International GNSS Service (IGS)maintain and develop the IGS organization and improve its...
Transcript of International GNSS Service (IGS)maintain and develop the IGS organization and improve its...
InternationalGNSSService(IGS)
http://www.igs.org
ChairoftheGoverningBoard:GaryJohnston
(Australia)
DirectoroftheCentralBureau:RuthNeilan(USA)
ApplicationsoftheGlobalNavigationSatelliteSystems(GNSS)toEarthSciencesandtechnologyarenumerousandgrowing.TheInternationalGNSSService(IGS),avoluntaryfederationofgovernmentagencies,universitiesandresearchinstitutions,combinesGNSSresourcesandexpertisetoprovidethehighest–qualityGNSSdata,products,andservicesinordertosupporthigh–precisionapplicationsforGNSS–relatedresearchandengineeringactivities.TheIGShasbeenaserviceoftheIAGsince1994.
OverviewTheIGShascontinuedtosupportscientificandotherGNSSusersthroughthe2015-2017reporting
period.TheIGSprovidesessentialproductsthatcontributetotherealizationofITRFandenablevery
highaccuracypositioningusingGNSStechnologiesforscientific,andawidevarietyofotheruses.The
Servicealsoprovidesanumberofexperimentalproducts,inacontinuousefforttoencourage
technologicalandanalyticalimprovement.IGScontinuestorefinetheaccuracyandconsistencyofits
productsbyanongoingprocessofbothtechniqueimprovementandreprocessingofpastdatasetsin
ordertoachievethehighestqualityresults.
TheIGScontinuestoadaptandcontributetoadvancesintechnology,includingongoingandincreased
effortsfortransitioningtoamulti-GNSSservice,aswellasadvancingreal-timeapplications.Re-tooling
andmodernizationofcapabilities,aswellasdevelopingandextendingrelevantstandards,havealso
beensignificanteffortswithintheIGS.
Inadditiontomanytechnicalachievements,theIGScontinueswithproactiveeffortstosustainablymaintainanddeveloptheIGSorganizationandimproveitsmanagement.Startingwherethe2013-2016StrategicPlanended,acomprehensiveusersurveyandstrategicplanningprocesstookplaceinlate2016andearly2017.Theresulting2017StrategicPlanhasbeendevelopedinresponsetoboththeuser
andcommunitysurveyresponsesaswellascontinuingkeyelementsofthepreviousstrategicplan’sgoalsandobjectives.ItalsoaimstorecognizetheextensivecontributionoftheIGSparticipants,andtoencouragestrongengagementwithabroaderstakeholdersetthatnowrelyimplicitlyonIGSproductsandservices.
TheIGSTermsofReference,aswellastheassociatemembership,havebeenreviewedannuallybythe
GoverningBoardandrelevantcommitteessince2011,withupdatestobothinthelastyear.Allcurrent
IGSorganizationaldocumentsandcomponentmembershiprostersaremaintainedintheIGSKnowledge
Basewebsite:http://kb.igs.org/.
Byworkingwithinthesciencecommunitythrough(IAG/IUGG/ICSU)andtheinter-governmentalcommunitythroughICG/UNGGIM/USPNTABandothers,theIGSGBisensuringtheIGSretainsitsstronglevelofrelevanceandimpact,andthereforesustainability.
EventsandMilestonesMGEXExperimentTransitiontoServiceandPilotProjectThesuccessoftheMGEXexperimenthasdemonstratedtheinevitabilityofatransitionoftheIGStoafullmulti–GNSSService.Accordingly,theGoverningBoarddecidedtoacknowledgethisbyterminatingthe“experiment”statusandmoveMGEXtothestatusofaPilotProject.Continuedeffortsarerequiredtonegotiateaccesstosatellitespecificinformationfornewsatellitesfromsystemproviders,allowingformorerealisticmodelsofsatellitebehaviortobedevelopedandutilizedbytheIGSAC’s.WuhanDataCenterIn2015theGoverningBoardendorsedtheproposalbyWuhanUniversity,China,tobecomeanIGSGlobalDataCenter.TheWuhanDataCenteroffersaccesstothefullcollectionofIGSdataandproductstoanyuserglobally,especiallythosewithintheAsiaPacificRegion.ImportantlythedatacentergivesdirectaccesstotheIGSdataholdingstotheverylargeresearchsectorwithinChina.
NewAnalysisCenterCoordinatorIGShascontinuedwithaveryexcitingworkprogramandlistofachievementsfromtheIGSparticipantsandcontributingorganizations.TheroleofAnalysisCentreCoordinator(ACC)isnowdistributedacrosstwocenters,GeoscienceAustraliaandMIT,intwocontinents,hemispheresapart,usingcombinationsoftwareoperatingonCloudcomputingservices(AmazonWebServices).
IGS2016WorkshopinSydney,Australia
In2016,theIGShaditsfirstworkshoptobeheldoutsideofNorthAmericaorEurope,withtheSydneyWorkshopheldinFebruary2016attheUniversityofNewSouthWales.Thisworkshop,thefirstinSouthEastAsia,andthefirstinthesouthernhemisphere,signaledthestrongerinvolvementofBeiDouandQZSSintotheIGS’sGNSSfuturesandfeaturedkeynotepresentationsfromToddHumphreys(UniversityofTexasatAustin),JanWeiss(UCAR),andJohnChurch(CSIRO),aswellasover50plenarypresentationsand57posters.Keynotes,presentations,andpostersmaybeviewedontheIGSwebsite:http://www.igs.org/presents/workshop2016.
