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| Titel |
Layer disturbances and the radio-echo free zone in ice sheets |
| VerfasserIn |
R. Drews, O. Eisen, I. Weikusat, S. Kipfstuhl, A. Lambrecht, D. Steinhage, F. Wilhelms, Heinrich Miller  |
| 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. 2 ; Nr. 3, no. 2 (2009-08-25), S.195-203 |
| Datensatznummer |
250000937
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| Publikation (Nr.) |
 copernicus.org/tc-3-195-2009.pdf |
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| Zusammenfassung |
| Radio-echo sounding of the Antarctic and Greenlandic ice sheets often reveals
a layer in the lowest hundreds of meters above bedrock more or less free of
radio echoes, known as the echo-free zone (EFZ). The cause of this feature is
unclear, so far lacking direct evidence for its origin. We compare echoes
around the EPICA drill site in Dronning Maud Land, Antarctica, with the
dielectric properties, crystal orientation fabrics and optical stratigraphy
of the EPICA-DML ice core. We find that echoes disappear in the depth range
where the dielectric contrast is blurred, and where the coherency of the
layers in the ice core is lost due to disturbances caused by the ice flow. At
the drill site, the EFZ onset at ~2100 m marks a boundary, below which
the ice core may have experienced flow induced disturbances on various
scales. The onset may indicate changing rheology which needs to be
accounted for in the modeling of ice sheet dynamics. |
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