Acoustic backscattering from a fine sand seabed at 12–24 kHz in the South Yellow Sea of China

Seabed acoustic backscattering measurements were conducted at a shallow water site in the South Yellow Sea of China. The acoustic backscattering strengths from a fine sand seabed were obtained in a wide range of grazing angles (26°-60°) at 12-24 kHz. Backscattering strengths exhibited frequency and grazing angle dependence, which increases with increasing frequency and grazing angle. The predictions of the scattering model, based on the effective fluid density model, whose input parameters were obtained via measurements or acoustic inversions, were compared with the measured data. The scattering model predictions agreed well with the measured data across all of the investigated frequencies and grazing angles. The comparisons show that rough surface scattering plays the leading role within the 26°-60° grazing angle range at 12 kHz in fine sand sediments. When the frequency exceeds 16 kHz, sediment volume scattering becomes the primary mechanism of seabed acoustic scattering in a broader range of grazing angles as the frequency increases. Moreover, a transition in the scattering mechanism was noted in a specific grazing angle range as the frequency increased from 12 to 16 kHz.