Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ15N 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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ftdatacite:10.7892/boris.47314 2023-05-15T13:54:54+02:00 Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ15N measurements Parrenin, F. Landais, A. Debret, M. Mulvaney, R. Capron, E. Jouzel, J. Leuenberger, Markus Buiron, D. Chappellaz, J. Martinerie, P. Masson-Delmotte, V. Cauquoin, A. Prié, F. 2013 application/pdf https://dx.doi.org/10.7892/boris.47314 http://boris.unibe.ch/47314/ en eng Copernicus Publications info:eu-repo/semantics/openAccess 530 Physics CreativeWork article 2013 ftdatacite https://doi.org/10.7892/boris.47314 2021-11-05T12:55:41Z 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 δ15N of N2 in air trapped in ice core, assuming that δ15N 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-δ15N measurements from the EPICA Dome C (EDC) site, the studied regions encompass a large range of surface accumulation rates and temperature conditions. Our δ15N profiles reveal a heterogeneous response of the firn structure to glacial–interglacial climatic changes. While firn densification simulations correctly predict TALDICE δ15N variations, they systematically fail to capture the large millennial-scale δ15N variations measured at BI and the δ15N 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–δ15N 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 δ15N 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 DataCite Metadata Store (German National Library of Science and Technology) Antarctic Dronning Maud Land Ross Island Berkner Island ENVELOPE(-48.117,-48.117,-79.333,-79.333) |
institution |
Open Polar |
collection |
DataCite Metadata Store (German National Library of Science and Technology) |
op_collection_id |
ftdatacite |
language |
English |
topic |
530 Physics |
spellingShingle |
530 Physics Parrenin, F. Landais, A. Debret, M. Mulvaney, R. Capron, E. Jouzel, J. Leuenberger, Markus Buiron, D. Chappellaz, J. Martinerie, P. Masson-Delmotte, V. Cauquoin, A. Prié, F. Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ15N measurements |
topic_facet |
530 Physics |
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 δ15N of N2 in air trapped in ice core, assuming that δ15N 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-δ15N measurements from the EPICA Dome C (EDC) site, the studied regions encompass a large range of surface accumulation rates and temperature conditions. Our δ15N profiles reveal a heterogeneous response of the firn structure to glacial–interglacial climatic changes. While firn densification simulations correctly predict TALDICE δ15N variations, they systematically fail to capture the large millennial-scale δ15N variations measured at BI and the δ15N 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–δ15N 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 δ15N 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 |
Parrenin, F. Landais, A. Debret, M. Mulvaney, R. Capron, E. Jouzel, J. Leuenberger, Markus Buiron, D. Chappellaz, J. Martinerie, P. Masson-Delmotte, V. Cauquoin, A. Prié, F. |
author_facet |
Parrenin, F. Landais, A. Debret, M. Mulvaney, R. Capron, E. Jouzel, J. Leuenberger, Markus Buiron, D. Chappellaz, J. Martinerie, P. Masson-Delmotte, V. Cauquoin, A. Prié, F. |
author_sort |
Parrenin, F. |
title |
Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ15N measurements |
title_short |
Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ15N measurements |
title_full |
Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ15N measurements |
title_fullStr |
Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ15N measurements |
title_full_unstemmed |
Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ15N measurements |
title_sort |
glacial–interglacial dynamics of antarctic firn columns: comparison between simulations and ice core air-δ15n measurements |
publisher |
Copernicus Publications |
publishDate |
2013 |
url |
https://dx.doi.org/10.7892/boris.47314 http://boris.unibe.ch/47314/ |
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_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.7892/boris.47314 |
_version_ |
1766261101575536640 |