The different stratospheric influence on cold-extremes in Eurasia and North America
The stratospheric polar vortex can influence the tropospheric circulation and thereby winter weather in the mid-latitudes. Weak vortex states, often associated with sudden stratospheric warmings (SSW), have been shown to increase the risk of cold-spells especially over Eurasia, but its role for Nort...
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ftpotsdamik:oai:publications.pik-potsdam.de:item_22710 2023-10-29T02:38:32+01:00 The different stratospheric influence on cold-extremes in Eurasia and North America Kretschmer, M. Cohen, J. Matthias, V. Runge, J. Coumou, D. 2018 application/pdf https://publications.pik-potsdam.de/pubman/item/item_22710 https://publications.pik-potsdam.de/pubman/item/item_22710_1/component/file_22711/Revised_manuscript_revision_round4_nofigures.pdf https://publications.pik-potsdam.de/pubman/item/item_22710_1/component/file_22712/8246oa.pdf unknown info:eu-repo/semantics/altIdentifier/doi/10.1038/s41612-018-0054-4 https://publications.pik-potsdam.de/pubman/item/item_22710 https://publications.pik-potsdam.de/pubman/item/item_22710_1/component/file_22711/Revised_manuscript_revision_round4_nofigures.pdf https://publications.pik-potsdam.de/pubman/item/item_22710_1/component/file_22712/8246oa.pdf info:eu-repo/semantics/openAccess npj Climate and Atmospheric Science info:eu-repo/semantics/article 2018 ftpotsdamik https://doi.org/10.1038/s41612-018-0054-4 2023-09-30T17:59:59Z The stratospheric polar vortex can influence the tropospheric circulation and thereby winter weather in the mid-latitudes. Weak vortex states, often associated with sudden stratospheric warmings (SSW), have been shown to increase the risk of cold-spells especially over Eurasia, but its role for North American winters is less clear. Using cluster analysis, we show that there are two dominant patterns of increased polar cap heights in the lower stratosphere. Both patterns represent a weak polar vortex but they are associated with different wave mechanisms and different regional tropospheric impacts. The first pattern is zonally symmetric and associated with absorbed upward-propagating wave activity, leading to a negative phase of the North Atlantic Oscillation (NAO) and cold-air outbreaks over northern Eurasia. This coupling mechanism is well-documented in the literature and is consistent with the downward migration of the northern annular mode (NAM). The second pattern is zonally asymmetric and linked to downward reflected planetary waves over Canada followed by a negative phase of the Western Pacific Oscillation (WPO) and cold-spells in Central Canada and the Great Lakes region. Causal effect network (CEN) analyses confirm the atmospheric pathways associated with this asymmetric pattern. Moreover, our findings suggest the reflective mechanism to be sensitive to the exact region of upward wave-activity fluxes and to be state-dependent on the strength of the vortex. Identifying the causal pathways that operate on weekly to monthly timescales can pave the way for improved sub-seasonal to seasonal forecasting of cold spells in the mid-latitudes. Article in Journal/Newspaper North Atlantic North Atlantic oscillation Publication Database PIK (Potsdam Institute for Climate Impact Research) npj Climate and Atmospheric Science 1 1 |
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Open Polar |
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Publication Database PIK (Potsdam Institute for Climate Impact Research) |
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ftpotsdamik |
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description |
The stratospheric polar vortex can influence the tropospheric circulation and thereby winter weather in the mid-latitudes. Weak vortex states, often associated with sudden stratospheric warmings (SSW), have been shown to increase the risk of cold-spells especially over Eurasia, but its role for North American winters is less clear. Using cluster analysis, we show that there are two dominant patterns of increased polar cap heights in the lower stratosphere. Both patterns represent a weak polar vortex but they are associated with different wave mechanisms and different regional tropospheric impacts. The first pattern is zonally symmetric and associated with absorbed upward-propagating wave activity, leading to a negative phase of the North Atlantic Oscillation (NAO) and cold-air outbreaks over northern Eurasia. This coupling mechanism is well-documented in the literature and is consistent with the downward migration of the northern annular mode (NAM). The second pattern is zonally asymmetric and linked to downward reflected planetary waves over Canada followed by a negative phase of the Western Pacific Oscillation (WPO) and cold-spells in Central Canada and the Great Lakes region. Causal effect network (CEN) analyses confirm the atmospheric pathways associated with this asymmetric pattern. Moreover, our findings suggest the reflective mechanism to be sensitive to the exact region of upward wave-activity fluxes and to be state-dependent on the strength of the vortex. Identifying the causal pathways that operate on weekly to monthly timescales can pave the way for improved sub-seasonal to seasonal forecasting of cold spells in the mid-latitudes. |
format |
Article in Journal/Newspaper |
author |
Kretschmer, M. Cohen, J. Matthias, V. Runge, J. Coumou, D. |
spellingShingle |
Kretschmer, M. Cohen, J. Matthias, V. Runge, J. Coumou, D. The different stratospheric influence on cold-extremes in Eurasia and North America |
author_facet |
Kretschmer, M. Cohen, J. Matthias, V. Runge, J. Coumou, D. |
author_sort |
Kretschmer, M. |
title |
The different stratospheric influence on cold-extremes in Eurasia and North America |
title_short |
The different stratospheric influence on cold-extremes in Eurasia and North America |
title_full |
The different stratospheric influence on cold-extremes in Eurasia and North America |
title_fullStr |
The different stratospheric influence on cold-extremes in Eurasia and North America |
title_full_unstemmed |
The different stratospheric influence on cold-extremes in Eurasia and North America |
title_sort |
different stratospheric influence on cold-extremes in eurasia and north america |
publishDate |
2018 |
url |
https://publications.pik-potsdam.de/pubman/item/item_22710 https://publications.pik-potsdam.de/pubman/item/item_22710_1/component/file_22711/Revised_manuscript_revision_round4_nofigures.pdf https://publications.pik-potsdam.de/pubman/item/item_22710_1/component/file_22712/8246oa.pdf |
genre |
North Atlantic North Atlantic oscillation |
genre_facet |
North Atlantic North Atlantic oscillation |
op_source |
npj Climate and Atmospheric Science |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1038/s41612-018-0054-4 https://publications.pik-potsdam.de/pubman/item/item_22710 https://publications.pik-potsdam.de/pubman/item/item_22710_1/component/file_22711/Revised_manuscript_revision_round4_nofigures.pdf https://publications.pik-potsdam.de/pubman/item/item_22710_1/component/file_22712/8246oa.pdf |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1038/s41612-018-0054-4 |
container_title |
npj Climate and Atmospheric Science |
container_volume |
1 |
container_issue |
1 |
_version_ |
1781064668882665472 |