Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ 15 N measurements
Correct estimation of the firn lock-in depth is essential for correctly linking gas and ice chronologies in ice core studies. Here, two approaches to constrain the firn depth evolution in Antarctica are presented over the last deglaciation: outputs of a firn densification model, and measurements of...
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ftdoajarticles:oai:doaj.org/article:75f3cfcb8b934237ab5b07b28f489629 2023-05-15T13:49:20+02:00 Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ 15 N measurements E. Capron A. Landais D. Buiron A. Cauquoin J. Chappellaz M. Debret J. Jouzel M. Leuenberger P. Martinerie V. Masson-Delmotte R. Mulvaney F. Parrenin F. Prié 2013-05-01T00:00:00Z https://doi.org/10.5194/cp-9-983-2013 https://doaj.org/article/75f3cfcb8b934237ab5b07b28f489629 EN eng Copernicus Publications http://www.clim-past.net/9/983/2013/cp-9-983-2013.pdf https://doaj.org/toc/1814-9324 https://doaj.org/toc/1814-9332 doi:10.5194/cp-9-983-2013 1814-9324 1814-9332 https://doaj.org/article/75f3cfcb8b934237ab5b07b28f489629 Climate of the Past, Vol 9, Iss 3, Pp 983-999 (2013) Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 article 2013 ftdoajarticles https://doi.org/10.5194/cp-9-983-2013 2022-12-31T02:24:03Z Correct estimation of the firn lock-in depth is essential for correctly linking gas and ice chronologies in ice core studies. Here, two approaches to constrain the firn depth evolution in Antarctica are presented over the last deglaciation: outputs of a firn densification model, and measurements of δ 15 N of N 2 in air trapped in ice core, assuming that δ 15 N is only affected by gravitational fractionation in the firn column. Since the firn densification process is largely governed by surface temperature and accumulation rate, we have investigated four ice cores drilled in coastal (Berkner Island, BI, and James Ross Island, JRI) and semi-coastal (TALDICE and EPICA Dronning Maud Land, EDML) Antarctic regions. Combined with available ice core air-δ 15 N measurements from the EPICA Dome C (EDC) site, the studied regions encompass a large range of surface accumulation rates and temperature conditions. Our δ 15 N profiles reveal a heterogeneous response of the firn structure to glacial–interglacial climatic changes. While firn densification simulations correctly predict TALDICE δ 15 N variations, they systematically fail to capture the large millennial-scale δ 15 N variations measured at BI and the δ 15 N glacial levels measured at JRI and EDML – a mismatch previously reported for central East Antarctic ice cores. New constraints of the EDML gas–ice depth offset during the Laschamp event (~41 ka) and the last deglaciation do not favour the hypothesis of a large convective zone within the firn as the explanation of the glacial firn model–δ 15 N data mismatch for this site. While we could not conduct an in-depth study of the influence of impurities in snow for firnification from the existing datasets, our detailed comparison between the δ 15 N profiles and firn model simulations under different temperature and accumulation rate scenarios suggests that the role of accumulation rate may have been underestimated in the current description of firnification models. Article in Journal/Newspaper Antarc* Antarctic Antarctica Berkner Island Dronning Maud Land EPICA ice core James Ross Island Ross Island Directory of Open Access Journals: DOAJ Articles Antarctic Dronning Maud Land Ross Island Berkner Island ENVELOPE(-48.117,-48.117,-79.333,-79.333) Climate of the Past 9 3 983 999 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 |
spellingShingle |
Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 E. Capron A. Landais D. Buiron A. Cauquoin J. Chappellaz M. Debret J. Jouzel M. Leuenberger P. Martinerie V. Masson-Delmotte R. Mulvaney F. Parrenin F. Prié Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ 15 N measurements |
topic_facet |
Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 |
description |
