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.
Helmholtz Research Programs > MARCOPOLI (2004-2008) > POL6-Earth climate variability since the Pliocene