Estimating Geoacoustic Properties of Surficial Sediments in the North Mien-Hua Canyon Region With a Chirp Sonar Profiler

Acoustic reflection coefficients and attenuation rolloff rates of the seabed near North Mien-Hua Canyon, northeast of Taiwan, were measured from chirp sonar echoes during the Quantifying, Predicting, and Exploiting (QPE) Uncertainty Initiative Experiment in 2009. Using these measurements and the Biot theory with a fluid approximation, the depth-averaged sound speed, density, and medium attenuation of the surficial sediment layer were estimated. The sediment types in the chirp sonar survey area vary from fine sand to coarse silt. To capture this spatial variability, the 1-D geoacoustic parameter estimates along the chirp sonar track were interpolated onto a 2-D grid using an objective mapping technique. The 2-D maps of surficial sediment properties, along with interpolation errors, can be further applied to underwater sound propagation models in the experimental area.