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Расчёт расхода массы Гренландского ледникового щита в модели земной системы
Get PDFMass discharge calculation is a challenging task for the ice sheet modeling aimed at evaluation of their contribution to the global sea level rise during past interglacials, as well as one of the consequences of future climate change. In Greenland, ablation is the major source of fresh water runoff. It is approximately equal to the dynamical discharge (iceberg calving). Its share might have still larger during the past interglacials when the margins of the GrIS retreated inland. Refreezing of the melted water and its retention are two poorly known processes playing as a counterpart of melting and, thus, exerting influence on the run off. Interaction of ice sheets and climate is driven by energy and mass exchange processes and is complicated by numerous feed-backs. To study the complex of these processes, coupling of an ice sheet model and a climate model (i.e. models of the atmosphere and the ocean) in one model is required, which is often called the Earth System Model (ESM). Formalization of processes of interaction between the ice sheets and climate within the ESM requires elaboration of special techniques to deal with dramatic differences in spatial and temporal variability scales within each of three ESM’s blocks. In this paper, we focus on the method of coupling of a Greenland ice sheet model (GrISM) with the climate model INMCM having been developed in the Institute of Numerical Mathematics of Russian Academy of Sciences. Our coupling approach consists in applying of a special buffer model, which serves as an interface between GrISM and INMCM. A simple energy and water exchange model (EWBM-G) allows realistic description of surface air temperature and precipitation fields adjusted to a relief of elevation of the GrIS surface. In a series of diagnostic numerical experiments with the present-day GrIS geometry and the modeled climate we studied sensitivity of the modeled surface mass balance and run off to the key EWBM-G parameters and compared our results with similar model studies. In addition to the atmospheric, oceanic, and ice sheet blocks the ESM normally contains blocks accounting for dynamics of the biosphere, sea ice, hydrological cycle, etc. In practice, application of ESMs for research studies has become possible not long ago owing to the fast progress in computing facilities. Nevertheless, still now ESMs are rather computer time demanding. To provide long runs of a fully coupled ESM at a lower computational cost, we utilized an asynchronous coupling when a 100-yr run of the GrISM corresponds to 1-yr run of the INMCM. The weak point of the numerical experiments is comparison of the results with observations. The lack of observations in Greenland and significant inter-annual variability of air temperature, precipitation, surface melting, and run off do not allow formulation of a reliable reference «climate» and corresponding equilibrium state of GrIS. In practice it means that more or less accurate estimates of the past or future changes of the runoff and total GrIS mass discharge is reasonable to obtain in the form of deviations from a reference undisturbed model state.Модель земной системы (ESM) – относительно новый инструмент исследования изменений климата. Наряду с традиционными для климатических моделей блоками – атмосферным и океаническим, она включает в себя блоки, описывающие динамику биосферы, морского льда и ледниковых щитов (ISM). В статье рассмотрена методика подключения модели динамики Гренландского ледникового щита GrISM к кли- матической модели (модели общей циркуляции атмосферы и океана, МОЦАО) INMCM Института вычислительной математики РАН в рамках проекта по созданию эффективной модели земной системы. Описаны процедуры для обеспечения двухсторонней связи между GrISM и соответствующими блоками INMCM. Исследована чувствительность расчётных полей баланса массы к некоторым модельным параметрам
Положения арктического фронта в периоды похолодания и потепления Арктики
Get PDFWinter positions of the Arctic front (AF) during the known periods of the climate cooling (1949–1980) and warming (1981–2012) were analyzed within the sector 10° W – 60° E. The AF positios were determined by the following indicators: 1) a surface pressure; 2) horizontal wind divergence; 3) geostrophic vortex; 4) geostrophic heat advection. The main extrema of these four dynamic characteristics coincide and fall on the latitude 72.5° N. This corresponds to the average position of the AF for a given resolution and confirms correctness of our choice of these characteristics as the AF indicators. Relative differences between mean profiles of all values of the above warm and cold periods were calculated using method of normalization of each value for the corresponding latitude by the standard deviation for the entire period (1949–2012). To study variability of the AF position we used mean yearly winter profiles of the variables under investigation together with the statistical