scholarly journals Anomalous flow below 2700 m in the EPICA Dome C ice core detected using δ<sup>18</sup>O of atmospheric oxygen measurements

2007 ◽  
Vol 3 (2) ◽  
pp. 341-353 ◽  
Author(s):  
G. B. Dreyfus ◽  
F. Parrenin ◽  
B. Lemieux-Dudon ◽  
G. Durand ◽  
V. Masson-Delmotte ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Northern Hemisphere ◽  
Marine Sediment ◽  
Atmospheric Oxygen ◽  
Ice Core ◽  
The Core ◽  
Sediment Records ◽  
Ice Core Record ◽  
Orbital Precession ◽  
Oxygen Measurements

Abstract. While there are no indications of mixing back to 800 000 years in the EPICA Dome C ice core record, comparison with marine sediment records shows significant differences in the timing and duration of events prior to stage 11 (~430 ka, thousands of years before 1950). A relationship between the isotopic composition of atmospheric oxygen (δ18O of O2, noted δ18Oatm) and daily northern hemisphere summer insolation has been observed for the youngest four climate cycles. Here we use this relationship with new δ18O of O2 measurements to show that anomalous flow in the bottom 500 m of the core distorts the duration of events by up to a factor of 2. By tuning δ18Oatm to orbital precession we derive a corrected thinning function and present a revised age scale for the interval corresponding to Marine Isotope Stages 11–20 in the EPICA Dome C ice core. Uncertainty in the phasing of δ18Oatm with respect to insolation variations in the precession band limits the accuracy of this new agescale to ±6 kyr (thousand of years). The previously reported ~30 kyr duration of interglacial stage 11 is unchanged. In contrast, the duration of stage 15.1 is reduced by a factor of 2, from 31 to 16 kyr.

scholarly journals Anomalous flow below 2700 m in the EPICA Dome C ice core detected using δ<sup>18</sup>O of atmospheric oxygen measurements

2007 ◽  
Vol 3 (1) ◽  
pp. 63-93 ◽  
Author(s):  
G. B. Dreyfus ◽  
F. Parrenin ◽  
B. Lemieux-Dudon ◽  
G. Durand ◽  
V. Masson-Delmotte ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Northern Hemisphere ◽  
Marine Sediment ◽  
Atmospheric Oxygen ◽  
Ice Core ◽  
The Core ◽  
Sediment Records ◽  
Ice Core Record ◽  
Orbital Precession ◽  
Oxygen Measurements

Abstract. While there are no indications of mixing back to 800 000 years in the EPICA Dome C ice core record, comparison with marine sediment records shows significant differences in the timing and duration of events prior to stage 11 (~430 ka, thousand of years before 1950). A relationship between the isotopic composition of atmospheric oxygen (δ18O of O2, noted δ18Oatm) and daily northern hemisphere summer insolation has been observed for the youngest four climate cycles. Here we use this relationship with new δ18O of O2 measurements to show that anomalous flow in the bottom 500 m of the core distorts the duration of events by up to a factor of 2. By tuning δ18Oatm to orbital precession we derive a corrected thinning function and present a revised age scale for the interval corresponding to Marine Isotope Stages 11–20 in the EPICA Dome C ice core. Uncertainty in the phasing of δ18Oatm with respect to insolation variations in the precession band limits the accuracy of this new agescale to ±6 kyr (thousand of years). The previously reported ~30 kyr duration of interglacial stage 11 is unchanged. In contrast, the duration of stage 15.1 is reduced by a factor of 2, from 31 to 16 kyr.

