Status Summary

1
Realizing a Continental Reference System for
Africa
AFREF Considering the Roles of the International
Association of Geodesy, International GPS
Service, and UN-Office of Outer Space
Affairs
Pre-conference Workshop on AFREF African
Association of Remote Sensing of the
Environment Nairobi, Kenya October 17, 2004
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Outline of Presentation

• AFREF Rationale
• Roles of International Organizations
• Way Forward with Support
• Summary

GPS Station with solar power, wireless
communications
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Overview

• AFREF - African Reference System
• Establish a continental reference system -- with
  sustainable technology
• Provides the geodetic infrastructure for
  development throughout Africa
• Key to modernizing national reference systems
  through satellite and space geodesy GPS, VLBI,
  SLR, DORIS, GLONASS, future GNSS (Galileo)
• Three dimensions, horizontal and vertical, and
  velocities
• Includes gravity measurements as an essential
  component
• IGS/ITRF methodology at global and regional
  scales EUREF (European), SIRGAS (South America)
  examples of approach and realization

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AFREF - Rationale

• Communication and internet are critical to
  success and sustainability of GNSS infrastructure
• access to information, global data, products, and
  technology advances
• Increase knowledge base, capacity building
• Training, education, access to resources,
  retention of quality personnel and stability are
  issues
• Collective approach within African nations
• Each adopting similar methodologies and
  technology
• Permits progress where practical, implementing a
  network of GPS stations
• Support and training envisioned by IGS/ITRF -
  seeking resources

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AFREF - Rationale

• Need for a geodetic structure gaining recognition
  throughout Africa and international partners
• The 50 nations within Africa can realize a
  homogeneous reference system consistent with ITRF
  
• UN GNSS Workshop Zambia July 2002 - AFREF
  recommendations
• Approach plan regional, implement national -
  Windhoek Declaration Dec 02, SAREF model for
  regional implementation
• Support of international organizations
• United Nations Office of Outer Space Affairs
  (UN-OOSA)
• International Association of Geodesy
• International GPS Service
• International Terrestrial Reference Frame

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UN-OOSA GNSS Action Team

• Charter for the Action Team on Global Navigations
  Satellite Systems
• Using space applications for human security,
  development and welfare, action should be taken
  to improve the efficiency and security of
  transport, search and rescue, geodesy, and other
  activities by promoting the enhancement of
  universal access to and compatibility of
  space-based navigation and positioning systems.
• In parallel, 4 Regional Workshops on GNSS
  organized under UN auspices
• July 2002 - Lusaka, Zambia
• AFREF concepts addressed, great venue for
  discussion and planning
• Other workshops in Malaysia,Chile, and Austria
• Report and recommendations finalized December
  2003
• Report available from UN-OOSA
• http//www.oosa.unvienna.org/SAP/gnss/index.html
• Recommendation to establish an International
  Committee on GNSS
• Mechanism for coordination, see report
• Key recommendation on AFREF (next)

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UN-OOSA GNSS Action Team
Extract from Report Surveying, Mapping and Earth
Science, Recommendation 1 Establish a
continental reference for Africa, or African
Reference Frame (AFREF), consistent with the
International Terrestrial Reference Frame A
uniform coordinate reference system is
fundamental to any project, application, service
or product that requires some form of
geo-referencing. Many developing countries, and
particularly the African countries, would benefit
greatly from a modern GNSS-based reference system
that can be used for national surveying, mapping,
photogrammetry, remote sensing, Spatial Data
Infrastructure (SDI), Geographical Information
Systems (GIS), development programs, and hazard
mitigation (earthquake studies, fault motion,
volcano monitoring, severe storms). Many existing
national coordinate systems are based on
reference figures of the Earth which are
generally outdated and are restricted to a
particular country, making cross-border or
regional mapping, development, and project
planning very difficult. A continental reference
system for Africa should be organized through an
international project, known as AFREF, with
common goals and objectives throughout Africa,
and with the commitment of African countries and
the support of international partners. The
benefits of GNSS technology cut across
applications and across countries. It is further
emphasized that the importance of simultaneous
development of information and communications
technology (ICT) and related infrastructure is
necessary for sustainable use of GNSS. Policy and
decision-makers should be made aware of the
critical importance of ICT to the successful
utilization of GNSS.
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International Association of Geodesy

