the inclusions are not filled with air but with water, the difference in RWV in snow is 21 m/µs, and in ice is 24 m/µs. The RWV is affected not only by orientation of the inclusions, but their elongation. Twofold elongation of ellipsoidal air and water inclusions increases the difference in RWV in snow (with a density 300 kg/m3 ) to 23 m/µs and 22 m/µs.These estimates show a noticeable influence of snow structure on RWV in snow cover. The reliability of the above RWV estimates depends significantly on a thermal state of the snow cover, and decreases during snowmelt and increases in the cold period. It strongly depends on accuracy of measurements of the RWV in snow cover and its separate layers. With sufficiently high accuracy of the measurements this makes possible to detect and identify loose layers of deep hoar and compact layers of infiltration and superimposed ice, which is important for studying the liquid water storage of snow cover and a glacier mass balance. Therefore, considerable attention should be given to accuracy of the RWV measurements in dry and wet snow cover and its individual layers. With sufficiently high accuracy of measurements of the RWV, this should allow revealing such layers and estimating their thickness and average density.Представлены результаты расчётов скорости распространения радиоволн в снежном покрове в зависимости от плотности, влажности, структуры снега и прослоек в нём льда по разным эмпирическим и теоретическим зависимостям. Различие в скорости распространения радиоволн в сухом снеге плотностью 300  кг/м3 с преобладающей вертикальной или горизонтальной ориентацией включений воздуха достигает 32  м/мкс и уменьшается до 5  м/мкс во льду плотностью 700  кг/м3. Выполненные оценки показывают заметное влияние структуры на скорость распространения радиоволн в сухом и влажном снежном покрове, что позволяет обнаруживать и идентифицировать рыхлые слои глубинной изморози и плотные слои инфильтрационного и наложенного льда

Гидротермическая структура политермического ледника на Шпицбергене по данным измерений и численного моделирования

Thickness of the upper cold ice layer in the ablation area of the polythermal glacier Grønfjordbreen (Spitsbergen) was estimated by means of numerical modeling. The results were compared with data of radio-echo sounding of the same glacier obtained in 1979 and 2012. Numerical experiments with changing water content in the lower layer of temperate ice and surface snow cover thickness made possible to compare calculated and modeled cold ice thicknesses and to estimate their changes for 33‑year period caused by regional climate change. According to data of radio-echo sounding, thickness of the cold ice layer decreased, on average, by 34 m. Numerical modeling shown similar results: the cold ice layer became thinner by 31 m and 39 m at altitudes 100–300 a.s.l. under the snow cover thickness of 1 m and 2 m. We explain this by rising of annual mean air temperature by 0,6 °С as compared to data of the nearest meteorological station Barentsburg in the same period. We believe that changes in cold ice layer thickness in polythermal glaciers can be used for estimation of changes in such regional climatic parameter as mean air temperature at different altitudes of the glacier surface in the ablation area.Для политермического ледника Восточный Грёнфьорд на Шпицбергене выполнены численное моделирование толщины верхнего слоя холодного льда в области абляции и сравнение полученных результатов с данными радиозондирования за 1979–2012 гг. Согласно данным радиозондирования, слой холодного льда за 33‑летний период стал тоньше в среднем на 34 м. Численное моделирование показало аналогичные результаты: среднее сокращение слоя холодного льда на высоте 100–300 м над ур. моря составило 31 и 39 м при толщине снежного покрова соответственно 1 и 2 м, что объясняется повышением средней положительной температуры воздуха на 0,6 °С

Влияние снежного покрова на термический режим политермического ледника в условиях Западного Шпицбергена

Influence of snow cover, climate and glacier parameters on the cold-ice layer thickness and thermal regime in the ablation area of a polythermal glacier in Western Svalbard was investigated. Numerical modeling has demonstrated that a thickness of a cold layer in a polythermal glacier depends on a relation between the ablation on the surface and the freezing rate at the layer base. If the ablation rate is lower than that of the freezing, the layer thickness grows until the ablation and freezing rates become equal. Estimations show that in a case of slightly negative air temperatures on the glacier its cold-ice layer thickness increases when the snow cover thickness grows.Для условий Западного Шпицбергена на основе математического моделирования дана оценка влияния параметров снежного покрова, климатических условий и характеристик ледника на толщину холодного слоя политермического ледника и его термический режим в области абляции. Расчёты показали, что толщина холодного слоя политермического ледника зависит от соотношения абляции и скорости промерзания на нижней границе холодного слоя ледника. Если величина абляции меньше скорости промерзания на этой границе, то толщина такого слоя будет увеличиваться пока скорость промерзания не сравняется с величиной абляции. Проведённые расчёты показали, что в условиях небольших отрицательных температур воздуха на леднике с ростом толщины снежного покрова увеличивается толщина холодной части ледника