Performance Analysis of Satellite Missions for Multi-Temporal SAR Interferometry

Abstract

Multi-temporal InSAR (MTI) applications pose challenges related to the availability of coherent scattering from the ground surface, the complexity of the ground deformations, atmospheric artifacts, and visibility problems related to ground elevation. Nowadays, several satellite missions are available providing interferometric SAR data at different wavelengths, spatial resolutions, and revisit time. A new and interesting opportunity is provided by Sentinel-1, which has a spatial resolution comparable to that of previous ESA C-band sensors, and revisit times improved by up to 6 days. According to these different SAR space-borne missions, the present work discusses current and future opportunities of MTI applications in terms of ground instability monitoring. Issues related to coherent target detection, mean velocity precision, and product geo-location are addressed through a simple theoretical model assuming backscattering mechanisms related to point scatterers. The paper also presents an example of a multi-sensor ground instability investigation over Lesina Marina, a village in Southern Italy lying over a gypsum diapir, where a hydration process, involving the underlying anhydride, causes a smooth uplift and the formation of scattered sinkholes. More than 20 years of MTI SAR data have been processed, coming from both legacy ERS and ENVISAT missions, and latest-generation RADARSAT-2, COSMO-SkyMed, and Sentinel-1A sensors. Results confirm the presence of a rather steady uplift process, with limited to null variations throughout the whole monitored time-period.

Pre-Collapse Space Geodetic Observations of Critical Infrastructure: The Morandi Bridge, Genoa, Italy

“…The synergistic use of CSK, SNT and Envisat played a key role in our study. The SNT data have been acquired at a rate nearly three times faster than CSK (6 days repeat vs 16 days repeat for SNT and CSK respectively), while the large CSK orbital tube and better CSK spatial resolution (3 x 3 meters vs. 4 x 22 meters range and azimuth resolution for CSK and SNT respectively) allowed us to better geolocate the analyzed scatterers in the three-dimensional space by a factor of three, as confirmed by independent studies [32,33]. The SNT tight orbital tube introduces a further level of difficulty when geolocating the observed scatterers located on the northern/southern side of the bridge.…”

Unraveling Spatial and Temporal Heterogeneities of Very Slow Rock-Slope Deformations with Targeted DInSAR Analyses

“…), snowmelt in this sector usually starts around the end of May, later than usually observed at the valley floor. In the snowmelt period, major portions of the slopes are still covered by snow, hampering DInSAR processing [12,37,38] and accurate quantification of snowmelt contributions to displacements.…”

Long-Term Deflection Monitoring for Bridges Using X and C-Band Time-Series SAR Interferometry

“…(1). According to [31], the residual height estimation using multi-temporal interferometric technique is a function of the number of scenes, the geometrical parameters such as a standard deviation of the baseline, slant range distance, and incidence angle, and the radiometric parameters such as wavelength and standard deviation of phase. As shown in Figures 5 and 6, the short wavelength and large orbital tube diameter (~2000 m) of CSK allow the accurate height estimation and geo-relocation.…”