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 to the bed in the ablation zone of GrIS. Unexpectedly, sliding completely dominates ice motion all winter, despite a hard bedrock sub- strate 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 bed- rock 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.
Read more: Maier, N., N. Humphrey, J. Harper and T. Meierbachtol, 2019. Sliding dominates slow-flowing margin regions, Greenland Ice Sheet. Sci. Adv. 5, DOI: 10.1126/sciadv.aaw5406