C11A-0747. Sennel-3 Performance improvement for Ice sheets · 2017. 3. 6. · Guildford, United...
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(1) Centre for Polar Observa3on and Modelling, University of Leeds, Leeds, United Kingdom ([email protected]), (2) isardSAT Ltd, Guildford, United Kingdom, (3) CLS, Ramonville Saint-Agne, France, (4) LEGOS, Toulouse, France, (5) ESA ESRIN, Frasca3, Italy. SPICE will develop and test SAR processing algorithms, aiming ul3mately to improve Sen3nel-3 performance over ice sheets. In Phase 1, SPICE will generate baseline solu3ons, using currently implemented processing approaches. In Phase 2, SPICE will inves3gate novel algorithm developments aimed at improving SAR retrievals of ice sheet eleva3on. • Delay-Doppler Processing (DDP) . SPICE processor developments will include: 1. Accoun3ng for the antenna paUern at the stack level, so as to consider the angle of each Doppler beam. 2. Enabling Doppler beam focussing on par3cular targets of interest. 3. Cleaning the stacks so that the range bins of Doppler beams with no useful informa3on are removed. • SAR retracking . In Phase 1, SPICE will inves3gate the performance of exis3ng retrackers. In Phase 2, SPICE will develop two new SAR retrackers, based on both a new physical and a new empirical model. • Pseudo-LRM ( pLRM ) processing. SPICE will develop a pLRM processing chain, to assess the feasibility of genera3ng a low resolu3on product from a closed burst SAR system. If successful, pLRM can facilitate the cross comparison of pulse limited and SAR al3metry, as both higher level products can be generated from the same FBR data. • As part of the SPICE study, we are conduc3ng a high level evalua3on of all data products, to assess the ability of SAR and pulse limited al3metry to determine reliable measurements of surface eleva3on. • At each study site, reference datasets comprised of airborne (IceBridge) and satellite (ICESat) measurements will be used to assess the SPICE eleva3on products. • Intersec3ons between ground tracks are iden3fied (figure right) and eleva3on differences rela3ve to each reference dataset are computed. • To date, SPICE baseline datasets at Dome C and Vostok have been analysed. Results (figure below) indicate comparable levels of performance between different opera3ng and processing modes. In par3cular, the SPICE pLRM solu3on shows promising results at these low relief study sites. • Interferometric and SAR al3metry processing techniques were first implemented on an Earth Observing satellite in 2010, when CryoSat-2 was launched. CryoSat-2 SAR acquisi3ons were, however, primarily limited to sea ice and water surfaces. • Sen3nel-3, which launched early in 2016, now provides opera3onal SAR al3metry over both ice sheets. The SPICE study aims to address the need to evaluate and op3mise SAR processing techniques for these environments. • SPICE will focus on four study sites: • The Lake Vostok, Dome C and Spirit sites in Antarc3ca, where dedicated SAR acquisi3ons have been made by CryoSat-2. • The Russell Glacier in Greenland, where SAR interferometric (SARIn) Full Bit Rate (FBR) data will be used to generate pseudo-SAR measurements. CONTEXT & STUDY SITES SAR PROCESSING IMPROVEMENT OVER ICE SHEETS FUTURE WORK Independent evalua3on of al3meter eleva3ons at the Dome C and Vostok sites, using airborne (IceBridge) and satellite (ICESat 2009 campaigns) datasets. At each site, SAR, LRM and pLRM eleva3on measurements have been compared to each of the reference datasets, and the distribu3on of eleva3on differences has been calculated. Malcolm McMillan 1* , Roger Escolà 2 , Mònica Roca 2 , Maria José Escorihuela 2 , Pierre Thibaut 3 , Andrew Shepherd 1 , Frédérique Remy 4 , Jérôme Benveniste 5 , Américo Ambrózio 5 and Marco Restano 5 . www.seom-spice.org | [email protected] | *Centre for Polar Observa3on & Modelling, University of Leeds, UK The loca3on of SPICE study sites in