Turbulence observations beneath Larsen C Ice Shelf, Antarctica
Increased ocean‐driven basal melting beneath Antarctic ice shelves causes grounded ice to flow into the ocean at an accelerated rate, with consequences for global sea level. The turbulent transfer of heat through the ice shelf‐ocean boundary layer is critical in setting the basal melt rate, yet the...
Published in: | Journal of Geophysical Research: Oceans |
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American Geophysical Union
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ftnerc:oai:nora.nerc.ac.uk:523077 2023-05-15T13:41:43+02:00 Turbulence observations beneath Larsen C Ice Shelf, Antarctica Davis, Peter E.D. Nicholls, Keith W. 2019-08 text http://nora.nerc.ac.uk/id/eprint/523077/ https://nora.nerc.ac.uk/id/eprint/523077/1/Davis_et_al-2019-Journal_of_Geophysical_Research__Oceans.pdf https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019JC015164 en eng American Geophysical Union https://nora.nerc.ac.uk/id/eprint/523077/1/Davis_et_al-2019-Journal_of_Geophysical_Research__Oceans.pdf Davis, Peter E.D. orcid:0000-0002-6471-6310 Nicholls, Keith W. orcid:0000-0002-2188-4509 . 2019 Turbulence observations beneath Larsen C Ice Shelf, Antarctica. Journal of Geophysical Research: Oceans, 124 (8). 5529-5550. https://doi.org/10.1029/2019JC015164 <https://doi.org/10.1029/2019JC015164> cc_by_4 CC-BY Publication - Article PeerReviewed 2019 ftnerc https://doi.org/10.1029/2019JC015164 2023-02-04T19:48:11Z Increased ocean‐driven basal melting beneath Antarctic ice shelves causes grounded ice to flow into the ocean at an accelerated rate, with consequences for global sea level. The turbulent transfer of heat through the ice shelf‐ocean boundary layer is critical in setting the basal melt rate, yet the processes controlling this transfer are poorly understood and inadequately represented in global climate models. This creates large uncertainties in predictions of future sea‐level rise. Using a hot‐water drilled access hole, two turbulence instrument clusters (TICs) were deployed 2.5 and 13.5 meters beneath Larsen C Ice Shelf in December 2011. Both instruments returned a year‐long record of turbulent velocity fluctuations, providing a unique opportunity to explore the turbulent processes within the ice shelf‐ocean boundary layer. Although the scaling between the turbulent kinetic energy (TKE) dissipation rate and mean flow speed varies with distance from the ice shelf base, at both TICs the TKE dissipation rate is balanced entirely by the rate of shear production. The freshwater released by basal melting plays no role in the TKE balance. When the upper TIC is within the log‐layer, we derive an under‐ice drag coefficient of 0.0022 and a roughness length of 0.44 mm, indicating that the ice base is smooth. Finally, we demonstrate that although the canonical three‐equation melt rate parameterization can accurately predict the melt rate for this example of smooth ice underlain by a cold, tidally‐forced boundary layer, the law of the wall assumption employed by the parameterization does not hold at low flow speeds. Article in Journal/Newspaper Antarc* Antarctic Antarctica Antarctica Journal Ice Shelf Ice Shelves Natural Environment Research Council: NERC Open Research Archive Antarctic Journal of Geophysical Research: Oceans 124 8 5529 5550 |
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Open Polar |
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Natural Environment Research Council: NERC Open Research Archive |
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ftnerc |
language |
English |
description |
Increased ocean‐driven basal melting beneath Antarctic ice shelves causes grounded ice to flow into the ocean at an accelerated rate, with consequences for global sea level. The turbulent transfer of heat through the ice shelf‐ocean boundary layer is critical in setting the basal melt rate, yet the processes controlling this transfer are poorly understood and inadequately represented in global climate models. This creates large uncertainties in predictions of future sea‐level rise. Using a hot‐water drilled access hole, two turbulence instrument clusters (TICs) were deployed 2.5 and 13.5 meters beneath Larsen C Ice Shelf in December 2011. Both instruments returned a year‐long record of turbulent velocity fluctuations, providing a unique opportunity to explore the turbulent processes within the ice shelf‐ocean boundary layer. Although the scaling between the turbulent kinetic energy (TKE) dissipation rate and mean flow speed varies with distance from the ice shelf base, at both TICs the TKE dissipation rate is balanced entirely by the rate of shear production. The freshwater released by basal melting plays no role in the TKE balance. When the upper TIC is within the log‐layer, we derive an under‐ice drag coefficient of 0.0022 and a roughness length of 0.44 mm, indicating that the ice base is smooth. Finally, we demonstrate that although the canonical three‐equation melt rate parameterization can accurately predict the melt rate for this example of smooth ice underlain by a cold, tidally‐forced boundary layer, the law of the wall assumption employed by the parameterization does not hold at low flow speeds. |
format |
Article in Journal/Newspaper |
author |
Davis, Peter E.D. Nicholls, Keith W. |
spellingShingle |
Davis, Peter E.D. Nicholls, Keith W. Turbulence observations beneath Larsen C Ice Shelf, Antarctica |
author_facet |
Davis, Peter E.D. Nicholls, Keith W. |
author_sort |
Davis, Peter E.D. |
title |
Turbulence observations beneath Larsen C Ice Shelf, Antarctica |
title_short |
Turbulence observations beneath Larsen C Ice Shelf, Antarctica |
title_full |
Turbulence observations beneath Larsen C Ice Shelf, Antarctica |
title_fullStr |
Turbulence observations beneath Larsen C Ice Shelf, Antarctica |
title_full_unstemmed |
Turbulence observations beneath Larsen C Ice Shelf, Antarctica |
title_sort |
turbulence observations beneath larsen c ice shelf, antarctica |
publisher |
American Geophysical Union |
publishDate |
2019 |
url |
http://nora.nerc.ac.uk/id/eprint/523077/ https://nora.nerc.ac.uk/id/eprint/523077/1/Davis_et_al-2019-Journal_of_Geophysical_Research__Oceans.pdf https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019JC015164 |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic Antarctica Antarctica Journal Ice Shelf Ice Shelves |
genre_facet |
Antarc* Antarctic Antarctica Antarctica Journal Ice Shelf Ice Shelves |
op_relation |
https://nora.nerc.ac.uk/id/eprint/523077/1/Davis_et_al-2019-Journal_of_Geophysical_Research__Oceans.pdf Davis, Peter E.D. orcid:0000-0002-6471-6310 Nicholls, Keith W. orcid:0000-0002-2188-4509 . 2019 Turbulence observations beneath Larsen C Ice Shelf, Antarctica. Journal of Geophysical Research: Oceans, 124 (8). 5529-5550. https://doi.org/10.1029/2019JC015164 <https://doi.org/10.1029/2019JC015164> |
op_rights |
cc_by_4 |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1029/2019JC015164 |
container_title |
Journal of Geophysical Research: Oceans |
container_volume |
124 |
container_issue |
8 |
container_start_page |
5529 |
op_container_end_page |
5550 |
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1766154694877511680 |