Abstract
By solving the Laplace differential equation in the elliptic coordinates, we apply the general solution of the equation obtained by the method of separating the variables, then by solving the problem in the ellipse we calculate the normal potential of the earth. Then, using the Sumigliana formule, we calculate the normal gravity field for the coordinates of one degree of the earth's surface, and by subtracting the normal gravitational field components, we obtain the global normal gravity field for the specified coordinates in the EGM96 global model. Then, with the help of coding in the Matlab program, we compute the normal gravity field for the GRS 1967 and GRS 1980 and GRS 1930 models in the geodesic coordinates, and finally compare the results of these models.