Numerical simulation and measurements of acoustic transmissions from Heard Island to the equatorial Indian Ocean

Abstract

Simulated acoustic propagation showed a gradual deepening of the ray paths from the southern ocean towards tropics. Also the axis of the sound channel deepens from 150 m to 1600 m. Sudden jumps were noticed in the acoustic ray paths in the vicinity of the Sub Tropical Convergence. Measured acoustic signals, received at the Indian listening station has a signal to noise ratio (SNR) of 20 dB on an average and confirmed their detectability over distances as far as 7000 km. The phase stability of these signals allowed coherent averaging time of 20 minutes for corresponding increase in the SNR. Measured intensity losses were about 135 dB in contrast to those computed values of 150 dB.