Scaling of Ice Stream Spacing and Flux from Numerical Simulations

Ice streams dominate the discharge of contemporary ice sheets, and are points of vulnerability for ice sheet instabilities. Therefore, to understand past and future ice sheet change we need to understand ice stream behaviour. Computer simulations can replicate the spacing and flux of palaeo and contemporary ice streams, but for accurate future projections we need confidence that simulated ice streams will evolve realistically. To explore controls on the spacing and flux of ice streams, we run simulations of a circular ice sheet on a flat bed. We simulate a series of idealised circular ice sheets of various radii, finding that simulated ice stream spacing and flux broadly resembles observations even on a flat bed, with total ice stream flux and frequency scaling with ice volume. We apply the model to the bed of an idealised Icelandic Ice Sheet, resulting in a greater streaming flux relative to the circular case. The realistic setting makes ice stream position insensitive to changes in geothermal heat flux, and the ice stream configuration alters when adjusting the topographic setting. These simulations demonstrate the sensitivity of ice stream behaviour to ice sheet size, with implications for how we simulate ice sheet change over medium and long timescales.