上層海流對臺(tái)風(fēng)的反應(yīng)

上層海流對臺(tái)風(fēng)的反應(yīng)演示文稿現(xiàn)在是1頁\一共有30頁\編輯于星期六Contents1.Introduction2.Reviewofobservations3.Amodeloftheupperoceanresponse4.SpecificationoftheEB-10/Eloisecase5.Overviewoftheresponse6.ComparisonofthemodelsolutionwiththeEB-10data7Numericalexperiments8.Conclusion現(xiàn)在是2頁\一共有30頁\編輯于星期六1.IntroductionQuestionWhatisthereasonforSSTresponsetoahurricaneandrightwardbias?2.Howdoestheresponsedependuponsuchfactorsasthehurricanetranslationspeed,theoceaninitialcondition,etc.?3.Whatroledononlocaldynamicsplayintheupperoceanresponse4.Isthereevidencethatair-seatransfercoefficientsincreasesignificantlyunderhurricaneconditions?現(xiàn)在是3頁\一共有30頁\編輯于星期六2.Reviewofobservationsa.HydrographicsurveysTable1HydrographicstudiesoftheseasurfacetemperatureresponsetohurricaneFig.1ResponseofSSTacrossthetrackofhurricaneElla&ResponseofsubsurfacetemperatureacrossthetrackofhurricaneElla現(xiàn)在是4頁\一共有30頁\編輯于星期六Fig2SSTaroundthetrackofhurricaneTess&TemperaturesectionABmadeacrossthetrackofTessb.Buoy/hurricaneencountersa.HydrographicsurveysFig.3NationalHurricaneCenterstormtracksofhurricanesEloise(1975)andBelle(1976)現(xiàn)在是5頁\一共有30頁\編輯于星期六1)EB-10/EloiseFig4MeteorologicalmeasurementsformEB-10duringthepassageofhurricaneEloise現(xiàn)在是6頁\一共有30頁\編輯于星期六Fig5.OceantemperaturefromEB-10duringandafterthepassageofHurricaneEloise現(xiàn)在是7頁\一共有30頁\編輯于星期六2)EB-04/EloiseFig6.Air-seameasurement(upper/lowerpanels)fromEB-04duringthepassageofEloise2)EB-15/EloiseFig7Air-seameasurement(upper/lowerpanels)fromEB-15duringthepassageofBelle現(xiàn)在是8頁\一共有30頁\編輯于星期六3.Amodeloftheupperoceanresponsea.ScalesandphysicalapproximationsFig8.Schematicplanviewofthenumericalmodel現(xiàn)在是9頁\一共有30頁\編輯于星期六Physicalapproximationsareasfollows:1)TheCoriolisparameterfisconstant,pressureishydrostatic,theBoussinespapproximationanddiffusiveprocessesareexcluded2)Density:Whereα=-3.3*10-4andβ=7.6*10-4aretheappropriatethermalandhalineexpansioncoefficientsandρ0=1.0235*103

kgm-3isthereferencedensity3)Theseasurfaceistreatedasarigidlid(excludesthebarotropicmode).4)Thesubthermoclineoceanistakenasinfinitydeepandunabletosustainapressuregradient。5）Thetemperatureandsalinityinlayer2areassumedtohavedepthdependence。Thevelocitywithinlayer2isassumedconstant.Theinitialthicknessoflayerischosensothatafterthehurricanepassage,h2≈h16)Verticaldensitygradientsinlayer2and3areheldconstantsincethestretchingissmall現(xiàn)在是10頁\一共有30頁\編輯于星期六b.BudgetsLayerthickness:EntrainmentvelocityWe≥0

HeatandsaltbalanceintheML:TheheatfluxQ=Qs+QL+Risthesumofsensible,latentandradiativeHeatexchangeacrosstheseasurfaceFisthemassflux,equaltoevaporationminusprecipitationThetermδTWeiscalledtheentrainmentheatfluxandisthebulkRepresentationoftheturbulentheatflux

現(xiàn)在是11頁\一共有30頁\編輯于星期六HeatandsaltbalanceintheML:isunderstoodtobeverticalgradientofTwithinlayer2Momentumbalancesforthelayers:WherefistheCoriolisparametertimestheverticalunitvector,τiswindstress,Pisthehydrostaticpressureperturbation現(xiàn)在是12頁\一共有30頁\編輯于星期六Thepressuregradients:ThehorizontaldensitygradientintheML:Andinthelowerlayers

現(xiàn)在是13頁\一共有30頁\編輯于星期六C.Turbulent-fluxparameterizationsSensibleheatfluxLatentheatfluxDensityofairdividedbydensityofseawaterBulktransfercoefficient,=1.3*10-3Windspeedat10mheightBheatcapacityofairdividedbyheatcapacityofseaweaterq10,ssspecifichumidityat10mheight,andattheseasurfaceassumingsatuationattheseasurfacetemperatureKlatentheatofvaporationdividedbytheheatcapacityofseawaterC.Turbulent-fluxparameterizations現(xiàn)在是14頁\一共有30頁\編輯于星期六C.Turbulent-fluxparameterizationsWindstress:Wherethedragcoefficient0,ifRv>1,IfRv≤1isabulkRichardsonnumberParameterizeentrainment現(xiàn)在是15頁\一共有30頁\編輯于星期六Fig9Schematicplanviewofthenumericalmodeld.Implementation現(xiàn)在是16頁\一共有30頁\編輯于星期六Thetimestep△t=△x/mUH,WheremisthesmallestIntegerthatgives△t≤2*103sTheoceanismoveddownthegridonerowaftereverymstepsandthefirstrowofthegridpointsisupdatedwiththeoceaninitialcondition.Spacederivativeareestimatedwithasecond-ordercenteredForm,andtime-steppingiscarriedoutusingthethree-time-level,two-step,leapfrogtrapezoidalmethod.

