Assessing the Possibilities of Identifying Bowhead Whales on the Arctic Shelf

Acoustical Physics - Real recordings of bowhead whale signals and numerical simulation were used to investigate the propagation of such signals in an Arctic-type shallow-water waveguide. The...     

Application of Vertical Receiving Arrays for Underwater Acoustic Communication in an Inhomogeneous Waveguide under an Ice Cover

Doklady Physics - The results of experimental studies of underwater acoustic communication at frequencies of 500–1000 Hz using vertical chains of hydrophones (linear arrays) are presented....     

Tomographic inversion of measured cross-correlation functions of ocean noise in shallow water using ray theory

Based on experimental data obtained in 2012 in the Florida Strait, we study the feasibility of employing ray tomography to retrieve sound speed and flow velocity profiles from measured noise cross-correlation functions. We describe the results of numerical experiments that characterize the inversion errors resulting from peculiarities of the ray structure in shallow water, difficulties in unambiguous identification of ray arrivals, and a decrease in accuracy of ray theory at low frequencies. We show that under conditions of low-mode sound propagation, the use of the classical ray tomography scheme can yield only a rough estimate of the sound speed profile, but it allows approximate reconstruction of the current velocity profile. Application of passive ray tomography to the experimental data yields the current velocity profile in the Straits of Florida, which agrees with independent measurements within the inversion error limit.     

An Arctic-Type Shallow-Water Acoustic Waveguide as an Information Transmission Channel for Underwater Communications

Acoustical Physics - Model experiments are used to obtain the transfer functions of an Arctic-type shallow-water acoustic waveguide in the spring–summer period, including in the presence of...