Potential of a C-band SAR mission with 12-day repeat cycle to derive ice surface velocity with interferometry and offset tracking

The goal of this contribution is the assessment of the potential of a C-band SAR mission with repeat-pass interval of 12 days - as the intended European satellite system Sentinel-1 - to derive ice surface velocity using SAR interferometry (InSAR) and offset-tracking. For this purpose we investigated ERS-1 SAR data acquired during the ice missions in 1992 and 1994 in 3-day repeat- orbits at Nordaustlandet in the northeast Svalbard archipelago. In 12-days winter InSAR pairs phase decorrellation is mainly observed in areas of high strain rates and, in certain cases, because of snow melting or redistribution through snowfall or wind. Velocity maps derived from these image pairs were found useful to enhance in regions of slow glacier flow the mapping of the surface ice-flow divides previously determined from optical imagery and topographic information. Range-azimuth offset-tracking investigations suggest that the expected error of this method is on the order of 50 m/year and that spatial coverage is generally satisfactory. Application of dual-azimuth offset- tracking, use of HH polarization and enhanced spatial resolution, feasible with Sentinel-1, could enhance the expected error.