IGS Overview

Ruth Neilan

IGS Central Bureau at JPLPasadena, California

USA

Content

• Mission & History• Organization of the IGS

– Key Components– Working Groups– Pilot Projects– Applications

• Resources, IGS CB Information System

In Support of Science

• The accuracies of the IGS data and products are to be sufficient to support scientific requirements– Access to and continued improvement of the ITRF

(International Terrestrial Reference Frame)• Station position and velocities• Monitoring Earth rotation parameters

– Monitoring deformation of the solid Earth and hydrosphere variations

– Precise time transfer– Scientific satellite orbit determination, LEO’s – Ionospheric monitoring and research– Atmospheric applications - ground and space based for

climate research, eventually weather forecasting

Historical Perspective

Key factors in formation of IGS • All geodynamics and geodetic organizations realized

the potential of GPS by early 90’s• Motivating goal: Millimeter positioning in support of

science anywhere in the world• Not one agency can nor should assume the capital

investment & recurring operations costs for the entire infrastructure

• Join with key international partners to form federation, define cooperation, set standards, science quality driven

• IGS History documented in Annual Report Series (1994)

Organization of the International GPS Service

NAVSTAR GPS Satellites

GPS Stations

Telephone - Modem, Radio Links

INTERNET

SATELLITE LINK

Operational & Regional Data Centers

Global Data Centers

Analysis Centers

Analysis Center Coordinator

Central BureauManagement, Network Coordinator,Central Bureau Information System

USERSPractical, Custom,

Commercial, Governments,...

INTERNATIONAL GOVERNING BOARD

Regional Network Associate Analysis Centers

Global Network Associate Analysis Centers

ORGANIZATION OF THE INTERNATIONAL GPS SERVICE

IGS Projects and Working Groups

Reference Frame DensificationPrecise Time Transfer

Low Earth OrbitersIonosphereAtmosphere

Sea LevelGLONASS Pilot Service Project

Organization of the IGS

• The IGS accomplishes its mission through the following components:– Network of tracking stations– Data Centers– Analysis Centers and Associate Analysis Centers– Analysis Center Coordinator– Reference Frame Coordinator– Working Groups and Pilot Projects– Central Bureau– Governing Board

IGS Extended Network

IGS Global Tracking Stations

Data Centers of the IGS

Data Centers have three categories (see IGS Data Center Presentation)

• Operational Centers have direct contact with the stations

• Regional Centers store all data from a geographic region, some for a special application

• Global Data Centers (GDC) are the main interface with Analysis Centers and Users, store all data used by Analysis Centers and all IGS products– Crustal Dynamics Data Information System– Institut Geographique National– Scripps Institution of Oceanography

Analysis Centers of the IGS

• Analysis Centers have two categories:– Analysis Centers produce daily products on a

continuous basis– Associate Analysis Centers produce unique products

such as station coordinates and velocities, tropospheric information; ionosphere information; they may facilitate distributed processing, analyze dense regional networks, combine network solutions, etc.

• Global Network Associate Analysis Centers (GNAAC)• Regional Network Associate Analysis Centers

(RNAAC)• Products and applications of the ACs, see IGS Product

presentation.

IGS Analysis Centers

• Analysis Centers– Astronomical Institute University of Bern, Switzerland -

CODE– European Space Operations Center / European Space

Agency, Germany - ESOC– FLINN Analysis Center, Jet Propulsion Laboratory, USA-

JPL– GeoForschungsZentrum, Germany - GFZ– Geosciences Lab, National Geodetic Survey, USA- NGS– Natural Resources Canada, Canada- NRCAN (EMR)– Scripps Institution of Oceanography, USA – SIO– US Naval Observatory, USA - USNO

• Analysis Coordinator: Tim Springer, University of Bern, formerly Jan Kouba, Natural Resources Canada

IGS Central Bureau

• The Central Bureau is responsible for general management of the IGS and acts as the executive arm of the Governing Board. The CB is located at NASA’s Jet Propulsion Laboratory.