Antarc3ca (main panel) and Greenland (inset). • SPICE (Sen3nel-3 Performance improvement for Ice sheets) is a 2 year study funded by ESA’s SEOM (Scien3fic Exploita3on of Opera3onal Missions) program. • In prepara3on for Sen3nel-3, the project aims to contribute to the development and evalua3on of novel SyntheSc Aperture Radar (SAR) alSmetry processing methods over ice sheets. • SPICE will process full bit rate (FBR) CryoSat-2 SAR acquisi3ons using exis3ng baselines, generate novel SAR and pseudo-LRM (pLRM) products, and inves3gate the expected performance of Sen3nel-3 prior to opera3onal data availability. SUMMARY Assess and improve Delay-Doppler al3meter processing for ice sheets Evaluate the performance of SAR al3metry rela3ve to conven3onal pulse limited al3metry. Assess and develop SAR waveform retrackers for ice sheets. Assess the impact on SAR al3meter measurements of radar wave interac3on with the snowpack. OBJECTIVES eleva3on (m) CryoSat-2 LRM CryoSat-2 SAR SPICE baseline SAR SPICE pLRM 3000 3100 3200 3250 3150 3050 • SPICE Phase 2. During Phase 2, we will develop and asses new algorithms, aimed at improving the Delay-Doppler and retracking processing chains. SPICE aims to draw on experiences from other missions (for example Sen3nel-6 development) and related fields of research (for example SAMOSA ocean retracking) to contribute to the improvement of SAR al3metry over ice sheets. • Radar wave interacSon with the snowpack. SPICE will also inves3gate the impact on SAR al3metry of radar wave interac3on with the snowpack. Firstly, the effect of backscaUering anisotropy will be assessed by comparing measurements acquired from different viewing direc3ons. Secondly, a comparison between CryoSat-2 Ku-band and SARAL Ka-band measurements will be used to inves3gate radar wave penetra3on into the snowpack. SPICE PERFORMANCE EVALUATION Surface eleva3on (m) IceBridge tracks SPICE tracks crossing points SPICE pLRM SPICE baseline SAR record number record number increasing eleva3on increasing eleva3on Top and middle panels. SPICE pLRM and SAR waveforms generated from the same SAR FBR data, for a track crossing Dome C . BoWom panel. SPICE baseline SAR and pLRM eleva3ons for a track crossing Dome C (loca3on shown in inset figure), compared to the range of CryoSat-2 Baseline C LRM solu3ons. SAR and pLRM profiles are from dedicated SAR acquisi3ons in 2014. The LRM data are from a near coincident track from the following orbit cycle. All solu3ons resolve a broadly consistent topography, with offsets of the order of 1 meter due to the different retrackers used. Intersec3ons between SPICE and IceBridge reference datasets at Dome C. C11A-0747. SenSnel-3 Performance improvement for Ice sheets CryoSat-2 LRM CryoSat-2 SAR SPICE baseline SAR SPICE pLRM CryoSat-2 LRM CryoSat-2 SAR SPICE baseline SAR SPICE pLRM CryoSat-2 LRM CryoSat-2 SAR SPICE baseline SAR SPICE pLRM CryoSat-2 LRM CryoSat-2 SAR SPICE baseline SAR SPICE pLRM 22 measurements 470 measurements 80 measurements 25 measurements
Transcript of C11A-0747. Sennel-3 Performance improvement for Ice sheets · 2017. 3. 6. · Guildford, United...
(1)CentreforPolarObserva3onandModelling,UniversityofLeeds,Leeds,UnitedKingdom([email protected]),(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|[email protected]|*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
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SPICEpLRM
CryoSat-2LRM
CryoSat-2SA
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SPICEbaselineSA
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SPICEpLRM
CryoSat-2LRM
CryoSat-2SA
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SPICEbaselineSA
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SPICEpLRM
CryoSat-2LRM
CryoSat-2SA
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SPICEbaselineSA
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22measurements 470measurements80measurements25measurements
