Amplitude and time fluctuations and their relationship to temperature variations

• Published in: The Journal of the Acoustical Society of America 2003-04, Vol.113 (4_Supplement), p.2333-2333
• Main Authors: Lutz, Steven D., Culver, R. Lee, Bradley, David L.
• Format: Article
• Language: English
• Subjects: Marine
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.4780857

Amplitude and time fluctuations of direct and refracted paths measured during a field test near San Clemente Island in August 2002 are presented. Signals used include 20 and 40 kHz CW pulses with 0.14 ms and 1.0 ms durations. The transmitters were suspended from a buoy with a bungee section in the mooring to minimize the watch circle. The receive hydrophone array was suspended from a research vessel in a three point moor. The source to receiver separation was 714 m. Towed CTD data, also collected during the experiment, is presented. A relationship between the amplitude and phase fluctuation in the acoustic arrivals and temperature variations in the water column is developed and compared to existing theory. Acoustic signals will be analyzed using a matched filter, fluctuations will be computed in normalized level and variance of time of arrival. Temperature variations will be computed as mean-square fluctuations of the index of refraction. Other physical mechanisms contributing to acoustic fluctuations including source/receiver motion, turbulence, and internal waves are also investigated.