Multi-track PS-INSar: Datum connection and reliability assessment

InSAR data acquired from independent overlapping tracks can be exploited for a reliability assessment of the Persistent Scatterer InSAR (PS-InSAR) technique. Here we present a mathematical framework for the datum connection of multiple tracks, simultaneously evaluating the precision and reliability of PS-InSAR estimates. This datum connection can be subdivided in two steps. Firstly, the PS locations are converted to a common radar coordinate system: the geometry of the so-called 'master track'. The second step consists of the connection of the PS-InSAR parameter estimates (velocities, displacements, heights). Since each track has its own reference PS, the transformation is parameterized as a translation, which can be optionally extended with a trend in range and azimuth direction due to unmodeled residual effects. Multi-track datum connection has been applied in the Groningen region, the Netherlands, which is affected by subsidence due to gas extraction with displacement rates up to 7 mm/year. The main reservoir is (partly) visible in 6 independent overlapping ERS tracks (ascending and descending). Utilizing the different viewing geometries, the connected PSInSAR estimates could be further decomposed into horizontal and vertical displacement rates.