Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard
peer reviewed The basal topography is largely unknown beneath most glaciers and ice caps, and many attempts have been made to estimate a thickness field from other more accessible information at the surface. Here, we present a two-step reconstruction approach for ice thickness that solves mass conse...
Published in: | The Cryosphere |
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Format: | Article in Journal/Newspaper |
Language: | English |
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Copernicus
2017
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Online Access: | https://orbi.uliege.be/handle/2268/213940 https://orbi.uliege.be/bitstream/2268/213940/1/tc-11-2003-2017.pdf https://doi.org/10.5194/tc-11-2003-2017 |
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ftorbi:oai:orbi.ulg.ac.be:2268/213940 2024-04-21T08:02:38+00:00 Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard Fürst, Johannes Jakob Gillet-Chaulet, Fabien Benham, Toby J. Dowdeswell, Julian A. Grabiec, Mariusz Navarro, Francisco Pettersson, R. Moholdt, G. Nuth, C. Sass, B. Aas, Kjetil Fettweis, Xavier Lang, Charlotte Seehaus, T. Braun, M. 2017-09-01 https://orbi.uliege.be/handle/2268/213940 https://orbi.uliege.be/bitstream/2268/213940/1/tc-11-2003-2017.pdf https://doi.org/10.5194/tc-11-2003-2017 en eng Copernicus https://www.the-cryosphere.net/11/2003/2017/ urn:issn:1994-0416 urn:issn:1994-0424 https://orbi.uliege.be/handle/2268/213940 info:hdl:2268/213940 https://orbi.uliege.be/bitstream/2268/213940/1/tc-11-2003-2017.pdf doi:10.5194/tc-11-2003-2017 scopus-id:2-s2.0-85028693606 open access http://purl.org/coar/access_right/c_abf2 info:eu-repo/semantics/openAccess The Cryosphere (2017-09-01) Physical chemical mathematical & earth Sciences Earth sciences & physical geography Physique chimie mathématiques & sciences de la terre Sciences de la terre & géographie physique journal article http://purl.org/coar/resource_type/c_6501 info:eu-repo/semantics/article peer reviewed 2017 ftorbi https://doi.org/10.5194/tc-11-2003-2017 2024-03-27T14:58:15Z peer reviewed The basal topography is largely unknown beneath most glaciers and ice caps, and many attempts have been made to estimate a thickness field from other more accessible information at the surface. Here, we present a two-step reconstruction approach for ice thickness that solves mass conservation over single or several connected drainage basins. The approach is applied to a variety of test geometries with abundant thickness measurements including marine- and land-terminating glaciers as well as a 2400 km2 ice cap on Svalbard. The input requirements are kept to a minimum for the first step. In this step, a geometrically controlled, non-local flux solution is converted into thickness values relying on the shallow ice approximation (SIA). In a second step, the thickness field is updated along fast-flowing glacier trunks on the basis of velocity observations. Both steps account for available thickness measurements. Each thickness field is presented together with an error-estimate map based on a formal propagation of input uncertainties. These error estimates point out that the thickness field is least constrained near ice divides or in other stagnant areas. Withholding a share of the thickness measurements, error estimates tend to overestimate mismatch values in a median sense. We also have to accept an aggregate uncertainty of at least 25 % in the reconstructed thickness field for glaciers with very sparse or no observations. For Vestfonna ice cap (VIC), a previous ice volume estimate based on the same measurement record as used here has to be corrected upward by 22 %. We also find that a 13 % area fraction of the ice cap is in fact grounded below sea level. The former 5 % estimate from a direct measurement interpolation exceeds an aggregate maximum range of 6–23 % as inferred from the error estimates here. Article in Journal/Newspaper glacier Ice cap Svalbard The Cryosphere Vestfonna University of Liège: ORBi (Open Repository and Bibliography) The Cryosphere 11 5 2003 2032 |
institution |
Open Polar |
collection |
University of Liège: ORBi (Open Repository and Bibliography) |
op_collection_id |
ftorbi |
language |
English |
topic |
Physical chemical mathematical & earth Sciences Earth sciences & physical geography Physique chimie mathématiques & sciences de la terre Sciences de la terre & géographie physique |
spellingShingle |
