Колебания ледников в голоцене и возможное влияние на них орбитального сигнала, солнечной и вулканической активности и антропогенного воздействия

The magnitude of glacier advances generally increased in the Northern Hemisphere and decreased in the Southern Hemisphere over the Holocene. This trend can be explained be the orbital forcings. The exceptions are in some regions of the high Asia. 10–4 ka BP and during the 1th Century CE to the early 13th century CE the glaciers were close by sizes to the modern ones or even smaller. The pattern is confirmed by the upper and Northern tree line advances in the Northern Hemisphere. The period with generally «small glaciers» (5–7 ka) coincides with the lack of the major volcanic eruptions, and with the low solar activity. The Early Holocene moraines cluster in seven groups (from 11.1 to 8.1 ka BP). They coincide with all Early Holocene Bond cycles (11.1, 10.3, 9.4, 8.1 ka) and all major volcanic eruptions (11.0, 9.5–9.7, 9.1–9.3, 8.0–8.1). Due to the coincidence of several eruptions with the Bond cycles (solar minima) it is difficult to distinguish between the solar and volcanic signals in the Early Holocene records. The coupling between the glacial and solar/volcanic forcings in the mid Holocene is less evident, but it become strong again in the last 2 ka (1.4 ka and LIA events).  The modern glacier retreat disagrees with the actual orbital forcings and is due to both solar and anthropogenic influence. Glacier variations at the moment do not provide proofs for any cycles or global synchronism through the Holocene. However the lack of such evidences can be also explained by the limitations of these records (discontinuous, incomplete, of low accuracy, showing a mixture of advances triggered by both temperature and precipitation).Амплитуда наступаний ледников в голоцене в Северном полушарии в целом увеличивалась, а в Южном – уменьшалась. Этот тренд объясняется изменениями инсоляции, связанными с орбитальными параметрами Земли. Исключение из этого правила – некоторые районы Центральной Азии, где размеры ледников в голоцене уменьшались. 10–4 тыс. л.н. и в течение первого тысячелетия н.э. (примерно до начала XIII в.) размеры ледников были близки к современным или были меньше их. Этот тренд подтверждается данными о колебаниях верхней и северной границ леса в Северном полушарии в голоцене. Период (7–5 тыс. л.н.), когда ледники имели небольшие размеры, а их наступание почти нигде не зафиксировано, совпадает с периодом отсутствия крупных эксплозивных извержений и низкой солнечной активности. Раннеголоценовые морены (период от 11,1 до 8,1 тыс. л.н.) объединяются в несколько групп и совпадают с циклами Бонда (11,1; 10,3; 9,4; 8,1 тыс. л.н.) и крупными вулканическими извержениями (11,0; 9,5–9,7; 9,1–9,3; 8,0–8,1 тыс. л.н.). Из-за совпадения некоторых извержений с циклами Бонда (которые в свою очередь совпадают с минимумами солнечной активности) влияние вулканической деятельности и солнечной активности трудно разграничить. Влияние солнечной и вулканической активности на поведение ледников в среднем голоцене неочевидно, но в последние два тысячелетия (событие 1,4 тыс. л.н. и малый ледниковый период) корреляция вновь становится заметной. Современное отступание ледников не согласуется с современным орбитальным сигналом, но связано с ростом солнечной активности и концентрации парниковых газов. Колебания ледников в разных районах не обнаруживают глобальной синхронности и строгой периодичности в течение голоцена. Однако отсутствие таких свидетельств может быть связано также с ограничением данных о колебаниях ледников (дискретные ряды, неполнота данных, низкая точность датирования, влияние температуры и осадков на колебания ледников др.)

Using information-communication technologies in educational process organization

© 2017. revistaESPACIOS.com. The article addresses the influence of informationcommunication technologies on the development and improvement of informational-educational environment of a modern university. It defines the tendencies of further development and methods of information and Internet technologies' application in informationaleducational environment of a university. The article presents and analyzes the results of a survey among students with the aim of revealing the level of activity in using informational-educational environment in the educational process. The following phenomena were defined as the tendencies of the development of informational-educational environment of a university: processes of converting universities' documents, document flows and communication channels to the electronic format; active introduction and use of electronic educational and educational-methodic documents; decrease of expenses related to the support of communication process, increase of its efficiency and accessibility of its results not only for university students and teachers but for the society in general by using the "free ware" type software. Control of students' knowledge is an important stage in the educational process. If the tests are designed correctly, students' knowledge, abilities and skills are reflected in the performance of the control tests' tasks. Knowledge control in the StartExam program is one the possible ways of increasing the efficiency of students' knowledge control and teacher's work capacity

Абсолютный и относительный возраст морен стадий Актру и Историческая ледников Центрального Алтая по данным лихенометрии и дендрохронологии

