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Examining the relationships between basal channels and ice shelf structural evolution with repeat, high-resolution elevation models and altimetry
  • Allison Chartrand,
  • Ian Howat
Allison Chartrand
Byrd Polar and Climate Research Center, The Ohio State University

Corresponding Author:allisonchartrand@gmail.com

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Ian Howat
Ohio State University
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Ice shelves control the stability of ice sheets and regulate ice sheet contribution to sea level rise by buttressing ice �ow. Most of Greenland’s ice shelves have already been lost, and many ice shelves around Antarctica are thinning and retreating. Ice shelves are increasingly vulnerable to thinning and destabilization due to surface and basal melting, and these processes may be exacerbated by the presence of basal channels, which are deep grooves that entrain meltwater at the base of ice shelves. Basal channels have been observed alongside spatial and temporal changes in grounding line geometry, strain rates and stress transfer, and the incidence and advection of other surface and basal features. The relationships between these processes, and their implications for ice shelf stability, remain largely unknown due to the lack of observations of su�ciently high spatial and temporal resolution. Our methodology employs high temporal and spatial resolution digital elevation models (DEMs) from REMA and ArcticDEM, laser altimetry from ICESat-2, radar sounding and laser altimetry from Operation IceBridge, and velocity data derived from interferometry, enabling us to constrain the morphology and evolution of channels and other ice shelf features at the fringes of both ice sheets. We intend to investigate how the relationships between channels, grounding line processes, and rifts and crevasses impact the persistence of ice shelf area necessary to maintain a “safety band”, or su�cient buttressing force, against grounded ice. Where time-evolving grounding line position data are sparse, we use the DEMs to track the boundary of hydrostatic equilibrium, which we use as a proxy for changes in grounding line position in order to investigate changes in ice shelf geometry. We have completed analysis of three ice shelves and plan to observe at least twelve more in order to develop an inventory of at- risk ice shelves. Based on our preliminary results, we hypothesize that rapidly evolving basal channels are associated with high rates of change in the grounding zone. This work is integral to assessing past and future ice shelf stability, and it will help the glacier dynamics community more accurately account for small-scale ice shelf processes in computational models which predict ice sheet contribution to sea level rise.