Rapid changes in the Subpolar Gyre based on an Ocean General Circulation Model
Data from the ocean component of the Norwegian Earth System Model has been analyzed for the period 1960-2008. Most attention is given to the Subpolar Gyre, which strength and spatial extensiveness is understood to have major consequences for the marine climate in the North Atlantic. Variations in th...
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The University of Bergen
2013
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ftunivbergen:oai:bora.uib.no:1956/6932 2023-05-15T17:06:07+02:00 Rapid changes in the Subpolar Gyre based on an Ocean General Circulation Model Blesvik, Torgeir Hauge 2013-08-08T13:21:38Z 3304379 bytes application/pdf https://hdl.handle.net/1956/6932 eng eng The University of Bergen https://hdl.handle.net/1956/6932 Copyright the author. All rights reserved Master thesis 2013 ftunivbergen 2023-03-14T17:41:05Z Data from the ocean component of the Norwegian Earth System Model has been analyzed for the period 1960-2008. Most attention is given to the Subpolar Gyre, which strength and spatial extensiveness is understood to have major consequences for the marine climate in the North Atlantic. Variations in the ocean temperature and salinity are mainly found in the upper few hundred meters, to a large degree dictated by the atmospheric forcing. The Labrador Sea is the region which shows largest response to the atmospheric forcing, and is a major source for variations in the Atlantic Meridional Ocean Circulation at 41\(^{\circ}\)N. In the Labrador Sea, the convective mixing during strong cooling events reaches down to 2000-2500 m and increases the thickness of the isopycnic layer of potential density 1036.843 kg m\)^{-3}\) (relative to 2000 m depth) by approximately 500 m relative to the climatological mean value. This water mass more than double in volume between a minimum in 1970 and a maximum in 1995. Using an idealised model and Margules relation, we have shown that a 5 Sverdrup (1 Sv \(= 10^6\) m\(^3\) s\(^{-1}\)) intensification of the barotropic streamfunction for strong versus normal years expressed in terms of the North Atlantic Oscillation (NAO) index is consistent with roughly an increase in the geostrophic flow of 15\%. Using composites from a NAO index derived from two-station and spatial pattern-based sea level pressure differences show negligible to large differences in the upper ocean response to the atmospheric forcing, depending on the actual analyzes examined. MAMN-GEOF GEOF399 Master Thesis Labrador Sea North Atlantic North Atlantic oscillation University of Bergen: Bergen Open Research Archive (BORA-UiB) |
institution |
Open Polar |
collection |
University of Bergen: Bergen Open Research Archive (BORA-UiB) |
op_collection_id |
ftunivbergen |
language |
English |
description |
Data from the ocean component of the Norwegian Earth System Model has been analyzed for the period 1960-2008. Most attention is given to the Subpolar Gyre, which strength and spatial extensiveness is understood to have major consequences for the marine climate in the North Atlantic. Variations in the ocean temperature and salinity are mainly found in the upper few hundred meters, to a large degree dictated by the atmospheric forcing. The Labrador Sea is the region which shows largest response to the atmospheric forcing, and is a major source for variations in the Atlantic Meridional Ocean Circulation at 41\(^{\circ}\)N. In the Labrador Sea, the convective mixing during strong cooling events reaches down to 2000-2500 m and increases the thickness of the isopycnic layer of potential density 1036.843 kg m\)^{-3}\) (relative to 2000 m depth) by approximately 500 m relative to the climatological mean value. This water mass more than double in volume between a minimum in 1970 and a maximum in 1995. Using an idealised model and Margules relation, we have shown that a 5 Sverdrup (1 Sv \(= 10^6\) m\(^3\) s\(^{-1}\)) intensification of the barotropic streamfunction for strong versus normal years expressed in terms of the North Atlantic Oscillation (NAO) index is consistent with roughly an increase in the geostrophic flow of 15\%. Using composites from a NAO index derived from two-station and spatial pattern-based sea level pressure differences show negligible to large differences in the upper ocean response to the atmospheric forcing, depending on the actual analyzes examined. MAMN-GEOF GEOF399 |
format |
Master Thesis |
author |
Blesvik, Torgeir Hauge |
spellingShingle |
Blesvik, Torgeir Hauge Rapid changes in the Subpolar Gyre based on an Ocean General Circulation Model |
author_facet |
Blesvik, Torgeir Hauge |
author_sort |
Blesvik, Torgeir Hauge |
title |
Rapid changes in the Subpolar Gyre based on an Ocean General Circulation Model |
title_short |
Rapid changes in the Subpolar Gyre based on an Ocean General Circulation Model |
title_full |
Rapid changes in the Subpolar Gyre based on an Ocean General Circulation Model |
title_fullStr |
Rapid changes in the Subpolar Gyre based on an Ocean General Circulation Model |
title_full_unstemmed |
Rapid changes in the Subpolar Gyre based on an Ocean General Circulation Model |
title_sort |
rapid changes in the subpolar gyre based on an ocean general circulation model |
publisher |
The University of Bergen |
publishDate |
2013 |
url |
https://hdl.handle.net/1956/6932 |
genre |
Labrador Sea North Atlantic North Atlantic oscillation |
genre_facet |
Labrador Sea North Atlantic North Atlantic oscillation |
op_relation |
https://hdl.handle.net/1956/6932 |
op_rights |
Copyright the author. All rights reserved |
_version_ |
1766061100708659200 |