Sliding dominates slow-flowing margin regions, Greenland Ice Sheet
On the Greenland Ice Sheet (GrIS), ice flow due to deformation and sliding across the bed delivers ice to lower-elevation marginal regions where it can melt. We measured the two mechanisms of motion using a three-dimensional array of 212 tilt sensors installed within a network of boreholes drilled t...
| Published in: | Science Advances |
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| Main Authors: | , , , |
| Format: | Text |
| Language: | English |
| Published: |
American Association for the Advancement of Science
2019
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| Subjects: | |
| Online Access: | http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6620096/ http://www.ncbi.nlm.nih.gov/pubmed/31309154 https://doi.org/10.1126/sciadv.aaw5406 |
| Summary: | On the Greenland Ice Sheet (GrIS), ice flow due to deformation and sliding across the bed delivers ice to lower-elevation marginal regions where it can melt. We measured the two mechanisms of motion using a three-dimensional array of 212 tilt sensors installed within a network of boreholes drilled to the bed in the ablation zone of GrIS. Unexpectedly, sliding completely dominates ice motion all winter, despite a hard bedrock substrate and no concurrent surface meltwater forcing. Modeling constrained by detailed tilt observations made along the basal interface suggests that the high sliding is due to a slippery bed, where sparsely spaced bedrock bumps provide the limited resistance to sliding. The conditions at the site are characterized as typical of ice sheet margins; thus, most ice flow near the margins of GrIS is mainly from sliding, and marginal ice fluxes are near their theoretical maximum for observed surface speeds. |
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