A Variational Method for Sea Ice Ridging in Earth System Models
The article of record as published may be found at https://doi.org/10.1029/2018MS001395 We have derived an analytic form of the thickness redistribution function, Ψ, and compressive strength of sea ice using variational principles. By using the technique of coarse‐graining vertical sea ice deformati...
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ftnavalpschool:oai:calhoun.nps.edu:10945/62692 2024-06-09T07:49:26+00:00 A Variational Method for Sea Ice Ridging in Earth System Models Roberts, A.F. Hunke, E.C. Kamal, S.M. Lipscomb, WH Horvat, C. Maslowski, W. Naval Postgraduate School (U.S.) Oceanography 2019-03 35 p. application/pdf https://hdl.handle.net/10945/62692 unknown Roberts, Andrew F., et al. "A Variational Method for Sea Ice Ridging in Earth System Models." Journal of Advances in Modeling Earth Systems 11.3 (2019): 771-805. https://hdl.handle.net/10945/62692 This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States. Article 2019 ftnavalpschool 2024-05-15T00:33:09Z The article of record as published may be found at https://doi.org/10.1029/2018MS001395 We have derived an analytic form of the thickness redistribution function, Ψ, and compressive strength of sea ice using variational principles. By using the technique of coarse‐graining vertical sea ice deformation, or ridging, in the momentum equation of the pack, we isolate frictional energy loss from potential energy gain in the collision of floes. The method accounts for macroporosity of ridge rubble, ϕR, and by including this in the state space of the pack, we expand the sea ice thickness distribution, g(h), to a bivariate distribution, g(h,ϕR). The effect of macroporosity is for the first time included in the large‐scale mass conservation and momentum equations of frozen oceans. We make assumptions that have simplified the problem, such as treating sea ice as a granular material in ridges, and assuming that bending moments associated with ridging are perturbations around an isostatic state. Regardless of these simplifications, the coarse‐grained ridge model is highly predictive of macroporosity and ridge shape. By ensuring that vertical sea ice deformation observes a variational principle both at the scale of individual ridges and over the pack as a whole, we can predict distributions of ridge shapes using equations that can be solved in Earth system models. Our method also offers the possibility of more accurate derivations of sea ice thickness from ice freeboard measured by space‐borne altimeters over polar oceans. Article in Journal/Newspaper Sea ice Naval Postgraduate School: Calhoun |
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Naval Postgraduate School: Calhoun |
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The article of record as published may be found at https://doi.org/10.1029/2018MS001395 We have derived an analytic form of the thickness redistribution function, Ψ, and compressive strength of sea ice using variational principles. By using the technique of coarse‐graining vertical sea ice deformation, or ridging, in the momentum equation of the pack, we isolate frictional energy loss from potential energy gain in the collision of floes. The method accounts for macroporosity of ridge rubble, ϕR, and by including this in the state space of the pack, we expand the sea ice thickness distribution, g(h), to a bivariate distribution, g(h,ϕR). The effect of macroporosity is for the first time included in the large‐scale mass conservation and momentum equations of frozen oceans. We make assumptions that have simplified the problem, such as treating sea ice as a granular material in ridges, and assuming that bending moments associated with ridging are perturbations around an isostatic state. Regardless of these simplifications, the coarse‐grained ridge model is highly predictive of macroporosity and ridge shape. By ensuring that vertical sea ice deformation observes a variational principle both at the scale of individual ridges and over the pack as a whole, we can predict distributions of ridge shapes using equations that can be solved in Earth system models. Our method also offers the possibility of more accurate derivations of sea ice thickness from ice freeboard measured by space‐borne altimeters over polar oceans. |
author2 |
Naval Postgraduate School (U.S.) Oceanography |
format |
Article in Journal/Newspaper |
author |
Roberts, A.F. Hunke, E.C. Kamal, S.M. Lipscomb, WH Horvat, C. Maslowski, W. |
spellingShingle |
Roberts, A.F. Hunke, E.C. Kamal, S.M. Lipscomb, WH Horvat, C. Maslowski, W. A Variational Method for Sea Ice Ridging in Earth System Models |
author_facet |
Roberts, A.F. Hunke, E.C. Kamal, S.M. Lipscomb, WH Horvat, C. Maslowski, W. |
author_sort |
Roberts, A.F. |
title |
A Variational Method for Sea Ice Ridging in Earth System Models |
title_short |
A Variational Method for Sea Ice Ridging in Earth System Models |
title_full |
A Variational Method for Sea Ice Ridging in Earth System Models |
title_fullStr |
A Variational Method for Sea Ice Ridging in Earth System Models |
title_full_unstemmed |
A Variational Method for Sea Ice Ridging in Earth System Models |
title_sort |
variational method for sea ice ridging in earth system models |
publishDate |
2019 |
url |
https://hdl.handle.net/10945/62692 |
genre |
Sea ice |
genre_facet |
Sea ice |
op_relation |
Roberts, Andrew F., et al. "A Variational Method for Sea Ice Ridging in Earth System Models." Journal of Advances in Modeling Earth Systems 11.3 (2019): 771-805. https://hdl.handle.net/10945/62692 |
op_rights |
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States. |
_version_ |
1801381997503840256 |