Novel automated inversion algorithm for temperature reconstruction using gas isotopes from ice cores
Greenland past temperature history can be reconstructed by forcing the output of a firn-densification and heat-diffusion model to fit multiple gas-isotope data (δ15N or δ40Ar or δ15Nexcess) extracted from ancient air in Greenland ice cores using published accumulation-rate (Acc) datasets. We present...
Published in: | Climate of the Past |
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Copernicus Publications
2018
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00005555 2023-05-15T16:00:06+02:00 Novel automated inversion algorithm for temperature reconstruction using gas isotopes from ice cores Döring, Michael Leuenberger, Markus C. 2018-06 electronic https://doi.org/10.5194/cp-14-763-2018 https://noa.gwlb.de/receive/cop_mods_00005555 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00005512/cp-14-763-2018.pdf https://cp.copernicus.org/articles/14/763/2018/cp-14-763-2018.pdf eng eng Copernicus Publications Climate of the Past -- http://www.copernicus.org/EGU/cp/cp/published_papers.html -- http://www.bibliothek.uni-regensburg.de/ezeit/?2217985 -- 1814-9332 https://doi.org/10.5194/cp-14-763-2018 https://noa.gwlb.de/receive/cop_mods_00005555 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00005512/cp-14-763-2018.pdf https://cp.copernicus.org/articles/14/763/2018/cp-14-763-2018.pdf https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess CC-BY article Verlagsveröffentlichung article Text doc-type:article 2018 ftnonlinearchiv https://doi.org/10.5194/cp-14-763-2018 2022-02-08T22:59:29Z Greenland past temperature history can be reconstructed by forcing the output of a firn-densification and heat-diffusion model to fit multiple gas-isotope data (δ15N or δ40Ar or δ15Nexcess) extracted from ancient air in Greenland ice cores using published accumulation-rate (Acc) datasets. We present here a novel methodology to solve this inverse problem, by designing a fully automated algorithm. To demonstrate the performance of this novel approach, we begin by intentionally constructing synthetic temperature histories and associated δ15N datasets, mimicking real Holocene data that we use as “true values” (targets) to be compared to the output of the algorithm. This allows us to quantify uncertainties originating from the algorithm itself. The presented approach is completely automated and therefore minimizes the “subjective” impact of manual parameter tuning, leading to reproducible temperature estimates. In contrast to many other ice-core-based temperature reconstruction methods, the presented approach is completely independent from ice-core stable-water isotopes, providing the opportunity to validate water-isotope-based reconstructions or reconstructions where water isotopes are used together with δ15N or δ40Ar. We solve the inverse problem T(δ15N, Acc) by using a combination of a Monte Carlo based iterative approach and the analysis of remaining mismatches between modelled and target data, based on cubic-spline filtering of random numbers and the laboratory-determined temperature sensitivity for nitrogen isotopes. Additionally, the presented reconstruction approach was tested by fitting measured δ40Ar and δ15Nexcess data, which led as well to a robust agreement between modelled and measured data. The obtained final mismatches follow a symmetric standard-distribution function. For the study on synthetic data, 95 % of the mismatches compared to the synthetic target data are in an envelope between 3.0 to 6.3 permeg for δ15N and 0.23 to 0.51 K for temperature (2σ, respectively). In addition to Holocene temperature reconstructions, the fitting approach can also be used for glacial temperature reconstructions. This is shown by fitting of the North Greenland Ice Core Project (NGRIP) δ15N data for two Dansgaard–Oeschger events using the presented approach, leading to results comparable to other studies. Article in Journal/Newspaper Dansgaard-Oeschger events Greenland Greenland ice core Greenland Ice core Project Greenland ice cores ice core NGRIP North Greenland North Greenland Ice Core Project Niedersächsisches Online-Archiv NOA Greenland Climate of the Past 14 6 763 788 |
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English |
topic |
article Verlagsveröffentlichung |
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article Verlagsveröffentlichung Döring, Michael Leuenberger, Markus C. Novel automated inversion algorithm for temperature reconstruction using gas isotopes from ice cores |
topic_facet |
article Verlagsveröffentlichung |
description |
