Investigating the Flow Dynamics of Ice Shelves using Laboratory Experiments, Simple Theoretical Models and Geophysical Data Analysis

Abstract:

Ice-shelf calving-rates and the buttressing ice shelves provide to grounded ice are both difficult to model and quantify. An increased understanding of the mechanics of this process is imperative in determining the dynamics of marine ice sheets and consequently predicting their future extent and thickness.

Alley et al. (2008) proposed an empirically derived calving law, relating the calving rate to the strain rate at the calving front. However, Hindmarsh (2012) showed that a similar relationship could be deduced by considering the viscous flow of the ice shelf. We investigate the relationship between the ice shelf flow field and the strain rate field in the area close to the calving front. Analysis is undertaken of ice surface velocity data for a range of large Antarctic ice shelves (data from Rignot et al., 2011) and an inferred strain rate field produced from that data. These geophysical results are compared with a series of simple mathematical models from which thickness profiles and velocity fields can be obtained for a range of geometries and flow regimes.

Fluid mechanical laboratory experiments simulating the flow of an ice shelf in an idealized channel geometry provide a further comparison to the theoretical models and geophysical data, and allow a wider range of parameters to be tested. We show some results from these laboratory experiments aimed at exploring the success of the mathematical models.