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Распределение температуры и солёности морского ледяного покрова по экспериментальным и модельным данным (на примере бухты Новик Японского моря)
Get PDFAnalysis of sample distributions of temperature and salinity within depths of sea ice allowed revealing a high negative correlation between temperature of the surface air layer and the salinity vertical distribution across the ice thickness. Tis situation is explained by the fact that when temperature inside the ice rises the vertically oriented pores flled with brine, and this causes increased flow of brine. But when the temperature of the thickness drops, volumes of these pores signifcantly decrease, and as a result of that stresses near the pores grow and brine is squeezed out to both above and under the ice. Comparison of individual cases of the sample salinity distributions made possible to determine that the temperature of the surface air layer signifcantly influences the freezing intensity. When developing a model of spatiotemporal dynamics of the temperature, the diffusion mechanism of its vertical distribution is adopted, where the thermal conductivity coefcient is a linear function of temperature. A computational scheme for solving the model equations had been developed. Te procedure to estimate the model parameters is given. Te results of the parameter estimations had proved the adequacy of both the sample and the model distributions. A degree of the adequacy is the correlation coefcient between the above distributions. It is shown that the numerical simulation of the spatiotemporal salinity dynamics can be performed in framework of the diffusion mechanism of the vertical distribution, where the diffusion coefcient is a linear function of temperature. Te results of the parameter estimations did also show the adequacy of both the sample and the model distributions.Выполнен анализ выборочных распределений температуры и солёности ледяного покрова бухты Новик – типичной для Японского моря. Выявленные корреляционные связи между переменными использованы при построении численных моделей пространственно-временных распределений температуры и солёности. Рассмотрены вычислительные схемы решения уравнений моделей и процедуры оценки их параметров. Результаты моделирования показали адекватность выборочных и модельных распределений
ДИНАМИКА СНЕГОЗАПАСОВ НА РАВНИННОЙ ТЕРРИТОРИИ РОССИИ В ЛЕСУ И В ПОЛЕ ПРИ КЛИМАТИЧЕСКИХ ИЗМЕНЕНИЯХ
Get PDFIn 1966-2010, snow surveys were simultaneously performed in forests and fields on the Russian plain territory. This made it possible to analyze characteristics of snow storages on fields and in forests as well as a dynamics of them under the present-day climate changes. Data of 81 weather stations located on the territory were used. According to data of these stations for the period 2001–2010 we obtained the following estimates for the maximal snow storage values, on average: for 20 stations located on the European territory of Russia to the north of 60° N –167 mmin forests and 162 on fields; for 44 stations to the south of 60° N – 118 and116 mm, respectively; for 10 stations in the south of West Siberia – 125 and107 mm; and for 7 stations in the East Siberia – 64 and70 mm. As one can see the last region is characterized by the opposite relation between forest and field conditions. Comparison of these values with similar data for the period 1966-2000 demonstrated that maximal snow storages decreased in forests by 7% but in fields they increased by 2%. The ratio of the maximum snow storage in the forest to their value in the field (i.e. a coefficient of snow reserve) for the periods 1981–1990, 1991–2000, and 2001–2010 are 1.15; 1.11 and 1.03, respectively. One of the reasons for the equalization of snow storage in forest and field may be changes of intensity and duration of snowstorms. In the calendar winters of 2001-2010, the average number of observations at weather stations with wind speeds over 10 m/s decreased relative to 1966-2010: in the European part of Russia by factor of 8.9 times, and in Western and Eastern Siberia – by 2.0 and 1.9 times, respectively. In the European part ofRussia, the number of observation periods when wind speed from 6 to 10 m/s was observed decreased by 1.9 times.Проведено сравнение снегозапасов в лесу и в поле за десятилетия с 1981 по 2010 г. Для метеостанций с наибольшей изменчивостью коэффициента снегозапасов на Европейской части России, в Западной и Восточной Сибири установлены изменения по десятилетиям числа наблюдений на метеостанциях со скоростями ветра в диапазоне 6–10 м/с и более
История ледника Донгуз-Орун по биоиндикационным, историческим, картографическим источникам и данным дистанционного зондирования
