Benchmarking and inter-comparison of Sentinel-1 InSAR velocities and time series

Abstract

Different InSAR algorithms and methods produce velocities and times series that are not identical, even using the same data for the same area. This inconsistency can cause confusion and be a barrier to uptake and widespread use of the data in the commercial sector. With the widespread availability of Sentinel-1 SAR data and a suite of new algorithms in the commercial and academic sectors, it is timely to develop a method for comparison of different results. In this study, we focus on developing and testing an independent and robust methodology for assessment of different InSAR processing results. Our proposed method is adapted from the Terrafirma Process Validation project; we compare geocoded line-of-sight velocities and time series, density and coverage, as well as some qualitative metrics. We use Sentinel-1 data from an area in Glasgow (UK) processed using 4 different approaches modified RapidSAR, SqueeSAR, GAMMA-IPTA and conventional StaMPS. The main areas of ground motion are detected using all approaches, with the average standard deviation of velocity differences for all intercomparison pairs in all polygons equal to 1.1 mm/yr. Sentinel-1 InSAR therefore provides comparable results that are independent of processing approaches. However, there are considerable differences in some aspects of the results, in particular in their density and coverage. We discuss the reasons for these differences and suggest a framework for validation that could be used in future national or pan-national ground motion services.

Spatio-temporal analysis and volumetric characterization of interferometric synthetic aperture radar-observed deformation signatures related to underground and in situ leach mining

“…Our results are shown in Table 4 with uncertainties taken from standard deviation measurements and uncertainty error propagation for our InSAR and GPS estimates, respectively. After comparison, we find a mean difference of 1.2 mm/year between InSAR-observed measurements of surface deformation and GPS-observed measurements of surface deformation due to subsurface processes, which is in good agreement with the quantified Sentinel-1 uncertainty from a benchmark study 17 …”

“…We use an exponential geostatistical model covariance matrix with characteristic distance scales of ly=1700 m along strike of 45°N and lx=500 m across strike of 45°N to account for the geometry of the mining and corresponding deformation signal. Sentinel-1 has been shown to have measurement uncertainty of roughly 1.1 mm/year 17 . We use this value to assign an inherent data uncertainty to our measurements after verification with our own GPS validation analysis (Appendix B).…”

“…Sentinel-1 has been shown to have measurement uncertainty of roughly 1.1 mm∕year. 17 We use this value to assign an inherent data uncertainty to our measurements after verification with our own GPS validation analysis (Appendix B). We assign priors to our volumetric strain rates.…”

Ground and Satellite-Based Methods of Measuring Deformation at a UK Landslide Observatory: Comparison and Integration

“…The mean line-of-sight component of the mean subsidence rate measured with the 132 ascending frame is 2.7 mm/year, while with the 081 descending and 154 descending frames it is 7.7 mm/year and 7.5 mm/year, respectively. The nominal error on these values is 1 mm/year [39]. We selected the pixels that are closest to individual pegs and compared the displacement of the ERT pegs with the InSAR measurements.…”

Ground motion baseline analysis of the Cheshire UK GeoEnergy Observatory

“…InSAR-based monitoring is less expensive, more frequent and less invasive than standard geodetic monitoring techniques and can provide appropriate monitoring at site scale 6 . Although InSAR application over geoenergy sites is well documented 7 – 9 , as of today no work has studied ground conditions ahead of the construction and exploitation of a site. This work documents baseline monitoring undertaken by BGS to characterise ground motion in the area of the Cheshire Observatory ahead of facility contruction.…”