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Abstract:
Satellite based synthetic aperture radar (SAR) interferometry (InSAR) has become a widely used tool for mapping and monitoring surface displacements alongside GNSS. The launch of the Sentinel-1 satellites, providing high-quality SAR images in C-band (5.405 GHz) at a very high temporal frequency (every 6 days until the end of 2021). The advancements both in computing capacity and processing algorithms enabled the determination of surface displacements on regional and even continental scale. C-band based InSAR processing has many limitations however, when applied in temperate regions. Seasonal change in soil moisture, vegetation foliage, surface coverage (snow cover) and agricultural activities (plowing, seeding, crop development) can all lead to loss of coherence and consequently loss of deformation information. These factors can render the determination of surface motions very difficult in areas where the velocity of these motions is low (< 1-2 mm / year). In this contribution the authors wish to present results of InSAR processing applied to an area (Hungary in Central Europe) where the mentioned limitations (temperate region, low expected displacement velocities) are present. Approximately 250 Sentinel-1 images, both ascending and descending direction, between 2016 and 2021 were processed covering the area of interest. The images were processed using the Gamma software package (https://www.gamma-rs.ch/software) with both Persistent Scatterer (PS) and Small Baseline (SBAS) InSAR processing methods. We present the results of the two processing strategies, discuss the advantages and shortcomings, and provide an outlook on future work, with recommendations on how to plan and execute such large-scale analysis.
