Seasonal patterns of Greenland ice velocity from Sentinel-1 SAR data linked to runoff

Accurate projections of the mass loss from the Greenland Ice Sheet (GrIS) require a complete understanding of the ice-dynamic response to climate forcings on seasonal and interannual timescales and would greatly benefit from more observational evidence. Here, we analyze a 5-year, high-resolution data set of ice velocities of the GrIS using K-means, an unsupervised clustering algorithm, to identify ice-sheet wide characteristic seasonal flow patterns. We include all areas flowing >0.3 m/d and obtain an ice-sheet wide overview of the seasonality and the interannual variability. It shows both a spatial and interannual variability in seasonal flow patterns, both along individual glaciers and between glaciers. We compare with runoff from a regional climate model and infer that the ice-sheet wide patterns are linked to the availability of water penetrating to the base of the ice.