Bottom Contour Influence on Ray Tracing
1991
Unger, Shaari M.
The objective of this paper is to qualitatively determine the effect changes in bottom contour will have on sound propagation using ray trace techniques. This study describes some bathymetric properties of the Nanoose Bay range. It outlines the Hamiltonian Acoustic Ray Tracing Program for the Ocean (HARPO), a ray theory based model, and discuss the relationship between ray tracing and transmission loss. HARPO ray traces are used to portray the changes in the propagation of sound as changes in bottom contour are introduced. Previously used ray trace models have assumed flat bottom boundary conditions. This qualitative study shows the impact of modeling bottom contour irregularities on the predictability of sound rays and thus on transmission loss. The HARPO ray trace model is presented, and qualitative results are examined between several bottom contour variations. The effects of changes in bottom contour are assessed. These irregularities caused changes in attenuation, path length and angles of incidence. Results of a study which measured in-situ data from three equally spaced receivers are also discussed. Acoustic receive levels were comparable. Test suggestions are proposed for obtaining quantitative transmission loss values.
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