GRACE Gravity Field Determination Using the Celestial Mechanics Approach - First Results

We present the first gravity field model AIUB-GRACE01S, which has been generated using the Celestial Mechanics Approach in an extended version. Inter-satellite K-band range-rate observations and GPS-derived kinematic positions are used to solve for the Earth's gravity field parameters in a generalized orbit determination problem. Apart from the normalized spherical harmonic (SH) coefficients, arc-specific parameters like initial conditions and pseudo-stochastic pulses are set up as common parameters for all measurement types. Our first results based on 1 year of GRACE data demonstrate that the Earth's static gravity field can be recovered with a good quality, even using EGM96 as a priori model and without accelerometer data and sophisticated background models like short-term mass variations. The use of accelerometer data and sophisticated background models will be a prerequisite for the near future, however, to further improve the inferred gravity field solutions.