Mapping the Evolution of Antarctica's Mass Balance in Space and Time

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1245788/SimonsThis award supports a project to undertake an accurate and robust spatial and temporal assessment of the mass flux in the Antarctic region from the data collected by the GRACE satellites. Using a technique developed during work on the Greenland ice sheet, the work will significantly improve on prior ice mass estimates made from public global "Level 2" GRACE data. More raw "Level 1" data will then be used to perform new localized inversions for Antarctic mass changes. These improved estimates will then be used to study the laterally varying viscosity structure in the mantle beneath Antarctica to correctly attribute the observed secular mass change to ice gains and losses by making the appropriate corrections for ongoing post-glacial rebound. While the GRACE mission has mapped Earth?s gravity field since 2002, there is still significant scientific disagreement as to how much terrestrial ice mass has changed, where it has changed, and by how much ice loss may have been accelerating. This disagreement partly stems from the choices made by different groups in their data processing procedures. The precise nature of the assumed error structure and the choice of noise reduction technique limit the spatial and temporal resolution of GRACE results. The intellectual merit of the work is that it will strive to result in the most accurate and best resolved estimate of the ice mass changes in Antarctica using gravimetry, and will be easily related to estimates from other measurement techniques. By comparing the estimates from gravimetry with other measurements from laser altimetry, InSAR, GPS, and surface mass balance studies, better constraints on forecasts of future sea level rise will be possible. The results of this work will be of great interest to the geodetic and GRACE community as well as those who work on Antarctic ice sheet mass balance. The broader impacts of the work are that it will help inform the community and the public about the uncertainty of climate-related measurements such as GRACE gravimetry, while at the same time explaining the serious threat of climate change suggested by these measurements. Results will be published in peer-reviewed journals and all processing software tools will be made freely available to others. Results will also be made available in a format that is useable by the general public to get informed about the world's changing ice sheets. This work will provide data for undergraduate research projects and as part of this project an undergraduate student will be mentored. This project does not require field work in the Antarctic.