An analysis of balance velocities over the Greenland ice sheet and comparison with synthetic aperture radar interferometry
Abstract:Balance velocities for the Greenland ice sheet have been calculated from a new digital elevation model (DEM), accumulation rates and an existing ice-thickness grid, using a fully two-dimensional finite-difference scheme. The pattern of velocities is compared with velocities derived from synthetic-aperture radar (SAR) interferometry for three different regions of the ice sheet. Differences between the two estimates of velocity highlight the respective strengths and weaknesses of the datasets and techniques used. A comparison with ten global positioning system-derived velocities indicates that the balance-velocity scheme and input datasets used here provide a remarkably good representation of the velocity distribution inland from the margins. These balance-velocity data, therefore, could help constrain numerical ice-sheet models. The balance velocities were found to be unreliable close to the ice-sheet margins due to larger errors in ice thickness, surface slope and ablation rate in this region. Comparison of the balance velocities with SAR interferometry in the region of the "Northeast Greenland Ice Stream'' indicates the importance of the smoothing distance that must be applied to the DEM before calculating balance velocities. A smoothing distance of 20 times the ice thickness gave good agreement between the two measures of velocity.
Document Type: Research Article
Publication date: 2000-01-01
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- The Journal of Glaciology is published six times per year. It accepts submissions from any discipline related to the study of snow and ice. All articles are peer reviewed. The Journal is included in the ISI Science Citation Index.
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