scholarly journals Studies on microparticles contained in medium-depth ice cores retrieved from east Dronning Maud Land, Antarctica

1994 ◽  
Vol 20 ◽  
pp. 73-79
Author(s):  
Akira Higashi ◽  
Yoshiyuki Fujii
Keyword(s):  
Elemental Composition ◽  
Depth Profile ◽  
Volcanic Ash ◽  
Ice Core ◽  
Compositional Analysis ◽  
Ice Cores ◽  
Cold Climates ◽  
Dronning Maud Land ◽  
Antarctic Research ◽  
South Sandwich Islands

SEM observations of microparticles in ice-core samples retrieved by the Japanese Antarctic Research Expedition in east Dronning Maud Land have been carried out since 1987. Morphology and elemental composition by EDS of many microparticles taken from various depths of the 700 m Mizuho ice core were compared with each other and with those of stratospheric microparticles in NASA Cosmic Dust Catalogs and microparticles hitherto found in deep ice cores retrieved in Antarctica. Number concentrations of microparticles were measured on all samples throughout the 700 m Mizuho ice core. Remarkable fluctuations found in the depth profile of the concentration seem to coincide with cold climates indicated by δ18O of the same core. Compositional analysis of volcanic ash at a depth of 500.7 m in the Mizuho ice core, dated at approximately 6000 years BP, indicates that the ash originated from the South Sandwich Islands.

scholarly journals Studies on microparticles contained in medium-depth ice cores retrieved from east Dronning Maud Land, Antarctica

1994 ◽  
Vol 20 ◽  
pp. 73-79
Author(s):  
Akira Higashi ◽  
Yoshiyuki Fujii
Keyword(s):  
Elemental Composition ◽  
Depth Profile ◽  
Volcanic Ash ◽  
Ice Core ◽  
Compositional Analysis ◽  
Ice Cores ◽  
Cold Climates ◽  
Dronning Maud Land ◽  
Antarctic Research ◽  
South Sandwich Islands

SEM observations of microparticles in ice-core samples retrieved by the Japanese Antarctic Research Expedition in east Dronning Maud Land have been carried out since 1987. Morphology and elemental composition by EDS of many microparticles taken from various depths of the 700 m Mizuho ice core were compared with each other and with those of stratospheric microparticles in NASA Cosmic Dust Catalogs and microparticles hitherto found in deep ice cores retrieved in Antarctica. Number concentrations of microparticles were measured on all samples throughout the 700 m Mizuho ice core. Remarkable fluctuations found in the depth profile of the concentration seem to coincide with cold climates indicated by δ18O of the same core. Compositional analysis of volcanic ash at a depth of 500.7 m in the Mizuho ice core, dated at approximately 6000 years BP, indicates that the ash originated from the South Sandwich Islands.

scholarly journals Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ<sup>15</sup>N measurements

2013 ◽  
Vol 9 (3) ◽  
pp. 983-999 ◽  
Author(s):  
E. Capron ◽  
A. Landais ◽  
D. Buiron ◽  
A. Cauquoin ◽  
J. Chappellaz ◽  
...  
Keyword(s):  
Accumulation Rate ◽  
Ice Core ◽  
Ice Cores ◽  
Detailed Comparison ◽  
Last Deglaciation ◽  
Depth Study ◽  
Dronning Maud Land ◽  
The Last Deglaciation ◽  
Correct Estimation ◽  
Lock In

Abstract. Correct estimation of the firn lock-in depth is essential for correctly linking gas and ice chronologies in ice core studies. Here, two approaches to constrain the firn depth evolution in Antarctica are presented over the last deglaciation: outputs of a firn densification model, and measurements of δ15N of N2 in air trapped in ice core, assuming that δ15N is only affected by gravitational fractionation in the firn column. Since the firn densification process is largely governed by surface temperature and accumulation rate, we have investigated four ice cores drilled in coastal (Berkner Island, BI, and James Ross Island, JRI) and semi-coastal (TALDICE and EPICA Dronning Maud Land, EDML) Antarctic regions. Combined with available ice core air-δ15N measurements from the EPICA Dome C (EDC) site, the studied regions encompass a large range of surface accumulation rates and temperature conditions. Our δ15N profiles reveal a heterogeneous response of the firn structure to glacial–interglacial climatic changes. While firn densification simulations correctly predict TALDICE δ15N variations, they systematically fail to capture the large millennial-scale δ15N variations measured at BI and the δ15N glacial levels measured at JRI and EDML – a mismatch previously reported for central East Antarctic ice cores. New constraints of the EDML gas–ice depth offset during the Laschamp event (~41 ka) and the last deglaciation do not favour the hypothesis of a large convective zone within the firn as the explanation of the glacial firn model–δ15N data mismatch for this site. While we could not conduct an in-depth study of the influence of impurities in snow for firnification from the existing datasets, our detailed comparison between the δ15N profiles and firn model simulations under different temperature and accumulation rate scenarios suggests that the role of accumulation rate may have been underestimated in the current description of firnification models.

