scholarly journals Using beryllium-10 to test the validity of past accumulation rate reconstruction from water isotope records in East Antarctic ice cores

2014 ◽  
Vol 10 (4) ◽  
pp. 3421-3447
Author(s):  
A. Cauquoin ◽  
A. Landais ◽  
G. M. Raisbeck ◽  
J. Jouzel ◽  
L. Bazin ◽  
...  
Keyword(s):  
High Resolution ◽  
Isotopic Composition ◽  
Accumulation Rate ◽  
Ice Core ◽  
Ice Cores ◽  
Temperature Reconstruction ◽  
Atmospheric Composition ◽  
Water Isotopes ◽  
Polar Regions ◽  
Water Distillation

Abstract. Ice cores are exceptional archives which allow us to reconstruct a wealth of climatic parameters as well as past atmospheric composition over the last 800 ka in Antarctica. Inferring the variations of past accumulation rate in polar regions is essential both for documenting past climate and for ice core chronology. On the East Antarctic plateau, the accumulation rate is so small that annual layers cannot be identified and accumulation rate is mainly deduced from the water isotopic composition assuming constant temporal relationships between temperature, water isotopic composition and accumulation rate. Such assumption leads to large uncertainties on the reconstructed past accumulation rate. Here, we use high resolution beryllium-10 (10Be) as an alternative tool for inferring past accumulation rate for the EPICA Dome C ice core, in East Antarctica. We present a high resolution 10Be record covering a full climatic cycle over the period 269 to 355 kyr BP from MIS 9 to MIS 10 (Marine Isotope Stages). After correcting 10Be for the estimated effect of the paleomagnetic field, we deduce that the classical estimation of accumulation rate variations from records of water isotopes agrees, with a possible underestimation of 16%, with the uncertainty on the temperature reconstruction from water isotopes in Antarctic ice cores. This is within their uncertainty of −10 to +30%. Finally, we show that the relationship between temperature and accumulation rate is comparable when using ice core data and results from several AGCM simulations run on glacial–interglacial conditions despite a larger spread in model outputs. These results indicate that the thermodynamic law linking moisture content in the air and temperature, as implemented in the different models, leads to realistic results even in polar regions, at the end of the water distillation trajectory.

scholarly journals Comparing past accumulation rate reconstructions in East Antarctic ice cores using <sup>10</sup>Be, water isotopes and CMIP5-PMIP3 models

2015 ◽  
Vol 11 (3) ◽  
pp. 355-367 ◽  
Author(s):  
A. Cauquoin ◽  
A. Landais ◽  
G. M. Raisbeck ◽  
J. Jouzel ◽  
L. Bazin ◽  
...  
Keyword(s):  
High Resolution ◽  
Isotopic Composition ◽  
Accumulation Rate ◽  
Ice Core ◽  
Ice Cores ◽  
Atmospheric Composition ◽  
Water Isotopes ◽  
Polar Regions ◽  
Antarctic Plateau ◽  
Good Agreement

Abstract. Ice cores are exceptional archives which allow us to reconstruct a wealth of climatic parameters as well as past atmospheric composition over the last 800 kyr in Antarctica. Inferring the variations in past accumulation rate in polar regions is essential both for documenting past climate and for ice core chronology. On the East Antarctic Plateau, the accumulation rate is so small that annual layers cannot be identified and accumulation rate is mainly deduced from the water isotopic composition assuming constant temporal relationships between temperature, water isotopic composition and accumulation rate. Such an assumption leads to large uncertainties on the reconstructed past accumulation rate. Here, we use high-resolution beryllium-10 (10Be) as an alternative tool for inferring past accumulation rate for the EPICA Dome C ice core, in East Antarctica. We present a high-resolution 10Be record covering a full climatic cycle over the period 269 to 355 ka from Marine Isotope Stage (MIS) 9 to 10, including a period warmer than pre-industrial (MIS 9.3 optimum). After correcting 10Be for the estimated effect of the palaeomagnetic field, we deduce that the 10Be reconstruction is in reasonably good agreement with EDC3 values for the full cycle except for the period warmer than present. For the latter, the accumulation is up to 13% larger (4.46 cm ie yr−1 instead of 3.95). This result is in agreement with the studies suggesting an underestimation of the deuterium-based accumulation for the optimum of the Holocene (Parrenin et al. 2007a). Using the relationship between accumulation rate and surface temperature from the saturation vapour relationship, the 10Be-based accumulation rate reconstruction suggests that the temperature increase between the MIS 9.3 optimum and present day may be 2.4 K warmer than estimated by the water isotopes reconstruction. We compare these reconstructions to the available model results from CMIP5-PMIP3 for a glacial and an interglacial state, i.e. for the Last Glacial Maximum and pre-industrial climates. While 3 out of 7 models show relatively good agreement with the reconstructions of the accumulation–temperature relationships based on 10Be and water isotopes, the other models either underestimate or overestimate it, resulting in a range of model results much larger than the range of the reconstructions. Indeed, the models can encounter some difficulties in simulating precipitation changes linked with temperature or water isotope content on the East Antarctic Plateau during glacial–interglacial transition and need to be improved in the future.