Dendrochronology, and lichenometry were used to determine the relative and absolute age of the Late Holocene moraines of the glaciers of the Aktru, Maashei and Shavla valleys (North Chuya ridge, Central Altai). An array of 86dendrochronological dates, related to moraine deposits, is analyzed, 30 of which are published for the first time. Also, for the first time, data on the relative (lichenometric) age of the young deposits of the Aktru Valley, and data on the lichenometry of the moraines of the Maashey glacier and one of the glaciers of the Shavly valley were obtained. We used the capabilities of each method and the expediency of their combined use in the study area. It was confirmed that the growth rates of lichens on the moraines of the Aktru stage (XVIII–XIX centuries) are generally consistent with the previously published estimates. The moraines of the Historical stage, which date earlier than 1700–2300 years ago, supports the lichens as large as 120–160 mm, but the scattering of their diameters is too large and the assessment of the lichenometric ages of these moraines seems to be problematic, but not completely excluded. The Akkem stage of glacier advance according to the recent publications dates back to the Late Glacial or Early Holocene time; the lichenometry is obviously not applicably at such ancient surfaces. According to dendrochronological dating, the glaciers of the North Chuisky Ridge in the last millennium advanced at least twice up to their maximum extent in the XVII– early XIX and XII centuries. In the 8th century, the sizes of the glaciers possibly, approached modern ones. Aſter the XVII century, the cedar (Pinus Sibirica) in Central Altai significantly reduced its distribution area due to the climate cooling, retreating from the periglacial territories, where it was distributed earlier. All trees that grew near the glaciers, above 2300 m, died. The comparison of the dates of glacier advances in the past millennia with the tree-ring, ice-core, and palynological reconstructions of summer temperature and precipitation show a good correspondence.Методы дендрохронологии и лихенометрии применены для определения относительного и абсолютного возраста позднеголоценовых морен ледников Центрального Алтая (Северо-Чуйский хребет). Установлено, что скорости роста лишайников– индикаторов на моренах стадии Актру– в целом согласуются с опубликованными ранее оценками. По данным дендрохронологического датирования, ледники этого района в последнем тысячелетии имели два максимума наступания: в XII в. и в XVII– начале XIX вв. (максимум продвижения). В VIII в. площадь ледников приближалась к современной. Размеры лишайников подрода Rizocarpon на моренах стадии Актру варьируют от 20 до 41 мм, на моренах Исторической стадии– от 120 до 160 мм, что в спорных случаях позволяет однозначно идентифицировать морену

История ледника Алибек по данным дистанционного зондирования, биоиндикации, 14С и 10Be датирования

In this article we present the reconstruction of fluctuations of Alibek valley glacier situated in the Teberda valley, Western Caucasus. The former positions of glacier of the past 120 years were reconstructed basing on the old photographs of 1904, 1921, remote sensing data of 1955, 1987, 2007, 2008 and 2012, plans created in 20th century. Since the middle of 20th century Alibek Glacier decreased by 650 m in length and by 0,67 km2 in area and its tongue has risen by 110 m.Приведена реконструкция колебаний долинного ледника Алибек, расположенного в долине р. Теберда на Западном Кавказе. Источником информации о положении конца ледника служили фотографии 1904, 1921, 2004 и 2008 гг., космические и аэрофотоснимки 1955, 1987, 2007, 2008 и 2012 гг. На этой основе реконструировано семь положений языка ледника за последние 120 лет. С середины XIX в. ледник Алибек сократился в длину на 650 м, по площади – на 0,67 км2, а высота конца ледника повысилась на 110 м

Динамика нивально-гляциальных склоновых процессов в бассейнах рек Баксан и Теберда по данным радиоуглеродного датирования погребённых почв

