Synergistic fusion of interferometric and speckle-tracking methods for deriving surface velocity from interferometric SAR data

This letter presents a technique to adjust and unify disconnected interferogram fringe regions for the derivation of accurate surface-velocity measurements. The interferogram from repeat-pass interferometric synthetic aperture radar data is often partitioned by shear margins of ice streams and other low-coherence zones into many small disconnected fringe regions. Although these isolated fringe regions can be unwrapped separately, the unwrapped phase for each region is referenced to a different seed point. Our technique exploits absolute range-offset measurements from the speckle-tracking method to bridge the isolated fringe regions in the interferogram. In this way, the unwrapped phases in these regions can be adjusted into consistent surface-displacement measurements with a common reference point. Using Radarsat interferometric data in Antarctica, we demonstrated that the synergetic fusion of the measurements from the interferometric and speckle-tracking methods can produce a highly accurate two-dimensional velocity field.