Abstract
The objective of this work is to exploit multi-source and multifrequency Synthetic Aperture Radar (SAR) images to estimate the permafrost deformation in correspondence of the alpine active rock glacier of Lazaun located in the in Schnalstal Alps (Italy). The rock glacier is 660 m long and 200 m wide, the gradient of the front goes from 35° to 45°, and previous studies using GPS techniques reported that flow velocities reach 4.5mm/day at the front of the rock glacier. TerraSAR-X, CSK, CSG, Sentinel-1 and SAOCOM SAR data were collected and tested over the period 2016 to 2022. At this aim, the Intensity tracking approach was selected and adapted to the case study to estimate seasonal and interannual displacement while DInSAR was used for shorter temporal resolution. The analysis presents challenges in terms of topography, limited duration of the snow-free season, deformation rate and the limited size of the area itself. The above-mentioned methods are based on different principles and are complementary: very high spatial resolution and moderate temporal resolution work best for intensity tracking, while a high temporal resolution is required for DInSAR. For the case of Intensity tracking, referring to GPS measurements available, the best results allowed to reach a RMSE of about 0.34mm/day with a Pearson correlation coefficient of ca. 0.89 in both azimuth and range direction.
This work was carried out in the framework of the project “CRIOSAR: Applicazioni SAR multifrequenza alla criosfera”, funded by ASI under grant agreement n. ASI N. 2021-12-U.0. TerraSAR-X data were provided by the European Space Agency, Project Proposal id 34722, © DLR, distribution Airbus DS Geo GmbH, all rights reserved.