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

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-penetrating radar), 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). 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 area to an accumulation area. We compute mass flux and mass balance parameters. The combined effect of bottom mass balance and temporal change averaged over an essential part of Nivlisen is -654± 170 kg m-2a-1 which suggests bottom melting processes to dominate. We discuss our results, in particular in view of temporal ice mass changes and basal processes.