Bifurcation of potential vorticity gradients across the Southern Hemisphere stratospheric polar vortex
The wintertime stratospheric westerly winds circling the Antarctic continent, also known as the Southern Hemisphere polar vortex, create a barrier to mixing of air between middle and high latitudes. This dynamical isolation has important consequences for export of ozone-depleted air from the Antarct...
Published in: | Atmospheric Chemistry and Physics |
---|---|
Main Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Copernicus Publications
2018
|
Subjects: | |
Online Access: | https://doi.org/10.5194/acp-18-8065-2018 https://noa.gwlb.de/receive/cop_mods_00041712 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00041332/acp-18-8065-2018.pdf https://acp.copernicus.org/articles/18/8065/2018/acp-18-8065-2018.pdf |
id |
ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00041712 |
---|---|
record_format |
openpolar |
spelling |
ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00041712 2023-05-15T14:02:33+02:00 Bifurcation of potential vorticity gradients across the Southern Hemisphere stratospheric polar vortex Conway, Jonathan Bodeker, Greg Cameron, Chris 2018-06 electronic https://doi.org/10.5194/acp-18-8065-2018 https://noa.gwlb.de/receive/cop_mods_00041712 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00041332/acp-18-8065-2018.pdf https://acp.copernicus.org/articles/18/8065/2018/acp-18-8065-2018.pdf eng eng Copernicus Publications Atmospheric Chemistry and Physics -- http://www.atmos-chem-phys.net/volumes_and_issues.html -- http://www.bibliothek.uni-regensburg.de/ezeit/?2069847 -- 1680-7324 https://doi.org/10.5194/acp-18-8065-2018 https://noa.gwlb.de/receive/cop_mods_00041712 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00041332/acp-18-8065-2018.pdf https://acp.copernicus.org/articles/18/8065/2018/acp-18-8065-2018.pdf https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess CC-BY article Verlagsveröffentlichung article Text doc-type:article 2018 ftnonlinearchiv https://doi.org/10.5194/acp-18-8065-2018 2022-02-08T22:41:25Z The wintertime stratospheric westerly winds circling the Antarctic continent, also known as the Southern Hemisphere polar vortex, create a barrier to mixing of air between middle and high latitudes. This dynamical isolation has important consequences for export of ozone-depleted air from the Antarctic stratosphere to lower latitudes. The prevailing view of this dynamical barrier has been an annulus compromising steep gradients of potential vorticity (PV) that create a single semi-permeable barrier to mixing. Analyses presented here show that this barrier often displays a bifurcated structure where a double-walled barrier exists. The bifurcated structure manifests as enhanced gradients of PV at two distinct latitudes – usually on the inside and outside flanks of the region of highest wind speed. Metrics that quantify the bifurcated nature of the vortex have been developed and their variation in space and time has been analysed. At most isentropic levels between 395 and 850 K, bifurcation is strongest in mid-winter and decreases dramatically during spring. From August onwards a distinct structure emerges, where elevated bifurcation remains between 475 and 600 K, and a mostly single-walled barrier occurs at other levels. While bifurcation at a given level evolves from month to month, and does not always persist through a season, interannual variations in the strength of bifurcation display coherence across multiple levels in any given month. Accounting for bifurcation allows the region of reduced mixing to be better characterised. These results suggest that improved understanding of cross-vortex mixing requires consideration of the polar vortex not as a single mixing barrier but as a barrier with internal structure that is likely to manifest as more complex gradients in trace gas concentrations across the vortex barrier region. Article in Journal/Newspaper Antarc* Antarctic Niedersächsisches Online-Archiv NOA Antarctic The Antarctic Atmospheric Chemistry and Physics 18 11 8065 8077 |
institution |
Open Polar |
collection |
Niedersächsisches Online-Archiv NOA |
op_collection_id |
ftnonlinearchiv |
language |
