Ice and Snow (E-Journal) / Лёд и Снег
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Изотопный состав снега и льда на ледниках Новой Земли
Get PDFIn 2015–2016 during the research expeditions of Institute of Oceanology, Russian Academy of Sciences the study of stable water isotopes (18O and D) was conducted on glaciers of Novaya Zemlya. As a result, first data on isotopic composition of seasonal snow cover and glacial ice of different ages were obtained and its connection to recent climate change has been shown. The first studies of the isotopic composition of snow cover and glacial ice at Novaya Zemlya allowed determine the average values and the range of variability of δ18O and δD. It shown that for the Northern ice cap glacial ice δ18O vary within −13.91 ÷ −15.83 ‰ with an average value of −14.93 ‰ and −103,95 ÷ −116.75 ‰ for δD at −109.88 ‰ mean value. The maximum variations were recorded for summer snow samples (−8.35 ‰ for δ18O and −55.79 ‰ for δD), as well as for the horizon of superimposed ice (−20.67 ‰ for δ18O and −151.48 ‰ for δD) where isotopic composition has been inherited from winter precipitation. Insignificant differences in the coefficients of the meteoric water regression equation for precipitation on GNIP stations and glacial ice at Novaya Zemlya indicate similar conditions of air masses and precipitation formation both at GNIP station and on glaciers. Deuterium excess showed no seasonal fluctuations, and its values did not exceed 15 ‰, which shows that the proportion of continental precipitation of moisture is very low. Analysis of isotopic profiles obtained on the glaciers of Novaya Zemlya indicated the presence of significant melting. This applies not only to the modern shallow horizons, but also to the part of the glacial strata that formed in the highest part of the archipelago close to ice divide and came to the surface at the Serp i Molot Glacier tongue. Therefore, in terms of ice core palaeogeographic reconstructions the most interesting site is the highest part of the Northern ice cap where it is possible to assume the existence of colder horizons formed during the Little Ice Age and where the seasonal geochemical signal may be preserved.В 2015–2016 гг. проводились исследования стабильных изотопов 18О и D на ледниках Новой Земли. Установлены средние значения и диапазон изменчивости δ18O и δD. Показано, что для Северного ледникового купола величины δ18O в ледниковом льду варьируют в пределах −13,91 ÷ −15,83 ‰ при среднем значении −14,93 ‰. В изменениях эксцесса дейтерия не выявлено никаких сезонных колебаний, а его значения не превышают 15 ‰, что показывает крайне незначительную долю континентальной влаги в выпадающих осадках. Анализ изотопных профилей, полученных на ледниках Новой Земли, свидетельствует о значительном таянии
Обширная депрессия в леднике Долк, Восточная Антарктида
Get PDFIn the afternoon of January 30, 2017, the wide depression in the western part of the Dålk Glacier, East Antarctica, was formed. By coincidence, aerial surveying was carried out in this area, so it is possible to assess the extent of this catastrophic phenomenon. Aerial photos were taken on January 20 and February 9, 2017, respectively. Based on the photographic data, the size of the depression were 183 × 220 m, and its area reached 40.260 m2. The depth of the depression in the early days was 20–30 meters; the maximum measured depth was 43 m. An approximate volume of the cavern was about 884,013 m3. On preliminary conclusions, this event should be the similar jökulhlaups, when the water of Boulder Lake broke the icy border and rushed downstream under Dålk Glacier to Prudz Bay.30 января 2017 г. на участке дороги, соединяющей российскую станцию Прогресс и китайскую станцию Зонгшан с аэродромом и трассой следования санно-гусеничных походов на внутриконтинентальные станции Восток и Кунлун, в западной части ледника Долк (Dålk Glacier), в районе российской полевой базы Прогресс-1 образовался провал. Дана характеристика этого провала
Режим снежного покрова Предбайкалья в изменяющемся климате
