Ice-Mass Changes Inferred from Global and Regional GRACE Solutions

Abstract:

Since 2002 the Gravity Recovery And Climate Experiment (GRACE) mission has been measuring temporal variations of Earth's gravity field with unprecedented accuracy. This data set provides valuable information on the distribution and variation of mass in the Earth's subsystems such as atmosphere, hydrosphere, ocean and cryosphere. Reprocessed GRACE time-series of monthly gravity field spherical harmonic solutions generated at GFZ (RL05a) show significantly less noise and spurious artifacts. In addition, a regional method based on radial base functions that is capable to compute models in regional and global representation has been developed. This new method localizes the gravity observation to the closest regions and omits spatial correlations with farther regions. The present study makes use of both solutions in order to quantify recent ice-mass changes and their contribution to global sea-level rise. We further compare the ice-induced crustal deformations due to the dynamic (un-)loading of the crustal layer with GPS uplift measurements along Greenland's coastline. Mass/Volume changes derived from ICESat laser altimetry measurements both in Greenland and Antarctica are used to validate the GRACE results.