Broadband acoustic variability due to internal solitary waves

A shallow water (70–90‐meter‐deep) broadband acoustic experiment with a source‐receiver range of 15–18 km in an azimuthally dependent environment was designed as a part of the SWARM’95 field study. Temporal behavior of the water column was sampled every minute from two sources placed above and below the thermocline transmitting signals over a period of several hours while the water column was measured for the passage of internal waves. Spatial behavior was sampled in the vertical plane by hydrophones with spacing on the order of meters. Coherence of broadband acoustic waves for frequencies (20–300 Hz) is examined for the waveguide over different environmental conditions. The effect of environmental variability on coherence, in particular the sound‐speed fluctuations in the water column due to the internal solitary waves, is noted as a function of acoustic frequency and azimuth. Analysis of the acoustic fluctuations over short time scales (10–15 minutes) may resolve the temporal decorrelation of the receiv...