AircraftandSatelliteDataforIcingVerification
The Use of Observations in the Transition of Research Aviation Weather Products into Operations
ArleneLaing1,KenFenton1,MattWandishin2,GearyLayne2,LauraPaulik2,,Soner Yorgun2,andMelissaPetty1
ForecastImpactandQualityAssessmentSection(FIQAS)
OffshorePrecipitationandOceanicConvection
FractionRelativeHumidity
Tempe
rature,°C
PIREPs:BackgroundPIREPsprovidevaluablein-situobservationsofweatherphenomena,suchasicingandturbulence.However,theyareinherentlysubjective.Thelocation(horizontalandvertical),timeandtheintensityofthereportedweatherphenomenonarebasedonaircrewinterpretation.
AMDARversusPIREPsAircraft (AMDAR)observationsofrelativehumiditywerecomparedtoicingPIREPsinordertoidentifythedistributionsoftemperatureandmoistureassociatedwithanicingevent.
SatelliteDataforIcingCloudSatandCALIPSOcloudclassificationverticalcross-sectionsareusedtoimplementicingverificationbecausetheyhelptodifferentiatemicrophysicalpropertiesanddeterminingicingpotential.
VerticallyIntegratedLiquid(VIL)derivedfromgroundradarwascomparedtoGPMsatellite-derivedVILtobetterunderstandagreementwheretheproductsoverlapanddeterminebiasesusefulinassessingtheOPC.
GroundRadarVIL(kg/m2)
GPMVIL(kg/m
2 )
Aircraft(AMDAR)RelativeHumidityMeasurements
PilotReports(PIREPs)
CloudSat/CALIPSOSatelliteExtent
GlobalPrecipitationMission(GPM)satellitedataandsurfacereports(METARs)wereinvestigatedpriortoassessingOPC,whichprovidesradar-likevariables,usedbyaviation,forareasoffshore.
GriddedIcingForecasttobeVerified
‘Relaxed’: IcingnotexpectedoutsidePurpleshading
‘Strict’: IcingLikelywithinPurpleshading
EddyDissipationRate(EDR)§ Aircraft-independentmeasureofatmosphericturbulence.§ EDRmeasurementsfromDeltaandUnitedAirlinesare
comparedtoPIREPs.
PIREPandEDRsMatchingforTurbulenceVerification
MatchingPIREPstoEDRs§ PIREPsarematchedtotheircorrespondingsetofEDRs
fromthesameaircraft.§ Differenttimewindows(aroundaPIREP)areusedto
matchthemaximumpeakEDRvaluetothePIREP.§ Jan2013– Jun2015periodisanalyzed.
MatchingSummary§ PIREPlocationerrors
showsensitivitytothechoiceoftimewindowformatching.
§ Locationerrorstatisticsfor±7.5minuteswindowagreewithpriorstudies.
§ StrongrelationshipexistsbetweenthePIREPreportlagandlocationerrors.
2
1
METARSandAMDARtoverifyCeilingandVisibility
Lightning,EchoTops,CloudTopHeight
Supportingtransitionof:OffshorePrecipitationCapability(OPC)andEnsembleProbabilisticOceanicConvectiveHazards (EPOCH)
SupportingCurrentandForecastIcingProducts(CIPandFIP)andIcingProduct-AlaskaForecasts(IPA-F)Transition
SupportingGraphicalTurbulenceGuidance:GTG-3,GTGNowcast(GTG-N),GTG-GlobalTransition
InsupportofthetransitionofnewAWCCeilingandVisibilityproducts
AcknowledgementsThisresearchisinresponsetorequirementsandfundingbytheFederalAviationAdministration(FAA). TheviewsexpressedarethoseoftheauthorsanddonotnecessarilyrepresenttheofficialpolicyorpositionoftheFAA.
CloudTopHeightdatawereobtainedfromtheNASALangleyCloudandRadiationResearchGroup,http://www-angler.larc.nasa.gov.GPMdatawereprovidedbytheNASAGoddardSpaceFlightCenter'sGPMscienceteamandPPS,whichdevelopandcomputetheGPMIMERGasacontributiontoGPM.DataarearchivedattheNASAGESDISC.
NOAARESEARCH•EARTHSYSTEMRESEARCHLABORATORY•GLOBALSYSTEMSDIVISION
No Icing
FillingDataGaps
GlobalTurbulenceObservationCoverage
IcingSeveritytoSoundings
§ PIREP,AIREP(pilotreports)§ EDR,TAMDAR (automaticaircraftsensor-derived)§ WMORegions(rectangles)
GPMandSurfaceRadar
Icingpotential–“InsideClass1”:§ RH>67%,§ -15°C<T<-2°C
NoIcingpotential–“OutsideClass1”:§ RH<50%,§ -25°C<T<0°C
ClassesdefinedbySchultzandPolitovich(1992)
Globallightning,GPMglobalprecipitationandradarechotops,geostationarycloudtopheights,andCloudSatreflectivitywereinvestigatedtoverifyEPOCH,whichgivesprobabilitiesofthunderstormsandconvectiveclouds>10,000ft.(9144m).
Greatestobservationalneeds§ Observationsoficingandturbulencethatareunbiased(i.e.,unbiased
bypilotchoices,etc.)§ Observationsfromaircraftsensorsthatreportwhenthesensorisiced,
ratherthancurrentpracticeofreportingonlyatregularintervals,whichmaymisssomeicingevents.
§ Spaced-basedmeasureoflowaltitudecloudbases.
R²=0.35794
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AMDA
R98%RHHe
ight(m)
METARCeilingHeight(m)
METARCeilings andAMDARRH>98%
ExampleofAMDARreportmatchingwellwithMETARceiling(redline)
CompareAMDARtoMETARAMDARobservationsofrelativehumidity,temperature,anddewpointwerecomparedwithMETARceilingheights.AMDARwerematchedtoMETARsforthefirst3,000feetduringtake-offandwithin±5minutes.§ METARceilingheightandfirstoccurrenceofanAMDAR
relativehumidity>98%wereweaklycorrelated(figureabove).
§ Largedisagreementsoccurredwithtwoscenarios:§ AMDAR RHthresholdheight>METARceilingwhenceilingis
“broken”;aircraftfliesthroughagapintheclouds.§ AMDARRHthresholdmayoccuratlowerheightthantheMETAR
ceilingwhen“few”or“scattered”cloudsoccurbelowtheceiling.
AdditionalworkisneededtoinvestigatewhytheAMDARrelativehumiditymeasurementsdonotreliablymatchtheMETARceilingheights.
GPMMicrowaveImager
andRadar
CloudTopHeight
Lightning
IMERGPrecipitation(>4mmper6hour)
2016-12-012300UTC
2016-12-011800-2300UTC
(km)
(Image from The COMET Program)
METARvsRadarsOPCproductwasevaluatingagainstsurfacereportsbyestablishingthedistributionofground-basedandsatelliteradarsignatureswitheachMETAR-basedpresentweathercategory.
VerticallyIntegratedLiquid(VIL,kg/m2)
GlobalPrecipitationMission(GPM)
SurfaceReports(METARs)
GroundRadarExtent
Six months of coverage
