Form and flow of the Devon Island Ice Cap, Canadian Arctic

In this study, 3370 km of 100 MHz ice-penetrating radar data were acquired from Devon Ice Cap, Arctic Canada. Bed returns were obtained from >90% of flight tracks. Mean crossing point errors in ice surface elevation and ice thickness were 7-8 m. Digital elevation models of ice cap surface and bed elevation, and ice thickness, were produced and can be used as boundary conditions in numerical modeling. Devon Ice Cap, including 1960 km(2) of contiguous stagnant ice to its west, is 14,010 km(2). The ice cap proper is 12,050 km(2). Its largest drainage basin is 2630 km(2). The ice cap crest has a maximum measured elevation of 1921 m. Maximum recorded ice thickness is 880 m. Ice cap volume is 3980 km 3 (about 10 mm sea level equivalent). The bed, 8% of which lies below sea level, is an upland plateau dissected by steep- sided valleys that control the locations of the major outlet glaciers which dominate ice cap drainage. About 73 km, 4%, of the ice cap margin ends in tidewater. The margin is not floating. Icebergs of <100 m were observed offshore. Only a single outlet glacier showed signs of past surge activity. All major outlet glaciers along the eastern ice cap margin have retreated 1-3 km since 1960. Synthetic aperture radar-interferometic velocity structure shows slow, undifferentiated flow predominating in the west and center, with fast-flowing outlet glaciers and intervening slow-flowing ridges typical elsewhere. Outlet glacier velocities are 7-10 times higher than in areas of undifferentiated flow. This velocity structure, of fast-flowing units within slower-flowing ice, appears typical of many large (10(3) km(2)) Arctic ice caps.