Improving the Physics of Applied Reverberation Models

The proposed effort will enhance the capability of the Acoustic System Performance Model (ASPM) and its implementation of the ASEPS Transmission Loss (ASTRAL) model by adding to it a treatment of several physical phenomena. Research in recent years has demonstrated that sea surface forward scatter consists of coherent and incoherent components with both having profound impact on reverberation. The TOTLOS model has been developed to account for these, with recent improvements to allow for a wide range of sediment speeds and account for more general surface roughness spectra. In addition, previous integration of low-frequency bottom loss algorithms within ASPM will be investigated for expansion to substantially higher frequencies to provide more realistic bottom characterization. Refinements will also be made to further simplify the code base of ASPM with a goal of speed improvement. Modeling improvements will be validated with measured data sets and environmental inputs from the Office of Naval Research Target and Reverberation Experiment (TREX13) project. Documentation will be developed to support ASPM approval through the Oceanographic and Atmospheric Master Library (OAML) process. Preliminary integration will be performed using research and development mission planning software for multistatic active sonobuoy systems.