Tropical and subtropical forcing of future southern hemisphere stationary wave changes
Stationary wave changes play a significant role in the regional climate change response in Southern Hemisphere (SH) winter. In particular, almost all CMIP5 models feature a substantial strengthening of the westerlies to the south of Australia and enhancement of the subtropical jet over the eastern P...
Main Authors: | , , |
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Format: | Journal article |
Language: | English |
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American Meteorological Society
2021
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_version_ | 1797058693063245824 |
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author | Patterson, M Woollings, T Bracegirdle, TJ |
author_facet | Patterson, M Woollings, T Bracegirdle, TJ |
author_sort | Patterson, M |
collection | OXFORD |
description | Stationary wave changes play a significant role in the regional climate change response in Southern Hemisphere (SH) winter. In particular, almost all CMIP5 models feature a substantial strengthening of the westerlies to the south of Australia and enhancement of the subtropical jet over the eastern Pacific in winter. In this study we investigate the mechanisms behind these changes, finding that the stationary wave response can largely be explained via reductions in the magnitude of the upper level Rossby wave source over the tropical / subtropical East Pacific. The Rossby wave source changes in this region are robust across the model ensemble and are strongly correlated with changes to low latitude circulation patterns, in particular, the projected southward migration of the Hadley cell and weakening of the Walker circulation. To confirm our mechanism of future changes, we employ a series of barotropic model experiments in which the barotropic model is given a background state identical to a particular CMIP5 model and an anomalous Rossby wave source is imposed. This simple approach is able to capture the primary features of the ensemble mean change, including the cyclonic anomaly south of Australia, and is also able to capture many of the inter-model differences. These findings will help to advance our understanding of the mechanisms underpinning SH extratropical circulation changes under climate change.
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first_indexed | 2024-03-06T19:53:53Z |
format | Journal article |
id | oxford-uuid:24e11ea2-8929-4830-b650-684e7f33c4a7 |
institution | University of Oxford |
language | English |
last_indexed | 2024-03-06T19:53:53Z |
publishDate | 2021 |
publisher | American Meteorological Society |
record_format | dspace |
spelling | oxford-uuid:24e11ea2-8929-4830-b650-684e7f33c4a72022-03-26T11:52:40ZTropical and subtropical forcing of future southern hemisphere stationary wave changesJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:24e11ea2-8929-4830-b650-684e7f33c4a7EnglishSymplectic ElementsAmerican Meteorological Society2021Patterson, MWoollings, TBracegirdle, TJStationary wave changes play a significant role in the regional climate change response in Southern Hemisphere (SH) winter. In particular, almost all CMIP5 models feature a substantial strengthening of the westerlies to the south of Australia and enhancement of the subtropical jet over the eastern Pacific in winter. In this study we investigate the mechanisms behind these changes, finding that the stationary wave response can largely be explained via reductions in the magnitude of the upper level Rossby wave source over the tropical / subtropical East Pacific. The Rossby wave source changes in this region are robust across the model ensemble and are strongly correlated with changes to low latitude circulation patterns, in particular, the projected southward migration of the Hadley cell and weakening of the Walker circulation. To confirm our mechanism of future changes, we employ a series of barotropic model experiments in which the barotropic model is given a background state identical to a particular CMIP5 model and an anomalous Rossby wave source is imposed. This simple approach is able to capture the primary features of the ensemble mean change, including the cyclonic anomaly south of Australia, and is also able to capture many of the inter-model differences. These findings will help to advance our understanding of the mechanisms underpinning SH extratropical circulation changes under climate change. |
spellingShingle | Patterson, M Woollings, T Bracegirdle, TJ Tropical and subtropical forcing of future southern hemisphere stationary wave changes |
title | Tropical and subtropical forcing of future southern hemisphere stationary wave changes |
title_full | Tropical and subtropical forcing of future southern hemisphere stationary wave changes |
title_fullStr | Tropical and subtropical forcing of future southern hemisphere stationary wave changes |
title_full_unstemmed | Tropical and subtropical forcing of future southern hemisphere stationary wave changes |
title_short | Tropical and subtropical forcing of future southern hemisphere stationary wave changes |
title_sort | tropical and subtropical forcing of future southern hemisphere stationary wave changes |
work_keys_str_mv | AT pattersonm tropicalandsubtropicalforcingoffuturesouthernhemispherestationarywavechanges AT woollingst tropicalandsubtropicalforcingoffuturesouthernhemispherestationarywavechanges AT bracegirdletj tropicalandsubtropicalforcingoffuturesouthernhemispherestationarywavechanges |