资源环境科技发展态势分析平台

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 oscillate also 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.