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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ftdartmouthcoll:oai:digitalcommons.dartmouth.edu:facoa-3319 2023-07-16T03:58:41+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. 2014-10-01T07:00:00Z application/pdf https://digitalcommons.dartmouth.edu/facoa/2315 https://doi.org/10.5194/tc-8-1801-2014 https://digitalcommons.dartmouth.edu/context/facoa/article/3319/viewcontent/tc_8_1801_2014.pdf unknown Dartmouth Digital Commons https://digitalcommons.dartmouth.edu/facoa/2315 doi:10.5194/tc-8-1801-2014 https://digitalcommons.dartmouth.edu/context/facoa/article/3319/viewcontent/tc_8_1801_2014.pdf Dartmouth Scholarship Earth Sciences Glaciology Physical Sciences and Mathematics text 2014 ftdartmouthcoll https://doi.org/10.5194/tc-8-1801-2014 2023-06-28T10:43:47Z 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. Text Greenland ice core North Greenland Dartmouth Digital Commons (Dartmouth College) Greenland The Cryosphere 8 5 1801 1806 |
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Earth Sciences Glaciology Physical Sciences and Mathematics |
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Earth Sciences Glaciology Physical Sciences and Mathematics 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 |
topic_facet |
Earth Sciences Glaciology Physical Sciences and Mathematics |
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 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. |
format |
Text |
author |
Keegan, K. Albert, M. R Baker, I. |
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 |
publisher |
Dartmouth Digital Commons |
publishDate |
2014 |
url |
https://digitalcommons.dartmouth.edu/facoa/2315 https://doi.org/10.5194/tc-8-1801-2014 https://digitalcommons.dartmouth.edu/context/facoa/article/3319/viewcontent/tc_8_1801_2014.pdf |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland ice core North Greenland |
genre_facet |
Greenland ice core North Greenland |
op_source |
Dartmouth Scholarship |
op_relation |
https://digitalcommons.dartmouth.edu/facoa/2315 doi:10.5194/tc-8-1801-2014 https://digitalcommons.dartmouth.edu/context/facoa/article/3319/viewcontent/tc_8_1801_2014.pdf |
op_doi |
https://doi.org/10.5194/tc-8-1801-2014 |
container_title |
The Cryosphere |
container_volume |
8 |
container_issue |
5 |
container_start_page |
1801 |
op_container_end_page |
1806 |
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1771545942254682112 |