AS5537_final.docx

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1、SAsAerospaceaerospaceAnSAEInternationalGroupSTANDARDSAEAS5537REV.AIssued2004-05ReViSSdPrOoOSedDraft2013-04-05SuoersedinaAS5537WeatherSupporttoDeicingDecisionMaking(WSDDM)WinterWeatherNowcastingSystemRATIONALETheoriginalmotivationfortheWSDDMSystemwasoriginallydevelopedtoprovideflightlinedeicingoperat

2、orsthemostup-to-dateandrelevantweatherinformationonwhichtobasetheirdeicingdecisions.Thesystemhasalsobeenhighlyusefultoairportauthoritiesforsnowcrewmanagementofrunway,taxiway,androad-plowingactivities,aswellasandaircarriersforgroundde/anti-icingoperations,departurescheduling,andregionalairtrafficfaci

3、litiesforwinterweatherairtrafficoperations.Akeyelementofthesystemistheuseofoneormoreprecisionsnowgauges,whichprovidereal-timeestimatesoftheliquidequivalentsnowfallrateeveryminute.Thismeasurementisessentialtodeicingoperationsduetothedeterminationbythedeicingcommunitythattheliquidequivalentsnowfallrat

4、eisthekeyfactorleadingtothefailureofdeicing/anti-icingfluids.CurrentNationalWeatherSurfaceMETARstationsdonotprovideliquidequivalentsnowfallrates,butratherhourlysnowintensityestimatesbasedonvisibility.Snowintensityestimatesbasedonvisibilityhavebeenshowntobemisleadingwhenwetsnow,heavilyrimedsnow(snowt

5、hathasaccretedsignificantamountsofliquidclouddroplets),andsnowcontainingsinglecrystalsofcompactshape(nearlyspherical)occur.Researchershavedefinedthishazardashigh-VisibiIityZhigh-SnowfaIIrateconditions.Examinationoffiveofthemajoraircraftgrounddeicingaccidentshasshownthathighvisibility-highsnowfallrat

6、econditionswerepresentduringanumberoftheseaccidents.Alloftheaccidentshadnearlythesameliquidequivalentrateof2.5mm/hour(0.1inch/hour),butwidelyvaryingvisibilities.TheWSDDMSystemwasdesignedtodirectlyaddressthisconcernbyincludingsnowgaugesthatmeasureliquidequivalentsnowfallrateeveryminuteasoneofitscorec

7、omponents.AnotherimportantcomponentoftheWSDDMSystemisthe1-hournowcastofsnowfallratebasedonacombinationofradarreflectivityandprecipitationgaugedata.Thesenowcastsaredeterminedbyapplyingacalibrationfactortothereflectivitybasedonactualratesfromthegaugesandthentrackingthemovementofthereflectivity.Additio

8、nalfeaturesoftheWSDDMSystemincludes:(1)real-timeradarreflectivityfromWSR-88Dradarsdepictingcurrentlocationsofprecipitation,(2)meteorologicaldataattheairportandtwoormoresitesupto80km(-50miles)awayfromtheairportupdatedeveryminuteanddisplayedintextandgraphical(timeline)form,withthetimelinegoingbackamin

9、imumof2hours,(3)aone-hournowcastofradarreflectivitybasedontheuseofacrosscorrelationtechniqueoftheradarreflectivitydataupdatedeverysixtotenminutes,and(4)adepictionofthecurrentweatherconditionsfromNationalWeatherServiceMETARhourlyreportsorspecialreportsintextformatandalsodepictedgraphicallywithintheWS

10、DDMradardisplay.FOREWORDThisSAEAerospaceStandard(AS)recommendssettingguidelinesforthedeploymentoftheWeatherSupporttoDeicingDecisionMaking(WSDDM)winterweathernowcastingsystematsite-specificairports.Theyareintendedtoprovide(1)therelevantinformationtolocate,operate,andmaintainsuchsystemsand(2)hardwares

11、pecificationsfortheequipmentrequiredtobuildandoperatesuchsystems.SAETechnicalStandardsBoardRulesprovidethat:ThisreportispublishedbySAEtoadvancethestateoftechnicalandengineeringsciences.Theuseofthisreportisentirelyvoluntary,anditsapplicabilityandsuitabilityforanyparticularuse,includinganypatentinfrin

12、gementarisingtherefrom,isthesoleresponsibilityoftheuser.SAEreviewseachtechnicalreportatleasteveryfiveyearsatwhichtimeitmayberevised,reaffirmed,stabilized,orcancelled.SAEinvitesyourwrittencommentsandsuggestions.Copyright2013SAEInternationalSAE values your input. To provide feedback on this Technical

13、Report, please visit http:/www.sae.ora/technical/standards/PRODCODEAllrightsreserved.Nopartofthispublicationmaybereproduced,storedinaretrievalsystemortransmitted,inanyformorbyanymeans,electronic,mechanical,photocopying,recording,orotherwise,withoutthepriorwrittenpermissionofSAE.TOPLACEADOCUMENTORDER

14、:Tel:877-606-7323(insideUSAandCanada)Tel:+1724-776-4970(outsideUSA)Fax:724-776-0790Email:CustomerServicesae.orgSAEWEBADDRESS:httpJ/www.sae.orgIngeneral,theWSDDMSystemisanautomatedsystemthatproducesreal-timeanalysesandshort-termnowcastsofwinterweatherconditionsintheairportterminalarea.Thedatausedbyth

15、esystemareprovidedfromprecipitationgauges,weatherradars,surfaceweatherstations,andNationalWeatherServiceAviationRoutineWeatherReport(METAR)datageneratedfromAutomatedSurfaceObservingSystems(ASOS).ThesedataareprocessedbytheWSDDMsoftwaretoproducegraphicalandtextualdepictionsofthecurrentweathercondition

16、s.Aone-hourforecastofexpectedprecipitationratesattheairportisalsoproducedandupdatedeverysixtotenminutes,dependingonthefrequencyofnewdatareceivedfromtheweatherradars.Theresultinganalysesandforecastsaredisplayedviaawebpageorondedicatedcomputersystemsinauser-friendlyformatthatiseasilyunderstoodbynon-meteorologists.DetailsregardingthegraphicaldisplayandthecomputeralgorithmsusedtogeneratethedisplayaregivenintheWSDDMarticleintheBulletinoft