An Integrated Global/Regional Gravity Field Determination Approach based on GOCE Observations

GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) is a dedicated satellite gravity field mission to be launched in the year 2006. The payload of GOCE will consist of a GPS receiver for a precise orbit determination and for recovering the long and medium spectral part of the gravity field. The high resolution spectral part of the gravity field will be derived by in-orbit gravity gradients in three spatial directions measured by a gravity gradiometer consisting of six three-axis accelerometers. In this article an integrated gravity field recovery procedure is presented that allows to determine a global gravity field solution with high long and medium wavelength accuracy and to improve this global solution in regions with characteristic gravity field features by an adapted regional recovery procedure. If necessary, several regional solutions with global coverage can be merged by means of quadrature methods to obtain an improved global solution. Simulation results are presented to demonstrate this approach. Due to the improved regionally adapted gravity field solutions this technique provides better global gravity field recovery results than calculating a spherical harmonics solution by recovering the potential coefficients directly.