Improving the Physics of Applied Reverberation Models

We propose to enhance the capability of ASTRAL/ASPM by adding to it a treatment of several physical phenomena. Several methods enabling these new features have been developed and tested in recent years and are mature enough for transition. Efforts will be made to ensure the enhancement will not come with significant loss of efficiency. The Phase I effort consists of incorporating into ASTRAL/ASPM the surface loss model TOTLOS, which takes into account surface forward scattering in its effect on both propagation and reverberation. A Phase I Option is also proposed and consists of developing a strategy for incorporating more physically-based bottom loss models into ASPM reverberation modeling, testing the strategy for a specific environment, and comparing the results to the current bottom loss models used in ASPM as well as parabolic equation and mode codes. Potential Phase II efforts include: (a) incorporate tested models, where appropriate, into ASPM; (b) use ONR TREX13 data sets along with full environmental inputs, to evaluate the improved version of ASTRAL/ASPM, and demonstrate its efficacy; (c) test the resulting code on other data sets, including those of NAVO; (d) help guide the ASPM enhancements through the OAML process.