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| Titel |
A new 1 km digital elevation model of the Antarctic derived from combined satellite radar and laser data – Part 1: Data and methods |
| VerfasserIn |
J. L. Bamber, J. L. Gomez-Dans, J. A. Griggs |
| 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. 1 ; Nr. 3, no. 1 (2009-05-04), S.101-111 |
| Datensatznummer |
250000788
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| Publikation (Nr.) |
 copernicus.org/tc-3-101-2009.pdf |
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| Zusammenfassung |
| Digital elevation models (DEMs) of the whole of Antarctica have been
derived, previously, from satellite radar altimetry (SRA) and limited
terrestrial data. Near the ice sheet margins and in other areas of steep
relief the SRA data tend to have relatively poor coverage and accuracy. To
remedy this and to extend the coverage beyond the latitudinal limit of the
SRA missions (81.5° S) we have combined laser altimeter measurements
from the Geosciences Laser Altimeter System onboard ICESat with SRA data
from the geodetic phase of the ERS-1 satellite mission. The former provide
decimetre vertical accuracy but with poor spatial coverage. The latter have
excellent spatial coverage but a poorer vertical accuracy. By combining the
radar and laser data using an optimal approach we have maximised the
vertical accuracy and spatial resolution of the DEM and minimised the number
of grid cells with an interpolated elevation estimate. We assessed the
optimum resolution for producing a DEM based on a trade-off between
resolution and interpolated cells, which was found to be 1 km. This resulted
in just under 32% of grid cells having an interpolated value. The
accuracy of the final DEM was assessed using a suite of independent airborne
altimeter data and used to produce an error map. The RMS error in the new
DEM was found to be roughly half that of the best previous 5 km resolution,
SRA-derived DEM, with marked improvements in the steeper marginal and
mountainous areas and between 81.5 and 86° S. The DEM contains a wealth
of information related to ice flow. This is particularly apparent for the
two largest ice shelves – the Filchner-Ronne and Ross – where the surface
expression of flow of ice streams and outlet glaciers can be traced from the
grounding line to the calving front. The surface expression of subglacial
lakes and other basal features are also illustrated. We also use the DEM to
derive new estimates of balance velocities and ice divide locations. |
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