AFAR measurements of acoustic mutual coherence functions of time and frequency

A joint acoustic–oceanographic experiment was performed near the Azores in 1975. Frequencies from 400–4670 Hz were transmitted over a 35‐km wholly refracted path. In addition, a separate data set was gathered over a 3‐km path in 1973. Measurements of the mutual coherence function of time and frequency, and measurements of the acoustic phase structure function are presented and compared with predictions of fluctuations due to internal waves.