Physical chemical mathematical & earth Sciences Earth sciences & physical geography Physique chimie mathématiques & sciences de la terre Sciences de la terre & géographie physique Fürst, Johannes Jakob Gillet-Chaulet, Fabien Benham, Toby J. Dowdeswell, Julian A. Grabiec, Mariusz Navarro, Francisco Pettersson, R. Moholdt, G. Nuth, C. Sass, B. Aas, Kjetil Fettweis, Xavier Lang, Charlotte Seehaus, T. Braun, M. Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard |
topic_facet |
Physical chemical mathematical & earth Sciences Earth sciences & physical geography Physique chimie mathématiques & sciences de la terre Sciences de la terre & géographie physique |
description |
peer reviewed The basal topography is largely unknown beneath most glaciers and ice caps, and many attempts have been made to estimate a thickness field from other more accessible information at the surface. Here, we present a two-step reconstruction approach for ice thickness that solves mass conservation over single or several connected drainage basins. The approach is applied to a variety of test geometries with abundant thickness measurements including marine- and land-terminating glaciers as well as a 2400 km2 ice cap on Svalbard. The input requirements are kept to a minimum for the first step. In this step, a geometrically controlled, non-local flux solution is converted into thickness values relying on the shallow ice approximation (SIA). In a second step, the thickness field is updated along fast-flowing glacier trunks on the basis of velocity observations. Both steps account for available thickness measurements. Each thickness field is presented together with an error-estimate map based on a formal propagation of input uncertainties. These error estimates point out that the thickness field is least constrained near ice divides or in other stagnant areas. Withholding a share of the thickness measurements, error estimates tend to overestimate mismatch values in a median sense. We also have to accept an aggregate uncertainty of at least 25 % in the reconstructed thickness field for glaciers with very sparse or no observations. For Vestfonna ice cap (VIC), a previous ice volume estimate based on the same measurement record as used here has to be corrected upward by 22 %. We also find that a 13 % area fraction of the ice cap is in fact grounded below sea level. The former 5 % estimate from a direct measurement interpolation exceeds an aggregate maximum range of 6–23 % as inferred from the error estimates here. |
format |
Article in Journal/Newspaper |
author |
Fürst, Johannes Jakob Gillet-Chaulet, Fabien Benham, Toby J. Dowdeswell, Julian A. Grabiec, Mariusz Navarro, Francisco Pettersson, R. Moholdt, G. Nuth, C. Sass, B. Aas, Kjetil Fettweis, Xavier Lang, Charlotte Seehaus, T. Braun, M. |
author_facet |
Fürst, Johannes Jakob Gillet-Chaulet, Fabien Benham, Toby J. Dowdeswell, Julian A. Grabiec, Mariusz Navarro, Francisco Pettersson, R. Moholdt, G. Nuth, C. Sass, B. Aas, Kjetil Fettweis, Xavier Lang, Charlotte Seehaus, T. Braun, M. |
author_sort |
Fürst, Johannes Jakob |
title |
Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard |
title_short |
Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard |
title_full |
Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard |
title_fullStr |
Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard |
title_full_unstemmed |
Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard |
title_sort |
application of a two-step approach for mapping ice thickness to various glacier types on svalbard |
publisher |
Copernicus |
publishDate |
2017 |
url |
https://orbi.uliege.be/handle/2268/213940 https://orbi.uliege.be/bitstream/2268/213940/1/tc-11-2003-2017.pdf https://doi.org/10.5194/tc-11-2003-2017 |
genre |
glacier Ice cap Svalbard The Cryosphere Vestfonna |
genre_facet |
glacier Ice cap Svalbard The Cryosphere Vestfonna |
op_source |
The Cryosphere (2017-09-01) |
op_relation |
https://www.the-cryosphere.net/11/2003/2017/ urn:issn:1994-0416 urn:issn:1994-0424 https://orbi.uliege.be/handle/2268/213940 info:hdl:2268/213940 https://orbi.uliege.be/bitstream/2268/213940/1/tc-11-2003-2017.pdf doi:10.5194/tc-11-2003-2017 scopus-id:2-s2.0-85028693606 |
op_rights |
open access http://purl.org/coar/access_right/c_abf2 info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/tc-11-2003-2017 |
container_title |
The Cryosphere |
container_volume |
11 |
container_issue |
5 |
container_start_page |
2003 |
op_container_end_page |
2032 |
_version_ |
1796942778471546880 |