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| Titel |
Estimating basal properties of ice streams from surface measurements: a non-linear Bayesian inverse approach applied to synthetic data |
| VerfasserIn |
M. J. Raymond, G. H. Gudmundsson |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1994-0416
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| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 3, no. 2 ; Nr. 3, no. 2 (2009-12-23), S.265-278 |
| Datensatznummer |
250000942
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| Publikation (Nr.) |
 copernicus.org/tc-3-265-2009.pdf |
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| Zusammenfassung |
| 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 Fréchet 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. |
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