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| Titel |
How old is the ice beneath Dome A, Antarctica? |
| VerfasserIn |
B. Sun, J. C. Moore, T. Zwinger, L. Zhao, D. Steinhage, X. Tang, D. Zhang, X. Cui, C. Martin |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1994-0416
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| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 8, no. 3 ; Nr. 8, no. 3 (2014-06-27), S.1121-1128 |
| Datensatznummer |
250116170
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| Publikation (Nr.) |
 copernicus.org/tc-8-1121-2014.pdf |
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| Zusammenfassung |
| Chinese scientists will start to drill a deep ice core at Kunlun station
near Dome A in the near future. Recent work has predicted that Dome A is a
location where ice older than 1 million years can be found. We model flow,
temperature and the age of the ice by applying a three-dimensional,
thermomechanically coupled full-Stokes model to a 70 × 70 km2
domain around Kunlun station, using isotropic non-linear rheology and
different prescribed anisotropic ice fabrics that vary the evolution from
isotropic to single maximum at 1/3 or 2/3 depths. The variation in fabric is
about as important as the uncertainties in geothermal heat flux in
determining the vertical advection which in consequence controls both the
basal temperature and the age profile. We find strongly variable basal ages
across the domain since the ice varies greatly in thickness, and any basal
melting effectively removes very old ice in the deepest parts of the
subglacial valleys. Comparison with dated radar isochrones in the upper one
third of the ice sheet cannot sufficiently constrain the age of the deeper
ice, with uncertainties as large as 500 000 years in the basal age. We also
assess basal age and thermal state sensitivities to geothermal heat flux and
surface conditions. Despite expectations of modest changes in surface height
over a glacial cycle at Dome A, even small variations in the evolution of
surface conditions cause large variation in basal conditions, which is
consistent with basal accretion features seen in radar surveys. |
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