scholarly journals Density log of a 181 m long ice core from Berkner Island, Antarctica

1999 ◽  
Vol 29 ◽  
pp. 215-219 ◽  
Author(s):  
S. Gerland ◽  
H. Oerter ◽  
J. Kipfstuhl ◽  
F. Wilhelms ◽  
H. Miller ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Ice Core ◽  
Ice Cores ◽  
Local Effect ◽  
Absolute Accuracy ◽  
Conductivity Method ◽  
Ice Shelves ◽  
The Core ◽  
Similar Density ◽  
Electrical Conductivity Method

AbstractA 181 m long ice core was drilled at 79°36’51"S, 45°43’28" W, near the summit of Berkner Island, Antarctica (886 m a.s.L). Berkner Island is located between the Filchner and Ronne Ice Shelves, and the ice near the summit shows little lateral flow. The density of the ice core was measured every 3 mm along its length, using attenuation of a gamma-ray beam, which gave an absolute accuracy of 2%. As expected, there is a general density increase with depth, the maximum densities of > 900 kg m−3 being reached just above 100 m depth. Comparison with the electrical conductivity method (ECM) shows density variations with the same wavelength as the annual signals, which can be seen in the ECM log (higher acidity during summer). In the shallowest part of the core, the density of winter layers is higher than that of summer layers, a relationship which is reversed at greater depth. We assume that the densification rates for the two types of firn are different. Similar density phenomena were observed on ice cores from Greenland, showing that such phenomena are not a local effect.

scholarly journals Comparison of Holocene electrical records from Dome C and Vostok, Antarctica

1999 ◽  
Vol 29 ◽  
pp. 89-93 ◽  
Author(s):  
Eric Wolff ◽  
Isabelle Basile ◽  
Jean-Robert Petit ◽  
Jakob Schwander
Keyword(s):  
Electrical Conductivity ◽  
Accumulation Rate ◽  
Ice Core ◽  
Conductivity Method ◽  
Average Ratio ◽  
The Core ◽  
Electrical Methods ◽  
Dominant Influence ◽  
Electrical Conductivity Method

AbstractAs part of the European Project for Ice Goring in Antarctica, a new deep ice core is being drilled at Dome C. Two electrical methods have been used on the core drilled so far: a new design of electrical conductivity method (EGM) instrument, and a traditional dielectric profiler. The two profiles are very similar in both peaks and background, consistent with acidity being the dominant influence on both in this part of the record. The Dome C records have been compared to EGM records from Vostok, and a tentative match has been made between them. This suggests a long-term average ratio of accumulation rate of 1.36 between this Dome C core and Vostok, and that the Dome C core analyzed so far (to 358 m) probably includes the very end of the Glacial-Holocene transition.

scholarly journals Methanesulphonic acid movement in solid ice cores

2004 ◽  
Vol 39 ◽  
pp. 540-544 ◽  
Author(s):  
Barbara T. Smith ◽  
Tas D. Van Ommen ◽  
Mark A. J. Curran
Keyword(s):  
Diffusion Coefficient ◽  
Biological Activity ◽  
Sea Ice ◽  
Diffusion Mechanism ◽  
Ice Core ◽  
Ice Cores ◽  
East Antarctica ◽  
The Core ◽  
Central Value

AbstractMethanesulphonic acid (MSA) is an important trace-ion constituent in ice cores, with connections to biological activity and sea-ice distribution. Post-depositional movement of MSA has been documented in firn, and this study investigates movement in solid ice by measuring variations in MSA distribution across several horizontal sections from an ice core after 14.5 years storage. The core used is from below the bubble close-off depth at Dome Summit South, Law Dome, East Antarctica. MSA concentration was studied at 3 and 0.5 cm resolution across the core widths. Its distribution was uniform through the core centres, but the outer 3 cm showed gradients in concentrations down to less than half of the central value at the core edge. This effect is consistent with diffusion to the surrounding air during its 14.5 year storage. The diffusion coefficient is calculated to be 2 ×10–13 m2 s–1, and the implications for the diffusion mechanism are discussed.

