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| Titel |
Drag on a sphere in moving temperate ice |
| VerfasserIn |
D. Cohen, N. R. Iverson, J. Byers |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250021319
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| Zusammenfassung |
| Glacier dynamics, sediment transport, and erosion are controlled in part by forces at the
interface between basal ice and bedrock. One such force is the drag ice exerts on the bed as it
slides past bedrock obstacles. Another is the contact force between a clast and the bedrock.
These forces affect many processes, such as basal friction that regulates sliding speed, slip
resistance and associated seismic stick-slip, and abrasion that controls rates of erosion,
landscape evolution, and production of sediment. Direct field or laboratory measurements of
these forces are lacking. Here we report laboratory measurements of the drag force on a
sphere in ice (physically analogous to ice sliding past a hemispheric obstacle) and describe
future experiments in which the contact force between the same sphere and a flat bed will be
measured.
A single apparatus was designed to measure drag in the two experiments. The apparatus
consists of a cylindrical polycarbonate vessel, 24 cm high and 20 cm in diameter, containing
ice at the melting temperature. A hydraulic press keeps the pressure in the ice at
1.0–1.5 MPa. Ice temperature is controlled by circulating a fluid at a precise temperature in
channels inside the polycarbonate vessel and in its lid. Ice moves downward inside the
polycarbonate chamber by melting at its base. The melt rate is controlled by circulating
another fluid through the bed. The temperatures of both fluids are controlled to within |
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