The age of the air in the firn and the ice at Summit, Greenland
In the framework of the Eurocore drilling project 1989 at Summit, Central Greenland, air samples were collected from a drill hole in the firn at several depth levels. The samples have been analyzed for 85Kr, CO2, CH4, CFC's (F-11 and F-12) contents and for the isotopic composition of nitrogen a...
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1993
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ftdatacite:10.48350/158714 2023-05-15T16:27:58+02:00 The age of the air in the firn and the ice at Summit, Greenland Schwander, J. Barnola, J.-M. Andrié, C. Leuenberger, M. Ludin, A. Raynaud, D. Stauffer, B. 1993 https://dx.doi.org/10.48350/158714 https://boris.unibe.ch/158714/ unknown American Geophysical Union open access publisher holds copyright http://purl.org/coar/access_right/c_abf2 530 Physics Text article-journal journal article ScholarlyArticle 1993 ftdatacite https://doi.org/10.48350/158714 2021-11-05T12:55:41Z In the framework of the Eurocore drilling project 1989 at Summit, Central Greenland, air samples were collected from a drill hole in the firn at several depth levels. The samples have been analyzed for 85Kr, CO2, CH4, CFC's (F-11 and F-12) contents and for the isotopic composition of nitrogen and oxygen. The measured data are compared with the results of a diffusion model. CO2, for example, takes 12 years (with a standard deviation of 7.5 years) to diffuse from the surface to the firn-ice transition under the present climatic conditions at Summit. The difference between the age of the ice and the mean age of the occluded air is approximately 210 years. An enrichment of the heavier isotopes due to separation by gravity has been observed. Molecular diffusion alone suffices to explain the observed concentration trends in the firn column. We can, however, not exclude the existence of a convective zone below the surface. We have also measured the density and closed porosity along the firn core that has been retrieved when drilling the hole. The porosity data reveal that the air is occluded into bubbles mainly between 65 and 80 m, corresponding to densities of 790 and 830 kg/m3, respectively. Text Greenland DataCite Metadata Store (German National Library of Science and Technology) Greenland |
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530 Physics |
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530 Physics Schwander, J. Barnola, J.-M. Andrié, C. Leuenberger, M. Ludin, A. Raynaud, D. Stauffer, B. The age of the air in the firn and the ice at Summit, Greenland |
topic_facet |
530 Physics |
description |
In the framework of the Eurocore drilling project 1989 at Summit, Central Greenland, air samples were collected from a drill hole in the firn at several depth levels. The samples have been analyzed for 85Kr, CO2, CH4, CFC's (F-11 and F-12) contents and for the isotopic composition of nitrogen and oxygen. The measured data are compared with the results of a diffusion model. CO2, for example, takes 12 years (with a standard deviation of 7.5 years) to diffuse from the surface to the firn-ice transition under the present climatic conditions at Summit. The difference between the age of the ice and the mean age of the occluded air is approximately 210 years. An enrichment of the heavier isotopes due to separation by gravity has been observed. Molecular diffusion alone suffices to explain the observed concentration trends in the firn column. We can, however, not exclude the existence of a convective zone below the surface. We have also measured the density and closed porosity along the firn core that has been retrieved when drilling the hole. The porosity data reveal that the air is occluded into bubbles mainly between 65 and 80 m, corresponding to densities of 790 and 830 kg/m3, respectively. |
format |
Text |
author |
Schwander, J. Barnola, J.-M. Andrié, C. Leuenberger, M. Ludin, A. Raynaud, D. Stauffer, B. |
author_facet |
Schwander, J. Barnola, J.-M. Andrié, C. Leuenberger, M. Ludin, A. Raynaud, D. Stauffer, B. |
author_sort |
Schwander, J. |
title |
The age of the air in the firn and the ice at Summit, Greenland |
title_short |
The age of the air in the firn and the ice at Summit, Greenland |
title_full |
The age of the air in the firn and the ice at Summit, Greenland |
title_fullStr |
The age of the air in the firn and the ice at Summit, Greenland |
title_full_unstemmed |
The age of the air in the firn and the ice at Summit, Greenland |
title_sort |
age of the air in the firn and the ice at summit, greenland |
publisher |
American Geophysical Union |
publishDate |
1993 |
url |
https://dx.doi.org/10.48350/158714 https://boris.unibe.ch/158714/ |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_rights |
open access publisher holds copyright http://purl.org/coar/access_right/c_abf2 |
op_doi |
https://doi.org/10.48350/158714 |
_version_ |
1766017584593895424 |