Height Reference Surface for Africa

Determination of a high-resolution geoid for the African continent

Within the African geoid project of the International Association of Geodesy (IAG), we are working together with Prof. Abd-Elmotaal (Minia/Egypt) and Prof. Kühtreiber (Graz/Austria) on the further development of a precise geoid model for Africa.


The available data set of severity values has significant data gaps. These data gaps are filled with the EIGEN-6C4 model on a 15' x 15' grid. The window-remove-restore technique is used to generate the reduced severity anomalies with minimal variance to minimize interpolation errors, especially with these large data gaps.

 

 

The global model EIGEN-6C4, complete to degree and order 2190, is used as a reference model. Based on these reduced anomalies of varying accuracy, a 5' x 5' grid based on a least squares solution is predicted.


The reduced gridded gravity anomalies are then used to calculate the geoidundulation using the Stokes' integral with the modified Meissl core function to better combine the different wavelengths of the earth's gravity field. The gravimetric geoid obtained in the final restore step is scaled using the satellite model DIR_R5 GOCE.

The current geoid model is the AFR-geo2025.

 

 

 

Publications


Abd-Elmotaal, H. A.; Kühtreiber, N.; Seitz, K.; Grombein, T.; Heck, B.; Kutterer, H. (2026). AFRgeo2025: The New Geoid Model for Africa Implementing Moho Information. Proceedings of the 2025 Scientific Assembly of the International Association of Geodesy, Springer-Verlag. doi:10.1007/1345_2026_395 Full textFull text of the publication as PDF document
Abd-Elmotaal, H. A.; Kühtreiber, N.; Seitz, K.; Grombein, T.; Heck, B.; Kutterer, H. (2026). The AFRGDB_V3.1 updated gravity database for Africa implementing Moho information. Survey Review, 1–14. doi:10.1080/00396265.2026.2664266
Abd-Elmotaal, H. A.; Seitz, K.; Kühtreiber, N.; Grombein, T.; Heck, B.; Kutterer, H. (2025). Use of laterally varying crustal density in gravity interpolation at large data gaps: experiment for the continent Africa. Studia Geophysica et Geodaetica, 69 (2), 177–194. doi:10.1007/s11200-025-0905-5
Abd-Elmotaal, H. A.; Seitz, K.; Kuehtreiber, N.; Grombein, T.; Heck, B.; Kutterer, H. (2025). A Moho Model for Africa. Journal of Advanced Engineering Trends, 44 (2), 33– 38. doi:10.21608/jaet.2025.372553.1362
Seitz, K.; Heck, B.; Abd-Elmotaal, H. (2023). External gravitational field of a homogeneous ellipsoidal shell: a reference for testing gravity modelling software. Journal of Geodesy, 97 (6), Artkl.Nr.: 54. doi:10.1007/s00190-023-01733-1 Full textFull text of the publication as PDF document
Abd-Elmotaal, H. A.; Seitz, K.; Ashry, M.; Heck, B. (2020). Effect of great lakes on gravity reduction and geoid determination caused by unclassified DTMs: case study for Lake Victoria, Africa. Journal of geodesy, 94 (10), Art.-Nr.: 97. doi:10.1007/s00190-020-01410-7
Abd-Elmotaal, H. A.; Kühtreiber, N.; Seitz, K.; Heck, B. (2020). The New AFRGDB_V2.2 Gravity Database for Africa. Pure and applied geophysics, 177 (9), 4365–4375. doi:10.1007/s00024-020-02481-5
Abd-Elmotaal, H. A.; Seitz, K.; Kühtreiber, N.; Heck, B. (2019). AFRgeo_v1.0: A Geoid Model for Africa. Karlsruher Institut für Technologie (KIT). doi:10.5445/IR/1000097013 Full textFull text of the publication as PDF document
Abd-Elmotaal, H. A.; Seitz, K.; Kühtreiber, N.; Heck, B. (2019). Evaluation of the African gravity database AFRGDB_V1.0. International Association of Geodesy (IAG) symposium “Gravity, Geoid and Height Systems 2016”, GGHS 2016; Thessaloniki; Greece; 19 September 2016 through 23 September 2016. Ed.: R. Barzaghi, 87–92, Springer. doi:10.1007/1345_2017_16
Abd-Elmotaal, H. A.; Seitz, K.; Kühtreiber, N.; Heck, B. (2016). Establishment of the gravity database AFRGDB_V1.0 for the African Geoid. IGFS 2014 : Proceedings of the 3rd International Gravity Field Service (IGFS), Shanghai, China, June 30 - July 6, 2014. Ed.: S. Jin, 131–138, Springer. doi:10.1007/1345_2015_51
Abd-Elmotaal, H. A.; Seitz, K.; Abd-Elbaky, M.; Heck, B. (2016). Tailored Reference Geopotential Model for Africa. IAG 150 Years : IAG Scientific Assembly in Postdam, Germany, September 1-6, 2013. Ed.: C. Rizos, 383–390, Springer-Verlag. doi:10.1007/1345_2015_84
Prof. Dr.-Ing. Hansjörg Kutterer
Prof. Dr.-Ing. Hansjörg Kutterer
Úniversity Professor, Member of the Institute Management Board

+49 721 608-43674hansjoerg kutterer ∂does-not-exist.kit eduwww.gik.kit.edu/mitarbeiter_kutterer_hansjoerg.php11201.90 Campus Süd

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Prof. Hussein A. Abd-Elmotaal

Professor of Surveying and Geodesy, Minia University, Egypt

Dr.-Ing. Thomas Grombein
Dr.-Ing. Thomas Grombein

+49 721 608-42304grombein ∂does-not-exist.kit edu11401.90 Campus Süd