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1. Geochemical signatures of pingo ice and its origin in Grøndalen, west Spitsbergen

Author

N. Demidov, S. Wetterich, S. Verkulich, A. Ekaykin, H. Meyer, M. Anisimov, L. Schirrmeister, V. Demidov, and A. J. Hodson

Subjects
Environmental sciences, GE1-350, Geology, QE1-996.5
Abstract

Pingos are common features in permafrost regions that form by subsurface massive-ice aggradation and create hill-like landforms. Pingos on Spitsbergen have been previously studied to explore their structure, formation timing and connection to springs as well as their role in postglacial landform evolution. However, detailed hydrochemical and stable-isotope studies of massive-ice samples recovered by drilling have yet to be used to study the origin and freezing conditions in pingos. Our core record of 20.7 m thick massive pingo ice from Grøndalen is differentiated into four units: two characterised by decreasing δ18O and δD and increasing d (units I and III) and two others showing the opposite trend (units II and IV). These delineate changes between episodes of closed-system freezing with only slight recharge inversions of the water reservoir and more complicated episodes of groundwater freezing under semi-closed conditions when the reservoir was recharged. The water source for pingo formation shows similarity to spring water data from the valley with prevalent Na+ and HCO3- ions. The sub-permafrost groundwater originates from subglacial meltwater that most probably followed the fault structures of Grøndalen and Bøhmdalen. The presence of permafrost below the pingo ice body suggests that the talik is frozen, and the water supply and pingo growth are terminated. The maximum thaw depth of the active layer reaching the top of the massive ice leads to its successive melt with crater development and makes the pingo extremely sensitive to further warming.

Published
2019
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2. Archival processes of the water stable isotope signal in East Antarctic ice cores

Author

M. Casado, A. Landais, G. Picard, T. Münch, T. Laepple, B. Stenni, G. Dreossi, A. Ekaykin, L. Arnaud, C. Genthon, A. Touzeau, V. Masson-Delmotte, and J. Jouzel

Subjects
Environmental sciences, GE1-350, Geology, QE1-996.5
Abstract

The oldest ice core records are obtained from the East Antarctic Plateau. Water isotopes are key proxies to reconstructing past climatic conditions over the ice sheet and at the evaporation source. The accuracy of climate reconstructions depends on knowledge of all processes affecting water vapour, precipitation and snow isotopic compositions. Fractionation processes are well understood and can be integrated in trajectory-based Rayleigh distillation and isotope-enabled climate models. However, a quantitative understanding of processes potentially altering snow isotopic composition after deposition is still missing. In low-accumulation sites, such as those found in East Antarctica, these poorly constrained processes are likely to play a significant role and limit the interpretability of an ice core's isotopic composition.By combining observations of isotopic composition in vapour, precipitation, surface snow and buried snow from Dome C, a deep ice core site on the East Antarctic Plateau, we found indications of a seasonal impact of metamorphism on the surface snow isotopic signal when compared to the initial precipitation. Particularly in summer, exchanges of water molecules between vapour and snow are driven by the diurnal sublimation–condensation cycles. Overall, we observe in between precipitation events modification of the surface snow isotopic composition. Using high-resolution water isotopic composition profiles from snow pits at five Antarctic sites with different accumulation rates, we identified common patterns which cannot be attributed to the seasonal variability of precipitation. These differences in the precipitation, surface snow and buried snow isotopic composition provide evidence of post-deposition processes affecting ice core records in low-accumulation areas.

Published
2018
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3. Antarctic climate variability on regional and continental scales over the last 2000 years

Author

B. Stenni, M. A. J. Curran, N. J. Abram, A. Orsi, S. Goursaud, V. Masson-Delmotte, R. Neukom, H. Goosse, D. Divine, T. van Ommen, E. J. Steig, D. A. Dixon, E. R. Thomas, N. A. N. Bertler, E. Isaksson, A. Ekaykin, M. Werner, and M. Frezzotti

Subjects
Environmental pollution, TD172-193.5, Environmental protection, TD169-171.8, Environmental sciences, GE1-350
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.

Published
2017
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4. Large-scale drivers of Caucasus climate variability in meteorological records and Mt El'brus ice cores

Author

A. Kozachek, V. Mikhalenko, V. Masson-Delmotte, A. Ekaykin, P. Ginot, S. Kutuzov, M. Legrand, V. Lipenkov, and S. Preunkert

Subjects
Environmental pollution, TD172-193.5, Environmental protection, TD169-171.8, Environmental sciences, GE1-350
Abstract

A 181.8 m ice core was recovered from a borehole drilled into bedrock on the western plateau of Mt El'brus (43°20′53.9′′ N, 42°25′36.0′′ E; 5115 m a.s.l.) in the Caucasus, Russia, in 2009 (Mikhalenko et al., 2015). Here, we report on the results of the water stable isotope composition from this ice core with additional data from the shallow cores. The distinct seasonal cycle of the isotopic composition allows dating by annual layer counting. Dating has been performed for the upper 126 m of the deep core combined with 20 m from the shallow cores. The whole record covers 100 years, from 2013 back to 1914. Due to the high accumulation rate (1380 mm w.e. year−1) and limited melting, we obtained isotopic composition and accumulation rate records with seasonal resolution. These values were compared with available meteorological data from 13 weather stations in the region and also with atmosphere circulation indices, back-trajectory calculations, and Global Network of Isotopes in Precipitation (GNIP) data in order to decipher the drivers of accumulation and ice core isotopic composition in the Caucasus region. In the warm season (May–October) the isotopic composition depends on local temperatures, but the correlation is not persistent over time, while in the cold season (November–April), atmospheric circulation is the predominant driver of the ice core's isotopic composition. The snow accumulation rate correlates well with the precipitation rate in the region all year round, which made it possible to reconstruct and expand the precipitation record at the Caucasus highlands from 1914 until 1966, when reliable meteorological observations of precipitation at high elevation began.

Published
2017
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5. Non-climatic signal in ice core records: lessons from Antarctic megadunes

Author

A. Ekaykin, L. Eberlein, V. Lipenkov, S. Popov, M. Scheinert, L. Schröder, and A. Turkeev

Subjects
Environmental sciences, GE1-350, Geology, QE1-996.5
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 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.

Published
2016
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6. Acquisition of isotopic composition for surface snow in East Antarctica and the links to climatic parameters

Author

A. Touzeau, A. Landais, B. Stenni, R. Uemura, K. Fukui, S. Fujita, S. Guilbaud, A. Ekaykin, M. Casado, E. Barkan, B. Luz, O. Magand, G. Teste, E. Le Meur, M. Baroni, J. Savarino, I. Bourgeois, and C. Risi

Subjects
Environmental sciences, GE1-350, Geology, QE1-996.5
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.

Published
2016
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7. Investigation of a deep ice core from the Elbrus western plateau, the Caucasus, Russia

Author

V. Mikhalenko, S. Sokratov, S. Kutuzov, P. Ginot, M. Legrand, S. Preunkert, I. Lavrentiev, A. Kozachek, A. Ekaykin, X. Faïn, S. Lim, U. Schotterer, V. Lipenkov, and P. Toropov

Subjects
Environmental sciences, GE1-350, Geology, QE1-996.5
Abstract

A 182 m ice core was recovered from a borehole drilled into bedrock on the western plateau of Mt. Elbrus (43°20´53.9'' N, 42°25´36.0'' E; 5115 m a.s.l.) in the Caucasus, Russia, in 2009. This is the first ice core in the region that represents a paleoclimate record that is practically undisturbed by seasonal melting. Relatively high snow accumulation rates at the drilling site enabled the analysis of the intraseasonal variability in climate proxies. Borehole temperatures ranged from −17 °C at 10 m depth to −2.4 °C at 182 m. A detailed radio-echo sounding survey showed that the glacier thickness ranged from 45 m near the marginal zone of the plateau up to 255 m at the glacier center. The ice core has been analyzed for stable isotopes (δ18O and δD), major ions (K+, Na+, Ca2+, Mg2+, NH4+, SO42-, NO3-, Cl-, F-), succinic acid (HOOCCH2COOH), and tritium content. The mean annual net accumulation rate of 1455 mm w.e. for the last 140 years was estimated from distinct annual oscillations of δ18O, δD, succinic acid, and NH4+. Annual layer counting also helped date the ice core, agreeing with the absolute markers of the tritium 1963 bomb horizon located at the core depth of 50.7 m w.e. and the sulfate peak of the Katmai eruption (1912) at 87.7 m w.e. According to mathematical modeling results, the ice age at the maximum glacier depth is predicted to be ~ 660 years BP. The 2009 borehole is located downstream from this point, resulting in an estimated basal ice age of less than 350–400 years BP at the drilling site. The glaciological and initial chemical analyses from the Elbrus ice core help reconstruct the atmospheric history of the European region.

