Comparing satellite and helicopter-based methods for observing crevasses, application in East Antarctica

Knowing where crevasses are is critical for planning safe on-ice field operations. Previous methods have ranged from real-time imaging of subsurface structures using ground penetrating radar, to mapping of crevasses over large areas using satellite imagery, with each method having it's own strengths and weaknesses. In this paper we compare the detection of crevasses at the Totten Glacier, East Antarctica, from helicopter-borne ground penetrating radar with satellite-based microwave synthetic aperture radar imagery. Our results show that the 80 MHz helicopter-borne ground penetrating radar was able to detect crevasses up to a depth of 70 m, with snow bridge thickness of >30 m. Comparison with TerraSAR-X (X-band, 9.6 GHz) satellite imagery indicates that the latter is highly effective, detecting 100% of crevasses with snow bridges of up to 4 m thick and detected 95% of crevasses with snow bridges up to 10 m thick. The ability of both methods to identify individual crevasses is affected by several factors including crevasse geometry, survey or satellite orientation and snow moisture content, and further experiments are planned to investigate performance under a wider range of conditions.