Stratospheric downward wave reflection events modulate North American weather regimes and cold spells
<p>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...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2022-11-01
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| Series: | Weather and Climate Dynamics |
| Online Access: | https://wcd.copernicus.org/articles/3/1215/2022/wcd-3-1215-2022.pdf |
| _version_ | 1811334281879879680 |
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| author | G. Messori G. Messori G. Messori G. Messori M. Kretschmer S. H. Lee V. Wendt V. Wendt |
| author_facet | G. Messori G. Messori G. Messori G. Messori M. Kretschmer S. H. Lee V. Wendt V. Wendt |
| author_sort | G. Messori |
| collection | DOAJ |
| description | <p>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 <i>reflection events</i>. 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.</p> |
| first_indexed | 2024-04-13T17:06:28Z |
| format | Article |
| id | doaj.art-c1b800df94e84ed6a2d827e9fccadfe6 |
| institution | Directory Open Access Journal |
| issn | 2698-4016 |
| language | English |
| last_indexed | 2024-04-13T17:06:28Z |
| publishDate | 2022-11-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Weather and Climate Dynamics |
| spelling | doaj.art-c1b800df94e84ed6a2d827e9fccadfe62022-12-22T02:38:28ZengCopernicus PublicationsWeather and Climate Dynamics2698-40162022-11-0131215123610.5194/wcd-3-1215-2022Stratospheric downward wave reflection events modulate North American weather regimes and cold spellsG. Messori0G. Messori1G. Messori2G. Messori3M. Kretschmer4S. H. Lee5V. Wendt6V. Wendt7Department of Earth Sciences, Uppsala University, Uppsala, SwedenCentre of Natural Hazards and Disaster Science (CNDS), Uppsala, SwedenDepartment of Meteorology, Stockholm University, Stockholm, SwedenBolin Centre for Climate Research, Stockholm, SwedenDepartment of Meteorology, University of Reading, Reading, UKDepartment of Applied Physics and Applied Mathematics, Columbia University, New York, NY, USAInstitute for Solar-Terrestrial Physics, German Aerospace Center (DLR), Neustrelitz, Germanypreviously published under the name Vivien Matthias<p>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 <i>reflection events</i>. 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.</p>https://wcd.copernicus.org/articles/3/1215/2022/wcd-3-1215-2022.pdf |
| spellingShingle | G. Messori G. Messori G. Messori G. Messori M. Kretschmer S. H. Lee V. Wendt V. Wendt Stratospheric downward wave reflection events modulate North American weather regimes and cold spells Weather and Climate Dynamics |
| title | 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_short | 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 |
| url | https://wcd.copernicus.org/articles/3/1215/2022/wcd-3-1215-2022.pdf |
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