scholarly journals "EDML1": a chronology for the EPICA deep ice core from Dronning Maud Land, Antarctica, over the last 150 000 years

2007 ◽  
Vol 3 (3) ◽  
pp. 475-484 ◽  
Author(s):  
U. Ruth ◽  
J.-M. Barnola ◽  
J. Beer ◽  
M. Bigler ◽  
T. Blunier ◽  
...  
Keyword(s):  
Time Scales ◽  
Internal Consistency ◽  
Time Scale ◽  
Ice Core ◽  
Ice Flow ◽  
Volcanic Events ◽  
Dronning Maud Land

Abstract. A chronology called EDML1 has been developed for the EPICA ice core from Dronning Maud Land (EDML). EDML1 is closely interlinked with EDC3, the new chronology for the EPICA ice core from Dome-C (EDC) through a stratigraphic match between EDML and EDC that consists of 322 volcanic match points over the last 128 ka. The EDC3 chronology comprises a glaciological model at EDC, which is constrained and later selectively tuned using primary dating information from EDC as well as from EDML, the latter being transferred using the tight stratigraphic link between the two cores. Finally, EDML1 was built by exporting EDC3 to EDML. For ages younger than 41 ka BP the new synchronized time scale EDML1/EDC3 is based on dated volcanic events and on a match to the Greenlandic ice core chronology GICC05 via 10Be and methane. The internal consistency between EDML1 and EDC3 is estimated to be typically ~6 years and always less than 450 years over the last 128 ka (always less than 130 years over the last 60 ka), which reflects an unprecedented synchrony of time scales. EDML1 ends at 150 ka BP (2417 m depth) because the match between EDML and EDC becomes ambiguous further down. This hints at a complex ice flow history for the deepest 350 m of the EDML ice core.

scholarly journals "EDML1": a chronology for the EPICA deep ice core from Dronning Maud Land, Antarctica, over the last 150 000 years

2007 ◽  
Vol 3 (2) ◽  
pp. 549-574 ◽  
Author(s):  
U. Ruth ◽  
J.-M. Barnola ◽  
J. Beer ◽  
M. Bigler ◽  
T. Blunier ◽  
...  
Keyword(s):  
Heat Flux ◽  
Time Scales ◽  
Internal Consistency ◽  
Time Scale ◽  
Ice Core ◽  
Spatial Variations ◽  
Geothermal Heat ◽  
Ice Flow ◽  
Volcanic Events ◽  
Dronning Maud Land

Abstract. A chronology called EDML1 has been developed for the EPICA ice core from Dronning Maud Land (EDML). EDML1 is closely interlinked with EDC3, the new chronology for the EPICA ice core from Dome-C (EDC) through a stratigraphic match between EDML and EDC that consists of 322 volcanic match points over the last 128 ka. The EDC3 chronology comprises a glaciological model at EDC, which is constrained and later selectively tuned using primary dating information from EDC as well as from EDML, the latter being transferred using the tight stratigraphic link between the two cores. Finally, EDML1 was built by exporting EDC3 to EDML. For ages younger than 41 ka BP EDML1/EDC3 is based on dated volcanic events and on a match to the Greenlandic GICC05 time scale via 10Be and methane. The internal consistency between EDML1 and EDC3 is estimated to be typically ~6 years and always less than 450 years over the last 128 ka (always less than 130 years over the last 60 ka), which reflects an unprecedented synchrony of time scales. EDML1 ends at 150 ka BP (2417 m depth) because the match between EDML and EDC becomes ambiguous further down. This hints to a complex ice flow history for the deepest 350 m of the EDML ice core, which amongst other reasons may be caused by spatial variations of the geothermal heat flux.

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.

Time Scale and Ice Accumulation During the Last 125,000 Years as Indicated by the Greenland 018 curve

1972 ◽  
Vol 109 (1) ◽  
pp. 17-24 ◽  
Author(s):  
N. A. Mörner
Keyword(s):  
North America ◽  
Time Scales ◽  
Time Scale ◽  
Ice Core ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Climatic Changes ◽  
Dynamic Changes ◽  
Ice Accumulation

SummaryThe 18 curve from the 1390 m long ice core from Camp Century, Greenland, shows climatic changes that are easily correlated with known glacial and non-glacial events of North America and north Europe and are thus indirectly dated. With a known chronology, the glacial dynamic changes of the Greenland Ice Sheet can be calculated for the last 125,000 years. It is concluded that the dynamics of the Greenland Ice Sheet have changed drastically during this period and that these changes are directly related to major changes of climate and extension of the Wisconsin and Weichselian glaciations. Logarithmic time scales earlier applied to this curve must therefore be incorrect.

