(1)CentreforPolarObserva3onandModelling,UniversityofLeeds,Leeds,UnitedKingdom(m.mcmillan@leeds.ac.uk),(2)isardSATLtd,Guildford,UnitedKingdom,(3)CLS,RamonvilleSaint-Agne,France,(4)LEGOS,Toulouse,France,(5)ESAESRIN,Frasca3,Italy.

SPICEwilldevelopandtestSARprocessingalgorithms,aimingul3matelytoimproveSen3nel-3performanceovericesheets.

InPhase1,SPICEwillgeneratebaselinesolu3ons,usingcurrentlyimplementedprocessingapproaches.

InPhase2,SPICEwillinves3gatenovelalgorithmdevelopmentsaimedatimprovingSARretrievalsoficesheeteleva3on.

•  Delay-DopplerProcessing(DDP).SPICEprocessordevelopmentswillinclude:

1.  Accoun3ngfortheantennapaUernatthestacklevel,soastoconsidertheangleofeachDopplerbeam.

2.  EnablingDopplerbeamfocussingonpar3culartargetsofinterest.

3.  CleaningthestackssothattherangebinsofDopplerbeamswithnousefulinforma3onareremoved.

•  SAR retracking. In Phase 1, SPICE will inves3gate the performance of exis3ng retrackers. In Phase 2, SPICE willdeveloptwonewSARretrackers,basedonbothanewphysicalandanewempiricalmodel.

•  Pseudo-LRM(pLRM)processing.SPICEwilldevelopapLRMprocessingchain,toassessthefeasibilityofgenera3ngalowresolu3onproductfromaclosedburstSARsystem.Ifsuccessful,pLRMcanfacilitatethecrosscomparisonofpulselimitedandSARal3metry,asbothhigherlevelproductscanbegeneratedfromthesameFBRdata.

•  AspartoftheSPICEstudy,weareconduc3ngahighlevelevalua3onofalldataproducts,to assess the ability of SAR and pulse limited al3metry to determine reliablemeasurementsofsurfaceeleva3on.

•  At each study site, reference datasets comprised of airborne (IceBridge) and satellite(ICESat)measurementswillbeusedtoassesstheSPICEeleva3onproducts.

•  Intersec3ons between ground tracks are iden3fied (figure right) and eleva3ondifferencesrela3vetoeachreferencedatasetarecomputed.

•  To date, SPICE baseline datasets at Dome C and Vostok have been analysed. Results(figurebelow) indicate comparable levelsofperformancebetweendifferentopera3ngandprocessingmodes.Inpar3cular,theSPICEpLRMsolu3onshowspromisingresultsattheselowreliefstudysites.

•  Interferometric and SAR al3metry processing techniques were firstimplemented on an Earth Observing satellite in 2010, when CryoSat-2waslaunched.CryoSat-2SARacquisi3onswere,however,primarilylimitedtoseaiceandwatersurfaces.

•  Sen3nel-3, which launched early in 2016, now provides opera3onal SARal3metryoverbothicesheets.TheSPICEstudyaimstoaddresstheneedtoevaluateandop3miseSARprocessingtechniquesfortheseenvironments.

•  SPICEwillfocusonfourstudysites:

•  TheLakeVostok,DomeCandSpiritsitesinAntarc3ca,wherededicatedSARacquisi3onshavebeenmadebyCryoSat-2.

•  TheRussellGlacier inGreenland,whereSAR interferometric (SARIn)FullBitRate(FBR)datawillbeusedtogeneratepseudo-SARmeasurements.

CONTEXT&STUDYSITESSARPROCESSINGIMPROVEMENTOVERICESHEETS

FUTUREWORK

Independentevalua3onofal3metereleva3onsattheDomeCandVostoksites,usingairborne(IceBridge)andsatellite(ICESat2009campaigns)datasets.Ateachsite,SAR,LRMandpLRMeleva3onmeasurementshavebeencomparedto

eachofthereferencedatasets,andthedistribu3onofeleva3ondifferenceshasbeencalculated.