• The primary functions of the CB are to:– Coordinate and manage IGS activities– IGS Network Coordination responsibilities formalized in

1998– Establish and promote compliance to IGS network

standards– Monitor network operations and quality assurance of data– Develop and operate the Central Bureau Information

System (CBIS) website– Act as day-to-day liaison with external agencies worldwide

IGS Governing Board

MEMBER INSTITUTION & COUNTRY FUNCTIONS TERM*(current: 4 years)

• Christoph Reigber GeoForschungsZentrum, Germany Chair, Appointed (IGS) 1999-2002• Gerhard Beutler University of Bern, Switzerland Appointed (IAG)

---• Mike Bevis University of Hawaii, USA Appointed (IGS) 1998-2001• Geoff Blewitt University of Nevada, Reno Analysis Center Representative 1998-2001• Claude Boucher Institut Geographique National, ITRF France IERS Representative   ---• Carine Bruyninx Royal Observatory, Belgium IGS Representative to IERS  2000-2003• John Dow European Operations Center, Germany Network Representative 2000-2003• Bjorn Engen Norwegian Mapping Authority Network Representative 1998-2001• Joachim Feltens European Operations Center, Germany Ionosphere Working Group Chair 1999-2000• Remi Ferland Natural Resources Canada IGS Reference Frame Coordinator 1999-2000• Gerd Gendt GeoForschungZentrum Potsdam, Germany Troposphere Working Group Chair 1999-2000• Tom Herring Massachusetts Institute of Technology IAG Representative ---• John Manning Australian Survey and Land Information Group Appointed (IGS)

2000-2003• Ruth Neilan IGSCB, Jet Propulsion Laboratory, USA Director of Central Bureau ---• Carey Noll Goddard Space Flight Center, USA Data Center Representative 1998-2001• Paul Paquet Royal Observatory of Belgium FAGS Representative ---• Jim Ray U.S. Naval Observatory, USA Precise Time Transfer Project, Chair 1999-2000• Markus Rothacher Technical University Munich, Germany Analysis Representative 2000-2003• Robert Serafin Natl. Center for Atmospheric Research, USA Appointed (IGS)

1998-2001• Jim Slater Natl. Imagery and Mapping Agency USA International GLONASS Pilot Project, Chair 2000-2002• Tim Springer University of Bern, Switzerland Analysis Center Coordinator 1999-2002• Michael Watkins Jet Propulsion Laboratory, USA Low Earth Orbiter Working Group Chair 1999-2000• James Zumberge Jet Propulsion Laboratory, USA Analysis Center Representative

2000-2003 • Angelyn Moore IGSCB, Jet Propulsion Laboratory, USA Secretariat ---

Contributing Organizations & People

• Over 80 Contributing Organizations

• 108 Associate Members

• More than 1200 Corresponding Members

• See Resource Sheets (Pages 4 – 7) for details

Contributing Organizations

FOMI FOMI Satellite Geodetic Observatory, Budapest, Hungary

GSD Geodetic Survey Division, NRCan, Canada

GFZ GeoForschungsZentrum, Potsdam, Germany

GSI Geographical Survey Institute, Tsukuba, Japan

GIUA Geophysical Institute, University of Alaska, Fairbanks, AK, USA

GRDL Geosciences Research and Development Laboratory, NOAA, Silver Spring, MD, USA

GSFC Goddard Space Flight Center / NASA, USA

HRAO Hartebeesthoek Radio Astronomy Observatory, South Africa

IRIS Incorporated Research Institutions for Seismology, USA

ICC Institut Cartografic de Catalunya, Barcelona, Spain

IGN Institut Geographique National, Paris, France

IMVP Institute for Metrology of Time and Space, GP VNIIFTRI, Mendeleevo, Russia

ISAS Institute for Space and Astronautic Science, Sagamihara, Japan

ISRO Institute for Space Research Observatory, Graz, Austria

IAA Institute of Applied Astronomy, St. Petersburg , Russia

INASAN Institute of Astronomy, Russian Academy of Sciences, Moscow, Russia

IESAS Institute of Earth Sciences, Academia Sinica, TaiwanIGGA-WUT Institute of Geodesy & Geodetical Astronomy, Warsaw

University of Technology, PolandIGNS Institute of Geological and Nuclear Sciences, New

ZealandIBGE Instituto Brasileiro de Geografia de Estatistica, BrazilINEGI Instituto Nacional de Estadistica Geografia e

