Laying the foundations for GGOS-Africa
Radcliffe, Jack; de Witt, Aletha; Botha, Roelf; Baki, Paul
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Abstract
This record documents the foundations and vision of the GGOS-Africa initiative, presented at the first South African Geodesy Working Group Workshop (2025). The project, led by Dr Jack F. Radcliffe with contributions from A. De Witt, P. Baki, and R. Botha, is supported by UK Research and Innovation (UKRI) and the Science and Technology Facilities Council (STFC) through the Africa–UK physics partnership. The Global Geodetic Observing System (GGOS) provides a framework for monitoring the Earth’s shape, gravity field, and rotation, with critical applications across agriculture, climate services, disaster management, infrastructure, energy, and astronomy. While Africa has existing geodetic initiatives, significant disparities remain in infrastructure and access to data. GGOS-Africa aims to unify and strengthen geodetic efforts across the continent, complementing ongoing programmes such as AFREF and UN-GGIM: Africa. The project (2025–2027) pursues five main goals: Assess Africa’s geodetic infrastructure and resources. Develop strategic infrastructure plans through simulations and modelling. Provide training and capacity-building opportunities for early-career African geodesists. Establish GGOS-Africa as a formal affiliate organisation coordinating continental activities. Promote awareness of geodesy’s role in sustainable development among policymakers. Activities include infrastructure assessments, simulation-based planning (e.g. VLBI and GNSS network development), and exploration of synergies with astronomy and space science. A phased governance model is proposed, ensuring broad African participation and equitable regional development. The first GGOS-Africa workshop is scheduled for 2026, with a long-term plan to ensure sustainability through human capital development, international partnerships, and funding expansion. This document provides an overview of the project’s strategic vision, technical foundations, and roadmap toward establishing GGOS-Africa as a key regional affiliate within the global geodetic community.
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Dr Jack F. Radcliffe UK SKAO Regional Centre Science Community Director Lead - the GGOS-Africa project Laying the foundations for GGOS-Africa Key contributors: A. De Witt (DSTI) P. Baki (Technical University of Kenya) R. Botha (SARAO/HartRAO)
JACK F. RADCLIFFE 01/10/2025 SOUTH AFRICAN GEODESY WORKING GROUP - WORKSHOP #1 / 15 Geodesy & its hidden impact Geodesy studies the Earth’s dynamic size, shape, and gravitational field, playing a crucial role in many scientific disciplines with far-reaching societal impacts. Needed for anything needing geospatial information including: • Agriculture •Aviation And Drones • Biodiversity, Ecosystems And Natural Capital • Climate Services •Consumer Solutions, Tourism And Health • Earth System Science •Emergency Management And Humanitarian Aid •Energy And Raw Materials •Environmental Monitoring • Fisheries And Aquaculture • Forestry •Infrastructure •Insurance And Finance •Maritime And Inland Waterways •Rail •Road And Automotive • Space & Astronomy • Time Measurement And Synchronization • Urban Development And Cultural Heritage 2 Earth's geoid as seen by GOCE
JACK F. RADCLIFFE 01/10/2025 SOUTH AFRICAN GEODESY WORKING GROUP - WORKSHOP #1 / 15 (Space) geodesy 3 Parameter VLBI GNSS DORIS SLR ICRF Nutation Polar motion UT1 Length-of-day Subdaily ERPs ERP oceantide amplitudes Coordinates/velocities (ITRF) Geocentre Gravitational field Satellite orbits LEO satellite orbits Ionosphere Troposphere Time synchronisation Credit: UN-GGCE
JACK F. RADCLIFFE 01/10/2025 SOUTH AFRICAN GEODESY WORKING GROUP - WORKSHOP #1 / 15 Global Geodetic Observing System (GGOS) 4 A GGOS Affiliate is a national or regional organisation that coordinates geodetic activities in that country or region. Milestones: • 1998 - Birth of GGOS •2017 - Establish Affiliate GGOSJapan •2021 - Establish Affiliate GGOS D-A-CH •2024 - Establish Affiliate GGOS IberAtlantic • 2025 - GGOS-Africa(?) GGOS is the organisation responsible for the advancement of geodesy. GGOS Core Sites co-locate the major observation techniques. GGOS structure
JACK F. RADCLIFFE 01/10/2025 SOUTH AFRICAN GEODESY WORKING GROUP - WORKSHOP #1 / 15 Do we need a GGOS-Africa? The global and regional situation in Africa 5 DORIS SLR GNSS VLBI The distribution of VLBI, SLR, GNSS, and DORIS stations in Africa that contributed to ITRF2020–u2023. Credit: Altamimi et al., 2020 (left) and https://itrf.ign.fr/ (right).
