Inversion of surficial sediment thickness from under-ice acoustic transmission measurement

Abstract

The under-ice acoustic transmission experiment of 2013, conducted under ice cover in the Fram Strait, was analyzed for bottom interactions for the purpose of developing a model of the seabed. Using the acoustic signals, as well as data from other sources, including cores, gravimetric, refraction, and seismic surveys, it was deduced that the seabed may be modeled as a thin surficial layer overlaid on a deeper sediment. The modeling was based on the Biot–Stoll model for acoustic propagation in porous sediments, aided by more recent developments that improve parameter estimation and depth dependence due to consolidation. At every stage, elastic and fluid approximations were explored to simplify the model and improve computational efficiency. It was found the surficial layer could be approximated as a fluid, but the deeper sediment required an elastic model. The full Biot–Stoll model, while instrumental in guiding the model construction, was not needed for the final computation. The model could be made to agree with the measurements by adjusting the surficial layer thickness.

An Ocean Acoustic Modeling Based on the Physical Parameters Clustering of the Arctic Ice Floes: Applied to the Study of Acoustic Field Response as Ice Floes Thickness Varies

“…The acoustic signal was received 32 km away from the source by four vertical array hydrophones with the depth of 15, 20, 25, and 30 m, respectively. Meanwhile, scientists used the OASES (Schmidt, 2011) software to build an acoustic propagation model with a horizontally layered waveguide and compared the modeling result with the measured data (Chotiros et al., 2021).…”

“…In the FEM‐O model, the ice is modeled as an elastic layer with average thickness, density, p‐wave speed, s‐wave speeds, 2 m, 900 kg/m 3 , 3,600 m/s, and 1,800 m/s, respectively (Chotiros et al., 2021). In the FEM‐C model, a surface with a roughness of 0.1954 m (Table 3) satisfying with Gaussian distribution $$f(x)$$ is established.…”

“…Moreover, some scholars (Lee et al., 2019; Sagen et al., 2008) have designed continuous observation systems under the sea ice to cope with dynamic environments. Recently, acoustic model calculations and experimental verifications related to ice floes were separately carried out by Simon and Chotiros (Chotiros et al., 2021; Simon et al., 2018). However, the acoustic field takes ice floes as one or more acoustic reflection layers, which could not be equally crucial microstructure parameters due to the lack of investigation data.…”