Abstract
Abstract. The poorly known correction for the ongoing deformation of the solid Earth caused by glacial isostatic adjustment (GIA) is a major uncertainty in determining the mass balance of the Antarctic ice sheet from measurements of satellite gravimetry and to a lesser extent satellite altimetry. In the past decade, much progress has been made in consistently modeling ice sheet and solid Earth interactions; however, forward-modeling solutions of GIA in Antarctica remain uncertain due to the sparsity of constraints on the ice sheet evolution, as well as the Earth's rheological properties. An alternative approach towards estimating GIA is the joint inversion of multiple satellite data – namely, satellite gravimetry, satellite altimetry and GPS, which reflect, with different sensitivities, trends in recent glacial changes and GIA. Crucial to the success of this approach is the accuracy of the space-geodetic data sets. Here, we present reprocessed rates of surface-ice elevation change (Envisat/Ice, Cloud,and land Elevation Satellite, ICESat; 2003–2009), gravity field change (Gravity Recovery and Climate Experiment, GRACE; 2003–2009) and bedrock uplift (GPS; 1995–2013). The data analysis is complemented by the forward modeling of viscoelastic response functions to disc load forcing, allowing us to relate GIA-induced surface displacements with gravity changes for different rheological parameters of the solid Earth. The data and modeling results presented here are available in the PANGAEA database (https://doi.org/10.1594/PANGAEA.875745). The data sets are the input streams for the joint inversion estimate of present-day ice-mass change and GIA, focusing on Antarctica. However, the methods, code and data provided in this paper can be used to solve other problems, such as volume balances of the Antarctic ice sheet, or can be applied to other geographical regions in the case of the viscoelastic response functions. This paper presents the first of two contributions summarizing the work carried out within a European Space Agency funded study: Regional glacial isostatic adjustment and CryoSat elevation rate corrections in Antarctica (REGINA).
Highlights
Glacial isostatic adjustment (GIA), the viscoelastic deformation of the solid Earth in response to climate-driven ice and water mass redistribution on its surface, is poorly constrained in Antarctica
The elevation rates derived from ICESat and Envisat are corrected for changes in the firn layer thickness using the firn compaction model of Ligtenberg et al (2011), which is driven by the regional atmosphere and climate model RACMO2/ANT (Lenaerts et al, 2012)
We have presented refined temporal linear trends in surface elevation, gravity field change and bedrock displacement based on Envisat–ICESat (2003– 2009), Gravity Recovery and Climate Experiment (GRACE) (2003–2009) and GPS (1995–2013), respectively
Summary
Glacial isostatic adjustment (GIA), the viscoelastic deformation of the solid Earth in response to climate-driven ice and water mass redistribution on its surface, is poorly constrained in Antarctica. The rates of surface-ice elevation change from Envisat and ICESat satellite altimetry are improved by combining both data sets based on their respective uncertainties, increasing the spatial coverage and accuracy of the elevation rates The viscoelastic response functions are based on Earth model parameters potentially suitable to other geographical regions, as well; they are useful for similar studies combining different data sets of geodetic observables, surface deformation, gravity field change and topographic change in glaciated areas. The actual method of the joint inversion is described in a second contribution of the Regional glacial isostatic adjustment and CryoSat elevation rate corrections in Antarctica (REGINA) project team (Sasgen et al, 2017a) In this second paper, the resulting GIA estimate is compared to previous studies. The elevation rate and its uncertainty are interpolated (bilinearly) to a common 10 km × 10 km grid in polar-stereographic projection (central latitude 71◦ S; central longitude 0◦ W; origin at the South Pole; WGS-84 reference ellipsoid)
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