CORRELATION BETWEEN INTERNAL SOLITONS AND AMPLITUDE VARIATIONS OF A SOUND SIGNAL ON A FIXED PATH

Experimental data are presented on simultaneous observation of acousti c signals, which propagated over a 34-km quasi-fixed path on the Pacif ic shelf, and a train of internal solitons that were measured by a dis tributed sensor near a hydrophone. Linearly frequency-modulated (in th e 725- to 885-Hz band) 6-s sound pulses with a repetition period of 30 s were used as probing signals. The received signals passed the filte r matched to the emitted pulse. The pulse frequency band was chosen so that the filtered signals arriving over the most ''rapid'' modes were not resolved and produced interference maxima whose amplitude was sen sitive to the phase difference of signals arriving over different mode s. A high correlation was observed between the fluctuations of the max ima of the signals delayed by 16.5 and 45 min and the soliton train fi ltered within the 0.7- to 2.4-mHz band. A numerical simulation was per formed to determine the acoustic path segments that were most sensitiv e to the effect of internal solitons and to estimate the direction of propagation for the soliton group.