Informatica, Aguascaliente, MexicoINGEOMINAS Instituto Nacional de Invetigaciones Geologico

Mineras (INGEOMINAS), Bogota, ColombiaINPE Instituto Nacional de Pesquisas Espaciais, Brazil

AWI Alfred Wegener Institute, Germany

AIUB Astronomical Institute, University of Bern, Switzerland

AUSLIG Australian Survey and Land Information Group, Australia

BAKO Bako Surtanal, Indonesia

BKG Bundesamt fuer Kartographie und Geodaesie, Germany

BFL Bundesamt für Landestopographie (Federal Topography), Switzerland

BIPM Bureau International des Poids et Mesures

CSR Center for Space Research, University of Texas at Austin, USA

CNES Centre National de Etudes, Toulouse, France

CEE Centro de Estudios Espaciales, Chile

CICESE Centro de Investigación Científica y de Educación Superior de Ensenada, Mexico

CAS Chinese Academy of Sciences, China

KAO-CAS Chinese Academy of Sciences, Kunming Astonomical Observatory, China

CSB China Seismological Bureau

CDDIS Crustal Dynamics Data Information System, GSFC/NASA, USA

CMMACS CSIR Centre for Mathematical Modeling and Computer Simulation, Bangalore, India

DUT Delft University of Technology, Netherlands

DITTT Department of Land, Noumea, New Caledonia

DLR/DFD Deutsche Forschungsanstalt für Luft-und Raumfahrt e.V., Neustrelitz, Germany

ERI Earthquake Research Institute, University of Tokyo, Japan

VS NIIFTRI East-Siberian Research Institute for Physicotechnical and Radiotechnical Measurements, Irkutsk, Russia

IVTAN Electromagnetic Field Expedition (Bishkek, Kyrgyzstan) of the Institute of High Temperatures, RAS

ESA European Space Agency, Germany

ESOC European Space Operations Center, Germany

FGI Finnish Geodetic Institute, Finland

Contributing Organizations

IDA International Deployment of Accelerometers / IRIS, Scripps Institution of Oceanography, USA

ASI Italian Space Agency, Matera, ItalyJPL Jet Propulsion Laboratory, California Institute of Technology,

Pasadena, CA, USAKAO Korean Astronomy Observatory, Taejon, KoreaKMS Kort & Matrikelstyrelsen, National Survey and Cadastre,

DenmarkLINZ Land Information New Zealand, WellingtonMAO Main Astronomical Observatory of the Ukrainian National

Academy, UkraineMO Manila Observatory, PhilippinesMIT Massachusetts Institute of Technology, Cambridge, MA, USANASA National Aeronautics and Space Administration, USANBSM National Bureau of Surveying and Mapping, ChinaNCAR National Center for Atmospheric ResearchNGRI National Geophysical Research Institute, Hyderabad, IndiaNIMA National Imagery and Mapping Agency, USAINGM National Institute in Geosciences, Mining and Chemistry

(INGEOMINAS), ColombiaNOAA National Oceanic and Atmospheric Administration, USANSF National Science Foundation NRCan Natural Resources of

Canada, Ottawa, CanadaROB Observatoire Royal de Belgium, Brussels, BelgiumOUAT Olsztyn University of Agriculture and Technology, PolandOSO Onsala Space Observatory, SwedenGSC Pacific Geoscience Center, Geological Survey of Canada,

NRCan, CanadaIERS Paris Observatory, International Earth Rotation Service, Paris,

FrancePOL Proudman Oceanographic Laboratory, UKROA Real Instituto y Observatorio de la Armada, Spain

RIG Research Institute of Geodesy, Geodetic Observatory Pecny, Ondrejov, Czech Republic

RGO Royal Greenwich Observatory, UKRJGC Royal Jordanian Geographic CenterRAS Russian Academy of SciencesRDAAC Russian Data Archive and Analysis

Center, Moscow, RussiaSOEST School of Ocean and Earth Science and Technology,

University of Hawaii,USA SIO Scripps Institution of Oceanography, San Diego, CA, USASAO Shanghai Astronomical Observatory, ChinaSCIGN Southern California Integrated GPS Network, USASRC-PAS Space Research Center of the Astrogeodynamical

