Reversal of ocean gyres near ice shelves in the Amundsen Sea caused by the interaction of sea ice and wind
Floating ice shelves buttress the Antarctic Ice Sheet, which is losing mass rapidly mainly due to ocean-driven melting and the associated disruption to glacial dynamics. The local ocean circulation near ice shelves is therefore important for the prediction of future ice mass loss and related sea-lev...
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Copernicus Publications
2022
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ftdoajarticles:oai:doaj.org/article:6f0c8d7148ef45998665ecea825af577 2023-05-15T13:24:17+02:00 Reversal of ocean gyres near ice shelves in the Amundsen Sea caused by the interaction of sea ice and wind Y. Zheng D. P. Stevens K. J. Heywood B. G. M. Webber B. Y. Queste 2022-07-01T00:00:00Z https://doi.org/10.5194/tc-16-3005-2022 https://doaj.org/article/6f0c8d7148ef45998665ecea825af577 EN eng Copernicus Publications https://tc.copernicus.org/articles/16/3005/2022/tc-16-3005-2022.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-16-3005-2022 1994-0416 1994-0424 https://doaj.org/article/6f0c8d7148ef45998665ecea825af577 The Cryosphere, Vol 16, Pp 3005-3019 (2022) Environmental sciences GE1-350 Geology QE1-996.5 article 2022 ftdoajarticles https://doi.org/10.5194/tc-16-3005-2022 2022-12-31T00:48:01Z Floating ice shelves buttress the Antarctic Ice Sheet, which is losing mass rapidly mainly due to ocean-driven melting and the associated disruption to glacial dynamics. The local ocean circulation near ice shelves is therefore important for the prediction of future ice mass loss and related sea-level rise as it determines the water mass exchange, heat transport under the ice shelf and resultant melting. However, the dynamics controlling the near-coastal circulation are not fully understood. A cyclonic (i.e. clockwise) gyre circulation (27 km radius) in front of the Pine Island Ice Shelf has previously been identified in both numerical models and velocity observations. Mooring data further revealed a potential reversal of this gyre during an abnormally cold period. Here we present ship-based observations from 2019 to the west of Thwaites Ice Shelf, revealing another gyre (13 km radius) for the first time in this habitually ice-covered region, rotating in the opposite (anticyclonic, anticlockwise) direction to the gyre near Pine Island Ice Shelf, despite similar wind forcing. We use an idealised configuration of MITgcm, with idealised forcing based on ERA5 climatological wind fields and a range of idealised sea ice conditions typical for the region, to reproduce key features of the observed gyres near Pine Island Ice Shelf and Thwaites Ice Shelf. The model driven solely by wind forcing in the presence of ice can reproduce the horizontal structure and direction of both gyres. We show that the modelled gyre direction depends upon the spatial difference in the ocean surface stress, which can be affected by the applied wind stress curl filed, the percentage of wind stress transferred through the ice, and the angle between the wind direction and the sea ice edge. The presence of ice, either it is fast ice/ice shelves blocking the effect of wind or mobile sea ice enhancing the effect of wind, has the potential to reverse the gyre direction relative to ice-free conditions. Article in Journal/Newspaper Amundsen Sea Antarc* Antarctic Ice Sheet Ice Shelf Ice Shelves Sea ice The Cryosphere Thwaites Ice Shelf Directory of Open Access Journals: DOAJ Articles Antarctic The Antarctic Amundsen Sea Curl ENVELOPE(-63.071,-63.071,-70.797,-70.797) Buttress ENVELOPE(-57.083,-57.083,-63.550,-63.550) The Cryosphere 16 7 3005 3019 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
spellingShingle |
Environmental sciences GE1-350 Geology QE1-996.5 Y. Zheng D. P. Stevens K. J. Heywood B. G. M. Webber B. Y. Queste Reversal of ocean gyres near ice shelves in the Amundsen Sea caused by the interaction of sea ice and wind |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
