scholarly journals Past Changes of the Antarctic Ice Sheet in Terre Adélie as Deduced from Ice-Core Data and Ice Modelling (Abstract)

1984 ◽  
Vol 5 ◽  
pp. 239-239
Author(s):  
N.W. Young ◽  
D. Raynaud ◽  
M. de Angelis ◽  
J.-R. Petit ◽  
C. Lorius
Keyword(s):  
Ice Core ◽  
Ice Sheet ◽  
Antarctic Ice Sheet ◽  
Core Data ◽  
Terre Adélie ◽  
The Antarctic

scholarly journals Past Changes of the Antarctic Ice Sheet in Terre Adélie as Deduced from Ice-Core Data and Ice Modelling (Abstract)

1984 ◽  
Vol 5 ◽  
pp. 239 ◽  
Author(s):  
N.W. Young ◽  
D. Raynaud ◽  
M. de Angelis ◽  
J.-R. Petit ◽  
C. Lorius
Keyword(s):  
Ice Core ◽  
Ice Sheet ◽  
Antarctic Ice Sheet ◽  
Core Data ◽  
Terre Adélie ◽  
The Antarctic

scholarly journals Simulation of the Antarctic ice sheet with a three-dimensional polythermal ice-sheet model, in support of the EPICA project

1998 ◽  
Vol 27 ◽  
pp. 201-206 ◽  
Author(s):  
R. Calov ◽  
A. Savvin ◽  
R. Greve ◽  
I. Hansen ◽  
K. Hutter
Keyword(s):  
Shear Deformation ◽  
Ice Core ◽  
Three Dimensional ◽  
Ice Sheet ◽  
Climate Forcing ◽  
Drilling Process ◽  
Antarctic Ice Sheet ◽  
Atlantic Sector ◽  
Dronning Maud Land ◽  
The Antarctic

The three-dimensional polythermal ice-sheet model SICOPOLIS is applied to the entire Antarctic ice sheet in support of the European Project for Ice Coring in Antartica (EPICA). in this study, we focus on the deep ice core to be drilled in Dronning Maud Land (Atlantic sector of East Antarctica) as part of EPICA. It has not yel been decided where the exact drill-site will be situated. Our objective is to support EPICA during its planning phase as well as during the actual drilling process. We discuss a transient simulation with a climate forcing derived from the Vostok ice core and the SPECMAP sea-level record. This simulation shows the range of accumulation, basal temperature, age and shear deformation to be expected in the region of Dronning Maud Land. Based on these results, a possible coring position is proposed, and the distribution of temperature, age, horizontal velocity and shear deformation is shown for this column.

scholarly journals Modelling the Antarctic Ice Sheet across the Mid Pleistocene Transition – Implications for Oldest Ice

2019 ◽  
Author(s):  
Johannes Sutter ◽  
Hubertus Fischer ◽  
Klaus Grosfeld ◽  
Nanna B. Karlsson ◽  
Thomas Kleiner ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Ice Core ◽  
Ice Sheet ◽  
Middle Pleistocene ◽  
Climate Modelling ◽  
Geothermal Heat ◽  
Ice Dynamics ◽  
Antarctic Ice Sheet ◽  
Pleistocene Climate ◽  
The Antarctic

Abstract. The international endeavour to retrieve a continuous ice core, which spans the middle Pleistocene climate transition ca. 1.2–0.9 Myr ago, encompasses a multitude of field and model-based pre-site surveys. We expand on the current efforts to locate a suitable drilling site for the oldest Antarctic ice core by means of 3D continental ice sheet modelling. To this end, we present an ensemble of ice sheet simulations spanning the last 2 Myr and employing transient boundary conditions derived from climate modelling and climate proxy records. We discuss the effects of changing climate conditions, sea level and geothermal heat flux boundary conditions on the mass balance and ice dynamics of the Antarctic Ice Sheet. Our modelling results show a range of configurational ice sheet changes across the middle Pleistocene transition, suggesting a potential shift of the West Antarctic Ice Sheet to a marine-based configuration. Despite the middle Pleistocene climate re-organisation and associated ice-dynamic changes we identify several regions conducive to conditions maintaining 1.5 Myr old ice, particularly around Dome Fuji, Dome C and Ridge B, in agreement to previous studies. This finding strengthens the notion that old ice exists in previously identified regions, while providing a dynamic continental ice sheet context.