JACK F. RADCLIFFE 01/10/2025 SOUTH AFRICAN GEODESY WORKING GROUP - WORKSHOP #1 / 15 Do we need a GGOS-Africa? Disparity between global and regional infrastructure & core stations 6 Distribution of known GNSS geodetic and reference receivers in and around Africa. Some receivers/networks are privately owned and data is not freely available. NOAA/ CORS and NIGNET were shut down 2017 and 2020. Credit: Baki et al., 2023 . Known GNSS receivers in Africa GNSS receivers contributing to GGOS Credit: https://itrf.ign.fr/ Credit: GGOS GGOS core-sites (have all 4 techniques co-located)
JACK F. RADCLIFFE 01/10/2025 SOUTH AFRICAN GEODESY WORKING GROUP - WORKSHOP #1 / 15 The GGOS-Africa project • UK Research and Innovation (UKRI) & Science and Technologies Facilities Council (STFC) provided 2-yr seed funding (~270k GBP) through the Africa-UK physics partnership collaborative research projects fund to start building the foundations of GGOS-Africa. • Project from 02/2025–02/2027 and is a collaboration of the following institutes: 7
JACK F. RADCLIFFE 01/10/2025 SOUTH AFRICAN GEODESY WORKING GROUP - WORKSHOP #1 / 15 Our vision and goals Our vision: We intend to establish GGOS-Africa and support both new and existing geodetic initiatives throughout Africa, thereby promoting developments at global, regional, and national levels. *Not a replacement for ongoing initiatives (e.g., AFREF) but instead a forum to network, unify and create common goals in advancing geodetic initiatives across the continent. Our goals: 1. Assessing Africa's geodetic infrastructure and resources. 2. Developing strategic infrastructure plans using simulations. 3. Training early-career African geodesists through workshops and collaborations. 4. Establishing GGOS-Africa to help coordinate geodetic activities. 5. Raising awareness among policymakers about the role of geodesy in sustainable development. 8 More information at the project website: https://www.jb.man.ac.uk/GGOS-Africa/
JACK F. RADCLIFFE 01/10/2025 SOUTH AFRICAN GEODESY WORKING GROUP - WORKSHOP #1 / 15 Infrastructure assessment and planning •Infrastructure and capacity assessment: Detailed inventory of existing geodetic and computational infrastructure and operational status, and country-level geospatial reference systems and capacity (surveys and site visits, UN-GGCE Factbooks, UN:GGIM-Africa/AFREF). •Simulation models and geospatial analysis: Analyse current infrastructure gaps and predict the impact of and best locations for new geodetic infrastructure. •Strategic infrastructure development plan: Outlines recommended locations for new infrastructure and identifies priorities for infrastructure enhancement and human capital development. 9 Remote GeoStations 9
JACK F. RADCLIFFE 01/10/2025 SOUTH AFRICAN GEODESY WORKING GROUP - WORKSHOP #1 / 15 Summary • The Africa-GGOS project has been founded to accelerate the improvement of geodetic infrastructure, capabilities and human capital across the African continent. • To achieve this, work has begun on the following initiatives: -An understanding of the current gaps in geodetic infrastructure across the continten -Founding of the official GGOS-Africa affiliate organisation. - Close collaboration and input from all stakeholders from government to academia, and institutions across Africa, such as AFREF, RCMRD etc. and international institutions such as the UN and GGOS/IAG/IUGG. -Sustained, stable funding to continue GGOS-Africa. If you wish to join the initiative, feel free to contact jack.radcliffe [at] manchester.ac.uk 15
