Experiences with ERS-1 SAR geopositional accuracy

The German Processing and Archiving Facility (D-PAF) generates under ESA contract geocoded products on an operational basis. Up to now more then 1500 ERS-1 scenes have been geocoded. As the orbit is known very precisely and the SAR sensor operates very stably the geocoding could be performed with high accuracy from the very beginning until the present. The geocoding comprises beside the ellipsoid correction the consideration of digital terrain information. The accuracy of both corrections are presented as well as their capability for the contribution to further value added SAR products. Time series can be produced with very high precision to allow multitemporal and also multisensoral investigations. Also the generation of mosaicked data sets depends on the accuracy of the geocoding. Presently the intention of most products acquired and generated on user request is the investigation of actual effects and problems. But as all products processed at the D-PAF are archived the access to `historical´ SAR data will be possible very easily in future. This allows the monitoring and investigation of changes on the Earth considering information over a longer period of time. So geocoded data set also will play an important role for the generation of long-term series