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| Titel |
Surface undulations of Antarctic ice streams tightly controlled by bedrock topography |
| VerfasserIn |
J. Rydt, G. H. Gudmundsson, H. F. J. Corr, P. Christoffersen |
| 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 ; 7, no. 2 ; Nr. 7, no. 2 (2013-03-01), S.407-417 |
| Datensatznummer |
250017939
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| Publikation (Nr.) |
 copernicus.org/tc-7-407-2013.pdf |
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| Zusammenfassung |
| Full Stokes flow-line models predict that fast-flowing ice streams transmit
information about their bedrock topography most efficiently to the surface
for basal undulations with length scales between 1 and 20 times the mean ice
thickness. This typical behaviour is independent of the precise values of the
flow law and sliding law exponents, and should be universally observable.
However, no experimental evidence for this important theoretical prediction
has been obtained so far, hence ignoring an important test for the physical
validity of current-day ice flow models. In our work we use recently acquired
airborne radar data for the Rutford Ice Stream and Evans Ice Stream, and we
show that the surface response of fast-flowing ice is highly sensitive to
bedrock irregularities with wavelengths of several ice thicknesses. The
sensitivity depends on the slip ratio, i.e. the ratio between mean basal
sliding velocity and mean deformational velocity. We find that higher values
of the slip ratio generally lead to a more efficient transfer, whereas the
transfer is significantly dampened for ice that attains most of its surface
velocity by creep. Our findings underline the importance of bedrock
topography for ice stream dynamics on spatial scales up to 20 times the mean
ice thickness. Our results also suggest that local variations in the flow
regime and surface topography at this spatial scale cannot be explained by
variations in basal slipperiness. |
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