On the Effect of Reference Frame Motion on InSAR Deformation Estimates

For processing of interferometric synthetic aperture radar (InSAR) data, precise satellite orbits are required. These orbits are given in a reference frame with respect to which tectonic plates perform a relative motion. Neglecting this motion can cause temporally increasing baseline errors that induce large scale error ramps into the interferometric phase. The amount of error depends on the geographical location and is evaluated globally for the ENVISAT orbit. Predicted biases of deformation estimates can reach up to 7 mm/a in some areas. Whereas these biases are not separable from actual deformation signals by spatio-temporal correlation properties, they are well predictable and can easily be accounted for. A most simple correction approach consists in compensating the plate motion by modifying orbital state vectors, assuming a homogeneous velocity for the whole plate. This approach has been tested on Persistent Scatterer Interferometry (PSI) results over the area of Groningen, the Netherlands.