On the relationship between stable isotopes and major impurity species as inferred from a two-dimensional firn sampling approach at EDML, East Antarctica

2021 ◽  
Author(s):  
Thomas Münch ◽  
Maria Hörhold ◽  
Johannes Freitag ◽  
Melanie Behrens ◽  
Thomas Laepple
Keyword(s):  
Isotopic Composition ◽  
Interannual Variability ◽  
Ice Core ◽  
Ice Cores ◽  
Temperature Changes ◽  
Impurity Species ◽  
Intermittent Precipitation ◽  
Ice Core Record ◽  
Stable Oxygen ◽  
Atmospheric Variations

&lt;p&gt;Ice cores constitute a major palaeoclimate archive by recording, among many others, the atmospheric variations of stable oxygen and hydrogen isotopic composition of water and of soluble ionic impurities. While impurities are used as proxies for, e.g., variations in sea ice, marine biological activity and volcanism, stable isotope records are the main source of information for the reconstruction of polar temperature changes.&lt;/p&gt;&lt;p&gt;However, such reconstruction efforts are complicated by the fact that temperature is by far not the only driver of isotopic composition changes. A single isotopic ice-core record will comprise variations caused by a multitude of processes, from variable atmospheric circulation and moisture pathways to the intermittency of precipitation and finally to the mixing and re-location of surface snow by wind drift (stratigraphic noise). Under the assumption that specific trace components are originally deposited with the precipitated snow and its isotopic composition, the retrieved impurity records should display a similar spatial and seasonal to interannual variability as the isotope records, caused by local stratigraphic noise as well as the time-variable and intermittent precipitation patterns, respectively.&lt;/p&gt;&lt;p&gt;In this contribution, we investigate the possible relationship between isotope and impurity data at the East Antarctic low-accumulation site EDML. We sampled and analysed isotopic composition and major impurity species on a four metre deep and 50&amp;#160;metre long trench. This enables us (1) to study the spatial (horizontal times vertical) relationship in the data, and (2) to analyse and compare the seasonal and interannual variability after removing the strong contribution of local stratigraphic noise. By this, the study improves our understanding of the depositional mechanisms that play an important role for the formation of ice-core records, and it offers to investigate the potential of using impurities to correct isotopic variability in order to improve temperature reconstructions.&lt;/p&gt;

scholarly journals A new ice-core record from Lomonosovfonna, Svalbard: viewing the 1920–97 data in relation to present climate and environmental conditions

2001 ◽  
Vol 47 (157) ◽  
pp. 335-345 ◽  
Author(s):  
Elisabeth Isaksson ◽  
Veijo Pohjola ◽  
Tauno Jauhiainen ◽  
John Moore ◽  
Jean Francis Pinglot ◽  
...  
Keyword(s):  
Barents Sea ◽  
Major Ions ◽  
Accumulation Rate ◽  
Pure Shear ◽  
Ice Core ◽  
Climatic Conditions ◽  
Temperature Record ◽  
The Core ◽  
Ice Core Record ◽  
Ice Field

AbstractIn 1997 a 121 m ice core was retrieved from Lomonosovfonna, the highest ice field in Spitsbergen, Svalbard (1250 m a.s.l.). Radar measurements indicate an ice depth of 126.5 m, and borehole temperature measurements show that the ice is below the melting point. High-resolution sampling of major ions, oxygen isotopes and deuterium has been performed on the core, and the results from the uppermost 36 m suggest that quasi-annual signals are preserved. The 1963 radioactive layer is situated at 18.5–18.95 m, giving a mean annual accumulation of 0.36 m w.e. for the period 1963–96. The upper 36 m of the ice core was dated back to 1920 by counting layers provided by the seasonal variations of the ions in addition to using a constant accumulation rate, with thinning by pure shear according to Nye (1963). The stratigraphy does not seem to have been obliterated by meltwater percolation, in contrast to most previous core sites on Svalbard. The anthropogenic influence on the Svalbard environment is illustrated by increased levels of sulphate, nitrate and acidity. Both nitrate and sulphate levels started to increase in the late 1940s, remained high until the late 1980s and have decreased during the last 15 years. The records of δ18O, MSA (methane-sulphonic acid), and melt features along the core agree with the temperature record from Longyearbyen and the sea-ice record from the Barents Sea at a multi-year resolution, suggesting that this ice core reflects local climatic conditions.

scholarly journals A potential high-elevation ice-core site at Hielo Patagόnico Sur

