A method for separating Antarctic postglacial rebound and ice mass balance using future ICESat Geoscience Laser Altimeter System, Gravity Recovery and Climate Experiment, and GPS satellite data

Abstract

[1] Measurements of ice elevation from the Geoscience Laser Altimeter System (GLAS) aboard the Ice, Cloud, and Land Elevation Satellite can be combined with time-variable geoid measurements from the Gravity Recovery and Climate Experiment (GRACE) satellite mission to learn about ongoing changes in polar ice mass and viscoelastic rebound of the lithosphere under the ice sheet. We estimate the accuracy in recovering the spatially varying ice mass trend and postglacial rebound signals for Antarctica, from combining 5 years of simulated GRACE and GLAS data. We obtain root-mean square accuracies of 5.3 and 19.9 mm yr À1 for postglacial rebound and ice mass trend, respectively, when smoothed over 250 km scales. The largest source of error in the combined signals is the effect of the unknown time-variable accumulation on the density of the ice column. To estimate this contribution and so obtain better estimates of ice mass trend and postglacial rebound, we add Global Positioning System (GPS) measurements of vertical velocities as additional constraints. Using an empirical relation between the errors in postglacial rebound and ice mass trend that result from the unknown density variation within the ice column, we are able to solve for all three unknowns in the problem: ice mass trend, postglacial rebound, and the snow compaction trend. The addition of a plausible distribution of GPS measurements reduces the errors in estimates of postglacial rebound and ice mass trend to 3.4 and 15.9 mm yr À1 , respectively.

Detection of Continental Hydrology and Glaciology Signals from GRACE: A Review

“…Thus removing from GRACE the PGR effects that still cannot be modelled accurately results in the addition of important uncertainties in the mass balance estimates. Velicogna and Wahr (2002) have shown earlier that the detection of PGR was possible by combining different satellite techniques. These authors used 5 years of simulated GRACE and Laser GLAS data smoothed over 250-km scales, and found level accuracies of 5.3 mm/yr and 20 mm/yr for PGR signature and ice mass trend, respectively, over the whole of Antarctica.…”

GRACE, time-varying gravity, Earth system dynamics and climate change

“…Riva et al [216] published a first AIS trend estimate which did not rely on GIA modelling, but separated ice-mass loss from GIA by combining the GRACE gravity data with ICESat surface elevation changes. This concept, based on earlier theoretical work of Velicogna and Wahr [217], relies on the fact that GRACE mass and ICESat elevation observations bear different sensitivities to GIA and ice-mass loss, respectively. Their GIA correction of 100±67 Gt/yr was considerably smaller than the correction used in Velicogna and Wahr [148] (176±72 Gt/yr).…”

Contribution of GRACE Satellite Gravimetry in Global and Regional Hydrology, and in Ice Sheets Mass Balance

“…Consequently, removing PGR that still cannot be modelled accurately represent a source of important errors. Velicogna & Wahr (2002) have shown earlier that the detection of PGR remains possible by combination of different satellite techniques, using 5 years of simulated GRACE and Laser GLAS data over the whole Antarctica. However, an effective extraction of PGR signals using GRACE products still needs to be demonstrated.…”