Chapter 6.2 Englacial tephras of East Antarctica

2021 ◽  
pp. M55-2018-86
Author(s):  
Biancamaria Narcisi ◽  
Jean Robert Petit
Keyword(s):  
Late Quaternary ◽  
Ice Core ◽  
Ice Cores ◽  
Explosive Volcanism ◽  
Current Data ◽  
Atmospheric Composition ◽  
Antarctic Continent ◽  
South Sandwich Islands ◽  
Eastern Periphery ◽  
Age Range

AbstractDriven by successful achievements in recovering high-resolution ice records of climate and atmospheric composition through the Late Quaternary, new ice–tephra sequences from various sites of the East Antarctic Ice Sheet (EAIS) have been studied in the last two decades spanning an age range of a few centuries to 800 kyr. The tephrostratigraphic framework for the inner EAIS, based on ash occurrence in three multi-kilometre-deep ice cores, shows that the South Sandwich Islands represent a major source for tephra, highlighting the major role in the ash dispersal played by clockwise circum-Antarctic atmospheric circulation penetrating the Antarctic continent. Tephra records from the eastern periphery of the EAIS, however, are obviously influenced by explosive activity sourced in nearby Antarctic rift provinces. These tephra inventories have provided a fundamental complement to the near-vent volcanic record, in terms of both frequency/chronology of explosive volcanism and of magma chemical evolution through time. Despite recent progress, current data are still sparse. There is a need for further tephra studies to collect data from unexplored EAIS sectors, along with extending the tephra inventory back in time. Ongoing international palaeoclimatic initiatives of ice-core drilling could represent a significant motivation for the tephra community and for Quaternary Antarctic volcanologists.

scholarly journals New constraints on the gas age-ice age difference along the EPICA ice cores, 0–50 kyr

2007 ◽  
Vol 3 (3) ◽  
pp. 527-540 ◽  
Author(s):  
L. Loulergue ◽  
F. Parrenin ◽  
T. Blunier ◽  
J.-M. Barnola ◽  
R. Spahni ◽  
...  
Keyword(s):  
Ice Core ◽  
Phase Relationship ◽  
Ice Cores ◽  
Climatic Conditions ◽  
Ice Age ◽  
Age Difference ◽  
Last Deglaciation ◽  
Last Glacial Period ◽  
Polar Ice Sheets ◽  
Dronning Maud Land

Abstract. Gas is trapped in polar ice sheets at ~50–120 m below the surface and is therefore younger than the surrounding ice. Firn densification models are used to evaluate this ice age-gas age difference (Δage) in the past. However, such models need to be validated by data, in particular for periods colder than present day on the East Antarctic plateau. Here we bring new constraints to test a firn densification model applied to the EPICA Dome C (EDC) site for the last 50 kyr, by linking the EDC ice core to the EPICA Dronning Maud Land (EDML) ice core, both in the ice phase (using volcanic horizons) and in the gas phase (using rapid methane variations). We also use the structured 10Be peak, occurring 41 kyr before present (BP) and due to the low geomagnetic field associated with the Laschamp event, to experimentally estimate the Δage during this event. Our results seem to reveal an overestimate of the Δage by the firn densification model during the last glacial period at EDC. Tests with different accumulation rates and temperature scenarios do not entirely resolve this discrepancy. Although the exact reasons for the Δage overestimate at the two EPICA sites remain unknown at this stage, we conclude that current densification model simulations have deficits under glacial climatic conditions. Whatever the cause of the Δage overestimate, our finding suggests that the phase relationship between CO2 and EDC temperature previously inferred for the start of the last deglaciation (lag of CO2 by 800±600 yr) seems to be overestimated.

scholarly journals Characterizing the glaciological conditions at Halvfarryggen ice dome, Dronning Maud Land, Antarctica

2013 ◽  
Vol 59 (213) ◽  
pp. 9-20 ◽  
Author(s):  
Reinhard Drews ◽  
Carlos Martín ◽  
Daniel Steinhage ◽  
Olaf Eisen
Keyword(s):  
Flow Model ◽  
Ice Core ◽  
Ice Cores ◽  
Radar Data ◽  
Ice Thickness ◽  
Atmospheric Conditions ◽  
Ice Flow ◽  
International Partnerships ◽  
Drill Site ◽  
Dronning Maud Land

