Grounding-zone flow variability of Priestley Glacier, Antarctica, in a diurnal tidal regime
Tidal modulation of ice streams and their adjacent ice shelves is a real-world experiment to understand ice-dynamic processes. We observe the dynamics of Priestley Glacier, Antarctica, using Terrestrial Radar Interferometry (TRI) and GNSS. Ocean tides are predominantly diurnal but horizontal
GNSS displacements also oscillate semi-diurnally. The oscillations are strongest in the ice shelf and tidal
signatures decay near-linearly in the TRI data over >10 km upstream of the grounding line. Tidal flexing is observed >6 km upstream of the grounding line including cm-scale uplift. Tidal grounding line migration is small and <40% of the ice thickness. The frequency doubling of horizontal displacements relative to the ocean tides is consistent with variable ice-shelf buttressing demonstrated with a visco-elastic Maxwell model. Taken together, this supports previously hypothesized flexural ice softening in the grounding-zone through tides and offers new observational constraints for the role of ice rheology in ice-shelf buttressing.
Authors: Drews, Reinhard, Wild, Christian T, Marsh, Oliver J. ORCID record for Oliver J. Marsh, Rack, Wolfgang, Ehlers, Todd A., Neckel, Nikals, Helm, Veit