Mapping Damping Ratio From ICESat-derived Surface Topography Over The Antarctic Ice Sheet

The Ice, Cloud, and land Elevation Satellite (ICESat) has acquired detailed surface topography (to ±86° latitude) that allows the investigation of the relation between surface and bedrock undulations from ice sheet margins to regions further inland, where accurate surface topography was not previously available. Using ICESat data combined with bedrock topography from BEDMAP along Antarctic ice-sheet flowlines, we perform power-spectral analyses to derive the mean damping ratio between surface and bedrock undulations for 40-km sections of the flowlines. The derived ratio, ranging effectively between 1 and 0, consistently decreases from the coast towards the inland. Variations of the surface slope along flowlines tend to be in phase with the bedrock elevation profile, implying that the ice sheet surface is affected by the bedrock topography even in many inland regions where the ice is thicker. The analysis provides the essential information that leads to the further analysis for the derivation of ice flow properties over the ice sheet based on the topography data.