Abstract
In the framework of the African Geoid Project, the currently available gravity data set contains many significant gaps allover the continent. A possible way to fill in these gaps before the geoid computation process, is to use a global geopotential model which best fits the African gravity field. Hence, the aim of this paper is to create a tailored reference geopotential model for Africa to be used to fill the gravity data gaps with reasonable values. With the ongoing improvement of the data base, this tailored model will also be updated iteratively. The remove-restore technique has been applied using a newly compiled \(30^{{\prime\prime}}\times 30^{{\prime\prime}}\) Digital Height Model for Africa based on SRTM. As global geopotential reference model serves EGM2008 which shows similar behaviour for Africa like GRACE/GOCE derived models. The local and global data sets, in terms of topographically-isostatically reduced gravity anomalies, are merged and used to estimate by three different techniques the potential coefficients of the tailored reference models for Africa. The used harmonic analysis techniques are the FFT technique, the least-squares technique and the Gauss-Legendre numerical integration technique. The results show that the tailored models computed within this investigation provide significantly smaller reduced anomalies (about 50 %) than those of EGM2008 or models derived from the GRACE and GOCE satellite missions for the African continent.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
References
Abd-Elmotaal H (2004) An efficient technique for harmonic analysis on a spheroid (ellipsoid and sphere). VGI 3(4):126–135
Abd-Elmotaal H (2007) Reference geopotential models tailored to the Egyptian gravity field. Boll Geod Sci Affini 66(3):129– 144
Abd-Elmotaal H, Kühtreiber N (2003) Geoid determination using adapted reference field, seismic Moho depths and variable density contrast. J Geod 77(1–2):77–85
Abd-Elmotaal H, Kühtreiber N (2014) Automated gross error detection technique applied to the gravity database of Africa. General Assembly of the European Geosciences Union, Vienna, Austria, 27 April– 2 May 2014
Abd-Elmotaal H, Makhloof A (2013) Gross-errors detection in the shipborne gravity data set for Africa. Geodetic Week, Essen, 8–10 Oct 2013
Abd-Elmotaal H (2015) Validation of GOCE models in Africa. Newton’s Bull 5 (in press)
Abd-Elmotaal H, Seitz K, Abd-Elbaky M, Heck B (2013) Comparison among three harmonic analysis techniques on the sphere and the ellipsoid. J Appl Geod 1–18. Doi:10.1515/jag-2013-0008.
Bruinsma S, Förste C, Abrikosov O, Marty JC, Rio MH, Mulet S, Bonvalot S (2013) The new ESA satellite-only gravity field model via the direct approach. Geophys Res Lett 40(14):3607–3612. Doi:10.1002/grl.50716.
Colombo O (1981) Numerical methods for harmonic analysis on the sphere. Ohio State University, Department of Geodetic Science and Surveying, Report 310
Farr T, Rosen P, Caro E, Crippen R, Duren R, Hensley S, Kobrick M, Paller M, Rodriguez E, Roth L, Seal D, Shaffer S, Shimada J, Umland J, Werner M, Oskin M, Burbank D, Alsdorf D (2007) The shuttle radar topography mission. Rev Geophys 45:RG2004. Doi:110.1029/2005RG000183.
