Stratospheric wave driving events as an alternative to sudden stratospheric warmings
Natural variations in the strength of the northern stratospheric polar vortex, so-called polar vortex events, help to improve subseasonal-to-seasonal (S2S) predictions of winter climate. Past research on polar vortex events has been largely focused on sudden stratospheric warming events (SSWs), a cl...
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ftcopernicus:oai:publications.copernicus.org:wcd101713 2023-05-15T15:09:00+02:00 Stratospheric wave driving events as an alternative to sudden stratospheric warmings Reichler, Thomas Jucker, Martin 2022-06-17 application/pdf https://doi.org/10.5194/wcd-3-659-2022 https://wcd.copernicus.org/articles/3/659/2022/ eng eng doi:10.5194/wcd-3-659-2022 https://wcd.copernicus.org/articles/3/659/2022/ eISSN: 2698-4016 Text 2022 ftcopernicus https://doi.org/10.5194/wcd-3-659-2022 2022-06-20T16:22:42Z Natural variations in the strength of the northern stratospheric polar vortex, so-called polar vortex events, help to improve subseasonal-to-seasonal (S2S) predictions of winter climate. Past research on polar vortex events has been largely focused on sudden stratospheric warming events (SSWs), a class of relatively strong weakenings of the polar vortex. Commonly, SSWs are defined when the polar vortex reverses its climatological wintertime westerly wind direction. In this study, however, we use an alternative definition, based on the weighted time-integrated upward wave activity flux at the lower stratosphere. We use a long control simulation with a stratosphere-resolving model and the ERA5 reanalysis to compare various aspects of the wave activity definition with common SSWs over the Arctic. About half of the wave events are identical to common SSWs. However, there exist several advantages for defining stratospheric weak extremes based on wave events rather than using the common SSW definition: the wave activity flux definition captures with one criterion a variety of different event types, detects strong SSWs and strong final warming events, avoids weak SSWs that have little surface impact, and potentially lengthens the prediction horizon of the surface response. We therefore conclude that the wave driving represents a useful early indicator for stratospheric polar vortex events, which exploits the stratospheric potential for creating predictable surface signals better than common SSWs. Text Arctic Copernicus Publications: E-Journals Arctic Weather and Climate Dynamics 3 2 659 677 |
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Copernicus Publications: E-Journals |
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English |
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Natural variations in the strength of the northern stratospheric polar vortex, so-called polar vortex events, help to improve subseasonal-to-seasonal (S2S) predictions of winter climate. Past research on polar vortex events has been largely focused on sudden stratospheric warming events (SSWs), a class of relatively strong weakenings of the polar vortex. Commonly, SSWs are defined when the polar vortex reverses its climatological wintertime westerly wind direction. In this study, however, we use an alternative definition, based on the weighted time-integrated upward wave activity flux at the lower stratosphere. We use a long control simulation with a stratosphere-resolving model and the ERA5 reanalysis to compare various aspects of the wave activity definition with common SSWs over the Arctic. About half of the wave events are identical to common SSWs. However, there exist several advantages for defining stratospheric weak extremes based on wave events rather than using the common SSW definition: the wave activity flux definition captures with one criterion a variety of different event types, detects strong SSWs and strong final warming events, avoids weak SSWs that have little surface impact, and potentially lengthens the prediction horizon of the surface response. We therefore conclude that the wave driving represents a useful early indicator for stratospheric polar vortex events, which exploits the stratospheric potential for creating predictable surface signals better than common SSWs. |
format |
Text |
author |
Reichler, Thomas Jucker, Martin |
spellingShingle |
Reichler, Thomas Jucker, Martin Stratospheric wave driving events as an alternative to sudden stratospheric warmings |
author_facet |
Reichler, Thomas Jucker, Martin |
author_sort |
Reichler, Thomas |
title |
Stratospheric wave driving events as an alternative to sudden stratospheric warmings |
title_short |
Stratospheric wave driving events as an alternative to sudden stratospheric warmings |
title_full |
Stratospheric wave driving events as an alternative to sudden stratospheric warmings |
title_fullStr |
Stratospheric wave driving events as an alternative to sudden stratospheric warmings |
title_full_unstemmed |
Stratospheric wave driving events as an alternative to sudden stratospheric warmings |
title_sort |
stratospheric wave driving events as an alternative to sudden stratospheric warmings |
publishDate |
2022 |
url |
https://doi.org/10.5194/wcd-3-659-2022 https://wcd.copernicus.org/articles/3/659/2022/ |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic |
genre_facet |
Arctic |
op_source |
eISSN: 2698-4016 |
op_relation |
doi:10.5194/wcd-3-659-2022 https://wcd.copernicus.org/articles/3/659/2022/ |
op_doi |
https://doi.org/10.5194/wcd-3-659-2022 |
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Weather and Climate Dynamics |
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3 |
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2 |
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659 |
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677 |
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1766340248959188992 |