scholarly journals Experimental observation of transient <i>δ</i><sup>18</sup>O interaction between snow and advective airflow under various temperature gradient conditions

2017 ◽  
Vol 11 (4) ◽  
pp. 1733-1743 ◽  
Author(s):  
Pirmin Philipp Ebner ◽  
Hans Christian Steen-Larsen ◽  
Barbara Stenni ◽  
Martin Schneebeli ◽  
Aldo Steinfeld
Keyword(s):  
Temperature Gradient ◽  
Isotopic Composition ◽  
Ice Cores ◽  
Transport Processes ◽  
Water Isotopes ◽  
Polar Regions ◽  
Stable Water Isotopes ◽  
Climate History ◽  
Stable Isotopes Of Water ◽  
Past Climate Variability

Abstract. Stable water isotopes (δ18O) obtained from snow and ice samples of polar regions are used to reconstruct past climate variability, but heat and mass transport processes can affect the isotopic composition. Here we present an experimental study on the effect of airflow on the snow isotopic composition through a snow pack in controlled laboratory conditions. The influence of isothermal and controlled temperature gradient conditions on the δ18O content in the snow and interstitial water vapour is elucidated. The observed disequilibrium between snow and vapour isotopes led to the exchange of isotopes between snow and vapour under non-equilibrium processes, significantly changing the δ18O content of the snow. The type of metamorphism of the snow had a significant influence on this process. These findings are pertinent to the interpretation of the records of stable isotopes of water from ice cores. These laboratory measurements suggest that a highly resolved climate history is relevant for the interpretation of the snow isotopic composition in the field.

scholarly journals Experimental observation of transient δ<sup>18</sup>O interaction between snow and advective airflow under various temperature gradient conditions

2017 ◽  
Author(s):  
Pirmin P. Ebner ◽  
Hans Christian Steen-Larsen ◽  
Barbara Stenni ◽  
Martin Schneebeli ◽  
Aldo Steinfeld
Keyword(s):  
Temperature Gradient ◽  
Isotopic Composition ◽  
Ice Cores ◽  
Transport Processes ◽  
Water Isotopes ◽  
Polar Regions ◽  
Stable Water Isotopes ◽  
Equilibrium Processes ◽  
Stable Isotopes Of Water ◽  
Past Climate Variability

Abstract. Stable water isotopes (δ18O) obtained from snow and ice samples of polar regions are used to reconstruct past climate variability, but heat and mass transport processes can affect the isotopic composition. Here we present an experimental study on the effect on the snow isotopic composition by airflow through a snow pack in controlled laboratory conditions. The influence of isothermal and controlled temperature gradient conditions on the δ18O content in the snow and interstitial water vapor is elucidated. The observed disequilibrium between snow and vapor isotopes led to exchange of isotopes between snow and vapor under non-equilibrium processes, significantly changing the δ18O content of the snow. The type of metamorphism of the snow had a significant influence on this process. These findings are pertinent to the interpretation of the records of stable isotopes of water from ice cores. These laboratory measurements suggest that a highly resolved history is relevant for the interpretation of the snow isotopic composition in the field.

