Inverting for source location and internal wave strength using long range ocean acoustic signals

It is known that internal waves cause significant scattering of acoustic signals in ocean propagation. The purpose of this research is to extract relevant information about the source location and, if possible, do a simple inversion for the effective average internal wave strength of the ocean. The Frequency Interpolation Parabolic Equation (FI-PE) is developed to increase speed of forward calculations range dependent environments. Using the FI-PE and an internal wave generating algorithm, an ensemble of forward simulations at various ranges and internal wave strengths were computed.; Data from three long range propagation experiments has been used: The Acoustic Engineering Test (WET), ATOC95, and Alternate Source Test (AST). Due to failure of the upper half of the array on the AET experiment a method was derived for extracting acoustic mode information from a small (20 element) array in deep water (with 100 propagating modes). With 40 elements in the ATOC95 and AST experiments, the standard Least Squares mode projection was used to extract the mode information of the data.; A study of the loss of coherent acoustic energy due to internal wave scattering reveals that coherent Matched-Field Processing should be possible at ranges of 500 km at 75 Hz and 3000 km at 28 Hz. Several matched field beamformers are introduced and their mode space analogues are derived. Results are presented from simulations with internal waves and from two experiments. Mode statistics based (incoherent) algorithms are developed and applied to the data. A mode spectrum filter successfully locates the depth of the AET source. Range estimators using the arrival pattern of wavefronts and the relative arrival times of modes are presented.; With a set of simulations through various strength internal wave fields, an understanding of the affects of internal waves on mode spread and bias can be achieved. An inversion using the spread of the mode arrivals is done on the ATOC95 data and an average internal-wave strength of 1.91 GM is found. The mode statistics are parametrized as a function of strength and range. This parametrization permits a simultaneous inversion for source range and internal-wave strength.