現(xiàn)在是17頁\一共有30頁\編輯于星期六Fig10Upwellingcomputedbythenumericalmodel(leftside)andGeisler’sanalyticalsolution(rightside)AcheckoftheentrainmentcalculationsComparingwiththequasi-steadyentrainmentWheren=1/2foralinearlystraitifiedfluid,andn=1foratwo-layerstratifiedfluid,WhereRτ=(ghδρ)/(p0τ)istheexternalRichardsonNumber。現(xiàn)在是18頁\一共有30頁\編輯于星期六Table4EB-10/EloiseoceaninitialconditionSpecificationontheEB-10/Eloisecasea.Oceaninitialconditionb.ModelhurricaneFig12Radialandtangentialwind-speedradialprofilecomputedfromtheEB-10winddata(points),andthemodelofthehurricaneusedinthesimulationoftheEB-10/Eloise(Solidline)現(xiàn)在是19頁\一共有30頁\編輯于星期六Fig13.MLtransportV1h1computedfromthedirectlyobservedwindsofEloise(solidline)andfromthemodelhurricane(dashedline)theMLtransportscomputedfromalocalmomentumbalance:現(xiàn)在是20頁\一共有30頁\編輯于星期六Fig15Planviewofthemodel-predictedycomponentofMLvelocity&TheSSTresponseshownasthechangeinseasurfacetemperaturefromtheinitialconditionRightwardbiasFig16Aschematicthatshowstherotationofawind-stressvector&thecosineoftheanglebetweenthewindstressandtheMLvelocity(ameasureofhowefficientlythewindstressisworkingtoincreasetheMLkineticenergy)5.Overviewoftheresponse現(xiàn)在是21頁\一共有30頁\編輯于星期六b.HorizontaladvectionofSSTFig15bTheSSTresponseshownasthechangeinseasurfacetemperatureFig23aObservedandpredictedseasurfacetemperaturefortheEB-10/EloiseReason:they-componentofvelocityintheMLcombinedwiththestrongy-gradientsin△C.Upwelling,pressuregradientsandvelocityresponseintheinteriorFig18bPumping&Fig19bUpwellingbelowthebaseoftheML現(xiàn)在是22頁\一共有30頁\編輯于星期六Twodynamicalconsequencesoftheupwelling1)ThefirsthalfoftheupwellingcycleisupwardandthustendstocausetheMLthicknesstodecrease.2)Upwellingsetsupatime-dependentpressuregradientwhichcouplestheMLwiththeinteriorandcausestheMLvelocitytorotate~5%fasterthanthatinafreeinertialmotiond.ThesubsurfaceresponseoftemperatureFig21Predictedsubsurfacetemperatureresponseshownasacross-tracksectionfortheEB-10Eloisecase&Initial(solid)andfinal(dashed)temperatureprofilesaty=-100,0,+100km現(xiàn)在是23頁\一共有30頁\編輯于星期六6.ComparisonofthemodelsolutionwiththeEB-10dataa.UpwellingFig22Observed(solid)andpredicted(dashed)upwellingbelowthebaseoftheMLduringtheEB-10/EloiseeventT(t)isthecorrectedtemperature,T0istheinitialtime-averagedtemperature,Islocaltemperaturegradient現(xiàn)在是24頁\一共有30頁\編輯于星期六b.SeasurfacetemperatureFig23Observed(solid)andpredicted(dashed)seasurfacetemperaturefortheEB-10/Eloiseevent&TheMLheatbalanceforthesimulationoftheEB-10/Eloiseeventb.SeasurfacetemperatureAlongthetrack,thenetair-seaexchangeis0.2*102℃m(~2Kcalcm-2);thenetentrainmentheatfluxis1.3*102℃m(~13Kcalcm-2),or~85%ofthetotalirreversiblefluxintotheML.EntrainmentisimportantintheMLmomentumbalance.Becauselayer2isquiescentduringtheentrainmentprocess,entrainmentactstoincreasetheMLthicknessanddecreaseVl.TheincreaseinMLdepthbyentrainmentiscrucialindeterminingthemaximumMLvelocity.CQisdifficulttoinferfromsimulationsbecausetheair-seaexchangeissmall.AconstantdragcoefficientCD=1.5*10-3givesgreatlyreducedentrainmentandanSSTresponse~40%belowthatobserved.現(xiàn)在是25頁\一共有30頁\編輯于星期六b.SeasurfacetemperatureAlongthetrack,thenetair-seaexchangeis0.2*102℃m(~2Kcalcm-2);thenetentrainmentheatfluxis1.3*102℃m(~13Kcalcm-2),or~85%ofthetotalirreversiblefluxintotheML.EntrainmentisimportantintheMLmomentumbalance.Becauselayer2isquiescentduringtheentrainmentprocess,entrainmentactstoincreasetheMLthicknessanddecreaseVl.TheincreaseinMLdepthbyentrainmentiscrucialindeterminingthemaximumMLvelocity.CQisdifficulttoinferfromsimulationsbecausetheair-seaexchangeissmall.AconstantdragcoefficientCD=1.5*10-3givesgreatlyreducedentrainmentandanSSTresponse~40%belowthatobserved.現(xiàn)在是26頁\一共有30頁\編輯于星期六Numericalexperimentsa.ParametricdependenceHurricane:strengthU10max,translationspeedandsize(theradiusatwhichthewindspeedeaquals1/2U10max)Ocean:initialMLdepth,thetempera