Observing and modeling the influence of layering on bubble trapping in polar firn
Interpretation of ice core trace gas records depends on an accurate understanding of the processes that smooth the atmospheric signal in the firn. Much work has been done to understand the processes affecting air transport in the open pores of the firn, but a paucity of data from air trapped in bubb...
Published in: | Journal of Geophysical Research: Atmospheres |
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2015
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Online Access: | https://escholarship.org/uc/item/5hd92964 https://escholarship.org/content/qt5hd92964/qt5hd92964.pdf https://doi.org/10.1002/2014jd022766 |
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ftcdlib:oai:escholarship.org:ark:/13030/qt5hd92964 2024-09-15T17:44:42+00:00 Observing and modeling the influence of layering on bubble trapping in polar firn Mitchell, Logan E Buizert, Christo Brook, Edward J Breton, Daniel J Fegyveresi, John Baggenstos, Daniel Orsi, Anais Severinghaus, Jeffrey Alley, Richard B Albert, Mary Rhodes, Rachael H McConnell, Joseph R Sigl, Michael Maselli, Olivia Gregory, Stephanie Ahn, Jinho 2558 - 2574 2015-03-27 application/pdf https://escholarship.org/uc/item/5hd92964 https://escholarship.org/content/qt5hd92964/qt5hd92964.pdf https://doi.org/10.1002/2014jd022766 unknown eScholarship, University of California qt5hd92964 https://escholarship.org/uc/item/5hd92964 https://escholarship.org/content/qt5hd92964/qt5hd92964.pdf doi:10.1002/2014jd022766 public Journal of Geophysical Research: Atmospheres, vol 120, iss 6 Climate Action firn layering ice core methane firn density total air content Atmospheric Sciences Physical Geography and Environmental Geoscience article 2015 ftcdlib https://doi.org/10.1002/2014jd022766 2024-06-28T06:28:20Z Interpretation of ice core trace gas records depends on an accurate understanding of the processes that smooth the atmospheric signal in the firn. Much work has been done to understand the processes affecting air transport in the open pores of the firn, but a paucity of data from air trapped in bubbles in the firn-ice transition region has limited the ability to constrain the effect of bubble closure processes. Here we present high-resolution measurements of firn density, methane concentrations, nitrogen isotopes, and total air content that show layering in the firn-ice transition region at the West Antarctic Ice Sheet (WAIS) Divide ice core site. Using the notion that bubble trapping is a stochastic process, we derive a new parameterization for closed porosity that incorporates the effects of layering in a steady state firn modeling approach. We include the process of bubble trapping into an open-porosity firn air transport model and obtain a good fit to the firn core data. We find that layering broadens the depth range over which bubbles are trapped, widens the modeled gas age distribution of air in closed bubbles, reduces the mean gas age of air in closed bubbles, and introduces stratigraphic irregularities in the gas age scale that have a peak-to-peak variability of ~10 years at WAIS Divide. For a more complete understanding of gas occlusion and its impact on ice core records, we suggest that this experiment be repeated at sites climatically different from WAIS Divide, for example, on the East Antarctic plateau. Article in Journal/Newspaper Antarc* Antarctic ice core Ice Sheet University of California: eScholarship Journal of Geophysical Research: Atmospheres 120 6 2558 2574 |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
unknown |
topic |
Climate Action firn layering ice core methane firn density total air content Atmospheric Sciences Physical Geography and Environmental Geoscience |
spellingShingle |
Climate Action firn layering ice core methane firn density total air content Atmospheric Sciences Physical Geography and Environmental Geoscience Mitchell, Logan E Buizert, Christo Brook, Edward J Breton, Daniel J Fegyveresi, John Baggenstos, Daniel Orsi, Anais Severinghaus, Jeffrey Alley, Richard B Albert, Mary Rhodes, Rachael H McConnell, Joseph R Sigl, Michael Maselli, Olivia Gregory, Stephanie Ahn, Jinho Observing and modeling the influence of layering on bubble trapping in polar firn |
