On the dynamical nature of Saturn's North Polar hexagon
International audience An explanation of long-lived Saturn's North Polar hexagonal circumpolar jet in terms of instability of the coupled system polar vortex - circumpolar jet is proposed in the framework of the rotating shallow water model, where scarcely known vertical structure of the Saturn...
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ftsorbonneuniv:oai:HAL:hal-01543521v1 2024-06-09T07:49:39+00:00 On the dynamical nature of Saturn's North Polar hexagon Rostami, Masoud Zeitlin, Vladimir Spiga, Aymeric 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) 2017 https://hal.sorbonne-universite.fr/hal-01543521 https://hal.sorbonne-universite.fr/hal-01543521/document https://hal.sorbonne-universite.fr/hal-01543521/file/Rostami2017_Saturn.pdf https://doi.org/10.1016/j.icarus.2017.06.006 en eng HAL CCSD Elsevier info:eu-repo/semantics/altIdentifier/doi/10.1016/j.icarus.2017.06.006 hal-01543521 https://hal.sorbonne-universite.fr/hal-01543521 https://hal.sorbonne-universite.fr/hal-01543521/document https://hal.sorbonne-universite.fr/hal-01543521/file/Rostami2017_Saturn.pdf doi:10.1016/j.icarus.2017.06.006 info:eu-repo/semantics/OpenAccess ISSN: 0019-1035 EISSN: 1090-2643 Icarus https://hal.sorbonne-universite.fr/hal-01543521 Icarus, 2017, ⟨10.1016/j.icarus.2017.06.006⟩ http://www.sciencedirect.com/science/article/pii/S0019103516305978 NPV Hexagon North polar vortex Rotating Shallow Water Model Barotropic Instability Saturn's Hexagon [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph] [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] info:eu-repo/semantics/article Journal articles 2017 ftsorbonneuniv https://doi.org/10.1016/j.icarus.2017.06.006 2024-05-16T23:59:36Z International audience An explanation of long-lived Saturn's North Polar hexagonal circumpolar jet in terms of instability of the coupled system polar vortex - circumpolar jet is proposed in the framework of the rotating shallow water model, where scarcely known vertical structure of the Saturn's atmosphere is averaged out. The absence of a hexagonal structure at Saturn's South Pole is explained similarly. By using the latest state-of-the-art observed winds in Saturn's polar regions a detailed linear stability analysis of the circumpolar jet is performed (i) excluding (\jet-only" configuration), and (2) including ("jet+vortex" configuration) the north polar vortex in the system. A domain of parameters: latitude of the circumpolar jet and curvature of its azimuthal velocity profile, where the most unstable mode of the system has azimuthal wavenumber 6, is identified. Fully nonlinear simulations are then performed, initialized either with the most unstable mode of small amplitude, or with the random combination of unstable modes. It is shown that developing barotropic instability of the "jet+vortex" system produces a long-living structure akin to the observed hexagon, which is not the case of the "jet-only" system, which was studied in this context in a number of papers in literature. The north polar vortex, thus, plays a decisive dynamical role. The influence of moist convection, which was recently suggested to be at the origin of Saturn's north polar vortex system in the literature, is investigated in the framework of the model and does not alter the conclusions. Article in Journal/Newspaper South pole HAL Sorbonne Université South Pole Icarus 297 59 70 |
institution |
Open Polar |
collection |
HAL Sorbonne Université |
op_collection_id |
ftsorbonneuniv |
language |
English |
topic |
NPV Hexagon North polar vortex Rotating Shallow Water Model Barotropic Instability Saturn's Hexagon [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph] [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] |
spellingShingle |
NPV Hexagon North polar vortex Rotating Shallow Water Model Barotropic Instability Saturn's Hexagon [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph] [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] Rostami, Masoud Zeitlin, Vladimir Spiga, Aymeric On the dynamical nature of Saturn's North Polar hexagon |
topic_facet |
NPV Hexagon North polar vortex Rotating Shallow Water Model Barotropic Instability Saturn's Hexagon [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph] [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] |
description |
International audience An explanation of long-lived Saturn's North Polar hexagonal circumpolar jet in terms of instability of the coupled system polar vortex - circumpolar jet is proposed in the framework of the rotating shallow water model, where scarcely known vertical structure of the Saturn's atmosphere is averaged out. The absence of a hexagonal structure at Saturn's South Pole is explained similarly. By using the latest state-of-the-art observed winds in Saturn's polar regions a detailed linear stability analysis of the circumpolar jet is performed (i) excluding (\jet-only" configuration), and (2) including ("jet+vortex" configuration) the north polar vortex in the system. A domain of parameters: latitude of the circumpolar jet and curvature of its azimuthal velocity profile, where the most unstable mode of the system has azimuthal wavenumber 6, is identified. Fully nonlinear simulations are then performed, initialized either with the most unstable mode of small amplitude, or with the random combination of unstable modes. It is shown that developing barotropic instability of the "jet+vortex" system produces a long-living structure akin to the observed hexagon, which is not the case of the "jet-only" system, which was studied in this context in a number of papers in literature. The north polar vortex, thus, plays a decisive dynamical role. The influence of moist convection, which was recently suggested to be at the origin of Saturn's north polar vortex system in the literature, is investigated in the framework of the model and does not alter the conclusions. |
author2 |
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 |
Rostami, Masoud Zeitlin, Vladimir Spiga, Aymeric |
author_facet |
Rostami, Masoud Zeitlin, Vladimir Spiga, Aymeric |
author_sort |
Rostami, Masoud |
title |
On the dynamical nature of Saturn's North Polar hexagon |
title_short |
On the dynamical nature of Saturn's North Polar hexagon |
title_full |
On the dynamical nature of Saturn's North Polar hexagon |
title_fullStr |
On the dynamical nature of Saturn's North Polar hexagon |
title_full_unstemmed |
On the dynamical nature of Saturn's North Polar hexagon |
title_sort |
on the dynamical nature of saturn's north polar hexagon |
publisher |
HAL CCSD |
publishDate |
2017 |
url |
https://hal.sorbonne-universite.fr/hal-01543521 https://hal.sorbonne-universite.fr/hal-01543521/document https://hal.sorbonne-universite.fr/hal-01543521/file/Rostami2017_Saturn.pdf https://doi.org/10.1016/j.icarus.2017.06.006 |
geographic |
South Pole |
geographic_facet |
South Pole |
genre |
South pole |
genre_facet |
South pole |
op_source |
ISSN: 0019-1035 EISSN: 1090-2643 Icarus https://hal.sorbonne-universite.fr/hal-01543521 Icarus, 2017, ⟨10.1016/j.icarus.2017.06.006⟩ http://www.sciencedirect.com/science/article/pii/S0019103516305978 |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1016/j.icarus.2017.06.006 hal-01543521 https://hal.sorbonne-universite.fr/hal-01543521 https://hal.sorbonne-universite.fr/hal-01543521/document https://hal.sorbonne-universite.fr/hal-01543521/file/Rostami2017_Saturn.pdf doi:10.1016/j.icarus.2017.06.006 |
op_rights |
info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.1016/j.icarus.2017.06.006 |
container_title |
Icarus |
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297 |
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59 |
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70 |
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