analysis of positions of the extrema within the latitude degrees. For pressure and geostrophic advection positions of the absolute minima were determined while for geostrophic vortex and divergence – positions of the absolute maxima. The data show that according to different criteria the AF average positions for the period 1949–2012 lie within the zone 72.4–73.4 N. The interannual variability of the AF positions lies within the 1–2 degrees of latitude and corresponds to the range of the air temperature variability above the zone of maximal changes in the sea ice area. According to the standard deviation values of the divergence and the geostrophic vortex are the most stable in region of the AF passage. Comparison of differences of the studied characteristics between the warm and cold periods shows that the changes in the AF positions are not statistically significant (P(t) < 91% t‑criterion) unlike the changes in positions of isolines which characterize the warming (P(t) = 100%). Thus, despite significant changes in properties of the surface and the temperature regime to the north of 72.5 N (the warming), according to all the criteria the AF climatic position remains quasi‑stationary for 32‑year periods of averaging.Исследовано зимнее положение арктического фронта в секторе 10° з.д. – 60° в.д. в периоды похолодания (1949–1980 гг.) и потепления (1981–2012 гг.) Арктики. Положение арктического фронта определялось по положению минимума давления и геострофической адвекции, максимумам геострофического вихря и дивергенции ветра. Установлено, что разности в положении арктического фронта для периода потепления и похолодания статистически незначимы для всех перечисленных параметров и положение арктического фронта можно считать квазистационарным при значительном потеплении на 3–6 °С за 32 года
Аннотированная библиография русскоязычной литературы по гляциологии за 2014 год
Get PDFThe proposed annual bibliography continues annotated lists of the Russian-language literature on glaciology that were regularly published in the past. It includes 271 references grouped into the following ten sections: 1) general issues of glaciology; 2) physics and chemistry of ice; 3) atmospheric ice; 4) snow cover; 5) avalanches and glacial mudflows; 6) sea ice; 7) river and lake ice; 8) icings and ground ice; 9) the glaciers and ice caps; 10) palaeoglaciology. In addition to the works of the current year, some works of earlier years are added, that, for various reasons, were not included in previous bibliographies.Предлагаемая библиография продолжает ежегодные аннотированные списки русскоязычной литературы по гляциологии, которые регулярно публиковались в прошлом. Помимо работ текущего года, в списке встречаются работы более ранних лет, по тем или иным причинам не вошедшие в предыдущие библиографические списки
Дистанционное определение резервного объёма прорывоопасных высокогорных озёр
Get PDFResults of distant satellite sounding (the TERRA satellite) of high-mountainous areas and digital models SRTM 4.1 and ASTER DEM G2 of the same relief were used to calculate the following parameters of high-mountain dammed glacial lakes: area, depth, the water volume, excess of the dam above the water level. It is important for estimation of the water volume that can be dangerous for a break-through of a dammed lake. Formulas deduced to calculate the depth and volume of a lake for several sections of its area were tested and proposed. It is demonstrated that the regression equation V = Hmax × F, where Hmax is maximum depth of the lake, can be used as the parameterization of the formula «lake volume V equals the product of the area F on average depth D». More precise values of the coefficients a and b in the formula V = aFb were also obtained. Parameters and the water volumes of lakes were estimated for the river Gunt (right tributary of Pyanj River) basin. According to [28], there are 428 high-mountain lakes in this region with their total area ≥ 2500 m2. For basin Inflow of melted snow and glacier water caused by the rise of mean summer air temperatures in 1931–2015 was estimated for the lake Rivankul basin (the Pamir Mountains).Результаты дистанционного зондирования высокогорных территорий со спутника TERRA и цифровые модели рельефа SRTM 4.1 и ASTER DEM G2 использованы для расчёта параметров прорывоопасных озёр: площади; глубины; потенциального резервного объёма; превышения плотины над урезом воды. Получены и проверены формулы для расчёта глубины и объёма озёр для нескольких интервалов их площади. Показано, что в качестве параметризации формулы «объём озера V равен произведению площади F на среднюю глубину D» может быть использовано уравнение регрессии V = Hmax × F, где Hmax – максимальная глубина озера. Получены уточнённые значения коэффициентов a и b в формуле V = aFb. Параметры и резервный объём озёр определены в бассейне р. Гунт (правый приток р. Пяндж), где, по данным [28], находится 428 высокогорных озёр общей площадью ≥ 2500 м2. Для бассейна высокогорного оз. Риванкуль выполнена оценка притока талой снеговой и ледниковой воды в связи с ростом на Памире в 1931–2015 гг. средней летней температуры воздуха
