DOC

VERIFICATION OF TYPHOON FORECASTS BY THE GRAPES MODEL

By Billy Morgan,2014-02-19 07:28
10 views 0
VERIFICATION OF TYPHOON FORECASTS BY THE GRAPES MODELOF,BY,of,THE,MODEL,model,the,The,Model

    VERIFICATION OF TYPHOON

    FORECASTS BY THE GRAPES MODEL

    vo1.16No.1JoURNALoFTRoPICALMETEoRoLoGYMarch2009

    ArticleID:10068775(2010)0107705

    VERIFICATIoNoFTYPHooNFoRECASTSBYTHEGRAPESMoDEL

    SONGYv(T-),YEChengzhi(叶成志),HuangZhen(黄振),PUWen-yao

    (濮文耀)

    (1.DalianMeteorologicalObservatory,Dalian116001China;2.HunanMeteorologicalObservatory,

    Changsha410007China;3.DalianWeatherModificationOffice,Dalian116001China) Abstract:Fourlandfallingtyphooncasesin2005wereselectedforanumericalsimulationstudywiththe

    Global/RegionalAssimilationandPredictionSystem(Grit,ES)mode1.Thepreliminaryassessment

    resultsoftheperformanceofthemode1.includingthepredictionsoftyphoontrack.1andfalltime.1ocation

    andintensity.etc..arepresentedandthesourcesoferrorsareanalyzed.The24

    hourdistanceforecasterror

    ofthetyphooncenterbythemodelisshowntobeabout131km.whilethe48.hourerroris252km.The

    modelwasrelativelymoreskilfulatforecastsoflandfalltimeandlocationsthanthoseofintensityat

    landfal1.Onaverage.the24.hourforecastswereslightlybetterthanthe48

    hourones.Ananalysisofdata

    impactsindicatesthattheassimilationofunconventiona1observationdataisessentialfortheimprovement

    ofthemodelsimulation.Themodelcouldalsobeimprovedbyincreasingmodelresolutiontos

imulatethe

    mesoscaleandfinescalesystemsandbyimprovingmethodsofterrainrefinementprocessing.

    Keywords:GRAPESmodel;landfallingtyphoon;verification CLCnumber:P444Documentcode:Adoi:10.3969/j.issn.10068775.2010.01.011 1INTRoDUCTIoN

    Landfalls0ftyphoonsin2005were

    characterizedbylargenumbers,strongwinds, torrentialrainfa11,anddisasterssuchasfloods, landslides,andmudflows,whichclaimedhuman livesandcausedhugefinanciatandecologicaI losses.Statisticsshowthat91.4985millionpeople wereaffected,amongthesewereincluded244dead and57missing.InChina,thedirectlossesreached RMB75.7billion,withtheprovincesofZhejiang. Fujian,andAnhuirankingatthetopofthelosslist. Amongthelandfallingtyphoons,Haitang,Matsa, TalimandKhanun]werethemostintenseand causedseveredamage[11

    ItiSthereforeofgreatimportancetobeableto accuratelypredictthelandfa11ofatyphoon. Knowingthetrackofthetyphoon,inparticular.is crucialfordisasterpreventionandmitigation. Theperformancesoftrackforecastingfor landfallingtyphoonsintheNorthwestPacificand theSouthChinaSeaindifferentcountriesimproved in2005:forexample,the24hand48hforecast

    errorsoftyphoonpathsissuedbytheCentral MeteorologicalObservatoryofChinawere120km and198km.respectively.ThoseoftheJoint TyphoonWarningCenteroftheUSwere1l0kmand

    187kmj,respectively.ThecorrespOndingerrors were10lkmandl76kmforJapanLjand94kmand 170kmforTaiwan.ChinaLJ.However.the

    forecastingski11fortyphoonintensityhasshownno similarimprovement.asstudyontheimpactofthe structureoftropicalcyclonesonthechangein intensityhasbeenlimited[5-o1.

    ThemodelGRAPESbeganitsexperimenta1

    operationattheNationalMeteorologicalCenterof Chinaduringtherainyseasonof2005andhas providedgoodguidancefortheforecastersat dif-ferentoperationallevelsnationwide.With GRAPES.themostpowerfultyphoonsof2005. Haitang,Matsa,TalimandKhanum,weresimulated inthisstudytoassesstheforecastsoftrack.1andfall locationandtime.andintensityin24hand48hand toanalyzetheerror.

