Surface current measurements by spaceborne along-track inSAR - terraSAR-X, tanDEM-X, and future systems

Within 28 years since the first demonstration of ocean current measurements by along-track interferometric synthetic aperture radar (along-track InSAR) and almost eight years since the launch of TerraSAR-X, the first satellite with experimental along-track interferometry (ATI) capabilities, a number of interesting ATI experiments and theoretical studies have been carried out, and we have learned a lot about properties of ATI data, optimal processing techniques, and the dependence of the quality of ATI-derived current fields on instrument parameters such as InSAR time lag and incidence angle. This paper gives an overview of some ATI achievements of TerraSAR-X and the twosatellite formation TanDEM-X and discusses the potential capabilities of dedicated InSAR satellites for ocean applications that may be launched within the coming years.