Get PDFSpatial and temporal variability of dates of snow cover setting-up and loss (dates of the snow cover appearance and disappearance, and formation and destruction of stable snow cover) and duration of stable snow occurrence on a territory of the Baikal region were analyzed from data of observations made at meteorological stations in 1981–2010. Compared to the previous long-term period prior to 1980, mean monthly air temperatures rose in every month during the cold season. Significant changes in dates of the snow cover setting-up were observed only at individual stations, while the duration of the snow occurrence does not show such changes. Typical period of fluctuations for the last characteristic is the quasi-biennial, and more rare it is 3-4 years.In relation to the previous multi-year period, the largest variability of dates of the snow-cover setting-up as well as increase of number of dates and so duration of its occurrence (up to 19 days) take place on the South-West‑ ern coast of Lake Baikal (Bolshoe Goloustnoe). In plain and mountain regions of the Baikal region, variability of these dates does not exceed 10–15 days. Compared to the earlier period (before 1980), it was noticed that the snow appear earlier and disappear later (with the difference of about five days). In most cases, deviation of ear‑ lier dates of formation and destruction of stable snow cover is within 10 days. During 1981–2010, a number of days with snow cover increased in river valleys of the taiga belt in the Eastern Sayan (GMR Verchnyaya Gutara) by 11 days, while in the mountain Khamar-Daban (GMS Khamar-Daban) – by 15 days.Выполнен анализ изменчивости дат и продолжительности залегания устойчивого снежного покрова на территории Предбайкалья по данным наблюдений гидрометеорологических станций за 1981– 2010 гг. Наибольшая изменчивость дат образования устойчивого снежного покрова (до 19 дней), а также увеличение продолжительности залегания устойчивого снежного покрова по отношению к предыдущим многолетним периодам характерны для юго-западного побережья Байкала
Реконструкция динамики ледника Грёнфьорд (Западный Шпицберген) в голоцене
Get PDFIn the past 80 years, the Grønfjord Glacier front retreated for a distance longer than 2.5 km, and thus, a big part of the proglacial zone became free of ice. The detailed geomorphological survey of this zone made pos‑ sible to identify the following landforms: exaration-glacial, glacial-accumulative, exaration-extrusive, pushmoraine (thrusting), fluvioglacial and limnoglacial ones. Geomorphological analysis of the forms indicat‑ ing the Grønfjord Glacier movement and degradation allowed establishing its dynamics over the last glacial cycle. The river running from the moraine-dammed lake erodes a great thickness of a push-moraine (up to 20‑25 m) which is composed by marine sediments, accumulated on the site of the present-day proglacial zone under a relatively higher sea level than now. Careful investigation of lithology and stratigraphy of the push-moraine together with radiocarbon dating of marine shells resulted in determination of chronology of the main sedimentation stages during the Holocene within area of the present-day proglacial zone. During the reconstruction evidences of only two stages of the significant Grønfjord Glacier advance were revealed: in the early Holocene (9.5‑10 thousand years ago) and in the little ice age (before beginning of XX century), with the maximum advance at the last stage. Basing on the results of the reconstruction the suggestion had been made that during the little ice age the Grønfjord Glacier was a surging one.Представлены результаты изучения рельефа краевой зоны ледника Грёнфьорд. На основании анализа геоморфологической карты прогляциальной зоны по результатам дешифрирования аэрофотоматериалов и полевой геолого-геоморфологической съёмки реконструирована динамика последнего цикла наступания–отступания ледника в голоцене. Установлены только два этапа значительного продвижения ледника Грёнфьорд: в начале голоцена (9,5–10 тыс. л.н.) и в малом ледниковом периоде (до начала XX в.). Выдвинуто предположение о пульсирующем характере ледника Западный Грёнфьорд в последнюю фазу наступания
Атмосферная циркуляция в индоокеанском секторе Восточной Антарктиды за последние 200 лет по данным изучения химического состава снежно‑фирнового покрова
