Stratospheric downward wave reflection events modulate North American weather regimes and cold spells
The Arctic stratospheric polar vortex is an important driver of mid-latitude winter cold spells. One proposed coupling mechanism between the stratospheric polar vortex and the troposphere is upward-propagating planetary waves being reflected downward by the polar vortex. However, while the wave refl...
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2022
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Online Access: | https://doi.org/10.5194/wcd-3-1215-2022 https://doaj.org/article/c1b800df94e84ed6a2d827e9fccadfe6 |
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ftdoajarticles:oai:doaj.org/article:c1b800df94e84ed6a2d827e9fccadfe6 2023-05-15T15:07:16+02:00 Stratospheric downward wave reflection events modulate North American weather regimes and cold spells G. Messori M. Kretschmer S. H. Lee V. Wendt 2022-11-01T00:00:00Z https://doi.org/10.5194/wcd-3-1215-2022 https://doaj.org/article/c1b800df94e84ed6a2d827e9fccadfe6 EN eng Copernicus Publications https://wcd.copernicus.org/articles/3/1215/2022/wcd-3-1215-2022.pdf https://doaj.org/toc/2698-4016 doi:10.5194/wcd-3-1215-2022 2698-4016 https://doaj.org/article/c1b800df94e84ed6a2d827e9fccadfe6 Weather and Climate Dynamics, Vol 3, Pp 1215-1236 (2022) Meteorology. Climatology QC851-999 article 2022 ftdoajarticles https://doi.org/10.5194/wcd-3-1215-2022 2022-12-30T23:04:22Z The Arctic stratospheric polar vortex is an important driver of mid-latitude winter cold spells. One proposed coupling mechanism between the stratospheric polar vortex and the troposphere is upward-propagating planetary waves being reflected downward by the polar vortex. However, while the wave reflection mechanism is well-documented, its role in favouring cold spells is still under-explored. Here, we analyse such stratospheric wave reflections and their impact on the tropospheric circulation and surface temperatures over North America in winter. We present a physically interpretable regional stratospheric wave reflection detection metric and identify the tropospheric circulation anomalies associated with prolonged periods of wave reflection, which we term reflection events . In particular, we characterise the tropospheric anomalies through the lens of North American weather regimes. Stratospheric reflection events show a systematic evolution from a Pacific Trough regime – associated on average with positive temperature anomalies and a near-complete absence of anomalously cold temperatures in North America – to an Alaskan Ridge regime, which favours low temperatures over much of the continent. The most striking feature of the stratospheric reflection events is thus a rapid, continental-scale decrease in temperatures. These emerge as continental-scale cold spells by the end of the reflection events. Stratospheric reflection events are thus highly relevant in a tropospheric predictability perspective. Article in Journal/Newspaper Arctic Directory of Open Access Journals: DOAJ Articles Arctic Pacific Weather and Climate Dynamics 3 4 1215 1236 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Meteorology. Climatology QC851-999 |
spellingShingle |
Meteorology. Climatology QC851-999 G. Messori M. Kretschmer S. H. Lee V. Wendt Stratospheric downward wave reflection events modulate North American weather regimes and cold spells |
topic_facet |
Meteorology. Climatology QC851-999 |
description |
The Arctic stratospheric polar vortex is an important driver of mid-latitude winter cold spells. One proposed coupling mechanism between the stratospheric polar vortex and the troposphere is upward-propagating planetary waves being reflected downward by the polar vortex. However, while the wave reflection mechanism is well-documented, its role in favouring cold spells is still under-explored. Here, we analyse such stratospheric wave reflections and their impact on the tropospheric circulation and surface temperatures over North America in winter. We present a physically interpretable regional stratospheric wave reflection detection metric and identify the tropospheric circulation anomalies associated with prolonged periods of wave reflection, which we term reflection events . In particular, we characterise the tropospheric anomalies through the lens of North American weather regimes. Stratospheric reflection events show a systematic evolution from a Pacific Trough regime – associated on average with positive temperature anomalies and a near-complete absence of anomalously cold temperatures in North America – to an Alaskan Ridge regime, which favours low temperatures over much of the continent. The most striking feature of the stratospheric reflection events is thus a rapid, continental-scale decrease in temperatures. These emerge as continental-scale cold spells by the end of the reflection events. Stratospheric reflection events are thus highly relevant in a tropospheric predictability perspective. |
format |
Article in Journal/Newspaper |
author |
G. Messori M. Kretschmer S. H. Lee V. Wendt |
author_facet |
G. Messori M. Kretschmer S. H. Lee V. Wendt |
author_sort |
G. Messori |
title |
Stratospheric downward wave reflection events modulate North American weather regimes and cold spells |
title_short |
Stratospheric downward wave reflection events modulate North American weather regimes and cold spells |
title_full |
Stratospheric downward wave reflection events modulate North American weather regimes and cold spells |
title_fullStr |
Stratospheric downward wave reflection events modulate North American weather regimes and cold spells |
title_full_unstemmed |
Stratospheric downward wave reflection events modulate North American weather regimes and cold spells |
title_sort |
stratospheric downward wave reflection events modulate north american weather regimes and cold spells |
publisher |
Copernicus Publications |
publishDate |
2022 |
url |
https://doi.org/10.5194/wcd-3-1215-2022 https://doaj.org/article/c1b800df94e84ed6a2d827e9fccadfe6 |
geographic |
Arctic Pacific |
geographic_facet |
Arctic Pacific |
genre |
Arctic |
genre_facet |
Arctic |
op_source |
Weather and Climate Dynamics, Vol 3, Pp 1215-1236 (2022) |
op_relation |
https://wcd.copernicus.org/articles/3/1215/2022/wcd-3-1215-2022.pdf https://doaj.org/toc/2698-4016 doi:10.5194/wcd-3-1215-2022 2698-4016 https://doaj.org/article/c1b800df94e84ed6a2d827e9fccadfe6 |
op_doi |
https://doi.org/10.5194/wcd-3-1215-2022 |
container_title |
Weather and Climate Dynamics |
container_volume |
3 |
container_issue |
4 |
container_start_page |
1215 |
op_container_end_page |
1236 |
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1766338808068964352 |