Influence of subtropical Rossby wave trains on planetary wave activity over Antarctica in September 2002
At the beginning of September 2002, strong convection processes over south-eastern Indonesia and over south-eastern Africa have been observed. Due to the strong upper tropospheric divergent outflow, two Rossby wave trains (RWTs) were generated. Their south-eastward propagation was controlled by the...
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ftdoajarticles:oai:doaj.org/article:f36938d848e24d7ba98eed24ad675185 2023-05-15T14:00:16+02:00 Influence of subtropical Rossby wave trains on planetary wave activity over Antarctica in September 2002 Dieter H. W. Peters Pavel Vargin 2015-05-01T00:00:00Z https://doi.org/10.3402/tellusa.v67.25875 https://doaj.org/article/f36938d848e24d7ba98eed24ad675185 EN eng Stockholm University Press http://www.tellusa.net/index.php/tellusa/article/view/25875/pdf_36 https://doaj.org/toc/1600-0870 1600-0870 doi:10.3402/tellusa.v67.25875 https://doaj.org/article/f36938d848e24d7ba98eed24ad675185 Tellus: Series A, Dynamic Meteorology and Oceanography, Vol 67, Iss 0, Pp 1-13 (2015) dynamic meteorology Rossby wave train planetary waves Oceanography GC1-1581 Meteorology. Climatology QC851-999 article 2015 ftdoajarticles https://doi.org/10.3402/tellusa.v67.25875 2022-12-30T23:58:24Z At the beginning of September 2002, strong convection processes over south-eastern Indonesia and over south-eastern Africa have been observed. Due to the strong upper tropospheric divergent outflow, two Rossby wave trains (RWTs) were generated. Their south-eastward propagation was controlled by the mean background flow. These two wave trains are visible in observations. It is hypothesised that these wave trains cause enhanced planetary wave activity fluxes which are a result of an amplified planetary wave 2 in the upper troposphere/lower stratosphere over Antarctica. Such a change of the planetary wave structure was diagnosed in September 2002, prior to the first observed major sudden stratospheric warming event on the Southern Hemisphere. A simplified version of GCM ECHAM4 is used to evaluate the hypothesis. Sensitivity experiments were performed for a mean background flow similar to September 2002. Furthermore, the wave maker approach was used to generate Rossby waves in the subtropical upper troposphere at two distinct locations which are corresponding to the observed regions of divergent outflow. As a main result, after about 2 weeks of model integration with wave maker forcing, we find two RWTs with a south-eastward propagation inducing a polar amplification of planetary wave 2 in the upper troposphere and lower/middle stratosphere. The poleward wave activity flux is enhanced in comparison to the control run without any wave maker forcing. The convergence of the Eliassen–Palm flux causes a 25% deceleration of zonal mean zonal wind in the model stratosphere but no wind reversal. Sensitivity runs support the robustness of these results. The obtained model results highlight the mechanism and confirm the hypothesis that enhanced planetary wave activity in austral polar region in 2002 is caused by enhanced subtropical forcing of two RWTs. Article in Journal/Newspaper Antarc* Antarctica Directory of Open Access Journals: DOAJ Articles Austral Tellus A: Dynamic Meteorology and Oceanography 67 1 25875 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
dynamic meteorology Rossby wave train planetary waves Oceanography GC1-1581 Meteorology. Climatology QC851-999 |
spellingShingle |
dynamic meteorology Rossby wave train planetary waves Oceanography GC1-1581 Meteorology. Climatology QC851-999 Dieter H. W. Peters Pavel Vargin Influence of subtropical Rossby wave trains on planetary wave activity over Antarctica in September 2002 |
topic_facet |
dynamic meteorology Rossby wave train planetary waves Oceanography GC1-1581 Meteorology. Climatology QC851-999 |
description |
At the beginning of September 2002, strong convection processes over south-eastern Indonesia and over south-eastern Africa have been observed. Due to the strong upper tropospheric divergent outflow, two Rossby wave trains (RWTs) were generated. Their south-eastward propagation was controlled by the mean background flow. These two wave trains are visible in observations. It is hypothesised that these wave trains cause enhanced planetary wave activity fluxes which are a result of an amplified planetary wave 2 in the upper troposphere/lower stratosphere over Antarctica. Such a change of the planetary wave structure was diagnosed in September 2002, prior to the first observed major sudden stratospheric warming event on the Southern Hemisphere. A simplified version of GCM ECHAM4 is used to evaluate the hypothesis. Sensitivity experiments were performed for a mean background flow similar to September 2002. Furthermore, the wave maker approach was used to generate Rossby waves in the subtropical upper troposphere at two distinct locations which are corresponding to the observed regions of divergent outflow. As a main result, after about 2 weeks of model integration with wave maker forcing, we find two RWTs with a south-eastward propagation inducing a polar amplification of planetary wave 2 in the upper troposphere and lower/middle stratosphere. The poleward wave activity flux is enhanced in comparison to the control run without any wave maker forcing. The convergence of the Eliassen–Palm flux causes a 25% deceleration of zonal mean zonal wind in the model stratosphere but no wind reversal. Sensitivity runs support the robustness of these results. The obtained model results highlight the mechanism and confirm the hypothesis that enhanced planetary wave activity in austral polar region in 2002 is caused by enhanced subtropical forcing of two RWTs. |
format |
Article in Journal/Newspaper |
author |
Dieter H. W. Peters Pavel Vargin |
author_facet |
Dieter H. W. Peters Pavel Vargin |
author_sort |
Dieter H. W. Peters |
title |
Influence of subtropical Rossby wave trains on planetary wave activity over Antarctica in September 2002 |
title_short |
Influence of subtropical Rossby wave trains on planetary wave activity over Antarctica in September 2002 |
title_full |
Influence of subtropical Rossby wave trains on planetary wave activity over Antarctica in September 2002 |
title_fullStr |
Influence of subtropical Rossby wave trains on planetary wave activity over Antarctica in September 2002 |
title_full_unstemmed |
Influence of subtropical Rossby wave trains on planetary wave activity over Antarctica in September 2002 |
title_sort |
influence of subtropical rossby wave trains on planetary wave activity over antarctica in september 2002 |
publisher |
Stockholm University Press |
publishDate |
2015 |
url |
https://doi.org/10.3402/tellusa.v67.25875 https://doaj.org/article/f36938d848e24d7ba98eed24ad675185 |
geographic |
Austral |
geographic_facet |
Austral |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_source |
Tellus: Series A, Dynamic Meteorology and Oceanography, Vol 67, Iss 0, Pp 1-13 (2015) |
op_relation |
http://www.tellusa.net/index.php/tellusa/article/view/25875/pdf_36 https://doaj.org/toc/1600-0870 1600-0870 doi:10.3402/tellusa.v67.25875 https://doaj.org/article/f36938d848e24d7ba98eed24ad675185 |
op_doi |
https://doi.org/10.3402/tellusa.v67.25875 |
container_title |
Tellus A: Dynamic Meteorology and Oceanography |
container_volume |
67 |
container_issue |
1 |
container_start_page |
25875 |
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1766269305293373440 |