AFRGDB_V2.0: The Gravity Database for the Geoid Determination in Africa
The available gravity data set for Africa consists of land point gravity data as well as shipborne and altimetry derived gravity anomalies data, but suffers from a lot of significant large gaps. The establishment of the AFRGDB_V2.0 gravity database for Africa has been carried out using a weighted least-squares prediction technique. The land gravity data got the highest precision, while the shipborne and altimetry gravity data got a moderate precision. The data gaps are filled by an underlying grid utilizing the GOCE Dir_R5 model, getting the lowest precision within the prediction technique. The window technique has been used to produce the best reduced anomalies before the interpolation process. The AFRGDB_V2.0 gravity database on a uniform 5′× 5′ grid has been established by the developed process and has been validated using real data. This validation proved that the established gravity database for Africa has an internal precision of about 5.5 mgal, and an external accuracy of about 7 mgal.
KeywordsAfrica Geoid determination Gravity Least-squares prediction Window technique
This project was supported financially by the Science and Technology Fund (STDF), Egypt, Grant No. 7944. The authors would like to thank Dr. Sylvain Bonvalot, Director of the Bureau Gravimétrique International (BGI), for providing part of the used data set for Africa. The support by the International Association of Geodesy (IAG) and the International Union of Geodesy and Geophysics (IUGG) is kindly acknowledged. The authors would like to thank the editor of the current paper and two anonymous reviewers for their useful comments.
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