Geophysics PhD Defense, Danny May: "Exploration Geophysics-Inspired Acquisition and Analysis for Ice-Penetrating Radar"

Radio-echo sounding of ice sheets provides key constraints on englacial and subglacial material and thermal conditions. However, standard survey configurations have made it difficult to unambiguously resolve properties such as fine-scale bed geometry, ice temperature, and subglacial hydrological conditions and to monitor how these properties evolve over time. This work presents a set of low-cost modifications to existing radar systems (using radio frequency-over-fiber) that help address these limitations by enabling larger distributed antenna arrays and greater sensor separations than are conventionally possible.

Results are presented from several field deployments illustrating the range of applications this enables. A large imaging array deployed on a polythermal glacier in Svalbard resolves the ice-bed interface with much improved resolution compared to standard stationary configurations. Polarimetric surveys collected at large offsets in Antarctica probe englacial dielectric and thermal structure. Finally, survey geometries adapted from exploration seismology, including a towed antenna array, a borehole sensor, and a stationary array operated over multiple days, were deployed on a temperate glacier in Alaska to recover near-surface properties and their evolution over time. Together, these results improve the ability to constrain material properties and monitor glacier processes over time, forming the foundation for 3D time-lapse imaging of ice sheet structure.