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  • 1
    In: Antarctic Science, Cambridge University Press (CUP), Vol. 33, No. 4 ( 2021-08), p. 418-427
    Abstract: The region of Ridge B in central East Antarctica is one of the last unexplored parts of the continent and, at the same time, ranks among the most promising places to search for Earth's oldest ice. In January 2020, we carried out the first scientific traverse from Russia's Vostok Station to the topographical dome of Ridge B (Dome B, 3807 m above sea level, 79.02°S, 93.69°E). The glaciological programme included continuous snow-radar profiling and geodetic positioning along the traverse's route, installation of snow stakes, measurements of snow density, collection of samples for stable water isotope and chemical analyses and drilling of a 20 m firn core. The first results of the traverse show that the surface mass balance at Dome B (2.28 g cm −2 year −1 ) is among the lowest in Antarctica. The firn temperature below the layer of annual variations is −58.1 ± 0.2°C. A very low value of heavy water stable isotope content (-58.2‰ for oxygen-18) was discovered at a distance of 170 km from Vostok Station. This work is the first step towards a comprehensive reconnaissance study of the Ridge B area aimed at locating the best site for future deep drilling for the oldest Antarctic ice.
    Type of Medium: Online Resource
    ISSN: 0954-1020 , 1365-2079
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2021
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  • 2
    Online Resource
    Online Resource
    Geological Society of London ; 2018
    In:  Geological Society, London, Special Publications Vol. 461, No. 1 ( 2018-01), p. 187-196
    In: Geological Society, London, Special Publications, Geological Society of London, Vol. 461, No. 1 ( 2018-01), p. 187-196
    Type of Medium: Online Resource
    ISSN: 0305-8719 , 2041-4927
    Language: English
    Publisher: Geological Society of London
    Publication Date: 2018
    detail.hit.zdb_id: 2478172-1
    detail.hit.zdb_id: 196249-8
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  • 3
    In: Journal of Geophysical Research: Earth Surface, American Geophysical Union (AGU), Vol. 119, No. 11 ( 2014-11), p. 2460-2480
    Abstract: Ice surface height above Lake Vostok has been stable between 2001 and 2013 Water volume in subglacial Lake Vostok has remained unchanged over a decade Surface and marker height changes are derived with accuracies better than 1 cm/a
    Type of Medium: Online Resource
    ISSN: 2169-9003 , 2169-9011
    URL: Issue
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2014
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    detail.hit.zdb_id: 2138320-0
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  • 4
    In: Frontiers in Earth Science, Frontiers Media SA, Vol. 11 ( 2023-1-25)
    Abstract: Introduction: The products of volcanic eruptions found in the snow, firn and ice deposits of the polar ice sheets are precious sources of information on the volcanic forcing of the climate system in the recent or remote past. On the other hand, the layers containing the traces of well-known eruptions serve as absolute age markers that help to construct the depth-age scale for the snow-firn thickness. Methods: In this study we present new records of the sulfate concentrations and electrical conductivity (ECM) from three shallow (up to 70 m depth) firn cores drilled in the vicinity of Vostok station (central East Antarctica). Results: In the non-sea-salt sulfate and ECM profiles we were able to identify 68 peaks that can be interpreted as traces of volcanic events. Discussion: 22 of these peaks can be unambiguously attributed to well-known volcanic eruptions (including Tambora 1816 CE, Huaynaputina 1601 CE, Samalas 1258 CE, Ilopango 541 CE and others), which allowed to construct a robust depth-age scale for the cores. 37 events have their counterparts in other Antarctic cores, but cannot be associated with welldated eruptions. Finally, 9 peaks do not have analogues in the other cores, i.e., they may be traces of so far unknown volcanic events. According to the newly constructed depth-age function, the deepest studied firn layers (70.20 m) are dated by 192 BCE.
    Type of Medium: Online Resource
    ISSN: 2296-6463
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2023
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  • 5
    In: Annals of Glaciology, Cambridge University Press (CUP), Vol. 62, No. 85-86 ( 2021-09), p. 305-310
    Abstract: Recent studies have shown that stratigraphically disturbed meteoric ice bedded at Vostok Station between 3318 and 3539 m dates back to 1.2 Ma BP and possibly beyond. As part of the VOICE (Vostok Oldest Ice Challenge) initiative, a new deviation from parent hole 5G-1 was made at depths of 3270–3291 m in the 2018/19 austral season with the aim of obtaining a replicate core of the old ice. Sidetracking was initiated using the standard KEMS-132 electromechanical drill routinely employed for deep ice coring at Vostok, without significant changes to its initial design. Here we describe the method and operating procedures for replicate coring at a targeted depth in an existing slant hole, involving the use of a cable-suspended electromechanical drill. The design of the milling cutter head used for sidetracking is presented. The performance characteristics and the experience of drilling branch-hole 5G-5 at Vostok are described and discussed.
