Single-path acoustic scintillation results from the Shallow Water 2006 Experiment
DJ Tang, Daniel Rouseff, Frank Henyey, and Jie Yang

         In “sound transmission through a fluctuating ocean,” Flattxe et al. described saturation of a single acoustic path as that path becoming a number of interfering uncorrelated micropaths due to refraction by internal waves. The probability density function of intensity becomes exponential with a scintillation index of 1.0. In deep water, however, full saturation is not achieved due to weak scattering and absorption. Mid-frequency (1-10 kHz) data from the Shallow Water 2006 Experiment were used to determine single-path intensity statistics. At a range of 1 km in water 80 m deep, an acoustic path is isolated that went through upper turning points separated by a single bottom reflection. The data were collected during a period when large nonlinear internal waves were absent. The scintilation index calculated from the data increases with frequency until reaching a maximum of 1.2 around 6 kHz.It then decreases to 1.0 suggesting that single-path saturation can be achieved at mid-frequencies in shallow water. The probability density functions of intensity at various frequencies show a trend toward exponential. Because shallow water internal waves are dominated by the first mode, uncorrelated micropahs are an unlikely mechanism for producing the observed saturation.

Back to the WHOI SW06 home