Measurements and modeling of mid-frequency propagation loss during the Korea Reverberation Experiment 2017 (KOREX-17)

Sound propagation in shallow water is significantly influenced by fluctuation of the water medium and scattering from rough ocean boundaries. To study the effect of the intensity fluctuations caused by the various environmental effects, mid-frequency propagation loss measurements along with the ocean environmental measurements were conducted on May 25–31, 2017, in shallow water off Geoje island, as part of the Korea Reverberation Experiment 2017 (KOREX-17). Continuous wave and linear frequency modulated signal with a center frequency of 3.5 kHz were transmitted by the Autonomous Reverberation Measurement System (ARMS). The Self Recording Hydrophone (SRH) was towed by the R/V Mirae at a speed of approximately 3 knots along two different tracks. Sound speed profiles were measured using the moored CTD chain near the source location, covering the water column between 3 and 50 m. CTD casts were also conducted at the beginning and end of each track. In this talk, the fluctuations of measured propagation losses were presented for both tracks. Finally, the effects of the sound speed variations on the propagation loss will be discussed in comparison with the model predictions obtained using the measured sound speed profiles.