Message-Id: Date: Wed, 02 Jan 2002 09:02:21 +0200 From: "Richard Wonnacott" To: Subject: [AFREF-13] AFREF (South) 13 March 2001 Meeting Minutes Sender: owner-afref Precedence: bulk ****************************************************************************** AFREF Mail 01 Jan 23:04:46 PST 2002 Message Number 13 ****************************************************************************** Author: Richard Wonnacott Establishing a Continental Reference System for Africa 'AFREF' Meeting Minutes Held In the Studio Baxter Theatre, Main Road, Rondebosch, South Africa 13 March 2001 1. WELCOME The Chairperson, Wonnacott opened the session to assess and discuss the interest in establishing a continental reference system for Africa, titled 'AFREF' and welcomed everyone present. There were representatives from Namibia, Botswana, Zimbabwe, Zambia, Malawi, Mozambique, Swaziland, Ghana, South Africa, Germany, the United Kingdom and the United States attending the meeting. 2. BACKROUND Wonnacott (CDSM) proceeded to give a background history on the purpose of hosting a meeting of this nature. He indicated that it was to discuss an African reference frame and the need to bring the various national geodetic datums within Africa together and relate these to the international reference system. He felt there was a need to gauge the level of interest with respect to initiating such a project within Africa. Wonnacott reported that there were over 50 countries in Africa with different datums thus making this a challenging task. He informed the meeting of the former ADOS Project (Africa Doppler Survey) which was started in the early 1980's but was not fully implemented nor was it sustainable. CODI (Committee on Development Infrastructure), a United Nations sponsored group within the Economic Commission for Africa has recognized the need to create a sound and consistent geodetic reference infrastructure covering the whole of Africa. EUREF, the coordinated European regional reference system, was initiated in the late 80's and has been extremely successful. The SIRGAS Project, which started in about 1993 is the South American equivalent of the AFREF and has been most successful in bringing those reference frames together. A similar project was started a number of years ago in the Asia Pacific region, termed the APSG - Asian Pacific Space Geodynamics Program. The International Association of Geodesy (IAG) and/or its International GPS Service (IGS) have provided the international infrastructure for many of these projects. Wonnacott suggested that the project would need to be regionalized since it would be rather difficult to coordinate such a project within all the countries of Africa simultaneously. It was felt that each regional project could be divided into 2 stages - firstly to establish a network of permanent or semi-permanent GPS base stations and, secondly, a series of separate smaller GPS campaigns to densify the network in each country or sub-region. Wonnacott felt that a project like AFREF need involvement of Africans at all stages of the project so that there could be a transfer of GPS and geodetic technology and expertise. This is the sentiment of IAG and IGS who advocate their supporting role for a largely African led initiative. 3. EXPRESSION OF SUPPORT 3.1 International Association of Geodesy (IAG) Neilan (IAG/IGS) gave an overview of her organisation, IGS (International GPS Service), indicating that it was a service of the IAG. Claude Boucher (unfortunately unable to attend this meeting) is also responsible for IAG Commission X (Global and Regional Geodetic Networks) and has been involved in the extension of the International Terrestrial Reference Frame (ITRF). In addition, she commented on the role of the International Earth Rotation Service (IERS)/International Terrestrial Reference Frame (ITRF) and expressed interest in achieving a continental extension of a reference system within Africa. The IGS is a federation of over 100 organisations that provide support to geodetic, geophysical research and engineering surveying activities, through the provision of GPS data and related products. They produce the best GPS orbits that are currently available and subsequent station locations and velocities, which essentially define and help to improve and evolve the ITRF (International Terrestrial Reference Frame). 3.2 International GPS Service (IGS) Neilan felt that in utilizing a methodology of a solution combination to bring continental or regional networks into the global reference frame, the same could be achieved in Africa. Within the IGS, utilizing combination solutions - station positions are of the order of 3 - 5 mm in the horizontal and less than a cm in the vertical, all of which are within the ITRF. She indicated that the Hartebeesthoek station was a fundamental point not only for Africa but globally as well. She pointed out that there are very few IGS stations within Africa and there is a need to establish more within the continent. As an international scientific organisation, IGS would assist by supporting the project and attempting to seek international resources should there be a keen interest shown within the African organizations. IGS has established an AFREF e-mail distribution list on their website that can be subscribed to via the Internet. Neilan indicated that a directory of contacts within Africa was also in the process of being developed. Neilan indicated that IGS would be very interested in realising a project like this within Africa of mutual benefit to African nations and the global scientific and engineering communities. 