Observations of acoustical scintillations in Saanich Inlet

An acoustical scintillation experiment was carried out in Saanich Inlet, British Columbia, using pseudo random coding on a 67 kHz carrier and two dimensional transmitting and receiving arrays. Acoustical multipaths are separated such that amplitude and phase fluctuations for a particular wholly refracted path are analysed. A maximum likelihood estimation technique is used to fit a sum of three paths to the received signal such that the error between the received signal and the modelled signal is minimized. The intensity fluctuations are approximately exponentially distributed and hence the multiple scatter propagation theory is applicable. Spectral analysis on time series of amplitude and phase will help determine a model for the random media. Refractive index fluctuations due to internal waves and finestructure may explain the large acoustic intensity variations observed in the data (scintillation index of 1.34)