Grounding-zone flow variability of Priestley Glacier, Antarctica, in a
diurnal tidal regime
Dynamics of polar outlet glaciers vary with ocean tides, providing a
natural laboratory to understand basal processes and ice rheology. We
apply Terrestrial Radar Interferometry to close the spatiotemporal gap
between GNSS and satellite observations. Three-hour flowfields collected
over an eight day period at Priestley Glacier, Antarctica, validate and
provide the spatial context for concurrent GNSS measurements. Ice flow
is fastest during falling tides and slowest during rising tides.
Principal components of the timeseries prove upstream propagation of
tidal signatures $>$ 10 km away from the grounding line.
Hourly, cm-scale horizontal and vertical flexure patterns occur
$>$6 km upstream of the grounding line. Vertical uplift
upstream of the grounding line is consistent with ephemeral re-grounding
during low-tide impacting grounding-zone stability. Taken together,
these observations identify tidal imprints on ice-stream dynamics on new
temporal and spatial scales providing constraints for models designed to
isolate dominating processes in ice-stream mechanics.