Estimation of a sediment attenuation coefficient using mid-frequency bottom-interacting signals in Jinhae Bay, Southeast Korea

Abstract

The inversion results of geoacoustic parameters using bottom-interacting signals in Jinhae Bay, South Korea, were presented in March 2019 by Kwon, Choi, Ryang, Son, and Jung [J. Acoust. Soc. Am. 145, 1205–1211 (2019)]. At site 1 in this study area, where the surficial sediment was dominated by mud, bottom-loss estimates were typical of losses in sediment with a sound speed lower than that of the water column. In this case, because most of the energy incident on the bottom at the angle of intromission is transmitted into the sediment, scattering may dominate the bottom-path energy, which can lead to an underestimate of bottom loss and an overestimate of the sediment attenuation coefficient. Here, we attempt to provide an accurate estimate of the sediment attenuation coefficient by comparing the difference in amplitudes between the bottom-reflected and sub-bottom-reflected signals over a frequency band of several kHz. To verify the inversion results, measurements of sediment attenuation at the site were also taken by repeatedly transmitting and receiving continuous acoustic waves of 120–180 kHz using four stake transducers embedded in the sediment. The inversion results are in reasonable agreement with the sediment attenuation coefficients measured in situ.