The response of Antarctic ice streams to tidal forcing

The transport of ice from the interior of Antarctica to the oceans is dominated by the flux through several fast-flowing ice streams whose behaviour is greatly influenced by the conditions at their base and at grounding points along the ice-ocean interface. The response of the ice velocity to changing basal conditions presents a key challenge for predicting future behaviour in a changing climate. Recent observations have shown that the motion of ice streams is sensitive, over 10s of kilometres, to ocean tides (Gudmundsson 2006, Minchew et al. 2017) suggesting a coupling between the flow of glacial ice, shear heating at lateral margins, and pore pressure changes in subglacial sediment. This project aims to understand the nonlinear coupling of viscous ice with the pressure-dependent rheology of the subglacial till through the use of highly resolved measurements of glacial motion, both spatially and temporally, in response to the tidal forcing.

This project combines analysis of satellite and GPS observations of the variability of ice stream motion in response to tidal forcing at a number of key Antarctic sites, along with simplified models of the motion of glacial ice over a poro-elastic subglacial till (Hewitt et al, in press). This combination of simple physical models and state-of-the-art observations combines two rapidly evolving scientific fields, poromechanics and remote sensing, to address fundamental questions in ice sheet evolution related to the mechanics of fluid-saturated subglacial sediments.