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

• Published in: Journal of glaciology Vol. 52; no. 176; pp. 17 - 30
• Main Authors: Horwath, Martin, Dietrich, Reinhard, Baessler, Michael, Nixdorf, Uwe, Steinhage, Daniel, Fritzsche, Diedrich, Damm, Volkmar, Reitmayr, Gernot
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 2006; International Glaciological Society
• Subjects: Earth, ocean, space; Exact sciences and technology; External geophysics; Snow. Ice. Glaciers; Antarctica; glaciology; time variations; mass balance; cartography; Layer thickness; Floating ice; firn; Polar Cap; Ice shelf; polar regions; Glacier balance; ice caps; Observation data; Flow velocity; Snow accumulation
• ISSN: 0022-1430; 1727-5652
• DOI: 10.3189/172756506781828953

Extensive observations on Nivlisen, an ice shelf on Antarctica’s Atlantic coast, are analyzed and combined to obtain a new description of its complex glaciological regime. We generate models of ice thickness (primarily from ground-penetrating radar), ellipsoidal ice surface height (primarily from ERS-1 satellite altimetry), freeboard height (by utilizing precise sea surface information) and ice-flow velocity (from ERS-1/-2 SAR interferometry and GPS measurements). Accuracy assessments are 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 to ≈16m) which we attribute to the transition from an ablation area to 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 kg m–2 a–1, which suggests bottom melting processes 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 question of temporal changes remains open from the data at hand, and we recommend further observations and analyses for its solution.