Satellite Altimetry in the Czech Republic: Status 2007

The aim of this presentation is to inform about works in satellite altimetry in the Czech republic during the last 15 years and to provide an outline of the results. The results come from two groups, one is from CEDR (Center for Earth Dynamics Research) and the second is from Military Geographic and Hydrometeorologic Office. We also cooperated with NOAA and NIMA. We worked out-and used repeatedly-a method based on long-term averaged crossover altimetry data (from missions ERS 1, 2, Envisat and Geosat). With these (generated from orbits using tested geopotential models) we computed Latitude Lumped Coefficient (LLC) discrepancies, compared them to the LLC errors projected from the covariance matrices of these models and from the comparison assessed the accuracy of the gravity models. We used single and dual satellite crossover data (SSC and DSC) to refine gravity field models. We also utilized the DSC between low and higher altimetry orbits to detect possible offsets among the terrestrial reference frames of the altimetry missions involved. The potential of geoid W0 has been derived by means of combining altimetry, levelling, GPS height and gravity data and in turn, an offset between different world height systems has been estimated. We also studied the theory of bistatic satellite altimetry, namely the distribution of reflecting points and the accuracy of their determined surface heights and most recently the determination of the specular reflecting points on the Earth represented not only by a sphere but also an oblate ellipsoid.