The impact of ice layers on gas transport through firn at the North Greenland Eemian Ice Drilling (NEEM) site, Greenland
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...
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ftcopernicus:oai:publications.copernicus.org:tc23804 2023-05-15T16:26:39+02:00 The impact of ice layers on gas transport through firn at the North Greenland Eemian Ice Drilling (NEEM) site, Greenland Keegan, K. Albert, M. R. Baker, I. 2018-09-27 application/pdf https://doi.org/10.5194/tc-8-1801-2014 https://tc.copernicus.org/articles/8/1801/2014/ eng eng doi:10.5194/tc-8-1801-2014 https://tc.copernicus.org/articles/8/1801/2014/ eISSN: 1994-0424 Text 2018 ftcopernicus https://doi.org/10.5194/tc-8-1801-2014 2020-07-20T16:24:55Z 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 m 2 , 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. Text Greenland ice core North Greenland Copernicus Publications: E-Journals Greenland The Cryosphere 8 5 1801 1806 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
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English |
description |
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 m 2 , 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. |
format |
Text |
author |
Keegan, K. Albert, M. R. Baker, I. |
spellingShingle |
Keegan, K. Albert, M. R. Baker, I. The impact of ice layers on gas transport through firn at the North Greenland Eemian Ice Drilling (NEEM) site, Greenland |
author_facet |
Keegan, K. Albert, M. R. Baker, I. |
author_sort |
Keegan, K. |
title |
The impact of ice layers on gas transport through firn at the North Greenland Eemian Ice Drilling (NEEM) site, Greenland |
title_short |
The impact of ice layers on gas transport through firn at the North Greenland Eemian Ice Drilling (NEEM) site, Greenland |
title_full |
The impact of ice layers on gas transport through firn at the North Greenland Eemian Ice Drilling (NEEM) site, Greenland |
title_fullStr |
The impact of ice layers on gas transport through firn at the North Greenland Eemian Ice Drilling (NEEM) site, Greenland |
title_full_unstemmed |
The impact of ice layers on gas transport through firn at the North Greenland Eemian Ice Drilling (NEEM) site, Greenland |
title_sort |
impact of ice layers on gas transport through firn at the north greenland eemian ice drilling (neem) site, greenland |
publishDate |
2018 |
url |
https://doi.org/10.5194/tc-8-1801-2014 https://tc.copernicus.org/articles/8/1801/2014/ |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland ice core North Greenland |
genre_facet |
Greenland ice core North Greenland |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-8-1801-2014 https://tc.copernicus.org/articles/8/1801/2014/ |
op_doi |
https://doi.org/10.5194/tc-8-1801-2014 |
container_title |
The Cryosphere |
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8 |
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5 |
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1801 |
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1806 |
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1766015583212535808 |