Fidelity(and(Uncertainty(in(Climate(Data(Records(from(Earth(Observa:on( (FIDUCEO)( Christopher(J.(Merchant(University*of*Reading,*UK*! Jonathan(MiBaz(University*of*Reading*and*Na4onal*Physical*Laboratory,*UK**! Emma(Woolliams(Na4onal*Physical*Laboratory,*UK! Overview( ( Well%characterised!uncertain0es!are!crucial!if!Climate!Data!Records!(CDRs)!are!to!be!properly!exploited.!!! Our!understanding!of!CDR!uncertain0es!is,!however,!currently!limited.!!For!example,!how!trustworthy!is!the! uncertainty!on!a!given!measurement!of!a!climate!variable?!If!we!compare!a!measurement!now!with!one! obtained!a!few!decades!earlier,!how!uncertain!is!the!apparent!change?!To!what!extent!do!instrumental!and! mul0%mission!(in)stability!limit!the!conclusions!that!can!be!drawn!about!clima0c!trends?!!! ! The!objec0ve!of!the!FIDUCEO!project!is!to!develop!new!methods!to!such!these!ques0ons!for!CDRs!derived! from!satellite!observa0ons.!The!methods!will!be!developed!by!adap0ng!insights!and!techniques!from!the! discipline!of!metrology,!the!“science!of!measurement!uncertainty”!and!of!uncertainty!traceability.!They!will! be!demonstrated!!across!microwave,!infra%red!and!visible!domains.!! Example(metrologyHbased(analysis:(( Tracing(cumula:ng(uncertain:es(in( AVHRR(thermal(radiance(data( ! An!“instrument!model”,!such!as!that!below,!captures!the! physical!eﬀects!and!data!transforma0ons!that!determine!the! calibrated!radiance!that!is!the!“level!1”!product!from!a!sensor! such!as!the!Advanced!Very!High!Resolu0on!Radiometer.! ! In!this!example!below,!reference!measurements!from!other! sensors!are!used!for!cross%calibra0on,!to!improve!on!the! nominal!pre%launch!characterisa0on!using!data!in!ﬂight.! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! The!magnitudes!and!correla0on!proper0es!of!error! distribu0ons!for!radiance!data!given!the!new!calibra0on!and! instrument!behaviour!can!be!characterised!by!error!modelling! and!propaga0on!through!all!elements!of!the!corresponding! “uncertainty!chain”.! ! In!FIDUCEO,!new!harmonised!level!1!datasets!in!an!easy%to%use! FCDR!format!will!be!created.!This!will!apply!state%of%the%art! calibra0on,!and!include!rigorous!uncertainty!informa0on,!using! uncertainty!chains!as!discussed!above.! ! Easy%FCDR!datasets!will!make!it!much!easier!for!uncertainty% characterised,!harmonised!geophysical!datasets!to!be!derived! from!several!important!series!of!instruments!(AVHRR,!HIRS,! AMSU,!Meteosat).!In!this!way,!FIDUCEO!is!intended!to!enable! widespread!rigorous!exploita0on!of!long%term!satellite!data!for! new!climate!variables.! Earth& Space& (electronic&clamp)& Detector& (δC)& Internal&Calibra7on&Target& Thermal& Gradients& PRT&Biases/& uncertain7es& Digi7za7on& Interpola7on/& Smoothing& SRF& (δSRF)&& Emissivity&& (nonFblackness)& ε& Solar& scaIering& Earthshine& Colloca7on&to&Reference& Geoloca7on& uncertain7es& SRF&conversion& uncertain7es& Time&diﬀerences& ΔR& (δΔR)& NonFlinear&ﬁt& Instrument& model&error& Calibra7on& Equa7on& Top&of& Atmosphere& Reference& (A)ATSR/IASI& etc& REarth(+RInstr(E)) RInstr(sp) RICT + RRel CEarth(δC),CICT,CSpace( δC 10 ) RICT (+RInstr(ICT)) (δRICT ) TICT (δTICT ) REarth(calibrated)+δR a0,Δε,a1,a2 (δa0,δΔε,δa1,δa2) Concept(of(FIDUCEO(project( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( FIDUCEO!will!create!new!methods,!tools,!training!and!datasets.! ! The!new!methods!will!address!new!physics%based!harmonisa0on!techniques!for!series! of!key!sensors,!and!corresponding!es0ma0on!of!all!signiﬁcant!components!of! uncertainty!(including!pixel!level!and!long!term!stability)!in!a!metrologically!robust! manner.! ! The!applica0on!of!these!methods!within!the!project!will!lead!to!four!new!Fundamental! Climate!Data!Records!(FCDRs)!–!Meteosat!(VIS),!AVHRR!&!HIRS!(IR)!and!microwave! humidity!sounders!(MW).! ! Based!on!these!FCDRs,!within!FIDUCEO!we!will!demonstrate!extension!of!the! metrological!approach!to!geophysical!datasets!(CDRs).!The!CDRs!will!address!upper% tropospheric!humidity,!surface!temperature!and!albedo,!and!aerosol!op0cal!depth.!! ! ! ! ! ! ! ! ! !