Projects
CitcomSVE
This project focuses on advancing solid-Earth and ice sheet modeling for the benefit of satellite gravimetry, altimetry, and InSAR observations by leveraging the capabilities of both the Ice-sheet and Sea-level System Model (ISSM) and the glacial isostatic adjustment (GIA) code CitcomSVE. This work grew out of a collaboration between the Jet Propulsion Laboratory and Caltech, with contributions from team members at the University of Colorado, Boulder. Our primary objective is to explore the influence of laterally heterogeneous (3D) Earth viscosity structure on the signal of GIA in geodetic datasets, specifically the GIA correction used in the construction of level-3 GRACE(-FO) data, and on ice-sheet evolution via a coupling framework between CitcomSVE and ISSM. Both CitcomSVE and ISSM are open source, documented, and actively contributed to by members of the cryospheric and solid-Earth science communities.
Reliable sea-level rise projections and inference of surface water mass balance rely on understanding ice-sheet-solid-Earth interactions over different timescales. Traditional GIA models, including those currently employed to remove the GIA signal from GRACE(-FO), utilize a 1D radially symmetric Earth viscosity model that is increasingly at odds with the strong lateral heterogeneities in Earth structure observed in seismic tomography. With CitcomSVE, we compute GIA models with predictions of present-day vertical land motion (VLM), change in gravity and equivalent water height (EWH), and relative sea level (RSL) using both fully 3D and 1D viscosity structures. We explore how lateral heterogeneity influences the spatial pattern and amplitude of GIA both globally and in key regions of interest, such as West Antarctica, Greenland, and the North Atlantic. We aim to determine both the optimal 3D Earth structure and ice history that fit both present-day geodetic observations and paleo-sea-level data. A more realistic GIA correction for GRACE(-FO) based on a 3D Earth model has the potential to alter interpretations of surface water mass changes drawn from satellite gravimetry data.
3D Earth viscosity structure can also directly affect ice-sheet evolution, even on shorter timescales. We are developing a coupling framework between CitcomSVE and ISSM to accurately account for the effects of 3D viscosity in the ice-sheet model. This coupling interfaces ISSM’s surface mass transport capabilities (e.g. ice flow, terrestrial and subglacial hydrology, and ocean bottom pressure models) with CitcomSVE’s 3D solid-Earth deformation capabilities. These efforts leverage state-of-the-art technologies like finite-element modeling, parallel computing, data assimilation, and uncertainty quantification to facilitate a better understanding of ice-sheet-solid-Earth interactions and the influence of GIA on contemporary ice mass loss, ice-sheet evolution, and sea level rise.
