Lower-Tropospheric Eddy Momentum Fluxes in Idealized Models and Reanalysis Data

In Earth’s atmosphere eddy momentum fluxes (EMFs) are largest in the upper troposphere, but EMFs in the lower troposphere, although modest in amplitude, have an intriguing structure. To document this structure, the EMFs in the lower tropospheres of a two-layer quasigeostrophic model, a primitive equ...

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Autores: Lutsko, Nicholas J., Held, Isaac M., Zurita-Gotor, Pablo, O’Rourke, Amanda K.
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2017
País:España
Institución:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/185479
Acceso en línea:http://hdl.handle.net/10261/185479
Access Level:acceso abierto
Palabra clave:Dynamics
Eddies
Fluxes
Waves
Atmosphere
Jets
Angular momentum
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spelling Lower-Tropospheric Eddy Momentum Fluxes in Idealized Models and Reanalysis DataLutsko, Nicholas J.Held, Isaac M.Zurita-Gotor, PabloO’Rourke, Amanda K.DynamicsEddiesFluxesWavesAtmosphereJetsAngular momentumIn Earth’s atmosphere eddy momentum fluxes (EMFs) are largest in the upper troposphere, but EMFs in the lower troposphere, although modest in amplitude, have an intriguing structure. To document this structure, the EMFs in the lower tropospheres of a two-layer quasigeostrophic model, a primitive equation model, and the Southern Hemisphere of a reanalysis dataset are investigated. The lower-tropospheric EMFs are very similar in the cores of the jets in both models and the reanalysis data, with EMF divergence (opposing the upper-tropospheric convergence) due to relatively long waves with slow eastward phase speeds and EMF divergence (as in the upper troposphere) due to shorter waves with faster eastward phase speeds. As the two-layer model is able to capture the EMF divergence by long waves, a qualitative picture of the underlying dynamics is proposed that relies on the negative potential vorticity gradient in the lower layer of the model. Eddies excited by baroclinic instability mix efficiently through a wide region in the lower layer, centered on the latitude of maximum westerlies and encompassing the lower-layer critical latitudes. Near these critical latitudes, the mixing is enhanced, resulting in increased EMF convergence, with compensating EMF divergence in the center of the jet. The EMF convergence at faster phase speeds is due to deep eddies that propagate on the upper-tropospheric potential vorticity gradient.Nicholas Lutsko was supported by NSF Grant DGE 1148900 and Pablo Zurita-Gotor thanks the Cooperative Institute for Climate Science at Princeton University for support during summer 2016.Peer reviewedAmerican Meteorological SocietyNational Science Foundation (US)Princeton UniversityConsejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]201920192017info:eu-repo/semantics/articlehttp://purl.org/coar/resource_type/c_6501Publisher's versioninfo:eu-repo/semantics/publishedVersionhttp://hdl.handle.net/10261/185479reponame:DIGITAL.CSIC. Repositorio Institucional del CSICinstname:Consejo Superior de Investigaciones Científicas (CSIC)Ingléshttps://doi.org/10.1175/JAS-D-17-0099.1Síinfo:eu-repo/semantics/openAccessoai:digital.csic.es:10261/1854792026-05-22T06:33:51Z
dc.title.none.fl_str_mv Lower-Tropospheric Eddy Momentum Fluxes in Idealized Models and Reanalysis Data
title Lower-Tropospheric Eddy Momentum Fluxes in Idealized Models and Reanalysis Data
spellingShingle Lower-Tropospheric Eddy Momentum Fluxes in Idealized Models and Reanalysis Data
Lutsko, Nicholas J.
Dynamics
Eddies
Fluxes
Waves
Atmosphere
Jets
Angular momentum
title_short Lower-Tropospheric Eddy Momentum Fluxes in Idealized Models and Reanalysis Data
title_full Lower-Tropospheric Eddy Momentum Fluxes in Idealized Models and Reanalysis Data
title_fullStr Lower-Tropospheric Eddy Momentum Fluxes in Idealized Models and Reanalysis Data
title_full_unstemmed Lower-Tropospheric Eddy Momentum Fluxes in Idealized Models and Reanalysis Data
title_sort Lower-Tropospheric Eddy Momentum Fluxes in Idealized Models and Reanalysis Data
dc.creator.none.fl_str_mv Lutsko, Nicholas J.
Held, Isaac M.
Zurita-Gotor, Pablo
O’Rourke, Amanda K.
author Lutsko, Nicholas J.
author_facet Lutsko, Nicholas J.
Held, Isaac M.
Zurita-Gotor, Pablo
O’Rourke, Amanda K.
author_role author
author2 Held, Isaac M.
Zurita-Gotor, Pablo
O’Rourke, Amanda K.
author2_role author
author
author
dc.contributor.none.fl_str_mv National Science Foundation (US)
Princeton University
Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]
dc.subject.none.fl_str_mv Dynamics
Eddies
Fluxes
Waves
Atmosphere
Jets
Angular momentum
topic Dynamics
Eddies
Fluxes
Waves
Atmosphere
Jets
Angular momentum
description In Earth’s atmosphere eddy momentum fluxes (EMFs) are largest in the upper troposphere, but EMFs in the lower troposphere, although modest in amplitude, have an intriguing structure. To document this structure, the EMFs in the lower tropospheres of a two-layer quasigeostrophic model, a primitive equation model, and the Southern Hemisphere of a reanalysis dataset are investigated. The lower-tropospheric EMFs are very similar in the cores of the jets in both models and the reanalysis data, with EMF divergence (opposing the upper-tropospheric convergence) due to relatively long waves with slow eastward phase speeds and EMF divergence (as in the upper troposphere) due to shorter waves with faster eastward phase speeds. As the two-layer model is able to capture the EMF divergence by long waves, a qualitative picture of the underlying dynamics is proposed that relies on the negative potential vorticity gradient in the lower layer of the model. Eddies excited by baroclinic instability mix efficiently through a wide region in the lower layer, centered on the latitude of maximum westerlies and encompassing the lower-layer critical latitudes. Near these critical latitudes, the mixing is enhanced, resulting in increased EMF convergence, with compensating EMF divergence in the center of the jet. The EMF convergence at faster phase speeds is due to deep eddies that propagate on the upper-tropospheric potential vorticity gradient.
publishDate 2017
dc.date.none.fl_str_mv 2017
2019
2019
dc.type.none.fl_str_mv info:eu-repo/semantics/article
http://purl.org/coar/resource_type/c_6501
Publisher's version
info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/10261/185479
url http://hdl.handle.net/10261/185479
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv https://doi.org/10.1175/JAS-D-17-0099.1
Sí
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.publisher.none.fl_str_mv American Meteorological Society
publisher.none.fl_str_mv American Meteorological Society
dc.source.none.fl_str_mv reponame:DIGITAL.CSIC. Repositorio Institucional del CSIC
instname:Consejo Superior de Investigaciones Científicas (CSIC)
instname_str Consejo Superior de Investigaciones Científicas (CSIC)
reponame_str DIGITAL.CSIC. Repositorio Institucional del CSIC
collection DIGITAL.CSIC. Repositorio Institucional del CSIC
repository.name.fl_str_mv
repository.mail.fl_str_mv
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