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| Titel |
Nonlinear interaction between ocean tides and the Larsen C Ice Shelf system |
| VerfasserIn |
Matt King, G. Hilmar Gudmundsson, Keith Makinson |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250054483
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| Zusammenfassung |
| We report on GPS records of flow of the Larsen C Ice Shelf, spanning 2 months to 2 years.
Variations in speed are evident at periods from a few hours to ~182Â days, including
semi-diurnal, diurnal and ~14.76Â days. At fortnightly periods the ice shelf varies by ±10%
from its long-term speed but at diurnal timescales it is up to ±100%. The fortnightly signal is
near synchronous across the ice shelf pointing to a common source mechanism. The diurnal
and higher frequency signal has similar structure across the ice shelf, but with some phase
differences as well as amplification of parts of the signal toward the ice shelf front. We
model the modulation of flow as a non-linear function of basal shear stress (ËÏ b)
including tidal perturbations in the ice shelf grounding zone. Close agreement with the
observations is found with ËÏ b=10Â kPa and exponent m-3, suggesting the presence
of a viscous and non-linear till in the grounding zone, at least for Mobiloil and
Cabinet inlets, and thereby providing new boundary conditions for modeling the
Larsen C Ice Shelf system. While the fortnightly signal and the structure of the
diurnal and higher frequency signal is closely reproduced by the model, it does not
explain the entire signal, notably the amplification of diurnal and higher frequency
signal toward the ice shelf front or relatively small lateral ice shelf motion. We
suggest that an elastic response to tidal tilting of the ice shelf may be responsible. |
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