A rapidly converging initialisation method to simulate the present-day Greenland ice sheet using the GRISLI ice sheet model (version 1.3)
Providing reliable projections of the ice sheet contribution to future sea-level rise has become one of the main challenges of the ice sheet modelling community. To increase confidence in future projections, a good knowledge of the present-day state of ice flow dynamics, which is critically dependen...
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ftdoajarticles:oai:doaj.org/article:fdad1382bf0143e6b39f902b79d010d1 2023-05-15T16:28:59+02:00 A rapidly converging initialisation method to simulate the present-day Greenland ice sheet using the GRISLI ice sheet model (version 1.3) S. Le clec'h A. Quiquet S. Charbit C. Dumas M. Kageyama C. Ritz 2019-06-01T00:00:00Z https://doi.org/10.5194/gmd-12-2481-2019 https://doaj.org/article/fdad1382bf0143e6b39f902b79d010d1 EN eng Copernicus Publications https://www.geosci-model-dev.net/12/2481/2019/gmd-12-2481-2019.pdf https://doaj.org/toc/1991-959X https://doaj.org/toc/1991-9603 doi:10.5194/gmd-12-2481-2019 1991-959X 1991-9603 https://doaj.org/article/fdad1382bf0143e6b39f902b79d010d1 Geoscientific Model Development, Vol 12, Pp 2481-2499 (2019) Geology QE1-996.5 article 2019 ftdoajarticles https://doi.org/10.5194/gmd-12-2481-2019 2022-12-31T06:44:04Z Providing reliable projections of the ice sheet contribution to future sea-level rise has become one of the main challenges of the ice sheet modelling community. To increase confidence in future projections, a good knowledge of the present-day state of ice flow dynamics, which is critically dependent on basal conditions, is strongly needed. The main difficulty is tied to the scarcity of observations at the ice–bed interface at the scale of the whole ice sheet, resulting in poorly constrained parameterisations in ice sheet models. To circumvent this drawback, inverse modelling approaches can be developed to infer initial conditions for ice sheet models that best reproduce available data. Most often such approaches allow for a good representation of the mean present-day state of the ice sheet but are accompanied with unphysical trends. Here, we present an initialisation method for the Greenland ice sheet using the thermo-mechanical hybrid GRISLI (GRenoble Ice Shelf and Land Ice) ice sheet model. Our approach is based on the adjustment of the basal drag coefficient that relates the sliding velocities at the ice–bed interface to basal shear stress in unfrozen bed areas. This method relies on an iterative process in which the basal drag is periodically adjusted in such a way that the simulated ice thickness matches the observed one. The quality of the method is assessed by computing the root mean square errors in ice thickness changes. Because the method is based on an adjustment of the sliding velocities only, the results are discussed in terms of varying ice flow enhancement factors that control the deformation rates. We show that this factor has a strong impact on the minimisation of ice thickness errors and has to be chosen as a function of the internal thermal state of the ice sheet (e.g. a low enhancement factor for a warm ice sheet). While the method performance slightly increases with the duration of the minimisation procedure, an ice thickness root mean square error (RMSE) of 50.3 m is obtained in only 1320 ... Article in Journal/Newspaper Greenland Ice Sheet Ice Shelf Directory of Open Access Journals: DOAJ Articles Greenland Geoscientific Model Development 12 6 2481 2499 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Geology QE1-996.5 |
spellingShingle |
Geology QE1-996.5 S. Le clec'h A. Quiquet S. Charbit C. Dumas M. Kageyama C. Ritz A rapidly converging initialisation method to simulate the present-day Greenland ice sheet using the GRISLI ice sheet model (version 1.3) |
topic_facet |
Geology QE1-996.5 |
description |
Providing reliable projections of the ice sheet contribution to future sea-level rise has become one of the main challenges of the ice sheet modelling community. To increase confidence in future projections, a good knowledge of the present-day state of ice flow dynamics, which is critically dependent on basal conditions, is strongly needed. The main difficulty is tied to the scarcity of observations at the ice–bed interface at the scale of the whole ice sheet, resulting in poorly constrained parameterisations in ice sheet models. To circumvent this drawback, inverse modelling approaches can be developed to infer initial conditions for ice sheet models that best reproduce available data. Most often such approaches allow for a good representation of the mean present-day state of the ice sheet but are accompanied with unphysical trends. Here, we present an initialisation method for the Greenland ice sheet using the thermo-mechanical hybrid GRISLI (GRenoble Ice Shelf and Land Ice) ice sheet model. Our approach is based on the adjustment of the basal drag coefficient that relates the sliding velocities at the ice–bed interface to basal shear stress in unfrozen bed areas. This method relies on an iterative process in which the basal drag is periodically adjusted in such a way that the simulated ice thickness matches the observed one. The quality of the method is assessed by computing the root mean square errors in ice thickness changes. Because the method is based on an adjustment of the sliding velocities only, the results are discussed in terms of varying ice flow enhancement factors that control the deformation rates. We show that this factor has a strong impact on the minimisation of ice thickness errors and has to be chosen as a function of the internal thermal state of the ice sheet (e.g. a low enhancement factor for a warm ice sheet). While the method performance slightly increases with the duration of the minimisation procedure, an ice thickness root mean square error (RMSE) of 50.3 m is obtained in only 1320 ... |
format |
Article in Journal/Newspaper |
author |
S. Le clec'h A. Quiquet S. Charbit C. Dumas M. Kageyama C. Ritz |
author_facet |
S. Le clec'h A. Quiquet S. Charbit C. Dumas M. Kageyama C. Ritz |
author_sort |
S. Le clec'h |
title |
A rapidly converging initialisation method to simulate the present-day Greenland ice sheet using the GRISLI ice sheet model (version 1.3) |
title_short |
A rapidly converging initialisation method to simulate the present-day Greenland ice sheet using the GRISLI ice sheet model (version 1.3) |
title_full |
A rapidly converging initialisation method to simulate the present-day Greenland ice sheet using the GRISLI ice sheet model (version 1.3) |
title_fullStr |
A rapidly converging initialisation method to simulate the present-day Greenland ice sheet using the GRISLI ice sheet model (version 1.3) |
title_full_unstemmed |
A rapidly converging initialisation method to simulate the present-day Greenland ice sheet using the GRISLI ice sheet model (version 1.3) |
title_sort |
rapidly converging initialisation method to simulate the present-day greenland ice sheet using the grisli ice sheet model (version 1.3) |
publisher |
Copernicus Publications |
publishDate |
2019 |
url |
https://doi.org/10.5194/gmd-12-2481-2019 https://doaj.org/article/fdad1382bf0143e6b39f902b79d010d1 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Ice Sheet Ice Shelf |
genre_facet |
Greenland Ice Sheet Ice Shelf |
op_source |
Geoscientific Model Development, Vol 12, Pp 2481-2499 (2019) |
op_relation |
https://www.geosci-model-dev.net/12/2481/2019/gmd-12-2481-2019.pdf https://doaj.org/toc/1991-959X https://doaj.org/toc/1991-9603 doi:10.5194/gmd-12-2481-2019 1991-959X 1991-9603 https://doaj.org/article/fdad1382bf0143e6b39f902b79d010d1 |
op_doi |
https://doi.org/10.5194/gmd-12-2481-2019 |
container_title |
Geoscientific Model Development |
container_volume |
12 |
container_issue |
6 |
container_start_page |
2481 |
op_container_end_page |
2499 |
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