Model calculations of the age of firn air across the Antarctic continent
The age of firn air in Antarctica at pore close-off depth is only known for a few specific sites where firn air has been sampled for analyses. We present a model that calculates the age of firn air at pore close-off depth for the entire Antarctic continent. The model basically uses four meteorologic...
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2004
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00049241 2023-05-15T13:54:47+02:00 Model calculations of the age of firn air across the Antarctic continent Kaspers, K. A. van de Wal, R. S. W. van den Broeke, M. R. Schwander, J. van Lipzig, N. P. M. Brenninkmeijer, C. A. M. 2004-08 electronic https://doi.org/10.5194/acp-4-1365-2004 https://noa.gwlb.de/receive/cop_mods_00049241 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00048861/acp-4-1365-2004.pdf https://acp.copernicus.org/articles/4/1365/2004/acp-4-1365-2004.pdf eng eng Copernicus Publications Atmospheric Chemistry and Physics -- http://www.atmos-chem-phys.net/volumes_and_issues.html -- http://www.bibliothek.uni-regensburg.de/ezeit/?2069847 -- 1680-7324 https://doi.org/10.5194/acp-4-1365-2004 https://noa.gwlb.de/receive/cop_mods_00049241 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00048861/acp-4-1365-2004.pdf https://acp.copernicus.org/articles/4/1365/2004/acp-4-1365-2004.pdf https://open-access.net/ uneingeschränkt info:eu-repo/semantics/openAccess article Verlagsveröffentlichung article Text doc-type:article 2004 ftnonlinearchiv https://doi.org/10.5194/acp-4-1365-2004 2022-02-08T22:37:36Z The age of firn air in Antarctica at pore close-off depth is only known for a few specific sites where firn air has been sampled for analyses. We present a model that calculates the age of firn air at pore close-off depth for the entire Antarctic continent. The model basically uses four meteorological parameters as input (surface temperature, pressure, accumulation rate and wind speed). Using parameterisations for surface snow density, pore close-off density and tortuosity, in combination with a density-depth model and data of a regional atmospheric climate model, distribution of pore close-off depth for the entire Antarctic continent is determined. The deepest pore close-off depth was found for the East Antarctic Plateau near 72° E, 82° S, at 150±15 m (2σ). A firn air diffusion model was applied to calculate the age of CO2 at pore close-off depth. The results predict that the oldest firn gas (CO2 age) is located between Dome Fuji, Dome Argos and Vostok at 43° E, 78° S being 148±23 (1σ or 38 for 2σ) years old. At this location an atmospheric trace gas record should be obtained. In this study we show that methyl chloride could be recorded with a predicted length of 125 years as an example for trace gas records at this location. The longest record currently available from firn air is derived at South Pole, being 80 years. Sensitivity tests reveal that the locations with old firn air (East Antarctic Plateau) have an estimated uncertainty (2σ) for the modelled CO2 age at pore close-off depth of 30% and of about 40% for locations with younger firn air (CO2 age typically 40 years). Comparing the modelled age of CO2 at pore close-off depth with directly determined ages at seven sites yielded a correlation coefficient of 0.90 and a slope close to 1, suggesting a high level of confidence for the modelled results in spite of considerable remaining uncertainties. Article in Journal/Newspaper Antarc* Antarctic Antarctica South pole South pole Niedersächsisches Online-Archiv NOA Antarctic Dome Fuji ENVELOPE(39.700,39.700,-77.317,-77.317) South Pole The Antarctic Atmospheric Chemistry and Physics 4 5 1365 1380 |
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Niedersächsisches Online-Archiv NOA |
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ftnonlinearchiv |
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English |
topic |
article Verlagsveröffentlichung |
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article Verlagsveröffentlichung Kaspers, K. A. van de Wal, R. S. W. van den Broeke, M. R. Schwander, J. van Lipzig, N. P. M. Brenninkmeijer, C. A. M. Model calculations of the age of firn air across the Antarctic continent |
