Acoustic fluctuations due to shallow thermal microstructure

Loading...
Thumbnail Image
Authors
Hagen, James Burgess
Subjects
Acoustic fluctuations
Thermal microstructure
Shallow water thermal microstructure
Advisors
Thornton, Edward B.
Date of Issue
1974-12
Date
December 1974
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
Simultaneous measurements of waves, orthogonal water particle velocities, temperature, conductivity and acoustic phase and amplitude measurements at 20 and 40 kHz over horizontal and vertical, 2m paths were made at the NUC oceanographic tower, San Diego in April 1974. Four stochastic models for acoustic propagation including geometric, Born, Rytov and Debye approximation models were tested. The Krosil'nikov - Obhukov formulation of the Born approximation yielded reasonable results. Difficulty in establishing scales obviated good results from the Rytov and Debye models. Taylor thermal microscales from spatial correlation analyses determined vertically across the thermocline varied from 6.8 to 178 cm. The measured variance of the index of refraction ranged from 4.5x10-4 to 2.7xl0-3. Temporal stochastic analyses showed horizontal acoustic path losses were ten times vertical losses because of diffraction effects. The primary mechanisms for acoustic variability were internal and surface waves pumping the thermocline up and down.
Type
Thesis
Description
Series/Report No
Department
Oceanography
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
Funder
Format
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.
Collections