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Present Dynamics and Future Prognosis of a Slowly Surging Glacier : Volume 4, Issue 4 (01/10/2010)

By Flowers, G. E.

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Book Id: WPLBN0003990153
Format Type: PDF Article :
File Size: Pages 38
Reproduction Date: 2015

Title: Present Dynamics and Future Prognosis of a Slowly Surging Glacier : Volume 4, Issue 4 (01/10/2010)  
Author: Flowers, G. E.
Volume: Vol. 4, Issue 4
Language: English
Subject: Science, Cryosphere, Discussions
Collections: Periodicals: Journal and Magazine Collection (Contemporary), Copernicus GmbH
Historic
Publication Date:
2010
Publisher: Copernicus Gmbh, Göttingen, Germany
Member Page: Copernicus Publications

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Pimentel, S., Roux, N., & Flowers, G. E. (2010). Present Dynamics and Future Prognosis of a Slowly Surging Glacier : Volume 4, Issue 4 (01/10/2010). Retrieved from http://nook-library.net/


Description
Description: Department of Earth Sciences, Simon Fraser University, Burnaby, BC, Canada. Glacier surges are a well-known example of an internal dynamic oscillation whose occurrence is not a direct response to the external climate forcing, but whose character (e.g. period, mechanism) may depend on the glacier's environmental or climate setting. We examine the dynamics of a small (~5 km2) valley glacier in the Yukon Territory of Canada, where two previous surges have been photographically documented and an unusually slow surge is currently underway. To characterize the dynamics of the present surge, and to speculate on the future of this glacier, we employ a higher-order flowband model of ice dynamics with a Coulomb-friction sliding law in both diagnostic and prognostic simulations. Diagnostic (force balance) calculations capture the measured ice-surface velocity profile only when high basal water pressures (55–90% of flotation) are prescribed over the central region of the glacier, consistent with where evidence of the surge has been identified. This leads to sliding accounting for 50–100% of the total surface motion. Prognostic simulations, where the glacier geometry evolves in response to a prescribed surface mass balance, reveal a significant role played by a large bedrock bump beneath the current equilibrium line of the glacier. This bump provides resistance to ice flow sufficient to cause the formation of a bulge in the ice-surface profile. We suggest that the bedrock bump contributes to the propensity for surges in this glacier, such that conditions suppressing ice-bulge formation over the bump may also inhibit surges. In our calculations such a situation arises for sufficiently negative values of mass balance. Collectively, these results corroborate our interpretation of the current glacier flow regime as indicative of a slow surge, and confirm a relationship between surge incidence or character and the net mass balance. Our results also highlight the importance of glacier bed topography in controlling ice dynamics, as observed in many other glacier systems.

Summary
Present dynamics and future prognosis of a slowly surging glacier

Excerpt
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