Campus Units

Geological and Atmospheric Sciences

Document Type

Article

Publication Version

Published Version

Publication Date

2-2015

Journal or Book Title

Journal of Glaciology

Volume

61

Issue

225

First Page

1

Last Page

7

DOI

10.3189/2015JoG14J174

Abstract

The contribution of glaciers to sea-level rise and their effects on landscape evolution depend on the poorly known relationship between sliding speed and drag at the ice/bed interface. Results from experiments with a new rotary laboratory device demonstrate empirically for the first time a double-valued drag relationship like that suggested by some sliding theories: steady drag on a rigid, sinusoidal bed increases, peaks and declines at progressively higher sliding speeds due to growth of cavities in the lee sides of bed undulations. Drag decreases with increased sliding speed if cavities extend beyond the inflection points of up-glacier facing surfaces, so that adverse bed slopes in contact with ice diminish with further cavity growth. These results indicate that shear tractions on glacier beds can potentially decrease due to increases in sliding speed driven by weather or climate variability, promoting even more rapid glacier motion by requiring greater strain rates to produce resistive stresses. Although a double-valued drag relationship has not yet been demonstrated for the complicated geometries of real glacier beds, both its potential major implications and the characteristically convex stoss surfaces of bumps on real glacier beds provide stimulus for exploring the effects of this relationship in ice-sheet models.

Comments

This article is from Journal of Glaciology 61 (2015): 1, doi:10.3189/2015JoG14J174. Posted with permission.

Rights

Creative Commons Attribution license.

Copyright Owner

International Glaciological Society

Language

en

File Format

application/pdf

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