The Role of Basal Control on the Flow of the Rutford Ice Stream, West Antarctica: an Inverse Modeling Approach

 

This project aims at determining basal topography and basal slipperiness beneath ice streams through inverse modeling of surface data. The inverse model will be applied to a flow line of the Rutford Ice Stream, West Antarctica. An area within this ice stream where a clear topographic expression of a basal undulation is visible has been selected for this purpose. Field measurements will be conducted in 2002/2003 by the British Antarctic Survey (BAS).

Our main objectives are: 1) Forward calculation of the finite-amplitude transfer of variations in basal topography to the glacier surface using a non-linear finite-element model. 2) Non-linear inverse modeling of surface data with an inverse step based on an analytical small-amplitude perturbation model and a forward step using a non-linear finite-element model.

Both the non-linear finite-element model and the linear analytical model will take transmission of horizontal stress gradients into account while also accounting for variations in ice deformation with depth. The spatial resolution of this inversion model will be on one ice-thickness scale, which is higher than previously possible. The joint non-linear inversion for basal topography and basal slipperiness has not been done before. This project will open up a new window on the nature of basal control on ice streams.