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dc.contributor.author
Ait-Chaalal, Farid
dc.contributor.author
Schneider, Tapio
dc.contributor.author
Meyer, Bettina
dc.contributor.author
Marston, J.B.
dc.date.accessioned
2018-12-19T18:32:15Z
dc.date.available
2017-06-12T02:52:11Z
dc.date.available
2018-12-19T18:32:15Z
dc.date.issued
2016-02
dc.identifier.issn
1367-2630
dc.identifier.other
10.1088/1367-2630/18/2/025019
en_US
dc.identifier.uri
http://hdl.handle.net/20.500.11850/114310
dc.identifier.doi
10.3929/ethz-b-000114310
dc.description.abstract
Atmospheric flows are governed by the equations of fluid dynamics. These equations are nonlinear, and consequently the hierarchy of cumulant equations is not closed. But because atmospheric flows are inhomogeneous and anisotropic, the nonlinearity may manifest itself only weakly through interactions of nontrivial mean fields with disturbances such as thermals or eddies. In such situations, truncations of the hierarchy of cumulant equations hold promise as a closure strategy. Here we show how truncations at second order can be used to model and elucidate the dynamics of turbulent atmospheric flows. Two examples are considered. First, we study the growth of a dry convective boundary layer, which is heated from below, leading to turbulent upward energy transport and growth of the boundary layer. We demonstrate that a quasilinear truncation of the equations of motion, in which interactions of disturbances among each other are neglected but interactions with mean fields are taken into account, can capture the growth of the convective boundary layer. However, it does not capture important turbulent transport terms in the turbulence kinetic energy budget. Second, we study the evolution of two-dimensional large-scale waves, which are representative of waves seen in Earth's upper atmosphere. We demonstrate that a cumulant expansion truncated at second order (CE2) can capture the evolution of such waves and their nonlinear interaction with the mean flow in some circumstances, for example, when the wave amplitude is small enough or the planetary rotation rate is large enough. However, CE2 fails to capture the flow evolution when strongly nonlinear eddy–eddy interactions that generate small-scale filaments in surf zones around critical layers become important. Higher-order closures can capture these missing interactions. The results point to new ways in which the dynamics of turbulent boundary layers may be represented in climate models, and they illustrate different classes of nonlinear processes that can control wave dissipation and angular momentum fluxes in the upper troposphere.
en_US
dc.format
application/pdf
en_US
dc.language.iso
en
en_US
dc.publisher
Institute of Physics
en_US
dc.rights.uri
http://creativecommons.org/licenses/by/3.0/
dc.subject
Turbulence
en_US
dc.subject
Quasi-linear approximation
en_US
dc.subject
Closure
en_US
dc.subject
Atmospheric boundary layer
en_US
dc.subject
Atmospheric convection
en_US
dc.subject
Large-scale atmospheric circulation
en_US
dc.subject
Jets
en_US
dc.title
Cumulant expansions for atmospheric flows
en_US
dc.type
Journal Article
dc.rights.license
Creative Commons Attribution 3.0 Unported
dc.date.published
2016-02-19
ethz.journal.title
New Journal of Physics
ethz.journal.volume
18
en_US
ethz.journal.abbreviated
New j. phys.
ethz.pages.start
025019
en_US
ethz.size
24 p.
en_US
ethz.version.deposit
publishedVersion
en_US
ethz.identifier.wos
ethz.identifier.scopus
ethz.identifier.nebis
001997538
ethz.publication.place
London
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich, direkt::00012 - Lehre und Forschung, direkt::00007 - Departemente, direkt::02330 - Departement Erdwissenschaften / Department of Earth Sciences::02704 - Geologisches Institut / Geological Institute::03991 - Schneider, Tapio (ehemalig)
en_US
ethz.leitzahl.certified
ETH Zürich::00002 - ETH Zürich, direkt::00012 - Lehre und Forschung, direkt::00007 - Departemente, direkt::02330 - Departement Erdwissenschaften / Department of Earth Sciences::02704 - Geologisches Institut / Geological Institute::03991 - Schneider, Tapio (ehemalig)
ethz.date.deposited
2017-06-12T02:53:50Z
ethz.source
ECIT
ethz.identifier.importid
imp5936543c0812e77910
ethz.ecitpid
pub:176088
ethz.eth
yes
en_US
ethz.availability
Open access
en_US
ethz.rosetta.installDate
2017-07-12T20:21:39Z
ethz.rosetta.lastUpdated
2018-12-19T18:32:31Z
ethz.rosetta.versionExported
true
ethz.COinS
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