Published
2015
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9. A comparison of the present and last interglacial periods in six Antarctic ice cores

Author

V. Masson-Delmotte, D. Buiron, A. Ekaykin, M. Frezzotti, H. Gallée, J. Jouzel, G. Krinner, A. Landais, H. Motoyama, H. Oerter, K. Pol, D. Pollard, C. Ritz, E. Schlosser, L. C. Sime, H. Sodemann, B. Stenni, R. Uemura, and F. Vimeux

Subjects
Environmental pollution, TD172-193.5, Environmental protection, TD169-171.8, Environmental sciences, GE1-350
Abstract

We compare the present and last interglacial periods as recorded in Antarctic water stable isotope records now available at various temporal resolutions from six East Antarctic ice cores: Vostok, Taylor Dome, EPICA Dome C (EDC), EPICA Dronning Maud Land (EDML), Dome Fuji and the recent TALDICE ice core from Talos Dome. We first review the different modern site characteristics in terms of ice flow, meteorological conditions, precipitation intermittency and moisture origin, as depicted by meteorological data, atmospheric reanalyses and Lagrangian moisture source diagnostics. These different factors can indeed alter the relationships between temperature and water stable isotopes. Using five records with sufficient resolution on the EDC3 age scale, common features are quantified through principal component analyses. Consistent with instrumental records and atmospheric model results, the ice core data depict rather coherent and homogenous patterns in East Antarctica during the last two interglacials. Across the East Antarctic plateau, regional differences, with respect to the common East Antarctic signal, appear to have similar patterns during the current and last interglacials. We identify two abrupt shifts in isotopic records during the glacial inception at TALDICE and EDML, likely caused by regional sea ice expansion. These regional differences are discussed in terms of moisture origin and in terms of past changes in local elevation histories, which are compared to ice sheet model results. Our results suggest that elevation changes may contribute significantly to inter-site differences. These elevation changes may be underestimated by current ice sheet models.

Published
2011
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10. Recent increase in the surface mass balance in central East Antarctica is unprecedented for the last 2000 years

Author

Alexey A. Ekaykin, Arina N. Veres, and Yetang Wang

Subjects
Geology, QE1-996.5, Environmental sciences, GE1-350
Abstract

Abstract The Antarctic Ice Sheet’s reaction on the continuing global warming is crucial to project the future sea level rise. The increasing air temperature causes both accelerating mass loss on the Antarctica’s margins and increased surface mass balance in its interior. Here, we use data from firn cores drilled near Vostok station (central East Antarctica) to analyze the surface mass balance variability over the past 2200 years. We show a 24% increase of snow accumulation rate since early 19 century confirmed by the instrumental data for the last 52 years. The mean surface mass balance value in 1970–2021 (2.25 ± 0.064 g cm−2 yr−1) is very likely unprecedented in the pre-industrial era. The surface mass balance growth is accompanied by the air temperature increase with the sensitivity of 11 ± 2% per 1 °C. These results will help to constrain the potential magnitude of Antarctic snowfall mitigation of future sea level rise.

Published
2024
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14. Ice core chemistry database: an Antarctic compilation of sodium and sulfate records spanning the past 2000 years

Author

E. R. Thomas, D. O. Vladimirova, D. R. Tetzner, B. D. Emanuelsson, N. Chellman, D. A. Dixon, H. Goosse, M. M. Grieman, A. C. F. King, M. Sigl, D. G. Udy, T. R. Vance, D. A. Winski, V. H. L. Winton, N. A. N. Bertler, A. Hori, C. M. Laluraj, J. R. McConnell, Y. Motizuki, K. Takahashi, H. Motoyama, Y. Nakai, F. Schwanck, J. C. Simões, F. G. L. Lindau, M. Severi, R. Traversi, S. Wauthy, C. Xiao, J. Yang, E. Mosely-Thompson, T. V. Khodzher, L. P. Golobokova, and A. A. Ekaykin

Subjects
Environmental sciences, GE1-350, Geology, QE1-996.5
Abstract

Changes in sea ice conditions and atmospheric circulation over the Southern Ocean play an important role in modulating Antarctic climate. However, observations of both sea ice and wind conditions are limited in Antarctica and the Southern Ocean, both temporally and spatially, prior to the satellite era (1970 onwards). Ice core chemistry data can be used to reconstruct changes over annual, decadal, and millennial timescales. To facilitate sea ice and wind reconstructions, the CLIVASH2k (CLimate Variability in Antarctica and the Southern Hemisphere over the past 2000 years) working group has compiled a database of two species, sodium [Na+] and sulfate [SO42-], commonly measured ionic species. The database (https://doi.org/10.5285/9E0ED16E-F2AB-4372-8DF3-FDE7E388C9A7; Thomas et al., 2022) comprises records from 105 Antarctic ice cores, containing records with a maximum age duration of 2000 years. An initial filter has been applied, based on evaluation against sea ice concentration, geopotential height (500 hPa), and surface wind fields to identify sites suitable for reconstructing past sea ice conditions, wind strength, or atmospheric circulation.

Published
2023
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15. A record of volcanic eruptions over the past 2,200 years from Vostok firn cores, central East Antarctica

Author

Arina N. Veres, Alexey A. Ekaykin, Liudmila P. Golobokova, Tamara V. Khodzher, Olga I. Khuriganowa, and Alexey V. Turkeev

Subjects
volcanic inventory, Vostok station, Late Holocene, firn core, East Antarctica, non-sea-salt sulfates, Science
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.

Published
2023
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16. Drilling the new 5G-5 branch hole at Vostok Station for collecting a replicate core of old meteoric ice

Author

Aleksei V. Turkeev, Nikolai I. Vasilev, Vladimir Ya. Lipenkov, Alexey V. Bolshunov, Alexey A. Ekaykin, Andrei N. Dmitriev, and Dmitrii A. Vasilev

Subjects
Ice drilling, old ice, paleoclimate, replicate ice coring, sidetracking, Meteorology. Climatology, QC851-999
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.

Published
2021
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19. Surface Mass Balance Models Vs. Stake Observations: A Comparison in the Lake Vostok Region, Central East Antarctica

Author

Andreas Richter, Alexey A. Ekaykin, Matthias O. Willen, Vladimir Ya. Lipenkov, Andreas Groh, Sergey V. Popov, Mirko Scheinert, Martin Horwath, and Reinhard Dietrich

Subjects
surface mass balance, stake observations, regional climate models, Antarctica, Vostok, Science
Abstract

The surface mass balance (SMB) is very low over the vast East Antarctic Plateau, for example in the Vostok region, where the mean SMB is on the order of 20–35 kg m-2 a-1. The observation and modeling of spatio-temporal SMB variations are equally challenging in this environment. Stake measurements carried out in the Vostok region provide SMB observations over half a century (1970–2019). This unique data set is compared with SMB estimations of the regional climate models RACMO2.3p2 (RACMO) and MAR3.11 (MAR). We focus on the SMB variations over time scales from months to decades. The comparison requires a rigorous assessment of the uncertainty in the stake observations and the spatial scale dependence of the temporal SMB variations. Our results show that RACMO estimates of annual and multi-year SMB agree well with the observations. The regression slope between modelled and observed temporal variations is close to 1.0 for this model. SMB simulations by MAR are affected by a positive bias which amounts to 6 kg m-2 a-1 at Vostok station and 2 kg m-2 a-1 along two stake profiles between Lake Vostok and Ridge B. None of the models is capable to reproduce the seasonal distributions of SMB and precipitation. Model SMB estimates are used in assessing the ice-mass balance and sea-level contribution of the Antarctic Ice Sheet by the input-output method. Our results provide insights into the uncertainty contribution of the SMB models to such assessments.

Published
2021
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23. Stable isotope (δ18O, δ2H) signature of river runoff, groundwater and precipitation in three river basins in the center of East European Plain

Author

Julia Chizhova, Maria Kireeva, Ekaterina Rets, Alexey Ekaykin, Anna Kozachek, Arina Veres, Olga Zolina, Natalia Varentsova, Artem Gorbarenko, Nikita Povalyaev, Valentina Plotnikova, Timofey Samsonov, and Maxim Kharlamov

Abstract

Empirical study of the isotopic features of river runoff were conducted at three hydrological posts in three different river basins: the Zakza river in the center of East European Plane (southwest of Moscow), the Dubna river (north of Moscow) and the Sosna Bystraya river in the south of central region. Samples of river water, groundwater, and precipitation for the October 2019–October 2021 were collected at weekly intervals. At total 332 samples of river water, 275 samples of groundwater and 194 samples of precipitation were collected. Precipitation was collected as an integral sample of all precipitation fallen during the week before sampling date. For each precipitation samples, the total amount of precipitation and air temperature, weighted by precipitation amount, are given according to weather station in river basin. During the observation period, there were two completely different conditions in terms of runoff formation. First, from October 2019 to October 2020, there was an unusually low spring freshet followed by a big rain flood in July. From October 2020–October 2021, there was a normal intra-annual flow pattern with high spring freshet. A significant supply of melted snow during spring freshet is the key factor influencing water regimes in these three river basins; varying degrees of anthropogenic flow regulation are also present. The new height frequency and complete data of stable isotope signature of river runoff component can help to study the response of a river runoff to climate change.

