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| Titel |
Seabed topography beneath Larsen C Ice Shelf from seismic soundings |
| VerfasserIn |
A. M. Brisbourne, A. M. Smith, E. C. King, K. W. Nicholls, P. R. Holland, K. Makinson |
| 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 ; 8, no. 1 ; Nr. 8, no. 1 (2014-01-02), S.1-13 |
| Datensatznummer |
250116002
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| Publikation (Nr.) |
 copernicus.org/tc-8-1-2014.pdf |
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| Zusammenfassung |
| Seismic reflection soundings of ice thickness and seabed depth were acquired
on the Larsen C Ice Shelf in order to test a sub-ice shelf bathymetry model
derived from the inversion of IceBridge gravity data. A series of lines was
collected, from the Churchill Peninsula in the north to the Joerg Peninsula
in the south, and also towards the ice front. Sites were selected using the
bathymetry model derived from the inversion of free-air gravity data to
indicate key regions where sub-ice shelf oceanic circulation may be affected
by ice draft and seabed depth. The seismic velocity profile in the upper
100 m of firn and ice was derived from shallow refraction surveys at a number of
locations. Measured temperatures within the ice column and at the ice base
were used to define the velocity profile through the remainder of the ice
column. Seismic velocities in the water column were derived from previous in
situ measurements. Uncertainties in ice and water cavity thickness are in
general < 10 m. Compared with the seismic measurements, the
root-mean-square error in the gravimetrically derived bathymetry at the
seismic sites is 162 m. The seismic profiles prove the non-existence of
several bathymetric features that are indicated in the gravity inversion
model, significantly modifying the expected oceanic circulation beneath the
ice shelf. Similar features have previously been shown to be highly
significant in affecting basal melt rates predicted by ocean models. The
discrepancies between the gravity inversion results and the seismic
bathymetry are attributed to the assumption of uniform geology inherent in
the gravity inversion process and also the sparsity of IceBridge flight
lines. Results indicate that care must be taken when using bathymetry models
derived by the inversion of free-air gravity anomalies. The bathymetry
results presented here will be used to improve existing sub-ice shelf ocean
circulation models. |
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