Airborne UHF radar sounding of glaciers and ice shelves, northern Ellesmere Island, Arctic Canada

Abstract

More than 2000 line-kilometres of ice were sounded in 1981 using an 840 MHz pulsed radar system. The surveyed regions include Mt. Oxford ice cap, Disraeli Glacier, Milne Glacier, Ward Hunt Ice Shelf, and Milne Ice Shelf in northern Ellesmere Island, Arctic Canada. The maximum ice thickness that was reliably recorded was 750 m for Milne Glacier. In addition to ice thickness interpretation, the power reflection coefficient (PRC) and propagation loss rate were estimated from the data. Measured basal PRC's differ for ice shelves, floating glaciers, and grounded glaciers. Spatial variations of PRC have been used to infer a composite structure for the ice shelves. Ward Hunt Ice Shelf proved difficult to sound, probably because of its known saline and brackish chemistry. Excellent results were obtained for Milne Ice Shelf and its depth was found to average roughly 70 m, in places attaining 100 m. Bottom-side crevasses were observed within Milne Ice Shelf. The characteristic ridge and trough topography of the ice shelf surface has little or no bottom-side expression.