• IAG re-organization adopted in 2003,implements a
  new structure that
• Will have a focus
• Is based on the three pillars of modern geodesy,
  namely
• geometric shape of the Earth
• Earth's gravity field, and
• orientation of the Earth in space
• Will better incorporate the very successful IAG
  services, among others, by representation in the
  IAG Executive Committee
• AFREF initiative has strong support of the IAG
  Exec. Committee
• IAG new structure is a mechanism to engage and
  support AFREF
• Commission 1, Reference Frames (Prof. Herman
  Drewes)
• Sub-commission 1.3, Regional Reference Frames
  (Zuheir Altamimi)
• Sub-commission 1.3d Africa (Richard Wonnacott)
• IAG new project the Global Geodetic Observing
  System (GGOS)
• Focuses on importance of long term geodetic
  measurements as integral component of Earth
  system science
• http//www.iag-aig.org/

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International GPS Service

• IGS was established in 1994, and celebrates 10th
  Anniversary this year
• IGS Mission is
• committed to providing the highest quality
  data and products as the standard for global
  navigation satellite systems (GNSS) in support of
  Earth science research, multidisciplinary
  applications, and education. as well as to
  facilitate other applications benefiting
  society.
• 200 organizations, 80 countries, and a 350
  ground tracking network of both GPS and Galileo
  receivers
• Most precise GPS/GLONASS data and products
  available anywhere, orbits, clocks, station
  positions
• IGS contributions to ITRF enable densification,
  while further allowing users ready access to the
  ITRF
• See IGS Website http//igscb.jpl.nasa.gov/index
  .html

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IGS Supports AFREF

• The economics of GPS make the measurement
  technology readily available and globally
  accessible to all 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/GNSS experts
• Standards are developed and adopted worldwide
  through the IGS activities
• contributing to robust, homogenous reference
  system
• implementing common processes
• IGS is a supporting global foundation for nearly
  all regional and national GPS and GLONASS
  geodetic networks, projects, and numerous
  applications worldwide
• Must ensure appropriate evolution, coordination,
  and interoperation of mutliple GNSS systems for
  societal and scientific benefit
• IGS has long term commitment to AFREF
• AFREF is for Africa, must be an African led
  project
• Success is a long term effort
• Count on strong partnership with IGS

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IGS Tracking Network 2004
http//igscb.jpl.nasa.gov/network/netindex.html
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International Terrestrial Reference Frame

• ITRF is one of the key activities of the
  International Earth Rotation and Reference System
  (IERS) an IAG Service (older than the IGS)
• ITRF is defined by combination of technique
  observations, analysis and products VLBI, SLR,
  GPS, DORIS and the conventional survey ties that
  relate these measurement systems
• AFRICA has one of the worlds fundamental stations
• Hartebeesthoek, all techniques collocated
• African densification best realized with GPS/GNSS
• New website available this month, please visit
• http//www.ensg.ign.fr/ITRF/
• ITRF expresses strong support for AFREF
• Notes the need to integrate existing permanent
  GPS stations into the IGS Network, the backbone
  of AFREF

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Space Geodesy in Africa
VLBI
SLR
GPS
DORIS
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Motion of African Plate
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Way Forward

• Whats Next for the AFREF vision?
• Suggestions include
• Project formalization within Africa very timely -
  Lets get it started!
• CODI? ECA? AOCRS? Other?
• Consider formation of steering committee or
  oversight group dedicated to detailed project
  planning
• Validate regional approach, methods, compelling
  arguments for policy makers
• Outline project phases, goals and objectives
• Include all technical components - gravity is
  critical to AFREF
• Consider a call for participation (CfP) (Based on
  IGS experience)
• Develop a document that calls for participants to
  contribute or play various roles - many groups
  will need to bring their own resources, other
  groups may use such a CfP to seek and secure
  resources
• Distribute CfP widely, require letter responses
  to the committee outlining contributor resources
  and commitment for specific periods of time (4 to
  5 years?)
• Include distribution to international
  organizations and agencies for participation and
  partnership
• Establish follow-up meetings and distribute
  meeting minutes broadly
• Use the AFREF mailing list or move the service
  from IGS to Africa, it is a great way to keep
  people informed (http//igscb.jpl.nasa.gov/mail/m
  ailindex.html)

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Summary

• AFREF has great promise and tremendous potential
• Excellent time to move forward
• Cooperation is implicit within Africa and
  internationally
• Regional structures with an agreed to continental
  agenda will ensure progress
• International organizations described in this
  presentation are strong partners and will work to
  assist wherever possible
• Good luck with further discussions today and this
  week!