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 The EDC3 chronology for the EPICA Dome C ice core

2007 ◽  
Vol 3 (3) ◽  
pp. 485-497 ◽  
Author(s):  
F. Parrenin ◽  
J.-M. Barnola ◽  
J. Beer ◽  
T. Blunier ◽  
E. Castellano ◽  
...  
Keyword(s):  
Pattern Matching ◽  
Time Scales ◽  
Excellent Agreement ◽  
Time Scale ◽  
Flow Model ◽  
Ice Core ◽  
Snow Accumulation ◽  
The Core ◽  
Time Periods ◽  
Paleoclimatic Records

Abstract. The EPICA (European Project for Ice Coring in Antarctica) Dome C drilling in East Antarctica has now been completed to a depth of 3260 m, at only a few meters above bedrock. Here we present the new EDC3 chronology, which is based on the use of 1) a snow accumulation and mechanical flow model, and 2) a set of independent age markers along the core. These are obtained by pattern matching of recorded parameters to either absolutely dated paleoclimatic records, or to insolation variations. We show that this new time scale is in excellent agreement with the Dome Fuji and Vostok ice core time scales back to 100 kyr within 1 kyr. Discrepancies larger than 3 kyr arise during MIS 5.4, 5.5 and 6, which points to anomalies in either snow accumulation or mechanical flow during these time periods. We estimate that EDC3 gives accurate event durations within 20% (2σ) back to MIS11 and accurate absolute ages with a maximum uncertainty of 6 kyr back to 800 kyr.

scholarly journals Records of climatic changes and volcanic events in an ice core from Central Dronning Maud Land (East Antarctica) during the past century

2002 ◽  
Vol 111 (1) ◽  
pp. 39-49 ◽  
Author(s):  
V. N. Nijampurkar ◽  
D. K. Rao ◽  
H. B. Clausen ◽  
M. K. Kaul ◽  
A. Chaturvedi
Keyword(s):  
Ice Core ◽  
Climatic Changes ◽  
East Antarctica ◽  
Past Century ◽  
The Past ◽  
Volcanic Events ◽  
Dronning Maud Land

scholarly journals Changes In Glacier Length Induced By Climate Changes

1990 ◽  
Vol 14 ◽  
pp. 355 ◽  
Author(s):  
C.F. Raymond ◽  
E.D. Waddington ◽  
Tómas Jøhannesson
Keyword(s):  
Climate Change ◽  
Steady State ◽  
Mass Balance ◽  
Time Scales ◽  
Time Scale ◽  
Longitudinal Stress ◽  
Ice Flow ◽  
Flow Models ◽  
Stress Gradients ◽  
Glacier Length

Time scales for adjustment in the length of a glacier to changing climate may be described in terms of a relatively short time scale, T S and a longer memory time, T m. The memory Tm represents the time scale needed for asymptotic approach of the glacier to a steady state following a climate change event. Tm is determined by simple continuity considerations concerning the total volume change that must occur to reach steady state and the balance rate that drives the change. We show that T m is relatively independent of the size of the climate change or to details of how ice flow is related to the geometry of the glacier. The time scale T S represents the time between a climate event and the occurrence of substantial changes in the glacier length. We show that, in contrast to T m, T s is highly dependent on the size of the climate change and on details of ice dynamics. This dependence is investigated by several ice-flow models including a simple one in which ice transport is determined by local thickness and slope, as in the analysis of kinematic waves, and a finite element representation that fully includes longitudinal stress gradients. The ice-flow models are subjected to mass-balance perturbations of varying size — from small, for which linearization approximations are valid, to large, for which linearization breaks down. The following behavior may be identified. Increasing the size of a mass-balance rate change causes a more rapid initial response of a glacier terminus, which tends to shorten T s. Longitudinal stress gradients damp local variations in velocity and thereby slow the propagation and diffusion of kinematic waves and retard the response of the terminus, which tends to lengthen T s. Longitudinal stress gradients transmit forces to the terminus region and influence the terminus motion without the necessity of redistributing mass from the glacier length into the terminus zone, which tends to shorten T s. These various results indicate that accurate modeling of the short term responses of glaciers to climate change requires fairly sophisticated ice-flow models, However, for purposes of tracking glacier lengths (or areas) over time scales considerably great than T s, fairly simple ice-flow models may suffice.

scholarly journals Predicted time-scales for GISP2 and GRIP boreholes at Summit, Greenland

1992 ◽  
Vol 38 (128) ◽  
pp. 162-168 ◽  
Author(s):  
Christine Schøtt ◽  
E. D. Waddington ◽  
C. F. Raymond
Keyword(s):  
Mass Balance ◽  
Time Scales ◽  
Ice Core ◽  
Ice Cores ◽  
Balance Model ◽  
Momentum Balance ◽  
Regional Survey ◽  
Ice Flow ◽  
The Past ◽  
Ice Velocity

