A first attempt at time-variable gravity recovery from CHAMP using the energy balance approach

Using the principle of energy conservation has been considered for gravity field determination from satellite observations since the early satellite era. CHAMP is the first satellite to which the energy balance approach can be usefully applied, now that near-continuous orbit tracking by GPS is available, aided by accelerometry. The feasibility of this approach has recently been demonstrated. The abundance and quality of CHAMP data should allow us to monitor the Earth’s gravity field over time. In this paper we will investigate the strengths and weaknesses of the energy balance approach for purposes of time-variable gravity field recovery. The quality of the required orbit is discussed in terms of GPS data, accelerometry and orbit processing. Also the quality and the physical relevance of the output gravity field time-series will be analyzed.