Published
2022

27. A Review of Antarctic Surface Snow Isotopic Composition : Observations, Atmospheric Circulation, and Isotopic Modeling

Author

Masson-Delmotte, V., Hou, S., Ekaykin, A., Jouzel, J., Aristarain, A., Bernardo, R. T., Bromwich, D., Cattani, O., Delmotte, M., Falourd, S., Frezzotti, M., Gallée, H., Genoni, L., Isaksson, E., Landais, A., Helsen, M. M., Hoffmann, G., Lopez, J., Morgan, V., Motoyama, H., Noone, D., Oerter, H., Petit, J. R., Royer, A., Uemura, R., Schmidt, G. A., Schlosser, E., Simões, J. C., Steig, E. J., Stenni, B., Stievenard, M., van den Broeke, M. R., van de Wal, R. S. W., van de Berg, W. J., Vimeux, F., and White, J. W. C.

Published
2008

28. The Ant-Iso dataset: a compilation of Antarctic surface snow isotopic observations.

Author

Jiajia Wang, Hongxi Pang, Shuangye Wu, Schoenemann, Spruce W., Ryu Uemura, Ekaykin, Alexey, Werner, Martin, Cauquoin, Alexandre, Oger, Sentia Goursaud, Rupper, Summer, and Shugui Hou

Subjects
ICE cores, GENERAL circulation model, WATER distribution, ANTARCTIC ice, OXYGEN isotopes, ATMOSPHERIC circulation, CLIMATE sensitivity, ATMOSPHERIC models
Abstract

Stable water isotopic observations in surface snow over Antarctica provide a foundation for validating isotopic models and interpreting Antarctic ice core records. Here, we present a new compilation of Antarctic surface snow isotopic dataset with strict quality control from published and unpublished sources including measurements from snow pits, snow cores, ice cores, deep surface snow, and precipitation (multi-year average values). The dataset contains a total of 1867 data points, including 1604 locations for oxygen isotope ratio (d18O) and 1278 locations for deuterium isotope ratio (d2H). 1204 locations have both d18O and d2H, from which d-excess (d-excess = d2H - 8 × d18O) can be calculated. The dataset also contains geographic and climate information. The database has a wide range of potential applications, such as the study of the spatial distribution of water isotopes in Antarctica, the evaluation of climate models, and the reconstruction and interpretation of Antarctic ice core records. As an example of model evaluation, the compiled isotopic dataset is used to assess the performance of isotope-enabled atmospheric general circulation models (AGCMs) on simulating the spatial distribution of water isotopes over Antarctica. This dataset is the most comprehensive compilation so far of observed water isotope records at multi-year average scale from multiple sources for Antarctica. It is available for download at https://doi.org/10.5281/zenodo.7294183 (Wang et al., 2022). [ABSTRACT FROM AUTHOR]

Published
2022
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29. Stable isotope (d18O, d²H) signature of river runoff, groundwater, and precipitation in three river basins in the center of East European Plain.

Author

Chizhova, Julia, Kireeva, Maria, Rets, Ekaterina, Ekaykin, Alexey, Kozachek, Anna, Veres, Arina, Zolina, Olga, Varentsova, Natalia, Gorbarenko, Artem, Povalyaev, Nikita, Plotnikova, Valentina, Samsonov, Timofey, and Kharlamov, Maxim

Subjects
STABLE isotopes, RUNOFF, METEOROLOGICAL stations, ATMOSPHERIC temperature, SPRING, WATERSHEDS
Abstract

Empirical study of the isotopic features of river runoff were conducted at three hydrological posts in three different river basins: the Zakza river in the center of East European Plane (southwest of Moscow), the Dubna river (north of Moscow) and the Sosna Bystraya river in the south of central region. Samples of river water, groundwater, and precipitation for the October 2019 - October 2021 were collected at weekly intervals. At total 332 samples of river water, 275 samples of groundwater and 194 samples of precipitation were collected. Precipitation was collected as an integral sample of all precipitation fallen during the week before sampling date. For each precipitation samples, the total amount of precipitation and air temperature, weighted by precipitation amount, are given according to weather station in river basin. During the observation period, there were two completely different conditions in terms of runoff formation. First, from October 2019 to October 2020, there was an unusually low spring freshet followed by a big rain flood in July. From October 2020 - October 2021, there was a normal intra-annual flow pattern with high spring freshet. A significant supply of melted snow during spring freshet is the key factor influencing water regimes in these three river basins; varying degrees of anthropogenic flow regulation are also present. The new height frequency and complete data of stable isotope signature of river runoff component can help to study the response of a river runoff to climate change. [ABSTRACT FROM AUTHOR]

Published
2022
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30. Stable isotope (δ18O, δ²H) signature of river runoff, groundwater and precipitation in three river basins in the center of East European Plain.

Author

Chizhova, Julia, Kireeva, Maria, Rets, Ekaterina, Ekaykin, Alexey, Kozachek, Anna, Veres, Arina, Zolina, Olga, Varentsova, Natalia, Gorbarenko, Artem, Povalyaev, Nikita, Plotnikova, Valentina, Samsonov, Timofey, and Kharlamov, Maxim

Subjects
STABLE isotopes, RUNOFF, GROUNDWATER, WATER sampling, CLIMATE change
Abstract

Empirical study of the isotopic features of river runoff were carried out at three hydrological posts in 3 different river basins: the Zakza river in the center of East European Plane (southwest of the Moscow), the Dubna river (north of the Moscow) and the Sosna river in the south of central region. Samples of river water, groundwater and precipitation for the October 2019 - October 2021 were collected at weekly intervals. A significant supply of melted snow during spring freshet is the key factor influencing water regimes for these three river basins; varying degrees of anthropogenic flow regulation are also present. During the observation period, there were fundamentally two completely different conditions in terms of runoff formation. First, October 2019 - October 2020, there was abnormal low spring freshet instead there was high rain flood in summer. In October 2020 - October 2021 there was a normal intra-annual flow pattern with high spring freshet. The new data of stable isotope signature of river runoff component can help to study the response of a river runoff to changing climate conditions. [ABSTRACT FROM AUTHOR]

Published
2022
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31. Estimation of gas record alteration in very low-accumulation ice cores

Author

Kévin Fourteau, Vladimir Ya. Lipenkov, Xavier Faïn, Jérôme Chappellaz, Patricia Martinerie, Alexey A. Ekaykin, Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Arctic and Antarctic Research Institute (AARI), and Russian Federal Service for Hydrometeorology and Environmental Monitoring (Roshydromet)

Subjects
010506 paleontology, 010504 meteorology & atmospheric sciences, Antarctic Plateau, lcsh:Environmental protection, Stratigraphy, Mineralogy, age structure, 01 natural sciences, Methane, chemistry.chemical_compound, lcsh:Environmental pollution, Ice core, lcsh:TD169-171.8, Glacial period, lcsh:Environmental sciences, 0105 earth and related environmental sciences, estimation method, lcsh:GE1-350, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, geography, geography.geographical_feature_category, Bedrock, methane, Firn, Paleontology, carbon dioxide, Glacier, East Antarctica, chemistry, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, lcsh:TD172-193.5, Carbon dioxide, Antarctica, Layering, ice core, Geology
Abstract

We measured the methane mixing ratios of enclosed air in five ice core sections drilled on the East Antarctic Plateau. Our work aims to study two effects that alter the recorded gas concentrations in ice cores: layered gas trapping artifacts and firn smoothing. Layered gas trapping artifacts are due to the heterogeneous nature of polar firn, where some strata might close early and trap abnormally old gases that appear as spurious values during measurements. The smoothing is due to the combined effects of diffusive mixing in the firn and the progressive closure of bubbles at the bottom of the firn. Consequently, the gases trapped in a given ice layer span a distribution of ages. This means that the gas concentration in an ice layer is the average value over a certain period of time, which removes the fast variability from the record. Here, we focus on the study of East Antarctic Plateau ice cores, as these low-accumulation ice cores are particularly affected by both layering and smoothing. We use high-resolution methane data to test a simple trapping model reproducing the layered gas trapping artifacts for different accumulation conditions typical of the East Antarctic Plateau. We also use the high-resolution methane measurements to estimate the gas age distributions of the enclosed air in the five newly measured ice core sections. It appears that for accumulations below 2 cm ice equivalent yr−1 the gas records experience nearly the same degree of smoothing. We therefore propose to use a single gas age distribution to represent the firn smoothing observed in the glacial ice cores of the East Antarctic Plateau. Finally, we used the layered gas trapping model and the estimation of glacial firn smoothing to quantify their potential impacts on a hypothetical 1.5-million-year-old ice core from the East Antarctic Plateau. Our results indicate that layering artifacts are no longer individually resolved in the case of very thinned ice near the bedrock. They nonetheless contribute to slight biases of the measured signal (less than 10 ppbv and 0.5 ppmv in the case of methane using our currently established continuous CH4 analysis and carbon dioxide, respectively). However, these biases are small compared to the dampening experienced by the record due to firn smoothing.