IGS-UNICGCollaborationonGNSSMonitoringandAssessmentIGSplayedakeyroleinformingtheUnitedNationsInternationalCommitteeonGNSS(ICG)InternationalGNSSMonitoringandAssessment(IGMA)TaskForce,andInternationalGNSSService(IGS)JointGNSSMonitoringWorkingGroupmetconcurrenttotheSydneyworkshop.TheCallforProposalsforparticipationintheIGS/ICGjointMonitoringandAssessmentprojectisapragmaticexampleoftheIGSbeingflexibleenoughtorespondtostakeholderrequirements.ThatprojectaimstoutilizeexistingskillswithintheIGScommunitytoserviceanewusercommunityasanextensiontoourcurrentroleofprovidingworldclassGNSSexpertise.TheCallforParticipationhadastrongresponseincludingaproposalfromESAtoundertaketheMonitoringandAssessmentACCfunction.ImportantlythisnewjointprojectensurestheIGScontinuestohavestronginfluencewithGNSSsystemproviders.ThisstrongrelationshiphasbeendevelopedovermanyyearsbyIGSparticipationintheICG.
Publications,Presentations,OutreachComprehensivelistsofIGSpublicationssince2015,aswellaspublicationsreferencingIGSinthat
timeframe,maybefound,organizedaccordingtoIGScomponent,inthe2015TechnicalReportaswell
asthe2016TechnicalReport.
Figure1:TheIGSAt-a-Glance
IGSStructureTheIGSisaself-governedfederationof388contributingorganizationsfrom118countriesaroundthe
worldthatcollectivelyoperateaglobalinfrastructureoftrackingstations,datacentersandanalysis
centerstoprovidehighqualityGNSSdataproducts.TheIGSproductsareprovidedopenlyforthe
benefitofallscientific,educational,andcommercialusers.TheIGSisgovernedbyaninternational
GoverningBoard(Table1)thatiselectedbydesignatedAssociateMemberswhorepresenttheprincipal
IGSparticipants.ExecutivemanagementoftheIGSiscarriedoutbytheCentralBureau,asis
coordinationoftheIGSTrackingNetworkandmanagementoftheIGSwebportalthatprovides
centralizedaccesstoIGSproductsandinformation.IGSproductsaregeneratedbycombiningresults
fromdifferentAnalysisCentersunderthedirectionoftheAnalysisCoordinatorandspecificProduct
Coordinators.IntroductionofnewproductsandspecifictechnicalissuesareaddressedthroughPilot
ProjectsandWorkingGroupsoftechnicalexperts(Table2).TheIGSorganizationisdepictedinFigure2.
Table1:IGSGoverningBoardMembers,asofMay2017
Status First Last Affiliation Country Role ServiceYears
EC-V Gary Johnston GeoscienceAustralia Australia BoardChair 2010-2018
Michael Moore GeoscienceAustralia Australia AnalysisCenterCo-Coordinators
2016-2019
EC-V Chris Rizos UniversityofNewSouthWales Australia IAGappointed 2004-2019
V Carine Bruyninx RoyalObservatoryofBelgiumObservatoireRoyaldeBelgique(ORB)
Belgium IGSNetworkRepresentative
2011-2017
Ken MacLeod NaturalResourcesCanada/RessourcesnaturellesCanada
Canada RINEX-RTCMWorkingGroupChair
2012-2019
V Felicitas Arias BureauInternationaldesPoidsetMesures
France BIPM/CCTFRepresentative
2005-Present
V Zuheir Altamimi InstitutNationaldel'InformationGéographiqueetForestière
France IAGRepresentative 2011-2019
V Paul Rebischung InstitutNationaldel'InformationGéographiqueetForestière
France IGSReferenceFrameCoordinator
2017-2020
V Laura Sanchez DeutschesGeodätischesForschungsinstitut
Germany NetworkRepresentative
2014-2017
V Mathias Fritsche DeutschesGeoForschungsZentrum(GFZ)
Germany AnalysisCenterRepresentative
2015-2019
Oliver Montenbruck DeutschesZentrumfürLuft-undRaumfahrte.V.