Correct estimation of the firn lock-in depth is essential for correctly linking gas and ice chronologies in ice core studies. Here, two approaches to constrain the firn depth evolution in Antarctica are presented over the last deglaciation: outputs of a firn densification model, and measurements of δ 15 N of N 2 in air trapped in ice core, assuming that δ 15 N is only affected by gravitational fractionation in the firn column. Since the firn densification process is largely governed by surface temperature and accumulation rate, we have investigated four ice cores drilled in coastal (Berkner Island, BI, and James Ross Island, JRI) and semi-coastal (TALDICE and EPICA Dronning Maud Land, EDML) Antarctic regions. Combined with available ice core air-δ 15 N measurements from the EPICA Dome C (EDC) site, the studied regions encompass a large range of surface accumulation rates and temperature conditions. Our δ 15 N profiles reveal a heterogeneous response of the firn structure to glacial–interglacial climatic changes. While firn densification simulations correctly predict TALDICE δ 15 N variations, they systematically fail to capture the large millennial-scale δ 15 N variations measured at BI and the δ 15 N glacial levels measured at JRI and EDML – a mismatch previously reported for central East Antarctic ice cores. New constraints of the EDML gas–ice depth offset during the Laschamp event (~41 ka) and the last deglaciation do not favour the hypothesis of a large convective zone within the firn as the explanation of the glacial firn model–δ 15 N data mismatch for this site. While we could not conduct an in-depth study of the influence of impurities in snow for firnification from the existing datasets, our detailed comparison between the δ 15 N profiles and firn model simulations under different temperature and accumulation rate scenarios suggests that the role of accumulation rate may have been underestimated in the current description of firnification models. |
format |
Article in Journal/Newspaper |
author |
E. Capron A. Landais D. Buiron A. Cauquoin J. Chappellaz M. Debret J. Jouzel M. Leuenberger P. Martinerie V. Masson-Delmotte R. Mulvaney F. Parrenin F. Prié |
author_facet |
E. Capron A. Landais D. Buiron A. Cauquoin J. Chappellaz M. Debret J. Jouzel M. Leuenberger P. Martinerie V. Masson-Delmotte R. Mulvaney F. Parrenin F. Prié |
author_sort |
E. Capron |
title |
Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ 15 N measurements |
title_short |
Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ 15 N measurements |
title_full |
Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ 15 N measurements |
title_fullStr |
Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ 15 N measurements |
title_full_unstemmed |
Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ 15 N measurements |
title_sort |
glacial–interglacial dynamics of antarctic firn columns: comparison between simulations and ice core air-δ 15 n measurements |
publisher |
Copernicus Publications |
publishDate |
2013 |
url |
https://doi.org/10.5194/cp-9-983-2013 https://doaj.org/article/75f3cfcb8b934237ab5b07b28f489629 |
long_lat |
ENVELOPE(-48.117,-48.117,-79.333,-79.333) |
geographic |
Antarctic Dronning Maud Land Ross Island Berkner Island |
geographic_facet |
Antarctic Dronning Maud Land Ross Island Berkner Island |
genre |
Antarc* Antarctic Antarctica Berkner Island Dronning Maud Land EPICA ice core James Ross Island Ross Island |
genre_facet |
Antarc* Antarctic Antarctica Berkner Island Dronning Maud Land EPICA ice core James Ross Island Ross Island |
op_source |
Climate of the Past, Vol 9, Iss 3, Pp 983-999 (2013) |
op_relation |
http://www.clim-past.net/9/983/2013/cp-9-983-2013.pdf https://doaj.org/toc/1814-9324 https://doaj.org/toc/1814-9332 doi:10.5194/cp-9-983-2013 1814-9324 1814-9332 https://doaj.org/article/75f3cfcb8b934237ab5b07b28f489629 |
op_doi |
https://doi.org/10.5194/cp-9-983-2013 |
container_title |
Climate of the Past |
container_volume |
9 |
container_issue |
3 |
container_start_page |
983 |
op_container_end_page |
999 |
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1766251184869343232 |