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InSAR-derived horizontal velocities in a global reference frame
  • Milan Lazecky,
  • Andrew Hooper
Milan Lazecky
University of Leeds

Corresponding Author:m.lazecky@leeds.ac.uk

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Andrew Hooper
University of Leeds, COMET
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Interferometric Synthetic Aperture Radar (InSAR) is used to measure deformation rates over whole continents to constrain tectonic processes. The resulting velocity measurements are only relative, due to unknown integer ambiguities introduced during propagation of the signal through the atmosphere. However, these ambiguities mostly cancel when using spectral diversity to estimate along-track motion, allowing measurements to be made with respect to a global reference frame. Here, we calculate along-track velocities for a partial global dataset of Sentinel-1 acquisitions and find good agreement with ITRF2014 model values. We include corrections for solid-earth tides and gradients of ionospheric total electron content. By combining data from ascending and descending orbits we are able to estimate north and east velocities with average precision of 4 and 20 mm/year, respectively. Although we have calculated these over large 250x250 km areas, such measurements can also be made at much higher resolution, albeit with lower accuracy. These “absolute” measurements can be particularly useful for global velocity and strain rate estimation, where GNSS measurements are sparse.