Effects of Korean littoral environment on acoustic propagation

Environmental acoustics experiments were recently conducted in shallow to i ntermediate water depths in the Sea of Japan, east of Korea, along the shel f and slope, covering frequencies from 25 to 800 Hz, These were operational experiments carried out in three different seasons. The primary objectives of the data reported here are: 1) to characterize the Korean coastal envir onment during May 1998, September 1998, and February 1999 and 2) to assess how complexities of the environment might impact acoustic propagation in Ma y and February, as measured by its transmission loss. Propagation data were obtained from broadband explosive SUS sources and sonobuoy receivers. The tests were conducted over varying bottom depths and slopes, both approximat ely normal and parallel to the bathymetric contours. Two different source d epths were included. Environmental and acoustic data are reviewed and discu ssed. While many aspects of the observed propagation remain ill understood, on the whole a consistent and useful picture has emerged of acoustic propa gation in this region. Environmental impacts on propagation are associated mainly with bottom properties, somewhat less so with source depth in relati onship to sound speed profiles, and almost not at all with range-dependent profiles of a water mass front.