AS5537_final.docx

SAsAerospaceaerospaceAnSAEInternationalGroupSTANDARDSAEAS5537REV.AIssued2004-05ReViSSdPrOoOSedDraft2013-04-05SuoersedinaAS5537WeatherSupporttoDeicingDecisionMaking(WSDDM)WinterWeatherNowcastingSystemRATIONALETheoriginalmotivationfortheWSDDMSystemwasoriginallydevelopedtoprovideflightlinedeicingoperatorsthemostup-to-dateandrelevantweatherinformationonwhichtobasetheirdeicingdecisions.Thesystemhasalsobeenhighlyusefultoairportauthoritiesforsnowcrewmanagementofrunway,taxiway,androad-plowingactivities,aswellasandaircarriersforgroundde/anti-icingoperations,departurescheduling,andregionalairtrafficfacilitiesforwinterweatherairtrafficoperations.Akeyelementofthesystemistheuseofoneormoreprecisionsnowgauges,whichprovidereal-timeestimatesoftheliquidequivalentsnowfallrateeveryminute.Thismeasurementisessentialtodeicingoperationsduetothedeterminationbythedeicingcommunitythattheliquidequivalentsnowfallrateisthekeyfactorleadingtothefailureofdeicing/anti-icingfluids.CurrentNationalWeatherSurfaceMETARstationsdonotprovideliquidequivalentsnowfallrates,butratherhourlysnowintensityestimatesbasedonvisibility.Snowintensityestimatesbasedonvisibilityhavebeenshowntobemisleadingwhenwetsnow,heavilyrimedsnow(snowthathasaccretedsignificantamountsofliquidclouddroplets),andsnowcontainingsinglecrystalsofcompactshape(nearlyspherical)occur.Researchershavedefinedthishazardashigh-VisibiIityZhigh-SnowfaIIrateconditions.Examinationoffiveofthemajoraircraftgrounddeicingaccidentshasshownthathighvisibility-highsnowfallrateconditionswerepresentduringanumberoftheseaccidents.Alloftheaccidentshadnearlythesameliquidequivalentrateof2.5mm/hour(0.1inch/hour),butwidelyvaryingvisibilities.TheWSDDMSystemwasdesignedtodirectlyaddressthisconcernbyincludingsnowgaugesthatmeasureliquidequivalentsnowfallrateeveryminuteasoneofitscorecomponents.AnotherimportantcomponentoftheWSDDMSystemisthe1-hournowcastofsnowfallratebasedonacombinationofradarreflectivityandprecipitationgaugedata.Thesenowcastsaredeterminedbyapplyingacalibrationfactortothereflectivitybasedonactualratesfromthegaugesandthentrackingthemovementofthereflectivity.AdditionalfeaturesoftheWSDDMSystemincludes:(1)real-timeradarreflectivityfromWSR-88Dradarsdepictingcurrentlocationsofprecipitation,(2)meteorologicaldataattheairportandtwoormoresitesupto80km(-50miles)awayfromtheairportupdatedeveryminuteanddisplayedintextandgraphical(timeline)form,withthetimelinegoingbackaminimumof2hours,(3)aone-hournowcastofradarreflectivitybasedontheuseofacrosscorrelationtechniqueoftheradarreflectivitydataupdatedeverysixtotenminutes,and(4)adepictionofthecurrentweatherconditionsfromNationalWeatherServiceMETARhourlyreportsorspecialreportsintextformatandalsodepictedgraphicallywithintheWSDDMradardisplay.FOREWORDThisSAEAerospaceStandard(AS)recommendssettingguidelinesforthedeploymentoftheWeatherSupporttoDeicingDecisionMaking(WSDDM)winterweathernowcastingsystematsite-specificairports.Theyareintendedtoprovide(1)therelevantinformationtolocate,operate,andmaintainsuchsystemsand(2)hardwarespecificationsfortheequipmentrequiredtobuildandoperatesuchsystems.SAETechnicalStandardsBoardRulesprovidethat:ThisreportispublishedbySAEtoadvancethestateoftechnicalandengineeringsciences.Theuseofthisreportisentirelyvoluntary,anditsapplicabilityandsuitabilityforanyparticularuse,includinganypatentinfringementarisingtherefrom,isthesoleresponsibilityoftheuser."SAEreviewseachtechnicalreportatleasteveryfiveyearsatwhichtimeitmayberevised,reaffirmed,stabilized,orcancelled.SAEinvitesyourwrittencommentsandsuggestions.Copyright©2013SAEInternationalSAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.ora/technical/standards