Another look at the 1960 Perth to Bermuda long-range acoustic propagation experiment

Abstract

During a 1960 experiment on long-range ocean acoustic propagation, the signals of explosive shots made near Perth, Australia were recorded by a hydrophone array at Bermuda. The acoustic paths followed by those pulses are recalculated using a modern atlas for global ocean sound speed. The blocking or refractive effects of topographic features, besides continents, are ignored in this simple calculation. No direct path to the hydrophone array is obtained, and the array is found to be in the acoustic shadow by 300-400 km. The large energy of the 300-lb explosive sound sources required for adequate SNR at the receiver also points to a shadowed reception. Given nominal estimates for temperature warming on the sound channel axis due to climate change, the experiment repeated today would give signals that arrive 12 s earlier, but this signal could not be reliably measured because of intra-annual variability. Copyright 2008 by the American Geophysical Union.