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dc.contributor.author
Pulido, Manuel Arturo
dc.contributor.author
Polavarapu, Saroja
dc.contributor.author
Shepherd, Theodore
dc.contributor.author
Thuburn, John
dc.date.available
2017-05-31T21:53:08Z
dc.date.issued
2011-09
dc.identifier.citation
Pulido, Manuel Arturo; Polavarapu, Saroja; Shepherd, Theodore; Thuburn, John; Estimation of optimal gravity wave parameters for climate models using data assimilation; John Wiley & Sons Ltd; Quarterly Journal Of The Royal Meteorological Society; 138; 663; 9-2011; 298-309
dc.identifier.issn
0035-9009
dc.identifier.uri
http://hdl.handle.net/11336/17238
dc.description.abstract
There is a current need to constrain the parameters of gravity wave drag schemes in climate models using observational information instead of tuning them subjectively. In this work, an inverse technique is developed using data assimilation principles to estimate gravity wave parameters.  Because most gravity wave drag schemes assume instantaneous vertical propagation of gravity waves within a column, observations in a single column can be used to formulate a one-dimensional assimilation problem to estimate the unknown parameters. We define a cost function that measures the differences between the unresolved drag inferred from observations (referred to here as the `observed´ gravity wave drag) and the gravity wave drag calculated with a parameterisation scheme. The geometry of the cost function presents some difficulties, including multiple minima and ill-conditioning because of the non-independence of the gravity-wave parameters. To overcome these difficulties we propose a genetic algorithm to minimize the cost function, which provides a robust parameter estimation over a broad range of prescribed `true´ parameters. When real experiments using an independent estimate of the `observed´ gravity wave drag are performed, physically unrealistic values of the parameters can result due to the non-independence of the parameters. However by constraining one of the parameters to lie within a physically realistic range, this degeneracy is broken and the other parameters are also found to lie within physically realistic ranges. This argues for the essential physical self-consistency of the gravity wave scheme. A much better fit to the observed gravity wave drag at high latitudes is obtained when the parameters are allowed to vary with latitude. However, a close fit can be obtained either in the upper or the lower part of the profiles, but not both at the same time. This result is a consequence of assuming an isotropic launch spectrum. The changes of sign in the gravity wave drag found in the tropical lower stratosphere, which are associated with part of the QBO forcing, cannot be captured by the parameterisation with optimal parameters.
dc.format
application/pdf
dc.language.iso
eng
dc.publisher
John Wiley & Sons Ltd
dc.rights
info:eu-repo/semantics/restrictedAccess
dc.rights.uri
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
dc.subject
Subgrid Scale
dc.subject
Genetic Algorithm
dc.subject
Missing Forcing
dc.subject.classification
Meteorología y Ciencias Atmosféricas
dc.subject.classification
Ciencias de la Tierra y relacionadas con el Medio Ambiente
dc.subject.classification
CIENCIAS NATURALES Y EXACTAS
dc.title
Estimation of optimal gravity wave parameters for climate models using data assimilation
dc.type
info:eu-repo/semantics/article
dc.type
info:ar-repo/semantics/artículo
dc.type
info:eu-repo/semantics/publishedVersion
dc.date.updated
2017-05-17T13:46:52Z
dc.identifier.eissn
1477-870X
dc.journal.volume
138
dc.journal.number
663
dc.journal.pagination
298-309
dc.journal.pais
Reino Unido
dc.journal.ciudad
Reading
dc.description.fil
Fil: Pulido, Manuel Arturo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Modelado e Innovación Tecnológica. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura. Instituto de Modelado e Innovación Tecnologica; Argentina. University of Toronto; Canadá
dc.description.fil
Fil: Polavarapu, Saroja. Environment Canada; Canadá
dc.description.fil
Fil: Shepherd, Theodore. University of Toronto; Canadá
dc.description.fil
Fil: Thuburn, John. University Of Exeter; Reino Unido
dc.journal.title
Quarterly Journal Of The Royal Meteorological Society
dc.relation.alternativeid
info:eu-repo/semantics/altIdentifier/url/http://onlinelibrary.wiley.com/doi/10.1002/qj.932/abstract
dc.relation.alternativeid
info:eu-repo/semantics/altIdentifier/doi/http://dx.doi.org/10.1002/qj.932


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