Coherence Tracking and its Adaptation to TOPSAR Acquisition Mode - Study case over Antarctic Ice Shelves

• Main Authors: Glaude, Quentin, De Rauw, Dominique, Barbier, Christian, Pattyn, Frank
• Format: Conference Object
• Language: English
• Published: 2021
• Subjects: Physical; chemical; mathematical & earth Sciences; Earth sciences & physical geography; Physique; chimie; mathématiques & sciences de la terre; Sciences de la terre & géographie physique; Antarc*; Antarctic; Antarctica; Ice Shelves
• Online Access: https://orbi.uliege.be/handle/2268/267388; https://orbi.uliege.be/bitstream/2268/267388/1/Quentin%20Glaude%20Coherence%20Tracking.pdf

Synthetic Aperture Radar (SAR) Remote Sensing already proved as an ideal solution to determine surface displacements, thanks to its day-and-night and cloud-free characteristics. Furthermore, more and more acquisitions are becoming available for users (Radarsat Constellation Mission, Cosmo Skymed, SAOCOM, Sentinel-1, and so forth). To detect displacements, SAR has several techniques. Using SAR images at different times from slightly different points of view, we can observe surface movements by phase shift measurements between acquisitions. These techniques belong to the branch of differential interferometry (DInSAR, SBAS, MSBAS, PSI, MAI, BOI, and so forth). DInSAR can determine displacements according to the line of sight of the sensor with an accuracy that can go below the centimeter, with a sensor at several hundreds of kilometers distance. This partly explained the success of DInSAR. Then, to reconstruct the bi- or tri-dimensional displacements, we need other measures from other orbits. Combining a great number of images from several orbits, we can reconstruct the full vectorial components of the surface movement. Unfortunately, this abundance of orbits is far from achievable everywhere on Earth. In particular, Antarctica has many geographical areas where only a limited number of orbits is available. Besides, techniques based on SAR interferometry are limited by other factors. Among them, the magnitude of the displacements can introduce a decorrelation such that the wavefronts combination emitted from two different times does not give a coherent signal. This temporal decorrelation is particularly remarkable in coastal regions of Antarctica, where the revisit time of Sentinel-1 (6 or 12 days, depending on the region) allows the scatterers to move from one picture element to another. In these cases, it is possible to employ another family of techniques, based on the tracking of feature elements at the surface. In SAR remote sensing, we talk of speckle tracking. In speckle tracking, the technique uses two SAR ...