Spatially resolved GIA in Antarctica from a global inversion

The mass balance of the Antarctic Ice Sheet (AIS) can be obtained from time-variable gravity fields from GRACE and GRACE-FO. This is useful to investigate the ice sheet's adaption to a changing climate and its contribution to the global mean sea level. However, the correction for the present-day glacial isostatic adjustment (GIA) in Antarctica is still the largest uncertainty contributor in gravimetric mass balances. Lacks of knowledge of the ice loading history and the solid Earth's rheology lead to a large spread of GIA predictions from forward modelling approaches. We developed a method (Willen et al. 2022, https://doi.org/10.1007/s00190-022-01651-8) that allows to spatially resolve GIA, ice mass changes, and firn thickness changes in Antarctica within a globally consistent framework using geodetic satellite data and results of climate modelling. From simulation experiments, we found that the signal separation is possible despite data limitations as long as accounting for spatial error covariances of the input data sets. Here, we present and discuss results from a global inversion of satellite gravimetry data (from GRACE/GRACE-FO), satellite altimetry data (CryoSat-2), regional climate modelling (from RACMO2), and modelled firn thickness changes (from IMAU-FDM) over the time period Nov 2010 to Dec 2020. Furthermore, we will discuss the advantage of implementing this methodology in a global sea level inversion framework.
The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)