Germany Multi-GNSSWorkingGroupChair
2012-2020
Tilo Schöne DeutschesGeoForschungsZentrumPotsdam
Germany TIGAWorkingGroupChair
2001-2020
V Loukis Agrotis ESA/EuropeanSpaceOperationsCentre
Germany Real-timeAnalysisCoordinator
2014-2017
V Werner Enderle ESA/EuropeanSpaceOperationsCentre
Germany Appointed(IGS) 2016-2017
Ignacio Romero ESA/EuropeanSpaceOperationsCentre
Germany InfrastructureCommitteeChair
2010-2017
Axel Ruelke FederalAgencyforCartographyandGeodesy(BKG)
Germany Real-timeWorkingGroup,Chair
2016-2019
V Satoshi Kogure JapanAerospaceExplorationAgency(JAXA)
Japan Appointed(IGS) 2014-2017
Andrzej Krankowski UniversityofWarmiaandMazuryinOlsztyn
Poland IonosphereWorkingGroupChair
2007-2020
EC-V,IR
Rolf Dach AstronomicalInstitute,UniversityofBern
Switzerland AnalysisCenterRepresentative
2015-2018
Arturo Villiger AstronomicalInstitute,UniversityofBern
Switzerland AntennaWorkingGroupChair
2017-2020
Stefan Schaer FederalOfficeofTopography-swisstopo
Switzerland Calibration&BiasWorkingGroupChair
2007-2020
Marek Ziebart UniversityCollegeLondon UK AnalysisCenterCoordinator
2011-2020
EC-V Ruth Neilan IGSCentralBureau,JetPropulsionLaboratory
USA DirectorofIGSCentralBureau
1994-Present
Table2:IGSWorkingGroupsandProjects
Antenna
CoordinatesresearchinthefieldofGNSSreceiverandsatelliteantennaphasecenterdetermination
ArturoVilliger,Chair
BiasandCalibration
UpdatesvariousbiasvaluesandrelatedauxiliaryinformationforconsistentGNSSanalysis(productgeneration),e.g.,differentialcodebiases;definesstandardsanddataexchangeformatsinthefieldofGNSSbiases
StefanSchaer,Chair
ClockProducts
Globalsub-nanosecondtimetransfer,andIGStime-scale,jointlywiththeBureauInternationaldesPoidsetMesures(BIPM)
MichaelColeman,Chair
DataCenter
CoordinationamongIGSdatacentersandsupportforincreasingnumberofproductsandreal-time
CareyNoll,Chair
IGMAMonitoring
UnitedNationsInternationalCommitteeonGNSS(ICG)InternationalGNSSMonitoringandAssessment(IGMA)TaskForceandInternationalGNSSService(IGS)JointGNSSMonitoringWorkingGroup
UrsHugentobler,Chair
Ionosphere
Ionosphericscienceresearch,globalionosphericmapsAndrzejKrankowski,Chair
V Shailen Desai JetPropulsionLaboratory USA AnalysisCenterRepresentative
2012-2019
V Richard Gross JetPropulsionLaboratory USA IERSRepresentative 2015-2019
V Thomas Herring MassachusettsInstituteofTechnology(MIT)
USA AnalysisCenterCoordinator
2016-2019
Carey Noll NASAGoddardSpaceFlightCenter USA DataCenterWorkingGroupChair
2006-2019
V Michael Coleman NavalResearchLaboratory USA IGSClockProductsCoordinator
2014-2017
V Fran Boler UNAVCO USA DataCenterRepresentative
2014-2017
David Maggert UNAVCO USA NetworkCoordinator 2015-2019
EC-V,IR
Charles Meertens UNAVCO USA Appointed(IGS) 2011-2018
Sharyl Byram UnitedStatesNavalObservatory USA TroposphereWorkingGroup,Chair
2016-2019
Multi-GNSSWGandMulti-GNSSExtension(MGEX)Project
DetermineactionsnecessaryforIGStoco-optnewGNSSsystems,EuropeanUnion'sGalileosystem,China’sBeiDou,andGPSmodernization
OliverMontenbruck,Chair
Real-timeWGandReal-TimeService DemonstrateforIGSreal-timenetworkandapplicationsAxelRülke,Chair
ReferenceFrame
Globalreferenceframe,Earthorientation,stationpositionsandvelocitiesdeterminedbyGNSS
PaulRebischung,Chair
RINEX
CoordinatesthedevelopmentofGNSSobservation,navigationandmetadataformats
KenMacLeod,Chair
SpaceVehicleOrbitDynamics
Improvedunderstandingandmodelingofsatellitedynamicstowardsfurtherimprovementofpreciseorbitdetermination
MarekZiebart,Chair
TideGauge(TIGA)
Monitorlong-termsea-levelchange,attempttode-couplecrustalmotion/subsidenceatcoastalsitesfromtheirtidegaugerecords
TiloSchöne,Chair
Troposphere
EstimatewatervaporinatmospherefromtheGPSsignaldelaySharylByram,Chair
IGMAJointPerformanceMonitoring
AimedatcreatinganauthoritativeinternationalGNSSmonitoringandassessmentsystemtobenchmarktheperformanceofavailableGNSSs
TimSpringer,Chair
Figure2:IGSOrganization
OperationalActivitiesDeliveryofcorereferenceframe,orbit,clockandatmosphericproductscontinuedstrongly,withfurtherrefinementoftheReal-TimeServiceandconsiderableeffortsbeingtargetedtowardsdevelopmentofstandards.Thetransitiontomulti-GNSSalsocontinued,withadditionalGalileoandBeiDousatellitelaunchesbringingthoseconstellationsclosertooperationalstatus.
Over500IGSNetworkstationsaremaintainedandoperatedgloballybymanyinstitutionsandstationoperators,makingtrackingdataavailableatlatenciesrangingfromdailyRINEXfilestoreal-timestreamsavailableforfreepublicuse(Figure2).Thedevelopmentofamulti-GNSSsub-networkwiththegreaterIGSnetworkisledbytheMGEXproject,whichdevelopstheIGS’scapabilitytooperatewithmultipleGNSSconstellations,andhas177multi-GNSScapable(GPS+GLONASS+oneother)stations.Withinthenetwork,189IGSstationsarenowcapableofreal-timedatastreaminginsupportoftheIGSReal-TimeService.
