An Empirical Approach to Investigate Environmental Effects on Acoustic Signal Speed in Oceanic Layers

This paper investigates and demonstrates the effects of three significant environmental contributors: temperature, depth and salinity impact on the acoustic signal propagation across distinctive ocean layers: Mixed, Thermocline and Deep Layers. In the field of underwater wireless sensor networks (UWSN), exact and precise determination of coordinates for sensor localization is very crucial for data validation. Temperature dominates the upper layers; depth becomes prime factors for deeper domain with minimal thermal variations. Salinity while having a diminished effect, facilitates to finer alterations in propagation and deviation of acoustic signal speed. In our work we have analyzed these interdependences by using different empirical models (e.g. Mckenzie, Medwin) customized to each layer, accounting to their incomparable environmental parameters. In Mixed layers sound speed variation are mainly thermal driven, where depth is minimal important and salinity effect is negligible but as we go deeper the temperature starts to fall and depth (pressure) started getting importance and also salinity and temperature variation almost become corresponding. By evaluating ocean layer specified empirical formulas, we have calculated average speed of sound and measure the respective contribution of all parameters. Our work has provided a sub structure which will help to optimize UWSN nodes identification or localization. The results of this work underscored the essential to have an adaptive sound speed modeling for enhanced and precise acoustic signal communication systems.