/PRODCODEAllrightsreserved.Nopartofthispublicationmaybereproduced,storedinaretrievalsystemortransmitted,inanyformorbyanymeans,electronic,mechanical,photocopying,recording,orotherwise,withoutthepriorwrittenpermissionofSAE.TOPLACEADOCUMENTORDER:Tel:877-606-7323(insideUSAandCanada)Tel:+1724-776-4970(outsideUSA)Fax:724-776-0790Email:CustomerServicesae.orgSAEWEBADDRESS:httpJ/www.sae.orgIngeneral,theWSDDMSystemisanautomatedsystemthatproducesreal-timeanalysesandshort-termnowcastsofwinterweatherconditionsintheairportterminalarea.Thedatausedbythesystemareprovidedfromprecipitationgauges,weatherradars,surfaceweatherstations,andNationalWeatherServiceAviationRoutineWeatherReport(METAR)datageneratedfromAutomatedSurfaceObservingSystems(ASOS).ThesedataareprocessedbytheWSDDMsoftwaretoproducegraphicalandtextualdepictionsofthecurrentweatherconditions.Aone-hourforecastofexpectedprecipitationratesattheairportisalsoproducedandupdatedeverysixtotenminutes,dependingonthefrequencyofnewdatareceivedfromtheweatherradars.Theresultinganalysesandforecastsaredisplayedviaawebpageorondedicatedcomputersystemsinauser-friendlyformatthatiseasilyunderstoodbynon-meteorologists.DetailsregardingthegraphicaldisplayandthecomputeralgorithmsusedtogeneratethedisplayaregivenintheWSDDMarticleintheBulletinoftheAmericanMeteorologicalSocietyasreferencedin2.2ofthisdocument.APDFfileofthisarticlecanbefoundatthefollowingwebsite:http:/www.ral.ucar.edu/projects/wsddm/bams.pdf.TABLEOFCONTENTS1. SCOPE41.1 Purpose41.2 Motivation41.3 Units41.4 Safety42. APPLICABLEDOCUMENTS42.1 ISOPublications42.2 OtherRelatedPublications43. WSDDMSYSTEMDESCRIPTION53.1 WSDDMSystemTypes53.2 All-WeatherGaugeConfigurationsforWSDDMSystems:63.3 KeyWSDDMComponents:94. ALL-WEATHERGAUGERECOMMENDATIONS:104.1 SingleAlterWindShield:114.2 BelfortDoubleAlterWindShield:115. WEATHERSENSORRECOMMENDATIONS:116. DATALOGGERRECOMMENDATION:117. RADIOMODEMRECOMMENDATION:118. ALL-WEATHERGAUGESANDWEATHERSENSORSITING:129. CALIBRATIONMETHODS:1210. MAINTENANCE：1211. COMPUTERANDOPERATINGSYSTEMRECOMMENDATION:1211.1 CentralProcessingComputer:1211.2 UserDisplayComputer:1211.3 Web-BasedWSDDMDisplay:1212. NOTES:1312.1 KeyWords:13TABLEOFFIGURESFigure 1 -NCARWSDDMdisplay6Figure 2 -VaisalaAviCastWSDDMdisplay6Figure 3 -WSDDMsystemwithfoursurfaceweatherstations8Figure 4 -WSDDMsystemwithtwosurfaceweatherstations8Figure 5 -WSDDMsystemwithonesurfaceweatherstation9Figure 6 -TopViewoftheHotplate(PanelonLeft),andBottomView(PanelontheRight)10Figure 7 -SingleAlterWindShield11Figure 8 -BelfortDoubleAlterWindShield111. SCOPE1.1 PurposeThepurposeofthisSAEAerospaceStandard(AS)istoprovideguidelinesforthecomponentsandconfigurationsthatdefinetheresearchandcommercialversionsoftheWeatherSupporttoDeicingDecisionMaking(WSDDM)winterweathernowcastingsystem.1.2 MotivationDeicing/anti-icingendurancetimedatapresentedtotheSAEG-12HoldoverTimeSubcommitteebytestinglaboratoriesforexaminationandvalidationhaveclearlyshownthattheliquidequivalentsnowfallrateisthemostimportantfactorindeterminingtheendurancetimeofadeicing/anti-icingfluid.However,currentNationalWeatherServicesurfacestationsdonotprovideliquidequivalentsnowfallrates,butratherhourlysnowintensityestimatesbasedonvisibility.Snowintensityestimatesbasedonvisibilityhavebeenshowntobemisleadingwhenwetsnow,heavilyrimedsnow(snowthathasaccretedsignificantamountsofclouddroplets),andsnowcontainingsinglecrystalsofcompactshape(nearlyspherical)occur.Undertheseconditions,visibilitycanbejudgedtobehighduetotherelativelysmallsize(crosssectionalarea)ofthesetypesofcrystals,leadingtoestimatesoflightsnowfallintensitywheninfacttheactualsnowfallrateinliquidequivalenttermsismoderatetoheavy