Abstract— The geoid is the fundamental surface that defines the figure of the Earth. It is approximated by mean sea level and undulates due to spatial variations in the Earth’s gravity field.
The solution, that considers a global geopotential model (GM), gravity anomalies (Δg), and topographic effects, is used to determine the gravimetric geoid undulation. The EGM96 global geopotential model to degree 360 was used in order to determine the long wavelength effect of the geoid surface. By applying the remove-restore technique the geoid undulations were determined by combining a geopotential model, mean free-air gravity anomalies and height in a Digital Elevation Model (DEM). The long wavelength effects from a geopotential model and short wavelength effects from the topography are mathematically removed from the observed gravity anomalies in this technique. The Stoke’s formulation of the residual parts of the gravity anomalies yields the medium wavelength of the geoid height. The geoidal height of a point is determined by restoring the long and short wavelength components. If the area for determining local geoid is chosen small and is considered as planar, it can be divided into M by N grids while distances Δx and Δy are the grid intervals. The geoid undulations can be calculated from Fast Fourier Transform (FFT) solutions of the Kernel functions of the gridded gravity anomalies and distances.
This paper deals with the precision geoid determination by a gravimetric solution in around the Oman Gulf. The size of the study area is about 600 km by 660 km. A number of data files were compiled for this work, containing now more than 88000 point gravity data on ocean areas. The EGM96 global geopotential model to degree 360 was used in order to determine the long wavelength effect of the geoid surface. By applying the remove-restore technique the geoid undulations were determined by combining a geopotential model, mean free-air gravity anomalies.
Keywords— Gravity, Geoid, Geopotential Model, FFT, Remove-restore technique Stokes-Kernel
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