INVESTIGATION RELATED TO THE ESTABLISHMENT OF A WORLD GEODETIC SYSTEM.

Abstract : A world-wide geodetic system which will best serve the present needs of geodesy is defined by four groups of components. These are geocentric coordinates and associate variances of physical points, spherical harmonic coefficients of the geopotential, a mean earth ellipsoid, and a group of seven transformation parameters for each datum which connect the geocentric coordinates with the geodetic coordinates of that datum. The method of determination of that system is given, based on all types of presently available geodetic observations, namely, terrestrial triangulation, astronomic observations, terrestrial gravity observations, and geometric and dynamic satellite observations. For all these observations, proper mathematical models are given. In addition, all the constraints which will guarantee a unique mean earth ellipsoid are introduced. Using the specified geodetic observations in the mathematical models developed, groups of observation equations and then normal equations may be formed. The solution for the components of the world geodetic system will be the solution of the summation of these normals, properly scaled to account for different model or weighting errors in each group. Finally, the contribution of each type of data to the determination of the components of the world geodetic system as well as the overall accuracy achieved is investigated. (Author)