Estimation of ice-sheet motion using satellite radar interferometry: method and error analysis with application to Humboldt Glacier, Greenland

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Abstract
Satellite radar interferometry provides glaciologists with an important new tool for determining the motion and topography of large ice sheets. We examine the sources of error in interferometrically derived ice-motion measurements, including those errors due to inaccurate estimates of the interfero-metric baseline. Several simulations are used to assess baseline accuracy in terms of tie-point error and the number and distribution of tie points. These results give insight into how best to select tie points, and also demonstrate the level of accuracy that can be achieved. Examination of two representative cases likely to occur in mapping ice-sheet motion leads to the conclusion that with adequate tie-point information ice velocity can be measured accurately to within a few meters per year. A method to correct horizontal velocity estimates for the effect of vertical displacement using surface slopes is also developed. Finally, we estimate the single-component velocity field for an area on Humboldt Glacier, northern Greenland, using interferograms formed from ERS-1 SAR image. We estimatе that these velocity measurements are accurate to within 2.3 m year1.