topic_facet |
article Verlagsveröffentlichung |
description |
The age of firn air in Antarctica at pore close-off depth is only known for a few specific sites where firn air has been sampled for analyses. We present a model that calculates the age of firn air at pore close-off depth for the entire Antarctic continent. The model basically uses four meteorological parameters as input (surface temperature, pressure, accumulation rate and wind speed). Using parameterisations for surface snow density, pore close-off density and tortuosity, in combination with a density-depth model and data of a regional atmospheric climate model, distribution of pore close-off depth for the entire Antarctic continent is determined. The deepest pore close-off depth was found for the East Antarctic Plateau near 72° E, 82° S, at 150±15 m (2σ). A firn air diffusion model was applied to calculate the age of CO2 at pore close-off depth. The results predict that the oldest firn gas (CO2 age) is located between Dome Fuji, Dome Argos and Vostok at 43° E, 78° S being 148±23 (1σ or 38 for 2σ) years old. At this location an atmospheric trace gas record should be obtained. In this study we show that methyl chloride could be recorded with a predicted length of 125 years as an example for trace gas records at this location. The longest record currently available from firn air is derived at South Pole, being 80 years. Sensitivity tests reveal that the locations with old firn air (East Antarctic Plateau) have an estimated uncertainty (2σ) for the modelled CO2 age at pore close-off depth of 30% and of about 40% for locations with younger firn air (CO2 age typically 40 years). Comparing the modelled age of CO2 at pore close-off depth with directly determined ages at seven sites yielded a correlation coefficient of 0.90 and a slope close to 1, suggesting a high level of confidence for the modelled results in spite of considerable remaining uncertainties. |
format |
Article in Journal/Newspaper |
author |
Kaspers, K. A. van de Wal, R. S. W. van den Broeke, M. R. Schwander, J. van Lipzig, N. P. M. Brenninkmeijer, C. A. M. |
author_facet |
Kaspers, K. A. van de Wal, R. S. W. van den Broeke, M. R. Schwander, J. van Lipzig, N. P. M. Brenninkmeijer, C. A. M. |
author_sort |
Kaspers, K. A. |
title |
Model calculations of the age of firn air across the Antarctic continent |
title_short |
Model calculations of the age of firn air across the Antarctic continent |
title_full |
Model calculations of the age of firn air across the Antarctic continent |
title_fullStr |
Model calculations of the age of firn air across the Antarctic continent |
title_full_unstemmed |
Model calculations of the age of firn air across the Antarctic continent |
title_sort |
model calculations of the age of firn air across the antarctic continent |
publisher |
Copernicus Publications |
publishDate |
2004 |
url |
https://doi.org/10.5194/acp-4-1365-2004 https://noa.gwlb.de/receive/cop_mods_00049241 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00048861/acp-4-1365-2004.pdf https://acp.copernicus.org/articles/4/1365/2004/acp-4-1365-2004.pdf |
long_lat |
ENVELOPE(39.700,39.700,-77.317,-77.317) |
geographic |
Antarctic Dome Fuji South Pole The Antarctic |
geographic_facet |
Antarctic Dome Fuji South Pole The Antarctic |
genre |
Antarc* Antarctic Antarctica South pole South pole |
genre_facet |
Antarc* Antarctic Antarctica South pole South pole |
op_relation |
Atmospheric Chemistry and Physics -- http://www.atmos-chem-phys.net/volumes_and_issues.html -- http://www.bibliothek.uni-regensburg.de/ezeit/?2069847 -- 1680-7324 https://doi.org/10.5194/acp-4-1365-2004 https://noa.gwlb.de/receive/cop_mods_00049241 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00048861/acp-4-1365-2004.pdf https://acp.copernicus.org/articles/4/1365/2004/acp-4-1365-2004.pdf |
op_rights |
https://open-access.net/ uneingeschränkt info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/acp-4-1365-2004 |
container_title |
Atmospheric Chemistry and Physics |
container_volume |
4 |
container_issue |
5 |
container_start_page |
1365 |
op_container_end_page |
1380 |
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1766260892207415296 |