Гляциогеофизические инженерные изыскания для подготовки лётного поля в районе российской станции Мирный (Восточная Антарктида)
Get PDFMain results of glaciological and geophysical engineering surveys, conducted during three summer field seasons of 2013– 2016 (59–61st Russian Antarctic Expeditions – RAE) near the Russian Station Mirny (East Antarctica), are discussed in the paper. Objective of these works was to site and then to organize a new airfield for landing of medium-range aircrafts with ski landing gears. Investigations included aerial photography, GPR surveys (georadar profiling), ice core drilling, and installation of landmarks to measure velocity of the glacier motion. The GSSI ground-penetrating radars with the main frequencies of 270 MHz and 900 MHz were used. In addition, special explorations were conducted for detecting the englacial crevasses by means of remote-sensing methods. The GPR data allowed a revealing the boundary between snow-andfirn thickness and atmospheric ice. In the course of processing of 252 travel-time curves of the diffracted waves a kinematic model of the sub-surface part of the glacier has been constructed. It was found that the dielectric permittivity of the snowfirn thickness averages 2.43; similar value for the atmospheric ice amounts to 3.0. The GPR data made it possible to determine intraglacial (englacial) crevasses and to choose the most favorable field for the landing. On February 10, 2016, the first middle-range aircraft DC-3T (BT-67) had landed onto the new run-way near the station Mirny.Рассматриваются результаты гляциогеофизических инженерных изысканий в трёх летних полевых сезонах 2013–2016 гг. (59–61-я Российские антарктические экспедиции) в районе станции Мирный (Восточ- ная Антарктида). Цель работы – выбор места посадочной площадки для приёма среднемагистральных самолётов на лыжном шасси и последующая её организация. Работы предусматривали проведение аэрофотосъёмки, георадарного профилирования, кернового бурения, а также установку вех для изме- рения скорости течения ледника. Георадарные данные позволили выявить внутриледниковые трещины и выбрать наиболее удачное место для посадочной площадки, на которую 10 февраля 2016 г. был принят самолёт DC-3Т (BT-67)
О преимуществах бассейнового подхода при изучении закономерностей распространения наледей
Get PDFFormation of aufeises (naleds) is rather widely distributed cryogenic process in the permafrost zone, therefore naleds are reasonably called the seasonal glaciation of the planet. The ever-increasing interest in aufeises significantly extends the thematic focus of studying them. Various methodological approaches (basin, geological-structural, lithologic-facies, statistical, etc.) are used to reveal regularities of the aufeis occurrence. Using several river basins in Yakutia and its territory as the examples, the perspectivity of the basin approach for investigation of the aufeis distribution is substantiated in this study. The results demonstrated the clear relationship between the quantitative indicators of areal distribution of naleds and altitudes of places of their formation for individual river basins. This relationship suggests that aufeises in river basins of the permafrost zones are important elements in the water-balance and water exchange, which is closely interrelated with not only climatic and morphometric characteristics of a basin, but it does also correlate with its hydrological, hydrogeological, geological, geocryological, landscape and other conditions.Для конкретных речных бассейнов Якутии и территории республики в целом автором рассчитаны количественные показатели площадного распространения наледей и высотного распределения мест их формирования. Выявленные закономерности подчёркивают, что наледи представляют собой важный водно-балансовый и водообменный элемент речных бассейнов криолитозоны
Современные тенденции природных процессов в полярных областях Земли и перспективы российских полярных исследований: 11-я конференция в Сочи
Get PDFOn 5–7 October 2015 the All-Russian scientific conference «Results and prospects of studying natural environment in the Russian Arctic and other polar regions» was held in Sochi (south Russia). The conference was attended by about 80 scientists from different organizations of Russia. The reports presented the results of investigations performed during the last years. This review summarizes the main ideas and results of research in the field of glaciology and permafrost studies of the Arctic.5–7 октября 2015 г. в Сочи была проведена Всероссийская научная конференция «Итоги и перспективы изучения природной среды Российской Арктики и других полярных областей». В конференции приняли участие около 80 учёных из разных организаций России. В докладах были представлены результаты работ последних лет. В настоящем обзоре кратко излагаются основные идеи и результаты исследований в области гляциологии и геокриологии Арктики
