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| Titel |
The impact of ice layers on gas transport through firn at the North Greenland Eemian Ice Drilling (NEEM) site, Greenland |
| VerfasserIn |
K. Keegan, M. R. Albert, I. Baker |
| 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. 5 ; Nr. 8, no. 5 (2014-10-01), S.1801-1806 |
| Datensatznummer |
250116320
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| Publikation (Nr.) |
 copernicus.org/tc-8-1801-2014.pdf |
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| Zusammenfassung |
| Typically, gas transport through firn is modeled in the context of an
idealized firn column. However, in natural firn, imperfections are present,
which can alter transport dynamics and therefore reduce the accuracy of
reconstructed climate records. For example, ice layers have been found in
several firn cores collected in the polar regions. Here, we examined the
effects of two ice layers found in a NEEM, Greenland firn core on gas
transport through the firn. These ice layers were found to have permeability
values of 3.0 and 4.0 × 10−10 m2, and are therefore not
impermeable layers. However, the shallower ice layer was found to be
significantly less permeable than the surrounding firn, and can therefore
retard gas transport. Large closed bubbles were found in the deeper ice
layer, which will have an altered gas composition than that expected because they
were closed near the surface after the water phase was present. The bubbles
in this layer represent 12% of the expected closed porosity of this firn
layer after the firn-ice transition depth is reached, and will therefore
bias the future ice core gas record. The permeability and thickness of the
ice layers at the North Greenland Eemian Ice Drilling (NEEM) site suggest that they do not disrupt the firn-air
concentration profiles and that they do not need to be accounted for in gas transport
models at NEEM. |
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