Equatorial mountain torques and cold surge preconditioning
International audience The evolution of the two components of the equatorial mountain torque (EMT) applied by mountains on the atmosphere is analyzed in the NCEP reanalysis. A strong lagged relationship between the EMT component along the Greenwich axis TM1 and the EMT component along the 90°E axis...
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ftepunivpsaclay:oai:HAL:hal-01136866v1 2024-06-09T07:40:15+00:00 Equatorial mountain torques and cold surge preconditioning Mailler, Sylvain Lott, François École des Ponts ParisTech (ENPC) Laboratoire de Météorologie Dynamique (UMR 8539) (LMD) Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris École normale supérieure - Paris (ENS-PSL) Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-École normale supérieure - Paris (ENS-PSL) Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL) 2010 https://hal.science/hal-01136866 https://hal.science/hal-01136866/document https://hal.science/hal-01136866/file/2010jas33822E1.pdf https://doi.org/10.1175/2010jas3382.1 en eng HAL CCSD American Meteorological Society info:eu-repo/semantics/altIdentifier/doi/10.1175/2010jas3382.1 hal-01136866 https://hal.science/hal-01136866 https://hal.science/hal-01136866/document https://hal.science/hal-01136866/file/2010jas33822E1.pdf doi:10.1175/2010jas3382.1 info:eu-repo/semantics/OpenAccess ISSN: 0022-4928 EISSN: 1520-0469 Journal of the Atmospheric Sciences https://hal.science/hal-01136866 Journal of the Atmospheric Sciences, 2010, 67 (6), pp.2101-2120. ⟨10.1175/2010jas3382.1⟩ [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environment [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology info:eu-repo/semantics/article Journal articles 2010 ftepunivpsaclay https://doi.org/10.1175/2010jas3382.1 2024-05-16T12:40:51Z International audience The evolution of the two components of the equatorial mountain torque (EMT) applied by mountains on the atmosphere is analyzed in the NCEP reanalysis. A strong lagged relationship between the EMT component along the Greenwich axis TM1 and the EMT component along the 90°E axis TM2 is found, with a pronounced signal on TM1 followed by a signal of opposite sign on TM2. It is shown that this result holds for themajor massifs (Antarctica, the Tibetan Plateau, the Rockies, and the Andes) if a suitable axis systemis used for each of them. For the midlatitude mountains, this relationship is in part associated with the development of cold surges. Following these results, two hypotheses are made: (i) the mountain forcing on the atmosphere is well measured by the regional EMTs and (ii) this forcing partly drives the cold surges. To support these, a purely dynamical linear model is proposed: it is written on the sphere, uses an f-plane quasigeostrophic approximation, and includes the mountain forcings. In this model, a positive (negative) peak in TM1 produced by a mountain massif in the Northern (Southern) Hemisphere is due to a large-scale high surface pressure anomaly poleward of the massif. At a later stage, high pressure and low temperature anomalies develop in the lower troposphere east of the mountain, explaining the signal on TM2 and providing the favorable conditions for the cold surge development. It is concluded that the EMT is a good measure of the dynamical forcing of the atmospheric flow by the mountains and that the poleward forces exerted by mountains on the atmosphere are substantial drivers of the cold surges, at least in their early stage. Therefore, the EMT time series can be an important diagnostic to assess the representation of mountains in general circulation models. © 2010 American Meteorological Society. Article in Journal/Newspaper Antarc* Antarctica École Polytechnique, Université Paris-Saclay: HAL Greenwich Journal of the Atmospheric Sciences 67 6 2101 2120 |
institution |
Open Polar |
collection |
École Polytechnique, Université Paris-Saclay: HAL |
op_collection_id |
ftepunivpsaclay |
language |
English |
topic |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environment [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology |
spellingShingle |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environment [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology Mailler, Sylvain Lott, François Equatorial mountain torques and cold surge preconditioning |
topic_facet |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environment [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology |
description |
International audience The evolution of the two components of the equatorial mountain torque (EMT) applied by mountains on the atmosphere is analyzed in the NCEP reanalysis. A strong lagged relationship between the EMT component along the Greenwich axis TM1 and the EMT component along the 90°E axis TM2 is found, with a pronounced signal on TM1 followed by a signal of opposite sign on TM2. It is shown that this result holds for themajor massifs (Antarctica, the Tibetan Plateau, the Rockies, and the Andes) if a suitable axis systemis used for each of them. For the midlatitude mountains, this relationship is in part associated with the development of cold surges. Following these results, two hypotheses are made: (i) the mountain forcing on the atmosphere is well measured by the regional EMTs and (ii) this forcing partly drives the cold surges. To support these, a purely dynamical linear model is proposed: it is written on the sphere, uses an f-plane quasigeostrophic approximation, and includes the mountain forcings. In this model, a positive (negative) peak in TM1 produced by a mountain massif in the Northern (Southern) Hemisphere is due to a large-scale high surface pressure anomaly poleward of the massif. At a later stage, high pressure and low temperature anomalies develop in the lower troposphere east of the mountain, explaining the signal on TM2 and providing the favorable conditions for the cold surge development. It is concluded that the EMT is a good measure of the dynamical forcing of the atmospheric flow by the mountains and that the poleward forces exerted by mountains on the atmosphere are substantial drivers of the cold surges, at least in their early stage. Therefore, the EMT time series can be an important diagnostic to assess the representation of mountains in general circulation models. © 2010 American Meteorological Society. |
author2 |
École des Ponts ParisTech (ENPC) Laboratoire de Météorologie Dynamique (UMR 8539) (LMD) Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris École normale supérieure - Paris (ENS-PSL) Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-École normale supérieure - Paris (ENS-PSL) Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL) |
format |
Article in Journal/Newspaper |
author |
Mailler, Sylvain Lott, François |
author_facet |
Mailler, Sylvain Lott, François |
author_sort |
Mailler, Sylvain |
title |
Equatorial mountain torques and cold surge preconditioning |
title_short |
Equatorial mountain torques and cold surge preconditioning |
title_full |
Equatorial mountain torques and cold surge preconditioning |
title_fullStr |
Equatorial mountain torques and cold surge preconditioning |
title_full_unstemmed |
Equatorial mountain torques and cold surge preconditioning |
title_sort |
equatorial mountain torques and cold surge preconditioning |
publisher |
HAL CCSD |
publishDate |
2010 |
url |
https://hal.science/hal-01136866 https://hal.science/hal-01136866/document https://hal.science/hal-01136866/file/2010jas33822E1.pdf https://doi.org/10.1175/2010jas3382.1 |
geographic |
Greenwich |
geographic_facet |
Greenwich |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_source |
ISSN: 0022-4928 EISSN: 1520-0469 Journal of the Atmospheric Sciences https://hal.science/hal-01136866 Journal of the Atmospheric Sciences, 2010, 67 (6), pp.2101-2120. ⟨10.1175/2010jas3382.1⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1175/2010jas3382.1 hal-01136866 https://hal.science/hal-01136866 https://hal.science/hal-01136866/document https://hal.science/hal-01136866/file/2010jas33822E1.pdf doi:10.1175/2010jas3382.1 |
op_rights |
info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.1175/2010jas3382.1 |
container_title |
Journal of the Atmospheric Sciences |
container_volume |
67 |
container_issue |
6 |
container_start_page |
2101 |
op_container_end_page |
2120 |
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1801383697305305088 |