Global Geodetic Observing System: Meeting the Requirements of a Global Society on a Changing Planet in 2020 PDF
Preview Global Geodetic Observing System: Meeting the Requirements of a Global Society on a Changing Planet in 2020
Global Geodetic Observing System · Hans-Peter Plag Michael Pearlman Editors Global Geodetic Observing System Meeting the Requirements of a Global Society on a Changing Planet in 2020 123 Editors Dr.Hans-PeterPlag Dr.MichaelPearlman UniversityofNevada,Reno Harvard-Smithsonian NevadaBureauofMines& CenterforAstrophysics Geology&SeismologicalLaboratory 60GardenSt. RenoNV89557 CambridgeMA02138 USA MS16 USA ISBN978-3-642-02686-7 e-ISBN978-3-642-02687-4 DOI10.1007/978-3-642-02687-4 SpringerDordrechtHeidelbergLondonNewYork LibraryofCongressControlNumber:2009932078 (cid:2)c Springer-VerlagBerlinHeidelberg2009 Thisworkissubjecttocopyright.Allrightsarereserved,whetherthewholeorpartofthematerialis concerned,specificallytherightsoftranslation,reprinting,reuseofillustrations,recitation,broadcasting, reproductiononmicrofilmorinanyotherway,andstorageindatabanks.Duplicationofthispublication orpartsthereofispermittedonlyundertheprovisionsoftheGermanCopyrightLawofSeptember9, 1965,initscurrentversion,andpermissionforusemustalwaysbeobtainedfromSpringer.Violations areliabletoprosecutionundertheGermanCopyrightLaw. Theuseofgeneraldescriptivenames,registerednames,trademarks,etc.inthispublicationdoesnot imply,evenintheabsenceofaspecificstatement,thatsuchnamesareexemptfromtherelevantprotective lawsandregulationsandthereforefreeforgeneraluse. Coverdesign:deblik Printedonacid-freepaper SpringerispartofSpringerScience+BusinessMedia(www.springer.com) Foreword TheGlobalGeodeticObservingSystem(GGOS)hasbeenestablishedbytheInter- nationalAssociationofGeodesy(IAG)inordertointegratethethreefundamental areas of geodesy, so as to monitor geodetic parameters and their temporal varia- tions, in a global reference frame with a target relative accuracy of 10−9 or bet- ter. These areas, often called ‘pillars’, deal with the determination and evolution of(a)theEarth’sgeometry(topography,bathymetry,icesurface,sealevel),(b)the Earth’srotationandorientation(polarmotion,rotationrate,nutation,etc.),and(c) the Earth’s gravity field (gravity, geoid). Therefore, Earth Observation on a global scale is at the heart of GGOS’s activities, which contributes to Global Change re- searchthroughthemonitoring,aswellasthemodeling,ofdynamicEarthprocesses suchas,forexample,massandangularmomentumexchanges,masstransportand oceancirculation,andchangesinsea,landandicesurfaces.Toachievesuchanam- bitiousgoal,GGOSreliesonanintegratednetworkofcurrentandfutureterrestrial, airborneandsatellitesystemsandtechnologies.Theseinclude:variouspositioning, navigation, remote sensing and dedicated gravity and altimetry satellite missions; global ground networks of VLBI, SLR, DORIS, GNSS and absolute and relative gravity stations; and airborne gravity, mapping and remote sensing systems. The optimalassimilationofsuchheterogeneousobservationsintomodelsofgeodynam- ics,oceanography,hydrology,glaciology,andweatherandclimate,willbedoneby interdisciplinaryteamsofresearchersfromgeodesyandothersciences,andthrough thecoordinatedworkofallIAGServicesandCommissions.Naturally,addressing problemsofsuchlargescaleandcomplexityrequiresinternationaleffortandcom- mitment.Suchinitiativesarealreadyunderway(GEO,GEOSS),andGGOSrepre- sents IAG, and geodesy in general, in all of them, and provides the scientific and infrastructurecontributionofgeodesytotheEarthsciences. ThescienceandapplicationsthatGGOSaddresseshaveimportantimplications forthewell-beingoftheglobalsociety.Inaneraofeconomicuncertaintyandrapid environmental change it is imperative that action be taken to minimize risks from natural hazards, climate change, sea level rise, etc., to develop forecasting mod- elsforoceansandweather,andearlywarningsystemsforseverestorms,tsunamis, and other hazards, and to manage our natural resources and our environment in a v vi Foreword sustainable manner. To understand the Earth processes responsible for the afore- mentionedhazardsrequirescontinuousmonitoringcampaignsoverlongperiodsof time,aswellasnovelmodelingoftheobservedchangeswithtime.Inotherwords, wecannolongerspeakofgeodesyinthreedimensions;wehaveenteredanewand excitingeraoffour-dimensionalgeodesy,inwhichmoderngeodesyhasbecomean indispensiblecontributortotheunderstandingofSystem-Earthanditsevolutionin time.IAGiswell-positionedandproudtobeabletocontributetothisinternational effort through the work of GGOS, and therefore considers GGOS as its flagship Component. TheGGOS2020documentdescribesthechallenges,science,technology,appli- cations,strategies,futureplansandexpectedcontributionsofIAGandGGOStothe Earthsciencesthroughthenextdecade.Itcontainsthecollectiveworkoveraperiod ofseveralyearsofmanyindividualsandorganizations toomanytolisthere without whomthisvolumewouldnothavebeenpossible.TheIAG,andIpersonally,express oursinceregratitudetoeachoneofthem.Manythanksareduetotheauthorsofthe variouschaptersandtheeditorsofthisvolume,andinparticulartoHans-PeterPlag, forthecountlesshourshehasdevotedtowriting,editingandcoordinating,andhis enthusiasticdedicationtotheproject. Calgary,February2009 Prof.MichaelG.Sideris President,InternationalAssociationofGeodesy Preface Aboutthisbook Background This book describes the scientific rationale and the specifications for the Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG) in terms of concepts, conventions, infrastructure and services, that would meetfuturerequirementsofaglobalcommunityfacingincreasinglychallengeson achangingplanet.Withthisinmind,thedocumentprovidesthebasisforthefurther development of GGOS over the next decade and beyond. GGOS is built upon the basisprovidedbytheexistingServicesandCommissionsofIAGandisoneofthe majorIAGcomponents.Inordertomaximizethebenefitstousersoftheconsider- ableinfrastructureandresourcesavailabletotheseServices,theconceptforGGOS andthestrategyforitsdevelopmentandimplementationrequirecarefulconsidera- tionsofthefutureneedsofsocietyforgeodeticobservationsandservices. Improvements to the International Terrestrial Reference Frame (ITRF) and the availability of geodetic observations of changes in Earth’s shape, gravity field and rotationoverthelastfewdecadeshavebeenamajordriverofscientificdiscovery. Furtherimprovementcanbeexpectedtoleadtomoreexcitingdiscoveries,particu- larlyincombinationwithemergingnewobservationtechnologiesformonitoringthe variabilityoftheEarth’sgravityfieldandsurfacedeformations.Inabroadersense, the geodetic reference frames and observations have contributed to a transition of manyprocessesinsocietyandareexpectedtocontinuetodoso.Thisgreatpoten- tialforscientificprogressinsupportofsocietalneedsassociatedwithanimproved geodeticobservingsystemmotivatedtheprocessthatledtothisbook. ThecontextforthisbookistheincreasingsocietalandscientificneedforEarth observations, and their dependence on an appropriate geodetic foundation as well asacontinuousseriesofgeodeticobservations.Thereisagrowingawarenessthat sustainabledevelopment,whichistheagreed-uponleadingprincipleandgoalofthe globalcommunity,cannotbeachievedwithoutsufficientknowledgeaboutthestate, vii viii Preface trendsandprocessesintheEarthsystem.Thisismanifestedintheestablishmentof theGrouponEarthObservations(GEO)withcurrentlyabout75membercountries. The main purpose of GEO is to facilitate the implementation of the Global Earth ObservationSystemofSystems(GEOSS),withthevisionforthissystemtorealize a future wherein decisions and actions for the benefit of humankind are informed by coordinated, comprehensive and sustained Earth observations and information (GEO,2005a). GeodesyprovidesthefoundationformostEarthobservationsaswellascrucial observations of changes in the Earth’s geometry, gravity field, and rotation, which areallrelatedtomasstransportintheEarthsystemandthesystemdynamics.There- fore, geodesy is crucial for meeting many of the requirements for observations of global change and observations supporting studies of the Earth system. Providing thebasisforprecisepositioningandnavigation,geodesyisalsocruciallysupporting orenablingmanyactivitiesandprocessesinamodernsociety. Realizingtheimportanceofthegeodeticreferenceframeandthecontributionof geodesytoEarthobservations,GEOhasincludedaspecificTaskAR-07-03“Global geodetic reference frames” in its Work Plan 2007-2009 and and as Sub-Task DA- 09-2cintheWorkPlan2009-2011.UnderstandingtherequirementsforGGOSisa centralgoalofthistask.ThepresentbookprovidesthisinputtotheGEOTask. ThedevelopmentofEarthobservationstakesplaceinacontextwhereaconsid- erable fraction of the funding for Earth observation infrastructure and research is allocated in response to major natural and anthropogenic disasters without a suffi- cientlywelldevelopedcoreinfrastructurestableovertime.Manysatellitemissions areresearch-oriented,whereasoperationalmonitoringofmanykeyindicatorsofthe Earthsystemisinsufficientlyimplemented(GEO,2005b). In geodesy, this situation is not much different. Current limitations in funding, oftenwithalackofappreciationofdecisionmakersoftheimportanceofthegeode- ticobservingsystemforEarthobservationsandsocietyatlarge,hasledtotheglobal geodetic community seeking yo provide better products and services based on in- crementalimprovementstothesysteminanoverallframeworkthatseverelylimits theoptionsforsuchimprovements. Scope Theadventofthespace-geodetictechniques,andtherapidimprovementandgrowth ofcommunicationtechniquesandcapacities,haslaunchedarevolutioninthefield ofappliedandglobalgeodesy.Moreover,geodeticimagingincreasinglygainsim- portance,andtheintegrationofthenewtechniquesandmethodsintothetraditional point-basedapproachofgeodesyposesamajorchallenge.Therefore,itistimelyto assessthoroughlytheuserrequirementsforthegeodeticobservationsandproducts, andbasedontheserequirementstodesignanoptimalfuturesystem,whichmakes use of the maturing space-geodetic techniques as well as emerging imaging tech- niques.Inordertodoso,theauthorsforthecontributionscollectedinthisbookhad Preface ix totakeafreshapproachtotheproblem,notonlywithrespecttotheinfrastructure but even more so concerning the underlying concepts, including the conventional approachtogeodeticreferenceframes.Someoftheconceptsdescribedorproposed here contradict current “best practices” and time will tell whether these new con- ceptswillfacilitatesignificantprogressorwhethertheywillhavetobemodified. The authors of the contributions collected in the book do not attempt to assess currentsystems,concepts,productsandservices,butrathertakeanewlookatthe problem of building a geodetic observing system. The starting point is a rigorous review of the societal and scientific problems that require geodetic observations for their solution. This analysis leads to a set of general user requirements. These requirementsarethen,inasecondstep,usedtoderivefunctionalsystemspecifica- tions.Athirdstepfocusesonthedesignofasystemthatwouldmeetthesespecifi- cations. Collectively,thechaptersofthisbookprovide: (1)adescriptionofthescientificandsocietalproblems,aswellaspracticalapplica- tionsthatbenefitfromgeodeticobservations,servicesandproducts; (2)acomprehensiveoverviewoftheuserrequirementsforgeodeticobservationsand products as derived from a broad range of societal benefit areas and scientific requirements; (3)thefunctionalspecificationsforageodeticobservingsystemcapableofmeeting theuserrequirements; (4)a concept for future realizations of a (terrestrial) reference system able to meet theuserrequirements; (5)the design of a system capable of addressing the functional specifications, in termsofconventions,techniques,infrastructure,anddataanalysis;and (6)considerationsandrecommendationsforthesystemimplementation. Theanticipatedaudience This book is a comprehensive document describing the background rationale for GGOS.ItwaswrittenbyateamofChapterLeadAuthors,eachsupportedbyChap- terWritingTeams.Besidesincludinggeodeticexpertsinallrelevantfields,thechap- terteamsalsoincludeexpertsfromotherfieldsofEarthsciencesandEarthobserva- tions.Thisbookservestwopurposes:(1)toinformusersofEarthobservations(in particular,GEO)ofthepotentialofGGOS,and(2)toensurethattheGGOScom- munityisawareoftheusers’needsandrequirementssoastointegrateGGOSinto GEOSS for maximum mutual benefit. Thus, this book seeks to facilitate commu- nicationacrossseveralsectoralanddisciplineboundaries,includingthosebetween geodesyandotherEarthsciences,betweenscientistsandoperationalagencies,and betweenGGOSandGEOSS. x Preface Documentsconsulted Geodesy has a long tradition of assessing the requirements of society and of pro- jecting these into future developments of the geodetic techniques and observing systems.Thisbookcontinuesthistradition,anditthereforebenefitedfromanum- berofreportsmadeavailableoverthelastfourdecades.Thesereportsinclude,but are not limited to, the “Williamstown Report” (Kaula, 1970), the “Erice Report” (Mueller&Zerbini,1989),thereportongeodesyin2000preparedbytheU.S.Na- tionalResearchCouncilin1990(CommissiononPhysicalSciences,Mathematics, and Applications, 1990), the “Coolfont Reports” (NASA, 1991a,b,c), the gravity reportbytheU.S.NationalResearchCouncil(CommissiononGeosciences&Re- sources, 1997), the Living on a Restless Planet report of the Solid Earth Science Working Group of NASA (Solomon & the Solid Earth Science Working Group, 2002),thereportofanInSARWorkshop(Zebker,2005),andtherecentESAdocu- mentTheChangingEarth(Battrick,2006). In the frame of the Integrated Global Observing Strategy - Partnership (IGOS- P) and GEO, several reports documented the needs for Earth observations in sev- eral societally relevant fields. Examples are the documents of GEO, such as GEO (2005a,b), the IGOS-P Theme reports (e.g., IGOS-P Ocean Theme Team, 2001; Lawford&theWaterThemeTeam,2004;Marsh&theGeohazardsThemeTeam, 2004; Townshend & the IGOL Writing Team, 2004; Key & the IGOS-Cryo Writ- ing Team, 2004), as well as reports produced by the various United Nations (UN) Agenciesandprograms.ThelatterincludeinparticulartherecentUNWaterreport (UnitedNations,2006). Inanumberofrecentreports,userrequirementsforgeodeticobservationshave beenconsidered.Someofthesereportsarefocusedonnationaldevelopments(e.g., Williams et al., 2005), improvements to the current situations (e.g., Plag, 2006a), orsingletechnologicalaspects(suchasNielletal.,2006).Ofdirectimportancefor thisbookarethedocumentsandpublicationsproducedbyIAGscientistsandteams focusingonGGOS,namelythepapersinRummeletal.(2000)andtheGGOSIm- plementation Plan (Beutler et al., 2005). A considerable number of recent studies concerningrelevantEarthsystemprocessesandthegeodeticobservationsrequired tostudytheseprocesseshavebeenproduced.ExamplesaretheUNAVCOreporton solidEarthscience(UNAVCO,1998),theGermanreportonmassmovements(Ilk etal.,2005),andtheU.S.reportonInSAR(InSARWorkingGroup,2005).Inaddi- tiontothesereport,anumberofsciencereportsfromrelatedfieldshavebeencon- sulted,suchasthereportonearthquakesciencebytheNationalResearchCouncil (BoardonEarthSciencesandResources,2003),theNASAstudyonaglobalearth- quake satellite system (Raymond et al., 2003), and the National Research Council DecadalSurvey(NationalResearchCouncil,2007). Reno,Boston, Hans-PeterPlag March2009 MichaelPearlman
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