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To fully exploit data from the Gravity Recovery and Climate Experiment (GRACE), we separate geophysical signals observed by GRACE in Antarctica by deriving high-spatial resolution maps for present-day glacial isostatic adjustment (GIA) and ice-mass changes with the least possible noise level. For this, we simultaneously (i) improve the postprocessing of gravity data and (ii) consistently combine them with high-resolution data from Ice Cloud and land Elevation Satellite altimeter (ICESat) and Regional Atmospheric Climate Model 2.3 (RACMO). We use GPS observations to discriminate between various candidate spatial patterns of vertical motions caused by GIA. The ICESat-RACMO combination determines the spatial resolution of estimated ice-mass changes. The results suggest the capability of the developed approach to retrieve the complex spatial pattern of present-day GIA, such as a pronounced subsidence in the proximity of the Kamb Ice Stream and pronounced uplift in the Amundsen Sea Sector.

Plain Language Summary The Gravity Recovery and Climate Experiment (GRACE) satellite mission has become an indispensable tool in monitoring global mass variations. However, the limited horizontal and lacking vertical resolution of the gravity satellite data is still a major challenge. We develop an approach that allows gravity satellite data to be consistently combined with other complementary data that feature higher spatial resolution (e.g., altimetry and climate data). The consistent combination in terms of horizontal resolution allows the different signals contributing to the total GRACE signal to be accurately separated. We demonstrate the utility of the developed approach by separating present-day ice-mass changes and glacial isostatic adjustment (GIA) in Antarctica using gravimetry, altimetry, climate, and GPS data. For the first time, our data-driven approach allows the statistically significant small-scale GIA features to be retrieved, such as a pronounced subsidence in the proximity of the Kamb Ice Stream. The estimated GIA is important to validate geophysical GIA models, while accurately estimated Antarctic ice-mass changes are important for sea-level projections. Moreover, the developed method can be applied on data derived from, for example, the upcoming satellite altimetry and gravity missions and in any other application which involves GRACE data and any other geodetic data.