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Projet Projet AFREFAFREFECA Geo-information ECA Geo-information Systems SectionSystems Section Dozie EzigbalikeECA Geo-information Systems Section
In Brief
A scientific project using modern satellite based positioning to: Define a uniform geodetic reference frame Africa,
which will form the basis of national three-dimensional reference frames consistent with the International Terrestrial Reference Frame (ITRF)
Establish a network of GNSS base stations for mapping and position determination all over Africa
Support scientific research in satellite
Continental Coverage
Network of permanent GPS/GNSS base stations covering the whole continent
At least one in every country
Eventually, everywhere in Africa less than 1000 km from a base station
African Ellipsoid
Data from the base stations will be used to compute the parameters defining the best-fitting mapping surface for the African continent
Geodetic Reference Uniform geodetic
reference frame for Africa Basis for national three-
dimensional reference networks
Consistent with the International Terrestrial Reference Frame (ITRF)
Precise positioning requires real-time differential observations with two receivers AFREF will provide
network of base stations for practitioners
Major Uses and Applications
Regional Integration Watersheds, river
basins, ecosystems, wildlife are cross-border features
Regional infrastructure: roads, rail lines, water ways, …
Projects usually start at opposite ends
All require uniform mapping surface for regional analysis and planning
Peace and Security AU Border programme to delimit and demarcate
all borders by 2012 requires neighbouring countries to agree on common borders
This requires the borders to be mapped on the same coordinate systems That is, the same mapping surface The same reference frame
Presently, every country has its own reference frame and associated coordinate systems Country borders drawn on these national coordinate
systems are not always consistent Uniform coordinate system of AFREF will result in
consistent representation of borders by neighbours Reducing disagreements and conflicts
Global Conformity
AU vision for Africa … “which asserts itself as a vibrant and dynamic force in the global arena”
Not yet in geodesy AFREF will result in better fit of Africa to rest of
the world
International Mapping Standard
Current positioning technology based on satellite systems (GNSS) Positions are defined in the World Geodetic System
(WGS) International Civil Aviation Organization
(ICAO) adopted World Geodetic System (WGS84) for consistent mapping of Reference Points (ARP)
African countries are complying using satellite positioning technology
Need to have other geoinformation products (topography, cadastre, etc) in similar satellite-based coordinate systems
Other Uses
Disaster mitigation Search and rescue
Vehicle tracking and fleet management Agriculture Monitoring
Crop Area mapping … …
Climate & Weather Estimation of precipitable water vapour from network of
GNSS stations in South Africa
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March 2004 (dd hr min) UT
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Atmospheric Research
Atmospheric research Space weather
o Ionospheric mapping of variation of annual TEC over South Africa from network of GNSS base stations
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20022004
Thanks to B Opperman of Hermanus Magnetic Observatory for plots
Atmospheric Research 2
Plate motions Plate motion estimates in South Africa from network of
GNSS base stations
C.J.H. Hartnady, E. Calais & R. Wonnacott (2007): “ITRF2000 velocity field from the South African TrigNet GPS array and the African GNSS network: Implications for Nubia-(Rovuma-Lwandle-)Somalia plate motions” East African Rift Conference, Kampala
Geophysics Research
Objectives and Expected Outputs
Formal Objectives 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 three-dimensional 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.
Formal Objectives 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.
Institutional Acceptance 1 Un Economic Commission for Africa
CODI (now CODIST) an inter-governmental body of ECA Have adopted the importance of AFREF and the Windhoek
Declaration Created a Working Group to deal specifically with AFREF AFREF field project in work programme of ECA
UN Office for Outer Space Affairs (UNOOSA) Have recognized importance of AFREF for variety of applications Supported the Cape Town workshop and funded travel of
participants to several AFREF-related events International Association of Geodesy (IAG )
Have recognized importance of AFREF and have committed support
Have created structures to co-ordinate project and provide technical assistance expertise
Supported the Cape Town workshop
AFREF Structure (1)
To be designed, managed and executed from within African
Regional organization into: NAFREF, WAFREF, CAFREF, EAFRAF, SAFREF
To be executed at the national level by national organizations responsible for geodetic matters
Technical expertise and support from the international geodetic community such as IAG, IGS etc.
AFREF Structure (2)
BureauSteering
Committee
AMCOST
AFREF Joint Secretariat
AU/HRST ECA/ISTD
Technical AdvisoryWorking Group
Scientific AdvisoryWorking Group
Sudan
Algeria
Egypt
Mauritania
Moro
cco
Libyan Arab Jamahirya
Tun
isia
Western Sahara
Mali Niger
Nigeria
Gh
ana
Guinea
Côte D'Ivoire
Senegal
Burkina Faso
Ben
in
Liberia
Tog
oSierra Leone
Guinea-Bissau
Gambia
Cape Verde
Chad
Congo
Cameroon
Gabon
Central African Republic
Equatorial Guinea
Sao Tome & Principe
Ethiopia
Tanzania
Dem. Rep. of the Congo
Kenya
Somalia
Madagascar
Uganda
Eritrea
Burundi
Rwanda
Comoros
SeychellesSouth Africa
Namibia
Zambia
Mozambique
Botswana
Zimbabwe
Ma
law
i
Lesotho
SwazilandNAFREFWAFREF CAFREF EAFREF SAFREF
Sub RegData Processing SRDPSRDP SRDP SRDP
Planned Activities 2008-09
May – June 08: Develop draft open data access policy and draft participation charter
June 08: Meeting of Current AFREF Steering Committee during Africa Array meeting in Johannesburg
June – Nov 08: Installation of five reference stations donated by Trimble
July 08: collect data on ongoing GPS/GNSS projects and initiatives in Africa
Aug 08: Training session at RCMRD Mar 09: CODIST Meeting
• The strategy leads with building a Partnership with The strategy leads with building a Partnership with Providers.Providers.
• Contacts with Trimble
• Donation of the five GPS reference stations equipment that will add
to the network of stations, for the determination of the African
reference frame as well as being part of network of continuously
observing reference stations (CORS).
• In addition, the Commission has developed a proposal to densify the
network such that positioning professionals (surveyors, engineers,
environmentalists, mineral prospectors, etc) would always have
access to parameters of at least one reference point within 500Km
from any place in Africa
AFREF : Operationalization 1
• The strategy leads with organizing an African The strategy leads with organizing an African Policy Makers’ Workshops.Policy Makers’ Workshops.• To channel the Project into the NEPAD’s Programme on Science
and Technology
• To set up the activities into the umbrella of the ministerial
structures of the African Union, notably the African Ministerial
Council on Science and Technology (AMCOST).
AFREF : Operationalization 2
Designation CostTotal Cost
Y1 Y2 Y3
1. Equipments 110 000 1 166 000 1 078 000 2 354 000
2.Capacity Building 105 000 287 000 271 000 663 000
3. Services 168 000 168 000 168 000 504 000
4. Management 200 000 200 000 200 000 600 000
5. Others costs 278 577 278 577 278 577 835 730
Grand Total 861 577 2 099 577 1 995 577 4 956 730
AFREF : Funding