TheCentralBureauassumesresponsibilityforday-to-daymanagement,interactionwithstation
operators,andansweringuserquestionsandrequests.ThequantityofIGStrackingdataheldon
permanentlyaccessibleserversateachofthefourglobaldatacentersincreasedatalmost2Terabytes
peryeartowhatisnowapproximately10Terabyte(over100millionfiles).Significantadditionalstorage
capabilitiesareprovidedbyregionaldatacenters.Itisestimatedthatapproximately20,000usersvisit
theIGSwebsiteandrelatedresourceseachmonth.
Figure3:IGSTrackingNetwork
Thirteenanalysiscentersand21associateanalysiscentersutilizetrackingdatafrombetween70and
350stations,fourtimesperday,togenerateandverifythequalityofhighestprecisionproducts.
Productcoordinatorscombinetheseproductsonanoperationalbasisandassurethequalityofthe
productsmadeavailabletotheusers.IGSproductuseractivitydocumentation,courtesyofCDDIS,
revealsthatin2017(January-August),anaverage106MGNSSfiles/12TBweredownloadedpermonth;
thisincludesGNSSdataandproductfiles.FocusingonIGNSproductfilesonly,thenthosetotalsare26M
GNSSproductfiles/4.5TBonaveragepermonth.ForTroposphericdownloads,CDDISreportsover46M
filestotalingover125GBin2016from500Kuniquehostseachmonth.
Alltheseactivitiesareperformedonadailybasis,year-round,withhighredundancyandreliability
basedonthepooledresourcesofmorethan200institutionsworldwide.Onlythedailycontributionsof
alargenumberofengagedindividualsmakesthissignificantundertakingpossible.
ProductQualityTheIGSAnalysisCentershavecontinuedtoimproveproductprecision,consistencyandavailability.IGS
“final”orbitsnowagreeatalevelofapproximately2cm,andfinalsatelliteclocksolutionsagreeat
approximately75psRMSwith20psstandarddeviation.ThefinalX-andY-polesolutionsagreeat
approximately0.03mas,andthefinallengthofdaysolutionsagreeatapproximately0.01μs.Products
havecontinuedtobeavailabletousers,continuouslymeetingorexceedingthespecifiedavailability
thresholds(Table3).
Table3:IGSProductQualityandAvailability
GPS Satellite Ephemerides / Satellite and Station Clocks
Sample Interval
Accuracy Latency Continuity Availability
Broadcast (for comparison)
Orbits
Daily
~100 cm
real time Continuous 99.99% Sat. Clocks
~5 ns RMS; ~2.5 ns
Sdev
Ultra-Rapid (predicted half)
Orbits
15 min
~5 cm
predicted 4x daily, at
03, 09, 15, 21 UTC
99.70%Sat. Clocks
~3 ns RMS; ~1.5 Sdev
Ultra-Rapid (observed half)
Orbits
15 min
~3 cm
3-9 hours 4x daily, at
03, 09, 15, 21 UTC
99.40%Sat. Clocks
~150 ps RMS; ~50
ps Sdev
Rapid
Orbits 15 min ~2.5 cm
17-41 hours daily, at 17
UTC 99.70%
Sat. & Stn. Clocks 5 min ~75 ps
RMS; ~25 ps Sdev
Final
Orbits 15 min ~2 cm
12-18 days weekly, every
Thursday 100%
Sat. & Stn. Clocks Sat: 30 s;
Stn.: 5 min 75 ps RMS; 20 ps Sdev
Real-time
Orbits 5-60 s ~5 cm
25 seconds Continuous 100.00%Sat. Clocks 5 s
300 ps RMS;
120 ps Sdev
Note 1: Orbit accuracies are 1D mean RMS values over the three XYZ geocentric components. IGS accuracy limits, except for predicted orbits, are based on comparisons with independent laser ranging results and discontinuities between consecutive days. The precision is better.
Note 2: The accuracy (neglecting any contributions from internal instrumental delays, which must be calibrated separately) of all clocks is expressed relative to the IGS timescale, which is linearly aligned to GPS time in one-day segments. The standard deviation (SDev) values are computed by removing a separate bias for each satellite and station clock, whereas this is not done for the RMS values.
Note 3: Availability is the percentage of time that accuracy and continuity of service meet stated specification.
