Numerical Models of Ice-Shelf Flow: Ideal/Real
We present model calculations that describe the flow of ice shelves of different configurations. We consider “ideal” models with well-defined boundary conditions and simple geometry in order to explore the response of an ice shelf to transient variations in ice-stream input. Gradually increasing the complexity of these simple models allows a better understanding of ice-shelf behavior without the complications that would arise in considering natural ice shelves. We find that the dissipation of ice-thickness variations caused by ice-stream transience is strongly influenced by ice rheology. The presence of an ice rise significantly alters the velocity field of the adjacent ice, when changes in ice-stream input occur. With models of “real” ice shelves, we demonstrate the ability of numerical models to test successfully working hypotheses on ice-shelf thickness distributions. Ice velocities, obtained by diagnostic models of Filchner–Ronne Ice Shelf that use different ice-thickness distributions, are compared with measured ice velocities. This comparison demonstrates that the model employing regions of thin ice in the central part of the ice shelf yields velocities significantly different from the field data. We therefore conclude that zones of thin ice on Filchner–Ronne ice Shelf are unlikely. This conclusion has recently been confirmed by field measurements.