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Acknowledgements Notes

• Collective vision and dedication prove to be
  successful and beneficial for all!
• The IGS Central Bureau is funded by the National
  Aeronautics and Space Administration and offices
  are located at the Jet Propulsion Laboratory in
  Pasadena California. It is important to
  recognize the significant contributions of all
  organizations worldwide who support and sponsor
  IGS activities.
• This presentation was compiled and prepared by
  Ruth Neilan, who very,very much regrets not being
  able to attend this important workshop.
  Acknowledgements are due to UN-OOSA, IAG, and
  IERS/ITRF and Zuheir Altamimi for the ITRF
  charts. Also to Richard Wonnacott for carrying
  this presentation to the meeting.
• Kindest regards to each of you and much success
  for AARSE.

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Back-up Slides
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Basic Need for Geodetic Networks

• Uniform coordinate reference system is
  fundamental to any development project,
  application, or service requiring some form of
  geo-referencing
• All countries have established some form of
  geodetic reference systems for
• National surveying, Mapping, Photogrammetry,
  Remote Sensing, Geographical Information Systems
  (GIS),Spatial Data Infrastructure (SDI)
• Development programs
• Hazard mitigation earthquake studies response,
  fault motion, volcano monitoring, severe storms,
  sea-level rise, etc.
• Traditional national reference frames are
  inadequate for regional, continental, or global
  initiatives
• Long term, systematic measurements of the Earth
  system require the availability of the
  International Terrestrial Reference Frame (ITRF)
  that is stable over decades
• GNSS networks provide a major element of the
  critical infrastructure necessary to develop,
  densify, and maintain the ITRF

ITRF is a set of positions and a model for how
those positions evolve with time
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WHY IGS?

• Key factors in formation of IGS
• All geodynamics, geodetic, and space agency
  organizations realized the potential of GPS by
  late 1980s
• Motivating goal millimeter positioning in
  support of science engineering anywhere in the
  world
• Not one agency can or should assume the capital
  investment recurring operations costs for the
  entire infrastructure
• Join with key international partners to form
  federation, define cooperation, set standards,
  driven by science quality
• Implement a global civilian GPS tracking system
  for science and research
• Global framework for virtually all regional
  national network applications

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IGS Projects Working Groups

• Reference Frame Coordination and Working Group
• Generate a robust and homogeneous reference
  system, relating scientific results anywhere in
  the world -gt major component of the ITRF
• Plot network time series, position and velocities
  support plate motion and crustal deformation
  studies
• IGS Clock Products - Time and Frequency
• Exploit GPS measurements for improved accurate
  time and frequency comparisons worldwide, sub
  nanosecond
• Joint with the BIPM in France
• Low Earth Orbiter (LEO) Project
• Generate precise orbits for LEO satellites
  CHAMP, SAC-C, GRACE, JASON,
• Support occultation measurements for atmospheric
  profiling- this technique will revolutionize
  weather forecasting within the next decade
• GLONASS Service Pilot Project IGLOS-PP
• Flexible GNSS model - classic products from
  Russian GLONASS system
• Tropospheric Working Group
• Derive total zenith path delay or precipitable
  water vapor for GPS observations
• Ground-based meteorology, weather forecasting
  (severe storms), climate

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IGS Projects (cont.)

• Ionospheric Working Group
• Use dual frequency GPS data to determine Total
  Electron Content (TEC) including its temporal and
  spatial variations, map the Ionosphere
• Sea Level Project - TIGA
• Measuring long-term motion at tide-gauges to
  assess sea level change
• decouple crustal deformation or subsidence
  signatures at coastal areas from long-term
  sea-level changes, ocean loading effects
• Support satellite altimeter calibration at
  specific sites and inter-mission calibrations,
  TOPEX, JASON, etc.
• Real-time Working Group
• Develop international standards for cooperation
  of real-time data exchanges
• Eventual generation of real-time products
• Data Center Working Group
• Developing schemes to support increasing demand
  for data and products
• GNSS Working Group
• Develop technical concepts and incorporate
  Galileo, modernized GPS and any future GNSS into
  IGS processes, GLONASS as example

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Nubia-Eurasia rotation pole location
Nubia-Eurasia velocity 50 slower than NUVEL1-A
prediction