.Researchersdefinethehazardashigh-visibility,high-snowfallrateconditions.Researchersexaminedfiveofthemajorgrounddeicingaccidentsandshowedthathigh-visibility,high-snowfallrateconditionswerepresentduringmanyoftheseaccidents.Alloftheaccidentshadnearlythesameliquidequivalentrateof2.5mmhor(0.1inch/hour),butwidelyvaryingvisibilities.TheWSDDMsystemwasdesignedtodirectlyaddressthisconcernbyincludingsnowgaugesthatmeasuresnowfallrateeveryminuteasoneofthesystemscorecomponents.AsecondmotivationinthedesignoftheWSDDMSystemwastoprovideairlinesandairportauthoritieswithreal-timeaccurateweatherinformationthatcanbeusedtoimprovedecision-makingregardingaircraftgrounddeicing/anti-icingoperationsandairfieldsnowcrewmanagement1.3 UnitsThevaluesstatedinSIunitsaretoberegardedasthestandard.1.4 SafetyWhilethematerials,methods,applications,andprocessesdescribedorreferencedinthisdocumentmayinvolvetheuseofhazardousmaterials,thisdocumentdoesnotaddressthehazardsthatmaybeinvolvedinsuchuse.Itisthesoleresponsibilityoftheusertoensurefamiliaritywiththesafeandproperuseofanyhazardousmaterialsandprocessesandtotakethenecessaryprecautionarymeasurestoensurethehealthandsafetyofallpersonnelinvolved.2. APPLICABLEDOCUMENTSThefollowingpublicationsformapartofthisdocumenttotheextentspecifiedherein.ThelatestissueofSAEpublicationsshallapply.Theapplicableissueofotherpublicationsshallbetheissueineffectonthedateofthepurchaseorder.Intheeventofconflictbetweenthetextofthisdocumentandreferencescitedherein,thetextofthisdocumenttakesprecedence.Nothinginthisdocument,however,supersedesapplicablelawsandregulationsunlessaspecificexemptionhasbeenobtained.2.1 ISOPublicationsAvailablefromInternationalOrganizationforStandardization,CasePostale56,rueVarembe,CH-1211,Switzerland.ISO10012QualityAssuranceRequirementsforMeasuringEquipment2.2 OtherRelatedPublicationsWeatherSupporttoDeicingDecisionMaking(WSDDM):AWinterWeatherNowcastingSystem.R.M.Rasmussen,M.Dixon,F.Hage,J.Cole1C.Wade,J.Tuttle,S.McGettigan5T.Carty,L.Stevenson,W.Fellner,S.Knight,E.Karplus,andN.Rehak1BulletinoftheAmericanMeteorologicalSociety,82,579-595.CommonSnowfallConditionsAssociatedwithAircraftTakeoffAccidents,2000:R.M.Rasmussen,J.Cole,K.R.K.Moore,andM.Kuperman,J.ofAircraft,37,110-116.TheEstimationofSnowfallRateUsingVisibility.1999:R.M.Rasmussen,J.Vivekanandan,J.Cole,B.Myers,andC.Masters:J.Appl.Met.,38,1542-1563.TheHotplatePrecipitationGauge,2008:R.M.Rasmussen,J.Hallett,R.Purcell,S.LandoltandJ.Cole,J.Atmos.OceanicTechnol.,28,148-164.ANewGroundDeicingHazardAssociatedwithFreezingDrizzleIngestionbyJetEnginesduringTaxi,2006:R.M.Rasmussen,C.Wade,R.K.Moore,A.Davis,B.Reis,T.LisiandA.Ramsay:JournalofAircraft,43,1448-1457.HowWellareweMeasuringSnow:TheNOAA/FAA/NCARWinterPrecipitationTestBed,2012:R.M.RasmussenandCoauthors:BulletinoftheAmericanMeteorologicalSociety,93,811-829.3. WSDDMSYSTEMDESCRIPTION3.1 WSDDMSystemTypesTherearetwotypesofWSDDMSystemscurrentlyinuse:theresearchversion(developedbyNCARandhereafterreferredtoastheNCARWSDDMSystem'*)andthecommercialversion(marketedbyVaisala,Inc,hereafterreferredtoasthewAviCastSystem").Bothsystemsutilizethesameunderlyingtechnologyanddata,butaregraphicallydifferentinappearance(Figures1and2).BothversionsofWSDDMconsistofatleastoneall-weathergauge,andadditionalgaugesaredependentonthenumberofsurfacestationsinstalledforagivenairport.Fortheprimaryairportsitelocation,itisrecommendedthegaugebeinstalledinalocationrelativelyclosetowherethegrounddeicingoperationsoccur.Datafromthesesurfacestationsaretypicallytransferredviacellularmodem,ethernetconnection,orsatellitemodem.RadiomodemsareusedasabackupbytheNCARWSDDMsystemintheeventofacellularmodemfailure.NationalWeatherServiceNexRADradardataandnear-vicinityMETARdataarealsoavailableforbothsystems.