Model Results of the Effects of Internal Waves on Acoustic Propagation.
Abstract
A model has been developed which simulates time variations in Acoustic transmission induced by internal wave activity in the ocean. The model produces explicit sample time series of acoustic transmission parameters. An explicit objective of the work was to provide a mechanism for investigating how such fluctuations affect low frequency sonar performance. The model parameterizes the internal wave field according to a power spectrum proposed by Garrett and M nk, and unperturbed acoustic transmission through use of ray trace techniques. The interaction between the two considers the effect on the phase of individual ray paths, and consequent fluctuations in the multipath sum. Both the ray trace characteristics and some parameters of the internal wave field depend on environmental conditions, so that the model can investigate sensitivity of results to geographic location and season. Sample model results show a strong increase in fluctuation rates with increasing acoustic frequency, a fluctuation magnitude (one standard deviation) of 5 to 6 dB except, perhaps, at short range, and no strong dependence on geographic location. One direct comparison of model results with experimental fluctuation data was made, and the results are considered very satisfactory. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 03, 1978
- Accession Number
- ADA057333
Entities
People
- E. Moses
- W. Galati
- W. Nicholas