LONG-TERM GOALS

Sound propagation in the areas of continental shelves is complicated due to many three-dimensional (3-D) oceanographic and marine geologic features, such as shelfbreak frontal systems, nonlinear internal gravity waves and topographic variability. The long-term goals of this project are targeted on understanding the 3-D sound propagation effects caused by these environmental factors, and also on applying the 3-D sound propagation physics to acoustic inversions. OBJECTIVES Due to the horizontal inhomogeneity in the water column caused by shelfbreak frontal systems, nonlinear internal gravity waves and other physical oceanographic processes, horizontal refraction of sound occurs and produces significant 3-D acoustic propagation conditions. One of the objectives of this project is to develop an efficient and accurate 3-D sound propagation model (both theoretical and numerical models) for applications related to low-frequency sonar systems. In addition to the 3-D sound propagation study, this project also has the investigation on the feasibility of two specific inversion techniques in the area of continental slopes: (a) source localization and (b) bottom geoacoustic inversions. This work requires a solid understanding on 3-D sound propagation, and it is closely connected to the first topic