Timescales of outlet-glacier flow with negligible basal friction: Theory, observations and modeling ...

• Main Authors: Feldmann, Johannes, Levermann, Anders
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Katlenburg-Lindau : Copernicus 2023
• Subjects: flow field; friction; glacier flow; ice flow; observational method; sea level change; timescale; Antarctica; 910; Antarc*
• Online Access: https://dx.doi.org/10.34657/11319; https://oa.tib.eu/renate/handle/123456789/12287

The timescales of the flow and retreat of Greenland's and Antarctica's outlet glaciers and their potential instabilities are arguably the largest uncertainty in future sea-level projections. Here we derive a scaling relation that allows the comparison of the timescales of observed complex ice flow fields with geometric similarity. The scaling relation is derived under the assumption of fast, laterally confined, geometrically similar outlet-glacier flow over a slippery bed, i.e., with negligible basal friction. According to the relation, the time scaling of the outlet flow is determined by the product of the inverse of (1) the fourth power of the width-To-length ratio of its confinement, (2) the third power of the confinement depth and (3) the temperature-dependent ice softness. For the outflow at the grounding line of streams with negligible basal friction, this means that the volume flux is proportional to the ice softness and the bed depth, but goes with the fourth power of the gradient of the bed and with ...