UBC Theses and Dissertations
Digital signal processing of UHF radio echo sounding data from northern Ellesmere Island Prager, Bradley Thomas
This thesis is a preliminary attempt to apply digital signal processing techniques to ice radar data. Seismic processing inspired many of the techniques: linear filtering, differentiating, automatic gain control, and stacking. The processing is designed to enhance the radar section by reducing noise and increasing the amplitude of small reflections, making reflections easier to locate. Once reflections have been located, ice thickness and reflector properties can be interpreted from the data. Ice thickness and power reflection coefficient (PRC) can always be obtained; if the depth to the reflector undergoes a sufficiently large change, the propagation loss rate of the ice can also be calculated. The processing and interpretation techniques are applied to ice radar data from a 1981 survey on northern Ellesmere Island. Ice thickness, PRC, and propagation loss rate for the following areas are calculated: Milne and Disraeli Glaciers, Milne and Ward Hunt Ice Shelves, and a small ice cap surrounding Mt. Oxford. The glaciers have a maximum thickness exceeding 700 m, a basal PRC of about -30 dB, and a typical propagation loss rate of 0.025 dB/m (at 840 MHz). The thinner ice areas of the Milne and Ward Hunt Ice Shelves produce either no basal reflection or only a faint reflection; this is taken to indicate basal accretion of brackish ice or brine soaking, produced by meltwater flowing out from the fiords underneath the ice shelves.
Item Citations and Data