GLONASS Satellite Ephemerides Sample Interval
Accuracy Latency Continuity Availability
Final 15 min ~3 cm 12-18 days weekly, every
Thursday 100%
Geocentric Coordinates of IGS Tracking Stations (over 250 Sites)
Sample Interval
Accuracy Latency Continuity Availability
PositionsofReal-timeStations
Horizontal daily
3 mm 1-2 hours daily 100%
Vertical 6 mm
Final Positions Horizontal
weekly 3 mm
11-17 days weekly, every
Wednesday 100%
Vertical 6 mm
Final Velocities Horizontal
weekly 2 mm/yr
11-17 days weekly, every
Wednesday 100%
Vertical 3 mm/yr
Earth Rotation Parameters
Ultra-Rapid (predicted half)
Polar Motion daily
integrations at 00, 06
12, 18 UTC
~200 µas
real time 4x daily, at 03, 09, 15,
21 UTC 99.70%
Polar Motion Rate
~300 µas/day
Length-of-day ~50 µs
Ultra-Rapid (observed half)
Polar Motion daily
integrations at 00, 06,
12, 18 UTC
~50 µas
3-9 hours 4x daily, at 03, 09, 15,
21 UTC 99.70%
Polar Motion Rate
~250 µas/day
Length-of-day ~10 µs
Rapid
Polar Motion daily
integrations at 12 UTC
~40 µas
17-41 hours daily at 17
UTC 100%
Polar Motion Rate
~200 µas/day
Length-of-day ~10 µs
Final
Polar Motion
daily integrations at 12 UTC
0.03 mas
~11-17 days weekly, every
Wednesday 100%
Polar Motion Rate
~150 µas/day
Length-of-day 0.01 ms
Note 1: 100 µas = 3.1 mm of equatorial rotation; 10 µs = 4.6 mm of equatorial rotation. Note 2: The IGS uses VLBI results from IERS Bulletin A to partially calibrate for LOD biases over 21-day sliding window, but residual time-correlated LOD errors remain.
Atmospheric Parameters Sample Interval
Accuracy Latency Continuity Availability
IGS Final Tropospheric
Delay: zenith path delay (ZPD) plus
north, east gradients
5 min ~4 mm for
ZPD ~ 3 weeks daily 100%
Ionosphere TEC Grid
2 hours; 5 deg (Lon.)
x 2.5 deg (Lat.)
2-8 TECU ~11 days weekly 100%
Rapid ionosphere TEC Grid
2 hours; 5 deg (Lon.)
x 2.5 deg (Lat.)
2-9 TECU <24 hours daily 100%
GovernanceTheIGShasbeenproactiveinadvancingitsorganizationandmanagement.TheIGShastakenthese
actions,amongothers,toimprovegovernanceandorganizationalperformance:
WorkingGroupchartersandmembershipAllWorkingGroupchartersandmembershiprostershavebeenreviewedforrelevancyandtoassuretheappropriatetechnicalexpertsremaininvolved.WorkingGroupsarealsonowinvitedtogiveupdatesontheirrespectiveworkshoprecommendationsatregularAssociateMemberOpenMeetings,heldatleastoncebetweenworkshops.AssociateMembershipRosterTheprocessforselectingassociatemembershasbeenreviewedandupdatedbytheIGSGoverningBoard,resultingintheformationoftheAssociateMembershipCommittee.Theconstituencyofassociatemembersisnowreviewedcontinuouslythroughouttheyearonacase-by-casebasis.PerformanceBenchmarkandRevisedStrategicPlanThroughoutmid-2016,theCentralBureauledthedevelopmentanddistributionofstrategicplanning-themedsurveystoboththeIGScommunityaswellasthebroaderIGSstakeholdercommunity.FeedbackwascollectedandanalyzedbytheCBandGBduringthestrategicplandevelopmentprocess,andusedtoshapethegoalsandobjectivesofthe2017StrategicPlan.
ExternalCoordinationTheIGScoordinatesextensivelywithmanyexternalorganizationstopromotetheIGSanddevelopkey
partnershipswithparticipantsandusers:
InternationalAssociationofGeodesy/GlobalGeodeticObservingSystem(IAG/GGOS)TheIGScoordinatesextensivelywithGGOS,includingmembershipoftheCoordinatingBoard,Consortium,SciencePanelandwithintheBureaus.AsaserviceoftheIAG,IGSalsocoordinateswiththeIAGanditsadministration.UnitedNationsOfficeforOuterSpaceAffairs(UNOOSA)InternationalCommitteeonGNSS(ICG)TheICGWorkingGroupDonReferenceFrames,TimingandApplicationsisco-chairedbytheIGSCBDirector,asistheInternationalGNSSMonitoringandAssessmentSystem(IGMAS)TaskForce.TheannualICGMeetingistypicallyattendedbyseveralIGSparticipants.SignificantprogresswasmadeinsupportingthedevelopmentofacooperativeplanwiththeICGtomonitorperformanceandinteroperabilitymetricsbetweenthedifferentGNSSs,whichisnowembodiedbyajointIGS-ICGWorkingGrouponMonitoringandAssessment.
UnitedNationsGGIMSub-CommitteeonGeodesy(formerlyGlobalGeodeticReferenceFrameWorkingGroup)AtthemostrecentsessionoftheGGIMinNewYork(August2017),theworkinggroupwasofficiallyestablishedasapermanentSub-CommitteeonGeodesy,toprovidestabilityandlong-termplanningfortheGlobalGeodeticReferenceFrame(GGRF).Previously,theCommitteeofExpertsalsoendorsedtheGGRFRoadmap,whichaddresseseachofthekeyareasofactiondescribedintheoperationalparagraphsofthe2015UNGeneralAssemblyresolution.TheseeffortsareanticipatedtoopenadditionalavenuesforinternationalcooperationfortheIGSandgeodesyingeneral.Formoreinformation,pleasevisittheUN-GGIMwebsite:http://ggim.un.org/UN_GGIM_wg1.html.InternationalEarthRotationandReferenceSystemsService(IERS)IGSandIERShavecontinuedtoextensivelycooperateintherealizationofITRF,aswellasreciprocallyparticipatingoneachother’sboards.RadioTechnicalCommissionforMaritimeServices,SubcommitteeonDifferentialGNSS(RTCM-SC104)TheIGSholdsvotingmembershiponthisinternationalstandardsorganizationforDifferentialGNSS,andchairstheRINEXWG.