    Type of Medium: Online Resource
    ISSN: 0260-3055 , 1727-5644
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2021
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  • 6
    Online Resource
    Online Resource
    Copernicus GmbH ; 2016
    In:  The Cryosphere Vol. 10, No. 3 ( 2016-06-07), p. 1217-1227
    In: The Cryosphere, Copernicus GmbH, Vol. 10, No. 3 ( 2016-06-07), p. 1217-1227
    Abstract: Abstract. We present the results of glaciological investigations in the megadune area located 30 km to the east of Vostok Station (central East Antarctica) implemented during the 58th, 59th and 60th Russian Antarctic Expedition (January 2013–2015). Snow accumulation rate and isotope content (δD, δ18O and δ17O) were measured along the 2 km profile across the megadune ridge accompanied by precise GPS altitude measurements and ground penetrating radar (GPR) survey. It is shown that the spatial variability of snow accumulation and isotope content covaries with the surface slope. The accumulation rate regularly changes by 1 order of magnitude within the distance 〈 1 km, with the reduced accumulation at the leeward slope of the dune and increased accumulation in the hollow between the dunes. At the same time, the accumulation rate averaged over the length of a dune wave (22 mm w.e.) corresponds well with the value obtained at Vostok Station, which suggests no additional wind-driven snow sublimation in the megadunes compared to the surrounding plateau. The snow isotopic composition is in negative correlation with the snow accumulation. Analysing dxs ∕ δD and 17O-excess ∕ δD slopes (where dxs  =  δD − 8 ⋅ δ18O and 17O-excess  =  ln(δ17O  ∕  1000 +  1) −0.528 ⋅ ln (δ18O ∕ 1000 + 1)), we conclude that the spatial variability of the snow isotopic composition in the megadune area could be explained by post-depositional snow modifications. Using the GPR data, we estimated the apparent dune drift velocity (4.6 ± 1.1 m yr−1). The full cycle of the dune drift is thus about 410 years. Since the spatial anomalies of snow accumulation and isotopic composition are supposed to drift with the dune, a core drilled in the megadune area would exhibit the non-climatic 410-year cycle of these two parameters. We simulated a vertical profile of snow isotopic composition with such a non-climatic variability, using the data on the dune size and velocity. This artificial profile is then compared with the real vertical profile of snow isotopic composition obtained from a core drilled in the megadune area. We note that the two profiles are very similar. The obtained results are discussed in terms of interpretation of data obtained from ice cores drilled beyond the megadune areas.
    Type of Medium: Online Resource
    ISSN: 1994-0424
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2016
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  • 7
    In: Environmental Earth Sciences, Springer Science and Business Media LLC, Vol. 75, No. 23 ( 2016-12)
    Type of Medium: Online Resource
    ISSN: 1866-6280 , 1866-6299
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2016
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  • 8
    In: Climate of the Past, Copernicus GmbH, Vol. 13, No. 11 ( 2017-11-17), p. 1609-1634
    Abstract: Abstract. Climate trends in the Antarctic region remain poorly characterized, owing to the brevity and scarcity of direct climate observations and the large magnitude of interannual to decadal-scale climate variability. Here, within the framework of the PAGES Antarctica2k working group, we build an enlarged database of ice core water stable isotope records from Antarctica, consisting of 112 records. We produce both unweighted and weighted isotopic (δ18O) composites and temperature reconstructions since 0 CE, binned at 5- and 10-year resolution, for seven climatically distinct regions covering the Antarctic continent. Following earlier work of the Antarctica2k working group, we also produce composites and reconstructions for the broader regions of East Antarctica, West Antarctica and the whole continent. We use three methods for our temperature reconstructions: (i) a temperature scaling based on the δ18O–temperature relationship output from an ECHAM5-wiso model simulation nudged to ERA-Interim atmospheric reanalyses from 1979 to 2013, and adjusted for the West Antarctic Ice Sheet region to borehole temperature data, (ii) a temperature scaling of the isotopic normalized anomalies to the variance of the regional reanalysis temperature and (iii) a composite-plus-scaling approach used in a previous continent-scale reconstruction of Antarctic temperature since 1 CE but applied to the new Antarctic ice core database. Our new reconstructions confirm a significant cooling trend from 0 to 1900 CE across all Antarctic regions where records extend back into the 1st millennium, with the exception of the Wilkes Land coast and Weddell Sea coast regions. Within this long-term cooling trend from 0 to 1900 CE, we find that the warmest period occurs between 300 and 1000 CE, and the coldest interval occurs from 1200 to 1900 CE. Since 1900 CE, significant warming trends are identified for the West Antarctic Ice Sheet, the Dronning Maud Land coast and the Antarctic Peninsula regions, and these trends are robust across the distribution of records that contribute to the unweighted isotopic composites and also significant in the weighted temperature reconstructions. Only for the Antarctic Peninsula is this most recent century-scale trend unusual in the context of natural variability over the last 2000 years. However, projected warming of the Antarctic continent during the 21st century may soon see significant and unusual warming develop across other parts of the Antarctic continent. The extended Antarctica2k ice core isotope database developed by this working group opens up many avenues for developing a deeper understanding of the response of Antarctic climate to natural and anthropogenic climate forcings. The first long-term quantification of regional climate in Antarctica presented herein is a basis for data–model comparison and assessments of past, present and future driving factors of Antarctic climate.