Оценка водного эквивалента снега по данным пассивного микроволнового сканирования земной поверхности с использованием искусственных нейронных сетей для территории Российской Федерации
Get PDFUsing of the Chang model for calculation of the snow water equivalent on the basis of measurements of the Earth thermo-microwave radiation by means of scanning polarimeters (SMMR, SSM/I, AMSR-E) from board of orbital satellites does not allow obtaining the accuracy needed hydrological purposes. Low accuracy of the calculations is caused by both simplified character of the mathematical model, and due to significant influence of the surface characteristics (relief, vegetation and complex structure of snow thickness) upon the microwave radiation propagation. This work was aimed at finding a way to increase accuracy of calculations of the snow water equivalent on the Russian Federation territory with its different climate conditions by means of application the neural network approach for processing of results of the passive microwave scanning of the Earth surface. Feed-forward multi-layer artificial neural network was trained by back-propagation algorithm using SSM/I data and results of snow water equivalent in situ measurements obtained at 117 meteorological stations during the period from January 1st, 1988 till December 31st, 1988. Validation was performed using data from the same sources collected during 7 years (1992–1998). Results of performed numerical experiments and obtained values of rootmean-square error (σ = 24.9 мм; r = 0.39±0,01) allow coming to conclusion that the best estimation of water equivalent of a snow cover is provided by artificial neural network using as the input data a set of the SSM/I channels 19.35, 37.0, 85.5 GHz of horizontal and vertical polarizations with meteorological data differentiated by types of the snow survey route.It is shown that low correlation coefficients (< 0.5) as compared with similar studies on small areas is not caused by the chosen mathematical model and its realization but it is due to a strong diversity of climatic conditions and low density of meteorological stations on the land areas covered by our study. For the purpose of further improvement of quality of the snow water equivalent calculations as for diminution of negative influence of the above factors we propose to use the artificial networks ensemble trained by results of direct measurements grouped according to characteristics of the climate conditions, relief and vegetation.Формулируется проблема оценки накопленных снегозапасов на обширных, климатически разнообразных территориях. Предложено использование искусственных нейронных сетей для восстановления водного эквивалента снежного покрова на основе микроволнового спутникового зондирования и опорных данных снегомерных съёмок. Подход апробирован для территории Российской Федерации
Гидротермическая структура политермического ледника на Шпицбергене по данным измерений и численного моделирования
Get PDFThickness 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
Кто «открыл» озеро Восток?
Get PDFA history of the subglacial lake Vostok that had been revealed near this Soviet Antarctic Station is briefly described in the paper. Three participants of the Soviet Antarctic Expeditions played a significant part in the history of the Lake discovery, and they were a navigator of polar aviation R.V. Robinson, a physicist I.A. Zotikov, and a geographer A.P. Kapitsa. R.V. Robinson was the first man who had indicated to evidence of a subglacial lake in contours of the glacier surface; I.A. Zotikov had substantiated a hypothesis of a subglacial melting in central regions of the Antarctic continent and possible presence of water bodies in depressions of the glacier bed; A.P. Kapitsa had obtained by means of seismic sounding the original reflections which were later interpreted as reflections from subglacial water layer. And lastly, in some time later, the Britain glaciologist G. Robin had performed the thorough radio sounding in the vicinity of the Vostok station and finally proved existence of a large subglacial water body in this region. Further on, the lake was investigated by many participants of the Russian Antarctic Expeditions, as well as by scientists from the Britain Scott Institute and members of the American Antarctic Expeditions. Now this is the largest and the mostly studied subglacial lake in the Antarctica among almost 400 similar lakes revealed under the ice sheet.Изложена история открытия подледникового озера Восток, обнаруженного в районе одноимённой советской антарктической станции. В истории открытия озера главное значение имеют три имени участников советских антарктических экспедиций: штурмана полярной авиации Р.В. Робинсона, физика И.А. Зотикова и географа А.П. Капицы. Дальнейшие исследования озера выполнены многими участниками Российских антарктических экспедиций, учёными Британского полярного института имени Р. Скотта и членами американских антарктических экспедиций. Сейчас это самое крупное и наиболее изученное подледниковое озеро в Антарктиде из почти 400 таких же озёр, обнаруженных под ледниковым щитом