Published
2020

32. Pingo development in Grøndalen, West Spitsbergen

Author

Mikhail A. Anisimov, Lutz Schirmeister, Sergey Verkulich, Hanno Meyer, Andy Hodson, Aleksey Ekaykin, Sebastian Wetterich, Nikita Demidov, and Vasily Demidov

Subjects
geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, δ18O, Landform, 0211 other engineering and technologies, Geochemistry, 021107 urban & regional planning, 02 engineering and technology, Groundwater recharge, Permafrost, 01 natural sciences, 13. Climate action, Aggradation, Pingo, Meltwater, Groundwater, Geology, 0105 earth and related environmental sciences
Abstract

Pingos are common features in permafrost regions that form by subsurface massive-ice aggradation and create hill-like landforms. Pingos on Spitsbergen have been previously studied to explore their structure, formation timing, connection to springs as well as their role in post-glacial landform evolution. However, detailed hydrochemical and stable-isotope studies of massive ice samples recovered by drilling has yet to be used to study the origin and freezing conditions in pingos. Our core record of 20.7 m thick massive pingo ice from Grøndalen differentiates into four units: two characterised by decreasing δ18O and δD and increasing d (units I and III), and two others show the opposite trend (units II and IV). These delineate changes between episodes of closed-system freezing with only slight recharge inversions of the water reservoir, and more complicated episodes of groundwater freezing under semi-closed conditions when the reservoir got recharged. The water source for pingo formation shows similarity to spring water data from the valley with prevalent Na+ and HCO3- ions. The sub-permafrost groundwater originates from subglacial meltwater that most probably followed the fault structures of Grøndalen and Bøhmdalen. Today the pingo of Grøndalen is relict and degrading due to warming surface temperatures. The state of pingos on Spitsbergen depends on complex interaction of climate, permafrost and groundwater hydrology conditions, and is thus highly sensitive to climate warming.

Published
2019

33. Pingo drilling reveals sodium–chloride‐dominated massive ice in Grøndalen, Spitsbergen.

Author

Demidov, Vasiliy, Wetterich, Sebastian, Demidov, Nikita, Schirrmeister, Lutz, Verkulich, Sergey, Koshurnikov, Andrey, Gagarin, Vladimir, Ekaykin, Aleksey, Terekchov, Anton, Veres, Arina, and Kozachek, Anna

Subjects
ICE, MARINE sediments, FAULT zones, SODIUM ions, SULFIDE minerals, SALT, CHLORIDE ions
Abstract

Drilling of a 21.8‐m‐deep borehole on top of the 10.5‐m‐high Nori pingo that stands at 32 m asl in Grøndalen Valley (Spitsbergen) revealed a 16.1‐m‐thick massive ice enclosed by frozen sediments. The hydrochemical compositions of both the massive ice and the sediment extract show a prevalence of Na+ and Cl− ions throughout the core. The upper part of the massive ice (stage A) has low mineralization and shows an isotopically closed‐system trend in δ18O and δD isotopes decreasing down‐core. Stage B exhibits high mineralization and an isotopically semi‐open system. The crystallographic structure of Nori pingo's massive ice provides evidence of several large groundwater intrusions that support the defined formation stages. Analysis of local aquifers leads to suggest that the pingo was hydraulically sourced through a local fault zone by low mineralized sodium–bicarbonate groundwater of a Paleogene strata aquifer. This groundwater was enriched by sodium and chloride ions while filtering through marine valley sediments with residual salinity. The comparison between the sodium–chloride‐dominated massive ice of the Nori pingo and the sodium–bicarbonate‐dominated ice of the adjacent Fili pingo that stands higher up the valley may serve as an indicator for groundwater source patterns of other Nordenskiöld Land pingos. [ABSTRACT FROM AUTHOR]

Published
2021
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34. Drilling the new 5G-5 branch hole at Vostok Station for collecting a replicate core of old meteoric ice.

Author

Turkeev, Aleksei V., Vasilev, Nikolai I., Lipenkov, Vladimir Ya., Bolshunov, Alexey V., Ekaykin, Alexey A., Dmitriev, Andrei N., and Vasilev, Dmitrii A.

Subjects
ICE cores, PALEOCLIMATOLOGY, MILLING cutters, DRILLING & boring, 5G networks
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. [ABSTRACT FROM AUTHOR]

Published
2021
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35. A global multiproxy database for temperature reconstructions of the Common Era

