Integration of Corner Reflectors for the Monitoring of Mountain Glacier Areas with Sentinel-1 Time Series

• Published in: Remote sensing (Basel, Switzerland) Vol. 11; no. 8; p. 988
• Main Authors: Jauvin, Matthias, Yan, Yajing, Trouvé, Emmanuel, Fruneau, Bénédicte, Gay, Michel, Girard, Blaise
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 25.04.2019; MDPI
• Subjects: Accuracy; Anechoic chambers; Backscattering; Bands; corner reflector; Digital Elevation Models; displacement; Displacement measurement; Earth science; Environmental Engineering; Environmental Sciences; Geometrical optics; Glacial drift; glacier; Glaciers; Global positioning systems; GPS; InSAR; Interferometric synthetic aperture radar; Interferometry; Lidar; moraine; Mountains; Phase error; Radar; radar cross section; Radar cross sections; Reflectors; Remote sensing; Satellite tracking; Sentinel-1; Stability analysis; synthetic aperture radar; Target recognition; Tectonics; Time series; Visibility; France; United States > US
• ISSN: 2072-4292; 2072-4292
• DOI: 10.3390/rs11080988

Glacier flow and slope instabilities in Alpine mountain areas represent a hazard issue. Sentinel-1 satellites provide regular Synthetic Aperture Radar (SAR) acquisitions that are potentially useful to monitor these areas, but they can be affected by temporal decorrelation due to rapid changes in the surface. The application of interferometric synthetic aperture radar (InSAR) therefore seems difficult due to loss of coherence. On the other hand, Corner Reflectors (CR) can be used as coherent targets in SAR images for accurate displacement measurement thanks to their strong backscattering property and temporal stability. The use of CRs in multi-temporal InSAR analysis in Alpine mountain areas can thus be beneficial. In this study, we present a comparison between triangular and rectangular CRs, based on Radar Cross Section (RCS) measurements in an anechoic chamber and on long-term experiments over the Argentière glacier and the surrounding slopes and moraine. The visibility in both summer and winter of 10 CRs installed on the test site was investigated. As this area is exposed to heavy precipitation including snow falls, two perforated CRs were tested. The amplitude stability and the phase error of each CR were estimated. A precise tracking of two CRs installed at the glacier surface was also able to measure the displacement of the Argentière glacier, giving results close to previous GPS measurements. Furthermore, a Persistent Scatterer Interferometry (PSI) study was conducted, using the most stable CR as reference point to estimate slope instabilities, which led to the identification of an area corresponding to a tectonic fault called “Faille de l’angle”. The precise absolute locations of the CRs were successfully estimated and PS heights were compared with a LiDAR-based (Light Detection And Ranging) digital elevation model (DEM) and GPS measurements.