Get PDFOn the basis of dendrochronological, lichenometric and historical data with the use of Earth remote sensing materials, the evolution of the Donguz-Orun Glacier has been reconstructed over the past centuries. In this work we used aerial photographs of 1957, 1965, 1981, 1987, satellite image of 2009, as well as descriptions, photographs, maps and plans of the glacier of the 19th and 20th centuries, data of instrumental measurements of the glacier end position in the second half of the 20th – early 21st centuries, dendrochronological dating of pine on the front part of the valley, and juniper to date coastal moraines, and the results of lichenometry studies. It has been established that the Donguz-Orun Glacier in the past had several clearly marked advances about 100, 200 and more than 350 years ago, which are expressed in relief in the form of uneven-aged coastal moraines. Despite the fact that the Donguz-Orun Glacier differs from many mountain-valley glaciers of the Caucasus primarily by its predominantly avalanche feeding and a moraine cover, almost entirely covering its surface, the main periods of its advances are consistent with the known large fluctuations of mountain glaciers during the Little Ice Age in the early 20th, early 19th, and, probably, in the middle of the 17th century. However, unlike most other Caucasian glaciers, the Donguz-Orun Glacier advanced in the 1970s–2000s. Te scale of its degradation from the end of the 19th to the beginning of the 21st century is also uncharacteristic for the Caucasus: the reduction in the length for longer than a century period is only about 100 m.Проведены исследования изменений долинного ледника Донгуз-Орун за последние три с половиной столетия. Границы положения конца ледника определялись по аэрофото- и космическим снимкам, а также по историческим описаниям, фотографиям, картам и планам ледника, дендрохронологическим датировкам по сосне и можжевельнику и результатам лихенометрических исследований. Установлено, что ледник Донгуз-Орун в прошлом имел несколько чётко выраженных наступаний около 100, 200 и более 350 лет назад, следы которых находят отражение в рельефе в виде разновозрастных береговых морен
ОСОБЕННОСТИ СЕЗОННОЙ И МЕЖГОДОВОЙ ИЗМЕНЧИВОСТИ ЛЕДЯНОГО ПОКРОВА ГРЕНЛАНДСКОГО МОРЯ
Get PDFThe results of studies of seasonal and inter-annual variability of the Greenland Sea ice cover are presented for the period from 1950 to 2016. Statistical characteristics of seasonal and inter-annual changes in the ice-covered area were calculated. Three clusters of typical seasonal variability were identified from the whole totality of all seasonal cycles. The first cluster presented a group of seasonal cycles in the period of maximum, the second one – the middle, and the third group – minimum areas of the winter ice cover. The estimates of correlation between changes in the ice areas in winter (February–March) or in summer (August–September) and areas of the following two months of a current year as well as in succeeding years were obtained. Empirical regularity of a variability of the ice cover during the annual cycle was established. This regularity is characterized by an existence of a ‘memory’ in the state of the ice cover, when a prehistory of the ice conditions determines to a certain extent the following phase. Analysis of inter-annual variability of the Greenland Sea ice cover did show a linear negative tendency in both winter and summer ice conditions. One-two year fluctuations were the most pronounced in the spectral density of inter-annual variations in the summer ice conditions. However, fluctuations with a longer period do also exist. With respect to contribution of hydrometeorological factors, the summer ice area is determined: (a) by conditions in the preceding winter, (b) by the atmospheric circulation, and (c) by the influence of warm Atlantic waters (about 20% of the total dispersion). Changes in the winter ice area depend: (a) mainly on the pre-winter state of ices (October–November), (b) on the influence of the Atlantic waters (about 30% of the total dispersion), and (c) on the heat balance and the atmospheric circulation (20% of the total dispersion). The results of this study may be used as a basis for the development of statistical models for analysis and prediction of long-term and climatic changes in the state of the ice cover in the Greenland Sea.Приведены результаты исследований изменчивости ледяного покрова Гренландского моря с 1950 по 2016 г. Проведена классификация внутригодовых циклов изменения площади ледяного покрова, выделены три кластера подобных сезонных циклов, получены линейные отрицательные тренды ледовитости, показывающие значительное уменьшение ледовитости за последние 66 лет
КЛИМАТИЧЕСКАЯ ИЗМЕНЧИВОСТЬ В ЭПОХУ МИС‑11 (370–440 ТЫС. ЛЕТ НАЗАД) ПО ДАННЫМ ИЗОТОПНОГО СОСТАВА (δD, δ18O, δ17O) ЛЕДЯНОГО КЕРНА СТАНЦИИ ВОСТОК