Radiocarbon and tree-ring dating of the soil horizons, buried in the slope and fluvioglacial deposits in Baksan and Teberda valleys, bring evidence of the reduction of the avalanche activity, stabilization of the slopes and soil formation on their surfaces. In the Baksan section three such horizons are identified, while in the Teberda section only one. The radiocarbon dates of the two thickest soil horizons in the Baksan section are 170±50 BP (1650–1890 CE) and 380±60 BP (1430–1650 CE). The dendrochronological date of the wood (after 1677) in the upper layer of the buried soil horizon in the in the Dombai section probably indicate the increase of the river runoff and debris flow activity in relation with the glacier advance in the upperstream of Ammanauz river. However it is also close to the Terskoye earth quake occurred in 1688. The radiocarbon dates of the buried soils cluster in three groups (270–290, 340–440, 1280–1440 yrs BP). It is possible that their burial is connected to the climatic (increase in precipitation, especially extreme ones) or seismic causes.В разрезе склоновых отложений р. Баксан и флювиогляциальных отложений р. Аманауз (пос. Домбай) радиоуглеродным и дендрохронологическим методами датированы горизонты погребённых почв. В разрезе «Баксан» выделяются три таких горизонта, в разрезе «Домбай» – один. Радиоуглеродный возраст двух наиболее выраженных горизонтов погребённых почв в верховьях долины р. Баксан составляет 170±50 л.н. (1650–1890 гг.) и 380±60 л.н. (1430–1650 гг.). Гибель дерева (дендрохронологическая датировка – после 1677 г.), захороненного в кровле погребённого почвенного горизонта в разрезе «Домбай», возможно, указывает на увеличение в это время объёма речного стока и селевой активности в связи с изменениями размеров ледников в верховьях р. Аманауз, однако не исключено и совпадение с Терским землетрясением 1688 г. Датировки погребённых почв в регионе объединяются в три группы: 270–290, 340–440 и 1280–1440 л.н. Возможны климатические (увеличение осадков, в том числе экстремальных) или сейсмические причины захоронения этих почвенных горизонтов

Возраст морен ледника Большой Азау в верховьях долины реки Баксан по дендрохронологическим данным

Basing on tree­ring analysis of more than 150pines growing in the Azau clearing, the minimum age of the deposits created by the Greater Azau Glacier was identified. Historical evidence, cartographic data, remote sensing materials, as well as the results of lichenometric studies and radiocarbon dating of buried soils were used as additional sources of information. We determined limits of the area covered by the glacier tongue at the end of the 19th century. It was also shown that the highest and most pronounced lateral moraine, conventionally called the «17th century moraine», was formed earlier than the end of the 15th century. Judging from the size of the maximum lichens of Rhizocarpon geographicum (120–130mm) on its surface, the age of the moraine, determined by the dendrochronological method was found to be underestimated. It may be several centuries older than the end of the 16th century. We re­examined a pine trunk buried in the sediments at the bottom of the valley which was discovered in the 1960s. Previously it was dated by radiocarbon (140±75BP[1], the calibrated date– 1650–1960 CE). According to the new data, the most probable tree­ring dates of the buried tree are 1759–1883CE, however, the second most likely dates are 1826–1950CE. Unfortunately, low statistical estimates do not allow us to confirm the reliability of the dates. The paper also discusses the controversial issue of the position of the moraine of 1849CE, which was described by H.Abich[2]. The annex to the article contains a translation of a fragment of this important paper related to the Greater Azau Glacier. Suppressions of pine growth from the moraines of the Greater Azau in the 1640s, 1710s, 1800s, 1840s, and 1860sCE are synchronous with the advances of the Bosson, Mer de Glace and Grindelwald glaciers in the Alps[3].На основе анализа дендрохронологических данных, радиоуглеродных датировок и исторических свидетельств рассмотрена история колебаний ледника Большой Азау в малый ледниковый период. Дискутируется вопрос о положении морены максимума наступания ледника в 1849г., описанного Г.Абихом. Определён минимальный возраст морен, в том числе береговой, которую ранее относили к XVII в

Изменения ледника Чалаати (Грузинский Кавказ) с малого ледникового периода по данным космогенных изотопов (10Be) и дендрохронологии

Glacier variations over the past centuries are still poorly documented on the southern slope of the Greater Caucasus. In this paper, the change of Chalaati Glacier in the Georgian Caucasus from its maximum extent during the Little Ice Age has been studied. For the first time in the history of glaciological studies of the Georgian Caucasus, 10Be in situ Cosmic Ray Exposure (CRE) dating was applied. The age of moraines was determined by tree-ring analysis. Lichenometry was also used as a supplementary tool to determine the relative ages of glacial landforms. In addition, the large-scale topographical maps (1887, 1960) were used along with the satellite imagery – Corona, Landsat 5 TM, and Sentinel 2B. Repeated photographs were used to identify the glacier extent in the late XIX and early XX centuries. 10Be CRE ages from the oldest lateral moraine of the Chalaati Glacier suggest that the onset of the Little Ice Age occurred ~0.73±0.04 kyr ago (CE ~1250–1330), while the dendrochronology and lichenometry measurements show that the Chalaati Glacier reached its secondary maximum extent again about CE ~1810. From that time through 2018 the glacier area decreased from 14.9±1.5 km2 to 9.9±0.5 km2 (33.8±7.4% or ~0.16% yr−1), while its length retreated by ~2280 m. The retreat rate was uneven: it peaked between 1940 and 1971 (~22.9 m yr−1), while the rate was slowest in 1910– 1930 (~4.0 m yr−1). The terminus elevation rose from ~1620 m to ~1980 m above sea level in ~1810–2018.Для реконструкции колебаний ледника Чалаати в Грузии использовались космические снимки, старые карты, повторные фотографии, дендрохронология, лихенометрия и анализ космогенных изотопов. Максимальное наступание ледника в начале малого ледникового периода произошло в ~1250–1330 гг., второй максимум, когда ледник достиг почти такой же длины, датируется примерно 1810 г. С этого времени до 2018 г. площадь ледника уменьшилась с 14,9±1,5 до 9,9±0,5 км2 (33,8±7,4%, или ~0,16% год−1), а его длина сократилась на ~2280 м

