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Estimating basal properties of ice streams from surface measurements: a non-linear Bayesian inverse approach applied to synthetic data

Raymond, M.J.; Gudmundsson, G.H.. 2009 Estimating basal properties of ice streams from surface measurements: a non-linear Bayesian inverse approach applied to synthetic data. Cryosphere, 3 (2). 265-278. 10.5194/tc-3-265-2009

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Abstract/Summary

We propose a new approach to indirectly estimate basal properties of ice streams, i.e. bedrock topography and basal slipperiness, from observations of surface topography and surface velocities. We demonstrate how a maximum a posteriori estimate of basal conditions can be determined using a Bayesian inference approach in a combination with an analytical linearisation of the forward model. Using synthetic data we show that for non-linear media and non-linear sliding law only a few forward-step model evaluations are needed for convergence. The forward step is solved with a numerical finite-element model using the full Stokes equations. The Frechet derivative of the forward function is approximated through analytical small-perturbation solutions. This approximation is a key feature of the method and the effects of this approximation on model performance are analyzed. The number of iterations needed for convergence increases with the amplitude of the basal perturbations, but generally less than ten iterations are needed.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.5194/tc-3-265-2009
Programmes: BAS Programmes > Polar Science for Planet Earth (2009 - ) > Ice Sheets
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.
NORA Subject Terms: Glaciology
Earth Sciences
Date made live: 23 Aug 2010 08:09
URI: http://nora.nerc.ac.uk/id/eprint/10618

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