Author

Dmitry Divine, Dmitriy V. Ovchinnikov, Hugues Goosse, Marit-Solveig Seidenkrantz, Anne Hormes, Narayan Prasad Gaire, Joelle Gergis, Katrine Husum, David J. Nash, Konrad Gajewski, Jens Zinke, Vladimir Mikhalenko, Darrell S. Kaufman, Eugene R. Wahl, Martin Grosjean, Nancy A. N. Bertler, Pierre Francus, Anastasia Gornostaeva, Diana Vladimirova, Kaustubh Thirumalai, Lucien von Gunten, Kevin J. Anchukaitis, Michael Sigl, Ryu Uemura, Michael N. Evans, Hideaki Motoyama, Scott St. George, Marie-Alexandrine Sicre, Chris S. M. Turney, Johannes P. Werner, Robert Mulvaney, Jianghao Wang, Brian M. Chase, Mark A. J. Curran, Julien Emile-Geay, Takeshi Nakatsuka, David J. Sauchyn, Nerilie J. Abram, Bronwyn C. Dixon, Raphael Neukom, Cody C. Routson, Trevor J. Porter, Selvaraj Kandasamy, Mirko Severi, Massimo Frezzotti, Steven J. Phipps, Hans W. Linderholm, A. E. Viau, P. Graham Mortyn, Jessica E. Tierney, Eric J. Steig, Heidi A. Roop, K. Halimeda Kilbourne, Jason A. Addison, Jonathan J. Tyler, Mandy Freund, Daniel A. Dixon, Belen Martrat, Chenxi Xu, Krystyna M. Saunders, Min Te Chen, Xuemei Shao, Vasile Ersek, Philipp Munz, Hans Oerter, Masaki Sano, Zhixin Hao, Meloth Thamban, Alexey A. Ekaykin, Barbara Stenni, Kazuho Horiuchi, Ignacio A. Mundo, Zicheng Yu, Gregory T. Pederson, James W. C. White, Nalan Koc, Elisabeth Isaksson, Kathryn Allen, Rixt de Jong, Jeannine-Marie St. Jacques, Andrew Lorrey, Guillaume Leduc, Quansheng Ge, Kristine L. DeLong, Kenji Kawamura, Anais Orsi, Thomas Opel, Edward R. Cook, Kate E. Sinclair, Benjamin J. Henley, Nicholas P. McKay, Helen McGregor, Andrew D. Moy, Elizabeth R. Thomas, Jesper Björklund, Helena L. Filipsson, Udya Kuwar Thapa, Casey Saenger, Northern Arizona University [Flagstaff], Australian National University (ANU), United States Geological Survey [Reston] (USGS), University of Maryland [College Park], University of Maryland System, Spanish National Research Council [Madrid] (CSIC), School of Biological, Earth and Environmental Sciences [Sydney] (BEES), University of New South Wales [Sydney] (UNSW), Oeschger Centre for Climate Change Research (OCCR), University of Bern, Dipartimento di Scienze Geologiche [Trieste], Università degli studi di Trieste, University of Texas at Austin [Austin], Department of Earth and Space Sciences [Seattle], University of Washington [Seattle], Department of Earth Sciences [Oxford], University of Oxford [Oxford], Institut des Sciences de l'Evolution de Montpellier (UMR ISEM), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École pratique des hautes études (EPHE)-Université de Montpellier (UM)-Institut de recherche pour le développement [IRD] : UR226-Centre National de la Recherche Scientifique (CNRS), Climate Change Institute (CCI), University of Maine, University of Northumbria at Newcastle [United Kingdom], Lund University [Lund], Centre Eau Terre Environnement - INRS (INRS-ETE), Institut National de la Recherche Scientifique [Québec] (INRS), Italian National agency for new technologies, Energy and sustainable economic development [Frascati] (ENEA), Nepal Academy of Science and Technology, Université Catholique de Louvain (UCL), Quaternary Geology, The University Centre in Svalbard (UNIS), Norwegian Polar Institute, Climate and Environmental Physics [Bern] (CEP), Physikalisches Institut [Bern], Universität Bern [Bern]-Universität Bern [Bern], University of Maryland Center for Environmental Science, Horn Point Laboratory, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), Universitat Autònoma de Barcelona [Barcelona] (UAB), National Institute of Polar Research [Tokyo] (NiPR), British Antarctic Survey (BAS), Natural Environment Research Council (NERC), School of Environment and Technology, University of Brighton, Abteilung Klinische Sozialmedizin, Berufs- und Umweltdermatologie, Universität Heidelberg [Heidelberg], Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), The University of Tokyo, Laboratoire de géographie physique : Environnements Quaternaires et Actuels (LGP), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Université Panthéon-Sorbonne (UP1), Aarhus University [Aarhus], Department of Chemistry, University of Florence (UNIFI), Biogéochimie-Traceurs-Paléoclimat (BTP), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN), Paul Scherrer Institute (PSI), University of the Ryukyus [Okinawa], Australian Institute of Marine Science (AIMS), PAGES 2k, Università degli studi di Trieste = University of Trieste, University of Oxford, Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Institut de recherche pour le développement [IRD] : UR226-Centre National de la Recherche Scientifique (CNRS), Climate Change Institute [Orono] (CCI), Centre Eau Terre Environnement [Québec] (INRS - ETE), Université Catholique de Louvain = Catholic University of Louvain (UCL), Universität Bern [Bern] (UNIBE)-Universität Bern [Bern] (UNIBE), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Universitat Autònoma de Barcelona (UAB), Universität Heidelberg [Heidelberg] = Heidelberg University, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), The University of Tokyo (UTokyo), Université Paris 1 Panthéon-Sorbonne (UP1)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Firenze = University of Florence (UniFI), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École pratique des hautes études (EPHE), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Emile-Geay, J., Mckay, N. P., Kaufman, D. S., Von Gunten, L., Wang, Junrong, Anchukaitis, K. J., Abram, N. J., Addison, J. A., Curran, M. A. J., Evans, M. N., Henley, B. J., Hao, Z., Martrat, B., Mcgregor, H. V., Neukom, R., Pederson, G. T., Stenni, B., Thirumalai, K., Werner, J. P., Xu, C., Divine, D. V., Dixon, B. C., Gergis, J., Mundo, I. A., Nakatsuka, T., Phipps, S. J., Routson, C. C., Steig, E. J., Tierney, J. E., Tyler, J. J., Allen, K. J., Bertler, N. A. N., Bjorklund, J., Chase, B. M., Chen, M. -T., Cook, E., De Jong, R., Delong, K. L., Dixon, D. A., Ekaykin, A. A., Ersek, V., Filipsson, H. L., Francus, P., Freund, M. B., Frezzotti, M., Gaire, N. P., Gajewski, K., Ge, Q., Goosse, H., Gornostaeva, A., Grosjean, M., Horiuchi, K., Hormes, A., Husum, K., Isaksson, E., Kandasamy, S., Kawamura, K., Kilbourne, K. H., Koc, N., Leduc, G., Linderholm, H. W., Lorrey, A. M., Mikhalenko, V., Mortyn, P. G., Motoyama, H., Moy, A. D., Mulvaney, R., Munz, P. M., Nash, D. J., Oerter, H., Opel, T., Orsi, A. J., Ovchinnikov, D. V., Porter, T. J., Roop, H. A., Saenger, C., Sano, M., Sauchyn, D., Saunders, K. M., Seidenkrantz, M. -S., Severi, M., Shao, X., Sicre, M. -A., Sigl, M., Sinclair, K., St George, S., St Jacques, J. -M., Thamban, M., Thapa, U. K., Thomas, E. R., Turney, C., Uemura, R., Viau, A. E., Vladimirova, D. O., Wahl, E. R., White, J. W. C., Yu, Z., Zinke, J., École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre National de la Recherche Scientifique (CNRS)-Institut de recherche pour le développement [IRD] : UR226, and UCL - SST/ELI/ELIC - Earth & Climate

Subjects
Data Descriptor, 010504 meteorology & atmospheric sciences, VDP::Mathematics and natural science: 400::Mathematics: 410::Statistics: 412, VDP::Matematikk og Naturvitenskap: 400::Matematikk: 410::Statistikk: 412, F800, computer.software_genre, Palaeoclimate, 01 natural sciences, Proxy (climate), CECI [CISM], calcification, data integration objective, Climate change, trace metal analysis, 910 Geography & travel, geography.geographical_feature_category, Database, G500, data acquisition system, temperature of environmental material, Computer Science Applications, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Temperature reconstruction, Statistics, Probability and Uncertainty, Tree ring, Geology, wood, Information Systems, Statistics and Probability, glacial ice, radiance, 010506 paleontology, observation design, Library and Information Sciences, archaeal metabolite, Education, time series design, stable isotope analysis, Dendrochronology, 550 Earth sciences & geology, 0105 earth and related environmental sciences, geography, Global temperature, Glacier, 15. Life on land, Sea surface temperature, sediment, 13. Climate action, North Atlantic oscillation, Oceanic basin, computer
Abstract

Reproducible climate reconstructions of the Common Era (1 CE to present) are key to placing industrial-era warming into the context of natural climatic variability. Here we present a community-sourced database of temperature-sensitive proxy records from the PAGES2k initiative. The database gathers 692 records from 648 locations, including all continental regions and major ocean basins. The records are from trees, ice, sediment, corals, speleothems, documentary evidence, and other archives. They range in length from 50 to 2000 years, with a median of 547 years, while temporal resolution ranges from biweekly to centennial. Nearly half of the proxy time series are significantly correlated with HadCRUT4.2 surface temperature over the period 1850-2014. Global temperature composites show a remarkable degree of coherence between high- and low-resolution archives, with broadly similar patterns across archive types, terrestrial versus marine locations, and screening criteria. The database is suited to investigations of global and regional temperature variability over the Common Era, and is shared in the Linked Paleo Data (LiPD) format, including serializations in Matlab, R and Python., PAGES, a core project of Future Earth, is supported by the U.S. and Swiss National Science Foundations. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Some of this work was conducted as part of the North America 2k Working Group supported by the John Wesley Powell Center for Analysis and Synthesis, funded by the U.S. Geological Survey. B. Bauer, W. Gross, and E. Gille (NOAA National Centers for Environmental Information) are gratefully acknowledged for helping assemble the data citations and creating the NCEI versions of the PAGES 2k data records. We thank all the investigators whose commitment to data sharing enables the open science ethos embodied by this project.

Published
2017

37. First glaciological investigations at Ridge B, central East Antarctica.

Author

Ekaykin, Alexey A., Bolshunov, Alexey V., Lipenkov, Vladimir Ya., Scheinert, Mirko, Eberlein, Lutz, Brovkov, Evgeniy, Popov, Sergey V., and Turkeev, Alexey V.

Subjects
DEUTERIUM oxide, STABLE isotopes, ANTARCTIC ice, ANALYTICAL chemistry, ISOTOPIC analysis
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. [ABSTRACT FROM AUTHOR]

Published
2021
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38. Non-climatic signal in ice core records: lessons from Antarctic megadunes

Author

Alexey A. Ekaykin, Lutz Eberlein, Alexey V. Turkeev, Vladimir Ya. Lipenkov, Ludwig Schröder, Mirko Scheinert, and S. V. Popov

Subjects
lcsh:GE1-350, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, δ18O, lcsh:QE1-996.5, East antarctica, 010502 geochemistry & geophysics, Snow, 01 natural sciences, lcsh:Geology, Altitude, Ice core, Ridge, Climatology, Ground-penetrating radar, Spatial variability, Geology, lcsh:Environmental sciences, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology
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 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.

Published
2018

39. Post-depositional changes in snow isotope content: preliminary results of laboratory experiments

Author

V. Lipenkov, T. Hondoh, A. Miyamoto, and A. A. Ekaykin

Subjects
Sedimentary depositional environment, Atmospheric water, Meteorology, Ice core, Isotope, Firn, Environmental science, Sublimation (phase transition), Snow, Atmospheric sciences, Isotope exchange
Abstract

Isotopic content of the snow and firn thickness is assumed to be altered significantly due to the post-depositional (PD) mass- and isotope exchange with the atmospheric water vapor. If so, these effects should be accounted for in the ice core-based isotope-temperature paleo-reconstructions. In order to study the intensity of the PD processes we set up a series of laboratory experiments. In this paper we describe in detail the experimental technique and briefly overview preliminary results. It is shown that the PD modifications in the upper layer of snow thickness are noticeably strong even under such a low temperature as −35°C (the value typical for the Central Antarctic summer). It is demonstrated that the PD isotopic changes in snow can be approximated as a linear function of the relative mass loss due to snow sublimation. Possible applications for improving the isotope-temperature paleo-reconstructions are shortly discussed.

