The effect of changing Southern Hemisphere winter sea surface temperatures on Southern Annular Mode strength
We examine the impact that changes in the winter Southern Hemisphere (SH) meridional sea surface temperature (SST) gradient have on the sign and strength of the SH Annular Mode (SAM). This is undertaken by perturbing either tropical or extra-tropical SSTs in an atmospheric General Circulation Model....
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American Geophysical Union
2006
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ftnerc:oai:nora.nerc.ac.uk:80 2024-06-09T07:49:44+00:00 The effect of changing Southern Hemisphere winter sea surface temperatures on Southern Annular Mode strength Marshall, Gareth J. Connolley, William M. 2006 http://nora.nerc.ac.uk/id/eprint/80/ unknown American Geophysical Union Marshall, Gareth J. orcid:0000-0001-8887-7314 Connolley, William M. 2006 The effect of changing Southern Hemisphere winter sea surface temperatures on Southern Annular Mode strength. Geophysical Research Letters, 33 (17), L17717. 4, pp. https://doi.org/10.1029/2006GL026627 <https://doi.org/10.1029/2006GL026627> Atmospheric Sciences Publication - Article PeerReviewed 2006 ftnerc https://doi.org/10.1029/2006GL026627 2024-05-15T08:39:04Z We examine the impact that changes in the winter Southern Hemisphere (SH) meridional sea surface temperature (SST) gradient have on the sign and strength of the SH Annular Mode (SAM). This is undertaken by perturbing either tropical or extra-tropical SSTs in an atmospheric General Circulation Model. Changes in winter tropical SSTs have little direct influence on the SAM but do force a strong wave train in geopotential height across the Southern Ocean. In contrast, changes in winter SSTs in the SH extra-tropics have a profound effect on the SAM: cooler SSTs strengthen the SAM and vice versa. The mechanism involves modifications to the Ferrel cell. As a positive (negative) SAM enhances (reduces) the extra-tropical meridional temperature gradient, these experiments demonstrate a positive feedback mechanism. SAM variability remains unchanged, indicating a shift in the mean, rather than a change in the probability distribution of its positive and negative phases Article in Journal/Newspaper Southern Ocean Natural Environment Research Council: NERC Open Research Archive Southern Ocean Geophysical Research Letters 33 17 |
institution |
Open Polar |
collection |
Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
unknown |
topic |
Atmospheric Sciences |
spellingShingle |
Atmospheric Sciences Marshall, Gareth J. Connolley, William M. The effect of changing Southern Hemisphere winter sea surface temperatures on Southern Annular Mode strength |
topic_facet |
Atmospheric Sciences |
description |
We examine the impact that changes in the winter Southern Hemisphere (SH) meridional sea surface temperature (SST) gradient have on the sign and strength of the SH Annular Mode (SAM). This is undertaken by perturbing either tropical or extra-tropical SSTs in an atmospheric General Circulation Model. Changes in winter tropical SSTs have little direct influence on the SAM but do force a strong wave train in geopotential height across the Southern Ocean. In contrast, changes in winter SSTs in the SH extra-tropics have a profound effect on the SAM: cooler SSTs strengthen the SAM and vice versa. The mechanism involves modifications to the Ferrel cell. As a positive (negative) SAM enhances (reduces) the extra-tropical meridional temperature gradient, these experiments demonstrate a positive feedback mechanism. SAM variability remains unchanged, indicating a shift in the mean, rather than a change in the probability distribution of its positive and negative phases |
format |
Article in Journal/Newspaper |
author |
Marshall, Gareth J. Connolley, William M. |
author_facet |
Marshall, Gareth J. Connolley, William M. |
author_sort |
Marshall, Gareth J. |
title |
The effect of changing Southern Hemisphere winter sea surface temperatures on Southern Annular Mode strength |
title_short |
The effect of changing Southern Hemisphere winter sea surface temperatures on Southern Annular Mode strength |
title_full |
The effect of changing Southern Hemisphere winter sea surface temperatures on Southern Annular Mode strength |
title_fullStr |
The effect of changing Southern Hemisphere winter sea surface temperatures on Southern Annular Mode strength |
title_full_unstemmed |
The effect of changing Southern Hemisphere winter sea surface temperatures on Southern Annular Mode strength |
title_sort |
effect of changing southern hemisphere winter sea surface temperatures on southern annular mode strength |
publisher |
American Geophysical Union |
publishDate |
2006 |
url |
http://nora.nerc.ac.uk/id/eprint/80/ |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_relation |
Marshall, Gareth J. orcid:0000-0001-8887-7314 Connolley, William M. 2006 The effect of changing Southern Hemisphere winter sea surface temperatures on Southern Annular Mode strength. Geophysical Research Letters, 33 (17), L17717. 4, pp. https://doi.org/10.1029/2006GL026627 <https://doi.org/10.1029/2006GL026627> |
op_doi |
https://doi.org/10.1029/2006GL026627 |
container_title |
Geophysical Research Letters |
container_volume |
33 |
container_issue |
17 |
_version_ |
1801382534123094016 |