4. SIMILAR INTERNATIONAL PROJECTS 4.1 African Doppler Survey (ADOS) Kumar (NIMA) gave an overview of ADOS, which started in the 60's and picked up in the early 80's with 46 - 47 countries being involved. In 1984 after 300 - 400 reference stations had been realised, the project came to a standstill and no further phase had been determined. Many of the stations used in the ADOS project have been destroyed or cannot be recovered. Kumar indicated that he did not want to see this happen again with the AFREF project. 4.2 South American Reference Frame (SIRGAS) Kumar (NIMA) reported that a well-established geodetic network has already been implemented in Western Europe and North America, with South America being the next project. At the request of South America, the IAG, the IAG sub-commission for South America and the U.S NIMA (National Imagery and Mapping Agency) became the umbrella organisation to organize the project. In 1993, 11 out of the 13 South American countries were represented at a meeting held in Paraguay. The project initially could not attract Guyana and Suriname but these are now part of the ongoing SIRGAS effort. SIRGAS was implemented in various phases - phase 1 realizing the scientific part in which approximately 60 stations were placed on the continent, with a minimum of 2 - 3 per country. The second phase was to increase the density from the 60 stations to around 1000 stations. They first set up the datum at a few decimeter horizontal level and then tried to integrate the old datums after which each country could create its own unified system. Once the densified national datum was established they could then continue integration into the continental realization. Kumar felt that the circumstances should not be repeated by providing hundreds of stations as in the ADOS project and then not furthering implementation and reference frame maintenance. In reply to a question whether traditional terrestrial observations were included within SIRGAS by occupying existing triangulation points, Kumar responded by saying that the SIRGAS reference frame was established using traditional triangulation stations as far as possible. 4.3 European Reference Frame (EUREF) Weber from the German Federal Agency for Cartography and Geodesy (Bundesampt fur Kartografie und Geodesie - BKG), reported on the reference system used in Europe. There was a strong need for high accuracy GPS orbits and positioning (in some cases at the mm level) for both geodetic and geophysical research and applications. From this EUREF was born and is now a sub-commission of IAG Commission X and is very reliant upon the IGS for the global infrastructure and precise GPS products. EUREF is responsible for the ETRS (European Terrestrial Reference System), including 3D geometrical as well as physical gravity field related data for vertical reference (e.g. UELN, EUVN). Since 1999 there has been increasing interest in interdisciplinary activities from survey authorities, universities and research institutions. He reported that there is a good coverage within Europe and indicated that their tracking network includes almost 100 permanent tracking stations (more than 30 countries within the European region) at present of which 50% also contribute to IGS network. A small number of receivers are located outside Europe (North Africa, Middle East) for monitoring purposes. The organizational structure is built up of a co-ordination group, central bureau, and special projects sections. Data flow was considered important for permanent sites where 95% of the data comes in daily within a few hours and 35% of stations providing hourly data uploads. Data analysis is carried out at different analysis centers - with 13 analysis centers, each doing their own analysis. When it comes to millimeter accuracy it is important to have stations distributed and extended throughout the regional area. The result is that EPN provides consistent and high quality products over long time with quality control. EUREF is willing and able to include other sub-networks provided that they follow guidelines and rigorous standards for site quality and documentation. EUREF is studying the implementation of special products for specific needs of user groups. EUREF is the backbone for national activities and further densification of the ITRF and for georeferencing in cartography, GIS and navigation. Weber indicated that there would be a special interest within EUREF to see a uniform reference system coming out of Africa as Europe and Africa are close neighbors within this hemisphere and which they would support by way of transfer of knowledge, facilities, training, possible resources, etc. An important point raised by a participant at this point was that the national mapping organisations will have to play a very active role in the logistics support and participation in the densification program as well as in the establishment and maintenance of the permanent stations, providing a long term commitment to such an endeavour. 4.4 Asia and the Pacific Regional geodetic project Neilan (IGS) briefly discussed 2 aspects within Asia. In 1997 geodetic techniques were used as a basis to create a coordinated initiative for mapping in the Asia/Pacific area. In addition to this UN project, there was a long term initiative called the Asian Pacific Space Geodynamics Project (APSG) which is an ongoing project (over past 4-5 years). At a meeting held in October 1999 in Japan, the IGS were designated as the GPS technique coordinators for the project and all the stations in the region were encouraged to join into the IGS processes. In Japan there are 1000 GPS receivers which are used to process data on a daily basis essentially for the monitoring of crustal motion and earthquake probabilities and impacts. In China, stations were set up by the Chinese Academy of Sciences (CAS) and then by the China Seismological Bureau (CSB), which is now