On the Seasonality of the El Niño Teleconnection to the Amundsen Sea Region
The Amundsen Sea low (ASL) is a quasi–stationary low pressure system that affects climate in West Antarctica. Previous studies have shown that the El Niño Southern Oscillation modulates the position and strength of the ASL with the strongest teleconnection found in austral winter despite the amplitu...
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ftleedsuniv:oai:eprints.whiterose.ac.uk:145354 2023-05-15T13:23:45+02:00 On the Seasonality of the El Niño Teleconnection to the Amundsen Sea Region Yiu, YYS Maycock, AC 2019-08-01 text https://eprints.whiterose.ac.uk/145354/ https://eprints.whiterose.ac.uk/145354/14/jcli-d-18-0813.1.pdf en eng American Meteorological Society https://eprints.whiterose.ac.uk/145354/14/jcli-d-18-0813.1.pdf Yiu, YYS and Maycock, AC orcid.org/0000-0002-6614-1127 (2019) On the Seasonality of the El Niño Teleconnection to the Amundsen Sea Region. Journal of Climate, 32 (15). pp. 4829-4845. ISSN 0894-8755 Article NonPeerReviewed 2019 ftleedsuniv 2023-01-30T22:18:17Z The Amundsen Sea low (ASL) is a quasi–stationary low pressure system that affects climate in West Antarctica. Previous studies have shown that the El Niño Southern Oscillation modulates the position and strength of the ASL with the strongest teleconnection found in austral winter despite the amplitude of ENSO events generally being largest in austral autumn/summer. This study investigates the mechanisms behind the seasonality of the El Niño teleconnection to the Amundsen Sea region (ASR) using experiments with the HadGEM3 climate model forced with an idealised fixed El Niño sea surface temperature anomaly present throughout the year. The seasonality of the El Niño–ASR teleconnection is found to originate from seasonal differences in the large-scale zonal winds in the south Pacific sector. In austral winter, the region of strong absolute vorticity near ∼30◦S provided by the subtropical jet, in combination with the changes to upper tropospheric divergence due to the El Niño perturbation, acts as an anomalous Rossby wave source that is largely absent in austral summer. Furthermore, in austral summer the poleward propagation of tropically-sourced Rossby waves into the ASR is inhibited by the strong polar front jet in the south Pacific sector, which leads to Rossby wave reflection away from the ASR. In austral winter, Rossby waves are able to propagate into the ASR forming part of the Pacific South America pattern. The lack of the Rossby wave source in the tropical Pacific and the absence of favourable conditions for wave propagation explains the weaker El Niño–ASR teleconnection in austral summer compared to austral winter. Article in Journal/Newspaper Amundsen Sea Antarc* Antarctica West Antarctica White Rose Research Online (Universities of Leeds, Sheffield & York) Austral West Antarctica Amundsen Sea Pacific |
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Open Polar |
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White Rose Research Online (Universities of Leeds, Sheffield & York) |
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ftleedsuniv |
language |
English |
description |
The Amundsen Sea low (ASL) is a quasi–stationary low pressure system that affects climate in West Antarctica. Previous studies have shown that the El Niño Southern Oscillation modulates the position and strength of the ASL with the strongest teleconnection found in austral winter despite the amplitude of ENSO events generally being largest in austral autumn/summer. This study investigates the mechanisms behind the seasonality of the El Niño teleconnection to the Amundsen Sea region (ASR) using experiments with the HadGEM3 climate model forced with an idealised fixed El Niño sea surface temperature anomaly present throughout the year. The seasonality of the El Niño–ASR teleconnection is found to originate from seasonal differences in the large-scale zonal winds in the south Pacific sector. In austral winter, the region of strong absolute vorticity near ∼30◦S provided by the subtropical jet, in combination with the changes to upper tropospheric divergence due to the El Niño perturbation, acts as an anomalous Rossby wave source that is largely absent in austral summer. Furthermore, in austral summer the poleward propagation of tropically-sourced Rossby waves into the ASR is inhibited by the strong polar front jet in the south Pacific sector, which leads to Rossby wave reflection away from the ASR. In austral winter, Rossby waves are able to propagate into the ASR forming part of the Pacific South America pattern. The lack of the Rossby wave source in the tropical Pacific and the absence of favourable conditions for wave propagation explains the weaker El Niño–ASR teleconnection in austral summer compared to austral winter. |
format |
Article in Journal/Newspaper |
author |
Yiu, YYS Maycock, AC |
spellingShingle |
Yiu, YYS Maycock, AC On the Seasonality of the El Niño Teleconnection to the Amundsen Sea Region |
author_facet |
Yiu, YYS Maycock, AC |
author_sort |
Yiu, YYS |
title |
On the Seasonality of the El Niño Teleconnection to the Amundsen Sea Region |
title_short |
On the Seasonality of the El Niño Teleconnection to the Amundsen Sea Region |
title_full |
On the Seasonality of the El Niño Teleconnection to the Amundsen Sea Region |
title_fullStr |
On the Seasonality of the El Niño Teleconnection to the Amundsen Sea Region |
title_full_unstemmed |
On the Seasonality of the El Niño Teleconnection to the Amundsen Sea Region |
title_sort |
on the seasonality of the el niño teleconnection to the amundsen sea region |
publisher |
American Meteorological Society |
publishDate |
2019 |
url |
https://eprints.whiterose.ac.uk/145354/ https://eprints.whiterose.ac.uk/145354/14/jcli-d-18-0813.1.pdf |
geographic |
Austral West Antarctica Amundsen Sea Pacific |
geographic_facet |
Austral West Antarctica Amundsen Sea Pacific |
genre |
Amundsen Sea Antarc* Antarctica West Antarctica |
genre_facet |
Amundsen Sea Antarc* Antarctica West Antarctica |
op_relation |
https://eprints.whiterose.ac.uk/145354/14/jcli-d-18-0813.1.pdf Yiu, YYS and Maycock, AC orcid.org/0000-0002-6614-1127 (2019) On the Seasonality of the El Niño Teleconnection to the Amundsen Sea Region. Journal of Climate, 32 (15). pp. 4829-4845. ISSN 0894-8755 |
_version_ |
1766374591707480064 |