Comparison of observed and predicted reflection loss in the Beaufort Sea using a multilayer, rough, acousto-elastic reflection coefficient model

The Canada Basin Acoustic Propagation Experiment (CANAPE) conducted during 2016–2017 utilized a 150-km radius, seven-mooring acoustic tomography array to examine acoustic propagation in the new Arctic. Broadband acoustic transmissions with center frequencies of 172.5, 250–255, and 275 Hz revealed identifiable and trackable ray-like arrivals with grazing angles of 10–20 degrees that reflect off the ice 3–10 times. Worcester et al. (2024) [J. Acoust. Soc. Am. 156, 4181–4192] showed that the maximum excess transmission loss per surface reflection, defined as the increase in transmission loss relative to open water conditions, varies from 2–6 dB and is strongly frequency and angle dependent. The loss scales roughly with ice thickness. We have developed a four-layer (water, skeletal ice, solid ice, and air), acousto-elastic reflection loss model that incorporates roughness using the Rayleigh formula. When combined with in-situ observations of ice thickness and roughness, as well as physical parameters for ice from literature, the model shows good agreement with the observations during the maximum ice thickness period in June. Comparisons will be made for the ice growth and melting phases, sensitivity to ice parameters will be investigated, and the results will be interpreted in terms of first year ice rheology.