Get PDFSpatial and temporal variability of a sea‑salt aerosol (Na+) concentration was investigated in snow‑firn cores and snow pits taken at four sites of the Indian Ocean sector of the East Antarctica (along a profile between stations Progress and Vostok: PV‑10, NVFL‑1, SW‑42, and the Vostok point). In long annually resolved Na+ records, we had revealed the following periodicities: 17 to 95‑year (Vostok) and 29 to 52‑year (NVFL‑1), while the shorter records are characterized by 8‑year periodicity. The Na+ concentrations decrease as the snow accu‑ mulation increases (especially, at the Vostok station), and this is evidence for a presence of «dilution effect» in the sites with the great part of «dry precipitation». The closest relationship was revealed between changes in flows of Na+ at points SW‑42, and PV‑10. Variability of the Na+ fluxes had been linked to the circulation indices (AAO, PDO, SOI, MEI, SPO) and the sea level pressure in the Southern Hemisphere, as well as to occurrence of Elementary Circulation Mechanisms (ECM). The revealed irregularity of the Na+ precipitation over the area under investigation is caused by different atmospheric circulation patterns as well as by influ‑ ence of basic Action Centers of the Atmosphere (ACA) in the Southern Hemisphere. The closest relationship is found to take place with South Pacific ACA (Vostok, 1976–2009) and with the South Indian ACA (SW‑42 and PV‑10). A presence of distant atmospheric relations (including one with El Nino) had been revealed for the inland areas. Changes in features of the atmospheric circulation in the South Indian Ocean over the last 200‑year period have been reconstructed on the basis of summarized Na+ records from the Vostok station area. Distinctive feature of the atmospheric circulation is the 40‑year periodicity with its increasing intensity during the following periods: 1805–1820, 1830–1860, 1890–1900, 1940–1950, and 1980–2000. In addition, we had revealed that changes in the atmospheric circulation in the Indian Ocean (Southern Hemisphere) were synchronous with similar variability of the circulation in the Siberian (Northern Hemisphere) sector.По данным изучения химического состава снежно-фирнового покрова в индоокеанском секторе Восточной Антарктиды установлены пространственно-временные изменения аккумуляции морского аэрозоля (Na+). Исследованы корреляционные связи аккумуляции Na+ с индексами циркуляции и полем давления Южного полушария, а также элементарными циркуляционными механизмами. Впервые выполнена реконструкция интенсивности региональной циркуляции за последние 200 лет
Изменения горных ледников в Северном и Южном полушариях за последние 160 лет
Get PDFChanges of the glacier areas were analyzed. Rates of the area reduction of glaciers and glacier systems were compared over the course of the past 160 years as well as during shorter time intervals for the same period. On average for the whole period, the glacier areas decreased by a few tenths of a percent from the original in a year. Note, that this value was formed by rates for periods of the glacier retreating and advancing which were comparable by their intensities with rates from tenths of a percent to several percents of area in a year. In the first and the last thirds of the 20th century, when a rise of the air temperature decelerated, a number of advancing glaciers increased in both hemispheres. During these periods the same glaciers advanced (up to 25% of the total quantity of the investigated glaciers in the Alps). The second third of the 20th and the begin‑ ning of the 21st century were characterized by intensification of the temperature rise, and as the consequence of that, the number of advancing glaciers decreased, and rates of the area reductions increased over the whole globe. This dynamics was in a good agreement with the sea ice fluctuations in both, the Arctic and Antarctic regions, where the ice coverage increased in the 1960–1970 and in the second tenth of XXI century. So, decel‑ eration of the climate warming in that time was followed by increasing of the Arctic and Antarctic sea ice coverage and by deceleration of the area reduction of the mountain glacierization in some regions.Исследованы скорости перемещения фронта и изменения площади ряда ледников за последние 160 лет. В этот период на общем фоне сокращения горного оледенения число наступающих ледников возрастало при замедлении роста температур воздуха в первой и последней третях ХХ в. Во второй трети ХХ и начале XXI вв. отступание ледников усиливалось вместе с заметным ростом температуры воздуха. Такие изменения согласуются с колебаниями площади морских льдов, которая в 1960–70-х годах возрастала, а в середине ХХ и начале XXI вв. уменьшалась
Особенности изменений ледника Колка с 2002 по 2016 г.
