Satellite Interferometry

One aspect of ice-sheet modelling that is in need of independent datasets for comparison and validation is the calculated velocity of ice. Until recently, such data have been scarce over large ice sheets. However, recent interferometric Synthetic Aperture Radar (SAR) InSAR techniques have been applied to glaciers and ice sheets to reveal the surface velocity continuously across wide areas. Work to date has shown that development of ice streams in West Antarctica seen through InSAR data (Joughin et al., 1999) compares well with calculations of Antarctic ice flux (Bamber et al., 2000). Maps of surface ice velocities are currently being assembled for the whole of Antarctica, which may be a vital dataset for model verification in future.

InSAR data revealing the surface velocity of ice sheets also have an application in modelling subglacial sliding. In areas where the internal icesheet deformation is known to occur in a simple manner, the difference between the InSAR velocity and velocity due to internal deformation of ice will be equivalent to the component due to basal processes. Currently, models are incapable of accurately predicting subglacial sliding and, so, InSAR data may be of future use in establishing reliable algorithms for this process.

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