Observatory, PolandSK Statens Kartverk, Norwegian Mapping Authority, NorwaySOI Survey of IsraelL+T Swiss Federal Office of Topography, SwitzerlandTUM Technical University MunichUSNO U.S. Naval Observatory, USAUCAR University Consortium for Atmospheric ResearchUFPR University Federal de Parana, BrazilUNAVCO University Navstar Consortium, Boulder, CO, USAUB University of Bonn, GermanyCU University of Colorado at Boulder, Boulder, CO, USAUNR University of Nevada, Reno, NV, USANCL University of Newcastle on Tyne, United KingdomUPAD University of Padova, ItalyWING Western Pacific Integrated Network of GPS, JapanWTU Wuhan Technical University, China

Operations of the IGS

– Operational Data Centers • Retrieve data from receivers • Validate data and monitor station status • Translate raw GPS data into RINEX (Receiver Independent

Exchange) • Forwards appropriate files to Global Data Centers or Regional

Data Centers

– Global Data Centers organize the files on the basis of site and time, and provide Internet data access to users and analysts

– IGS Analysis Centers pick up the data from the Global Data Centers, and estimate precise orbits, Earth Rotation parameters (ERP), clocks, etc

– Analysis Center results are collected by the Analysis Coordinator and combined into the official IGS products

IGS Evolution

‘92 ‘93 ‘94 ‘95 ‘96 ‘97 ‘98 ‘99

Stations 28 42 95 112 139 194 201 221

DataAccess

3+ day 3 day ….. 1 day ….. 6hr <6hr Hourly &1-4 hr

Orbitrms, cm

50 40-25 25-16 ~10 …. 5 - 10 …. 3-10

Orbitaccess

2-3 wk …. …. 2 wk …. 2 wk,1d

…. -> Sub-daily,‘ultra’

CBISAccess

3000files

5000files

25,000files

30,000files

2109hosts

2244hosts

‘

Pilot Project IAG Approved Service --->

Products Predicted Rapid Final Units Biases

Orbit 100.0 10.0 5.0 cm 10.0

Clock 150.0 0.5 0.3 ns ?

Pole 0.2 0.1 mas 0.3

LOD 60.0 30.0 s/ d 20.0

Stations Horizontal 3.5 mm 10.0

Stations Vertical 8.0 mm 20.0

Troposphere ZPD 4.0 mm 6.0

Geocenter X,Y 7.0 mm 20.0

Geocenter Z 13.0 mm 50.0

Terrestrial Scale 0.4 ppb 15.0

Estimated Quality of IGS Products

June 1999

Network Densification

• In 1993 the IGS realized that simultaneous processing of many stations was impractical

• IGS groups began investigating the rigorous combination of solutions rather than raw data analysis– 1994 Workshop on Densification of the International Terrestrial

Reference Frame initiated– SINEX - Solution Independent Exchange Format accepted in 1996– Combination of global station solutions since late ‘96– Polyhedron Solutions improving (see Annual Report Series)– IGS contribution to ITRF significant

• Establish IGS Reference Frame Coordinator June ‘99 at Natural Resources of Canada, Remi Ferland

Densification Project

Densified IGS network of ~200 - 250 globally well distributed sites -- goal that any user is within 1500 - 2000 km of a precise reference station – Regional analyses produced by Associate Analysis Centers called

RNAACs (Regional Network Analysis Center) who• produce solutions for regional network using IGS products

Solutions written into an ascii format call SINEX, Solution Independent Exchange format

– Regional solution is made available to Global Network Analysis Centers (GNAACs) who

• combine and compare solutions from all regional analysis centers

• Result is a dense homogeneous network of stations in unique, consistent reference frame (ITRF)

IGS/BIPM Precise Time Transfer

• Chaired by J. Ray, USNO (USA) & F. Arias, BIPM (France) Study accurate time and frequency comparisons– Develop operational strategies to exploit GPS measurements for

improved accurate time and frequency comparisons world

• Significant to maintaining UTC as new generation of frequency standards emerge– New/upgrade receivers at time labs– Data analysis– Key issue is calibration of instrumental delays to relate GPS clock

estimates to external standards– Time transfer comparisons, simultaneously with independent

techniques

Ionosphere Working Group

• Chaired by J. Feltens, ESA-ESOC, Germany• Working group, active through increasing solar

maximum– Calibration of Radio Signals (GPS and others)– Ionosphere Maps

• Develop combined IGS global ION maps• Validation of maps, may lead to improved IGS ionosphere

model

– Assessing stochastic behavior of the Ionosphere – Supported high rate GPS data acquisition and analysis during