Dating of ice cores from temperate glaciers - Significant mass loss in the accumulation area of the Adamello glacier indicated by the chronology of a 46 m ice core

2021 ◽  
Author(s):  
Theo Jenk ◽  
Daniela Festi ◽  
Margit Schwikowski ◽  
Valter Maggi ◽  
Klaus Oeggl
Keyword(s):  
Mass Loss ◽  
Ice Core ◽  
Ice Cores ◽  
Italian Alps ◽  
Accumulation Zone ◽  
The Core ◽  
Annual Layer ◽  
Significant Mass Loss ◽  
Carbon Concentrations ◽  
Significant Mass

<p>Dating glaciers is an arduous yet essential task in ice core studies, which becomes even more challenging for the dating of glaciers suffering from mass loss in the accumulation zone as result of climate warming. In this context, we present the dating of a 46 m deep ice core from the Central Italian Alps retrieved in 2016 from the Adamello glacier (Pian di Neve, 3100 m a.s.l.). We will show how the timescale for the core could be obtained by integrating results from the analyses of the radionuclides <sup>210</sup>Pb and <sup>137</sup>Cs with annual layer counting derived from pollen and refractory black carbon concentrations. Our results clearly indicate that the surface of the glacier is older than the drilling date of 2016 by about 20 years and that the 46 m ice core reaches back to around 1944. Despite the severe mass loss affecting this glacier even in the accumulation zone, we show that it is possible to obtain a reliable timescale for such a temperate glacier. These results are very encouraging and open new perspectives on the potential of such glaciers as informative palaeoarchives. We thus consider it important to present our dating approach to a broader audience.</p>

scholarly journals Polar ice stratigraphy from laser-light scattering: scattering from meltwater

1994 ◽  
Vol 40 (136) ◽  
pp. 504-508 ◽  
Author(s):  
Michael Ram ◽  
Matthias Illing
Keyword(s):  
Light Scattering ◽  
Sample Size ◽  
Tree Ring ◽  
Laser Light ◽  
Ice Core ◽  
Ice Cores ◽  
Laser Light Scattering ◽  
Polar Ice ◽  
The Core ◽  
Considerable Success

Abstract We describe a new laser-light-scattering instrument for measuring variations in dust concentration along polar ice cores. We have used this instrument with considerable success on the GISP2 ice core from central Greenland. Reproducibility is excellent and the required ice-sample size is relatively small. When combined with visual stratigraphy and ECM, the distinct annual spring/ summer dust peaks we observe can be used to date the core with tree-ring-like precision.

scholarly journals Polar ice stratigraphy from laser-light scattering: scattering from meltwater

1994 ◽  
Vol 40 (136) ◽  
pp. 504-508
Author(s):  
Michael Ram ◽  
Matthias Illing
Keyword(s):  
Light Scattering ◽  
Sample Size ◽  
Tree Ring ◽  
Laser Light ◽  
Ice Core ◽  
Ice Cores ◽  
Laser Light Scattering ◽  
Polar Ice ◽  
The Core ◽  
Considerable Success

AbstractWe describe a new laser-light-scattering instrument for measuring variations in dust concentration along polar ice cores. We have used this instrument with considerable success on the GISP2 ice core from central Greenland. Reproducibility is excellent and the required ice-sample size is relatively small. When combined with visual stratigraphy and ECM, the distinct annual spring/ summer dust peaks we observe can be used to date the core with tree-ring-like precision.

scholarly journals Issues with fracturing ice during an ice drilling project in Greenland (EastGRIP)

2020 ◽  
Author(s):  
Ilka Weikusat ◽  
David Wallis ◽  
Steven Franke ◽  
Nicolas Stoll ◽  
Julien Westhoff ◽  
...  
Keyword(s):  
Grain Size ◽  
Standard Procedure ◽  
Ice Core ◽  
Ice Sheet ◽  
Ice Cores ◽  
Orientation Distribution ◽  
Geothermal Heat ◽  
Ice Dynamics ◽  
The Core ◽  
Pulling Forces