Floating ice shelves buttress the Antarctic Ice Sheet, which is losing mass rapidly mainly due to ocean-driven melting and the associated disruption to glacial dynamics. The local ocean circulation near ice shelves is therefore important for the prediction of future ice mass loss and related sea-level rise as it determines the water mass exchange, heat transport under the ice shelf and resultant melting. However, the dynamics controlling the near-coastal circulation are not fully understood. A cyclonic (i.e. clockwise) gyre circulation (27 km radius) in front of the Pine Island Ice Shelf has previously been identified in both numerical models and velocity observations. Mooring data further revealed a potential reversal of this gyre during an abnormally cold period. Here we present ship-based observations from 2019 to the west of Thwaites Ice Shelf, revealing another gyre (13 km radius) for the first time in this habitually ice-covered region, rotating in the opposite (anticyclonic, anticlockwise) direction to the gyre near Pine Island Ice Shelf, despite similar wind forcing. We use an idealised configuration of MITgcm, with idealised forcing based on ERA5 climatological wind fields and a range of idealised sea ice conditions typical for the region, to reproduce key features of the observed gyres near Pine Island Ice Shelf and Thwaites Ice Shelf. The model driven solely by wind forcing in the presence of ice can reproduce the horizontal structure and direction of both gyres. We show that the modelled gyre direction depends upon the spatial difference in the ocean surface stress, which can be affected by the applied wind stress curl filed, the percentage of wind stress transferred through the ice, and the angle between the wind direction and the sea ice edge. The presence of ice, either it is fast ice/ice shelves blocking the effect of wind or mobile sea ice enhancing the effect of wind, has the potential to reverse the gyre direction relative to ice-free conditions. |
format |
Article in Journal/Newspaper |
author |
Y. Zheng D. P. Stevens K. J. Heywood B. G. M. Webber B. Y. Queste |
author_facet |
Y. Zheng D. P. Stevens K. J. Heywood B. G. M. Webber B. Y. Queste |
author_sort |
Y. Zheng |
title |
Reversal of ocean gyres near ice shelves in the Amundsen Sea caused by the interaction of sea ice and wind |
title_short |
Reversal of ocean gyres near ice shelves in the Amundsen Sea caused by the interaction of sea ice and wind |
title_full |
Reversal of ocean gyres near ice shelves in the Amundsen Sea caused by the interaction of sea ice and wind |
title_fullStr |
Reversal of ocean gyres near ice shelves in the Amundsen Sea caused by the interaction of sea ice and wind |
title_full_unstemmed |
Reversal of ocean gyres near ice shelves in the Amundsen Sea caused by the interaction of sea ice and wind |
title_sort |
reversal of ocean gyres near ice shelves in the amundsen sea caused by the interaction of sea ice and wind |
publisher |
Copernicus Publications |
publishDate |
2022 |
url |
https://doi.org/10.5194/tc-16-3005-2022 https://doaj.org/article/6f0c8d7148ef45998665ecea825af577 |
long_lat |
ENVELOPE(-63.071,-63.071,-70.797,-70.797) ENVELOPE(-57.083,-57.083,-63.550,-63.550) |
geographic |
Antarctic The Antarctic Amundsen Sea Curl Buttress |
geographic_facet |
Antarctic The Antarctic Amundsen Sea Curl Buttress |
genre |
Amundsen Sea Antarc* Antarctic Ice Sheet Ice Shelf Ice Shelves Sea ice The Cryosphere Thwaites Ice Shelf |
genre_facet |
Amundsen Sea Antarc* Antarctic Ice Sheet Ice Shelf Ice Shelves Sea ice The Cryosphere Thwaites Ice Shelf |
op_source |
The Cryosphere, Vol 16, Pp 3005-3019 (2022) |
op_relation |
https://tc.copernicus.org/articles/16/3005/2022/tc-16-3005-2022.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-16-3005-2022 1994-0416 1994-0424 https://doaj.org/article/6f0c8d7148ef45998665ecea825af577 |
op_doi |
https://doi.org/10.5194/tc-16-3005-2022 |
container_title |
The Cryosphere |
container_volume |
16 |
container_issue |
7 |
container_start_page |
3005 |
op_container_end_page |
3019 |
_version_ |
1766378555931885568 |