A quasi-analytical ice-sheet model for climate studies

International audience A simple quasi-analytical model is developed to study the response of ice-sheets to climate change. The model is axisymmetrical and rests on a bed with a constant slope. The mechanics are highly parameterised. The climatic conditions are represented by the altitude of the runo...

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Main Author: Oerlemans, J.
Other Authors: Institute for Marine and Atmospheric Research Utrecht (IMAU), Universiteit Utrecht / Utrecht University Utrecht
Format: Article in Journal/Newspaper
Language:English
Published: HAL CCSD 2003
Subjects:
Online Access:https://hal.science/hal-00302241
https://hal.science/hal-00302241/document
https://hal.science/hal-00302241/file/npg-10-441-2003.pdf
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spelling ftinsu:oai:HAL:hal-00302241v1 2023-12-03T10:22:37+01:00 A quasi-analytical ice-sheet model for climate studies Oerlemans, J. Institute for Marine and Atmospheric Research Utrecht (IMAU) Universiteit Utrecht / Utrecht University Utrecht 2003 https://hal.science/hal-00302241 https://hal.science/hal-00302241/document https://hal.science/hal-00302241/file/npg-10-441-2003.pdf en eng HAL CCSD European Geosciences Union (EGU) hal-00302241 https://hal.science/hal-00302241 https://hal.science/hal-00302241/document https://hal.science/hal-00302241/file/npg-10-441-2003.pdf info:eu-repo/semantics/OpenAccess ISSN: 1023-5809 EISSN: 1607-7946 Nonlinear Processes in Geophysics https://hal.science/hal-00302241 Nonlinear Processes in Geophysics, 2003, 10 (4/5), pp.441-452 [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO] [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph] [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/article Journal articles 2003 ftinsu 2023-11-08T17:28:24Z International audience A simple quasi-analytical model is developed to study the response of ice-sheets to climate change. The model is axisymmetrical and rests on a bed with a constant slope. The mechanics are highly parameterised. The climatic conditions are represented by the altitude of the runoff line. Above the runoff line the accumulation rate is constant (but may depend on, for instance, the ice-sheet size), below the runoff line the balance gradient is constant. The ice-sheet may extend into the sea and can respond to changes in sea level. At the grounding line the ice velocity is assumed to be proportional to the water depth. For this set-up an explicit expression for the total mass budget of the ice-sheet is derived. To illustrate the properties and possibilities of the model, equilibrium states are analysed and the response to periodic forcing is studied as well. The coupling of mass balance and surface elevation of the ice-sheet leads to nonlinear behaviour and branching of the equilibrium solutions. The qualitative behaviour of the system is that of the cusp catastrophe. Nonlinear effects are more pronounced when the slope of the bed is smaller. A case is discussed in which two ice-sheets are coupled by making the altitude of the runoff line dependent on the total area of the two ice-sheets. On two continents, having a slightly different glaciation threshold, periodic forcing of the altitude of the runoff line is imposed. It is shown that in such a situation variations on a long time scale (two to three times the period of the forcing) are introduced. Finally the model is forced by the GISP d 18 O record for the last 120 000 years. For an appropriate choice of parameters the model simulates well the waxing and waning of the Laurentide, Fennoscandian and Barentsz ice-sheets. Article in Journal/Newspaper Fennoscandian Ice Sheet Institut national des sciences de l'Univers: HAL-INSU
institution Open Polar
collection Institut national des sciences de l'Univers: HAL-INSU
op_collection_id ftinsu
language English
topic [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph]
[SDU.STU]Sciences of the Universe [physics]/Earth Sciences
spellingShingle [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph]
[SDU.STU]Sciences of the Universe [physics]/Earth Sciences
Oerlemans, J.
A quasi-analytical ice-sheet model for climate studies
topic_facet [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph]
[SDU.STU]Sciences of the Universe [physics]/Earth Sciences
description International audience A simple quasi-analytical model is developed to study the response of ice-sheets to climate change. The model is axisymmetrical and rests on a bed with a constant slope. The mechanics are highly parameterised. The climatic conditions are represented by the altitude of the runoff line. Above the runoff line the accumulation rate is constant (but may depend on, for instance, the ice-sheet size), below the runoff line the balance gradient is constant. The ice-sheet may extend into the sea and can respond to changes in sea level. At the grounding line the ice velocity is assumed to be proportional to the water depth. For this set-up an explicit expression for the total mass budget of the ice-sheet is derived. To illustrate the properties and possibilities of the model, equilibrium states are analysed and the response to periodic forcing is studied as well. The coupling of mass balance and surface elevation of the ice-sheet leads to nonlinear behaviour and branching of the equilibrium solutions. The qualitative behaviour of the system is that of the cusp catastrophe. Nonlinear effects are more pronounced when the slope of the bed is smaller. A case is discussed in which two ice-sheets are coupled by making the altitude of the runoff line dependent on the total area of the two ice-sheets. On two continents, having a slightly different glaciation threshold, periodic forcing of the altitude of the runoff line is imposed. It is shown that in such a situation variations on a long time scale (two to three times the period of the forcing) are introduced. Finally the model is forced by the GISP d 18 O record for the last 120 000 years. For an appropriate choice of parameters the model simulates well the waxing and waning of the Laurentide, Fennoscandian and Barentsz ice-sheets.
author2 Institute for Marine and Atmospheric Research Utrecht (IMAU)
Universiteit Utrecht / Utrecht University Utrecht
format Article in Journal/Newspaper
author Oerlemans, J.
author_facet Oerlemans, J.
author_sort Oerlemans, J.
title A quasi-analytical ice-sheet model for climate studies
title_short A quasi-analytical ice-sheet model for climate studies
title_full A quasi-analytical ice-sheet model for climate studies
title_fullStr A quasi-analytical ice-sheet model for climate studies
title_full_unstemmed A quasi-analytical ice-sheet model for climate studies
title_sort quasi-analytical ice-sheet model for climate studies
publisher HAL CCSD
publishDate 2003
url https://hal.science/hal-00302241
https://hal.science/hal-00302241/document
https://hal.science/hal-00302241/file/npg-10-441-2003.pdf
genre Fennoscandian
Ice Sheet
genre_facet Fennoscandian
Ice Sheet
op_source ISSN: 1023-5809
EISSN: 1607-7946
Nonlinear Processes in Geophysics
https://hal.science/hal-00302241
Nonlinear Processes in Geophysics, 2003, 10 (4/5), pp.441-452
op_relation hal-00302241
https://hal.science/hal-00302241
https://hal.science/hal-00302241/document
https://hal.science/hal-00302241/file/npg-10-441-2003.pdf
op_rights info:eu-repo/semantics/OpenAccess
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