Precision of Bottom Loss Predictions from a Physical Sediment Model

摘要

Bottom loss (BL) can be computed from profiles of the geoacoustic parameters density, compressional speed and compressional attenuation. The geoacoustic properties can be derived from physical properties of the sediments, which are more readily available, using a physical sediment model (PHYSED) based on the Biot theory of acoustic propagation in porous media. We predict BL for sediments on the continental terrace and evaluate those predictions in terms of their precision. We use readily available physical properties assembled into the data base PHYROSE, with the PHYSED model to produce geoacoustic profiles for the calculation of BL by the computer program REFLEC. We divide continental terrace sediments into provinces based on water depth ranges and grain size classes. We find that useful separations of BL values by province do occur. Some provinces show significantly different mean BL values and some provinces show significantly reduced variences. This result has particular importance in the show significantly reduced variences. This result has particular importance in the shallow water jenvironment, since sediment physical properties are often the only readily obtainable information describing the seafloor. We strongly recommend the application of this physical sediment approach in shallow water to further the development of seafloor interaction models and data bases sutiable for operational use.