Seamounts, Direct Blast and Volume Reverberation Upgrades

Abstract : This document describes upgrades made to the SAIC Active System Model (SASM). Major enhancements include seamount echos, direct blast and volume reverberation along with enhanced plot capabilities. The SASM is a long range bistatic prediction model which estimates system performance for large ocean areas that are within 500 nm of the receiver. In order to efficiently compute long range system performance, relatively coarse angular and range step sampling is used. While this sampling is used to compute the large scale acoustic variations, a higher resolution method is employed to model the discrete returns from seamounts and direct blast arrivals. A pattern recognition algorithm determines the position, height and other parameters for each seamount. Once located, the seamounts are removed from the bathymetry data and modeled ad discrete features in both the REVERB and SYSMOD modules. Addition of seamounts, direct blast and volume reverberation has made version 1.3 a model which simulates discrete arrivals while efficiently computing system performance over large areas. Transmission loss; Volume scattering depth.