История ледника Донгуз-Орун по биоиндикационным, историческим, картографическим источникам и данным дистанционного зондирования

On 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

Arctic hydroclimate variability during the last 2000 years : current understanding and research challenges

Reanalysis data show an increasing trend in Arctic precipitation over the 20th century, but changes are not homogenous across seasons or space. The observed hydro-climate changes are expected to continue and possibly accelerate in the coming century, not only affecting pan-Arctic natural ecosystems and human activities, but also lower latitudes through the atmospheric and ocean circulations. However, a lack of spatiotemporal observational data makes reliable quantification of Arctic hydroclimate change difficult, especially in a long-term context. To understand Arctic hydroclimate and its variability prior to the instrumental record, climate proxy records are needed. The purpose of this review is to summarise the current understanding of Arctic hydroclimate during the past 2000 years. First, the paper reviews the main natural archives and proxies used to infer past hydroclimate variations in this remote region and outlines the difficulty of disentangling the moisture from the temperature signal in these records. Second, a comparison of two sets of hydroclimate records covering the Common Era from two data-rich regions, North America and Fennoscandia, reveals inter- and intra-regional differences. Third, building on earlier work, this paper shows the potential for providing a high-resolution hydroclimate reconstruction for the Arctic and a comparison with last-millennium simulations from fully coupled climate models. In general, hydroclimate proxies and simulations indicate that the Medieval Climate Anomaly tends to have been wetter than the Little Ice Age (LIA), but there are large regional differences. However, the regional coverage of the proxy data is inadequate, with distinct data gaps in most of Eurasia and parts of North America, making robust assessments for the whole Arctic impossible at present. To fully assess pan-Arctic hydroclimate variability for the last 2 millennia, additional proxy records are required.Peer reviewe

Реконструкция баланса массы ледника Гарабаши (1800–2005 гг.) по дендрохронологическим данным

The exploration whether tree-ring data can be effectually applied for the mass balance reconstruction in Caucasus was the main goal of this research. Tree-ring width and maximum density chronologies of pine (Pinus sylvestris L.) at seven high-elevation sites in Northern Caucasus were explored for this purpose. As well as in other places of the temperate zone tree- ring width has complex climate signal controlled both temperature and precipitation. Instrumental mass balance records of Garabashi Gglacier started at 1983s. It is well known that Caucasus glaciers intensively retreat in the last decades and according to instrumental data mass balance variations are mostly controlled by the ablation, i.e. summer temperature variations. Maximum density chronology has statistically significant correlation with mass balance due to summer temperature sensitivity and great input of ablation to total mass balance variations. To include in our reconstruction different climatically sensitive parameters, stepwise multiple regression model was used. The strongest relation (r = 0.88; r2 = 0.78; p < 0.05) between two ring-width and one maximum density chronologies was identified. Cross-validation test (r = 0.79; r2 = 0.62; p < 0.05) confirmed model adequacy and it allowed to reconstruct Garabashi Glacier mass balance for 1800–2005ss. Reconstructed and instrumental mass balance values coincide well except the most recent period in 2000s, when the reconstructed mass balance slightly underestimated the real values. However even in this period it remained negative as well as the instrumental records. The bias can be explained by the weak sensitivity of the chronologies to winter precipitation (i.e. accumulation). The tree-ring based mass balance reconstruction was compared with one based on meteorological data (since 1905s). Both reconstructions have good interannual agreement (r = 0.53; p < 0.05) particularly for the period between 1975 and 2005. According to the reconstruction two distinct periods of positive mass balance occurred in 1830s and 1860s. They agree well with early historical data and the tree-ring of moraines of Kashkatash Glacier in Central Caucasus. Выполнена первая реконструкции баланса массы ледника Гарабаши по дендрохронологическим данным с 1800 по 2005 г. Лучше всего модель воспроизводит изменчивость годового баланса ледника при использовании хронологий по ширине годичных колец и по максимальной плотности поздней древесины. Изучен вклад каждой древесно-кольцевой хронологии в модель и её климатический отклик. Установлена высокая согласованность реконструкции баланса массы ледника по дендрохронологическим данным с реконструкциями, полученными ранее по метеорологическим рядам