topic_facet |
Climate Action firn layering ice core methane firn density total air content Atmospheric Sciences Physical Geography and Environmental Geoscience |
description |
Interpretation of ice core trace gas records depends on an accurate understanding of the processes that smooth the atmospheric signal in the firn. Much work has been done to understand the processes affecting air transport in the open pores of the firn, but a paucity of data from air trapped in bubbles in the firn-ice transition region has limited the ability to constrain the effect of bubble closure processes. Here we present high-resolution measurements of firn density, methane concentrations, nitrogen isotopes, and total air content that show layering in the firn-ice transition region at the West Antarctic Ice Sheet (WAIS) Divide ice core site. Using the notion that bubble trapping is a stochastic process, we derive a new parameterization for closed porosity that incorporates the effects of layering in a steady state firn modeling approach. We include the process of bubble trapping into an open-porosity firn air transport model and obtain a good fit to the firn core data. We find that layering broadens the depth range over which bubbles are trapped, widens the modeled gas age distribution of air in closed bubbles, reduces the mean gas age of air in closed bubbles, and introduces stratigraphic irregularities in the gas age scale that have a peak-to-peak variability of ~10 years at WAIS Divide. For a more complete understanding of gas occlusion and its impact on ice core records, we suggest that this experiment be repeated at sites climatically different from WAIS Divide, for example, on the East Antarctic plateau. |
format |
Article in Journal/Newspaper |
author |
Mitchell, Logan E Buizert, Christo Brook, Edward J Breton, Daniel J Fegyveresi, John Baggenstos, Daniel Orsi, Anais Severinghaus, Jeffrey Alley, Richard B Albert, Mary Rhodes, Rachael H McConnell, Joseph R Sigl, Michael Maselli, Olivia Gregory, Stephanie Ahn, Jinho |
author_facet |
Mitchell, Logan E Buizert, Christo Brook, Edward J Breton, Daniel J Fegyveresi, John Baggenstos, Daniel Orsi, Anais Severinghaus, Jeffrey Alley, Richard B Albert, Mary Rhodes, Rachael H McConnell, Joseph R Sigl, Michael Maselli, Olivia Gregory, Stephanie Ahn, Jinho |
author_sort |
Mitchell, Logan E |
title |
Observing and modeling the influence of layering on bubble trapping in polar firn |
title_short |
Observing and modeling the influence of layering on bubble trapping in polar firn |
title_full |
Observing and modeling the influence of layering on bubble trapping in polar firn |
title_fullStr |
Observing and modeling the influence of layering on bubble trapping in polar firn |
title_full_unstemmed |
Observing and modeling the influence of layering on bubble trapping in polar firn |
title_sort |
observing and modeling the influence of layering on bubble trapping in polar firn |
publisher |
eScholarship, University of California |
publishDate |
2015 |
url |
https://escholarship.org/uc/item/5hd92964 https://escholarship.org/content/qt5hd92964/qt5hd92964.pdf https://doi.org/10.1002/2014jd022766 |
op_coverage |
2558 - 2574 |
genre |
Antarc* Antarctic ice core Ice Sheet |
genre_facet |
Antarc* Antarctic ice core Ice Sheet |
op_source |
Journal of Geophysical Research: Atmospheres, vol 120, iss 6 |
op_relation |
qt5hd92964 https://escholarship.org/uc/item/5hd92964 https://escholarship.org/content/qt5hd92964/qt5hd92964.pdf doi:10.1002/2014jd022766 |
op_rights |
public |
op_doi |
https://doi.org/10.1002/2014jd022766 |
container_title |
Journal of Geophysical Research: Atmospheres |
container_volume |
120 |
container_issue |
6 |
container_start_page |
2558 |
op_container_end_page |
2574 |
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1810492355355082752 |