Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard
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 s...
Published in: | The Cryosphere |
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Format: | Article in Journal/Newspaper |
Language: | English |
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Uppsala universitet, Luft-, vatten- och landskapslära
2017
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Online Access: | http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-334921 https://doi.org/10.5194/tc-11-2003-2017 |
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ftuppsalauniv:oai:DiVA.org:uu-334921 2023-05-15T16:22:15+02:00 Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard Fuerst, Johannes Jakob Gillet-Chaulet, Fabien Benham, Toby J. Dowdeswell, Julian A. Grabiec, Mariusz Navarro, Francisco Pettersson, Rickard Moholdt, Geir Nuth, Christopher Sass, Björn Aas, Kjetil Fettweis, Xavier Lang, Charlotte Seehaus, Thorsten Braun, Matthias 2017 application/pdf http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-334921 https://doi.org/10.5194/tc-11-2003-2017 eng eng Uppsala universitet, Luft-, vatten- och landskapslära University of Erlangen-Nuremberg, Institute of Geography University of Grenoble Alpes, CNRS, IRD, Institut des Géosciences de l’Environnement (IGE) University of Cambridge, Scott Polar Research Institute University of Silesia in Katowice, Faculty of Earth Sciences Universidad Politécnica de Madrid, Departamento de Matemática Aplicada a las Tecnologías de la Información y las Comunicaciones, desp. A302-4, ETSI de Telecomunicación Norwegian Polar Institute, Fram Centre University of Oslo, Department of Geoscience University of Liège, Department of Geography The Cryosphere, 1994-0416, 2017, 11:5, s. 2003-2032 info:eu-repo/grantAgreement/EC/FP7/226375 http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-334921 doi:10.5194/tc-11-2003-2017 ISI:000409059700001 info:eu-repo/semantics/openAccess Geology Geologi Physical Geography Naturgeografi Article in journal info:eu-repo/semantics/article text 2017 ftuppsalauniv https://doi.org/10.5194/tc-11-2003-2017 2023-02-23T21:52:10Z 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 landterminating glaciers as well as a 2400 km(2) 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 Uppsala University: Publications (DiVA) Svalbard Vestfonna ENVELOPE(20.761,20.761,79.941,79.941) The Cryosphere 11 5 2003 2032 |
institution |
Open Polar |
collection |
Uppsala University: Publications (DiVA) |
op_collection_id |
ftuppsalauniv |
language |
English |
topic |
Geology Geologi Physical Geography Naturgeografi |
spellingShingle |
Geology Geologi Physical Geography Naturgeografi Fuerst, Johannes Jakob Gillet-Chaulet, Fabien Benham, Toby J. Dowdeswell, Julian A. Grabiec, Mariusz Navarro, Francisco Pettersson, Rickard Moholdt, Geir Nuth, Christopher Sass, Björn Aas, Kjetil Fettweis, Xavier Lang, Charlotte Seehaus, Thorsten Braun, Matthias Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard |
topic_facet |
Geology Geologi Physical Geography Naturgeografi |
description |
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 landterminating glaciers as well as a 2400 km(2) 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 |
Fuerst, Johannes Jakob Gillet-Chaulet, Fabien Benham, Toby J. Dowdeswell, Julian A. Grabiec, Mariusz Navarro, Francisco Pettersson, Rickard Moholdt, Geir Nuth, Christopher Sass, Björn Aas, Kjetil Fettweis, Xavier Lang, Charlotte Seehaus, Thorsten Braun, Matthias |
author_facet |
Fuerst, Johannes Jakob Gillet-Chaulet, Fabien Benham, Toby J. Dowdeswell, Julian A. Grabiec, Mariusz Navarro, Francisco Pettersson, Rickard Moholdt, Geir Nuth, Christopher Sass, Björn Aas, Kjetil Fettweis, Xavier Lang, Charlotte Seehaus, Thorsten Braun, Matthias |
author_sort |
Fuerst, 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 |
Uppsala universitet, Luft-, vatten- och landskapslära |
publishDate |
2017 |
url |
http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-334921 https://doi.org/10.5194/tc-11-2003-2017 |
long_lat |
ENVELOPE(20.761,20.761,79.941,79.941) |
geographic |
Svalbard Vestfonna |
geographic_facet |
Svalbard Vestfonna |
genre |
glacier Ice cap Svalbard The Cryosphere Vestfonna |
genre_facet |
glacier Ice cap Svalbard The Cryosphere Vestfonna |
op_relation |
The Cryosphere, 1994-0416, 2017, 11:5, s. 2003-2032 info:eu-repo/grantAgreement/EC/FP7/226375 http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-334921 doi:10.5194/tc-11-2003-2017 ISI:000409059700001 |
op_rights |
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_ |
1766010222159069184 |