Synthetic Aperture Radar TOPS-mode Interferometry for Ice Velocity Retrieval
Mass loss from the world’s ice sheets and glaciers is one of the largest contributors to ongoing sea level rise. For both the Greenland and Antarctic ice sheets, a significant part of the mass loss stems from changes in ice dynamics, with many marine-terminating outlet glaciers consistently accelera...
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| Format: | Book |
| Language: | English |
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Technical University of Denmark
2022
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| Online Access: | https://orbit.dtu.dk/en/publications/4b140e68-3d52-4a6c-a82a-9a6b80ab71d4 https://backend.orbit.dtu.dk/ws/files/304333122/Afhandling_Jonas_Kvist_Andersen.pdf |
| Summary: | Mass loss from the world’s ice sheets and glaciers is one of the largest contributors to ongoing sea level rise. For both the Greenland and Antarctic ice sheets, a significant part of the mass loss stems from changes in ice dynamics, with many marine-terminating outlet glaciers consistently accelerating and retreating. Ice velocity is an essential variable in monitoring the state of ice sheets and glaciers. Over the past several decades, a revolution in the quality and availability of Synthetic Aperture Radar (SAR) satellite data has allowed frequent ice velocity retrievals to be carried out over major parts of the ice sheets. Particularly, the EU/ESA Sentinel-1 SAR satellites have been widely utilized in the generation of seasonal, annual, and multi-annual velocity retrievals, owing to their extensive coverage, facilitated by the Terrain Observation by Progressive Scans (TOPS) acquisition mode. So far, however, routine Sentinel-1 ice velocity measurements have relied solely on amplitude-based methods, which produce measurements of significantly lower accuracy and resolution than phase-based Differential SAR Interferometry (DInSAR). The main reason for this discrepancy is the added complexity introduced to interferometric processing by the TOPS acquisition mode, where along-track motion is coupled to the interferometric phase. In this thesis, a refined image coregistration approach is developed, which alleviates the TOPS-related challenges and allows interferometric ice velocity retrieval from the extensive Sentinel-1 polar archive. A demonstration is provided of a combined DInSAR and amplitude offset tracking 2D velocity retrieval, which exploits the high accuracy and resolution of DInSAR in slower-moving inland regions and the ability of offset tracking to retrieve measurements from fast-flowing glacier outlets, highlighting the synergy between the two techniques. In the context of ice velocity retrieval, particularly in downstream regions, phase unwrapping errors is the most prominent error source in DInSAR ... |
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