Get PDFThe process of filling the bed with ice with steep lateral tributaries, which lost support, began almost immediately after the catastrophe on the Kolka Glacier in 2002. Currently, three streams of ice have closed in the rear zone of the circus, forming a single ice massif on the bed. The dimensions of the glacier vary under the influence of both new conditions for the accumulation and melting of ice, and the features of the dynamics of the ice masses filling the vacated bed. This paper describes the next stage of the state of the new Kolka glacier – relative stabilization – and analyzes the features of the process of its recovery based on ground‑based observations, modern space imag‑ ery materials, and calculations of changes in summer air temperatures and winter precipitation in the glacier area at the beginning of the 21st century. In recent years, the rate of increase in the area of the glacier does not exceed 0.015 km2 per year. By September 2016, its area reached 1.11 km2, the volume – about 0.044 km3. The conditions for the formation of a new glacier on the empty bottom of the circus differ significantly from the previous ones – when Kolka was restored in the 1970s after a pulsation. In addition to the background increase in summer tem‑ peratures, the thermal balance in the circus has changed due to an increase in the area of the open surface of the bed and lateral moraine, which increases the melting of ice. At the same time, the growth of the moraine cover on the glacier restrains the melting process. Rockfalls and avalanches enrich the glacier with detrital material with greater intensity than in the 1970s. The conditions of accumulation also changed – the volume of food supplied from the hanging glaciers decreased from the previous 31% to 17%. Fumarolic activity in the crown area of the starboard side of the circus is preserved and this prevents the restoration of these glaciers.По данным регулярных наблюдений в течение 2003–2016 гг. новый ледник Колка, возрождающийся в пустом цирке после гляциальной катастрофы 2002 г., в настоящее время стабилизировался. После 2010 г. увеличение его площади замедлилось и в последние годы не превышает 0,015 км2 в год, что на порядок меньше по сравнению с периодом 2005–2010 гг. Лишившись большей части висячих фирновых полей, ледник в настоящее время питается почти исключительно лавинным снегом. В период его восстановления, несмотря на повышение летних температур в цирке, таяние поверхности ледника сдерживается нарастающим сплошным моренным чехлом. На гребне правого борта цирка, у края фирнового плато, не прекращается активность фумарол – вулканогенные процессы в недрах Казбека продолжаются
Калибровка математических моделей лавин по данным о реальных лавинах в Иле (Заилийском) Алатау
Get PDFThe calibration of the dry friction and turbulent friction coefficients is necessary for computer simulation of avalanches. The method of back calculation based on data on actual avalanches is used for this purpose. The article presents the results of the calibration of the Eglit’s and RAMMS models for Ile Alatau range condi‑ tions. The range is located in Kazakhstan. The data on six avalanches in the same avalanche site were used. Five avalanches were dry, and one avalanche was wet. Avalanches volume varied from 2000 to 12000 m3. Maximum speed avalanches were between 15 and 30 m/s, the flow height – from 3 to 10 m. Series of back calculations with different values of the friction coefficients was made to obtain the calibrated coeffi‑ cients. The calibrated coefficients were chosen under condition of the best fit with real avalanches. The cal‑ ibrated coefficients were following. For the Eglit’s model for dry avalanches of the volume 2000–5000 m3 μ = 0.46÷0.48, k = 0.005–0.006, and the volume 8000–12000 m3 μ = 0.38÷0.42, k = 0.002÷0.003. For RAMMS model for dry avalanches of the volume of 2000–5000 m3 μ (dry friction coefficient) = 0.35÷0.4, ξ (viscous friction coefficient) = 1500÷2000 m/s2, and the volume 8,000–12,000 m3 μ = 0.3÷0.35, ξ = 2000÷3000 m/s2. For wet avalanches of the volume 12,000 m3 μ = 0.35, ξ = 1500 m/s2. The work on the calibration will be con‑ tinued to obtain the friction coefficients for the Eglit’s and RAMMS models. The additional data on real ava‑ lanches will be needed for this purpose.По данным о скорости, длине пути и высоте потока реальных лавин в Иле Алатау, полученных с помощью видеосъёмки во время профилактических спусков лавин, выполнена калибровка двух математических моделей лавин – М.Э. Эглит и RAMMS. Объёмы лавин варьировали от 2000 до 12 000 м3, скорости – от 15 до 30 м/с, высота потока – от 3 до 10 м. Методом обратных расчётов определены значения коэффициентов сухого трения и турбулентного сопротивления для лавин разных типов и объёмов. Получено хорошее совпадение расчётных дальностей выброса и скоростей движения лавин с фактическими. Расчётная высота потока была значительно меньше реальной