Sequence of events at high resolution during deglaciations over the last 800ka from the EDC ice core

2021 ◽  
Author(s):  
Antoine Grisart ◽  
amaelle landais ◽  
barbara stenni ◽  
ilaria crotti ◽  
valérie masson delmotte ◽  
...  
Keyword(s):  
High Resolution ◽  
Isotopic Composition ◽  
Elemental Composition ◽  
Water Cycle ◽  
Atmospheric Oxygen ◽  
Ice Core ◽  
Ice Cores ◽  
Climatic Conditions ◽  
Low Latitude ◽  
Sequence Of Events

&lt;p&gt;The EPICA Dome C (EDC) ice core has been drilled from 1996 to 2004. Its study revealed a unique 800 ka long continuous climatic record including 9 deglaciations. Ice cores contain numerous proxies in the ice and in the air trapped in bubbles (chronological constraints, greenhouse gases concentration, local temperature proxies, mid to low latitude climate proxies). Here, we focus on information provided by the isotopic (and elemental) composition of water and oxygen archived in both ice and gas matrix. On one hand, the water isotopic composition brings information on past temperatures and water cycle re-organizations:&amp;#160;&amp;#160; d&lt;sup&gt;18&lt;/sup&gt;O or dD records past temperature, whereas the combination of d&lt;sup&gt;18&lt;/sup&gt;O with dD or d&lt;sup&gt;17&lt;/sup&gt;O provide information on the past water cycle organization through d-excess and &lt;sup&gt;17&lt;/sup&gt;O-excess linked to climatic conditions of the evaporative regions. On the other hand, the elemental composition of oxygen expressed in the O&lt;sub&gt;2&lt;/sub&gt;/N&lt;sub&gt;2&lt;/sub&gt; ratio provides key information for orbital dating over the last 800 ka in complement with the isotopic composition of atmospheric oxygen (d&lt;sup&gt;18&lt;/sup&gt;O of O&lt;sub&gt;2&lt;/sub&gt; or d&lt;sup&gt;18&lt;/sup&gt;O&lt;sub&gt;atm&lt;/sub&gt;) which is related as well to the low latitude water cycle.&lt;/p&gt;&lt;p&gt;In this study, we present new high resolution records of water isotopes (d&lt;sup&gt;18&lt;/sup&gt;O, d-excess and &lt;sup&gt;17&lt;/sup&gt;O-excess) as well as high resolution measurements of O&lt;sub&gt;2&lt;/sub&gt;/N&lt;sub&gt;2&lt;/sub&gt; and d&lt;sup&gt;18&lt;/sup&gt;O&lt;sub&gt;atm&lt;/sub&gt; over the last 9 deglaciations on the EDC ice core. We first use the high resolution records of O&lt;sub&gt;2&lt;/sub&gt;/N&lt;sub&gt;2&lt;/sub&gt; and d&lt;sup&gt;18&lt;/sup&gt;O&lt;sub&gt;atm&lt;/sub&gt; to improve absolute dating constrain over the glacial terminations and discuss the link between orbital forcing and climate variations recorded in the EDC ice core. In a second part, we use d-excess, &lt;sup&gt;17&lt;/sup&gt;O-excess and d&lt;sup&gt;18&lt;/sup&gt;O&lt;sub&gt;atm&lt;/sub&gt; to constrain the relative chronology of high vs low latitude climatic events at sub-millennial scale over past deglaciations.&lt;/p&gt;

scholarly journals Accumulation variability derived from an ice core from coastal Dronning Maud Land, Antarctica

2004 ◽  
Vol 39 ◽  
pp. 339-345 ◽  
Author(s):  
Marzena Kaczmarska ◽  
Elisabeth Isaksson ◽  
Lars Karlöf ◽  
Jan-Gunnar Winther ◽  
Jack Kohler ◽  
...  
Keyword(s):  
High Resolution ◽  
Accumulation Rate ◽  
Ice Core ◽  
Austral Summer ◽  
Conductivity Measurement ◽  
Ice Cores ◽  
Electrical Conductivity Measurement ◽  
Regional Pattern ◽  
Dronning Maud Land

AbstractA 100 m long ice core was retrieved from the coastal area of Dronning Maud Land (DML), Antarctica, in the 2000/01 austral summer. The core was dated to AD 1737 by identification of volcanic horizons in dielectrical profiling and electrical conductivity measurement records in combination with seasonal layer counting from high-resolution oxygen isotope (δ18O) data. A mean long-term accumulation rate of 0.29 ma–1w.e. was derived from the high-resolution δ18O record as well as accumulation rates during periods in between the identified volcanic horizons. A statistically significant decrease in accumulation was found from about 1920 to the present. A comparison with other coastal ice cores from DML suggests that this is a regional pattern.

scholarly journals Non-climatic signal in ice core records: lessons from Antarctic megadunes