    2THEMoDELGRAPES

    Receiveddate:2009-?05?-08;reviseddate:2009..11-12 Foundationitem:KeyScienceProjectforHunanMeteorologicalBureau(200602;200705)

    Biography:SONGYv,seniorengineer,mainlyundertakingtheresearchonmarinemeteorolo

    gy

    Emailforcorre~ondenceauthor:songyu_ll@163.com

JournalofTropicalMeteorologyV01.16

    The1imited.areamodelGRAPESadoptsa

    semi-implicit,semiLagrangetimeadvectionanda

    terrainfollowingtopographydependentcoordinates.

    ThesemiLagrangetraceiscalculatedwiththe

    trajectoriesofathreedimensiona1vectorparticle. Horizontalresolutionis30kmand31layersinthe vertical,withoutBogusfortheTCs.Thedataof surface,sounding,andboatareused,butwithno satelliteorradardata.Themodel,coveringthe regionofEastAsia.hasatimeintervalof300sand

    physics,andadoptsthe usessimpleicemicro

    Kain.Fritschconvectionscheme,Dudhiashortwave andRRTMlongwaveradiationschemes,andslab schemes.TheoutputsofT213L3at2000areusedas

    theinitialfieldsandboundarylayercondition. Theaverage24hand48herrorsarel31km

    and252km,respectively,whicharedetermined basedon25sampleforecastsfor24hand22for 48h.ThetrackforecastedforHaitangwasthemost stable,witherrorsof32.7kmfor24hand64.7km for48h,whilethatforMatsawastheworst,with errorsOf80.8kmandl64.8km.respectively.The averageerrorsofallfourtyphoonswere58.4kmin 24hand123kmin48h.

    3VERIFICATIoNANDANALYSISOF

    TCTRACKFoRECAST

    3.1Zeri~cationofHaitang

    Atotalofsevenforecastsimulationsweremade ofthelifecycleofHaitangfromcyclogenesisto decayexceptfortheinitialandendingstages(See Fig.1a,.A11oftheerrorsforthe24.hforecastof theeye1ocationarewithinarangeof150kmwith themostwithin100kmandanaverageerrorofonly

77km;themeanerrorforthe48hforecastis151

    km.Itturnsoutthatthemodelisquiteskillfulin predictingthetrackofTyphoonHaitang. 3.2VerificationofMatsa

    LikethecaseofHaitang,therearealsoseven forecastsimulationsforthewholelifecycleOf Matsa,excludingtheinitialandendingstages(See Fig.1b1.Fortheforecastofthetyphooneye,the 24herrorsarebetween100kmand300kmwith theaverageashighas205km,mainlyduetothe relativelylargedeviationsinthelandfalland recurvatureforecastsofMatsa.The48hforecast

    errorsofthetyphooncenterarealsoquitelarge.al1 surpassing1O0kmandwithanaverageof353km. 3.3Ver/ficationofTalim

    Fiveforecastsofallbuttheinitialandending stagesofTyphoonTalimweremade,coveringits entireprocessfromformationtodissipation(SeeFig. 1c,.The24herrorsareallwithin200kmasfaras theforecastsofeyepositionareconcernedwiththe averageerrorat111km;themeanerrorfallson246 kminthe48hforecast.

    3.4VerificationofKhanum

    Asmanyass1xforecastsimulationswere conductedforKhanum,coveringallbuttheinitial andendingstagesofthetyphoon(SeeFig.1.The errorsofthe24hforecastofthestormeyeare

    mostlysmallerthan200km,averagingat132km. Mostofthe48hforecasterrorsarelargerthan200 km,averagingat261km.

3.5Comprehensiveanalysis

    Relativelyspeaking,thetrackforecastsofthe centersofHaitangandKhanumareveryclosetothe observation.orevenoverlapwithit.The24.htrack forecastsofMatsaandTalimaregenerallyparallel withtheobservation.ForMatsa.theforecastofthe recurvatureafterlandfa11isnotgoodandthe forecastsofthecyclogenesisanddissipatingstages deviatesomuchthattheyarealmostinapplicable. Comparedwiththe24htrackforecast.the48hone

    decreasessomewhatinaccuracy,

    maintainingaconsistenttendencywiththat observation.