Регионализация данных глобального климатического моделирования для расчёта баланса массы горных ледников
Get PDFIn this paper, we consider a hybrid method of downscaling of the GCM‑generated meteorological fields to the characteristic spatial resolution which is usually used for modeling of a single mountain glacier mass balance. The main purpose of the study is to develop a reliable forecasting method to evaluate future state of moun‑ tain glaciation under changing climatic conditions. The method consists of two stages. In the first or dynamical stage, we use results of calculations of the regional numerical model HadRM3P for the Black Sea‑Caspian region with a spatial resolution of 25 km [22]. Initial conditions for the HadRM3P were provided by the GCM devel‑ oped in the Institute of Numerical Mathematics of RAS (INMCM4) [18]. Calculations were carried out for two time periods: the present climate (1971–2000) and climate in the late 21st century (2071–2100) according to the scenario of greenhouse gas emissions RCP 8.5. On the second stage of downscaling, further regionalization is achieved by projecting of RCM‑generated data to the high‑resolution (25 m) digital altitude model in a domain enclosing a target glacier. Altitude gradients of the surface air temperature and precipitation were derived from the model data. Further on, both were corrected using data of observations. Incoming shortwave radiation was calculated in the mass balance model separately, taking into account characteristics of the slope, i.e. exposition and shading of each cell. Then, the method was tested for glaciers Marukh (Western Caucasus) and Jankuat (Central Caucasus), both for the present‑day and for future climates. At the end of the 21st century, the air tem‑ perature rise predicted for the summer months was calculated to be about 5–6 °C, and the result for the winter to be minus 2–3 °C. Change in annual precipitation is not significant, less than 10%. Increase in the total short‑ wave radiation will be about 5%. These changes will result in the fact that the snow line will be higher than the body of the glacier itself. This will inevitably cause degradation of the glacier and its gradual disappearance. The main contribution to the glacier shrinking and disappearance will be made by air temperature rise, because it will affect the change in the ratio of the areas of ablation and accumulation. Besides, a rise of temperature will increase the average melting season duration. These are, of cause, preliminary results just to illustrate how the downscaling method works. We did not take into account dynamic effects and gradual reducing of the glaciated area. In future, we plan to couple mass balance and dynamical models [17] and to adjoin them with downscaled climate change in order to account for transient glacier changes.Предложен метод оценки изменения основных метеовеличин для прогноза параметров горного оледенения. Использованы результаты расчётов региональной климатической модели HadRM3P для Черноморско-Каспийского региона в условиях современного климата (1971–2000 гг.) и климата конца ХХI в. (2071–2100 гг.) по сценарию эмиссии парниковых газов RCP 8.5, выполненных в работе [22]. В качестве исходных данных в региональной модели использованы результаты глобального климатического моделирования для тех же периодов [18]. Представлены схемы расчётов для основных метеопараметров: осадков, температуры и коротковолновой радиации
Оценка потенциальных запасов пресной воды в айсбергах
Get PDFAccording to the forecast of the global shortage of fresh water it is expected that the global demand for drink‑ ing water will be increased up to 400 km3 per a year. As the main potential resources of drinking water it is proposed to use table Antarctic icebergs. Mathematical and phenomenological models of heat exchange between the icebergs and the environment, and a process of melting of ices floes in the warm sea water are discussed. The ablation processes on the daily and lower surfaces of icebergs at different modes of towing them to points of utilization is analyzed. The most optimal technology is to fill tankers with water taken from the freshwater layer under icebergs, and then subsequent delivery of the water to points of utilization. Using of the phenomenon of fresh-salt stratified Lake Vanda is considered as one of promising technologies of the industrial water production.В условиях растущего потребления пресной питьевой воды актуальны поиски новых её ресурсов. К ним можно отнести Антарктические столовые айсберги и пресно-солёные озёра антарктических оазисов. Приведена модель теплообмена айсбергов с окружающей средой. Показана бесперспективность буксирования айсбергов в пункты их предполагаемой утилизации. Выполнены оценки и расчёты утилизации айсбергов в водах Антарктики, которые доказывают устойчивость этого процесса за счёт эффекта «двойной» диффузии. Рассмотрена также модель использования эффекта пресно-солёного озера Ванда с устойчивой стратификацией плотности вод в поле силы тяжести