The North Atlantic variability structure, storm tracks, and precipitation depending on the polar vortex strength
International audience There is ample evidence that the state of the northern polar stratospheric vortex in boreal winter influences tropospheric variability. Therefore, the main teleconnection patterns over the North Atlantic are defined separately for winter episodes in which the zonal mean wind a...
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ftccsdartic:oai:HAL:hal-00301446v1 2023-11-12T04:13:49+01:00 The North Atlantic variability structure, storm tracks, and precipitation depending on the polar vortex strength Walter, K. Graf, H.-F. Max Planck Institute for Meteorology (MPI-M) Max-Planck-Gesellschaft Centre for Atmospheric Science Cambridge, UK University of Cambridge UK (CAM) 2004-10-05 https://hal.science/hal-00301446 https://hal.science/hal-00301446/document https://hal.science/hal-00301446/file/acpd-4-6127-2004.pdf en eng HAL CCSD European Geosciences Union hal-00301446 https://hal.science/hal-00301446 https://hal.science/hal-00301446/document https://hal.science/hal-00301446/file/acpd-4-6127-2004.pdf info:eu-repo/semantics/OpenAccess ISSN: 1680-7367 EISSN: 1680-7375 Atmospheric Chemistry and Physics Discussions https://hal.science/hal-00301446 Atmospheric Chemistry and Physics Discussions, 2004, 4 (5), pp.6127-6148 [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere info:eu-repo/semantics/article Journal articles 2004 ftccsdartic 2023-10-21T23:13:25Z International audience There is ample evidence that the state of the northern polar stratospheric vortex in boreal winter influences tropospheric variability. Therefore, the main teleconnection patterns over the North Atlantic are defined separately for winter episodes in which the zonal mean wind at 50 hPa and 65° N is above or below the critical Rossby velocity for zonal planetary wave one. It turns out that the teleconnection structure in the middle and upper troposphere differs considerably between the two regimes of the polar vortex, while this is not the case at sea level. If the "polar vortex is strong", there exists "one" meridional dipole structure of geopotential height in the upper and middle troposphere, which is situated in the central North Atlantic. If the "polar vortex is weak", there exist "two" such dipoles, one over the western and one over the eastern North Atlantic. Storm tracks (and precipitation related with these) are determined by mid and upper tropospheric conditions and we find significant differences of these parameters between the stratospheric regimes. For the strong polar vortex regime, in case of a negative upper tropospheric "NAO" index we find a blocking height situation over the Northeast Atlantic and the strongest storm track of all. It is reaching far north into the Arctic Ocean and has a secondary maximum over the Denmark Strait. Such storm track is not found in composites based on a classic NAO defined by surface pressure differences between the Icelandic Low and the Azores High. Our results show that it is essential to include the state of the upper dynamic boundary conditions (the polar vortex strength) in any study of the variability over the North Atlantic. Climate forecast based solely on the forecast of a "classic NAO" and further statistical downscaling may lead to the wrong conclusions if the state of the polar vortex is not considered as well. Article in Journal/Newspaper Arctic Arctic Ocean Denmark Strait North Atlantic Northeast Atlantic Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Arctic Arctic Ocean |
institution |
Open Polar |
collection |
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
op_collection_id |
ftccsdartic |
language |
English |
topic |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
spellingShingle |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere Walter, K. Graf, H.-F. The North Atlantic variability structure, storm tracks, and precipitation depending on the polar vortex strength |
topic_facet |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
description |
International audience There is ample evidence that the state of the northern polar stratospheric vortex in boreal winter influences tropospheric variability. Therefore, the main teleconnection patterns over the North Atlantic are defined separately for winter episodes in which the zonal mean wind at 50 hPa and 65° N is above or below the critical Rossby velocity for zonal planetary wave one. It turns out that the teleconnection structure in the middle and upper troposphere differs considerably between the two regimes of the polar vortex, while this is not the case at sea level. If the "polar vortex is strong", there exists "one" meridional dipole structure of geopotential height in the upper and middle troposphere, which is situated in the central North Atlantic. If the "polar vortex is weak", there exist "two" such dipoles, one over the western and one over the eastern North Atlantic. Storm tracks (and precipitation related with these) are determined by mid and upper tropospheric conditions and we find significant differences of these parameters between the stratospheric regimes. For the strong polar vortex regime, in case of a negative upper tropospheric "NAO" index we find a blocking height situation over the Northeast Atlantic and the strongest storm track of all. It is reaching far north into the Arctic Ocean and has a secondary maximum over the Denmark Strait. Such storm track is not found in composites based on a classic NAO defined by surface pressure differences between the Icelandic Low and the Azores High. Our results show that it is essential to include the state of the upper dynamic boundary conditions (the polar vortex strength) in any study of the variability over the North Atlantic. Climate forecast based solely on the forecast of a "classic NAO" and further statistical downscaling may lead to the wrong conclusions if the state of the polar vortex is not considered as well. |
author2 |
Max Planck Institute for Meteorology (MPI-M) Max-Planck-Gesellschaft Centre for Atmospheric Science Cambridge, UK University of Cambridge UK (CAM) |
format |
Article in Journal/Newspaper |
author |
Walter, K. Graf, H.-F. |
author_facet |
Walter, K. Graf, H.-F. |
author_sort |
Walter, K. |
title |
The North Atlantic variability structure, storm tracks, and precipitation depending on the polar vortex strength |
title_short |
The North Atlantic variability structure, storm tracks, and precipitation depending on the polar vortex strength |
title_full |
The North Atlantic variability structure, storm tracks, and precipitation depending on the polar vortex strength |
title_fullStr |
The North Atlantic variability structure, storm tracks, and precipitation depending on the polar vortex strength |
title_full_unstemmed |
The North Atlantic variability structure, storm tracks, and precipitation depending on the polar vortex strength |
title_sort |
north atlantic variability structure, storm tracks, and precipitation depending on the polar vortex strength |
publisher |
HAL CCSD |
publishDate |
2004 |
url |
https://hal.science/hal-00301446 https://hal.science/hal-00301446/document https://hal.science/hal-00301446/file/acpd-4-6127-2004.pdf |
geographic |
Arctic Arctic Ocean |
geographic_facet |
Arctic Arctic Ocean |
genre |
Arctic Arctic Ocean Denmark Strait North Atlantic Northeast Atlantic |
genre_facet |
Arctic Arctic Ocean Denmark Strait North Atlantic Northeast Atlantic |
op_source |
ISSN: 1680-7367 EISSN: 1680-7375 Atmospheric Chemistry and Physics Discussions https://hal.science/hal-00301446 Atmospheric Chemistry and Physics Discussions, 2004, 4 (5), pp.6127-6148 |
op_relation |
hal-00301446 https://hal.science/hal-00301446 https://hal.science/hal-00301446/document https://hal.science/hal-00301446/file/acpd-4-6127-2004.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1782331646736859136 |