Air mixing in firn and the age of the air at pore close-off
The air trapped in the bubbles of natural ice is not the same age as the surrounding ice. This is due to the fact that the air is enclosed in isolated bubbles only at the depth of the firn–ice transition. Within the overlying porous firn layer the air is able to mix and to exchange to a certain degr...
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International Glaciological Society
1988
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Online Access: | https://boris.unibe.ch/158757/1/schwander88ag.pdf https://boris.unibe.ch/158757/ |
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ftunivbern:oai:boris.unibe.ch:158757 2023-08-20T03:59:48+02:00 Air mixing in firn and the age of the air at pore close-off Schwander, J. Stauffer, B. Sigg, A. 1988 application/pdf https://boris.unibe.ch/158757/1/schwander88ag.pdf https://boris.unibe.ch/158757/ eng eng International Glaciological Society https://boris.unibe.ch/158757/ info:eu-repo/semantics/restrictedAccess Schwander, J.; Stauffer, B.; Sigg, A. (1988). Air mixing in firn and the age of the air at pore close-off. Annals of glaciology, 10, pp. 141-145. International Glaciological Society 10.3189/S0260305500004328 <http://dx.doi.org/10.3189/S0260305500004328> 530 Physics info:eu-repo/semantics/conferenceObject info:eu-repo/semantics/publishedVersion PeerReviewed 1988 ftunivbern https://doi.org/10.3189/S0260305500004328 2023-07-31T22:08:19Z The air trapped in the bubbles of natural ice is not the same age as the surrounding ice. This is due to the fact that the air is enclosed in isolated bubbles only at the depth of the firn–ice transition. Within the overlying porous firn layer the air is able to mix and to exchange to a certain degree with the atmosphere. The age difference between ice and air is given by the age of the ice at pore close-off, less the mixing delay. Also, there is an age distribution due to diffusive smoothing and due to the gradual enclosure of the air at the firn–ice transition. Knowledge of this age relation is necessary for the interpretation of climatic parameters measured on ice cores. This work concentrates on the effect of diffusive mixing. We report on measurements of the diffusivity of CO2 and O2 (in N2) in firn samples from Siple Station, Antarctica. It is shown that the dominant mixing process is molecular diffusion. The diffusion coefficient depends approximately linearly on the porosity. A one-dimensional diffusion model has been used to calculate the air mixing in firn at Siple Station (Antarctica), at the South Pole, and at Station Crête (Greenland). An exchange time of between 10 and 50 years is obtained. Conference Object Annals of Glaciology Antarc* Antarctica Greenland South pole South pole BORIS (Bern Open Repository and Information System, University of Bern) Greenland Siple ENVELOPE(-83.917,-83.917,-75.917,-75.917) South Pole Annals of Glaciology 10 141 145 |
institution |
Open Polar |
collection |
BORIS (Bern Open Repository and Information System, University of Bern) |
op_collection_id |
ftunivbern |
language |
English |
topic |
530 Physics |
spellingShingle |
530 Physics Schwander, J. Stauffer, B. Sigg, A. Air mixing in firn and the age of the air at pore close-off |
topic_facet |
530 Physics |
description |
The air trapped in the bubbles of natural ice is not the same age as the surrounding ice. This is due to the fact that the air is enclosed in isolated bubbles only at the depth of the firn–ice transition. Within the overlying porous firn layer the air is able to mix and to exchange to a certain degree with the atmosphere. The age difference between ice and air is given by the age of the ice at pore close-off, less the mixing delay. Also, there is an age distribution due to diffusive smoothing and due to the gradual enclosure of the air at the firn–ice transition. Knowledge of this age relation is necessary for the interpretation of climatic parameters measured on ice cores. This work concentrates on the effect of diffusive mixing. We report on measurements of the diffusivity of CO2 and O2 (in N2) in firn samples from Siple Station, Antarctica. It is shown that the dominant mixing process is molecular diffusion. The diffusion coefficient depends approximately linearly on the porosity. A one-dimensional diffusion model has been used to calculate the air mixing in firn at Siple Station (Antarctica), at the South Pole, and at Station Crête (Greenland). An exchange time of between 10 and 50 years is obtained. |
format |
Conference Object |
author |
Schwander, J. Stauffer, B. Sigg, A. |
author_facet |
Schwander, J. Stauffer, B. Sigg, A. |
author_sort |
Schwander, J. |
title |
Air mixing in firn and the age of the air at pore close-off |
title_short |
Air mixing in firn and the age of the air at pore close-off |
title_full |
Air mixing in firn and the age of the air at pore close-off |
title_fullStr |
Air mixing in firn and the age of the air at pore close-off |
title_full_unstemmed |
Air mixing in firn and the age of the air at pore close-off |
title_sort |
air mixing in firn and the age of the air at pore close-off |
publisher |
International Glaciological Society |
publishDate |
1988 |
url |
https://boris.unibe.ch/158757/1/schwander88ag.pdf https://boris.unibe.ch/158757/ |
long_lat |
ENVELOPE(-83.917,-83.917,-75.917,-75.917) |
geographic |
Greenland Siple South Pole |
geographic_facet |
Greenland Siple South Pole |
genre |
Annals of Glaciology Antarc* Antarctica Greenland South pole South pole |
genre_facet |
Annals of Glaciology Antarc* Antarctica Greenland South pole South pole |
op_source |
Schwander, J.; Stauffer, B.; Sigg, A. (1988). Air mixing in firn and the age of the air at pore close-off. Annals of glaciology, 10, pp. 141-145. International Glaciological Society 10.3189/S0260305500004328 <http://dx.doi.org/10.3189/S0260305500004328> |
op_relation |
https://boris.unibe.ch/158757/ |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.3189/S0260305500004328 |
container_title |
Annals of Glaciology |
container_volume |
10 |
container_start_page |
141 |
op_container_end_page |
145 |
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1774715726470316032 |