InternationalFederationofSurveyors(FIG)FIGrepresentsthesinglelargestusercommunityofIGSproducts,andisalsoapotentialchannelforextendingtheIGSnetwork.IGSandFIGarecoordinatingtoreachouttousers,toconductjointworkshops,aswellastoadvocateforprecisiongeodesywithinorganizationssuchastheICG.RegionalReferenceFramesTheIGScoordinatesextensivelyatmultiplelevelswithregionalreferenceframeactivities,suchasAFREF,SIRGAS,APREF,NAREF,andEUREF.SeaLevelActivitiesThroughtheTideGaugeWorkingGroup,IGSparticipateswithintheGlobalSeaLevelObservingSystem(GLOSS)topreciselylocatetidegaugeswithintheITRF.Additionally,IGShasengagedwithmanyusercommunitiesrepresentingdifferentregionsanddisciplinesbyparticipatinginscientificworkshopsandconferenceswithpresentationsandchairingofsessions.Examplesofconferenceandworkshopsattendedinclude:InternationalCouncilofScience/WorldDataSystem(WDS),theAmericanGeophysicalUnion(AGU)andEuropeanGeosciencesUnion(EGU),theInternationalUnionofGeodesyandGeophysics(IUGG),theInternationalAssociationofGeodesy(IAG),theAsiaOceaniaGeosciencesSociety,theU.S.InstituteofNavigation,theChinaSatelliteNavigationConference,theColloquiumonScientificApplicationsofGalileo,andothers.
WorkingGroupandProjectHighlightsAdoptionoftheNewIGS14/igs14.atxFramework TheIGSadoptedanewreferenceframe,calledIGS14,on29January2017(GPSWeek1934).Atthesametime,anupdatedsetofsatelliteandgroundantennacalibrations,igs14.atx,wasimplemented.IGS14isthelatestinaseriesofGNSSreferenceframesadoptedbytheIGS.ThesereferenceframesformthebasisoftheIGSproducts,andarederivedfromeachnewversionoftheInternationalTerrestrialReferenceFrame.UpdatingtoIGS14willalignIGSproductstoITRF2014,andincreaseprecisionofthatalignmentbyintegratingadditionalavailablereferenceframestationswithmorepreciseandup-to-datecoordinates.Formoreinformation,pleasesee[IGSMAIL-7399]“UpcomingswitchtoIGS14/igs14.atx.”and“IGS14/igs14.atx:anewframeworkfortheIGSproducts.”CoincidentwiththeIGS14ReferenceFramerelease,IGSadoptedantennacalibrationupdatesinigs14.atx.Theseupdatesincluderobotcalibrationsforadditionalgroundantennatypes,increasingthe
percentageofgroundstationsintheIGSnetworkwithabsolutecalibrationstoover90%.Thiswillresultinincreasedcoordinateaccuracyforstationsequippedwiththeseantennas.SINEXandANTEXfiles,aswellasnetworkmaps,post-seismicdeformationmodels,andoffsetsareavailablefordownloadviaftpfromInstitutNationaldel’InformationGéographiqueetForestière(NationalInstituteofGeographicandForestryInformation,IGN)andÉcoleNationaledesSciencesGéographiques(NationalSchoolofGeographicSciences,ENSGReprocessingCampaigns:repro2FollowingthefirstreprocessingcampaignperformedbytheIGSin2008,asecondreprocessingcampaign(repro2)wasfinalizedin2015.NinedifferentACsreanalyzedthehistoryofGNSSdatacollectedbyaglobaltrackingnetworkbackto1994usingthelatestavailablemodelsandmethodology.BesidessupplyinganimprovedconsistentsetofGNSSgeodeticproducts,onemajorgoaloftherepro2campaignwastoprovidetheIGSinputtothelatestreleaseoftheInternationalTerrestrialReferenceFrame(ITRF2014).TheindividualACproductswerecombinedintoofficialIGSrepro2productscalled"ig2".Resultsfromtherepro2terrestrialframecombinationsaredescribedinRebischungetal.(2016;https://doi.org/10.1007/s00190-016-0897-6),whileresultsfromtherepro2orbitandclockcombinationsaresummarizedinIGSMAIL-7411(https://igscb.jpl.nasa.gov/pipermail/igsmail/2017/008601.html).Troposphererepro2resultsarecurrentlybeingprocessedandevaluated.Multi-GNSSGlobalExperiment(MGEX)Inthebeginningof2016,thestatusoftheMulti-GNSSExperiment(MGEX)oftheIGSwaschangedtoaPilotProjectbytheIGSGoverningBoard.In2016,thenumberofIGSmulti-GNSSstationsincreasedfromalmost130toabout180,seeFigure1.Abouthalfofthestationsalsoprovidereal-timestreams,mainlyviathededicatedMGEXcaster(http://mgex.igs-ip.net/)butalsoviatheIGS-IPcaster(http://igs-ip.net).BothcastersareoperatedbyBKGandprovidethereal-timestreamsindifferentversionsoftheRTCM-3MSMformat.Sixanalysiscenters(ACs)contributeorbitandclockproductstoMGEX:CNES,CODE,GFZ,JAXA,TUM,andWuhanUniversity.MGEXincludesthenewGPSsignals,newRussianGLONASSsignals,theJapaneseQZSS,theChineseBeiDou,andtheEuropeanUnion’sGalileo.
