Glaciological Applications of Terrestrial Radar Interferometry

Terrestrial Radar Interferometry (TRI) is a relatively new ground-based technique that combines the precision and spatial resolution of satellite interferometry with the temporal resolution of GPS. Although TRI has been applied to a variety of fields including bridge and landslide monitoring, it is ideal for studies of the highly-dynamic terminal zones of marine-terminating glaciers, some of which are known to have variable velocities related to calving and/or ocean-forced melting. My TRI instrument is the Gamma Portable Radar Interferometer, which operates at 17.2 GHz (1.74 cm wavelength), has two receiving antennas for DEM (digital elevation model) generation, and images the scenes at minute-scale sampling rates. Most of this TRI work has focused on two glaciers: Breiðamerkurjökull in Iceland and Helheim in Greenland. Monitoring the displacement of stationary points suggests velocity measurement uncertainties related to the instrument and atmosphere of less than 0.05 m/d. I show that the rapid sampling rate of the TRI can be used to observe velocity variations at the glacier terminus and assess the impact and spatial distribution of tidal forcing. Additionally, iceberg tracking in the amplitude imagery may provide insight about ocean currents near the terminus