Use of acoustic frequency shifts for monitoring oceanographic processes in shallow water.

Abstract

Waveguide invariant theory is used to calculate the frequency shifts of the acoustic intensity spectral levels caused by environmental variability in shallow water. In winter conditions, long-term acoustic monitoring of tide and slope water intrusions has been demonstrated using measured frequency shifts of the acoustic intensity spectral levels [Turgut et al., J. Acoust. Soc. Am. 121, 2534–2541 (2007)]. Acoustic frequency shifts caused by other oceanographic processes such as background internal waves and solitary internal waves are also investigated. Additional broadband acoustic data from several summer experiments indicate the feasibility of extracting background internal wave parameters as well as internal solitary wave parameters when they propagate almost perpendicular to the acoustic propagation path. [This work was supported by the ONR.]