    Type of Medium: Online Resource
    ISSN: 1814-9332
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2017
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  • 9
    In: Earth System Science Data, Copernicus GmbH, Vol. 11, No. 3 ( 2019-09-30), p. 1463-1481
    Abstract: Abstract. This study presents a dataset on long-term multidisciplinary glaciological, hydrological, and meteorological observations and isotope sampling in a sparsely monitored alpine zone of the North Caucasus in the Djankuat research basin. The Djankuat glacier, which is the largest in the basin, was chosen as representative of the central North Caucasus during the International Hydrological Decade and is one of 30 “reference” glaciers in the world that have annual mass balance series longer than 50 years (Zemp et al., 2009). The dataset features a comprehensive set of observations from 2007 to 2017 and contains yearly measurements of snow depth and density; measurements of dynamics of snow and ice melting; measurements of water runoff, conductivity, turbidity, temperature, δ18O, δD at the main gauging station (844 samples in total) with an hourly or sub-daily time step depending on the parameter; data on δ18O and δ2H sampling of liquid precipitation, snow, ice, firn, and groundwater in different parts of the watershed taken regularly during melting season (485 samples in total); measurements of precipitation amount, air temperature, relative humidity, shortwave incoming and reflected radiation, longwave downward and upward radiation, atmospheric pressure, and wind speed and direction – measured at several automatic weather stations within the basin with 15 min to 1 h time steps; gradient meteorological measurements to estimate turbulent fluxes of heat and moisture, measuring three components of wind speed at a frequency of 10 Hz to estimate the impulse of turbulent fluxes of sensible and latent heat over the glacier surface by the eddy covariance method. Data were collected during the ablation period (June–September). The observations were halted in winter. The dataset is available from PANGAEA (https://doi.org/10.1594/PANGAEA.894807, Rets et al., 2018a) and will be further updated. The dataset can be useful for developing and verifying hydrological, glaciological, and meteorological models for alpine areas, to study the impact of climate change on hydrology of mountain regions using isotopic and hydrochemical approaches in hydrology. As the dataset includes the measurements of hydrometeorological and glaciological variables during the catastrophic proglacial lake outburst in the neighboring Bashkara valley in September 2017, it is a valuable contribution to study lake outbursts.
    Type of Medium: Online Resource
    ISSN: 1866-3516
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2019
    detail.hit.zdb_id: 2475469-9
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  • 10
    In: The Cryosphere, Copernicus GmbH, Vol. 10, No. 2 ( 2016-04-15), p. 837-852
    Abstract: Abstract. The isotopic compositions of oxygen and hydrogen in ice cores are invaluable tools for the reconstruction of past climate variations. Used alone, they give insights into the variations of the local temperature, whereas taken together they can provide information on the climatic conditions at the point of origin of the moisture. However, recent analyses of snow from shallow pits indicate that the climatic signal can become erased in very low accumulation regions, due to local processes of snow reworking. The signal-to-noise ratio decreases and the climatic signal can then only be retrieved using stacks of several snow pits. Obviously, the signal is not completely lost at this stage, otherwise it would be impossible to extract valuable climate information from ice cores as has been done, for instance, for the last glaciation. To better understand how the climatic signal is passed from the precipitation to the snow, we present here results from varied snow samples from East Antarctica. First, we look at the relationship between isotopes and temperature from a geographical point of view, using results from three traverses across Antarctica, to see how the relationship is built up through the distillation process. We also take advantage of these measures to see how second-order parameters (d-excess and 17O-excess) are related to δ18O and how they are controlled. d-excess increases in the interior of the continent (i.e., when δ18O decreases), due to the distillation process, whereas 17O-excess decreases in remote areas, due to kinetic fractionation at low temperature. In both cases, these changes are associated with the loss of original information regarding the source. Then, we look at the same relationships in precipitation samples collected over 1 year at Dome C and Vostok, as well as in surface snow at Dome C. We note that the slope of the δ18O vs. temperature (T) relationship decreases in these samples compared to those from the traverses, and thus caution is advocated when using spatial slopes for past climate reconstruction. The second-order parameters behave in the same way in the precipitation as in the surface snow from traverses, indicating that similar processes are active and that their interpretation in terms of source climatic parameters is strongly complicated by local temperature effects in East Antarctica. Finally we check if the same relationships between δ18O and second-order parameters are also found in the snow from four snow pits. While the d-excess remains opposed to δ18O in most snow pits, the 17O-excess is no longer positively correlated to δ18O and even shows anti-correlation to δ18O at Vostok. This may be due to a stratospheric influence at this site and/or to post-deposition processes.
    Type of Medium: Online Resource
    ISSN: 1994-0424
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2016
    detail.hit.zdb_id: 2393169-3
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