responsible for ~25 continuous GPS stations. They hope to extend this to ~260 stations. However, some restrictions on data exchange or release of data are being addressed. The project is known as the Crustal Monitoring Observation Network of China (CMONOC). A question from Parker (CDSM) was raised as to the advantages of having a continental reference frame rather than global reference frame. Neilan responded by indicating that there are number of stations in Africa which can help define the reference frame which can be tied into the national datums and national reference systems so that you can have access to the current level of the precise reference system. This is important for many applications that have no borders, for example: Geographic Information System assets, satellite mapping control, environmental mapping and management, continental infrastructure development and enabling access to the technology utilized by nations worldwide within a common reference. Kumar commented that global and continental reference frames would become the reference for national datums. South Korea and Thailand are in process of utilizing this process. Weber (BKG) indicated that it was not 2 different reference frames, rather a densification of a global system. Leonard (Euro Geographics) felt that the fundamental survey principle of working from the whole to the part should not be forgotten. 5. AFREF 5.1 Benefits - Open Discussion Smith (Omnistar) who works in neighbouring countries felt that the problem which he was encountering, was the matching of the WGS84 with existing reference systems, and therefore would strongly support a unified system. Jeffereys (Air Survey Co. of South Africa) reported that they needed to find national points on which to set up their bases and try and fit the geoid to the ellipsoid for that area. He felt that the benefits would be a tremendous advantage as they would all be utilizing the same system. Merry (UCT) agreed - one of the problems currently being encountered is that there is sometimes a need to transform from WGS84 to the local datum, therefore a link or relationship would need to be determined. Tait (ESKOM) commented that ESKOM wants to build an electricity supply grid throughout Africa and a unified reference frame would be highly beneficial to achieve this. Wonnacott (CDSM) felt that a number of problems were also experienced when trying to define international boundaries (land and maritime). Combrinck (HartRAO) felt that from a scientific perspective, it would be beneficial by allowing them to open up avenues of geodetic and geophysical research in Africa. Chigumete (Zimbabwe) enquired as to the efforts that will be made to ensure that the project covered the entire continent. Neilan indicated that recognition has been given to the fact that there is a need to have a geodetic structure in place and was emphasized at a meeting which was held in Nice, April 2000, and included representatives from the United Nations Africover project. They were looking at defining a geodetic base for Africa. Kumar (NIMA) reported on the Africover project indicating that the main trouble was that there was no reliable and uniform geodetic structure in place - differences of up to 300 m were being experienced in the mapping control. He insisted that the basis should start at the scientific or broader level and then move to national level (which would form the backbone of mapping) and must include the geoid into the process. Leonard (Euro Geographics) felt that a start on the project needed to be made somewhere and that if it began in the southern Africa, other regions in Africa would be to likely join in. Jeffereys Air Survey Co. of South Africa informed the meeting that experiences in Lesotho demonstrated discrepancies, however there was no representative at the meeting to respond to his query. Weber (BKG) spoke of possibly having a new Global Navigation Satellite System (GNSS) being considered by the European Union and partners, to be known as Galileo. Habana (Botswana) asked how much investment would be required for this project. Wonnacott indicated that this is difficult to answer and would depend on being able to find organizations to either donate expertise or to support the project financially or with equipment and the level of work required in each country. This would be a key focus of the project planning phase. 5.2 Possible Role Players 5.2.1 African National Surveying and Mapping Agencies - Wonnacott (CDSM) indicated that these organisations must be involved from an early stage and in all stages. He requested tentative support from these agencies. Participants who indicated their support were from the following countries: Botswana, Ghana (as an observer in the Southern Africa project), Malawi, Mozambique, Namibia, South Africa, Zambia and Zimbabwe. 5.2.2 Committee on Development Infrastructure (CODI) - Neilan informed all of the CODI contact (Prof. Konecny) who unfortunately could not attend this meeting. Neilan informed all that within CODI there was a resolution that there should be a unified system within Africa - a meeting will be held in September 2001 in Adis Ababa, Ethiopia. CODI has a GIS focus that requires a strong geodetic infrastructure on which to base an extensive African GIS. 5.2.3 Africa Spatial Data Infrastructure (Africa SDI) - The Africa SDI is a subgroup within the GSDI (Global Spatial Data Infrastructure) This group held a meeting in Cape Town in March 2001 in conjunction with a GSDI meeting. Wonnacott mentioned that they wanted to create large spatial datasets for Africa but had not yet considered the reference frame to be used. 5.2.4 Hartebeesthoek Radio Astronomy Observatory (HartRAO) - Combrinck (Head of Geodetic component at HartRAO) gave overview on HartRAO and indicated that they run VLBI SLR and GPS programmes for both geophysics and geodetic applications and projects. HartRAO is a designated Regional Analysis Centre for IGS and operates a few IGS stations within the region. Combrinck sees HartRAO's contribution at a scientific level - encouraging fixed reference stations in each country as well as the need to provide ongoing training sessions. He indicated an interest in establishing contacts with people, to set up systems and bring students from those countries to South Africa and possibly provide training at HartRAO or the University of Cape Town (UCT). He reported that HartRAO was in the process of installing stations in Zambia, Mozambique and Namibia. 