MalcolmMcMillan1*,RogerEscolà2,MònicaRoca2,MariaJoséEscorihuela2,PierreThibaut3,AndrewShepherd1,FrédériqueRemy4,JérômeBenveniste5,AméricoAmbrózio5andMarcoRestano5.

www.seom-spice.org|m.mcmillan@leeds.ac.uk|*CentreforPolarObserva3on&Modelling,UniversityofLeeds,UK

Theloca3onofSPICEstudysitesinAntarc3ca(mainpanel)andGreenland(inset).

•  SPICE (Sen3nel-3 Performance improvement for Ice sheets) is a 2 yearstudy funded by ESA’s SEOM (Scien3fic Exploita3on of Opera3onalMissions)program.

•  In prepara3on for Sen3nel-3, the project aims to contribute to thedevelopment and evalua3on of novel SyntheSc Aperture Radar (SAR)alSmetryprocessingmethodsovericesheets.

•  SPICE will process full bit rate (FBR) CryoSat-2 SAR acquisi3ons usingexis3ngbaselines,generatenovelSARandpseudo-LRM(pLRM)products,and inves3gate the expected performance of Sen3nel-3 prior toopera3onaldataavailability.

SUMMARY

AssessandimproveDelay-Doppleral3meterprocessingforicesheets

EvaluatetheperformanceofSARal3metryrela3vetoconven3onal

pulselimitedal3metry.

AssessanddevelopSARwaveformretrackersforicesheets.

AssesstheimpactonSARal3metermeasurementsofradarwaveinterac3on

withthesnowpack.OBJECTIVES

eleva3

on(m

)

CryoSat-2 LRM CryoSat-2 SAR

SPICE baseline SAR

SPICE pLRM

3000

3100

3200

3250

3150

3050

•  SPICEPhase2.

DuringPhase2,wewilldevelopandassesnewalgorithms,aimedat improvingtheDelay-Dopplerandretrackingprocessingchains.SPICE aims to draw on experiences from othermissions (for example Sen3nel-6 development) and related fields of research (forexampleSAMOSAoceanretracking)tocontributetotheimprovementofSARal3metryovericesheets.

•  RadarwaveinteracSonwiththesnowpack.

SPICEwillalsoinves3gatetheimpactonSARal3metryofradarwaveinterac3onwiththesnowpack.Firstly,theeffectofbackscaUeringanisotropywillbeassessedbycomparingmeasurementsacquiredfromdifferentviewingdirec3ons.Secondly,acomparisonbetweenCryoSat-2Ku-bandandSARALKa-bandmeasurementswillbeusedtoinves3gateradarwavepenetra3onintothesnowpack.

SPICEPERFORMANCEEVALUATION

Surfaceeleva3on(m)

IceBridgetracks

SPICEtrackscrossingpointsSPICEpLRM

SPICEbaselineSAR

recordnum

ber

recordnum

ber

increasingeleva3on

increasingeleva3on

Topandmiddlepanels.SPICEpLRMandSARwaveformsgeneratedfromthesameSARFBRdata,foratrackcrossingDomeC.BoWompanel.SPICEbaselineSARandpLRMeleva3onsforatrackcrossingDomeC(loca3onshownininsetfigure),comparedtotherangeofCryoSat-2BaselineCLRM

solu3ons.SARandpLRMprofilesarefromdedicatedSARacquisi3onsin2014.TheLRMdataarefromanearcoincidenttrackfromthefollowingorbitcycle.Allsolu3onsresolveabroadlyconsistenttopography,withoffsetsoftheorderof1meterduetothedifferentretrackersused.

Intersec3onsbetweenSPICEandIceBridgereferencedatasetsatDomeC.

C11A-0747.SenSnel-3PerformanceimprovementforIcesheets

CryoSat-2LRM

CryoSat-2SA

R

SPICEbaselineSA

R

SPICEpLRM

CryoSat-2LRM

CryoSat-2SA

R

SPICEbaselineSA

R

SPICEpLRM

CryoSat-2LRM

CryoSat-2SA

R

SPICEbaselineSA

R

SPICEpLRM

CryoSat-2LRM

CryoSat-2SA

R

SPICEbaselineSA

R

SPICEpLRM

22measurements 470measurements80measurements25measurements