Examination of Broadband Low-Frequency Emitters in a Study of Temperature Regimes in the Sea of Japan

Abstract— The article considers the use of technical tools and methods of low-frequency hydroacoustics for monitoring the variability of average temperatures of underwater sound channels in the Sea of Japan. The authors review the characteristics of the line of powerful interpiston hydroacoustic emitters developed by the Institute of Applied Physics of the Russian Academy of Sciences, which are promising for organizing long acoustic tracks. The results of measuring the electroacoustic characteristics of low-frequency hydroacoustic emitters under natural conditions at depths of up to 150 m are presented, and the use of these emitters for studying the temperature regimes of associated underwater sound channels of the shelf and deep sea on multiscale long tracks in the Sea of Japan is also considered. Based on processing of experimental data on an acoustic path with a length of about 1000 km, obtained in 2022, examples are presented of reconstructing the average water temperature values from data on the sound speed along the acoustic path; the sensitivity of the method is assessed, and the signal-to-noise ratio values achieved in the experiment are analyzed.