简介:AssimilatingsatelliteradiancesintoNumericalWeatherPrediction(NWP)modelshasbecomeanimportantapproachtoincreasetheaccuracyofnumericalweatherforecasting.Inthisstudy,theassimilationtechniqueschemewasemployedinNOAA’sSTMAS(Space-TimeMultiscaleAnalysisSystem)toassimilateAMSU-Aradiancesdata.Channelselectionsensitivityexperimentswereconductedonassimilatedsatellitedatainthefirstplace.Then,realcaseanalysisofAMSU-Adataassimilationwasperformed.Theanalysisresultsshowedthat,followingassimilatingofAMSU-Achannels5-11inSTMAS,theobjectivefunctionquicklyconverged,andthechannelverticalresponsewasconsistentwiththeAMSU-Aweightingfunctiondistribution,whichsuggeststhatthechannelscanbeusedintheassimilationofsatellitedatainSTMAS.WiththecaseoftheTyphoonMorakotinTaiwanIslandinAugust2009asanexample,experimentsonassimilatedandunassimilatedAMSU-AradiancesdataweredesignedtoanalyzetheimpactoftheassimilationofsatellitedataonSTMAS.TheresultsdemonstratedthatassimilationofAMSU-Adataprovidedmoreaccuratepredictionoftheprecipitationregionandintensity,andespecially,itimprovedthe0-6hprecipitationforecastsignificantly.
简介:Inthispaper,theforecastingequationsofa2nd-orderspace-timedifferentialremainderarededucedfromtheNavier-StokesprimitiveequationsandEulerianoperatorbyTaylor-seriesexpansion.Hereweintroduceacubicsplinenumericalmodel(SplineModelforshort),whichiswithaquasi-Lagrangiantime-splitintegrationschemeoffittingcubicspline/bicubicsurfacetoallphysicalvariablefieldsintheatmosphericequationsonsphericaldiscretelatitude-longitudemesh.Anewalgorithmof'fittingcubicspline—timestepintegration—fittingcubicspline—……'isdevelopedtodeterminetheirfirst-and2nd-orderderivativesandtheirupstreampointsfortimediscreteintegraltothegoverningequationsinSplineModel.AndthecubicsplinefunctionanditsmathematicalpolaritiesarealsodiscussedtounderstandtheSplineModel’smathematicalfoundationofnumericalanalysis.ItispointedoutthattheSplineModelhasmathematicallawsof'convergence'ofthecubicsplinefunctionscontractingtotheoriginalfunctionsaswellasits1st-orderand2nd-orderderivatives.The'optimality'ofthe2nd-orderderivativeofthecubicsplinefunctionsisoptimalapproximationtothatoftheoriginalfunctions.Inaddition,aHermitebicubicpatchisequivalenttooperateonagridfora2nd-orderderivativevariablefield.Besides,theslopesandcurvaturesofacentraldifferenceareidentifiedrespectively,withasmoothingcoefficientof1/3,three-pointsmoothingofthatofacubicspline.Thentheslopesandcurvaturesofacentraldifferencearecalculatedfromthesmoothingcoefficient1/3andthree-pointsmoothingofthatofacubicspline,respectively.Furthermore,aglobalsimulationcaseofadiabatic,non-frictionaland'incompressible'modelatmosphereisshownwiththequasi-LagrangiantimeintegrationbyusingaglobalSplineModel,whoseinitialconditioncomesfromtheNCEPreanalysisdata,alongwithquasi-uniformlatitude-longitudegridsandtheso-called'shallowatmosphere'Navier-Stokesprimitiveequationsinthes