Mid-level convection in a warm conveyor belt accelerates the jet stream
Jet streams and potential vorticity (PV) gradients along upper-level ridges and troughs form a waveguide that governs midlatitude dynamics. Warm conveyor belt (WCB) outflows often inject low-PV air into ridges and their representation is seen as a source of uncertainty for downstream forecasts. Rece...
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Language: | English |
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HAL CCSD
2020
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Online Access: | https://hal.archives-ouvertes.fr/hal-02999222 https://hal.archives-ouvertes.fr/hal-02999222/document https://hal.archives-ouvertes.fr/hal-02999222/file/wcd-2020-53.pdf https://doi.org/10.5194/wcd-2020-53 |
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ftccsdartic:oai:HAL:hal-02999222v1 |
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Open Polar |
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Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
op_collection_id |
ftccsdartic |
language |
English |
topic |
[SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology |
spellingShingle |
[SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology Blanchard, Nicolas Pantillon, Florian Chaboureau, Jean-Pierre Delanoë, Julien Mid-level convection in a warm conveyor belt accelerates the jet stream |
topic_facet |
[SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology |
description |
Jet streams and potential vorticity (PV) gradients along upper-level ridges and troughs form a waveguide that governs midlatitude dynamics. Warm conveyor belt (WCB) outflows often inject low-PV air into ridges and their representation is seen as a source of uncertainty for downstream forecasts. Recent studies have highlighted the presence of mesoscale structures of negative PV in WCBs, the impact of which on large-scale dynamics is still debated. Here, fine-scale observations of cloud and wind structures acquired with airborne Doppler radar and dropsondes provide rare information on the WCB outflow of the Stalactite cyclone and the associated upper-level ridge on 2 October 2016 during the North Atlantic Waveguide and Downstream Impact Experiment. The observations reveal a complex tropopause structure with a high PV tongue separating the northwestern edge of the ridge in two parts, each with cirrus-type clouds and accompanied by a jet stream core, and bounded by a tropopause fold. A reference, convection-permitting simulation with full physics reproduces well the observed mesoscale structures and reveals the presence of elongated negative PV bands along the eastern jet stream core. In contrast, a sensitivity experiment with heat exchanges due to cloud processes cut off shows lower cloud tops, weaker jet stream cores, a ridge less extended westward, and the absence of negative PV bands. A Lagrangian analysis based on online trajectories shows that the anticyclonic branch of the WCB outflow feeds the eastern jet stream core in the reference simulation, while it is absent in the sensitivity experiment. The anticyclonic ascents and negative PV bands originate from the same region near the cyclone's bent-back front. The most rapid ascents coincide with mid-level convective cells identified by clustering analysis, which are located in a region of conditional instability below the jet stream core and above a low-level jet. Horizontal PV dipoles are found around these cells and with the negative poles reaching absolute ... |
author2 |
Laboratoire d'aérologie (LA) Université Toulouse III - Paul Sabatier (UT3) Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP) Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Université Fédérale Toulouse Midi-Pyrénées-Centre National d'Études Spatiales Toulouse (CNES)-Météo France-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Météo France-Centre National de la Recherche Scientifique (CNRS) Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS) Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS) |
format |
Report |
author |
Blanchard, Nicolas Pantillon, Florian Chaboureau, Jean-Pierre Delanoë, Julien |
author_facet |
Blanchard, Nicolas Pantillon, Florian Chaboureau, Jean-Pierre Delanoë, Julien |
author_sort |
Blanchard, Nicolas |
title |
Mid-level convection in a warm conveyor belt accelerates the jet stream |
title_short |
Mid-level convection in a warm conveyor belt accelerates the jet stream |
title_full |
Mid-level convection in a warm conveyor belt accelerates the jet stream |
title_fullStr |
Mid-level convection in a warm conveyor belt accelerates the jet stream |
