Experimental Study on the Impact of Seasonal Sound Speed Variability on Signal Detection Range in Arabian Sea

Elizabeth Shani N X; Nimmi R Nair; RP Raju; Sajeev R

doi:10.14429/dsj.72.17756

Elizabeth Shani N X Department of Physical Oceanography, School of Marine Science, Cochin University of Science and Technology, Kochi, Kerala, India https://orcid.org/0000-0003-1500-4322
Nimmi R Nair DRDO - Naval Physical and Oceanographic Laboratory, Thrikkakara, Kochi, Kerala, India https://orcid.org/0000-0002-7999-062X
RP Raju DRDO - Naval Physical and Oceanographic Laboratory, Thrikkakara, Kochi, Kerala, India https://orcid.org/0000-0002-3502-8113
Sajeev R Department of Physical Oceanography, School of Marine Science, Cochin University of Science and Technology, Kochi, Kerala, India https://orcid.org/0000-0001-9375-6808

DOI: https://doi.org/10.14429/dsj.72.17756

Keywords: Ambient noise, Indian ocean, Seasonal variability, Signal detection range, Transmission loss modeling

Abstract

Temporal variability of Signal Detection Range (SDR) with respect to measured noise level and sound speed is examined. An N x 2D acoustic model which included bathymetric variations, was used to study detection ranges for an area in Arabian Sea. Azimuthal and seasonal SDR at octave bands within 500 Hz were determined at different receiver depths. Study shows that seasonal change in sound speed profile resulted in high SDR and noise level in winter at the location. Study also confirms the significant seasonal difference in detection range corresponds to the cut off frequency at 160 Hz. Detection range for a receiver at a depth 40 m is observed to be high across the azimuth and seasons of study.