LONG-TERM GOAL

The long-term goal of this research is to develop our understanding of long-range oceanic pulse propagation through random sound speed fields, like those caused by internal waves, so that we can use acoustic fluctuations like temporal, vertical, and horizontal coherence to infer average internal-wave spectral parameters. OBJECTIVES The scientific objective of this work is to develop analytical expressions for temporal, vertical, and horizontal coherence of the acoustic field as a function of internal-wave model parameters. Analytical results for these second moments are important because they eliminate the need for time-consuming Monte-Carlo runs and they allow an efficient treatment of the inverse problem[3]. A key element of this work is understanding the limits of geometrical optics (GO) at frequencies of order 75-Hz. It has been shown that acoustic fluctuations from energy which has ensonified the upper few hundred meters of the ocean cannot be explained using the Garrett-Munk (GM) internal wave model[3], so a secondary, oceanographic objective of this work is to explore upper ocean internal-wave models