ABSTRACT: Flow dynamics of the Kaskawulsh Glacier, Yukon.

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Abstract

The Kaskawulsh Glacier comprises one of the largest glaciers in the Yukon, with a length of ~70 km and ice depths of >500 m. Here we describe the use of continuous differential GPS (dGPS) measurements (made since 2008) and speckle tracking of Radarsat-2 scenes (acquired in 2010-11) to present the first complete velocity maps for the glacier. These measurements show average velocities across the ablation area of ~160 m/yr, but with strong seasonal variability. Annual minimum velocities are reached in the late fall (typically November), with a small, but gradual increase through the winter (January to March), even though there is little to no surface melt during this time. Velocities increase rapidly at the glacier terminus in mid-May as the summer melt season starts, and then progress upglacier over the next several weeks. The rate of velocity increase is greatest near the terminus at this time (more than double winter values), with the rate of increase becoming dampened with distance upglacier towards the equilibrium line. This period of enhanced horizontal motion lasts for over a month, and is typically associated with significant vertical uplift (up to ~0.5 m). Our observations suggest that increases in surface motion in the winter are driven by a reorganization (closing) of the subglacial drainage system and associated increase in basal water pressure. In contrast, sudden melt inputs drive the velocity events at the start of the summer.

Bibliography of Canadian Geomorphology