CORRESPONDENCE Comments on ''A Semihydrostatic Theory of Gravity-Dominated Compressible Flow''

摘要: By extending the unified framework of Arakawa andKonor (2009), Dubos and Voitus (2014, hereafterDV14) describe construction a soundproofsemihydrostatic model.In this model, air parcels are constrained to remainclose their hydrostatic height. Accuracy at non-hydrostatic scales is ensured by retaining vertical ac-celeration, approximated as second Lagrangianderivative height, in mo-mentum budget. The constraint imposed on verticalpositionofairparcelsfiltersoutacousticwavesandgivesrise self-adjoint problem for Lagrange multiplieridentifiedasanonhydrostaticdisplacement—thatis,thedifference between actual height andtheir height.In final part paper, DV14 envisage an ap-plication model data assimilation ini-tialization purposes:Variational systems may benefit fromsuch accurate elimination acoustic waves, reducingthe optimization space. Similarly, it could be useful forinitialization purposes, avoiding transient generationof waves from initial flow. It also behelpful occasionally perform projection while in-tegratingthefullycompressibleEulerequations,especiallyafter physical parameterizations have acted, potentiallytriggering emission waves.Recently, Benacchio et al. (2014,hereafterBOK14)andtherelatedworkbyKleinetal.(2014) andBenacchio(2014) proposed blended semi-implicit soundproof–compressible motivating development withreference testing reducingtheamplitudeofacousticwavesgeneratedbyimbalancedinitial data. Discussing extension work tolarger scales, BOK14 referred approaches re-garding correct limiting such extension:Carefulconsiderationwillbeneededtoidentifythecorrectlarge-scalelimitingmodelinthelightofrecentsuggestionsof multiscale reduced models Durran (2008),Arakawa Konor (2009),andKonor (2014).The two excerpts reported above suggest exis-tence connection BOK14. Thiscomment aims clarifying thebenefit readers either paper.In BOK14, pseudoincompressible formulation fea-turing thermodynamic pressure was extended tocompressible dynamics byretrieving time derivativeterm potential temperature equation written