title_full_unstemmed |
Mid-level convection in a warm conveyor belt accelerates the jet stream |
title_sort |
mid-level convection in a warm conveyor belt accelerates the jet stream |
publisher |
HAL CCSD |
publishDate |
2020 |
url |
https://hal.archives-ouvertes.fr/hal-02999222 https://hal.archives-ouvertes.fr/hal-02999222/document https://hal.archives-ouvertes.fr/hal-02999222/file/wcd-2020-53.pdf https://doi.org/10.5194/wcd-2020-53 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
https://hal.archives-ouvertes.fr/hal-02999222 2020 |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.5194/wcd-2020-53 hal-02999222 https://hal.archives-ouvertes.fr/hal-02999222 https://hal.archives-ouvertes.fr/hal-02999222/document https://hal.archives-ouvertes.fr/hal-02999222/file/wcd-2020-53.pdf doi:10.5194/wcd-2020-53 |
op_rights |
http://creativecommons.org/licenses/by/ info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.5194/wcd-2020-53 |
_version_ |
1766135407445016576 |
spelling |
ftccsdartic:oai:HAL:hal-02999222v1 2023-05-15T17:36:03+02:00 Mid-level convection in a warm conveyor belt accelerates the jet stream Blanchard, Nicolas Pantillon, Florian Chaboureau, Jean-Pierre Delanoë, Julien Laboratoire d'aérologie (LA) Université Toulouse III - Paul Sabatier (UT3) Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP) Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Université Fédérale Toulouse Midi-Pyrénées-Centre National d'Études Spatiales Toulouse (CNES)-Météo France-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Météo France-Centre National de la Recherche Scientifique (CNRS) Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS) Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS) 2020-11-10 https://hal.archives-ouvertes.fr/hal-02999222 https://hal.archives-ouvertes.fr/hal-02999222/document https://hal.archives-ouvertes.fr/hal-02999222/file/wcd-2020-53.pdf https://doi.org/10.5194/wcd-2020-53 en eng HAL CCSD info:eu-repo/semantics/altIdentifier/doi/10.5194/wcd-2020-53 hal-02999222 https://hal.archives-ouvertes.fr/hal-02999222 https://hal.archives-ouvertes.fr/hal-02999222/document https://hal.archives-ouvertes.fr/hal-02999222/file/wcd-2020-53.pdf doi:10.5194/wcd-2020-53 http://creativecommons.org/licenses/by/ info:eu-repo/semantics/OpenAccess https://hal.archives-ouvertes.fr/hal-02999222 2020 [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology info:eu-repo/semantics/preprint Preprints, Working Papers, . 2020 ftccsdartic https://doi.org/10.5194/wcd-2020-53 2020-12-23T22:40:39Z Jet streams and potential vorticity (PV) gradients along upper-level ridges and troughs form a waveguide that governs midlatitude dynamics. Warm conveyor belt (WCB) outflows often inject low-PV air into ridges and their representation is seen as a source of uncertainty for downstream forecasts. Recent studies have highlighted the presence of mesoscale structures of negative PV in WCBs, the impact of which on large-scale dynamics is still debated. Here, fine-scale observations of cloud and wind structures acquired with airborne Doppler radar and dropsondes provide rare information on the WCB outflow of the Stalactite cyclone and the associated upper-level ridge on 2 October 2016 during the North Atlantic Waveguide and Downstream Impact Experiment. The observations reveal a complex tropopause structure with a high PV tongue separating the northwestern edge of the ridge in two parts, each with cirrus-type clouds and accompanied by a jet stream core, and bounded by a tropopause fold. A reference, convection-permitting simulation with full physics reproduces well the observed mesoscale structures and reveals the presence of elongated negative PV bands along the eastern jet stream core. In contrast, a sensitivity experiment with heat exchanges due to cloud processes cut off shows lower cloud tops, weaker jet stream cores, a ridge less extended westward, and the absence of negative PV bands. A Lagrangian analysis based on online trajectories shows that the anticyclonic branch of the WCB outflow feeds the eastern jet stream core in the reference simulation, while it is absent in the sensitivity experiment. The anticyclonic ascents and negative PV bands originate from the same region near the cyclone's bent-back front. The most rapid ascents coincide with mid-level convective cells identified by clustering analysis, which are located in a region of conditional instability below the jet stream core and above a low-level jet. Horizontal PV dipoles are found around these cells and with the negative poles reaching absolute ... Report North Atlantic Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |