chair: zuheir altamimi head of the iers itrf product center
DESCRIPTION
UN-GGIM- 2 nd HLF Session 3 Developing an Effective Global Geodetic Reference Framework and Supporting Location-Based Services. Chair: Zuheir Altamimi Head of the IERS ITRF Product Center Institut National de l’ Information Géographique et Forestière (IGN), France - PowerPoint PPT PresentationTRANSCRIPT
UN-GGIM HLF, Session 3, Doha, February, 2013
UN-GGIM- 2nd HLFSession 3
Developing an Effective Global Geodetic Reference Framework and Supporting
Location-Based Services
Chair: Zuheir AltamimiChair: Zuheir Altamimi
Head of the IERS ITRF Product CenterInstitut National de l’Information Géographique et
Forestière (IGN), France
E-mail: [email protected]
UN-GGIM HLF, Session 3, Doha, February, 2013
• Keynote: Mr. Hansjorg Kutterer, President, Federal Agency for Cartography and Geodesy, Germany
• Panel Discussion:1. Mr. Uzochukwu Okafor, Surveyor General, Namibia
2. Mr. John Dawson, Geospatial Reference Systems, Geoscience Australia, Australia
3. Mr. Alvaro Monett, Executive Secretary, SNIT, Chile
4. Mr. Nasr Al-Sahhaf, Director, Saudi Space Geodesy Center, Saudi Arabia
5. Mr. Stefano Ghielmetti, Director, Institutional Business Development, Trimble Navigation
6. John Dawson: Summary of responses of the geodetic questionnaire
7. Interventions from the floor
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Session 3 Presentations
Exchange Forum, Doha, February, 2013
UN-GGIM Objectives
• The promotion of global geospatial information to address key global challenges & to support improved decision-making;
• At the 2nd Session of the Committee of Experts held in New York in August 2012 nine critical issues were identified, including:– future trends for geospatial information– development of a knowledge base– a global geodetic reference system – a global map for sustainable development
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Exchange Forum, Doha, February, 2013
Background: need for a global terrestrial reference system (1/2)
• Positioning (determination of point positions or coordinates) is fundamental for– Earth science & Earth observation applications– Geospatial activities, navigation, civil engineering, agriculture, … – Disaster management & reconstruction (Earthquake, Tsunami…)
• Coordinates are time dependent– Plate motion --> up to 10 cm/yr– Earthquake dislocation --> up to several meters
• To be truly useful, coordinates are (should be) expressed in a terrestrial reference system
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Exchange Forum, Doha, February, 2013
Background: need for a global terrestrial reference system (2/2)
• Need for a global & unique/standard reference frame --> ensure inter-operability
• GNSS is today’s best tool for positioning :– To support science and societal applications– Low-cost, easy to use, with up to few mm precision
• Need for Continuously Operating GNSS Core Stations, necessary for: – Access to the global reference frame– Variety of other geodetic & geospatial applications
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UN-GGIM HLF, Session 3, Doha, February, 20136
IAG Structure since 2003
Commission 4Positioning and
Applications
Commission 1
Reference Frames
Commission 2
Gravity Field
Commission 3Earth Rotation and
Geodynamics
International Union of Geodesy and Geophysics (IUGG)65 Member Countries (Adhering Bodies), 8 Associations
International Association of Geodesy (IAG)
Executive Committee OfficeCouncil COB
BIPM
IVS PSMSL
IGS
Global Geodetic Observing System (GGOS)
Services:
IGeS
IAS
IDSILRS IDEMSICGEM IBS
BGIIGFSIERS ICET
Inter-Commission Committee on Theory (ICCT)
Bureau
IUGG
http://www.iag-aig.org
Exchange Forum, Doha, February, 2013
The International Terrestrial Reference Frame (ITRF) • Established and maintained by the International Earth
Rotation and Reference Systems Service (IERS)
• Adopted by IAG & IUGG in 1991 & 2007 and by CGPM in 2011 for Earth science & timing applications
• Updated every 3-5 years: ITRF88,…,2000,2005
• Current Version: ITRF2008
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UN-GGIM HLF, Session 3, Doha, February, 2013
Key Points
• GNSS provides high accuracy for positioning applications
• IAG provides the International Terrestrial Reference System (ITRS) on which all GNSS positioning services are based
• Implementation of Regional & National geodetic systems depend & rely on the availability of the ITRF
• Note the progress of the ITRS implementations at the national level that should continue
• Need for UN mandate for the ITRF and its infrastructure ?
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UN-GGIM HLF, Session 3, Doha, February, 2013
• backups
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UN-GGIM HLF, Session 3, Doha, February, 2013 10
What is a Reference Frame in practice? • Earth fixed/centred RF: allows determination of
station location/position as a function of time
• It seems simple, but … we have to deal with:– Relativity theory– Forces acting on the satellite– The atmosphere– Earth rotation– Solid Earth and ocean tides– Tectonic motion – …
Origin, Scale & Orientation
• Station positions and velocities are now determined with mm and mm/yr precision
UN-GGIM HLF, Session 3, Doha, February, 2013
ITRF2008 Network
580 sites (920 stations)
461 Sites North
118 Sites South
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492 IGS/GNSS sites
UN-GGIM HLF, Session 3, Doha, February, 2013
ITRF2008 Site Velocities:time-span > 3 yrs, (σ ~ 0.1 – 1 mm/yr)
509 sites
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UN-GGIM HLF, Session 3, Doha, February, 2013
Access to the ITRF and the IGS role• Any GNSS network can easily be expressed in the ITRF
using IGS products (orbit, clocks, ERP: all expressed in the ITRF)
• IGS/GNSS observations (RINEX files) & Products are publicly available
• IGS products (Orbits, Clocks and Earth Rotation Prameters) to be fixed in regional processing
• Geodetic/mathematical procedure to express a GNSS network in the ITRF is also available
• NMAs have access to scientific software packages
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UN-GGIM HLF, Session 3, Doha, February, 2013
Processed IGS/GNSS sites, since 1994
Time series: Red < 5yrs (118), Blue 5-10yrs (138), Green 10-18yrs (396)
652 sites
UN-GGIM HLF, Session 3, Doha, February, 2013
Regional & National Reference Systems/Frames
• IAG Commission 1 (Reference Frames) ==> Sub-Commission 1.3 (Regional Reference Frames):
– EUREF/Europe: ETRS89
– NAREF/North America: NAD83
– SIRGAS/South America: SIRGAS
– AFREF/Africa
– APREF/Asia & Pacific
– SCAR/Antarctica
• Regional Reference Frames: rely on the ITRF• Many countries have redefined their geodetic
systems to be compatible with/related to ITRF
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UN-GGIM HLF, Session 3, Doha, February, 2013
EUREF Permanent Network (EPN)
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UN-GGIM HLF, Session 3, Doha, February, 2013
AFREF Network
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UN-GGIM HLF, Session 3, Doha, February, 2013
SIRGAS Network
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UN-GGIM HLF, Session 3, Doha, February, 2013
ITRF densification
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ITRF2008 GNSS sites Densification sites
Courtesy Juliette Legrand
UN-GGIM HLF, Session 3, Doha, February, 2013
GNSS associated reference systems/frames
GNSS Ref. System/Frame• GPS (broadcast orbits) WGS84• GPS (precise IGS orbits) ITRS/ITRF• GLONASS PZ-90• GALILEO ITRS/ITRF/GTRF• COMPASS CGCS 2000• QZSS JGS • All are now aligned to the ITRF2008• WGS84 ≈ ITRF at the decimeter level• GTRF ≈ ITRF at the mm level -Position using broadcast ephemerides = 150 cm
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UN-GGIM HLF, Session 3, Doha, February, 2013
Why is a Reference Frame needed? • Precise Orbit Determination for:
– GNSS: Global Navigation Satellite Systems– Other satellite missions: Altimetry, Oceanography,
Gravity
• Earth Sciences Applications – Earth rotation– Tectonic motion and crustal deformation– Glacial Isostatic Adjustment (GIA) (= Post Glacial Rebound)– Mean sea level variations– …
• Geo-referencing & Positioning applications– Navigation: Aviation, Terrestrial, Ocean– Surveying – Positioning
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UN-GGIM HLF, Session 3, Doha, February, 2013 22
Current networks: stations observed in 2011
VLBI SLR
GPS/IGS DORIS
UN-GGIM HLF, Session 3, Doha, February, 2013
VLBI, SLR, DORIS sites & their co-locations with GPS
52324223
UN-GGIM HLF, Session 3, Doha, February, 2013
Space Geodesy Techniques Contributing to the ITRF
• Very Long Baseline Interferometry (VLBI)• Satellite Laser Ranging (SLR)• DORIS• GNSS: GPS, GLONASS, (Future: GALILEO, COMPASS, QZSS)
• ITRF Defining Parameters:– Origin: CoM of the Earth System: defined by SLR
– Scale : Consistent with TCG: defined by VLBI & SLR
– Orientation: Equatorial: Same for all ITRF versions: Currently ensured by mainly GNSS/IGS network
• ITRF Origin & Scale are very critical for science applications, e.g. monitoring of sea level variation
• Science Requirement: ITRF to be stable at 0.1mm/yr level
UN-GGIM HLF, Session 3, Doha, February, 2013
SLR/LLR
DORIS
VLBI
GNSS
DX(GPS,VLBI) = XVLBI - XGPS
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Co-location site• Site where two or more instruments are operating• Surveyed in three dimensions, using classical or GPS geodesy
UN-GGIM HLF, Session 3, Doha, February, 2013 26
ITRF Construction
Time series stacking X V
Velocity equality
Local ties
Combination
ITRF Solution
At co-location sites
DORISGPS
SLRVLBI
DORISGPS
SLRVLBI
Long-term SolutionsIAG Services:IDS IGS ILRS IVS
Station pos & vel& EOPs
UN-GGIM HLF, Session 3, Doha, February, 2013
Eurasia
N. Ameri
ca
Nubia
Som
alia
S. A
mer
ica
Australia
Pacific
Antarctica
Indi
a
Naz
caArabia
Amur
Sund
aCARB
ITRF2008 Plate Motion Model Available for 14 plates
Plate boundaries: Bird (2003) & MORVEL, DeMets et al. (2010)
Altamimi et al., JGR, 2012
UN-GGIM HLF, Session 3, Doha, February, 2013
ITRF Website (itrf.ign.fr)
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UN-GGIM HLF, Session 3, Doha, February, 2013
WGS84 - NGA Stations in ITRF2008
NGA: National Geospatial-Intelligence Agency
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UN-GGIM HLF, Session 3, Doha, February, 2013
ITRF precision (formal errors)
ITRF Accuracy in Origin and Scale~1 cm (ITRF2008) over its time-span
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Positions Velocities
UN-GGIM HLF, Session 3, Doha, February, 2013
Access to the ITRF and the IGS role (1/2)
• How to express a GNSS network in the ITRF using IGS products (orbit, clocks, ERP: all expressed in the ITRF) ?
• Select a reference set of ITRF/IGS stations and collect RINEX data from IGS data centers;
• Process your stations together with ITRF/IGS ones:
• Fix IGS orbits, clocks and ERPs • Eventually, add minimum constraints conditions in
the processing:
= 0
ITRF Your Solution
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UN-GGIM HLF, Session 3, Doha, February, 2013
Access to the ITRF and the IGS role (2/2)
==> Your solution will be expressed in the ITRFyy consistent with IGS orbits
• Propagate official ITRF station positions at the central epoch (tc) of the observations:
• Compare your estimated ITRF station positions to official ITRF values and check for consistency:– Transformation parameters should be zeros
– No outliers: residuals smaller than a certain threshold.
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