Regional glacial isostatic adjustment in Antarctica estimated from GRACE, Enivsat/ICESat and GPS observations (ESA-STSE project REGINA).

The viscoelastic adjustment of the solid Earth to former glacial loads in Antarctica and the associated gravity-field change and surface displacement is a major uncertainty in determining the mass balance of the ice sheet from satellite gravimetry, and, to a lesser extent, altimetry measurements such as CryoSat-2. On the other hand, measurements of GIA inferred from the geodetic observations provide valuable information on the glacial history and the lithosphere and mantle properties in Antarctica. Here, we present an improved regional GIA estimate based on GRACE, Envisat/ICESat and GPS measurements. Making use of the different sensitivities of the observations to surface-mass and solid Earth processes, we derive an improved GIA field, using an ensemble of viscoelastic response functions to a disc load forcing. The estimated GIA signal is interpreted for recent ice load changes in West Antarctica in the presence of a low-viscous upper mantle, and evaluated for correcting GRACE and CryoSat-2 measurements when determining present-day ice-mass balance in Antarctica. The results are part of the ESA-STSE project REGINA, www.regina-science.eu.