scholarly journals Deep ice-core drilling at Dome Fuji and glaciological studies in east Dronning Maud Land, Antarctica

1998 ◽  
Vol 27 ◽  
pp. 333-337 ◽  
Author(s):  
Dome-F Deep Coring Group
Keyword(s):  
Ice Core ◽  
Ice Sheet ◽  
Field Observations ◽  
Antarctic Ice Sheet ◽  
Core Drilling ◽  
Dronning Maud Land ◽  
Tephra Layers ◽  
The Antarctic ◽  
Comprehensive Study

The Dome Fuji Project is a comprehensive study of present and past glaeiological/climatological features of the Antarctic ice sheet in east Dronning Maud Land. Field observations on a 100U km traverse route from the coast to Dome Fuji slum changes in various glaciological parameters with surface elevation and distance from the coast. Deep ice-core drilling at Dome Fuji was started in August 1995 and reached a depth of 2503.52 m in December 1996. in situ core analyses revealed 25 visible tephra layers and a number of distinct cloudy bands in the ice.

scholarly journals Geothermal flux beneath the Antarctic Ice Sheet derived from measured temperature profiles in deep boreholes

2020 ◽  
Author(s):  
Pavel Talalay ◽  
Yazhou Li ◽  
Laurent Augustin ◽  
Gary Clow ◽  
Jialin Hong ◽  
...  
Keyword(s):  
Heat Flux ◽  
Heat Flow ◽  
Ice Core ◽  
Ice Sheet ◽  
High Heat ◽  
Temperature Profiles ◽  
Measured Temperature ◽  
Geothermal Heat ◽  
Antarctic Ice Sheet ◽  
The Antarctic

Abstract. The temperature at the Antarctic ice sheet bed and the temperature gradient in subglacial rocks have been directly measured only a few times, although extensive thermodynamic modelling has been used to estimate geothermal heat flux under ice sheet. During the last five decades, deep ice-core drilling projects at six sites – Byrd, WAIS Divide, Dome C, Kohnen, Dome F, and Vostok – have succeeded in reaching to, or nearly to, the bed in inland locations in Antarctica. When temperature profiles in these boreholes and heat flow model are combined with estimations of vertical velocity, the heat flow at ice sheet base is translated to a geothermal heat flux of 117.8 ± 3.3 mW m−2 at Byrd, 67.3 ± 8.6 mW m−2 at Dome C, 79.0 ± 5.0 mW m−2 at Dome F, and −3.3 ± 5.6 mW m−2 at Vostok, close to predicted values. However, estimations at Kohnen and WAIS Divide gave flux of 161.5 ± 10.2 mW m−2 and 251.3 ± 24.1 mW m−2, respectively, far higher than that predicted by existing heat flow models. The question arises as to whether this high heat flow represents regional values, or if the Kohnen and WAIS Divide boreholes were drilled over local hot spots.

scholarly journals Sensitivity of the Antarctic ice sheets to the peak warming of Marine Isotope Stage 11

2020 ◽  
Author(s):  
Martim Mas e Braga ◽  
Jorge Bernales ◽  
Matthias Prange ◽  
Arjen P. Stroeven ◽  
Irina Rogozhina
Keyword(s):  
Sea Level ◽  
Regional Climate ◽  
Ice Core ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Initial Configuration ◽  
Antarctic Ice Sheet ◽  
Climate Conditions ◽  
The Antarctic ◽  
Antarctic Ice Sheets