2016 ◽  
Vol 10 (3) ◽  
pp. 1217-1227 ◽  
Author(s):  
Alexey Ekaykin ◽  
Lutz Eberlein ◽  
Vladimir Lipenkov ◽  
Sergey Popov ◽  
Mirko Scheinert ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Isotopic Composition ◽  
Vertical Profile ◽  
Accumulation Rate ◽  
Climatic Variability ◽  
Ice Core ◽  
Ice Cores ◽  
Snow Accumulation ◽  
Vostok Station ◽  
Isotope Content

Abstract. We present the results of glaciological investigations in the megadune area located 30 km to the east of Vostok Station (central East Antarctica) implemented during the 58th, 59th and 60th Russian Antarctic Expedition (January 2013–2015). Snow accumulation rate and isotope content (δD, δ18O and δ17O) were measured along the 2 km profile across the megadune ridge accompanied by precise GPS altitude measurements and ground penetrating radar (GPR) survey. It is shown that the spatial variability of snow accumulation and isotope content covaries with the surface slope. The accumulation rate regularly changes by 1 order of magnitude within the distance < 1 km, with the reduced accumulation at the leeward slope of the dune and increased accumulation in the hollow between the dunes. At the same time, the accumulation rate averaged over the length of a dune wave (22 mm w.e.) corresponds well with the value obtained at Vostok Station, which suggests no additional wind-driven snow sublimation in the megadunes compared to the surrounding plateau. The snow isotopic composition is in negative correlation with the snow accumulation. Analysing dxs ∕ δD and 17O-excess ∕ δD slopes (where dxs  =  δD − 8 ⋅ δ18O and 17O-excess  =  ln(δ17O  ∕  1000 +  1) −0.528 ⋅ ln (δ18O ∕ 1000 + 1)), we conclude that the spatial variability of the snow isotopic composition in the megadune area could be explained by post-depositional snow modifications. Using the GPR data, we estimated the apparent dune drift velocity (4.6 ± 1.1 m yr−1). The full cycle of the dune drift is thus about 410 years. Since the spatial anomalies of snow accumulation and isotopic composition are supposed to drift with the dune, a core drilled in the megadune area would exhibit the non-climatic 410-year cycle of these two parameters. We simulated a vertical profile of snow isotopic composition with such a non-climatic variability, using the data on the dune size and velocity. This artificial profile is then compared with the real vertical profile of snow isotopic composition obtained from a core drilled in the megadune area. We note that the two profiles are very similar. The obtained results are discussed in terms of interpretation of data obtained from ice cores drilled beyond the megadune areas.

scholarly journals Novel automated inversion algorithm for temperature reconstruction using gas isotopes from ice cores

2018 ◽  
Vol 14 (6) ◽  
pp. 763-788
Author(s):  
Michael Döring ◽  
Markus C. Leuenberger
Keyword(s):  
Inverse Problem ◽  
Ice Core ◽  
Ice Cores ◽  
Temperature Reconstruction ◽  
Heat Diffusion ◽  
Water Isotopes ◽  
Temperature History ◽  
Reconstruction Methods ◽  
Temperature Reconstructions ◽  
Target Data

Abstract. Greenland past temperature history can be reconstructed by forcing the output of a firn-densification and heat-diffusion model to fit multiple gas-isotope data (δ15N or δ40Ar or δ15Nexcess) extracted from ancient air in Greenland ice cores using published accumulation-rate (Acc) datasets. We present here a novel methodology to solve this inverse problem, by designing a fully automated algorithm. To demonstrate the performance of this novel approach, we begin by intentionally constructing synthetic temperature histories and associated δ15N datasets, mimicking real Holocene data that we use as “true values” (targets) to be compared to the output of the algorithm. This allows us to quantify uncertainties originating from the algorithm itself. The presented approach is completely automated and therefore minimizes the “subjective” impact of manual parameter tuning, leading to reproducible temperature estimates. In contrast to many other ice-core-based temperature reconstruction methods, the presented approach is completely independent from ice-core stable-water isotopes, providing the opportunity to validate water-isotope-based reconstructions or reconstructions where water isotopes are used together with δ15N or δ40Ar. We solve the inverse problem T(δ15N, Acc) by using a combination of a Monte Carlo based iterative approach and the analysis of remaining mismatches between modelled and target data, based on cubic-spline filtering of random numbers and the laboratory-determined temperature sensitivity for nitrogen isotopes. Additionally, the presented reconstruction approach was tested by fitting measured δ40Ar and δ15Nexcess data, which led as well to a robust agreement between modelled and measured data. The obtained final mismatches follow a symmetric standard-distribution function. For the study on synthetic data, 95 % of the mismatches compared to the synthetic target data are in an envelope between 3.0 to 6.3 permeg for δ15N and 0.23 to 0.51 K for temperature (2σ, respectively). In addition to Holocene temperature reconstructions, the fitting approach can also be used for glacial temperature reconstructions. This is shown by fitting of the North Greenland Ice Core Project (NGRIP) δ15N data for two Dansgaard–Oeschger events using the presented approach, leading to results comparable to other studies.

