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Titel |
Characterizing ice domes in Dronning Maud Land (Antarctica) using geophysical methods and ice-flow models |
VerfasserIn |
R. Drews, O. Eisen, D. Steinhage, C. Martin, F. Pattyn |
Konferenz |
EGU General Assembly 2012
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 14 (2012) |
Datensatznummer |
250060867
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Zusammenfassung |
Many ice rises are situated in a drawn-out ice-shelf belt boardering the Dronning Maud Land
coast. The defined catchment area and high accumulation rates appear suited for new
ice-core climate records focusing on the last 2000 and 40000 years. The internal
stratigraphy of ice rises is imprinted by the flow history of their surrounding, which, if
combined with ice-flow models, enables the deduction of past flow patterns and
changes thereof. The focus of this study is set on Halvfarryggen ice dome, which
is characterized by using remote sensing techniques in combination with on-site
radar and GPS measurements. Airborne and ground-based radar surveys image
bedrock topography and internal layering in the vicinity of the dome, which is located
near a triple junction where three ice divides merge. The surface topography is
determined by a combination of different remote-sensing techniques resulting in an
elevation model with a grid spacing of 100Â m x 100Â m and a standard deviation
along ground control points of 11Â m. The internal layering as seen via radar bends
upwards beneath the divides, indicating the operation of the Raymond effect. The
upward-bending increases in amplitude with larger depths down to the lower third of
the ice column, where the isochrone arch develops into a double bump in some
radargrams. We visualize the three dimensional characteristics in internal layering in a
15–20Â km radius around the dome. Accumulation estimates from internal layers near the
surface vary from 400–1670 kg/(m2a) with an asymmetry caused by preferred wind
directions and changing surface slope. We use the derived datasets as input for a
two dimensional full Stokes, anisotropic ice-flow model to predict the age–depth
relationship and compare the modelled isochrones with the radar layer architecture. In the
vicinity of the dome we estimate 13Â ka old ice at 90% of the total ice thickness. |
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