Improved ice velocity measurements with Sentinel-1 TOPS interferometry

In recent years, the Sentinel-1 satellites have provided a data archive of unprecedented volume, delivering C-band Synthetic Aperture Radar (SAR) acquisitions over most of the polar ice sheets with a repeat-pass period of 6-12 days using Interferometric Wide swath (IW) imagery acquired in Terrain Ob...

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Bibliographic Details
Published in:Remote Sensing
Main Authors: Andersen, Jonas Kvist, Kusk, Anders, Boncori, John Peter Merryman, Hvidberg, Christine Schøtt, Grinsted, Aslak
Format: Article in Journal/Newspaper
Language:English
Published: 2020
Subjects:
DInSAR
Greenland ice sheet
Ice velocity
Sentinel-1
TOPS
Greenland
The Sentinel
Ice Sheet
Online Access:https://orbit.dtu.dk/en/publications/05b0c748-9203-4b9c-b981-7f64d4e05fb4
https://doi.org/10.3390/rs12122014
https://backend.orbit.dtu.dk/ws/files/216406881/remotesensing_12_02014_v2.pdf
https://doi.org/10.11583/DTU.12865709.v1
Description
Summary:In recent years, the Sentinel-1 satellites have provided a data archive of unprecedented volume, delivering C-band Synthetic Aperture Radar (SAR) acquisitions over most of the polar ice sheets with a repeat-pass period of 6-12 days using Interferometric Wide swath (IW) imagery acquired in Terrain Observation by Progressive Scans (TOPS) mode. Due to the added complexity of TOPS-mode interferometric processing, however, Sentinel-1 ice velocity measurements currently rely exclusively on amplitude offset tracking, which generates measurements of substantially lower accuracy and spatial resolution than would be possible with Differential SAR Interferometry (DInSAR). The main difficulty associated with TOPS interferometry lies in the spatially variable azimuth phase contribution arising from along-track motion within the scene. We present a Sentinel-1 interferometric processing chain, which reduces the azimuth coupling to the line-of-sight phase signal through a spatially adaptive coregistration refinement incorporating azimuth velocity measurements. The latter are based on available ice velocity mosaics, optionally supplemented by Burst-Overlap Multi-Aperture Interferometry. The DInSAR processing chain is demonstrated for a large drainage basin in Northeast Greenland, encompassing the Northeast Greenland Ice Stream (NEGIS), and integrated with state-of-the-art offset tracking measurements. In the ice sheet interior, the combined DInSAR and offset tracking ice velocity product provides a spatial resolution of 50 x 50 m and 1-sigma accuracies of 0.18 and 0.44 m/y in the x and y components respectively, compared to GPS.

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