Mapping the Antarctic Basal Ice Unit Using Ice-Penetrating Radar Data Archives

The Antarctic Ice Sheet is a major source of uncertainty in future sea-level rise, yet its internal structure remains poorly understood. In many regions, radar sounding reveals a distinct layer in the deepest portion of the ice sheet, immediately above the bed. Unlike the overlying ice, this layer lacks visible internal reflections. This “basal ice unit” may form through intense deformation, elevated temperatures, or refreezing of subglacial water, and its behavior may affect both ice flow and the preservation of exceptionally old ice. This project will investigate the processes and conditions that govern the formation and evolution of the basal ice unit. It will also expand the open-source QIceRadar platform, enabling researchers to more easily interpret, compare, share, and reuse Antarctic radar data. These advances will lower barriers to polar research, support reproducible science, and provide undergraduate training in geospatial analysis, scientific programming, and Antarctic geophysics. The project will address two questions: what causes the loss of traceable englacial reflections within the basal ice unit, and how does this unit deform relative to the overlying stratigraphic ice? The team will examine basal ice unit thickness across Antarctic ice-penetrating radar datasets. Measurements from radar systems with different center frequencies will be compared at survey intersections to assess the effects of vertical resolution and signal attenuation. Thickness patterns will also be evaluated against ice-flow conditions, subglacial topography and roughness, geothermal setting, subglacial hydrology, and geology to test competing formation hypotheses. In parallel, QIceRadar will be enhanced with georeferenced delineation tools and standardized data formats that enable researchers to share and reuse their delineations across the community. Ice-flow models constrained by englacial radiostratigraphy will also be applied in selected regions of interest to constrain basal melting and freezing rates and basal ice rheology. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.