Radar surveys of the Rutford Ice Stream onset zone, West Antarctica: indications of flow (in)stability?

Woodward, John and King, Edward (2009) Radar surveys of the Rutford Ice Stream onset zone, West Antarctica: indications of flow (in)stability? Annals of Glaciology, 50 (51). pp. 57-62. ISSN 0260-3055

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Official URL: http://dx.doi.org/10.3189/172756409789097469

Abstract

We present 1 and 100 MHz ground-based radar data from the onset region of Rutford Ice Stream, West Antarctica, which indicate the form and internal structure of isochrones. In the flow-parallel lines, modelled isochrone patterns reproduce the gross pattern of the imaged near-surface layers, assuming steady-state flow velocity from GPS records and the current accumulation rate for the last 200 years. We interpret this as indicating overall stability in flow in the onset region of Rutford Ice Stream throughout this period. However, in the cross-flow lines some local variability in accumulation is seen in areas close to the ice-stream margin where a number of tributaries converge towards the ice-stream onset zone. Episodic surface lowering events are observed followed by rapid fill episodes. The fill events indicate deposition towards the northwest, most likely generated by storm winds, which blow at an oblique angle to ice flow. More problematic is explaining the generation of episodic surface lowering in this area. We speculate this may be due to: changing ice-flow direction in the complex tributary area of the onset zone; a change in basal sediments or sedimentary landforms; a change in basal melt rates or water supply; or episodic lake drainage events in the fjord systems of the Ellsworth Subglacial Highlands. The study highlights the difficulty of assessing flow stability in the complex onset regions of West Antarctic ice streams.

Item Type: Article
Uncontrolled Keywords: Rutford ice stream (Antarctica), ground penetrating radar
Subjects: F800 Physical and Terrestrial Geographical and Environmental Sciences
Department: Faculties > Engineering and Environment > Geography
Depositing User: EPrint Services
Date Deposited: 03 Sep 2009 09:07
Last Modified: 10 Aug 2015 11:26
URI: http://nrl.northumbria.ac.uk/id/eprint/756

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