Assessing ice sheet models against the landform record: The Likelihood of Accordant Lineations Analysis (LALA) tool
Abstract Palaeo‐ice sheets leave behind a rich database regarding their past behaviour, recorded in the landscape in the form of glacial geomorphology. The most numerous landform created by these ice sheets are subglacial lineations, which generate snapshots of the direction of ice flow at fixed (ye...
Published in: | Earth Surface Processes and Landforms |
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Online Access: | http://dx.doi.org/10.1002/esp.5658 https://onlinelibrary.wiley.com/doi/pdf/10.1002/esp.5658 |
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crwiley:10.1002/esp.5658 2024-09-15T18:12:11+00:00 Assessing ice sheet models against the landform record: The Likelihood of Accordant Lineations Analysis (LALA) tool Archer, R.E. Ely, J.C. Heaton, T.J. Butcher, F.E.G. Hughes, A.L.C. Clark, C.D. H2020 European Research Council Leverhulme Trust Natural Environment Research Council 2023 http://dx.doi.org/10.1002/esp.5658 https://onlinelibrary.wiley.com/doi/pdf/10.1002/esp.5658 en eng Wiley http://creativecommons.org/licenses/by/4.0/ Earth Surface Processes and Landforms volume 48, issue 14, page 2754-2771 ISSN 0197-9337 1096-9837 journal-article 2023 crwiley https://doi.org/10.1002/esp.5658 2024-07-04T04:29:22Z Abstract Palaeo‐ice sheets leave behind a rich database regarding their past behaviour, recorded in the landscape in the form of glacial geomorphology. The most numerous landform created by these ice sheets are subglacial lineations, which generate snapshots of the direction of ice flow at fixed (yet typically unknown) points in time. Despite their relative density within the landform record, the information provided by subglacial lineations is currently underutilised in tests of numerical ice sheet models. To some extent, this is a consequence of ongoing debate regarding lineation formation, but predominantly, it reflects the lack of rigorous model‐data comparison techniques that would enable lineation information to be properly integrated. Here, we present the Likelihood of Accordant Lineations Analysis (LALA) tool. LALA provides a statistically rigorous measure of the log‐likelihood of a supplied ice sheet simulation through comparison of simulation output with both the location and direction of observed lineations. Given an ensemble of ice sheet simulations, LALA provides a formal, and statistically underpinned, quantitative assessment of each simulation's quality‐of‐fit to mapped lineations. This enables a comparison of each simulation's relative plausibility, including identification of the most likely ice sheet simulations amongst the ensemble. This is achieved by modelling lineation formation as a marked Poisson point process and comparison of observed to modelled flow directions using the von Mises distribution. LALA is flexible—users can adapt parameters to account for differing assumptions regarding lineation formation, and for variations in the level of precision required for differing model‐data comparison experiments. We provide guidelines and rationale for assigning parameter values, including an assessment of the variability between users when mapping lineations. Finally, we demonstrate the utility of LALA through application to an ensemble of simulations of the last British‐Irish Ice Sheet. This ... Article in Journal/Newspaper Ice Sheet Wiley Online Library Earth Surface Processes and Landforms |
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Open Polar |
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Wiley Online Library |
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language |
English |
description |
Abstract Palaeo‐ice sheets leave behind a rich database regarding their past behaviour, recorded in the landscape in the form of glacial geomorphology. The most numerous landform created by these ice sheets are subglacial lineations, which generate snapshots of the direction of ice flow at fixed (yet typically unknown) points in time. Despite their relative density within the landform record, the information provided by subglacial lineations is currently underutilised in tests of numerical ice sheet models. To some extent, this is a consequence of ongoing debate regarding lineation formation, but predominantly, it reflects the lack of rigorous model‐data comparison techniques that would enable lineation information to be properly integrated. Here, we present the Likelihood of Accordant Lineations Analysis (LALA) tool. LALA provides a statistically rigorous measure of the log‐likelihood of a supplied ice sheet simulation through comparison of simulation output with both the location and direction of observed lineations. Given an ensemble of ice sheet simulations, LALA provides a formal, and statistically underpinned, quantitative assessment of each simulation's quality‐of‐fit to mapped lineations. This enables a comparison of each simulation's relative plausibility, including identification of the most likely ice sheet simulations amongst the ensemble. This is achieved by modelling lineation formation as a marked Poisson point process and comparison of observed to modelled flow directions using the von Mises distribution. LALA is flexible—users can adapt parameters to account for differing assumptions regarding lineation formation, and for variations in the level of precision required for differing model‐data comparison experiments. We provide guidelines and rationale for assigning parameter values, including an assessment of the variability between users when mapping lineations. Finally, we demonstrate the utility of LALA through application to an ensemble of simulations of the last British‐Irish Ice Sheet. This ... |
author2 |
H2020 European Research Council Leverhulme Trust Natural Environment Research Council |
format |
Article in Journal/Newspaper |
author |
Archer, R.E. Ely, J.C. Heaton, T.J. Butcher, F.E.G. Hughes, A.L.C. Clark, C.D. |
spellingShingle |
Archer, R.E. Ely, J.C. Heaton, T.J. Butcher, F.E.G. Hughes, A.L.C. Clark, C.D. Assessing ice sheet models against the landform record: The Likelihood of Accordant Lineations Analysis (LALA) tool |
author_facet |
Archer, R.E. Ely, J.C. Heaton, T.J. Butcher, F.E.G. Hughes, A.L.C. Clark, C.D. |
author_sort |
Archer, R.E. |
title |
Assessing ice sheet models against the landform record: The Likelihood of Accordant Lineations Analysis (LALA) tool |
title_short |
Assessing ice sheet models against the landform record: The Likelihood of Accordant Lineations Analysis (LALA) tool |
title_full |
Assessing ice sheet models against the landform record: The Likelihood of Accordant Lineations Analysis (LALA) tool |
title_fullStr |
Assessing ice sheet models against the landform record: The Likelihood of Accordant Lineations Analysis (LALA) tool |
title_full_unstemmed |
Assessing ice sheet models against the landform record: The Likelihood of Accordant Lineations Analysis (LALA) tool |
title_sort |
assessing ice sheet models against the landform record: the likelihood of accordant lineations analysis (lala) tool |
publisher |
Wiley |
publishDate |
2023 |
url |
http://dx.doi.org/10.1002/esp.5658 https://onlinelibrary.wiley.com/doi/pdf/10.1002/esp.5658 |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
Earth Surface Processes and Landforms volume 48, issue 14, page 2754-2771 ISSN 0197-9337 1096-9837 |
op_rights |
http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.1002/esp.5658 |
container_title |
Earth Surface Processes and Landforms |
_version_ |
1810449763349299200 |