Abstract. Studying the response of the Antarctic ice sheets to past climate conditions similar to the present day can provide important insights for understanding its current changes and help identify natural drivers of ice sheet retreat. The Marine Isotope Substage 11c (MIS11c) interglacial is one of the best candidates for an in-depth analysis given that at its later portion orbital parameters were close to our current interglacial. However, Antarctic ice core data indicate that although MIS11c CO2 levels were close to Pre Industrial, warmer-than-present temperatures (of about 2 °C) lasted for much longer than during other interglacials. Since the global mean sea level is thought to have been 6‐13 m higher than today, there should have been some contribution from Antarctica. While substantial work has been conducted regarding the response of the Greenland Ice Sheet to the MIS11c climate, which is believed to have contributed with 3.9–7.0 m to global sea level, both configurations of the Antarctic ice sheets and their contribution to sea level rise remain poorly constrained. We use a numerical ice-sheet model to shed light on the response of the Antarctic ice sheets to MIS11c climate conditions obtained from a combination of a suite of Antarctic ice cores and the LR04 global stack of deep-sea sediment records and climate model outputs, while assessing the model sensitivity to the uncertainties in sea level reconstructions, ice sheet initial configuration, and multi-centennial climate variability. We found that the regional climate signal of the MIS11c peak warming in Antarctica captured by the ice core records is necessary for the recorded sea level highstand to be reproduced, and that warming length was more important than magnitude. However, there is a threshold for a West Antarctic Ice Sheet collapse that lies within an envelope of 1.6 and 2.1 °C warmer-than-pre-industrial regional climate conditions. Sea level forcing and multi-centennial variability were found to have played virtually no role in driving ice sheet contraction, but the choice of initial configuration of the East Antarctic Ice Sheet provided a large source of uncertainty in the quantification of MIS11c Antarctic peak sea level contribution, which falls between 6.4 and 8.8 m.

scholarly journals Investigating the internal structure of the Antarctic ice sheet: the utility of isochrones for spatiotemporal ice-sheet model calibration

2021 ◽  
Vol 15 (8) ◽  
pp. 3839-3860
Author(s):  
Johannes Sutter ◽  
Hubertus Fischer ◽  
Olaf Eisen
Keyword(s):  
Climate Models ◽  
Ice Core ◽  
3D Structure ◽  
Ice Sheet ◽  
Surface Velocity ◽  
Sea Level Changes ◽  
Antarctic Ice Sheet ◽  
Lagrangian Tracers ◽  
Modelling Effort ◽  
The Antarctic

Abstract. Ice-sheet models are a powerful tool to project the evolution of the Greenland and Antarctic ice sheets and thus their future contribution to global sea-level changes. Testing the ability of ice-sheet models to reproduce the ongoing and past evolution of the ice cover in Greenland and Antarctica is a fundamental part of every modelling effort. However, benchmarking ice-sheet model results against real-world observations is a non-trivial process as observational data come with spatiotemporal gaps in coverage. Here, we present a new approach to assess the accuracy of ice-sheet models which makes use of the internal layering of the Antarctic ice sheet. We calculate isochrone elevations from simulated Antarctic geometries and velocities via passive Lagrangian tracers, highlighting that a good fit of the model to two-dimensional datasets such as surface velocity and ice thickness does not guarantee a good match against the 3D architecture of the ice sheet and thus correct evolution over time. We show that palaeoclimate forcing schemes derived from ice-core records and climate models commonly used to drive ice-sheet models work well to constrain the 3D structure of ice flow and age in the interior of the East Antarctic ice sheet and especially along ice divides but fail towards the ice-sheet margin. The comparison to isochronal horizons attempted here reveals that simple heuristics of basal drag can lead to an overestimation of the vertical interior ice-sheet flow especially over subglacial basins. Our model observation intercomparison approach opens a new avenue for the improvement and tuning of current ice-sheet models via a more rigid constraint on model parameterisations and climate forcing, which will benefit model-based estimates of future and past ice-sheet changes.

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