Walking on snow-covered Arctic sea ice to infer ice thickness

Abstract

The ice-covered Arctic Ocean constitutes a unique underwater acoustic waveguide; it is a half-channel, upward refracting environment possessing a rough upper boundary consisting of sea ice of varying thickness. The sea ice itself is an acoustic waveguide, capable of supporting the propagation of compressional and shear waves. In particular, the ice supports compressional wave resonances created by impulsive forces on the upper surface of the ice. During ICEX20 and ICEX22, observations were made of compressional wave resonances excited by hammer drops, as well as by near-impulsive signals generated from the compression of dry snow underfoot while walking on the ice. Results demonstrate that ice thickness can be inferred from compressional wave resonances in the sea ice waveguide using signals generated by walking on the snow-covered ice. Inferred ice thickness estimates were consistent with observations made by magnetic induction and physical measurements in holes drilled through the ice. Average first- and multi-year ice thicknesses were inferred to be 1.1–1.3 m and 2.4–2.5 m, respectively.