<p>Drilling an ice core through an ice sheet (typically 2000 to 3000 m thick) is a technical challenge that nonetheless generates valuable and unique information on palaeo-climate and ice dynamics. As technically the drilling cannot be done in one run, the core has to be fractured approximately every 3 m to retrieve core sections from the bore hole. This fracture process is initiated by breaking the core with core-catchers which also clamp the engaged core in the drill head while the whole drill is then pulled up with the winch motor.</p><p> </p><p>This standard procedure is known to become difficult and requires extremely high pulling forces (Wilhelms et al. 2007), in the very deep part of the drill procedure, close to the bedrock of the ice sheet, especially when the ice material becomes warm (approximately -2°C) due to the geothermal heat released from the bedrock. Recently, during the EastGRIP (East Greenland Ice coring Project) drilling we observed a similar issue with breaking off cored sections only with extremely high pulling forces, but started from approximately 1800 m of depth, where the temperature is still very cold (approximately -20°C). This has not been observed at other ice drilling sites. As dependencies of fracture behaviour on crystal orientation and grain size are known (Schulson & Duval 2009) for ice, we thus examined the microstructure in the ice samples close to and at the core breaks.</p><p> </p><p>First preliminary results suggest that these so far unexperienced difficulties are due to the profoundly different c-axes orientation distribution (CPO) in the EastGRIP ice core. In contrast to other deep ice cores which have been drilled on ice domes or ice divides, EastGRIP is located in an ice stream. This location means that the deformation geometry (kinematics) is completely different, resulting in a different CPO (girdle pattern instead of single maximum pattern). Evidence regarding additional grain-size dependence will hopefully help to refine the fracturing procedure, which is possible due to a rather strong grain size layering observed in natural ice formed by snow precipitation.</p><p> </p><p>---------------------</p><p>Wilhelms, F.; Sheldon, S. G.; Hamann, I. & Kipfstuhl, S. Implications for and findings from deep ice core drillings - An example: The ultimate tensile strength of ice at high strain rates. Physics and Chemistry of Ice (The proceedings of the International Conference on the Physics and Chemistry of Ice held at Bremerhaven, Germany on 23-28 July 2006), <strong>2007</strong>, 635-639</p><p>Schulson, E. M. & Duval, P. Creep and Fracture of Ice. Cambridge University Press, <strong>2009</strong>, 401</p>

scholarly journals Electrical conductivity method (ECM) stratigraphic dating of the Byrd Station ice core, Antarctica

1994 ◽  
Vol 20 ◽  
pp. 115-120 ◽  
Author(s):  
C.U. Hammer ◽  
H.B. clausen ◽  
C.C. Langway
Keyword(s):  
Electrical Conductivity ◽  
Acid Concentration ◽  
Seasonal Changes ◽  
Ice Core ◽  
Strong Acid ◽  
Conductivity Method ◽  
Electrical Conductivity Method

A continuous ECM profile (strong acid concentration) has been measured along the 2191 m of ice core recovered at Byrd Station, Antarctica, in 1968. The ECM profile reveals continuous and systematic seasonal changes which are used for dating the ice core back to 50 000 bp. Hammer and others: ECM stratigraphic dating of Byrd Station ice core, Antarctica

scholarly journals Soluble Impurities In Ice Core D-1 Of Dunde Ice Cap, China, Over The Last 500 Years

1990 ◽  
Vol 14 ◽  
pp. 363
Author(s):  
Wu Xiaoling ◽  
Liu Jingsona ◽  
Yang Qinzhou
Keyword(s):  
Atmospheric Chemistry ◽  
Industrial Revolution ◽  
Environmental Changes ◽  
Ice Core ◽  
Ice Cores ◽  
Short Term ◽  
The Core ◽  
Ice Cap ◽  
National Foundation ◽  
Analysis Of Time Series

