Physical Insights Into The Navy Standard Low Frequency Bottom Loss (LFBL) Data Base

Acoustic bottom properties are described in terms of bottom loss versus grazing angle using the Navy standard sediment thickness data base and the ten parameter low frequency bottom loss (LmL) geoacoustic data base. Physical insight into the characteristics of these bottom loss curves is discussed in this paper. horizontal range is summed together to calculate the bottom loss. This bottom loss is assigned to the grazing angle associated with the water-sediment reflected path for that range. In the January 1992 version off the model the horizontal range is dependent on the water depth. The water-sediment reflection coefficient for a stratified media as derived by Tolstay and Clay (5) is used because of the presence of the thin layer. When the thin layer density is equal to the sediment density, the presence of the thin layer is effectively removed. In the absence of the thin layer the reflection coefficient reduces to the familiar Rayleigh reflection coefficient.