Our study of aufeis allowed us to investigate the potential of many different aspects of the new technology. Detecting change with interferometry is a matter of comparison, a technique measuring phase difference between orbits. For science, we need two acquisitions from the same area, either taken from two antennas simultaneously, or by one antenna on subsequent satellite passes. We used images acquired three days apart to work with pairs of single-look complex images. The team constructed a time series of 12 interferograms, each containing three maps, including backscatter change, phase difference and coherence maps.
Phase difference is a pixel by pixel depiction of difference between two compared images.
Coherence measures the degree to which the other two components change in a spatially random fashion. The 80-day high resolution aufeis mapping generated by the research team compares favorably with previous studies. T he ability of SAR to reveal surface change across large, and largely inaccessible areas is also key to a new technique that derives sea ice thickness in winter. Until now, sea ice thickness measurements have been limited to analysis of data from submarine sonars or moored, upward-looking sonars. Knowing sea ice thickness is important to climatologists since thickness affects the compressive strength of the ice and its rate of growth.