Deep scattering layers in the northwestern pacific

The large-scale horizontal variability of deep scattering layers (DSL) in the Northwestern Pacific is analyzed. The analysis is based on long-term measurements of the column strength and the volume scattering coefficient for frequencies from 0.63 to 16 kHz. The depth and frequency dependences of the scattering coefficient are presented for different regions of the aforementioned ocean region. The most pronounced changes in the DSL structure are found to occur at the boundaries between large-scale water masses or seas with different hydrological characteristics. By contrast, within such water masses and seas, the depth-frequency structure of the DSL remains relatively stable.