AbstractWe present a comprehensive approach (including field data, remote sensing and an anisotropic ice-flow model) to characterize Halvfarryggen ice dome in coastal Dronning Maud Land, Antarctica. This is a potential drill site for the International Partnerships in Ice Core Sciences, which has identified the need for ice cores covering atmospheric conditions during the last few millennia. We derive the surface topography, the ice stratigraphy from radar data, and accumulation rates which vary from 400 to 1670 kg m−2 a−1 due to preferred wind directions and changing surface slope. The stratigraphy shows anticlines and synclines beneath the divides. We transfer Dansgaard–Johnsen age–depth scales from the flanks along isochrones to the divide in the upper 20–50% of the ice thickness and show that they compare well with the results of a full-Stokes, anisotropic ice-flow model which predicts (1) 11 ka BP ice at 90% of the ice thickness, (2) a temporally stable divide for at least 2700–4500 years, (3) basal temperatures below the melting point (−12°C to −5°C) and (4) a highly developed crystal orientation fabric (COF). We suggest drilling into the apices of the deep anticlines, providing a good compromise between record length and temporal resolution and also facilitating studies of the interplay of anisotropic COF and ice flow.

scholarly journals High resolution climate reconstructions of recent warming using instrumental and ice core records from coastal Antarctica

MAUSAM ◽  
2021 ◽  
Vol 62 (4) ◽  
pp. 665-672
Author(s):  
MELOTH THAMBAN ◽  
SUSHANT S.NAIK ◽  
C.M. LALURAJ ◽  
R. RAVINDRA
Keyword(s):  
Climate Change ◽  
High Resolution ◽  
Southern Oscillation ◽  
Ice Core ◽  
Ice Cores ◽  
Temporal Consistency ◽  
The Past ◽  
Proxy Records ◽  
Dronning Maud Land ◽  
Land Region

In-situ observational record of Antarctic surface temperatures is rather sparse. Proxy based ice core studies are thus critical for reconstructing the past climate change on centennial and decadal time scales. The present study review the available instrumental and proxy records from the Dronning Maud Land region of East Antarctica as well as report recent evidences of Antarctic climate change and its global linkages. The monthly mean air temperature records of the Novolazarevskaya (Novo) station, which is the longest (since 1961) and continuous meteorological record in this region, revealed a significant warming trend at a rate of 0.25 °C / decade. To understand the spatial and temporal consistency of this warming, well-dated ice cores from the coastal Dronning Maud Land region were assessed. All proxy records consistently suggest an enhanced warming up to +0.12 °C / decade. This is further supported by a recent assessment of stable oxygen and hydrogen isotope proxy records from two high resolution ice cores (IND-25/B5 and IND-22/B4) from this region. Among these records, the IND-25/B5 provided ultra-high-resolution data for the past 100 years (1905-2005) and the IND-22/B4 core represented the past ~470 years (1530-2002) of Antarctic change. These ice records provided insights on the influence of solar forcing on Antarctic climate system as well as its linkages with the tropical and mid-latitude climatic modes like the Southern Annular Mode (SAM) and El Niño Southern Oscillation (ENSO). The calculated surface air temperatures using these records showed a warming by 0.06-0.1 °C / decade, with greatly enhanced warming during the past several decades (~0.4 °C / decade). It is confirmed that the coastal areas of Dronning Maud Land are indeed warming and the trend is apparently enhancing in the recent decades.

scholarly journals Ice-Coring At Mizuho Station, Antarctica, and Core Analyses: A Contribution from the Glaciological Research Program in East Dronning Maud Land, Antarctica

1988 ◽  
Vol 10 ◽  
pp. 213-213
Author(s):  
H. Narita ◽  
S. Mae ◽  
M. Nakawo ◽  
Y. Fujii ◽  
M. Yoshida ◽  
...  
Keyword(s):  
Research Program ◽  
Ice Core ◽  
Gas Content ◽  
List Type ◽  
Air Bubbles ◽  
The Core ◽  
Core Recovery ◽  
Burn Out ◽  
Dronning Maud Land ◽  
Antarctic Research

