Estimation of gas record alteration in very low-accumulation ice cores
We measured the methane mixing ratios of enclosed air in five ice core sections drilled on the East Antarctic Plateau. Our work aims to study two effects that alter the recorded gas concentrations in ice cores: layered gas trapping artifacts and firn smoothing. Layered gas trapping artifacts are due...
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ftdoajarticles:oai:doaj.org/article:418ff0953ced400f83918d602b4354f6 2023-05-15T14:00:47+02:00 Estimation of gas record alteration in very low-accumulation ice cores K. Fourteau P. Martinerie X. Faïn A. A. Ekaykin J. Chappellaz V. Lipenkov 2020-03-01T00:00:00Z https://doi.org/10.5194/cp-16-503-2020 https://doaj.org/article/418ff0953ced400f83918d602b4354f6 EN eng Copernicus Publications https://www.clim-past.net/16/503/2020/cp-16-503-2020.pdf https://doaj.org/toc/1814-9324 https://doaj.org/toc/1814-9332 doi:10.5194/cp-16-503-2020 1814-9324 1814-9332 https://doaj.org/article/418ff0953ced400f83918d602b4354f6 Climate of the Past, Vol 16, Pp 503-522 (2020) Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 article 2020 ftdoajarticles https://doi.org/10.5194/cp-16-503-2020 2022-12-31T05:11:20Z We measured the methane mixing ratios of enclosed air in five ice core sections drilled on the East Antarctic Plateau. Our work aims to study two effects that alter the recorded gas concentrations in ice cores: layered gas trapping artifacts and firn smoothing. Layered gas trapping artifacts are due to the heterogeneous nature of polar firn, where some strata might close early and trap abnormally old gases that appear as spurious values during measurements. The smoothing is due to the combined effects of diffusive mixing in the firn and the progressive closure of bubbles at the bottom of the firn. Consequently, the gases trapped in a given ice layer span a distribution of ages. This means that the gas concentration in an ice layer is the average value over a certain period of time, which removes the fast variability from the record. Here, we focus on the study of East Antarctic Plateau ice cores, as these low-accumulation ice cores are particularly affected by both layering and smoothing. We use high-resolution methane data to test a simple trapping model reproducing the layered gas trapping artifacts for different accumulation conditions typical of the East Antarctic Plateau. We also use the high-resolution methane measurements to estimate the gas age distributions of the enclosed air in the five newly measured ice core sections. It appears that for accumulations below 2 cm ice equivalent yr −1 the gas records experience nearly the same degree of smoothing. We therefore propose to use a single gas age distribution to represent the firn smoothing observed in the glacial ice cores of the East Antarctic Plateau. Finally, we used the layered gas trapping model and the estimation of glacial firn smoothing to quantify their potential impacts on a hypothetical 1.5-million-year-old ice core from the East Antarctic Plateau. Our results indicate that layering artifacts are no longer individually resolved in the case of very thinned ice near the bedrock. They nonetheless contribute to slight biases of the measured signal ... Article in Journal/Newspaper Antarc* Antarctic ice core Directory of Open Access Journals: DOAJ Articles Antarctic Climate of the Past 16 2 503 522 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
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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 K. Fourteau P. Martinerie X. Faïn A. A. Ekaykin J. Chappellaz V. Lipenkov Estimation of gas record alteration in very low-accumulation ice cores |
topic_facet |
Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 |
description |
We measured the methane mixing ratios of enclosed air in five ice core sections drilled on the East Antarctic Plateau. Our work aims to study two effects that alter the recorded gas concentrations in ice cores: layered gas trapping artifacts and firn smoothing. Layered gas trapping artifacts are due to the heterogeneous nature of polar firn, where some strata might close early and trap abnormally old gases that appear as spurious values during measurements. The smoothing is due to the combined effects of diffusive mixing in the firn and the progressive closure of bubbles at the bottom of the firn. Consequently, the gases trapped in a given ice layer span a distribution of ages. This means that the gas concentration in an ice layer is the average value over a certain period of time, which removes the fast variability from the record. Here, we focus on the study of East Antarctic Plateau ice cores, as these low-accumulation ice cores are particularly affected by both layering and smoothing. We use high-resolution methane data to test a simple trapping model reproducing the layered gas trapping artifacts for different accumulation conditions typical of the East Antarctic Plateau. We also use the high-resolution methane measurements to estimate the gas age distributions of the enclosed air in the five newly measured ice core sections. It appears that for accumulations below 2 cm ice equivalent yr −1 the gas records experience nearly the same degree of smoothing. We therefore propose to use a single gas age distribution to represent the firn smoothing observed in the glacial ice cores of the East Antarctic Plateau. Finally, we used the layered gas trapping model and the estimation of glacial firn smoothing to quantify their potential impacts on a hypothetical 1.5-million-year-old ice core from the East Antarctic Plateau. Our results indicate that layering artifacts are no longer individually resolved in the case of very thinned ice near the bedrock. They nonetheless contribute to slight biases of the measured signal ... |
format |
Article in Journal/Newspaper |
author |
K. Fourteau P. Martinerie X. Faïn A. A. Ekaykin J. Chappellaz V. Lipenkov |
author_facet |
K. Fourteau P. Martinerie X. Faïn A. A. Ekaykin J. Chappellaz V. Lipenkov |
author_sort |
K. Fourteau |
title |
Estimation of gas record alteration in very low-accumulation ice cores |
title_short |
Estimation of gas record alteration in very low-accumulation ice cores |
title_full |
Estimation of gas record alteration in very low-accumulation ice cores |
title_fullStr |
Estimation of gas record alteration in very low-accumulation ice cores |
title_full_unstemmed |
Estimation of gas record alteration in very low-accumulation ice cores |
title_sort |
estimation of gas record alteration in very low-accumulation ice cores |
publisher |
Copernicus Publications |
publishDate |
2020 |
url |
https://doi.org/10.5194/cp-16-503-2020 https://doaj.org/article/418ff0953ced400f83918d602b4354f6 |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic ice core |
genre_facet |
Antarc* Antarctic ice core |
op_source |
Climate of the Past, Vol 16, Pp 503-522 (2020) |
op_relation |
https://www.clim-past.net/16/503/2020/cp-16-503-2020.pdf https://doaj.org/toc/1814-9324 https://doaj.org/toc/1814-9332 doi:10.5194/cp-16-503-2020 1814-9324 1814-9332 https://doaj.org/article/418ff0953ced400f83918d602b4354f6 |
op_doi |
https://doi.org/10.5194/cp-16-503-2020 |
container_title |
Climate of the Past |
container_volume |
16 |
container_issue |
2 |
container_start_page |
503 |
op_container_end_page |
522 |
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1766270129611472896 |