Cryoacoustic inversion for Beaufort Sea ice properties during 2016–2017 using a rough, layered 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 changing 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 11°–19° that reflect off the ice 3–10 times. Worcester etal. (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. A four-layer (water, skeletal ice, solid ice, air), acousto-elastic, plane-wave reflection loss model that yields loss predictions in line with the results of Worcester et al. (2024) using the observed ice draft and ice parameters from the literature is used here in a cryoacoustic, Bayesian inversion to predict the time evolving ice properties over an annual cycle. The model incorporates roughness using the Rayleigh formula. Challenges include nonlinearity, missing physics, and questions of how well the data constrains the model.