Analysis of one month of CHAMP state vector and accelerometer data for the recovery of the gravity potential

International audienceThe energy conservation method is based on knowledge of the state vector and measurements of nonconservative forces. This is or will be provided by CHAMP, GRACE and GOCE. Here the analysis of one month of CHAMP state vector and accelerometer data is described. The energy conservation method is used to estimate the gravity potential at satellite altitude. When doing so we consider the tidal potential from the sun and the moon, the explicit time variation of the gravity potential in inertial space and loss of energy due to external forces. Fast Spherical Collocation have been used to estimate a gravity field model to degree and order 90, UCPH2002 04. This gravity field model is compared to EGM96 and EIGEN-2. The largest differences with respect to EGM96 are found at those places where the gravity data used to determine EGM96 had the largest uncertainty. EIGEN-2 and UCPH2002 04 are similar, though there are some differences in Antarctica and Central Asia