Abstract

The ice streams of Antarctica are fast flowing glaciers that move large amount of ice from the interior of the ice sheet towards the ocean. Despite being grounded, and therefore not directly subjected to oceanic tides, ice-stream flow is sometimes tidally modulated. These ice-stream tides are caused by oceanic tides, but the relationship between oceanic and ice-streams tides can be complex. As an example, on Rutford Ice Stream (RIS), one of the large ice streams of West Antarctica, ice flow speeds increase by 10 % in the course of about one week, and then decreases again in the following week. Despite being subjected to strong diurnal tides, there is little or no diurnal modulation in the flow of RIS . Response of ice streams to tides is critically affected by the mechanical conditions at the base of the ice stream. Observations and modelling of ice-stream tides can therefore be used establish constrains on basal processes and to test theoretical concepts about the flow of large ice masses.