Forsberg R (1984) A study of terrain reductions, density anomalies and geophysical inversion methods in gravity field modelling. Ohio State University, Department of Geodetic Science and Surveying, Report 355
Förste C, Flechtner F, Schmidt R, Stubenvoll R, Rothacher M, Kusche J, Neumayer KH, Biancale R, Lemoine JM, Barthelmes F, Bruinsma J, König R, Meyer U (2008) EIGEN-GL05C – A new global combined high-resolution GRACE-based gravity field model of the GFZ-GRGS cooperation. General Assembly of the European Geosciences Union, Vienna, Austria, 13–18 April 2008
Heck B, Seitz K (1991) Harmonische Analyse. Technical Report, Geodetic Institute, University of Karlsruhe
Hofmann-Wellenhof B, Moritz H (2006) Physical geodesy. Springer, NewYork
Merry C (2003) The African geoid project and its relevance to the unification of African vertical reference frames. 2nd FIG Regional Conference Marrakech, Morocco, 2–5 Dec 2003
Merry C, Blitzkow D, Abd-Elmotaal H, Fashir H, John S, Podmore F, Fairhead J (2005) A preliminary geoid model for Africa. A window on the future of geodesy. Springer, Berlin, pp 374– 379
Pail R, Bruinsma S, Migliaccio F, Förste C, Goiginger H, Schuh W, Höck E, Reguzzoni M, Brockmann J, Abrikosov O, Veicherts M, Fecher T, Mayrhofer R, Krasbutter I, Sansò F, Tscherning C (2011) First GOCE gravity field models derived by three different approaches. J Geod 85(11):819–843. Doi:10.1007/s00190-011-0467-x
Pavlis N (1988) Modeling and estimation of a low degree geopotential model from terrestrial gravity data. Ohio State University, Department of Geodetic Science and Surveying, Report 386
Pavlis N, Rapp R (1990) The development of an isostatic gravitational model to degree 360 and its use in global gravity modeling. Geophys J Int 100:369–378
Pavlis N, Factor J, Holmes S (2007) Terrain-related gravimetric quantities computed for the next EGM. In: Kiliçoğlu A, Forsberg R (eds) Proceedings of the 1st international symposium IGFS: gravity field of the Earth, Istanbul, Turkey, 2006, Harita Dergisi, Special Issue 18, pp 318–323
Pavlis N, Holmes S, Kenyon S, Factor J (2012) The development and evaluation of the earth gravitational model 2008 (EGM2008). J Geophys Res 117:B04406. Doi:10.1029/2011JB008916.
Row L, III, Hastings D (1995) Terrain base global terrain model. National Geophysical Data Center and World Data Center-A for Solid Earth Geophysics, Boulder, Colorado URL ftp://ftp.ngdc.noaa.gov/Solid_Earth/Topography/tbase_5min/tbase.txt.
Rummel R, Rapp R, Sünkel H, Tscherning C (1988) Comparisons of global topographic/isostatic models to the earth’s observed gravity field. Ohio State University, Department of Geodetic Science and Surveying, Report 388
Sünkel H (1985) An isostatic earth model. Ohio State University, Department of Geodetic Science and Surveying, Report 367
Tapley B, Ries J, Bettadpur S, Chambers D, Cheng M, Condi F, Poole S (2007) The GGM03 mean earth gravity model from GRACE. American Geophysical Union, Fall Meeting, San Francisco, 10–14 Dec 2007
Weber G, Zomorrodian H (1988) Regional geopotential model improvement for the Iranian geoid determination. Bull Geod 62:125–141
Wenzel H (1998) Ultra high degree geopotential models GPM98A, B and C to degree 1800 tailored to Europe. Rep Finnish Geodetic Institute 98(4):71–80
Acknowledgements
The authors would like to thank four anonymous reviewers, as well as the Editor-in-Chief, for their valuable comments, which helped to improve the manuscript. Financial support of the STDF/ DAAD is kindly acknowledged.
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2015 Springer International Publishing Switzerland
About this paper
Cite this paper
Abd-Elmotaal, H.A., Seitz, K., Abd-Elbaky, M., Heck, B. (2015). Tailored Reference Geopotential Model for Africa. In: Rizos, C., Willis, P. (eds) IAG 150 Years. International Association of Geodesy Symposia, vol 143. Springer, Cham. https://doi.org/10.1007/1345_2015_84
Download citation
DOI: https://doi.org/10.1007/1345_2015_84
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-319-24603-1
Online ISBN: 978-3-319-30895-1
eBook Packages: Earth and Environmental ScienceEarth and Environmental Science (R0)