Regimes and Transitions in the Basal Melting of Antarctic Ice Shelves
Abstract The Antarctic Ice Sheet is losing mass as a result of increased ocean-driven melting of its fringing ice shelves. Efforts to represent the effects of basal melting in sea level projections are undermined by poor understanding of the turbulent ice shelf–ocean boundary layer (ISOBL), a meters...
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AMER METEOROLOGICAL SOC
2022
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ftumelbourne:oai:jupiter.its.unimelb.edu.au:11343/333537 2024-06-02T07:58:42+00:00 Regimes and Transitions in the Basal Melting of Antarctic Ice Shelves Rosevear, MG Gayen, B Galton-Fenzi, BK 2022-10 http://hdl.handle.net/11343/333537 English eng AMER METEOROLOGICAL SOC issn:0022-3670 doi:10.1175/JPO-D-21-0317.1 Rosevear, M. G., Gayen, B. & Galton-Fenzi, B. K. (2022). Regimes and Transitions in the Basal Melting of Antarctic Ice Shelves. JOURNAL OF PHYSICAL OCEANOGRAPHY, 52 (10), pp.2589-2608. https://doi.org/10.1175/JPO-D-21-0317.1. 1520-0485 http://hdl.handle.net/11343/333537 Journal Article 2022 ftumelbourne https://doi.org/10.1175/JPO-D-21-0317.1 2024-05-06T13:11:17Z Abstract The Antarctic Ice Sheet is losing mass as a result of increased ocean-driven melting of its fringing ice shelves. Efforts to represent the effects of basal melting in sea level projections are undermined by poor understanding of the turbulent ice shelf–ocean boundary layer (ISOBL), a meters-thick layer of ocean that regulates heat and salt transfer between the ocean and ice. To address this shortcoming, we perform large-eddy simulations of the ISOBL formed by a steady, geostrophic flow beneath horizontal ice. We investigate melting and ISOBL structure and properties over a range of free-stream velocities and ocean temperatures. We find that the melting response to changes in thermal and current forcing is highly nonlinear due to the effects of meltwater on ISOBL turbulence. Three distinct ISOBL regimes emerge depending on the relative strength of current shear and buoyancy forcing: “well-mixed,” “stratified,” or “diffusive-convective.” We present expressions for mixing-layer depth for each regime and show that the transitions between regimes can be predicted with simple nondimensional parameters. We use these results to develop a novel regime diagram for the ISOBL which provides insight into the varied melting responses expected around Antarctica and highlights the need to include stratified and diffusive-convective dynamics in future basal melting parameterizations. We emphasize that melting in the diffusive-convective regime is time dependent and is therefore inherently difficult to parameterize. Significance Statement The purpose of this study is to investigate the processes that control ocean-driven melting of Antarctic ice shelves (100–1000-m-thick floating extensions of the Antarctic ice sheet). Currently, these processes are poorly understood due to the difficulty of accessing the ocean beneath ice shelves. Using an ocean model, we determine the melting response to different ocean conditions, including feedbacks whereby cold, fresh meltwater can enhance or suppress turbulent eddies beneath the ... Article in Journal/Newspaper Antarc* Antarctic Antarctica Ice Sheet Ice Shelf Ice Shelves The University of Melbourne: Digital Repository Antarctic The Antarctic Journal of Physical Oceanography 52 10 2589 2608 |
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Open Polar |
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The University of Melbourne: Digital Repository |
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ftumelbourne |
language |
English |
description |
Abstract The Antarctic Ice Sheet is losing mass as a result of increased ocean-driven melting of its fringing ice shelves. Efforts to represent the effects of basal melting in sea level projections are undermined by poor understanding of the turbulent ice shelf–ocean boundary layer (ISOBL), a meters-thick layer of ocean that regulates heat and salt transfer between the ocean and ice. To address this shortcoming, we perform large-eddy simulations of the ISOBL formed by a steady, geostrophic flow beneath horizontal ice. We investigate melting and ISOBL structure and properties over a range of free-stream velocities and ocean temperatures. We find that the melting response to changes in thermal and current forcing is highly nonlinear due to the effects of meltwater on ISOBL turbulence. Three distinct ISOBL regimes emerge depending on the relative strength of current shear and buoyancy forcing: “well-mixed,” “stratified,” or “diffusive-convective.” We present expressions for mixing-layer depth for each regime and show that the transitions between regimes can be predicted with simple nondimensional parameters. We use these results to develop a novel regime diagram for the ISOBL which provides insight into the varied melting responses expected around Antarctica and highlights the need to include stratified and diffusive-convective dynamics in future basal melting parameterizations. We emphasize that melting in the diffusive-convective regime is time dependent and is therefore inherently difficult to parameterize. Significance Statement The purpose of this study is to investigate the processes that control ocean-driven melting of Antarctic ice shelves (100–1000-m-thick floating extensions of the Antarctic ice sheet). Currently, these processes are poorly understood due to the difficulty of accessing the ocean beneath ice shelves. Using an ocean model, we determine the melting response to different ocean conditions, including feedbacks whereby cold, fresh meltwater can enhance or suppress turbulent eddies beneath the ... |
format |
Article in Journal/Newspaper |
author |
Rosevear, MG Gayen, B Galton-Fenzi, BK |
spellingShingle |
Rosevear, MG Gayen, B Galton-Fenzi, BK Regimes and Transitions in the Basal Melting of Antarctic Ice Shelves |
author_facet |
Rosevear, MG Gayen, B Galton-Fenzi, BK |
author_sort |
Rosevear, MG |
title |
Regimes and Transitions in the Basal Melting of Antarctic Ice Shelves |
title_short |
Regimes and Transitions in the Basal Melting of Antarctic Ice Shelves |
title_full |
Regimes and Transitions in the Basal Melting of Antarctic Ice Shelves |
title_fullStr |
Regimes and Transitions in the Basal Melting of Antarctic Ice Shelves |
title_full_unstemmed |
Regimes and Transitions in the Basal Melting of Antarctic Ice Shelves |
title_sort |
regimes and transitions in the basal melting of antarctic ice shelves |
publisher |
AMER METEOROLOGICAL SOC |
publishDate |
2022 |
url |
http://hdl.handle.net/11343/333537 |
geographic |
Antarctic The Antarctic |
geographic_facet |
Antarctic The Antarctic |
genre |
Antarc* Antarctic Antarctica Ice Sheet Ice Shelf Ice Shelves |
genre_facet |
Antarc* Antarctic Antarctica Ice Sheet Ice Shelf Ice Shelves |
op_relation |
issn:0022-3670 doi:10.1175/JPO-D-21-0317.1 Rosevear, M. G., Gayen, B. & Galton-Fenzi, B. K. (2022). Regimes and Transitions in the Basal Melting of Antarctic Ice Shelves. JOURNAL OF PHYSICAL OCEANOGRAPHY, 52 (10), pp.2589-2608. https://doi.org/10.1175/JPO-D-21-0317.1. 1520-0485 http://hdl.handle.net/11343/333537 |
op_doi |
https://doi.org/10.1175/JPO-D-21-0317.1 |
container_title |
Journal of Physical Oceanography |
container_volume |
52 |
container_issue |
10 |
container_start_page |
2589 |
op_container_end_page |
2608 |
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1800742205705420800 |