| Important constraints on estimates of future sea-level change are provided by knowledge of ice-mass changes in the polar regions. However, recent estimates of ice-mass balance in Antarctica using Gravity Recovery and Climate Experiment (GRACE) data sets are dominated by uncertainties in the correction for glacial isostatic adjustment (GIA). In order to better constrain the GIA models, accurate and precise surface displacement measurements are necessary. However, the current network of continuous GPS receivers is too sparse to in Antarctica to distinguish between competing hypotheses. On the other hand, synthetic aperture radar (SAR) data have been collected over Antarctica for the last 16 years, and there are currently more satellites collecting SAR data than ever before. We propose to process SAR data from various sensors using recently developed time-series SAR interferometry techniques, to determine relative vertical velocities in key regions of Antarctica where there is rock exposed. We will tie these relative velocities to a fixed reference frame using the sparse network of continuous GPS stations. We will use the resulting probability distribution of absolute velocities to restrict the confidence range of existing GIA models, and may even be able to rule some out. This will lead to a narrowing of the range of plausible present-day ice-mass loss estimates, which are an important input into models of future sea-level rise. |