    though

    ofthe

    Basedonthestatisticsofthe25casesofthe 24.hforecastand22casesofthe48hforecast,the

    meanerrorisshowntobel31kmfor24hand252 kmfor48hfSeeFig.1e1.Haitangisthebest forecastedintermsofitseyepositionwiththe24h

    errorat77kmandthe48hforecasterroratl51km;

    themovementforecasthasthehighestapplicability. Asshownintherootmeansquareerror(RMSE)of thecentersoftheseTCs.theforecastisthemost stableforHaitang,being32.7kmand64.7kmfor 24hand48hrespectively;theRMSEisthelargest fortheforecastofMatsa.being80.8kmand164.8 kmfor24hand48h,respectively.Theaverage RMSEsofthefourTCsare58.4kmfor24hand 123kmfor48h.respectively(SeeFig.1D.

4ACCESSINGTHELANDFALL

    Thelandfa11fclrecast

    Chinawasrelativelylater,

    forHaitanginTaiwan,

    northoftheactua1site,

    andweaker.TheforecastshowedthatTalimwas passingnorthtoTaiwanandalsoweaker(Table1). ThemodelforecastwasgoodforHaitang,Talim andKhanumlandinginFujianandZhejiang.bothin timeandlocation.whiletheintensitieswereweaker forTalimandKhanum(Table21.Theerrorin landfallsiteforMatsawasabout100km. No.1SONGYv(宋煜),YEChengzhi(叶成志)etal79

    Afterinitialfieldanalysis,wefoundthatthese fieldswerealsoweakerthanreality(Table3). t00

    耋曩0

    0?

    ?

    埔?

    -?

    ?

    0?

    

    I"11IO0

    H

    0??

    l?

    --

Ill

    H

    ?Ill

    III- ..1伯???ilit0??曲?

    tiIIle C

    .'^一一on—— '.,---I ?

    ':,.

    

    _r''

    ilOIiOOi?埔?n?0

    time

    ?n?

    niOOO eGO

    

    0MO

    I?

    .?:

    lot

    H

    

    -"ltll

    ?

    

T?"ii??一1U^?一

    ,,.

    Ilk,

    k一一一?,!.?.

    T'1.r0

    l?1.?'?-?:o?I?,?

    time

    d

    ''''?nI/

    ..?

    '

    \.J/

    '\r

    ...?.

    ?Hl??

    time

    f

    Fig.1ForecasterrorsforTClocations.A:Haitang;b:Matsa;c:Talim;d:Khanum;e:averageer

    rors;RMSE

    Table1ComparisonoftheforecastsofHaitangandTalimforlandfallonTaiwanIsland.

    typhoonValidtimeLandingtimeLandingsiteMin.pressureMax.winds

    Observedlandfall0600Sept.1nearHualian,TaiwanIs.930hPa50m/s

    Forecastat0800Aug.312300Aug.31 j.ffnh.ip.f

    lalwanIs.

    Biasinf0recast7hearlierthan1latitudenorthwardthan observationobservation

    <982.5hPa22.5m/s

    40hPaweaker27.5m/sweaker

    5CoNCLUSIoNSANDDISCUSSIONS

    AnalysisonthetracksandlandfallsOfthemost severetyphoonsin2005indicates:

    f1)Exceptfortheinitialandendingstagesin whichthecenterlocationerrorsin24hand48h were13lkmand252km.themodelwasstable.and thepredictedtracksbasicallyparalleledthe observedtrackswithahighcredibilityofreference. (2)Themodeloutputsoftyphoonlandfall

    agreedwellwithrealityinthesoutheastChinaarea. especiallywithrespecttolandfalltimeandlocation. Theforecastedlandfalllocationof24hwasbetterthan thatof48h.

    f31Thelocationerrorsattheinitialandending stageswereobviousandtheforecastsshoweda 0一一0^h)

    _--

    o3

    哺凸曲^^o

    80JournalofTropicalMeteorologyVO1.16 weakeningtendency.TheblockageofTaiwanIsland isworthmentioning,asthemodeltendedtopredict theTCspassingthenortherntipoftheisland.Thus, thetopographicprocessingfortheislandshouldbe improved.

    Table2ComparisonofforecastsofHaitang,Matsa,TalimandKhanumforlandfallonmainlan

    dChina.

    Table3Comparisonofinitialvaluesofthemodel

    U

    0

Report this document

For any questions or suggestions please email
cust-service@docsford.com