Get PDFThe results of detailed isotopic studies of ice core samples from the Vostok station (East Antarctica) related to the MIS-11 era (the 11th sea isotope stage, i.e. 370–440 thousand years ago) are presented. Reconstruction of paleoclimatic conditions in this period of time was performed using the method of interpretation of the results of isotopic studies of ice, developed by the authors of the article, which is based on the joint analysis of three independent parameters: δD, d-excess, 17O-excess. The isotopic composition (δD) and the deuterium excess depend on the following three meteorological parameters – the condensation temperature near the Vostok station, relative humidity, and the sea surface temperature at the source of moisture, whereas 17O-excess depends only on the first two parameters. Accordingly, the proposed method of interpretation allows reconstructing the paleoclimatic conditions (the condensation temperature and surface air temperature at the Vostok station; sea surface temperature and relative humidity above the ocean) in two different regions in past epochs. For the first time, data on minor fluctuations in the relative humidity of the air in themoisture source throughout the MIS-11 era were obtained. The data resulted from the interpretation demonstrated that the relative humidity fluctuated within the measurement error of ±5%. Reconstructed climatic conditions in the era of MIS-11 were compared with published data for stations Vostok and Concordia, aswell as with the marine core data from 94-607 DSDP and ODP 177-1090. The results obtained on the basis of isotopic analysis of ice cores from stations Vostok and Concordia indicated that in the optimum MIS-11the air temperature was4 °C higher, and in the Termination V –8 °C lower than the present-day values. Thesimilarity of data between the marine columns DSDP 94-607 (North Atlantic), ODP 177-1090 (South Ocean)and our results points to the global nature of changes in the sea surface temperature during the MIS-11 era. The coordination of the above results proves the high quality of the methods developed by the authors for measuring and interpreting the isotope composition of ice.Представлены результаты детальных изотопных исследований 2 тыс. образцов ледяного керна со станции Восток, относящихся к эпохе МИС-11 (370–440 тыс. л.н.). Обсуждаются методики измерения 17O-эксцесс на лазерном анализаторе, а также интерпретации изотопного состава, основанные на совместном анализе трёх независимых параметров: δD, d-excess и 17O-excess. Реконструированы климатические условия в окрестностях станции Восток и в месте испарения влаги (над океаном). Полученные результаты сравниваются с опубликованными результатами по станциям Восток и Конкордия, а также с данными по морским колонкам DSDP 94-607 и ODP 177-1090
Особенности формирования ледникового стока на северном макросклоне массива Табын-Богдо-Ола по изотопным данным
Get PDFThis investigation is based on measurements of stable isotopes concentrations (δD and δ18О) in water, snow and ice samples. Glaciers are composed of ice, snow, and fi n of atmospheric origin. The isotopic composition of these components is different, so when melting they form the melted glacial water with different isotope characteristics. Summer precipitation contains the heaviest isotopes, but only a small part of them remains on the glacier. The average isotopic composition of glacier ice represents the average composition of precipitation that accumulates on it. However, snow and fi n of different seasons can occur on the glacier surface, the isotopic composition of which differs from the isotopic composition of glacier ice. At different times of the ablation season different parts of the glacier melt, therefore the isotopic composition of melt waters will be different. Differences in the isotopic composition of the major runoff-forming components on the Northern slopes of the massif Tabyn-Bogdo-Ola had been identified. A part of melting ice in the formation of the runoff on this massif is determined by estimation of the isotopic composition of snow, ice, and fi n on different glaciers of this region. The average δ18О of snow on the glacier surface is −11.9‰, and this snow can be attributed to the precipitation fallen in late spring or early summer. Measured average isotopic composition of precipitation (δ18О = −11.9‰) was compared with the online calculator of the isotope content in precipitation (OIPC). The isotopic composition of glacial melt waters on the Northern macro-slope in the middle of July 2015 (δ18О = −15.3‰) differs from the isotopic composition of the territory of the Mongolian part of the massif (δ18О = −17.4‰) obtained from results of the analysis of eight samples taken at different edges of the glaciers at the beginning of August 2013. Isotopic separation shows important role of summer snow in feeding the glacial rivers of the massif even in the middle of the ablation season, especially for glaciers in the central part of the massif. The role of seasonal snow in feeding the glacier streams depends on the morphological type of glacier. It is maximum for corrie glaciers and minimum for the valley ones.Определены различия изотопного состава основных стокоформирующих компонентов на северном макросклоне массива Табын-Богдо-Ола. По изотопному разделению дана оценка доли ледникового стока в середине сезона абляции для крупнейших ледников массива. Выявлены отличия в изотопном составе талых ледниковых вод российской и монгольской частей массива, отмечена возможная связь между морфологическим типом ледников и долей талых снежных вод в стоке
О влиянии поверхностной морены на состояние ледника Джанкуат (Центральный Кавказ) к 2025 г.