正g=stats!FIGURE 1 - NCAR WSDDM DISPLAY1-32:5:3:3:33:2 累一fia S OssxM: OTM»#snlls:*ltll wm1s*8<sBFIGURE 2 - VAISALA AVICAST WSDDM DISPLAY3.2 All-WeatherGaugeConfigurationsforWSDDMSystemsFortheprimarysurfaceWSDDMweatherstation,asingleall-weathergaugeoptionisthenormalconfigurationforaWSDDMweatherstationsystem(describedabove).Thisconfigurationdoesnotprovideanyupstreaminformationonapproachingsnowstorms.Toobtainamoreaccurateestimateofstormmotion,radar-estimatedprecipitationratesandforecastprecipitationrates,additionalsurfacestationsupstreamoftheairportarerecommended,specificallyupwindofthedirectionthatanairportpredominatelyexperiencessnowstorms.Theseadditionalgaugesmaybeplacedattheairportorothercriticalupstreamlocations(ie,otherairportslocatedupstream).TheselocationsmaybedefinedbytheuserortheWSDDMvendor(vendorshouldbeabletosupplyrecommendationsonwhereandhowmanyadditionalgaugestoinstall).Ifitisdecidedthatfouradditionalall-weathergaugesarerequiredtheyshouldbelocatedapproximately35km(22miles)east,west,north,andsouthoftheairporttoprovideanindicationofsnowonsetandintensityupstreamoftheairport(Figure3).Ifitisdecidedthattwoadditionalall-weathergaugesaresufficienttheyshouldbelocatedapproximately35km(22miles)upstreamoftheairportinthedirectionofthemostfrequentsnowstormtrackstoprovideanindicationofsnowonsetandintensityupstreamoftheairport(Figure4).Ifitisdecidedthatoneadditionalall-weathergaugeissufficient,thenitshouldbelocatedapproximately35km(22miles)upstreamoftheairportinthedirectionofmostfrequentstormtrackstoprovideanindicationofsnowonsetandintensityupstreamoftheairport(Figure5).DirectionofFIGURE3-WSDDMSYSTEMWITHFOURSURFACEWEATHERSTATIONS.FIGURE4-WSDDMSYSTEMWITHTWOSURFACEWEATHERSTATIONS.3.3 KeyWSDDMComponentsThekeyhardwarecomponentsareasfollows:1. All-weathergaugemeasuringliquidequivalentrateseveryminute.Theminimumnumberofgaugesshallbeinaccordancewiththedescriptioninsection3.2.SeeSection4forthegaugespecificationandSection8foradditionalsitingrequirements.2. Weatherstationsmeasuringtemperature,humidity,windspeedanddirectionateachofthegaugelocations.SeeSection5foradetailedspecificationoftheweathersensorsandSection8forsitingrequirements.3. Dataloggerateachgaugeandweatherstationsitetoingestthedatafromtheinstrument,time-stampthedata,performinitialdataprocessingandqualitycontrol,andtransmitthedatatoalocalcomputer.Section6providesadetailedspecificationofthedatalogger.4. RadiozcelluIarZsateIIitemodemsandEthernetconnectionsateachgauge/weatherstationsiteinordertotransmitthedatatoacentralcomputer.SeeSection7foradetailedspecificationofthemodems.5. Weatherstation,radarandMETARdatareceivingandprocessingcomputerwiththeLinuxoperatingsystem.See11.1foradetailedspecificationofthecomputerandoperatingsystem.SoftwaretooperatethesystemwillbeprovidedandinstalledbyaprivatevendorlicensedbyUniversityCorporationforAtmosphericResearch.6. OptionofeitheradedicatedUserDisplayComputerateachusersite(NCARWSDDMSystem)oraWebbasedWSDDMdisplay(AviCastSystem).See11.2foradescriptionofthededicatedUserDisplaycomputerandoperatingsystemand11.3foradescriptionoftheWeb-baseddisplaysystem.TheadvantageoftheWebbaseddisplaysystemislowercostandgreateraccessibilitytotheWSDDMSystembyalargernumberofusersandfromanylocationthatisWebaccessible.Advantageofthededicateduserdisplayisfasteraccesstothedata,greaterpan,zoom,andmovieloopingcapabilityandeasydisplayconfigurabilitytouserneeds.SoftwaretooperatethedisplaywillbeprovidedandinstalledbyaprivatevendorlicensedbyUCAR.4. ALL-WEATHERGAUGERECOMMENDATIONSTheWSDDMall-weathergaugeshallbeabletomeasureliquidequivalentsnowfallrateeve