Antarctic glacial-isostatic adjustment from GRACE and numerical modelling: GFZ

Antarctic glacial-isostatic adjustment from GRACE and numerical modelling

"Improved ice-mass balance and GIA-induced sea-level change by assimilation of GRACE and SLI data to 3D viscoelastic earth model and joint gravity field inversion“

Uplift rates (mm/a) presently available for POLENET survey stations in West Antarctica. Blue and green contours indicate the GIA predictions. Predicted elastic uplift rates (mm/a) are shown in brackets (Bevis et al. 2009, doi: 10.1029/2009GC002642) *(Sasgen)*

Duration: 2009 - 2013

AGIA is a project in a DFG Priority Programme SPP1257: "Mass transport and mass distribution in the Earth system".

The Antarctic Ice Sheet (AIS) is an important component of the Earth’s climate system. The knowledge of its current state and near-future evolution contributes to the reliability of climate models and, in particular, provides an estimate of global temperature and sea-level changes for the next decades. The mass balance of the AIS is an indicator of its current state. The Gravity Recovery and Climate Experiment (GRACE) satellite mission monitoring temporal variations of the gravity field due to mass changes in the Earth’s interior and on its surface offers an unprecedented accuracy to monitor the AIS’s mass balance. However, the GRACE data are contaminated by the mass redistribution in the Earth’s mantle due to glacial-isostatic adjustment (GIA).

Rate of geoid-height change over North America. — Rate of geoid-height change over North America from GRACE (left) and model adjusted to the GRACE observation (right) including GIA and present-day ice-mass changes (contribution to SPP1257 special issue planned). *(sasgen)*

This project constrains the AIS’s past changes inducing GIA and its present-day mass balance by a joint inversion of the GRACE data for Antarctica using a three-dimensional viscoelastic earth model. To achieve this, the adjoint method is adapted to the numerical description of the viscoelastic earth model. This will allow the assimilation of sea-level indicators for the past 10,000 years. The results of the project will provide an improved GIA model for Antarctica and a more accurate estimate of the AIS’s mass balance and its contribution to global sea-level change.