On multi technique precise orbit determination for SWOT with respect to altimetry applications.

SWOT (Surface Water and Ocean Topography) is a recently launched international satellite mission developed in close collaboration between CNES and NASA space agencies aimed to reach a new level of accuracy in observing global water systems of the Earth. In order to meet the high accuracy requirements of the mission most precise determined orbits are crucial. Therefore we generate orbits using dynamic Precise Orbit Determination (POD) with multiple techniques, i.e. DORIS, GPS and SLR with the aim of generating a highly precise orbit with minimal residual error. For this purpose, single technique orbits are generated based on DORIS and GPS only, using SLR for validation only. For quality analysis we evaluate the estimated parameters of the dynamic POD and perform orbit comparisons to external orbit solutions. Subsequently, to reduce technique-specific effects of the dynamic modeling, we generate a combined orbit solution based on DORIS and GPS, and estimate the reference points of the observation techniques on the satellite to examine the calibration by the manufacturer. Based on the generated orbit solutions altimetry evaluation such as cross-over point analysis is made and discussed.