Development of finite element models for the earth's gravity field phase i: macro gravity model for satellite orbit integration

As alternatives to lengthy globally valid series representations of the geopotential, piecewise modeling for the gravity field is investigated. A degree 23 spherical harmonic representation is replaced by 1500 local gravity functions within the spherical shell from 1 to 1.2 earth radii. Worst case acceleration errors enter in the 7th significant digit, computational speed is improved by an order of magnitude. (Author).