Experiment of filling the data gaps for better geoid determination: Case Study for Egypt (Africa)

The coverage of the gravity data plays an important role in the geoid determination process. Still some parts in the world have poor gravity data coverage, with sometimes, large data gaps. Egypt (representing the situation in Africa) has sparse gravity data coverage over relatively large area. This paper tries to answer which type of gravity field signals at which resolution for filling the gaps would give the best geoid determination precision. This outcome is essential for the IAG sub-commission on the gravity and geoid in Africa in order to determine the African geoid with the best possible precision. Different types of gravity field signals have been used. They are gravity, geoid undulation and deflections of the vertical. Different resolutions of these signals are tested. The computed geoid precision for each case has been determined through the least-squares collocation technique (Moritz 1980). The results are shown and comprehensively discussed.