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| Titel |
Tidally induced velocity variations of the Beardmore Glacier, Antarctica, and their representation in satellite measurements of ice velocity |
| VerfasserIn |
O. J. Marsh, W. Rack, D. Floricioiu, N. R. Golledge, W. Lawson |
| 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. 5 ; Nr. 7, no. 5 (2013-09-10), S.1375-1384 |
| Datensatznummer |
250085154
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| Publikation (Nr.) |
 copernicus.org/tc-7-1375-2013.pdf |
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| Zusammenfassung |
| Ocean tides close to the grounding line of outlet glaciers around Antarctica
have been shown to directly influence ice velocity, both linearly and
non-linearly. These fluctuations can be significant and have the potential to
affect satellite measurements of ice discharge, which assume displacement
between satellite passes to be consistent and representative of annual means.
Satellite observations of horizontal velocity variation in the grounding zone
are also contaminated by vertical tidal effects, the importance of which is
highlighted here in speckle tracking measurements. Eight TerraSAR-X scenes
from the grounding zone of the Beardmore Glacier are analysed in conjunction
with GPS measurements to determine short-term and decadal trends in ice
velocity. Diurnal tides produce horizontal velocity fluctuations of >50%
on the ice shelf, recorded in the GPS data 4 km downstream of the grounding
line. This variability decreases rapidly to <5% only 15 km upstream of the
grounding line. Daily fluctuations are smoothed to <1% in the 11-day
repeat pass TerraSAR-X imagery, but fortnightly variations over this period
are still visible and show that satellite-velocity measurements can be
affected by tides over longer periods. The measured tidal displacement
observed in radar look direction over floating ice also allows the grounding
line to be identified, using differential speckle tracking where phase
information cannot be easily unwrapped. |
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