Get PDFCurrent glaciation of the Central Caucasus is in the regressive stage of evolution. Observed long rising of the air temperature in the ablation seasons (almost 1 °C since 1968 on the Djankuat Glacier) together with insignificant growth of winter precipitation caused a long period of the glacier degradation: since 1871 the mass balance of the glacier, with rare exceptions, remained negative. During this time, the glacier has lost about 60 m w.e. mainly by areas of the smallest ice thickness, i.e. the steep slopes of the rocky framing of the fi n basin which become exposing from ice due to conditions of extreme instability. In parallel with the processes of freezing and thawing in cracks, this leads to a signifi ant increase in the frequency of rockfalls. In 2001–2003, huge rockfalls occurred on the glacier from the slopes, which had recently undergone deglaciation. The last one covered 4% of the glacier surface with about 70 000 m3 of clastic products. The marine cover differs significantly from the open ice surface in its thermal characteristics, which affect the structure of the thermal balance and the absolute values of ablation. The temperature inside the moraine is positive throughout the ablation season, even at a depth of 60 cm, but the absolute values of daily maximum melting are five times lower than those on open ice. The influence of the moraine material layer on the ablation is determined not only by its thickness, but also by the structure. The fi ld experiment conducted in 2011 demonstrated that melting under a layer of coarse-grained material (particle diameter 16–17 cm) is four times faster than under a layer of fi e-grained (7–8 cm) material equal in thickness. The study of the influence of the surface moraine and the account of its further growth in thickness and area made it possible to predict changes in the surface of the glacier by 2025. The climatic forecast was made using the HadCM3 model (A2 climate change scenario). Data on air temperature and precipitation were used to construct a predictive fi ld of the mass balance of the Djankuat Glacier for each year until 2025. Th s became possible by the use of a quantitative parameterized relationship between the mass balance of the entire glacier and each of its points, identifi d in the study of the total mass transfer of the glacier, as well as parameterized linear regression equations. The forecast of hypsometry of the Djankuat Glacier made it possible to determine that by 2025 the depression of the tongue areas covered by the moraine will be 7–15 m (or 42–45%) smaller than areas of the open ice. Th s means that at the present stage of the glaciation development the surface moraine plays a role in the evolution of the glacier, commensurable with the climate factor.Преобладание отрицательных значений баланса массы ледника Джанкуат за минувшие полтора столетия привело к значительному накоплению моренного материала на его поверхности. Поверхностная морена искажает структуру теплового баланса и влияет на изменение баланса массы ледника. В настоящее время поверхностная морена перекрывает 13% площади ледника и на 93% этой площади оказывает бронирующее воздействие. На основании климатической модели HadCM3 установлено, что к 2025 г. забронированные мореной участки языка будут понижаться на 7–15 м (или на 42–45%) медленнее, чем участки открытого льда. Ныне поверхностная морена играет в эволюции ледника роль, соизмеримую с климатическим фактором
ИЗМЕНЕНИЕ РАЗМЕРОВ И СОСТОЯНИЯ ЛЕДНИКОВ КАЗАХСТАНА ЗА 60 ЛЕТ (1955–2015 гг.)
