Dielectric constant and layer-thickness interpretation of helicopter-borne short-pulse radar waveforms reflected from wet and dry river-ice sheets

The objective of the study described was to demonstrate that radar ice thickness profiling is possible under some wet conditions. Radar data for both wet and dry ice were extracted from surveys performed from a helicopter operating at an altitude of about 2-7 m and a speed of about 5 m/s. The radar used a broadband wavelet of several nanoseconds duration at a center frequency of about 500 MHz. By use of plane wave theory, individual waveforms within particular echo scans are analyzed to interpret a value for the solid-ice dielectric constant and thus ice thickness, the latter values of which correlate with some very limited observations. Given this dielectric constant, the theory is then used to reproduce the observed effects of the melt upon the radar reflections and this to predict the range of melt conditions over which ice thickness may still be interpreted