RT Journal Article
SR Electronic
T1 Sliding dominates slow-flowing margin regions, Greenland Ice Sheet
JF Science Advances
JO Sci Adv
FD American Association for the Advancement of Science
SP eaaw5406
DO 10.1126/sciadv.aaw5406
VO 5
IS 7
A1 Maier, Nathan
A1 Humphrey, Neil
A1 Harper, Joel
A1 Meierbachtol, Toby
YR 2019
UL http://advances.sciencemag.org/content/5/7/eaaw5406.abstract
AB 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.