Abstract:

Shallow-water broadband propagation modeling and time-series simulation was done for representative ocean environments. Simulations of two-way temporal signal dispersion for both time-forward and time-reversed transmissions are presented. The modeling effort used the OASES and ORCA models to simulate acoustic conditions from horizontal line arrays and omnidirectional sources in the 30 to 600-Hz frequency region. Two-way predictions are presented and compared to data results for several representative cases. Some sets of signals were time reversed and back propagated through several perturbations of selected experimental conditions to quantify signal decorrelation effects due to the environment. Additionally, the effects of water depth on pulse shape and spread are demonstrated for two hypothetical shallow-water cases. Comparisons with one-way time series measured during the Celtic Duet sea trial conducted off the Southwest Approaches in July 1992 are discussed. Results for one-way modeling in one hypothetical case for a sandy bottom show pulse spreads gradually increasing up to 2 s as depth is varied from 50 to 350 m and ranges are increased out to 18 km. [Work supported by ONR and NAWC.]