Impact of Deep Water Formation on Antarctic Circumpolar Transport During Gateway Opening
Ambiguity over the Eocene opening times of the Tasman Gateway and Drake Passage makes it difficult to determine the initiation time of the Antarctic Circumpolar Current (ACC). If the Tasman Gateway opened later than Drake Passage, then Australia may have prevented the proto-ACC from forming. Recent...
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crwinnower:10.22541/essoar.167160849.98375746/v1 2024-06-02T07:57:08+00:00 Impact of Deep Water Formation on Antarctic Circumpolar Transport During Gateway Opening Munday, David R Sauermilch, Isabel Klocker, Andreas Whittaker, Joanne M 2022 http://dx.doi.org/10.22541/essoar.167160849.98375746/v1 unknown Authorea, Inc. posted-content 2022 crwinnower https://doi.org/10.22541/essoar.167160849.98375746/v1 2024-05-07T14:19:24Z Ambiguity over the Eocene opening times of the Tasman Gateway and Drake Passage makes it difficult to determine the initiation time of the Antarctic Circumpolar Current (ACC). If the Tasman Gateway opened later than Drake Passage, then Australia may have prevented the proto-ACC from forming. Recent modelling results have shown that only a relatively weak circumpolar transport results under Eocene surface forcing. This leads to warm and buoyant coastal water around Antarctica, which may impede the formation of deep waters and convective processes. This suggests that a change in deep water formation might be required to increase the density contrast across the Southern Ocean and increase circumpolar transport.Here we use a simple reduced gravity model with two basins, to represent the Atlantic and the Pacific. This fixes the density difference between surface and deep water and allows us to isolate the impact of deep water formation on circumpolar transport. With no obstacle on the southern boundary the circumpolar current increases its transport from 82.3 to 270.0 Sv with deep water formation. Placing an Antipodean landmass on the southern boundary reduces this transport as the landmass increases in size. However, circumpolar flow north of this landmass remains a possibility even without deep water formation. Weak circumpolar transport continues until the basin is completely blocked by the Antipodes. When the Antipodes is instead allowed to split from the southern boundary, circumpolar transport recovers to its unobstructed value. Flow rapidly switches to south of the Antipodes when the gateway is narrow. Other/Unknown Material Antarc* Antarctic Antarctica Drake Passage Southern Ocean The Winnower Antarctic Drake Passage Pacific Southern Ocean The Antarctic |
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Ambiguity over the Eocene opening times of the Tasman Gateway and Drake Passage makes it difficult to determine the initiation time of the Antarctic Circumpolar Current (ACC). If the Tasman Gateway opened later than Drake Passage, then Australia may have prevented the proto-ACC from forming. Recent modelling results have shown that only a relatively weak circumpolar transport results under Eocene surface forcing. This leads to warm and buoyant coastal water around Antarctica, which may impede the formation of deep waters and convective processes. This suggests that a change in deep water formation might be required to increase the density contrast across the Southern Ocean and increase circumpolar transport.Here we use a simple reduced gravity model with two basins, to represent the Atlantic and the Pacific. This fixes the density difference between surface and deep water and allows us to isolate the impact of deep water formation on circumpolar transport. With no obstacle on the southern boundary the circumpolar current increases its transport from 82.3 to 270.0 Sv with deep water formation. Placing an Antipodean landmass on the southern boundary reduces this transport as the landmass increases in size. However, circumpolar flow north of this landmass remains a possibility even without deep water formation. Weak circumpolar transport continues until the basin is completely blocked by the Antipodes. When the Antipodes is instead allowed to split from the southern boundary, circumpolar transport recovers to its unobstructed value. Flow rapidly switches to south of the Antipodes when the gateway is narrow. |
format |
Other/Unknown Material |
author |
Munday, David R Sauermilch, Isabel Klocker, Andreas Whittaker, Joanne M |
spellingShingle |
Munday, David R Sauermilch, Isabel Klocker, Andreas Whittaker, Joanne M Impact of Deep Water Formation on Antarctic Circumpolar Transport During Gateway Opening |
author_facet |
Munday, David R Sauermilch, Isabel Klocker, Andreas Whittaker, Joanne M |
author_sort |
Munday, David R |
title |
Impact of Deep Water Formation on Antarctic Circumpolar Transport During Gateway Opening |
title_short |
Impact of Deep Water Formation on Antarctic Circumpolar Transport During Gateway Opening |
title_full |
Impact of Deep Water Formation on Antarctic Circumpolar Transport During Gateway Opening |
title_fullStr |
Impact of Deep Water Formation on Antarctic Circumpolar Transport During Gateway Opening |
title_full_unstemmed |
Impact of Deep Water Formation on Antarctic Circumpolar Transport During Gateway Opening |
title_sort |
impact of deep water formation on antarctic circumpolar transport during gateway opening |
publisher |
Authorea, Inc. |
publishDate |
2022 |
url |
http://dx.doi.org/10.22541/essoar.167160849.98375746/v1 |
geographic |
Antarctic Drake Passage Pacific Southern Ocean The Antarctic |
geographic_facet |
Antarctic Drake Passage Pacific Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Antarctica Drake Passage Southern Ocean |
genre_facet |
Antarc* Antarctic Antarctica Drake Passage Southern Ocean |
op_doi |
https://doi.org/10.22541/essoar.167160849.98375746/v1 |
_version_ |
1800739130226769920 |