Spatial and temporal variability of Cross-Basin acoustic ray paths
Ort, Coenraad Marinus
Sentner, Albert J., Jr.
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It was suggested by Munk and Forbes (1989) that climate induced changes in ocean temperature may be monitored by measurements of cross-basin acoustic travel time variability. The feasibility of such a monitoring system depends on the spatial and temporal variability of the cross-basin acoustic paths in the presence of ocean variability of many different scales. For this thesis the variations in arrival position, azimuthal arrival angle, ray trajectory and the corresponding changes in travel times along the three- dimensional multipaths due to meso- and gyre scale ocean temperature fluctuations were analyzed. Emphasis was placed on the acoustic paths from Heard Island in the Indian Ocean, the proposed location for the sound source, to the west coast of the United States. An optimal receiver site location was found to exist in the vicinity of Monterey Bay, California. The possibility of a proposed listening site location near Coos Bay, Oregon, was also examined. However, the ray paths to Coos Bay interact with the bottom frequently, thus rendering them less reliable. All the ray traces for this study were carried out using the recently upgraded Hamiltonian raytracing code HARPO, interfaced with output form the Semtner-Chervin eddy resolving global ocean general circulation model. This interface allows for a realistic simulation of the effects of meso- and gyre scale processes on the variability of the various cross-basin paths.
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