5.2.5 IAG - Ruth Neilan indicated that the IAG would be a keen role player and would provide support and assistance in realizing this project. 5.2.6 IGS/IERS/ITRF - Same as above. 5.2.7 International Agencies - Weber (BKG) commented that if there were people who would be make themselves available to act as consults in the project, it would be a good start and that funding be considered next. Support in terms of monies could possibly be received from international partners due to the need for establishing a continental network in Africa. Kumar reported on what NIMA could offer to this project. He felt that if it is started in southern Africa the scientific part could be sorted out by a working group, who would work on how to densify the various areas, then the different agencies will be brought in after the foundation phase has been determined. Merry (UCT) commented that the local partner would be the first phase and the 2nd phase would be at national level, costs would only be incurred with logistical support, which may not be a recurring amount. Mr. Wonnacott felt that this would be the point at which mapping agencies would play an important role in supporting this project over the longer term. 5.2.8 Others - Juma (Namibia) wanted to know what the basic requirement was for the establishment of an IGS station. Moore (IGS) reported that the requirements as set out in the current standards document are very general (functional requirements) but generally a dual frequency geodetic quality receiver must be used, data is to be recorded at thirty second intervals on daily basis, monumentation, regular updating of metadata (models, heights etc). Excellent stations need not excluded due to communication problems. Neilan gave a rough outline of the cost involved; monument cost (could be as much as $10,000US dollars for a triple braced, drilled to refusal monument) but can vary from country to country based on designs for first order benchmarks and current geodetic GPS practices. Receivers cost between US$10 000 and US$15 000 dollars each and computers from US$1000. Additional costs would be the installation of internet/communication lines (telephone, etc.) to import and export data. All equipment and infrastructure therefore would cost between US$20000 and US$30000. She also highlighted the advantage of having an IGS station close to an existing network is that it could be immediately picked up within the IGS network and analysed within the global reference frame. Juma wanted to know who would be providing expertise? Neilan responded that through an envisioned expression of interest that includes international organizations, groups can be identified as potential partners. This could be followed by a call for participation in the projects, a delegation of duties, gain supporting agencies and to seek acquisition of funds from participating organizations or vested agencies through proposals, grants or other mechanisms. The sustainability of the project must be one of the prime goals. Merry (UCT) informed the meeting of his involvement with the IAG Committee for Developing Countries and requested that when drawing up the project plan, consideration be given to the inclusion of a height, vertical datum and geoid component in the project. Kumar however reported on the Third working group of SIRGAS was tasked with to deal with the vertical datum. He indicated that this group was moving very slowly with this task because of the many difficulties experienced with accessing suitable data. 5.3 Proposed project plan Wonnacott pointed out that the project plan would take some time to put together and called for volunteers to be on the working group, the core being from national mapping agencies and others co-opted from other organisations. Chigumete (Zimbabwe) felt that South Africa should lead the process because of the progress which has already been made in South Africa. Neilan felt that Ghana should also attend the meeting so that they could propagate the AFREF ideas to West Africa. All the National Mapping agencies attending the meeting were voted as part of this working group with EUREF, NIMA, IGS/IAG, HartRAO and UCT (geoid) being co-opted onto the working group. A broad project plan is to be created within 3 months (end June). 6. FUTURE MEETINGS - The next meeting of CODI will be held in Adis Ababa in September 2001 at which it will be possible to discuss further developments of the AFREF project with all nations of Africa. - A Southern Africa AFREF Steering Committee meeting will be held at the Chief Directorate: Surveys and Mapping on 14 March, the day just after this meeting. 7. SUMMARY AND CLOSING The general consensus amongst participants was great support for project and that it should be realistic and manageable. Mr Wonnacott thanked all present for their contributions and in doing so closed session at 6pm. R T Wonnacott Director : Survey Services Chief Directorate : Surveys and Mapping Private Bag X10 Mowbray 7705 SOUTH AFRICA Tel: +27 21 685 4070 Fax: +27 21 689 1351