Detailed gravimetric geoid for the Egyptian south-western desert

Abstract

Different gravimetric geoid solutions were carried out for the south-western Egyptian desert. A set of 2682 measured gravity stations were available for this investigation. The discrete gravity data are reduced to the geoid through the free-air reduction. Also terrain reduction is performed using a set of fine 30″ × 30″ and coarse 3′ × 3′ Digital Height Models for the test area. Different earth's geopotential models were used for the removing of the reference field. The geoid computations were performed in the space domain using the discrete Stokes integration technique and in the spectral domain using the spherical 2-D FFT technique. For both techniques, the reduced gravity anomalies are gridded on a 3′ × 3′ geographical grid using the least-squares interpolation technique with local covariance functions. A broad comparison among the different geoid solutions is made. The effect of the inner zone densification is in the order of about 2 cm. The effect of the spherical 2-D FFT approximation is mostly less than 1 cm.