English |
topic |
article Verlagsveröffentlichung |
spellingShingle |
article Verlagsveröffentlichung Conway, Jonathan Bodeker, Greg Cameron, Chris Bifurcation of potential vorticity gradients across the Southern Hemisphere stratospheric polar vortex |
topic_facet |
article Verlagsveröffentlichung |
description |
The wintertime stratospheric westerly winds circling the Antarctic continent, also known as the Southern Hemisphere polar vortex, create a barrier to mixing of air between middle and high latitudes. This dynamical isolation has important consequences for export of ozone-depleted air from the Antarctic stratosphere to lower latitudes. The prevailing view of this dynamical barrier has been an annulus compromising steep gradients of potential vorticity (PV) that create a single semi-permeable barrier to mixing. Analyses presented here show that this barrier often displays a bifurcated structure where a double-walled barrier exists. The bifurcated structure manifests as enhanced gradients of PV at two distinct latitudes – usually on the inside and outside flanks of the region of highest wind speed. Metrics that quantify the bifurcated nature of the vortex have been developed and their variation in space and time has been analysed. At most isentropic levels between 395 and 850 K, bifurcation is strongest in mid-winter and decreases dramatically during spring. From August onwards a distinct structure emerges, where elevated bifurcation remains between 475 and 600 K, and a mostly single-walled barrier occurs at other levels. While bifurcation at a given level evolves from month to month, and does not always persist through a season, interannual variations in the strength of bifurcation display coherence across multiple levels in any given month. Accounting for bifurcation allows the region of reduced mixing to be better characterised. These results suggest that improved understanding of cross-vortex mixing requires consideration of the polar vortex not as a single mixing barrier but as a barrier with internal structure that is likely to manifest as more complex gradients in trace gas concentrations across the vortex barrier region. |
format |
Article in Journal/Newspaper |
author |
Conway, Jonathan Bodeker, Greg Cameron, Chris |
author_facet |
Conway, Jonathan Bodeker, Greg Cameron, Chris |
author_sort |
Conway, Jonathan |
title |
Bifurcation of potential vorticity gradients across the Southern Hemisphere stratospheric polar vortex |
title_short |
Bifurcation of potential vorticity gradients across the Southern Hemisphere stratospheric polar vortex |
title_full |
Bifurcation of potential vorticity gradients across the Southern Hemisphere stratospheric polar vortex |
title_fullStr |
Bifurcation of potential vorticity gradients across the Southern Hemisphere stratospheric polar vortex |
title_full_unstemmed |
Bifurcation of potential vorticity gradients across the Southern Hemisphere stratospheric polar vortex |
title_sort |
bifurcation of potential vorticity gradients across the southern hemisphere stratospheric polar vortex |
publisher |
Copernicus Publications |
publishDate |
2018 |
url |
https://doi.org/10.5194/acp-18-8065-2018 https://noa.gwlb.de/receive/cop_mods_00041712 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00041332/acp-18-8065-2018.pdf https://acp.copernicus.org/articles/18/8065/2018/acp-18-8065-2018.pdf |
geographic |
Antarctic The Antarctic |
geographic_facet |
Antarctic The Antarctic |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_relation |
Atmospheric Chemistry and Physics -- http://www.atmos-chem-phys.net/volumes_and_issues.html -- http://www.bibliothek.uni-regensburg.de/ezeit/?2069847 -- 1680-7324 https://doi.org/10.5194/acp-18-8065-2018 https://noa.gwlb.de/receive/cop_mods_00041712 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00041332/acp-18-8065-2018.pdf https://acp.copernicus.org/articles/18/8065/2018/acp-18-8065-2018.pdf |
op_rights |
https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.5194/acp-18-8065-2018 |
container_title |
Atmospheric Chemistry and Physics |
container_volume |
18 |
container_issue |
11 |
container_start_page |
8065 |
op_container_end_page |
8077 |
_version_ |
1766272863194578944 |