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Parameterization of Basal Friction near Grounding Lines in Ice Sheet Models

Investigating the impact of ocean connectivity on basal hydrology in ice-sheet models using a new friction law parameterization. Effective-pressure parameter p, varying between 0 (no connectivity) and 1 (full connectivity), tested in MISMIP experiments. Developed 1-D model compared against Chebyshev solution at 7 resolutions from 3.2 to 0.05 km. Improves model accuracy at grounding lines at ~1 km resolution, reducing computational cost significantly. (496 characters)

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Parameterization of Basal Friction near Grounding Lines in Ice Sheet Models

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  1. Parameterization of basal friction near grounding lines in a one-dimensional ice sheet model Maximum error in grounding-line position for the MISMIP experiments. The black contour line represents a 30 km error deemed to be sufficiently small. Larger values of p(increased connectivity) yield smaller errors for a given resolution. Objective The basal friction law is a key component of ice-sheet models. We studied the influence of ocean connectivity to the ice-sheet basal hydrology system using a new parameterization of the basalwater pressure in the friction law. • Approach • Introduced an effective-pressure parameter p varying between 0 (no connectivity) and 1 (full connectivity). • Used standard marine ice sheet (MISMIP) experiments for model testing. • Developed a 1-D model and applied it at 7 resolutions between 3.2 and 0.05 km. • Compared results to a highly accurate numerical Chebyshev solution. Impact Fixed-grid ice-sheet models typically require grid resolution of 200 m or less to accurately model grounding-line retreat driven by climate change. Use of a physically plausible parameterization of ocean connectivity in these models could give accurate results at ~1 km resolution, greatly reducing computational cost. Reference: : Leguy, G. R., Asay-Davis, X. S., and Lipscomb, W. H.: Parameterization of basal friction near grounding lines in a one-dimensional ice sheet model, The Cryosphere, 8, 1239-1259, doi:10.5194/tc-8-1239-2014, 2014.

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