A new approach to inferring basal drag and ice rheology in ice streams, with applications to West Antarctic Ice Streams
<jats:title>Abstract</jats:title><jats:p>Drag at the bed and along the lateral margins are the primary forces resisting flow in outlet glaciers. Simultaneously inferring these parameters is challenging since basal drag and ice viscosity are coupled in the momentum balance, which go...
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ftmit:oai:dspace.mit.edu:1721.1/133819 2023-06-11T04:06:12+02:00 A new approach to inferring basal drag and ice rheology in ice streams, with applications to West Antarctic Ice Streams Ranganathan, Meghana Minchew, Brent Meyer, Colin R Gudmundsson, G Hilmar 2021-09-17T16:03:38Z application/pdf https://hdl.handle.net/1721.1/133819 en eng Cambridge University Press (CUP) 10.1017/JOG.2020.95 Journal of Glaciology https://hdl.handle.net/1721.1/133819 Creative Commons Attribution 4.0 International license https://creativecommons.org/licenses/by/4.0/ Cambridge University Press Article http://purl.org/eprint/type/JournalArticle 2021 ftmit 2023-05-29T08:22:36Z <jats:title>Abstract</jats:title><jats:p>Drag at the bed and along the lateral margins are the primary forces resisting flow in outlet glaciers. Simultaneously inferring these parameters is challenging since basal drag and ice viscosity are coupled in the momentum balance, which governs ice flow. We test the ability of adjoint-based inverse methods to infer the slipperiness coefficient in a power-law sliding law and the flow-rate parameter in the constitutive relation for ice using a regularization scheme that includes coefficients weighted by surface strain rates. Using synthetic data with spatial variations in basal drag and ice rheology comparable to those in West Antarctic Ice Streams, we show that this approach allows for more accurate inferences. We apply this method to Bindschadler and MacAyeal Ice Streams in West Antarctica. Our results show relatively soft ice in the shear margins and spatially varying basal drag, with an increase in drag with distance upstream of the grounding line punctuated by localized areas of relatively high drag. We interpret soft ice to reflect a combination of heating through viscous dissipation and changes in the crystalline structure. These results suggest that adjoint-based inverse methods can provide inferences of basal drag and ice rheology when regularization is informed by strain rates.</jats:p> Article in Journal/Newspaper Antarc* Antarctic Antarctica Journal of Glaciology West Antarctica DSpace@MIT (Massachusetts Institute of Technology) Antarctic West Antarctica |
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DSpace@MIT (Massachusetts Institute of Technology) |
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language |
English |
description |
<jats:title>Abstract</jats:title><jats:p>Drag at the bed and along the lateral margins are the primary forces resisting flow in outlet glaciers. Simultaneously inferring these parameters is challenging since basal drag and ice viscosity are coupled in the momentum balance, which governs ice flow. We test the ability of adjoint-based inverse methods to infer the slipperiness coefficient in a power-law sliding law and the flow-rate parameter in the constitutive relation for ice using a regularization scheme that includes coefficients weighted by surface strain rates. Using synthetic data with spatial variations in basal drag and ice rheology comparable to those in West Antarctic Ice Streams, we show that this approach allows for more accurate inferences. We apply this method to Bindschadler and MacAyeal Ice Streams in West Antarctica. Our results show relatively soft ice in the shear margins and spatially varying basal drag, with an increase in drag with distance upstream of the grounding line punctuated by localized areas of relatively high drag. We interpret soft ice to reflect a combination of heating through viscous dissipation and changes in the crystalline structure. These results suggest that adjoint-based inverse methods can provide inferences of basal drag and ice rheology when regularization is informed by strain rates.</jats:p> |
format |
Article in Journal/Newspaper |
author |
Ranganathan, Meghana Minchew, Brent Meyer, Colin R Gudmundsson, G Hilmar |
spellingShingle |
Ranganathan, Meghana Minchew, Brent Meyer, Colin R Gudmundsson, G Hilmar A new approach to inferring basal drag and ice rheology in ice streams, with applications to West Antarctic Ice Streams |
author_facet |
Ranganathan, Meghana Minchew, Brent Meyer, Colin R Gudmundsson, G Hilmar |
author_sort |
Ranganathan, Meghana |
title |
A new approach to inferring basal drag and ice rheology in ice streams, with applications to West Antarctic Ice Streams |
title_short |
A new approach to inferring basal drag and ice rheology in ice streams, with applications to West Antarctic Ice Streams |
title_full |
A new approach to inferring basal drag and ice rheology in ice streams, with applications to West Antarctic Ice Streams |
title_fullStr |
A new approach to inferring basal drag and ice rheology in ice streams, with applications to West Antarctic Ice Streams |
title_full_unstemmed |
A new approach to inferring basal drag and ice rheology in ice streams, with applications to West Antarctic Ice Streams |
title_sort |
new approach to inferring basal drag and ice rheology in ice streams, with applications to west antarctic ice streams |
publisher |
Cambridge University Press (CUP) |
publishDate |
2021 |
url |
https://hdl.handle.net/1721.1/133819 |
geographic |
Antarctic West Antarctica |
geographic_facet |
Antarctic West Antarctica |
genre |
Antarc* Antarctic Antarctica Journal of Glaciology West Antarctica |
genre_facet |
Antarc* Antarctic Antarctica Journal of Glaciology West Antarctica |
op_source |
Cambridge University Press |
op_relation |
10.1017/JOG.2020.95 Journal of Glaciology https://hdl.handle.net/1721.1/133819 |
op_rights |
Creative Commons Attribution 4.0 International license https://creativecommons.org/licenses/by/4.0/ |
_version_ |
1768378010773225472 |