2006 ◽  
Vol 43 ◽  
pp. 8-13 ◽  
Author(s):  
Margit Schwikowski ◽  
Sabina Brütsch ◽  
Gino Casassa ◽  
Andrés Rivera
Keyword(s):  
Wind Erosion ◽  
Ice Core ◽  
Ice Cores ◽  
High Elevation ◽  
The Core ◽  
Clear Sign ◽  
Southern Patagonia ◽  
Core Site ◽  
Ice Core Record ◽  
Good Potential

AbstractThe Patagonia icefields constitute a unique location in the Southern Hemisphere for obtaining non-polar paleo-records from ice cores south of 45°S. Nevertheless, no ice-core record with meaningful paleoclimate information has yet been obtained from Patagonia. This deficiency is due to extremely harsh field conditions, and to the fact that the main plateaus of both Hielo Patagónico Norte (HPN; northern Patagonia icefield) and Hielo Patagónico Sur (HPS; southern Patagonia icefield) are strongly affected by meltwater percolation. In order to explore the suitability of high-elevation glacier sites at HPS as paleoclimate archives, three shallow firn cores were retrieved covering the altitude range 1543−2300 ma.s.l. The glaciochemical records from the two lower sites confirm the presence of superimposed ice, a clear sign of meltwater formation and percolation. In the core from 2300 m, the glaciochemical signature appears to be preserved, indicating that no significant melting occurred. Although there might be problems associated with wind erosion and extreme melt events, there is good potential for well-preserved paleo-records within glaciers in the Patagonia icefields located higher than 2300 m.

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;

Testing the ideal ice-core record for past temperature reconstructions using combined isotope and impurity analyses

2020 ◽  
Author(s):  
Thomas Münch ◽  
Maria Hörhold ◽  
Johannes Freitag ◽  
Melanie Behrens ◽  
Thomas Laepple
Keyword(s):  
Isotopic Composition ◽  
Spatial Scales ◽  
Ice Core ◽  
Ice Cores ◽  
Dimensional Structure ◽  
True Temperature ◽  
Impurity Species ◽  
Temperature Reconstructions ◽  
Isotope Record ◽  
Ice Core Record

&lt;p&gt;Ice cores represent one of the most important palaeoclimate archives, which record, among many other parameters, changes in stable oxygen and hydrogen isotopic composition and soluble ionic impurities. While impurities serve, for example, as proxies for sea ice, marine biological activity and volcanism, records of isotopic composition are the major proxy for the reconstruction of natural polar temperature variability. The latter is based on the temperature-dependent distillation and fractionation of the isotopic composition of water vapour along its atmospheric pathway and empirically determined relationships thereof.&lt;/p&gt;&lt;p&gt;However, temperature is by far not the only driver of isotopic composition changes. A single isotopic ice-core record will comprise variations caused by a multitude of processes, from variable atmospheric circulation and moisture pathways to the intermittency of precipitation and finally to the mixing and re-location of surface snow by wind drift (stratigraphic noise). Taken together, these additional processes constitute a large amount of noise in the single isotope record, which masks the true temperature-related variability. Averaging a sufficient number of records to reduce overall noise is one means to allow for quantitative reconstructions, but its effectiveness depends on the spatial scales of the involved processes. Here, we discuss an alternative approach. Assuming that major impurity species exhibit a seasonal cycle and are mainly also, along with the isotopic composition, deposited by precipitation and redistributed by wind, a large portion of their interannual variability should be linked, which would offer the possibility of using the impurities to correct the variability of the isotopic records.&lt;/p&gt;&lt;p&gt;In this contribution, we present the &quot;ideal&quot; dataset for testing this idea. We sampled and analysed isotopic composition and major impurity species on a four metre deep and 50 metre long trench at Kohnen Station, East Antarctica. This enables us to study the two-dimensional structure and relationship of both proxies to learn about their deposition mechanisms, their seasonality, and to test the ability of a combined isotope&amp;#8211;impurity approach to reconstruct local temperatures by comparing so obtained temperature reconstructions with the local weather station data.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

scholarly journals Ice-core net snow accumulation and seasonal snow chemistry at a temperate-glacier site: Mount Waddington, southwest British Columbia, Canada

