The history detectives: Establishing the parameters of the 1960 Perth-Bermuda antipodal acoustic propagation experiment

• Published in: The Journal of the Acoustical Society of America Vol. 134; no. 5_Supplement; p. 3989
• Main Author: Dushaw, Brian D.
• Format: Journal Article
• Language: English
• Published: 01.11.2013
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.4830543

In 1960 three 300-lb explosive shots were detonated off Perth, Australia at 3 am, 22 March (local) by HMAS Diamantina to determine if those sound signals could propagate the antipodal distance to the Bermuda SOFAR station. These data offer a rare measure of the ocean temperature a half century ago, averaged across large stretches of the Southern, South Atlantic, and North Atlantic Oceans. The accuracy of these data are determined by the accuracy of the essential parameters of the experiment, e.g., the time and position of the shots. The narrative of HMAS Diamantina the night of 21 March 1960 was reconstructed from the ship's log, the captain's Report of Monthly Proceedings, and other information. The experiment was conducted with care to obtain a precise measurement, subject to the resources available to the ship at the time. The largest uncertainty is in the position of the shots, determined by triangulation from shore landmarks in the evening, celestial navigation at dawn, and dead reckoning in between. In addition, the depth was measured at the time of the shots. The 1960 position was measured to an equivalent travel-time accuracy of about 3 s, biased toward closing the range to Bermuda.