scholarly journals Large-scale drivers of Caucasus climate variability in meteorological records and Mt Elbrus ice cores

2016 ◽  
Author(s):  
Anna Kozachek ◽  
Vladimir Mikhalenko ◽  
Valérie Masson-Delmotte ◽  
Alexey Ekaykin ◽  
Patrick Ginot ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Large Scale ◽  
Isotope Composition ◽  
Accumulation Rate ◽  
Meteorological Data ◽  
Ice Core ◽  
Ice Cores ◽  
Snow Accumulation ◽  
The Caucasus ◽  
Precipitation Record

Abstract. A 181.2 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 (Mikhalenko et al., 2015). Here, we report on the results of the water stable isotope composition from this ice core in comparison with results from shallow ice cores. There is a distinct seasonal cycle of the isotopic composition which allowed dating by annual layer counting. Dating has been performed for the upper 126 m of the deep core combined with shallow cores data. The whole record covers one century from 2013 back to 1914. Due to the high accumulation rate (1380 mm w.e. per year) and limited melting we obtained the 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-trajectories calculations and GNIP data in order to decipher the drivers of accumulation and ice core isotopic composition in the Caucasus region. In the summer season the isotopic composition depends on the local temperature, while in winter, the atmospheric circulation is the predominant driver of the ice core isotopic composition. The snow accumulation rate correlates well with the precipitation rate in the region all year round, this made it possible to reconstruct and expand the precipitation record at the Caucasus highlands from 1914 till 1966 when the reliable meteorological observations of precipitation at high elevation began.

scholarly journals A new method of resolving annual precipitation for the past millennia from Tibetan ice cores

2021 ◽  
Author(s):  
Wangbin Zhang ◽  
Shugui Hou ◽  
Shuang-Ye Wu ◽  
Hongxi Pang ◽  
Sharon B. Sneed ◽  
...  
Keyword(s):  
High Resolution ◽  
Inductively Coupled Plasma ◽  
Flow Model ◽  
Accumulation Rate ◽  
Ice Core ◽  
Ice Cores ◽  
New Method ◽  
Inductively Coupled ◽  
Ice Cap ◽  
Thinning Parameter

Abstract. Net accumulation records derived from ice cores provide the most direct measurement of past precipitation. However, quantitative reconstruction of accumulation for past millennia remains challenging due to the difficulty in identifying annual layers in the deeper sections of ice cores. In this study, we propose a new method to quantify annual accumulation from ice cores for past millennia, using as an example an ice core drilled at the Chongce ice cap in the northwestern Tibetan Plateau (TP). First, we used the Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) technology to develop an ultra-high-resolution trace element records in three sections of the ice core and identified annual layers in each section based on seasonality of these elements. Second, based on nine 14C ages determined for this ice core, we developed a two-parameter flow model to established the thinning parameter of this ice core. Finally, we converted the thickness of annual layers in the three sample sections to past accumulation rates based on the thinning parameter derived from the ice-flow model. Our results show that the mean annual accumulation rate for the three sample sections are 102 mm/year (2511–2541 a B.P.), 76 mm/year (1682–1697 a B.P.) and 84 mm/year (781–789 a B.P.). For comparison, the Holocene mean precipitation is 103 mm/year. This method has the potential to reconstruct continuous high-resolution precipitation records covering millennia or even longer time periods.

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

2017 ◽  
Vol 13 (5) ◽  
pp. 473-489 ◽  
Author(s):  
Anna Kozachek ◽  
Vladimir Mikhalenko ◽  
Valérie Masson-Delmotte ◽  
Alexey Ekaykin ◽  
Patrick Ginot ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Isotope Composition ◽  
Accumulation Rate ◽  
Ice Core ◽  
Ice Cores ◽  
Snow Accumulation ◽  
Global Network ◽  
Back Trajectory ◽  
The Caucasus ◽  
Precipitation Record

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.

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