Predictability of the 2020 Antarctic strong vortex event and the role of ozone forcing
In the austral spring seasons of 2020-2022, the Antarctic stratosphere experienced three consecutive strong vortex events. In particular, the Antarctic vortex of October-December 2020 was the strongest on record in the satellite era for that season at 60°S in the mid- to lower stratosphere. However,...
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crwinnower:10.22541/au.170869776.61634034/v1 2024-06-02T07:58:13+00:00 Predictability of the 2020 Antarctic strong vortex event and the role of ozone forcing Lim, Eun-Pa Zhou, Linjing Young, Griffith A Santra, Abhik Rudeva, Irina Hope, Pandora Wheeler, Matthew Comstock Arblaster, Julie M. Hendon, Harry H. Manney, Gloria L Son, Seok-Woo Oh, Jiyoung 2024 http://dx.doi.org/10.22541/au.170869776.61634034/v1 unknown Authorea, Inc. posted-content 2024 crwinnower https://doi.org/10.22541/au.170869776.61634034/v1 2024-05-07T14:19:26Z In the austral spring seasons of 2020-2022, the Antarctic stratosphere experienced three consecutive strong vortex events. In particular, the Antarctic vortex of October-December 2020 was the strongest on record in the satellite era for that season at 60°S in the mid- to lower stratosphere. However, it was poorly predicted by the Australian Bureau of Meteorology’s operational seasonal climate forecast system of that time, ACCESS-S1, even at a short lead time of a month. Using the current operational forecast system, ACCESS-S2, we have, therefore, tried to find a primary cause of the limited predictability of this event and conducted forecast sensitivity experiments to climatological versus observation-based ozone to understand the potential role of the ozone forcing in the strong vortex event and associated anomalies of the Southern Annular Mode (SAM) and south-eastern Australian rainfall. Here, we show that the 2020 strong vortex event did not follow the canonical dynamical evolution seen in previous strong vortex events in spring, whereas the ACCESS-S2 control forecasts with the climatological ozone did, which likely accounts for the inaccurate forecasts of ACCESS-S1/S2 at 1-month lead time. Forcing ACCESS-S2 with observed ozone significantly improved the skill in predicting the strong vortex in October-December 2020 and the subsequent positive SAM and related rainfall increase over south-eastern Australia in the summer of December 2020 to February 2021. These results highlight an important role of ozone variations in seasonal climate forecasting as a source of long-lead predictability, and therefore, a need for improved ozone forcing in future ACCESS-S development. Other/Unknown Material Antarc* Antarctic The Winnower Antarctic Austral The Antarctic |
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In the austral spring seasons of 2020-2022, the Antarctic stratosphere experienced three consecutive strong vortex events. In particular, the Antarctic vortex of October-December 2020 was the strongest on record in the satellite era for that season at 60°S in the mid- to lower stratosphere. However, it was poorly predicted by the Australian Bureau of Meteorology’s operational seasonal climate forecast system of that time, ACCESS-S1, even at a short lead time of a month. Using the current operational forecast system, ACCESS-S2, we have, therefore, tried to find a primary cause of the limited predictability of this event and conducted forecast sensitivity experiments to climatological versus observation-based ozone to understand the potential role of the ozone forcing in the strong vortex event and associated anomalies of the Southern Annular Mode (SAM) and south-eastern Australian rainfall. Here, we show that the 2020 strong vortex event did not follow the canonical dynamical evolution seen in previous strong vortex events in spring, whereas the ACCESS-S2 control forecasts with the climatological ozone did, which likely accounts for the inaccurate forecasts of ACCESS-S1/S2 at 1-month lead time. Forcing ACCESS-S2 with observed ozone significantly improved the skill in predicting the strong vortex in October-December 2020 and the subsequent positive SAM and related rainfall increase over south-eastern Australia in the summer of December 2020 to February 2021. These results highlight an important role of ozone variations in seasonal climate forecasting as a source of long-lead predictability, and therefore, a need for improved ozone forcing in future ACCESS-S development. |
format |
Other/Unknown Material |
author |
Lim, Eun-Pa Zhou, Linjing Young, Griffith A Santra, Abhik Rudeva, Irina Hope, Pandora Wheeler, Matthew Comstock Arblaster, Julie M. Hendon, Harry H. Manney, Gloria L Son, Seok-Woo Oh, Jiyoung |
spellingShingle |
Lim, Eun-Pa Zhou, Linjing Young, Griffith A Santra, Abhik Rudeva, Irina Hope, Pandora Wheeler, Matthew Comstock Arblaster, Julie M. Hendon, Harry H. Manney, Gloria L Son, Seok-Woo Oh, Jiyoung Predictability of the 2020 Antarctic strong vortex event and the role of ozone forcing |
author_facet |
Lim, Eun-Pa Zhou, Linjing Young, Griffith A Santra, Abhik Rudeva, Irina Hope, Pandora Wheeler, Matthew Comstock Arblaster, Julie M. Hendon, Harry H. Manney, Gloria L Son, Seok-Woo Oh, Jiyoung |
author_sort |
Lim, Eun-Pa |
title |
Predictability of the 2020 Antarctic strong vortex event and the role of ozone forcing |
title_short |
Predictability of the 2020 Antarctic strong vortex event and the role of ozone forcing |
title_full |
Predictability of the 2020 Antarctic strong vortex event and the role of ozone forcing |
title_fullStr |
Predictability of the 2020 Antarctic strong vortex event and the role of ozone forcing |
title_full_unstemmed |
Predictability of the 2020 Antarctic strong vortex event and the role of ozone forcing |
title_sort |
predictability of the 2020 antarctic strong vortex event and the role of ozone forcing |
publisher |
Authorea, Inc. |
publishDate |
2024 |
url |
http://dx.doi.org/10.22541/au.170869776.61634034/v1 |
geographic |
Antarctic Austral The Antarctic |
geographic_facet |
Antarctic Austral The Antarctic |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_doi |
https://doi.org/10.22541/au.170869776.61634034/v1 |
_version_ |
1800741497829588992 |