Airborne radar radiometry and coastline mapping of the highly-specular subglacial terrain on Devon island

The highly-specular terrain present under Devon Ice Cap in the Canadian Arctic Archipelago has been the target of several multi-instrument investigation campaigns. Initial analysis of radar sounder data collected by the High Capability Radar Sounder (HiCARS) and the Multichannel Coherent Radar Depth Sounder (McCORDS) over the area using state-of-the-art quantitative methods suggested the terrain could be a hypersaline lake [Rutishauser et al., Science Advances, 2018], however, newer seismic and conductivity measurements suggest a rigid, electrically insulating material that is incompatible with liquid water [Killingbeck et al., AGU, 2022]. Starting from the hypothesis that the highly specular terrain consists of flat and smooth sediments originating from a paleolake, we propose to revisit the original radar data and to apply more advanced dielectric and subsurface rough scattering hypotheses in order to constrain the materials present in the subsurface. We also propose to use subsurface interferometric clutter discrimination [Scanlan et al., 2020, Annals of Glaciology] on Multifrequency Airborne Radar-sounder for Full-phase Assessment (MARFA) data to map the coastline of the supposed paleolake. Combining dielectric and subsurface topographic information with modeling of the thermophysical evolution of the lake over interglacial cycles could reveal the history of the formation of the structure. Preliminary work on the new radar data analysis is presented.