Complex Greenland outlet glacier flow captured

Published: Jun 1, 2016 by The PISM Authors

The paper is based on PISM simulations of 600 m grid resolution over the entire Greenland ice sheet. All parts of the ice sheet, and each outlet glacier in particular, see the same physics. The quality of this flow model for 29 major outlet glaciers is assessed by comparison with present-day-observed surface velocities at cross-flow near-ocean profiles, often called “flux gates”. The main result is that the majority of the outlet glaciers show strong correlation between modeled and observed velocity. The paper demonstrates that outlet glacier flow can be captured with high fidelity if ice thickness is well-constrained and if vertical shearing as well as membrane stresses are included in the model. While it is not clear that solving the full-stress configuration would improve the fit, it is clear that the shallow hybrid model can be applied at higher resolution and for longer-duration runs. Inversion of surface properties for individual glaciers is not essential to reproduce the overall flow pattern. Spatial variability in flow can be explained in large part by the spatial variability in ice thickness.