Published
2018

41. Data Descriptor: A global multiproxy database for temperature reconstructions of the Common Era

Author

Emile-Geay, Julien, McKay, Nicholas P., Kaufman, Darrell S., Von Gunten, Lucien, Wang, Jianghao, Anchukaitis, Kevin J., Abram, Nerilie J., Addison, Jason A., Curran, Mark A J, Evans, Michael N., Henley, Benjamin J., Hao, Zhixin, Martrat, Belen, McGregor, Helen V., Neukom, Raphael, Pederson, Gregory T., Stenni, Barbara, Thirumalai, Kaustubh, Werner, Johannes P., Xu, Chenxi, Divine, Dmitry V., Dixon, Bronwyn C., Gergis, Joelle, Mundo, Ignacio A., Nakatsuka, Takeshi, Phipps, Steven J., Routson, Cody C., Steig, Eric J., Tierney, Jessica E., Tyler, Jonathan J., Allen, Kathryn J., Bertler, Nancy A. N., Bjorklund, Jesper, Chase, Brian M., Chen, Min-Te, Cook, Ed, de Jong, Rixt, DeLong, Kristine L., Dixon, Daniel A., Ekaykin, Alexey A., Ersek, Vasile, Filipsson, Helena L., Francus, Pierre, Freund, Mandy B., Frezzotti, Massimo, Gaire, Narayan P., Gajewski, Konrad, Ge, Quansheng, Goosse, Hugues, and Seidenkrantz, Marit-Solveig

Subjects
TROPICAL CLIMATE VARIABILITY, ICE-CORE RECORDS, SEA-SURFACE TEMPERATURE, PAST 3 CENTURIES, HIGH-RESOLUTION PALEOCLIMATOLOGY, NORTH-ATLANTIC OSCILLATION, TREE-RING WIDTH, OXYGEN-ISOTOPE RECORD, SUMMER TEMPERATURE, PACIFIC WARM POOL
Abstract

Reproducible climate reconstructions of the Common Era (1 CE to present) are key to placing industrial-era warming into the context of natural climatic variability. Here we present a community-sourced database of temperature-sensitive proxy records from the PAGES2k initiative. The database gathers 692 records from 648 locations, including all continental regions and major ocean basins. The records are from trees, ice, sediment, corals, speleothems, documentary evidence, and other archives. They range in length from 50 to 2000 years, with a median of 547 years, while temporal resolution ranges from biweekly to centennial. Nearly half of the proxy time series are significantly correlated with HadCRUT4.2 surface temperature over the period 1850-2014. Global temperature composites show a remarkable degree of coherence between high-and low-resolution archives, with broadly similar patterns across archive types, terrestrial versus marine locations, and screening criteria. The database is suited to investigations of global and regional temperature variability over the Common Era, and is shared in the Linked Paleo Data (LiPD) format, including serializations in Matlab, R and Python.(TABLE)Since the pioneering work of D'Arrigo and Jacoby1-3, as well as Mann et al. 4,5, temperature reconstructions of the Common Era have become a key component of climate assessments6-9. Such reconstructions depend strongly on the composition of the underlying network of climate proxies10, and it is therefore critical for the climate community to have access to a community-vetted, quality-controlled database of temperature-sensitive records stored in a self-describing format. The Past Global Changes (PAGES) 2k consortium, a self-organized, international group of experts, recently assembled such a database, and used it to reconstruct surface temperature over continental-scale regions11 (hereafter, ` PAGES2k-2013').This data descriptor presents version 2.0.0 of the PAGES2k proxy temperature database (Data Citation 1). It augments the PAGES2k-2013 collection of terrestrial records with marine records assembled by the Ocean2k working group at centennial12 and annual13 time scales. In addition to these previously published data compilations, this version includes substantially more records, extensive new metadata, and validation. Furthermore, the selection criteria for records included in this version are applied more uniformly and transparently across regions, resulting in a more cohesive data product.This data descriptor describes the contents of the database, the criteria for inclusion, and quantifies the relation of each record with instrumental temperature. In addition, the paleotemperature time series are summarized as composites to highlight the most salient decadal-to centennial-scale behaviour of the dataset and check mutual consistency between paleoclimate archives. We provide extensive Matlab code to probe the database-processing, filtering and aggregating it in various ways to investigate temperature variability over the Common Era. The unique approach to data stewardship and code-sharing employed here is designed to enable an unprecedented scale of investigation of the temperature history of the Common Era, by the scientific community and citizen-scientists alike.

Published
2017

42. Surface studies of water isotopes in Antarctica for quantitative interpretation of deep ice core data

Author

Bénédicte Minster, Amaelle Landais, Frédéric Prié, Ghislain Picard, Valerie Masson-Delmotte, Laurent Arnaud, Alexandra Touzeau, Michel Fily, Alexey A. Ekaykin, Jean-Robert Petit, Jean Jouzel, Olivier Magand, Anais J Orsi, Sentia Goursaud, Mathieu Casado, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Arctic and Antarctic Research Institute (AARI), Russian Federal Service for Hydrometeorology and Environmental Monitoring (Roshydromet), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, 010504 meteorology & atmospheric sciences, 010502 geochemistry & geophysics, Atmospheric temperature, Snow, 01 natural sciences, Proxy (climate), Ice core, 13. Climate action, Climatology, General Earth and Planetary Sciences, Cryosphere, Polar, Mean radiant temperature, Transect, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Geology, 0105 earth and related environmental sciences
Abstract

Polar ice cores are unique climate archives. Indeed, most of them have a continuous stratigraphy and present high temporal resolution of many climate variables in a single archive. While water isotopic records ( δ D or δ 18 O) in ice cores are often taken as references for past atmospheric temperature variations, their relationship to temperature is associated with a large uncertainty. Several reasons are invoked to explain the limitation of such an approach; in particular, post-deposition effects are important in East Antarctica because of the low accumulation rates. The strong influence of post-deposition processes highlights the need for surface polar research programs in addition to deep drilling programs. We present here new results on water isotopes from several recent surface programs, mostly over East Antarctica. Together with previously published data, the new data presented in this study have several implications for the climatic reconstructions based on ice core isotopic data: (1) The spatial relationship between surface mean temperature and mean snow isotopic composition over the first meters in depth can be explained quite straightforwardly using simple isotopic models tuned to d-excess vs. δ 18 O evolution in transects on the East Antarctic sector. The observed spatial slopes are significantly higher (∼ 0.7–0.8‰·°C −1 for δ 18 O vs. temperature) than seasonal slopes inferred from precipitation data at Vostok and Dome C (0.35 to 0.46‰·°C −1 ). We explain these differences by changes in condensation versus surface temperature between summer and winter in the central East Antarctic plateau, where the inversion layer vanishes in summer. (2) Post-deposition effects linked to exchanges between the snow surface and the atmospheric water vapor lead to an evolution of δ 18 O in the surface snow, even in the absence of any precipitation event. This evolution preserves the positive correlation between the δ 18 O of snow and surface temperature, but is associated with a much slower δ 18 O-vs-temperature slope than the slope observed in the seasonal precipitation. (3) Post-deposition effects clearly limit the archiving of high-resolution (seasonal) climatic variability in the polar snow, but we suggest that sites with an accumulation rate of the order of 40 kg.m −2 .yr −1 may record a seasonal cycle at shallow depths.

