简介:Thetechniqueoncomputingthehorizontalpressuregradientforce(PGF)inRegCM2isimprovedwiththeerrorsubtractionmethod.Moreover,theregionalclimateinJuneof1991inChinaissimulatedbyemployingtheRegCM2.ComparisonwithotherschemesforcomputingthePGFshowsthattheerrorsubtractionmethodcaneffectivelyreducetheerrorofthePGF,improvethesimulationofwindsandalleviatethespuriousprecipitationinsteeptopographicareas.Furthermore,thesimulationofprecipitationinotherareasisinbetteraccordancewiththeobservation.
简介:TheNCARcommunityclimatemodelwasrunfor20yearsandthesimulatedEastAsianclimatewasanalyzedandcheckedagainsttheobservationdata.Itisfoundthatthelarge-scalefeaturesoftheEastAsiaclimateweresimulatedprettywellbythemodel,thoughtherearestillsomediscrepanciesbetweenthemodeloutputandtheobservation.Thesimulatedgeopotentialheight,windandtemperaturefieldsareveryclosetotheobservations.Thelargescalesystemssuchassubtropicalhigh.Mongoliahigh,IndianlowwhichhaveimportantinfluenceontheEastAsiamonsoonalsosimulatedprettywell.Itisalsofoundthatthemoisturefieldisnotsimulatedsowellasthosefieldsmentionedabove.Thesimulatedprecipitationisratherdifferentfromtheobservations.ThesesuggestthatsomephysicalprocessesintheCCM2needtobeimproved.
简介:Aseriesofidealizedmodelsimulationsareanalyzedtodeterminethesensitivityofmodelresultstodifferentconfigurationsofthelateralboundaryconditions(LBCs)insimulatingmesoscaleshallowconvectionoverhillyterrain.Inthesimulationswithsteadythermalforcingatthemodelsurface,aradiationconditionatbothboundariesisthebestchoiceunderhighwindconditions,andthebestresultsareproducedwhenboththenormalvelocitiesandthetemperaturearetreatedwiththeradiationschemeinwhichthephasespeedisthesamefordifferentvariables.Whenthebackgroundwindspeedisreasonablysmall,theLBCconfigurationwitheithertheradiationorthezerogradientconditionatbothboundariestendstomakethenumericalsolutionunstable.Thechoiceofaconstantconditionattheinflowboundaryandaradiationoutflowboundaryconditionisappropriateinmostcases.Inthesimulationswithdiurnalthermalforcingatthemodelsurface,differentLBCschemesarecombinedtogethertoreducespurioussignalsinducedbytheoutflowboundary.Aspecificationinflowboundarycondition,inwhichthevelocityfieldsattheinflowboundaryareprovidedusingthetime-dependentresultsofasimulationwithperiodicLBCsoveraflatdomain,istestedandtheresultsindicatethatthespecificationconditionattheinflowboundarymakesitpossibletouseasmallermodeldomaintoobtainreasonableresults.Themodelhorizontaldomainlengthshouldbegreaterthanacriticallength,whichdependsonthedomaindepthHandtheanglebetweengravitywavephaselinesandthevertical.Anestimateofminimumdomainlengthisgivenby[(H-zi)/πU]√N2L2x-4π2U2,whereNandUarethebackgroundstabilityandwindspeed,respectively,Lxisthetypicalgravitywavelengthscale,andziistheconvectiveboundarylayer(CBL)depth.
简介:A2m~3isothermalcloudchambermainlyforicenucleationresearchisdescribedinthispaper.Itsstructure,attachedinstrumentsandexperimentalproceduresarealsopresented.TheexperimentsofdeterminingtheicenucleieffectivenessfortheAgl-containingaerosolsproducedbythreeformulationshavebeenconductedandtheresultshavebeencomparedwiththoseoftheCSU960-literisothermalcloudchamber.Allexperimentalresultsshowthatthechamberhasadvantagesofstableperformanceandreproducibility.Itwouldbeexpectedtobecomeausefulexperimentalfacilityforicenucleationresearch.
简介:THE2-DNUMERICALSTUDYONTHEPRINCIPLESOFRAIN-ENHANCEMENTANDHAIL-SUPPRESSIONINCONVECTIVECLOUDSMaoYuhua(毛玉华)andHuZhijin(胡志晋)THE2-D...