This paper gives the preliminary results of 26 trace element measurements of ice cores from Dunde Ice Cap, China. The chemical composition of soluble impurities along ice core D-1 covering the last 500 years B P., is reported and interpreted in terms of atmospheric contributions. The dust content in ice cores of Dunde Ice Cap is 36 times higher than in Byrd Station, Antarctica. Variations of soluble elements such as Ca, Mg, Κ and Na, in Dunde Ice cores are very sensitive to climatic and environmental changes. The 25 trace elements in ice core D-1 (K, Na, Ca, Mg, Cd, Cr, Co, Cu, Fe, Mn, Mo, Ni, Pb, Al, Sr, Ti, V, Zn, As, Ba, Β, Li, Ρ, S, Sn) were measured. Cationicions arranged in order of content are as follows: Ca > Na > Mg > Κ > Αl > Fe > Ζn > Cu > Μn > Pb > Cr > Ni > Co > Cd etc. The content of soluble impurities has typical terrestrial features. Rock-forming elements such as Ca, Mg, Κ, Na, Si, Al, and Fe make up 99% in the core samples. Particular attention is given to the possible impact of the so-called “pre-Industrial Revolution period” and man’s influence on the atmospheric chemistry. The spectral analysis of time series for the variation of each of the 26 contributions show a 92 year cycle that is present in the variation of all 26 ions with depth. Short-term variations, such as 23, 31, 48, 81 year cycles, are also discussed. The ice-core research program has been supported by the Chinese National Foundation of Natural Science under Grant DO125-4860011.

scholarly journals The NorthGRIP ice-core logging procedure: description and evaluation

2002 ◽  
Vol 35 ◽  
pp. 5-8 ◽  
Author(s):  
Christine Schøtt Hvidberg ◽  
Jørgen Peder Steffensen ◽  
Henrik B. Clausen ◽  
Hitoshi Shoji ◽  
Joseph Kipfstuhl
Keyword(s):  
Ice Core ◽  
Ice Cores ◽  
Depth Interval ◽  
Conductivity Measurements ◽  
The Core ◽  
The North ◽  
Core Logging ◽  
Independent Evaluation ◽  
The Difference ◽  
North Greenland

AbstractThe ice-core logging procedure used to log the North Greenland Icecore Project (NorthGRIP) ice cores is described. the existence of two deep ice cores, NorthGRIP 1and 2, drilled 25 mapart, allows an independent evaluation of the procedure. the logged depths of the NorthGRIP 1 and 2 cores deviate from the length of the unwound drill cable corrected for elongation of the cable when hanging in the hole, by 1.5‰ and 50.5‰ at depths of 1371 and 2931 m, respectively. Differences between logged depths of identified layers found in both cores are studied in the depth interval where they overlap. Layers are identified by electrical conductivity measurements and dielectric profiling. the difference between the logged depths of layers identified in both cores increases to 0.5 m close to the bottom of the NorthGRIP 1 core, which is <0.5 mm m–1 ice core. the comparison between the two cores shows that the NorthGRIP logging procedure is accurate and reproducible. Further, our results show that the temperature conditions and handling of the core during logging are important for obtaining a precise depth.

scholarly journals Chemical Evidence in Polar Ice Cores from Dielectric Profiling

1990 ◽  
Vol 14 ◽  
pp. 195-198 ◽  
Author(s):  
J.C. Moore ◽  
J.G. Paren ◽  
R. Mulvaney
Keyword(s):  
Dielectric Response ◽  
Ice Core ◽  
Ice Cores ◽  
Decisive Role ◽  
Electrical Behaviour ◽  
Polar Ice ◽  
Dielectric Relaxation Process ◽  
The Core ◽  
Ice Lattice ◽  
Chemical Evidence

The dielectric stratigraphy of a 130 m ice core from Dolleman Island, Antarctic Peninsula, shows large variations in the dielectric relaxation process and in conductivity. A comparison with the chemical stratigraphy of the core demonstrates the decisive role played by both acids and salts in determining the electrical behaviour of natural ice. The dielectric response is sensitive both to the type of impurity and to its distribution within the ice fabric. The evidence supports other observations of the localization of sulphuric acid at three-grain boundaries: in contrast, the salt impurity appears to be largely incorporated into the ice lattice. The overriding importance of the dielectric profiling technique is that it is the only profiling tool so far developed that is sensitive to the presence of salt in polar ice cores.

Sign in / Sign up

Export Citation Format

Share Document