Observations of sub-monthly melt rate variability at the Filchner-Ronne Ice Shelf

Irena Vankova, Los Alamos National Laboratory, Los Alamos, United States and Keith W Nicholls, British Antarctic Survey, Cambridge, United Kingdom
Autonomous phase-sensitive radio-echo sounders (ApRES) were deployed at several locations spread across the Filchner-Ronne Ice Shelf to measure basal motion and internal vertical ice motion at 2-hourly resolution.
Separation of vertical strain changes from the total thickness changes using techniques appropriate for each time scale of interest yielded basal melt estimates.
Evidence of semi-diurnal tidal melt variability was observed at approximately half of the sites. Comparison with longterm mean melt show that one of the observed sites experiences refreezing at some point of the tidal cycle.
Melt rate variability at weekly timescales is also location dependent: at some sites it is absent, elsewhere it dominates the signal.
Using one particularly dynamic site as an example, we illustrate how observations collected from an ice shelf surface can be used to get an insight into oceanic physical processes beneath the ice shelf.