AbstractTwo deep-drilling projects (GISP2 and GRIP) in central Greenland will provide ice cores for paleoclimate studies. Drilling decisions and preliminary interpretations require age-depth curves (time-scales). Using a finite-element momentum-balance model, we calculate the modern ice-flow pattern on the flowline through the two drill sites. Our model appears to require relatively soft ice either throughout the ice sheet or below the Wisconsinan-Holocene transition in order to match the modern geometry and mass balance. By scaling the ice velocity to an assumed mass-balance history throughout the past 200 000 years, we estimate the time-scales at both sites. At GISP2, a flank site, we place the 10 000 years BP isochrone (representing the Wisconsinan-Holocene transition) at 1535 m ice-equivalent depth. At GRIP, on the ice divide, the corresponding depth is 1377 m. Our calculations show ice older than 200 000 years at 100 m above the bed at both coring sites. The time-scale calculation can be used for drilling decisions and preliminary interpretations. It should be refined as more regional-survey and ice-core data become available.

scholarly journals Testing and Improving the IntCal20 Calibration Curve with Independent Records

Radiocarbon ◽  
2020 ◽  
Vol 62 (4) ◽  
pp. 1079-1094 ◽  
Author(s):  
Raimund Muscheler ◽  
Florian Adolphi ◽  
Timothy J Heaton ◽  
Christopher Bronk Ramsey ◽  
Anders Svensson ◽  
...  
Keyword(s):  
Time Scales ◽  
Calibration Curve ◽  
Time Scale ◽  
Ice Core ◽  
Volcanic Eruptions ◽  
Glacial Period ◽  
Last Glacial Period ◽  
Anchor Points ◽  
The Last Glacial

ABSTRACTConnecting calendar ages to radiocarbon (14C) ages, i.e. constructing a calibration curve, requires 14C samples that represent, or are closely connected to, atmospheric 14C values and that can also be independently dated. In addition to these data, there is information that can serve as independent tests of the calibration curve. For example, information from ice core radionuclide data cannot be directly incorporated into the calibration curve construction as it delivers less direct information on the 14C age–calendar age relationship but it can provide tests of the quality of the calibration curve. Furthermore, ice core ages on 14C-dated volcanic eruptions provide key information on the agreement of ice core and radiocarbon time scales. Due to their scarcity such data would have little impact if directly incorporated into the calibration curve. However, these serve as important “anchor points” in time for independently testing the calibration curve and/or ice-core time scales. Here we will show that such information largely supports the new IntCal20 calibration record. Furthermore, we discuss how floating tree-ring sequences on ice-core time scales agree with the new calibration curve. For the period around 40,000 years ago we discuss unresolved differences between ice core 10Be and 14C records that are possibly related to our limited understanding of carbon cycle influences on the atmospheric 14C concentration during the last glacial period. Finally, we review the results on the time scale comparison between the Greenland ice-core time scale (GICC05) and IntCal20 that effectively allow a direct comparison of 14C-dated records with the Greenland ice core data.

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

2007 ◽  
Vol 3 (3) ◽  
pp. 367-374 ◽  
Author(s):  
M. Severi ◽  
S. Becagli ◽  
E. Castellano ◽  
A. Morganti ◽  
R. Traversi ◽  
...  
Keyword(s):  
Time Scale ◽  
Ice Core ◽  
Ice Cores ◽  
Time Duration ◽  
Common Time ◽  
Signature Matching ◽  
Temporal Intervals ◽  
Apparent Duration ◽  
Dronning Maud Land ◽  
Accumulation History

Abstract. A common time scale for the EPICA ice cores from Dome C (EDC) and Dronning Maud Land (EDML) has been established. Since the 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 based on the creation of a detailed stratigraphic link between EDML and EDC, which was dated by a simpler 1D ice-flow model. The synchronisation between the two EPICA ice cores was done through 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. We estimated the discrepancies between the modelled EDC and EDML glaciological age scales during the studied period, by evaluating the ratio R of the apparent duration of temporal intervals between pairs of isochrones. On average R ranges between 0.8 and 1.2 corresponding to an uncertainty of up to 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 before present (BP), where present is defined as 1950. At this stage our approach does not allow us unequivocally to find out which of the models is affected by errors, but assuming that the thinning function at both sites and accumulation history at Dome C (which was drilled on a dome) are correct, this anomaly can be ascribed to a complex spatial accumulation variability (which may be different in the past compared to the present day) upstream of the EDML core.

Sign in / Sign up

Export Citation Format

Share Document