Between May 1983 and July 1984 glaciological parties of the 24th and 25th Japanese Antarctic Research Expeditions (JARE–24 and 25) carried out ice-core drilling using a thermal drill, down to 700.5 m depth at Mizuho Station (70°41'53"S, 44°19'54"E), as a part of the Glaciological Research Program in east Dronning Maud Land, Antarctica.The thermal drill, 3.9 m long and capable of taking a core 1.5 m long and 130 mm in diameter, is an improved version of a drill used by JARE–15 in 1975. The most important improvement was the monitoring system during drilling, for which a micro-computer was fitted in the drill. By using this system, such accidents as heater burn-out, tank overflow and failure of water suction would immediately be brought to our attention. The drilling speed was about 1.6 m/h, when the optimum output was 3.6 kW. The core recovery rate was above 99%.The core quality was good down to a depth of 80 m. Between 80 and 120 m, cracks were found at intervals of 0.15–0.5 m, and horizontal cracks were found continuously at intervals of 0.01 m or less.Immediately after the core was pulled, the stratigraphy was observed and bulk density was measured. A dust band, presumably volcanic particles, was seen at only 500.2 m depth during stratigraphic observation. The following analyses were carried out at Mizuho Station within a month of recovery: (1)Density determination by the hydrostatic method.(2)Measurement of total gas content.(3)Thin-section analyses, including observation of cracking around air bubbles and the crystalline texture, and ice-fabric studies.The 700.5 m core has been brought to Japan, and the following analyses are now under way: (1)Oxygen-isotope ratio.(2)Concentration of microparticles.(3)Electric conductivity.(4)Chemistry of soluble impurities.

scholarly journals The distribution and timing of tephra deposition at Siple Dome, Antarctica: possible climatic and rheologic implications

2007 ◽  
Vol 53 (183) ◽  
pp. 585-596 ◽  
Author(s):  
Anthony J. Gow ◽  
Debra A. Meese
Keyword(s):  
Volcanic Ash ◽  
Ice Core ◽  
Greenland Ice Sheet ◽  
Ice Cores ◽  
Crystalline Material ◽  
Similar Concentration ◽  
Ice Streams ◽  
Fine Grained ◽  
Potential Source ◽  
Siple Dome

Approximately 300 volcanic ash and dust layers were observed in the Siple Dome (Antarctica) ice core. Most of this tephra, deposited between 700 and 800 m depth, consisted primarily of glass shards with varying amounts of crystalline material and groundmass fragments. The pattern of distribution of tephra fallout closely replicates that found in the Byrd ice core, indicative of contemporaneous deposition at both locations. Peak fallout occurred approximately 19 500 years ago, based on methane tie points in the Siple Dome and Greenland Ice Sheet Project 2 (GISP2) ice cores. Mount Berlin was identified as a potential source of tephra, although other volcanoes in West and East Antarctica appear to have contributed ash and dust. Ice between 697 and 730 m, in which fine-grained tephra is concentrated, has undergone enhanced thinning compared to ice with a similar concentration of tephra deposited contemporaneously between 1300 and 1540 m at Byrd. It is speculated that this thinning has occurred in response to dynamic interaction between ice at Siple Dome and the two ice streams flanking it. A dramatic change to a shear fabric appears to be directly related to the higher concentration of volcanic particles in the ice between 700 and 800 m.

scholarly journals Synchronisation of the EDML and EDC ice cores for the last 52 kyr by volcanic signature matching

2007 ◽  
Vol 3 (2) ◽  
pp. 409-433 ◽  
Author(s):  
M. Severi ◽  
S. Becagli ◽  
E. Castellano ◽  
A. Morganti ◽  
R. Traversi ◽  
...  
Keyword(s):  
Time Scale ◽  
Ice Core ◽  
Ice Cores ◽  
Time Duration ◽  
Ice Flow ◽  
Common Time ◽  
Temporal Intervals ◽  
Apparent Duration ◽  
Dronning Maud Land ◽  
The One

Abstract. A common time scale for the EPICA ice cores from Dome C (EDC) and Dronning Maud Land (EDML) was established. Since EDML core was not drilled on a dome, the development of the EDML1 time scale for the EPICA ice core drilled in Dronning Maud Land was carried on by creating a detailed stratigraphic link between this core and the one drilled at Dome C, dated by a simpler 1D ice-flow model. The synchronisation between the two ice cores was built via the identification of several common volcanic signatures. This paper describes the rigorous method, using the signature of volcanic sulfate, which was employed for the last 52 kyr of the record. By evaluating the ratio R of the apparent duration of temporal intervals between couples of isochrones, the depth comparison between the two cores was turned into an estimate of anomalies between the modelled EDC and EDML glaciological age models during the studied period. On average R ranges between 0.8 and 1.2 corresponding to an uncertainty within 20% in the estimate of the time duration in at least one of the two ice cores. Significant deviations of R up to 1.4–1.5 are observed between 18 and 28 kyr BP. At this step our approach is not able to unequivocally find out which of the models is affected by the errors, but assuming the thinning function at both sites and accumulation history at Dome C, which was drilled on a dome, as being correct, this anomaly can be ascribed to a complex spatial accumulation variability (which may be different at present day and in the past) and to upstream ice flow in the area of the EDML core.

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;

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