Published
2017

43. Climatic variability in Princess Elizabeth Land (East Antarctica) over the last 350 years

Author

Valérie Masson-Delmotte, Diana Vladimirova, Alexey A. Ekaykin, Vladimir Ya. Lipenkov, Saint Petersburg State University (SPBU), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, lcsh:Environmental protection, Stratigraphy, 010502 geochemistry & geophysics, 01 natural sciences, lcsh:Environmental pollution, Ice core, lcsh:TD169-171.8, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Southern Hemisphere, lcsh:Environmental sciences, 0105 earth and related environmental sciences, Temperature record, lcsh:GE1-350, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, Interdecadal Pacific Oscillation, Anomaly (natural sciences), Paleontology, 13. Climate action, Climatology, lcsh:TD172-193.5, Period (geology), Indian Ocean Dipole, Antarctic oscillation, Geology
Abstract

We use isotopic composition (δD) data from six sites in Princess Elizabeth Land (PEL) in order to reconstruct air temperature variability in this sector of East Antarctica over the last 350 years. First, we use the present-day instrumental mean annual surface air temperature data to demonstrate that the studied region (between Russia's Progress, Vostok and Mirny research stations) is characterized by uniform temperature variability. We thus construct a stacked record of the temperature anomaly for the whole sector for the period of 1958–2015. A comparison of this series with the Southern Hemisphere climatic indices shows that the short-term inter-annual temperature variability is primarily governed by the Antarctic Oscillation (AAO) and Interdecadal Pacific Oscillation (IPO) modes of atmospheric variability. However, the low-frequency temperature variability (with period > 27 years) is mainly related to the anomalies of the Indian Ocean Dipole (IOD) mode. We then construct a stacked record of δD for the PEL for the period of 1654–2009 from individual normalized and filtered isotopic records obtained at six different sites (PEL2016 stacked record). We use a linear regression of this record and the stacked PEL temperature record (with an apparent slope of 9 ± 5.4 ‰ °C−1) to convert PEL2016 into a temperature scale. Analysis of PEL2016 shows a 1 ± 0.6 °C warming in this region over the last 3 centuries, with a particularly cold period from the mid-18th to the mid-19th century. A peak of cooling occurred in the 1840s – a feature previously observed in other Antarctic records. We reveal that PEL2016 correlates with a low-frequency component of IOD and suggest that the IOD mode influences the Antarctic climate by modulating the activity of cyclones that bring heat and moisture to Antarctica. We also compare PEL2016 with other Antarctic stacked isotopic records. This work is a contribution to the PAGES (Past Global Changes) and IPICS (International Partnerships in Ice Core Sciences) Antarctica 2k projects.

Published
2017

44. Large-scale drivers of Caucasus climate variability in meteorological records and Mt El'brus ice cores

Author

Susanne Preunkert, Alexey A. Ekaykin, Anna Kozachek, Vladimir Ya. Lipenkov, Vladimir Mikhalenko, Patrick Ginot, Valérie Masson-Delmotte, Michel Legrand, Stanislav Kutuzov, Arctic and Antarctic Research Institute (AARI), Russian Federal Service for Hydrometeorology and Environmental Monitoring (Roshydromet), Russian Academy of Sciences [Moscow] (RAS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, Atmospheric circulation, Stratigraphy, lcsh:Environmental protection, Borehole, 010502 geochemistry & geophysics, 01 natural sciences, Proxy (climate), Ice core, lcsh:Environmental pollution, lcsh:TD169-171.8, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, lcsh:Environmental sciences, 0105 earth and related environmental sciences, lcsh:GE1-350, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, geography, geography.geographical_feature_category, Stable isotope ratio, Bedrock, Paleontology, Snow, 13. Climate action, Climatology, lcsh:TD172-193.5, Physical geography, Seasonal cycle, Geology
Abstract

A 181.8 m ice core was recovered from a borehole drilled into bedrock on the western plateau of Mt El'brus (43°20′53.9′′ N, 42°25′36.0′′ E; 5115 m a.s.l.) in the Caucasus, Russia, in 2009 (Mikhalenko et al., 2015). Here, we report on the results of the water stable isotope composition from this ice core with additional data from the shallow cores. The distinct seasonal cycle of the isotopic composition allows dating by annual layer counting. Dating has been performed for the upper 126 m of the deep core combined with 20 m from the shallow cores. The whole record covers 100 years, from 2013 back to 1914. Due to the high accumulation rate (1380 mm w.e. year−1) and limited melting, we obtained isotopic composition and accumulation rate records with seasonal resolution. These values were compared with available meteorological data from 13 weather stations in the region and also with atmosphere circulation indices, back-trajectory calculations, and Global Network of Isotopes in Precipitation (GNIP) data in order to decipher the drivers of accumulation and ice core isotopic composition in the Caucasus region. In the warm season (May–October) the isotopic composition depends on local temperatures, but the correlation is not persistent over time, while in the cold season (November–April), atmospheric circulation is the predominant driver of the ice core's isotopic composition. The snow accumulation rate correlates well with the precipitation rate in the region all year round, which made it possible to reconstruct and expand the precipitation record at the Caucasus highlands from 1914 until 1966, when reliable meteorological observations of precipitation at high elevation began.

Published
2017

45. Analytical constraints on layered gas trapping and smoothing of atmospheric variability in ice under low-accumulation conditions

Author

Kévin Fourteau, Xavier Faïn, Patricia Martinerie, Amaëlle Landais, Alexey A. Ekaykin, Vladimir Ya. Lipenkov, Jérôme Chappellaz, Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Arctic and Antarctic Research Institute (AARI), Russian Federal Service for Hydrometeorology and Environmental Monitoring (Roshydromet), Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
lcsh:GE1-350, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, paleoenvironment, lcsh:Environmental protection, methane, plateau, numerical method, analytical method, smoothing, atmospheric modeling, East Antarctica, low temperature, carbon monoxide, climate variation, mixing ratio, lcsh:Environmental pollution, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, lcsh:TD172-193.5, Antarctica, lcsh:TD169-171.8, Dansgaard-Oeschger cycle, ice core, lcsh:Environmental sciences
Abstract

We investigate for the first time the loss and alteration of past atmospheric information from air trapping mechanisms under low-accumulation conditions through continuous CH4 (and CO) measurements. Methane concentration changes were measured over the Dansgaard-Oeschger event 17 (DO-17, ĝ1/4 ĝ€†60ĝ€†000ĝ€†yrĝ€†BP) in the Antarctic Vostok 4G-2 ice core. Measurements were performed using continuous-flow analysis combined with laser spectroscopy. The results highlight many anomalous layers at the centimeter scale that are unevenly distributed along the ice core. The anomalous methane mixing ratios differ from those in the immediate surrounding layers by up to 50ĝ€†ppbv. This phenomenon can be theoretically reproduced by a simple layered trapping model, creating very localized gas age scale inversions. We propose a method for cleaning the record of anomalous values that aims at minimizing the bias in the overall signal. Once the layered-trapping-induced anomalies are removed from the record, DO-17 appears to be smoother than its equivalent record from the high-accumulation WAIS Divide ice core. This is expected due to the slower sinking and densification speeds of firn layers at lower accumulation. However, the degree of smoothing appears surprisingly similar between modern and DO-17 conditions at Vostok. This suggests that glacial records of trace gases from low-accumulation sites in the East Antarctic plateau can provide a better time resolution of past atmospheric composition changes than previously expected. We also developed a numerical method to extract the gas age distributions in ice layers after the removal of the anomalous layers based on comparison with a weakly smoothed record. It is particularly adapted for the conditions of the East Antarctic plateau, as it helps to characterize smoothing for a large range of very low-temperature and low-accumulation conditions. © Author(s) 2017.

Published
2017

46. High-resolution 900 year volcanic and climatic record from the Vostok area, East Antarctica

Author

O. P. Osipova, L. P. Golobokova, Yu. A. Shibaev, N. A. Onischuk, T. V. Khodzher, E. Y. Osipov, Alexey A. Ekaykin, and Vladimir Ya. Lipenkov

Subjects
lcsh:GE1-350, geography, geography.geographical_feature_category, Plateau, Atmospheric circulation, Dome, Firn, lcsh:QE1-996.5, Snow, lcsh:Geology, Volcano, Ice core, Climatology, Period (geology), Geology, lcsh:Environmental sciences, Earth-Surface Processes, Water Science and Technology
Abstract

Ion chromatography measurements of 1730 snow and firn samples obtained from three short cores and one pit in the Vostok station area, East Antarctica, allowed for the production of the combined volcanic record of the last 900 years (AD 1093–2010). The resolution of the record is 2–3 samples per accumulation year. In total, 24 volcanic events have been identified, including seven well-known low-latitude eruptions (Pinatubo 1991, Agung 1963, Krakatoa 1883, Tambora 1815, Huanaputina 1600, Kuwae 1452, El Chichon 1259) found in most of the polar ice cores. In comparison with three other East Antarctic volcanic records (South Pole, Plateau Remote and Dome C), the Vostok record contains more events within the last 900 years. The differences between the records may be explained by local glaciological conditions, volcanic detection methodology, and, probably, differences in atmospheric circulation patterns. The strongest volcanic signal (both in sulfate concentration and flux) was attributed to the AD 1452 Kuwae eruption, similar to the Plateau Remote and Talos Dome records. The average snow accumulation rate calculated between volcanic stratigraphic horizons for the period AD 1260–2010 is 20.9 mm H2O. Positive (+13%) anomalies of snow accumulation were found for AD 1661–1815 and AD 1992–2010, and negative (−12%) for AD 1260–1601. We hypothesized that the changes in snow accumulation are associated with regional peculiarities in atmospheric transport.

