Persistence and variability of ice-stream grounding lines on retrograde bed slopes
In many ice streams, basal resistance varies in space and time due to the dynamically evolving properties of subglacial till. These variations can cause internally generated oscillations in ice-stream flow. However, the potential for such variations in basal properties is not considered by conventio...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-08-01
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| Series: | The Cryosphere |
| Online Access: | http://www.the-cryosphere.net/10/1883/2016/tc-10-1883-2016.pdf |
| Summary: | In many ice streams, basal resistance varies in space and time due to the
dynamically evolving properties of subglacial till. These variations can
cause internally generated oscillations in ice-stream flow. However, the
potential for such variations in basal properties is not considered by
conventional theories of grounding-line stability on retrograde bed slopes,
which assume that bed properties are static in time. Using a flow-line model,
we show how internally generated, transient variations in ice-stream state
interact with retrograde bed slopes. In contrast to predictions from the
theory of the marine ice-sheet instability, our simulated grounding line is
able to persist and reverse direction of migration on a retrograde bed when
undergoing oscillations in the grounding-line position. In turn, the presence
of a retrograde bed may also suppress or reduce the amplitude of internal
oscillations in ice-stream state. We explore the physical mechanisms
responsible for these behaviors and discuss the implications for observed
grounding-line migration in West Antarctica. |
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| ISSN: | 1994-0416 1994-0424 |