When do marginal seas and topographic sills modify the ocean density structure?
We ask what effect marginal seas at high latitudes have on the abyssal densities and stratification of the oceans. Although marginal seas are not necessary for the formation of dense abyssal waters, topographic sills tend to restrict exchange flows and increase density differences. Laboratory experi...
Main Authors: | , , |
---|---|
Format: | Article in Journal/Newspaper |
Language: | unknown |
Published: |
American Geophysical Union
2015
|
Subjects: | |
Online Access: | http://hdl.handle.net/1885/37854 |
id |
ftanucanberra:oai:digitalcollections.anu.edu.au:1885/37854 |
---|---|
record_format |
openpolar |
spelling |
ftanucanberra:oai:digitalcollections.anu.edu.au:1885/37854 2023-05-15T16:28:08+02:00 When do marginal seas and topographic sills modify the ocean density structure? Stewart, Kial Hughes, Graham Griffiths, Ross 2015-12-08T22:45:44Z http://hdl.handle.net/1885/37854 unknown American Geophysical Union 0148-0227 http://hdl.handle.net/1885/37854 Journal of Geophysical Research Journal article 2015 ftanucanberra 2015-12-28T23:25:54Z We ask what effect marginal seas at high latitudes have on the abyssal densities and stratification of the oceans. Although marginal seas are not necessary for the formation of dense abyssal waters, topographic sills tend to restrict exchange flows and increase density differences. Laboratory experiments with a steady state large-scale overturning circulation, forced by a gradient in surface temperatures or heat fluxes, show that a marginal sea and topographic sill influence the abyssal density when the sill depth is less than twice the oceanic thermocline depth. The overflow over shallow sills interacts directly with the surrounding thermocline stratification, decreasing the abyssal density relative to an ocean with no marginal sea and increasing the density difference between the sea and the ocean. Experiments show that the effect of the sill depends on the surface boundary conditions and indicate a larger response for conditions approaching a prescribed distribution of temperature rather than of heat flux. Application of the results to the North Atlantic circulation suggests that the Greenland-Scotland Ridge is shallow enough to lead to a significant reduction of the density of North Atlantic Deep Water, and this is consistent with the conclusions from an analysis of water mass properties. The Greenland-Scotland Ridge is therefore likely to have a significant effect on the density structure and heat transport in the global oceans. Article in Journal/Newspaper Greenland Greenland-Scotland Ridge North Atlantic Deep Water North Atlantic Australian National University: ANU Digital Collections Greenland |
institution |
Open Polar |
collection |
Australian National University: ANU Digital Collections |
op_collection_id |
ftanucanberra |
language |
unknown |
description |
We ask what effect marginal seas at high latitudes have on the abyssal densities and stratification of the oceans. Although marginal seas are not necessary for the formation of dense abyssal waters, topographic sills tend to restrict exchange flows and increase density differences. Laboratory experiments with a steady state large-scale overturning circulation, forced by a gradient in surface temperatures or heat fluxes, show that a marginal sea and topographic sill influence the abyssal density when the sill depth is less than twice the oceanic thermocline depth. The overflow over shallow sills interacts directly with the surrounding thermocline stratification, decreasing the abyssal density relative to an ocean with no marginal sea and increasing the density difference between the sea and the ocean. Experiments show that the effect of the sill depends on the surface boundary conditions and indicate a larger response for conditions approaching a prescribed distribution of temperature rather than of heat flux. Application of the results to the North Atlantic circulation suggests that the Greenland-Scotland Ridge is shallow enough to lead to a significant reduction of the density of North Atlantic Deep Water, and this is consistent with the conclusions from an analysis of water mass properties. The Greenland-Scotland Ridge is therefore likely to have a significant effect on the density structure and heat transport in the global oceans. |
format |
Article in Journal/Newspaper |
author |
Stewart, Kial Hughes, Graham Griffiths, Ross |
spellingShingle |
Stewart, Kial Hughes, Graham Griffiths, Ross When do marginal seas and topographic sills modify the ocean density structure? |
author_facet |
Stewart, Kial Hughes, Graham Griffiths, Ross |
author_sort |
Stewart, Kial |
title |
When do marginal seas and topographic sills modify the ocean density structure? |
title_short |
When do marginal seas and topographic sills modify the ocean density structure? |
title_full |
When do marginal seas and topographic sills modify the ocean density structure? |
title_fullStr |
When do marginal seas and topographic sills modify the ocean density structure? |
title_full_unstemmed |
When do marginal seas and topographic sills modify the ocean density structure? |
title_sort |
when do marginal seas and topographic sills modify the ocean density structure? |
publisher |
American Geophysical Union |
publishDate |
2015 |
url |
http://hdl.handle.net/1885/37854 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Greenland-Scotland Ridge North Atlantic Deep Water North Atlantic |
genre_facet |
Greenland Greenland-Scotland Ridge North Atlantic Deep Water North Atlantic |
op_source |
Journal of Geophysical Research |
op_relation |
0148-0227 http://hdl.handle.net/1885/37854 |
_version_ |
1766017757735813120 |