Rheology of Basal Ice

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This work is to study glacier dynamics and hydrology of a glacier in Sweden. The glacier drainage system, the subglacial till and its velocity close to the bottom, will be examined. The data obtained will be used, in conjunction with a finite element model of the flow, to study the rheology of this glacier. An instrument panel beneath the glacier Engabreen in Norway has been installed, which contains a conical bump, 0.15 m high. The bed of the glacier is accessed through tunnels in the rock, excavated for hydroelectric purposes. The ice is about 200 m thick at the site of the panel. The measurements made include the temperature distribution in the bump, the pressure on either side of the bump, the total bed-parallel force, and the sliding speed. The sliding speed is measured by monitoring the movement of ice past windows with the use of video cameras. The investigators plan to melt out the layer of dirty ice at the base of the glacier and thereby bring clean ice in contact with the instrumented panel. Thus, markers emplaced in the ice above the bed will be visible by the video cameras, and the ice velocity distribution will be determined. In addition, the PIs will measure the water content of the basal clean ice, and take cores for fabric analysis.