Greenland past temperature history can be reconstructed by forcing the output of a firn-densification and heat-diffusion model to fit multiple gas-isotope data (δ15N or δ40Ar or δ15Nexcess) extracted from ancient air in Greenland ice cores using published accumulation-rate (Acc) datasets. We present here a novel methodology to solve this inverse problem, by designing a fully automated algorithm. To demonstrate the performance of this novel approach, we begin by intentionally constructing synthetic temperature histories and associated δ15N datasets, mimicking real Holocene data that we use as “true values” (targets) to be compared to the output of the algorithm. This allows us to quantify uncertainties originating from the algorithm itself. The presented approach is completely automated and therefore minimizes the “subjective” impact of manual parameter tuning, leading to reproducible temperature estimates. In contrast to many other ice-core-based temperature reconstruction methods, the presented approach is completely independent from ice-core stable-water isotopes, providing the opportunity to validate water-isotope-based reconstructions or reconstructions where water isotopes are used together with δ15N or δ40Ar. We solve the inverse problem T(δ15N, Acc) by using a combination of a Monte Carlo based iterative approach and the analysis of remaining mismatches between modelled and target data, based on cubic-spline filtering of random numbers and the laboratory-determined temperature sensitivity for nitrogen isotopes. Additionally, the presented reconstruction approach was tested by fitting measured δ40Ar and δ15Nexcess data, which led as well to a robust agreement between modelled and measured data. The obtained final mismatches follow a symmetric standard-distribution function. For the study on synthetic data, 95 % of the mismatches compared to the synthetic target data are in an envelope between 3.0 to 6.3 permeg for δ15N and 0.23 to 0.51 K for temperature (2σ, respectively). In addition to Holocene temperature reconstructions, the fitting approach can also be used for glacial temperature reconstructions. This is shown by fitting of the North Greenland Ice Core Project (NGRIP) δ15N data for two Dansgaard–Oeschger events using the presented approach, leading to results comparable to other studies. |
format |
Article in Journal/Newspaper |
author |
Döring, Michael Leuenberger, Markus C. |
author_facet |
Döring, Michael Leuenberger, Markus C. |
author_sort |
Döring, Michael |
title |
Novel automated inversion algorithm for temperature reconstruction using gas isotopes from ice cores |
title_short |
Novel automated inversion algorithm for temperature reconstruction using gas isotopes from ice cores |
title_full |
Novel automated inversion algorithm for temperature reconstruction using gas isotopes from ice cores |
title_fullStr |
Novel automated inversion algorithm for temperature reconstruction using gas isotopes from ice cores |
title_full_unstemmed |
Novel automated inversion algorithm for temperature reconstruction using gas isotopes from ice cores |
title_sort |
novel automated inversion algorithm for temperature reconstruction using gas isotopes from ice cores |
publisher |
Copernicus Publications |
publishDate |
2018 |
url |
https://doi.org/10.5194/cp-14-763-2018 https://noa.gwlb.de/receive/cop_mods_00005555 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00005512/cp-14-763-2018.pdf https://cp.copernicus.org/articles/14/763/2018/cp-14-763-2018.pdf |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Dansgaard-Oeschger events Greenland Greenland ice core Greenland Ice core Project Greenland ice cores ice core NGRIP North Greenland North Greenland Ice Core Project |
genre_facet |
Dansgaard-Oeschger events Greenland Greenland ice core Greenland Ice core Project Greenland ice cores ice core NGRIP North Greenland North Greenland Ice Core Project |
op_relation |
Climate of the Past -- http://www.copernicus.org/EGU/cp/cp/published_papers.html -- http://www.bibliothek.uni-regensburg.de/ezeit/?2217985 -- 1814-9332 https://doi.org/10.5194/cp-14-763-2018 https://noa.gwlb.de/receive/cop_mods_00005555 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00005512/cp-14-763-2018.pdf https://cp.copernicus.org/articles/14/763/2018/cp-14-763-2018.pdf |
op_rights |
https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.5194/cp-14-763-2018 |
container_title |
Climate of the Past |
container_volume |
14 |
container_issue |
6 |
container_start_page |
763 |
op_container_end_page |
788 |
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1766395968720207872 |