United Nations Economic Commission for Africa CODIST II - Geo R Wonnacott Addis Ababa 2 May 2011

1. Call for Participation for The Processing of AFREF GNSS Data United Nations Economic Commission for Africa CODIST II - Geo R Wonnacott Addis Ababa 2 May 2011

2. Overview • Executive Summary • Summary of Call for Participation • Details of Areas of Participation • Background to AFREF • References

3. Background • Fundamental point of departure for projects, services or products requiring geo-spatial information is a uniform & reliable co-ordinate reference frame. • Over 50 countries in Africa each with their own geodetic reference system and frame and some with 2 or more systems. • Although there are many areas of conflict there are also areas where peace has been restored and require a lot of development. • It is known that many private commercial enterprises are setting up their own reference frames particularly in the oil and mining industries. • AFREF is, therefore, an African initiative to unify the geodetic reference frames of Africa based on the ITRF through a network of GNSS base stations at a spacing such users will be at most within ~1000 km of a base station.

4. International Endorsement • UN ECA CODIST (Committee on Development Information, Science & Technology) • Have adopted the Windhoek Declaration • Created a Working Group to deal specifically with AFREF • UN OOSA (UN Office for Outer Space Affairs) • Have recognized the importance of AFREF for variety of applications • Supported travel for some AFREF activities • IAG (International Association of Geodesy) • Have created structures to co-ordinate the project and provide technical assistance and expertise • IGS (International GNSS Service) • Has strong commitment to support AFREF

5. Objectives of AFREF 1 • To determine a continental reference system for Africa consistent and homogeneous with the global reference frame of the ITRF as a basis for national 3-d reference networks. • To realize a unified vertical datum and to support efforts to establish a precise African geoid. • To establish continuous, permanent GNSS base stations at a spacing such that the users will be within 1000km of a base station and that data is freely available to all nations.

6. Objectives of AFREF 2 • To determine the relationship between the existing national reference frames and the ITRF to preserve legacy information based on existing frames. • To provide a sustainable development environment for technology transfer so that these activities will enhance the national networks and other applications. • Assist in establishing in-country expertise for implementation , operation, processing and analysis of modern geodetic techniques, primarily GNSS.

7. Progress to Date 1 • The AFREF Operational Data Centre (ODC) is currently archiving on a daily or near daily basis data from nearly 62 permanent GNSS base stations at average of 31 stations daily ( as at mid-April 2011). • Data is freely and openly available to all users. • Project reached the stage where a computation of all available stations can be carried out. • National Mapping Organizations will be able to use results plus available GNSS data from ODC to compute National Reference Frames based on ITRF.

8. Progress to Date 2 • Active stations being archived at the AFREF Operational Data Center • (February 2011)

9. Progress to Date 3 • Number of activities underway to install permanent base stations or move towards ITRF: • Algeria Angola • Benin Botswana • Cameroon Egypt • Ethiopia Ghana • Kenya Lesotho • Malawi Moroco • Mozambique Namibia • Nigeria Rwanda • South Africa Swaziland • Tanzania Tunisia • Uganda Zambia

10. Progress to Date 4 • As agreed at CODIST I (April 2009), an Operational Data Centre has been established. • www.afrefdata.org or ftp.afrefdata.org • Data from 62 (mid-April 2011) continuous stations brought together from number of data centres into one place. Data centres include: • CDDIS • HartRAO • NGS • TrigNet • UNAVCO • Nignet • SEGAL • Plus data from 3 stations being directly downloaded from receivers

11. Progress to Date 5 • Number of stations listed for which no data available - it is known that these stations are operating but data not available. • Number of campaign stations listed hence only periodic data available .

12. Areas of Participation 1 • Processing and analysis of data from the network of GNSS base stations to produce a continental reference frame: • Computation of network of fiducial stations based on well established stations with long term reliability and publically available data; • An initial processing will provide set of co-ordinates for use at National level - frozen in time; • In addition will provide ongoing processing to maintain network and provide set of velocity vectors and to make allowance for the addition of new stations; • Processing to be done using IAG guidelines.

13. Areas of Participation 2 • Computation of national networks based on the continental reference frame: • Major objective project is conversion of National geodetic networks to AFREF and hence ITRF; • NMOs will have to occupy number of strategically placed points whose co-ordinates are well established in the National frame using GNSS; • Processing could either be as series as campaign or using permanent stations to convert / transform current frame to AFREF; • Respondents will have to set out proposed strategy.

14. Areas of Participation 3 • Training and capacity building of geodesists and surveyors in NMOs and Universities • Respondents to CfP will be required to address the following: • Describe the form of training whether for individuals or components of NMOs; • In case of individual training, will training lead to some form of qualification?; • What level of sponsorship will be offered, if any? ; • Proposal must describe level of expertise required to undertake training; and • Any other details not covered in the above.

15. General • Call for Participation includes a section on the background to AFREF which will not be covered in this presentation. • Commitment to project to be at least 5 yearsto create an environment for sustainable environment. • Proposals to be evaluated by panel of independent experts. • The CfP also covers multi-disciplinary aspects of AFREF such as collaborations with; • Africa Array - seismology • Africa Monsoon Multi-disciplinary Array-GPS (AMMA-GPS) – meteorology • Scintillation Network Decision Aid (SCINDA) – space weather • Dates for submission of CfP proposals still to be finalized.

16. Inter-disciplinary Collaboration

17. Thank you

18. Global Context 1 Global distribution of four space based positioning techniques available for realization of International Terrestrial Reference Frame (ITRF) + GPS Only ;+DORIS only;+ SLR Only;+VLBI Only 4 Techniques; 3 Techniques; 2 Techniques

19. Global Context 1