Published
2014

47. Estimation of gas record alteration in very low-accumulation ice cores.

Author

Fourteau, Kévin, Martinerie, Patricia, Faïn, Xavier, Ekaykin, Alexey A., Chappellaz, Jérôme, and Lipenkov, Vladimir

Subjects
ICE cores, CARBON dioxide analysis, GAS distribution, DRILL cores, AGE distribution
Abstract

We measured the methane mixing ratios of enclosed air in five ice core sections drilled on the East Antarctic Plateau. Our work aims to study two effects that alter the recorded gas concentrations in ice cores: layered gas trapping artifacts and firn smoothing. Layered gas trapping artifacts are due to the heterogeneous nature of polar firn, where some strata might close early and trap abnormally old gases that appear as spurious values during measurements. The smoothing is due to the combined effects of diffusive mixing in the firn and the progressive closure of bubbles at the bottom of the firn. Consequently, the gases trapped in a given ice layer span a distribution of ages. This means that the gas concentration in an ice layer is the average value over a certain period of time, which removes the fast variability from the record. Here, we focus on the study of East Antarctic Plateau ice cores, as these low-accumulation ice cores are particularly affected by both layering and smoothing. We use high-resolution methane data to test a simple trapping model reproducing the layered gas trapping artifacts for different accumulation conditions typical of the East Antarctic Plateau. We also use the high-resolution methane measurements to estimate the gas age distributions of the enclosed air in the five newly measured ice core sections. It appears that for accumulations below 2 cmiceequivalentyr-1 the gas records experience nearly the same degree of smoothing. We therefore propose to use a single gas age distribution to represent the firn smoothing observed in the glacial ice cores of the East Antarctic Plateau. Finally, we used the layered gas trapping model and the estimation of glacial firn smoothing to quantify their potential impacts on a hypothetical 1.5-million-year-old ice core from the East Antarctic Plateau. Our results indicate that layering artifacts are no longer individually resolved in the case of very thinned ice near the bedrock. They nonetheless contribute to slight biases of the measured signal (less than 10 ppbv and 0.5 ppmv in the case of methane using our currently established continuous CH4 analysis and carbon dioxide, respectively). However, these biases are small compared to the dampening experienced by the record due to firn smoothing. [ABSTRACT FROM AUTHOR]

Published
2020
Full Text
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48. Acquisition of isotopic composition for surface snow in East Antarctica and the links to climatic parameters

Author

Amaelle Landais, Emmanuel Le Meur, Joel Savarino, Shuji Fujita, Eugeni Barkan, Ryu Uemura, Mathieu Casado, Camille Risi, Mélanie Baroni, Sarah Guilbaud, Olivier Magand, Alexey A. Ekaykin, Grégory Teste, Kotaro Fukui, Alexandra Touzeau, Ilann Bourgeois, Boaz Luz, Barbara Stenni, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Departemanto di Scienze Ambientali Informatica e Statistica (DAIS), University of Ca’ Foscari [Venice, Italy], University of the Ryukyus [Okinawa], Tateyama Caldera Sabo Museum, The Graduate University for Advanced Studies, japan (SOKENDAI), National Institute of Polar Research [Tokyo] (NiPR), Laboratoire de Physico-Chimie de l'Atmosphère (LPCA), Université du Littoral Côte d'Opale, Saint Petersburg State Technical University, Saint Petersburg State Polytechnical University (SPSPU), Arctic and Antarctic Research Institute (AARI), Russian Federal Service for Hydrometeorology and Environmental Monitoring (Roshydromet), The Institute of Earth Sciences, The Hebrew University of Jerusalem (HUJ), Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Ecologie Alpine (LECA), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Université Joseph Fourier - Grenoble 1 (UJF)-Université Grenoble Alpes (UGA), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université du Littoral Côte d'Opale (ULCO), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Laboratoire d'Ecologie Alpine (LECA ), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
010504 meteorology & atmospheric sciences, WATER-STABLE ISOTOPES, DRONNING MAUD LAND, ACCUMULATION RATE, VOSTOK STATION, 010502 geochemistry & geophysics, Atmospheric sciences, 01 natural sciences, GENERAL-CIRCULATION MODEL, GLACIAL-INTERGLACIAL CHANGES, DEUTERIUM EXCESS SIGNAL, WATER-STABLE ISOTOPES, GREENLAND ICE CORES, DRONNING MAUD LAND, ACCUMULATION RATE, VOSTOK STATION, DOME-C, TEMPORAL VARIABILITY, GREENLAND ICE CORES, Dome (geology), Ice core, TEMPORAL VARIABILITY, DEUTERIUM EXCESS SIGNAL, Glacial period, Precipitation, GENERAL-CIRCULATION MODEL, [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology, lcsh:Environmental sciences, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, lcsh:GE1-350, Moisture, lcsh:QE1-996.5, GLACIAL-INTERGLACIAL CHANGES, 15. Life on land, Snow, lcsh:Geology, 13. Climate action, Settore GEO/08 - Geochimica e Vulcanologia, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Climatology, Kinetic fractionation, Stage (hydrology), DOME-C, Geology
Abstract

International audience; 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 17 O-excess) are related to δ 18 O and how they are controlled. d-excess increases in the interior of the continent (i.e., when δ 18 O decreases), due to the distillation process, whereas 17 O-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 Vos-tok, as well as in surface snow at Dome C. We note that the slope of the δ 18 O 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 Published by Copernicus Publications on behalf of the European Geosciences Union. 838 A. Touzeau et al.: Acquisition of isotopic composition for surface snow in East Antarctica 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 δ 18 O and second-order parameters are also found in the snow from four snow pits. While the d-excess remains opposed to δ 18 O in most snow pits, the 17 O-excess is no longer positively correlated to δ 18 O and even shows anti-correlation to δ 18 O at Vostok. This may be due to a strato-spheric influence at this site and/or to post-deposition processes .

Published
2016

49. Characterization of subglacial Lake Vostok as seen from physical and isotope properties of accreted ice

Author

Vladimir Ya. Lipenkov, D. Raynaud, Ekaterina V. Polyakova, Alexey A. Ekaykin, Arctic and Antarctic Research Institute (AARI), Russian Federal Service for Hydrometeorology and Environmental Monitoring (Roshydromet), Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Observatoire des Sciences de l'Univers de Grenoble (OSUG), and Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, Lake Vostok, General Mathematics, Clathrate hydrate, Borehole, Geochemistry, General Physics and Astronomy, gas hydrate, 010502 geochemistry & geophysics, 01 natural sciences, Hydrothermal circulation, accreted ice, Subglacial lake, Surface layer, isotopes, 0105 earth and related environmental sciences, gas content, General Engineering, Oceanography, 13. Climate action, Shelf ice, [SDE]Environmental Sciences, Surface water, texture, Geology
Abstract

International audience; Deep drilling at the Vostok Station has reached the surface of subglacial Lake Vostok (LV) twice—in February 2012 and January 2015. As a result, three replicate cores from boreholes 5G-1, 5G-2 and 5G-3 became available for detailed and revalidation analyses of the 230 m thickness of the accreted ice, down to its contact with water at 3769 m below the surface. The study reveals that the concentration of gases in the lake water beneath Vostok is unexpectedly low. A clear signature of the melt water in the surface layer of the lake, which is subject to refreezing on the icy ceiling of LV, has been discerned in the three different properties of the accreted ice: the ice texture, the isotopic and the gas content of the ice. These sets of data indicate in concert that poor mixing of the melt (and hydrothermal) water with the resident lake water and pronounced spatial and/or temporal variability of local hydrological conditions are likely to be the characteristics of the southern end of the lake. The latter implies that the surface water may be not representative enough to study LV's behaviour, and that direct sampling of the lake at different depths is needed in order to move ahead with our understanding of the lake's hydrological regime.

Published
2015

50. Formation of the Ice Core Isotopic Composition

Author

Ekaykin, Alexey A. and Lipenkov, Vladimir Ya.

Subjects
paleo-climate, Lake Vostok, Vostok station, Antarctica, isotopic composition, Physics::Atomic Physics, Nuclear Experiment, ice core, Physics::Geophysics
Abstract

IV. Chemical properties and isotopes, Main processes of the ice core isotopic composition formation are overviewed. Theory of isotope-temperature relationship is discussed and confirmed by a number of experimental data. The factors related to wind-driven spatial snow redistribution and post-depositional isotopic changes that may alter or weaken this relationship, are also considered. For high-resolution isotopic time-series obtained at sites with low accumulation of snow, the signal-to-noise ratio is shown to be as low as 0.25, which means that noise accounts for about 80 % of the total variance. It is demonstrated that "classical isotopic method" (based on the present-day geographical isotope-temperature slope) underestimates the amplitude of past temperature changes in Antarctica. The most likely reason for the discrepancy is the change in the moisture source conditions. After correction for the latter, the paleo-temperature reconstructions produced by the isotopic method become consistent with those obtained from borehole temperature measurements. We show that in the case of the Vostok ice core, both approaches lead to the same temperature shift of 10℃ between LGM and the present time. The isotopic composition of the basal part of the Vostok ice core, comprising frozen subglacial Lake Vostok water, is also discussed.

Published
2009

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