Acoustic sensor coverage variation due to water stratification in estuaries

Abstract

Monitoring underwater environments is critical for future near-shore exploration and port security. The effectiveness of underwater acoustic sensor systems is affected by the water environment, as sharp gradients in salinity and temperature cause sound to refract and reflect. Sound transmission can be impaired in estuaries where the salinity of the water is highly variable in space, and tidal action causes water conditions to change as a function of time. We study the behavior of estuarine water conditions and characterize the acoustic sensing range in an estuary using environmental data extracted from the forecast model of the Hudson River. We analyzed the shape of sound speed profiles and performed statistical analysis of the distribution of highly stratified water. Sound propagation is computed using a beam tracing model. The variation of sensing range is evaluated and correlated to the level of water stratification.