Temporal Coherence of Acoustic Signal Transmissions in a Fluctuating Deep Ocean

Abstract

Temporal coherence of a propagating signal in the fluctuating ocean is an important property for many practical applications. In previous studies, it has been shown that the coherence time follows a [Formula: see text] power frequency dependence and a [Formula: see text] power range dependence for long-range deep-water propagations as well as for shallow water propagations. In this paper, the frequency and range dependences are studied for a relative near distance in the deep ocean based on the Monte Carlo simulations. The range is tens of kilometers and it cannot be regard as a long-range propagation. It is found in this paper that the [Formula: see text] power frequency dependence is still followed, while the simple [Formula: see text] power relationship is inadequate to show the range dependence in the near field of deep water. The signals mainly propagate through two different paths for tens of kilometers: the refracted path and the reflected paths. In different regions, the acoustic coherence times exhibit different dependences because the signals are dominated by different types of rays. The [Formula: see text] power range dependence still holds for the same kind of ray path.