SAR and SAR interferometry for geodetic applications

Kurzfassung

The use of Synthetic Aperture Radar (SAR) data for geodetic applications mature today. Satellite data are available abundantly from governmental and from industrial missions with global coverage and with very high resolution. The course gives a brief introduction to SAR interferometry and SAR imaging geometry. Then two different techniques will be presented: Persistent Scatterer Interferometry (PSI) and Imaging Geodesy. Ground motion services based on the PSI technique have been established nationwide and are currently built for the whole of Europe. Nevertheless, there is still room for improvement in many aspects, e.g., to increase the accuracy by reducing the influence of atmospheric refraction and by composing 2D and 3D deformation vectors from 1D observations. The tutorial explains the theory of PSI and some recent advances such as atmospheric phase reduction using numerical weather models. Practical examples from the German and European ground motion service are shown. Another technique that is not fully established today is to take advantage of the inherently precise geometry of SAR. By applying geodetic techniques that are standard in GNSS but not as widely used in the SAR community, objects can be located with centimeter accuracy in the TerraSAR-X image plane and with about 6 centimeter accuracy in 3D. Similar values can be achieved with Sentinel-1 data, and ESA is working on an auxiliary geodetic correction product that will be simple to use and reduce the geometric error of Sentinel-1 to a few centimeters. The tutorial covers various technical aspects of SAR geodesy, from orbit determination to solid Earth tides and weather models, and shows practical application examples for precise point positioning.