Probability density measurements for cw propagation in the Arctic ocean

An experimental investigation of signal amplitude and phase fluctuations under Arctic conditions has been conducted. The data were sampled from low-frequency cw transmissions during the FRAM IV experiment in April 1982. The signals were generated at the Tristen ice camp and received at the FRAM IV ice camp located north of Spitzbergen. The average water depth along the propagation paths was 3000 m. The range was approximately 275 km. The 28 receivers were positioned along a vertical array at depths from 30 to 960 m. The single hydrophone data exhibited a high signal-to-noise ratio (⩾10 dB) and a high phase stability. The measured phase was modified by means of a frequency shift to compensate for relative platform motion. Histograms of the single hydrophone amplitude and phase were examined for goodness of fit to hypothetical density functions. Amplitude and phase distributions were consistent with a multipath fluctuation model, at the 0.05 level of significance. These densities are associated with a partially saturated process. They were first theoretically derived by P. N. Mikhalevsky [J. Acoust. Soc. Am. 72, 151–158 (1982)].