Extratropical circulation indices in the Southern Hemisphere based on station data

Zonal and meridional pressure gradient indices of the Southern Hemisphere (SH) circulation are analysed in the mid-to-high (35-65°S) latitude zone. The dearth of land regions, and hence long pressure records, means that these are restricted to the southern South American and New Zealand sectors. The...

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Main Authors: Jones, PD, Salinger, MJ, Mullan, AB
Format: Article in Journal/Newspaper
Language:unknown
Published: 1999
Subjects:
Online Access:https://ueaeprints.uea.ac.uk/id/eprint/33988/
https://doi.org/10.1002/(SICI)1097-0088(199910)19:12<1301::AID-JOC425>3.0.CO;2-P
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spelling ftuniveastangl:oai:ueaeprints.uea.ac.uk:33988 2023-06-06T11:59:36+02:00 Extratropical circulation indices in the Southern Hemisphere based on station data Jones, PD Salinger, MJ Mullan, AB 1999 https://ueaeprints.uea.ac.uk/id/eprint/33988/ https://doi.org/10.1002/(SICI)1097-0088(199910)19:12<1301::AID-JOC425>3.0.CO;2-P unknown Jones, PD, Salinger, MJ and Mullan, AB (1999) Extratropical circulation indices in the Southern Hemisphere based on station data. International Journal of Climatology, 19 (12). pp. 1301-1317. ISSN 0899-8418 doi:10.1002/(SICI)1097-0088(199910)19:12<1301::AID-JOC425>3.0.CO;2-P Article PeerReviewed 1999 ftuniveastangl https://doi.org/10.1002/(SICI)1097-0088(199910)19:12<1301::AID-JOC425>3.0.CO;2-P 2023-04-13T22:31:36Z Zonal and meridional pressure gradient indices of the Southern Hemisphere (SH) circulation are analysed in the mid-to-high (35-65°S) latitude zone. The dearth of land regions, and hence long pressure records, means that these are restricted to the southern South American and New Zealand sectors. The Trans Polar Index (TPI) is the only large-scale station pressure based extratropical SH index that has been proposed, and is based on the normalised pressure difference between Hobart, Tasmania and Stanley, Falklands. This index is compared with variants which involve stations in the vicinity of New Zealand and southern South America. The index shows considerable year-to-year and some decadal-scale variability and is a measure of wavenumber 1 of the SH pressure field. Significant correlations (r ~ -0.3 to -0.5) occur between the TPI and southern South American temperatures in the austral summer and autumn seasons. Similar size correlations of the opposite sign occur in New Zealand but only in the austral summer season. In New Zealand and southern South America, temperature series are strongly affected by the strength of the local meridional circulation (r values ~ -0.4 to -0.7 over New Zealand depending on season and period and values of ~ -0.2 to -0.4 for southern South America). In both regions there is no concomitant increase in northerly flow or decrease in southerly flow to explain the long-term increase in temperatures. The relationships are mostly at the interannual rather than the decadal and longer timescales. The decadal temperature rise, therefore, reflects a general warming of the Southern Ocean, rather than decadal-scale variations in the circulation. Article in Journal/Newspaper Southern Ocean University of East Anglia: UEA Digital Repository Austral New Zealand Southern Ocean
institution Open Polar
collection University of East Anglia: UEA Digital Repository
op_collection_id ftuniveastangl
language unknown
description Zonal and meridional pressure gradient indices of the Southern Hemisphere (SH) circulation are analysed in the mid-to-high (35-65°S) latitude zone. The dearth of land regions, and hence long pressure records, means that these are restricted to the southern South American and New Zealand sectors. The Trans Polar Index (TPI) is the only large-scale station pressure based extratropical SH index that has been proposed, and is based on the normalised pressure difference between Hobart, Tasmania and Stanley, Falklands. This index is compared with variants which involve stations in the vicinity of New Zealand and southern South America. The index shows considerable year-to-year and some decadal-scale variability and is a measure of wavenumber 1 of the SH pressure field. Significant correlations (r ~ -0.3 to -0.5) occur between the TPI and southern South American temperatures in the austral summer and autumn seasons. Similar size correlations of the opposite sign occur in New Zealand but only in the austral summer season. In New Zealand and southern South America, temperature series are strongly affected by the strength of the local meridional circulation (r values ~ -0.4 to -0.7 over New Zealand depending on season and period and values of ~ -0.2 to -0.4 for southern South America). In both regions there is no concomitant increase in northerly flow or decrease in southerly flow to explain the long-term increase in temperatures. The relationships are mostly at the interannual rather than the decadal and longer timescales. The decadal temperature rise, therefore, reflects a general warming of the Southern Ocean, rather than decadal-scale variations in the circulation.
format Article in Journal/Newspaper
author Jones, PD
Salinger, MJ
Mullan, AB
spellingShingle Jones, PD
Salinger, MJ
Mullan, AB
Extratropical circulation indices in the Southern Hemisphere based on station data
author_facet Jones, PD
Salinger, MJ
Mullan, AB
author_sort Jones, PD
title Extratropical circulation indices in the Southern Hemisphere based on station data
title_short Extratropical circulation indices in the Southern Hemisphere based on station data
title_full Extratropical circulation indices in the Southern Hemisphere based on station data
title_fullStr Extratropical circulation indices in the Southern Hemisphere based on station data
title_full_unstemmed Extratropical circulation indices in the Southern Hemisphere based on station data
title_sort extratropical circulation indices in the southern hemisphere based on station data
publishDate 1999
url https://ueaeprints.uea.ac.uk/id/eprint/33988/
https://doi.org/10.1002/(SICI)1097-0088(199910)19:12<1301::AID-JOC425>3.0.CO;2-P
geographic Austral
New Zealand
Southern Ocean
geographic_facet Austral
New Zealand
Southern Ocean
genre Southern Ocean
genre_facet Southern Ocean
op_relation Jones, PD, Salinger, MJ and Mullan, AB (1999) Extratropical circulation indices in the Southern Hemisphere based on station data. International Journal of Climatology, 19 (12). pp. 1301-1317. ISSN 0899-8418
doi:10.1002/(SICI)1097-0088(199910)19:12<1301::AID-JOC425>3.0.CO;2-P
op_doi https://doi.org/10.1002/(SICI)1097-0088(199910)19:12<1301::AID-JOC425>3.0.CO;2-P
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