Real-TimeServiceTheIGS-RTSisbasedonaglobalnetworkofIGSstationsprovidingdatastreamstotheRTSobservationbroadcasters.ThereareseveralobservationbroadcastersinoperationincludingthefirstlevelglobalcastersatBKG,CDDISandIGSCentralBureau.ThereareeightrealtimeAnalysisCentres(AC)whichusedifferentsoftwarepackagestocomputeepoch-wiseorbitandclockproducts.ThelargenumberofACsensuresahighredundancyoftheserviceontheonehandandastrongqualitycontrol
Thankstothecontributionsfromalargenumberofpartners,theIGSRTSoperatesadensehighquality
realtimeGNSSnetwork.TheobservationdataisusedtoderiveorbitandclockproductswhichallowuserPPPatdecimeteraccuracy.Alimitationistheconvergencetimeofabout30minutesandthelatencyofthecombinedproductsof20-30s.TheIGSRTSensuresopenaccesstoitsdataandproductsandsupportsopenstandardsanddataformats.DataandproductsareprovidedviaTCP/IPconnections.Therangeofapplicationsisfocusedonscientificandeducationaltopics,suchaspositioning,navigationandtiming,Earthobservationsandresearch;andotherapplicationsthatbenefitthescientificcommunityandsociety.
InfrastructureImprovements<<Nachohaspromisedtoprovideanupdate>>TheInfrastructureCommittee(IC)hasfocusedonimprovingtheIGSnetwork,aswellasplanningthechangeoveroftheIGSinfrastructuretosupportMulti-GNSSandreal-timeefforts,whilemaintainingintegrityofcoreproducts.TheIChasledeffortstorevisetheIGSsiteguidelinestopromoteproperpracticeinoperatingGNSSstations.Themostrecentrevisionin2012addednewproceduresforupgradingstationequipmentdesignedtominimizedisruptiontotheIGSreferenceframe,aswelloperatingstandardsforstationsparticipatingwithintheReal-timeService.TheIChasalsoledanexperimenttoassesstheeffectsof21IGSstationsthatareco-locatedwithSLRorVLBIsiteswhereradomeshavenotbeencalibratedtoIGSstandards.Thiswillaidinmappinganydiscontinuitiesthatmayariseasequipmentisupgradedatthesestations.Analysisiscurrentlyinprogressforanumberoftheparticipatingstations.DataCenterCoordinationDuringthereportingperiod,theIGSDataCenterWorkingGroup(DCWG)workedwiththeInfrastructureCommittee(IC)tointegratemulti-GNSSdatainRINEXVersion3formatintotheoperationaldirectorystructureattheGlobalDataCentersinordertopromotetheuseofmulti-GNSSdataandthenewRINEXformat.TheWGalsocoordinatedasitemetadataactivityformanagingtheinformationcontainedinIGSsitelogsandtopromotetheuseoftheGeodesyMLapplicationschemaformanagingGNSSsitemetadataingeneral.ReceiverIndependentExchangeFormat(RINEX)TheRINEXWorkingGrouphasassumedleadershipinmaintenanceandfurtherdevelopmentoftheRINEXdataexchangestandard,incooperationwithRTCM-SC104,andhasledtherecentreleaseofRINEX3.03.TheRINEXWorkingGrouphasworkedincooperationwiththeICtoprepareaplantotransitionfromRINEX2.xtoRINEX3.x.Additionally,theRWGhasencouragedandsupportedthedevelopmentofopensoftwaretoolsforRINEX3.xdatahandlingandqualitycontrol.TideGaugeBenchmarkMonitoringTheTideGaugeBenchmarkMonitoringWorkingGroup(TIGA)oftheIGScontinuesitssupportforclimateandsealevelrelatedstudiesandorganizationsconcernedherewith(e.g.,GGOS,OSTST,UNESCO/IOC).TheTIGAWGprovidesverticalgeocentricpositions,verticalmotionanddisplacementsof
GNSSstationsatornearaglobalnetworkoftidegaugesandworkstowardsestablishinglocalgeodetictiesbetweentheGNSSstationsandtidegauges
TIGANetworkoperatorworkswithTideGaugeandGNSSstationoperatorstomakeexistingstationsavailabletoTIGA,amain(ongoing)taskistoupdatethecurrentdatabaseofexistinglocaltiesbetweenGNSSandtidegaugebenchmarks.Bytheendof2016about173localtiesinformationweremadeavailableathttp://www.sonel.org/-Stability-of-the-datums.html?lang=en.ThenumberstationsdirectlycommittedtoTIGAthenumberoftieshasrisento76,with820GNSS@TGstations(with119stationsweredecommissioned).TheTIGA-WGcarriedforwardtheGLOSS-Task“PrioritiesforinstallationofcontinuousGlobalNavigationSatelliteSystem(GNSS)neartotidegauges.ReporttoGlobalSeaLevelObservingSystem(GLOSS)”byKing,M.A.