Articles | Volume 8, issue 4
The Cryosphere, 8, 1239–1259, 2014
The Cryosphere, 8, 1239–1259, 2014

Research article 18 Jul 2014

Research article | 18 Jul 2014

Parameterization of basal friction near grounding lines in a one-dimensional ice sheet model

G. R. Leguy1,2, X. S. Asay-Davis2,3,4, and W. H. Lipscomb2 G. R. Leguy et al.
  • 1New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro,
    New Mexico 87501, USA
  • 2Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
  • 3Courant Institute of Mathematical Sciences, New York University, 251 Mercer Street,
    New York, New York 10012-1185, USA
  • 4Potsdam Institute for Climate Impact Research, Telegraphenberg A 31, 14473 Potsdam, Germany

Abstract. Ice sheets and ice shelves are linked by the transition zone, the region where flow dominated by vertical shear stress makes a transition to flow dominated by extensional stress. Adequate resolution of the transition zone is necessary for numerically accurate ice sheet–ice shelf simulations. The required resolution depends on how the basal physics is parameterized. We propose a~new, simple parameterization of the effective pressure near the grounding line, combined with an existing friction law linking effective pressure to basal stress and sliding, in a one-dimensional, fixed-grid, vertically integrated model. This parameterization represents connectivity between the basal hydrological system and the ocean in the transition zone. Our model produces a smooth transition between finite basal friction in the ice sheet and zero basal friction in the ice shelf. In a set of experiments based on the Marine Ice Sheet Model Intercomparison Project (MISMIP), we show that with a smoother basal shear stress, the model yields accurate steady-state results at a fixed-grid resolution of ~1 km.