The Nivlisen, an Antarctic ice shelf in Dronning Maud Land: geodetic-glaciological results from a combined analysis of ice thickness, ice surface height and ice flow observations


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dfritsch [ at ] awi-potsdam.de

Abstract

Extensive observations on Nivlisen, an ice shelf at Antarctica's Atlantic coast, are analysed and combined to achieve a new-quality description of its complex glaciological regime. We generate models of ice thickness (primarily from ground-penetratingradar), ellipsoidal ice surface height (primarily from ERS-1 satellite altimetry), freeboard height (by utilising precise sea surface information), and ice flow velocity(from ERS-1/2 SAR interferometry and GPS measurements). Accuracy assessmentsare included. Exploiting the hydrostatic equilibrium relation we infer the 'apparent air layer thickness' as a useful measure for a glacier's density deviation from a pure ice body. This parameter exhibits a distinct spatial variation (ranging from 2 m to 16 m) which we attribute to the transition from an ablation areato an accumulation area. We compute mass flux and mass balance parameters on a local and areally integrated scale. The combined effect of bottom mass balance and temporal change averaged over an essential part of Nivlisen is -654±170 kgm2a-1 which suggests bottom melting processes to dominate. We discuss our results in view of temporal ice mass changes (including remarks on historical observations),basal processes, near-surface processes, and ice-flow dynamical features. The questionfor temporal changes remains open from the data at hand, and we recommendfurther observations and analyses for its solution.



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Scopus/ISI peer-reviewed
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Published
Eprint ID
10564
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Horwath, M. , Dietrich, R. , Baessler, M. , Nixdorf, U. , Steinhage, D. , Fritzsche, D. , Damm, V. and Reitmayr, G. (2006): The Nivlisen, an Antarctic ice shelf in Dronning Maud Land: geodetic-glaciological results from a combined analysis of ice thickness, ice surface height and ice flow observations , Journal of Glaciology, 52 (176), pp. 17-30 .


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