Get PDFIn 1960–70s, a complete Inventory of the Kazakhstanglaciers had been prepared in the framework of the All-Union Glacier Inventory Program. All the morphometric parameters of the glaciers together with area and linear dimensions of them, and the absolute heights of characteristic points were determined from the 1:100 000 scale topographic maps and aerial photography of 1955–1956. In the late 1970‑s and in 1990, new inventories of glaciers of the Zailiysky and Dzungarian Alatau were prepared by the same procedure from the 1:25 000 scale topographic maps and aerial photography. Since the beginning of the 20th century, satellite images and GIS technologies were used for this purpose. In this work, the magnitudes and rate of changes in the number of glaciers, their areas and volumes, as well as their mass balance for 60 years (1955–2015) were obtained using data from different inventories. It was found that during the period under investigation the area of glaciation of Kazakhstandecreased from 1744.8 down to 1032.1 km2, i.е. by 712.7 km2. The relative decrease in the area of ice was 40.8% (0,68% per a year). The largest losses of the glacier areas took place on the northern slopes of the Zailiysky and Dzungarsky Alatau – 124.8 and 121.6 km2, respectively. The volume of ice decreased by more than 30 km3 (42.5%). The loss of the ice mass over the whole glacier area is approximately equal to20 m in the water equivalent. Data on the glacier degradation inKazakhstan obtained over the past 60 years provide the basis for monitoring of future glacier changes under conditions of the present-day climate.Из сравнения материалов Каталога ледников СССР (1955–1956 гг.) с более поздними определениями выяснены темпы сокращения оледенения за 60 лет. Площадь оледенения Казахстана за это время сократилась с 1744,8 до 1032,1 км2, т.е. на 712,7 км2. Относительное уменьшение площади льда составило 40,8% (0,68% в год). Больше всего сократились площади ледников на северных склонах Заилийского и Джунгарского Алатау (124,8 и 121,6 км2). Объём льда уменьшился более чем на 30 км3 (42,5%)
ГИДРОЛОГИЧЕСКИЙ РЕЖИМ ЛЕДНИКОВ В БАССЕЙНАХ РЕК СЕВЕРНОГО КАВКАЗА И АЛТАЯ
Get PDFRivers with snow-glacier alimentation in six basins of the Northern Caucasus (Cherek, Chegem, Baksan, Malka, Teberda, and upper course of the Terek River) and Altai (the Katun’ River) were investigated in 1946–2005 for the purpose to analyze long-term streamflow variations. It was noted that in 1976–2005 volume of annual runoff increased relative to the previous 30-year interval in four of six rivers of the Northern Caucasus. During the vegetation period the volume of runoff changed synchronously with the annual one. As for the river Katun’, its volumes and variability of both, the annual runoff and that for the vegetation season, decreased. In the course of investigation of spatial-temporal dynamics of hydrological and glaciological characteristics in the above river basins of the Northern Caucasus and the same of Katun’ River the following problems were considered and solved: a) the information and methodological basis for regional calculations of the runoff for the rivers with snow-glacier alimentation had been improved and corrected; b) changes of the components of hydrological cycle (precipitation, evaporation, and glacier runoff) over the glaciation area had been estimated for the period of 1946–2005; c) data on quality of the initial glaciological and hydrological information were integrated; d) definitions of the runoff were verified by means of comparison of measured runoff with similar values calculated by equation of the annual water budget as a whole for the basin. It should be noted that the total areas of glaciers and areas of their ablation were significantly reduced, but areas and thicknesses of ice under the moraine cover increased. Despite widespread, sometimes twofold decrease in the relative part of glacier alimentation in the total river streamflow for period of April–September this did make almost no effect on the water supply of the vegetation period in individual basins as well as in the whole the Northern Caucasus.Анализ изменения составляющих водного баланса в шести речных бассейнах Северного Кавказа и в бассейне р. Катунь на Алтае выполнен для двух временных интервалов: 1946–1975 и 1976–2005 гг. Метод определения составляющих водного баланса включает в себя модель сезонного стока от таяния снега и льда в областях аккумуляции и абляции ледников, а также комплекс расчётных формул для определения осадков, температуры и влажности воздуха, интенсивности таяния льда под мореной и открытого льда, испарения в интервалах высоты для основных типов поверхности на ледниках. Относительная разность между измеренным и рассчитанным стоком для бассейнов на Северном Кавказе составила в 1946–1975 гг. 2,6%, а в 1976–2005 гг. 8,9%