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On the limit to resolution and information on basal properties obtainable from surface data on ice streams

Gudmundsson, G.H.; Raymond, M.. 2008 On the limit to resolution and information on basal properties obtainable from surface data on ice streams. Cryosphere, 2 (2). 167-178. 10.5194/tc-2-167-2008

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Abstract/Summary

An optimal estimation method for simultaneously determining both basal slipperiness and basal topography from variations in surface flow velocity and topography along a flow line on ice streams and ice sheets is presented. We use Bayesian inference to update prior statistical estimates for basal topography and slipperiness using surface measurements along a flow line. Our main focus here is on how errors and spacing of surface data affect estimates of basal quantities and on possibly aliasing/mixing between basal slipperiness and basal topography. We find that the effects of spatial variations in basal topography and basal slipperiness on surface data can be accurately separated from each other, and mixing in retrieval does not pose a serious problem. For realistic surface data errors and density, small-amplitude perturbations in basal slipperiness can only be resolved for wavelengths larger than about 50 times the mean ice thickness. Bedrock topography is well resolved down to horizontal scale equal to about one ice thickness. Estimates of basal slipperiness are not significantly improved by accurate prior estimates of basal topography. However, retrieval of basal slipperiness is found to be highly sensitive to unmodelled errors in basal topography.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.5194/tc-2-167-2008
Programmes: BAS Programmes > Global Science in the Antarctic Context (2005-2009) > Glacial Retreat in Antarctica and Deglaciation of the Earth System
ISSN: 1994-0416
Additional Information. Not used in RCUK Gateway to Research.: Open access article made available under a CC-BY Creative Commons Attribution license.
Additional Keywords: Ice streams, Flow
NORA Subject Terms: Glaciology
Date made live: 24 Mar 2009 13:57
URI: http://nora.nerc.ac.uk/id/eprint/6800

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