August 11, 1999 solar eclipse

• IONEX is the ascii file exchange format; these files can be accessed at the Global Data Centers

LEO (Low Earth Orbiters)

• Working Group chaired by M. Watkins, JPL, USA – Determine role of IGS in future GPS LEO missions, POD +?– Oersted,Sunsat, SAC-C, CHAMP, GRACE, GLAS, …– Support of LEO occultation experiments for atmospheric profiling

• IGS Network component, obvious infrastructure to support robust, high-rate, low latency data requirements– Other applications require timely availability of data (seconds to

hourly)

• Discussing LEO data as element of IGS– Analyze effects of inclusion in analysis, improve IGS Products?– Evaluate potential contribution of AC’s to LEO effort

• Use early missions as case studies and analysis proof of concept

Troposphere Project• Chaired by G. Gendt, GFZ, Germany • Continuous well distributed measurements of water

vapor are of great interest for numerical weather prediction, climate research and atmospheric studies– Collocation of precise meteorological instruments to convert Zenith

Path Delay (ZPD) to Percipitable Water Vapor (PWV), need dry delay from barometric pressure, more meteorological instruments needed

– Zenith Path Delay (ZPD) estimated by all IGS AC– ~100 sites, combined ZPD at 2 hour interval– Consistency of Combination among Acs at 4mm level – Comparison to Water Vapor Radiometer (WVR) at Potsdam agree

to 1mm of Precipitable Water Vapor (PWV)

• Official product available at GDC’s & CBIS

GLONASS Pilot Service

• International GLONASS experiment IGEX, Investigated uses of GLONASS for geodetic and geophysical applications– October’98 - April’99, 61 GLONASS sites, 30 SLR stations – Interoperability of GPS/GLONASS– Precise Orbit determination and reference frame: PZ90 - ITRF96/97– Time offsets between GPS and GLONASS systems and GLONASS

systems to UTC– Orbits average throughout ~ 20- 30 cm between ACs– 1m level comparisons GPS-SLR solutions

• Demonstrates the extensibility of IGS to accommodate other microwave systems, e.g. GALILEO, GNSS

• Pilot Service charter approved by IGSCB, effort led by J. Slater, NIMA USA

Sea Level Monitoring

• GPS for monitoring tide gauge benchmarks (TGBM) and altimeter calibration– Decouple crustal deformation effects at tide gauge

benchmarks from ‘true’ long term sea level trends

• IGS/PSMSL (Permanent Service for Mean Sea Level) -- Cross discipline, joint activity

• Currently an seed initiative, not yet a full working group in IGS

• Recommendations stemming from 1997 workshop, see IGS publications

• Technical specifications development led by M. Bevis, University of Hawaii, USA, member IGS GB, Chair of IAG Subcommission VIII– Recent list prepared of GPS at TGBM (IGSMail #2501)

IGS Web Site

The Central Bureau Information System is a key resource for all users

• One of the first websites in 1993, originally developed with W. Gurtner , AIUB

• IGSMail, IGS Reports• IGS Directory, Calendar• On-line Publications• Links to IGS sites and other locations of interest• Rich FTP archives• Tracking station information, site logs, network

information• FAQ

Summary

• The economics of GPS make the measurement technology available to all IGS users

• The organization and outreach of the IGS enables users to take advantage of data, systems, and products developed cooperatively with the top international GPS experts

• Through the IGS standards are developed and adopted worldwide, contributing to robust, homogenous reference frame and implementing common processes

• IGS is a supporting foundation for nearly all GPS projects and numerous applications

Conclusion

• Tutorial development is our approach to promote extended and appropriate use of IGS products – Plan to continue developing tutorial– Many thanks to those involved in preparing the tutorial – Special thanks to Jan Kouba for coordinating this effort

• It is the dedicated contribution of many people and organizations that make the IGS so successful!