(2014)forthedensificationandextensionoftheTIGAObservingNetworktoGGOS.TheresponsebytheGGOSCoordinatingBoardwasreceivedearly2017.ImprovedSatelliteForceModels <noresponsefromMarekregardingupdate.Pleaseadviseifthefollowingshouldbemodified,orifthissubtopicshouldbedeletedfromthistravaux>>TheSatelliteOrbitandDynamicsWorkingGrouphasdevelopedimprovedsatelliteradiationpressuremodels,whichareavailabletoIGSthroughtheUniversityCollegeLondonwebsite.ThesemodelsareexpectedtoimprovethequalityoftheIGSorbitproductsonceimplementedbytheIGSanalysiscenters.BiasandCalibrationResearchTheBiasandCalibrationWorkingGroupcontinuescoordinatingresearchactivitiesrelatedtobiasretrieval,analysis,andmonitoring.Presently,thegroupisconsideringC1W–C1C,C2W–C2C,andC1W–C2Wdifferentialcodebiases(DCB).Potentialquarter-cyclebiasesbetweendifferentphaseobservables(specificallybetweenGPSL2WandL2C)areanotherissuetobedealtwith.InthefaceofGPSandGLONASSmodernizationprogramsandupcomingGNSS,suchastheEuropeanGalileoandtheChineseBeiDou,carefultreatmentofmeasurementbiasesinlegacyandnewsignalsbecomesmoreandmorecrucialforcombinedanalysisofmultipleGNSS.In2016and2017,aGNSSbiasreprocessing(forGPS/GLONASS)usingtherecentlyimplementedobservable-specificsignalbias(OSB)parameterizationwascarriedoutatCODEfor1994-2016RINEXdata.Theoutcomesofthisreprocessingeffortaredailynormal-equation(NEQ)filesforGPSandGLONASScodebiasparametersthatareconformtobothglobalionosphereandclockanalysis.
Thecombinationofthesedailybiasresultsintoacoherentlong-term(1994-present)GPS/GLONASSbiasproductisanotherkeyachievement.Suchabiasproductisparticularlyusefulforapplicationswherecalibrationintheabsolutesensearecrucial(e.g.,forGPStiming,oratomicclockcomparisons).Additionally,CODE’sclassicGPSDCBproductandthemostresentGNSSbiasresultsaremadeavailableusingtheBias-SINEXFormatVersion1.00.TroposphereProductThegoaloftheIGSTroposphereWorkingGroupistoimprovetheaccuracyandusabilityofGNSS-derivedtroposphereestimates.Itdoesthisbycoordinating(a)workinggroupprojectsand(b)technicalsessionsattheIGSAnalysisWorkshops.TheWorkingGroupiscurrentlyfocusingon:automatingcomparisonsoftroposphereestimatesobtainedusingdifferentmeasurementoranalysistechniques,standardizationofthetropo_sinexformat,andautomatedAnalysisCenterEstimateComparisons.
Dr.ChristineHackmanchairedtheIGSTWGthroughDecember2015.Dr.SharylByramhaschaireditsincethenandalsooverseesproductionoftheIGSFTEs.IGSFTEsareproducedwithintheUSNOEarthOrientationDepartmentGPSAnalysisDivision,whichalsohoststheUSNOIGSAnalysisCenter.TheUnitedStatesNavalObservatoryproducesIGSFinalTroposphereEstimatesfornearlyallofthestationsoftheIGSnetwork.Each24-hrsiteresultfileprovidesfive-minute-spacedestimatesoftotaltropospherezenithpathdelay(ZPD),north,andeastgradientcomponents,withthegradientcomponentsusedtocompensatefortroposphericasymmetry.
Dailyzenithpathdelayestimatesarebeinggeneratedwithanapproximatethree-weeklatencyforallactiveIGSsites,basedonPrecisePointPositioningtechniques.IGSFinalTroposphereestimatesareusedbyscientistsworldwidetosupportclimate-changeandmeteorologicalstudies,and46.3millionestimatesfilesfromover1000distincthostsweredownloadedin2012alone.IonosphereProductFollowingtheIGSWorkshop2014inPasadena,ionosphericfluctuationmapproductswereestablishedasapilotprojectoftheIGSservice.Thecurrentproductrosterincludes:finalGIM(pleasenotethatGIMsalsoincludeGPSandGLONASSstations’andsatellites’DCBs);rapidGIM;predictedGIMfor1and2daysahead(pilotproduct).Recentkeyaccomplishmentsinclude:
• IGSGlobalionospherepredictedproductsfor1and2daysahead(pilotproduct).ThisnewIGSproductsarecurrentlybasedonpredictedionospheremapspreparedbyUPCandESA.
• IGSGlobalionospheremapswith1hourtimeresolution.ThisnewIGSproductsarecurrentlybasedonionospheremapspreparedbyUPC,ESAandCODE.
• IGSGlobalIonosphereMaps(GIMs)nowincludedifferentialcodebiases(DCBs)forGLONASSsatellites.
• ThepilotphaseofthenewIGSionosphericproduct-TECfluctuationsmaps
MoreInformationForgreaterdetailabouttheaforementionedactivities,efforts,andcomponents,pleaserefertotheIGSTechnicalReports,availablefordownloadontheIGSKnowledgeBase.