Gas Diffusivity and Permeability Through the Firn Column at Summit, Greenland: Measurements and Comparison to Microstructural Properties
The physical structure of polar firn plays a key role in the mechanisms by which glaciers and ice sheets preserve a natural archive of past atmospheric composition. This study presents the first measurements of gas diffusivity and permeability along with microstructural information measured from the...
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ftdartmouthcoll:oai:digitalcommons.dartmouth.edu:facoa-3318 2023-07-16T03:58:46+02:00 Gas Diffusivity and Permeability Through the Firn Column at Summit, Greenland: Measurements and Comparison to Microstructural Properties Adolph, A. C. C Albert, M. R 2014-02-28T08:00:00Z application/pdf https://digitalcommons.dartmouth.edu/facoa/2314 https://doi.org/10.5194/tc-8-319-2014 https://digitalcommons.dartmouth.edu/context/facoa/article/3318/viewcontent/tc_8_319_2014.pdf unknown Dartmouth Digital Commons https://digitalcommons.dartmouth.edu/facoa/2314 doi:10.5194/tc-8-319-2014 https://digitalcommons.dartmouth.edu/context/facoa/article/3318/viewcontent/tc_8_319_2014.pdf Dartmouth Scholarship Earth Sciences Glaciology Physical Sciences and Mathematics text 2014 ftdartmouthcoll https://doi.org/10.5194/tc-8-319-2014 2023-06-28T10:38:26Z The physical structure of polar firn plays a key role in the mechanisms by which glaciers and ice sheets preserve a natural archive of past atmospheric composition. This study presents the first measurements of gas diffusivity and permeability along with microstructural information measured from the near-surface firn through the firn column to pore close-off. Both fine- and coarse-grained firn from Summit, Greenland are included in this study to investigate the variability in firn caused by seasonal and storm-event layering. Our measurements reveal that the porosity of firn (derived from density) is insufficient to describe the full profiles of diffusivity and permeability, particularly at porosity values above 0.5. Thus, even a model that could perfectly predict the density profile would be insufficient for application to issues involving gas transport. The measured diffusivity profile presented here is compared to two diffusivity profiles modeled from firn air measurements from Summit. Because of differences in scale and in firn processes between the true field situation, firn modeling, and laboratory measurements, the results follow a similar overall pattern but do not align; our results constitute a lower bound on diffusive transport. In comparing our measurements of both diffusivity and permeability to previous parameterizations from numerical 3-D lattice-Boltzmann modeling, it is evident that the previous relationships to porosity are likely site-specific. We present parameterizations relating diffusivity and permeability to porosity as a possible tool, though use of direct measurements would be far more accurate when feasible. The relationships between gas transport properties and microstructural properties are characterized and compared to existing relationships for general porous media, specifically the Katz–Thompson (KT), Kozeny–Carman (KC), and Archie's law approximations. While those approximations can capture the general trend of gas transport relationships, they result in high errors for individual ... Text Greenland Dartmouth Digital Commons (Dartmouth College) Greenland The Cryosphere 8 1 319 328 |
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Open Polar |
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Dartmouth Digital Commons (Dartmouth College) |
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ftdartmouthcoll |
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unknown |
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Earth Sciences Glaciology Physical Sciences and Mathematics |
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Earth Sciences Glaciology Physical Sciences and Mathematics Adolph, A. C. C Albert, M. R Gas Diffusivity and Permeability Through the Firn Column at Summit, Greenland: Measurements and Comparison to Microstructural Properties |
topic_facet |
Earth Sciences Glaciology Physical Sciences and Mathematics |
description |
The physical structure of polar firn plays a key role in the mechanisms by which glaciers and ice sheets preserve a natural archive of past atmospheric composition. This study presents the first measurements of gas diffusivity and permeability along with microstructural information measured from the near-surface firn through the firn column to pore close-off. Both fine- and coarse-grained firn from Summit, Greenland are included in this study to investigate the variability in firn caused by seasonal and storm-event layering. Our measurements reveal that the porosity of firn (derived from density) is insufficient to describe the full profiles of diffusivity and permeability, particularly at porosity values above 0.5. Thus, even a model that could perfectly predict the density profile would be insufficient for application to issues involving gas transport. The measured diffusivity profile presented here is compared to two diffusivity profiles modeled from firn air measurements from Summit. Because of differences in scale and in firn processes between the true field situation, firn modeling, and laboratory measurements, the results follow a similar overall pattern but do not align; our results constitute a lower bound on diffusive transport. In comparing our measurements of both diffusivity and permeability to previous parameterizations from numerical 3-D lattice-Boltzmann modeling, it is evident that the previous relationships to porosity are likely site-specific. We present parameterizations relating diffusivity and permeability to porosity as a possible tool, though use of direct measurements would be far more accurate when feasible. The relationships between gas transport properties and microstructural properties are characterized and compared to existing relationships for general porous media, specifically the Katz–Thompson (KT), Kozeny–Carman (KC), and Archie's law approximations. While those approximations can capture the general trend of gas transport relationships, they result in high errors for individual ... |
format |
Text |
author |
Adolph, A. C. C Albert, M. R |
author_facet |
Adolph, A. C. C Albert, M. R |
author_sort |
Adolph, A. C. C |
title |
Gas Diffusivity and Permeability Through the Firn Column at Summit, Greenland: Measurements and Comparison to Microstructural Properties |
title_short |
Gas Diffusivity and Permeability Through the Firn Column at Summit, Greenland: Measurements and Comparison to Microstructural Properties |
title_full |
Gas Diffusivity and Permeability Through the Firn Column at Summit, Greenland: Measurements and Comparison to Microstructural Properties |
title_fullStr |
Gas Diffusivity and Permeability Through the Firn Column at Summit, Greenland: Measurements and Comparison to Microstructural Properties |
title_full_unstemmed |
Gas Diffusivity and Permeability Through the Firn Column at Summit, Greenland: Measurements and Comparison to Microstructural Properties |
title_sort |
gas diffusivity and permeability through the firn column at summit, greenland: measurements and comparison to microstructural properties |
publisher |
Dartmouth Digital Commons |
publishDate |
2014 |
url |
https://digitalcommons.dartmouth.edu/facoa/2314 https://doi.org/10.5194/tc-8-319-2014 https://digitalcommons.dartmouth.edu/context/facoa/article/3318/viewcontent/tc_8_319_2014.pdf |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
Dartmouth Scholarship |
op_relation |
https://digitalcommons.dartmouth.edu/facoa/2314 doi:10.5194/tc-8-319-2014 https://digitalcommons.dartmouth.edu/context/facoa/article/3318/viewcontent/tc_8_319_2014.pdf |
op_doi |
https://doi.org/10.5194/tc-8-319-2014 |
container_title |
The Cryosphere |
container_volume |
8 |
container_issue |
1 |
container_start_page |
319 |
op_container_end_page |
328 |
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1771546053897617408 |