Leveraging Satellite Altimetry and Gravimetry for High-Resolution Antarctic Mass Change

Abstract

Satellite altimetry missions have transformed our capability to observe ice sheet surface elevation change with unprecedented spatial precision. While altimetry excels at localized surface height changes, converting height to mass requires firn air content corrections. Conversely, satellite gravimetry (GRACE/GRACE-FO) directly measures mass change with high accuracy over large scales, but is limited to coarse spatial resolutions (~300 km).Here, we present a formal data combination framework integrating two decades (2002–2020) of satellite altimetry observations (ICESat, ICESat-2, CryoSat-2, Envisat, ERS-2) with GRACE/GRACE-FO Level-1 data at the level of the gravimetry normal equations. By solving for 1 degree circular disk mascon elements, altimetry observations dominate the inversion at individual mascon scales, breaking inter-mascon spatial correlations and localizing signals over dynamic glacier catchments like Pine Island, Thwaites, and Totten Glaciers. Gravimetry dominates at long spatial wavelengths, preserving continental and basin-scale mass balance accuracy.The monthly Antarctic mass change solution achieves an effective spatial resolution of (100 km)2 , fulfilling long-standing community target requirements. Applying mass-conserving gain factors derived from altimetry spatial fields further yields downscaled monthly mass change at a 1.92 km scale. Rigorous propagation of stochastic measurement errors and systematic model uncertainties (GIA, firn air content) is included.This joint inversion highlights the value of multi-sensor Earth data fusion, offering a data processing blueprint to ingest observations from future satellite altimetry missions CRISTAL and EDGE, and satellite gravimetry missions GRACE-C and NGGM.