2012 ◽  
Vol 58 (212) ◽  
pp. 1165-1175 ◽  
Author(s):  
Peter D. Neff ◽  
Eric J. Steig ◽  
Douglas H. Clark ◽  
Joseph R. McConnell ◽  
Erin C. Pettit ◽  
...  
Keyword(s):  
British Columbia ◽  
Large Scale ◽  
Ice Core ◽  
Greenland Ice Sheet ◽  
Snow Accumulation ◽  
High Accumulation ◽  
Coast Mountains ◽  
Snow Chemistry ◽  
The Core ◽  
Ice Core Record

AbstractA 141m ice core was recovered from Combatant Col (51.385° N, 125.258° W; 3000ma.s.l.), Mount Waddington, Coast Mountains, British Columbia, Canada. Records of black carbon, dust, lead and water stable isotopes demonstrate that unambiguous seasonality is preserved throughout the core, despite summer surface snowmelt and temperate ice. High accumulation rates at the site (>4 m ice eq. a-1) limit modification of annual stratigraphy by percolation of surface meltwater. The ice-core record spans the period 1973–2010. An annually averaged time series of lead concentrations from the core correlates well with historical records of lead emission from North America, and with ice-core records of lead from the Greenland ice sheet. The depth-age scale for the ice core provides sufficient constraint on the vertical strain to allow estimation of the age of the ice at bedrock. Total ice thickness at Combatant Col is ~250 m; an ice core to bedrock would likely contain ice in excess of 200 years in age. Accumulation at Combatant Col is significantly correlated with both regional precipitation and large-scale geopotential height anomalies.

scholarly journals An ice-core record over the last two centuries from Penny Ice Cap, Baffin Island, Canada

2002 ◽  
Vol 35 ◽  
pp. 29-35 ◽  
Author(s):  
Kumiko Goto-Azuma ◽  
Roy M. Koerner ◽  
David A. Fisher
Keyword(s):  
Environmental Changes ◽  
Ice Core ◽  
Sea Salt ◽  
Ice Age ◽  
Baffin Island ◽  
Ion Chemistry ◽  
Sea Ice Extent ◽  
The Core ◽  
Ice Cap ◽  
Ice Core Record

AbstractIn order to reconstruct climatic and environmental changes in the Canadian Arctic, an 85 m deep ice core drilled in 1995 on Penny Ice Cap, Baffin Island, was analyzed for ions and δ18O. In addition to the core, snow-pit samples collected in 1994 and 1995 were also analyzed. Elution of ions caused by summer melting was observed in the pits. Due to the heavy summer melting on this ice cap, seasonal variations of ion chemistry and δ18O were not always present in the core. Comparisons of this core with a previously reported core drilled 2.5 maway show that the noise contained in single annual time series is 40–50% for ions and 25% for δ18O. the ice-core data, however, provide us with a reasonable proxy record of climatic and environmental changes during the last two centuries on better than a decadal basis. Sulfate and nitrate concentrations started to increase around 1900 and 1960, respectively, due to anthropogenic influx transported from the industrialized regions in North America. Sea-salt concentrations began to increase around the mid-19th century and were elevated throughout the 20th century. This trend of sea-salt concentrations is similar to that of melt percentage, which is a measure of summer temperature. Warming after the Little Ice Age would have reduced the sea-ice extent and led to the elevated sea-salt concentrations on Penny Ice Cap.

scholarly journals Ice core record of rising lead pollution in the North Pacific atmosphere

2008 ◽  
Vol 35 (5) ◽  
Author(s):  
E. Osterberg ◽  
P. Mayewski ◽  
K. Kreutz ◽  
D. Fisher ◽  
M. Handley ◽  
...  
Keyword(s):  
North Pacific ◽  
Ice Core ◽  
Lead Pollution ◽  
The North ◽  
Ice Core Record ◽  
The North Pacific
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