Persistence and Variability of Ice Stream Grounding Lines on Retrograde Bed Slopes
Robel, Alexander A.
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CitationRobel, Alexander A., Christian Schoof, and Eli Tziperman. 2016. “Persistence and Variability of Ice-Stream Grounding Lines on Retrograde Bed Slopes.” The Cryosphere 10 (4): 1883–96. https://doi.org/10.5194/tc-10-1883-2016.
AbstractIn 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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