Parameter sensitivity of TOPIX orbit and derived mean sea level to DORIS stations coordinates

Abstract When determining precise orbits from altimetric satellites, the choice of the terrestrial reference frame is a key issue but still an open scientific topic. The terrestrial reference frame realization choice in the precise orbit determination processing will usually lead to systematic effects coming from the adoption of translations, scale factor and rotations but also others effects more difficult to assess, coming from a possible erroneous choice of a station coordinate. The goal of this paper is to try to characterize the effect of an erroneous individual station coordinate in vertical and horizontal components on the satellite orbit determination (characterization of the error, order of magnitude, consequences assessment of the on derived oceanographic products). Simulations have been realized at Institut Geographique National using the GIPSY/OASIS software from actual TOPEX DORIS data. These studies show that the stations whose latitude are close to the orbit inclination have the largest effect on the orbit error. These simulations will also help us to better estimate the required accuracy of a new tracking station. Additionally the study has been extended to try to predict the future uncertainty in the mean sea level determination in the 2000–2010 period derived for the present accuracy of the ITRF97 coordinates and velocities. Present uncertainties in the ITRF97 realization will create systematic errors in the TOPEX derived mean sea level at the 1 mm level in 2010.