A hydrologically coupled higher-order flow-band model of ice dynamics with a Coulomb friction sliding law
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| Authors: | Pimentel, S; Flowers, GE; Schoof, CG |
| Year: | 2010 |
| Journal: | J. Geophys. Res.-Earth Surf. 115 Article Link (DOI) |
| Title: | A hydrologically coupled higher-order flow-band model of ice dynamics with a Coulomb friction sliding law |
| Abstract: | The influence of hydrologic transience and heterogeneity on basal motion is an often-neglected aspect of numerical ice-flow models. We present a flow-band model of glacier dynamics with a Coulomb friction sliding law that is coupled to a model of the basal drainage system by means of subglacial water pressure. The ice-flow model contains "higher-order" stress gradients from the Stokes flow approximation originally conceived by Blatter (1995). The resulting system of nonlinear equations is solved using a modified Picard iteration that is shown to improve the rate of convergence. A parameterization of lateral shearing is included to account for the effects of three-dimensional geometry. We find that lateral drag has a discernible effect on glacier speed even when glacier width exceeds glacier length. Variations in flow-band width are shown to have a greater influence on flow line speed than either different valley cross-sectional shapes or the presence or absence of glacier sliding along valley walls. Modeled profiles of subglacial water pressure depart significantly from pressures prescribed as a uniform fraction of overburden, thus producing profiles of glacier sliding that are distinctly different from those that would be described by a sliding law controlled by overburden pressures. Simulations of hydraulically driven glacier acceleration highlight the value of including a representation of basal hydrology in models aiming for improved predictive capability of glacier dynamics. |
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