Features of Sound Scattering Along Non-Uniform Traces in the Sea of Japan and in the Sea of Okhotsk
Abstract:This article presents the results of sound scattering research along nonuniform traces in the Sea of Japan in the Sea of Okhotsk. The purpose is to determine the hydrophisical characteristics of small-scale inhomogeneties of sea medium and their spatial structure in the sea upper layer. Measurements of the sound scattering coefficients in the upper layer of the sea had been performed by the high frequency narrow beam sonar, which was maintained on the nose of the vessel. The complicated spatial structure of the small-scale inhomogeneities of the upper layer of the sea is revealed and characteristic variations of thermocline related with frontal zone and internal waves of different scale are analyzed. Estimations of biomass distribution on a base of sound scattering were obtained along different traces in the Sea of Japan in the sea of Okhotsk. The obtained results open new possibilities for the application of acoustic methods based on sound backscattering for monitoring of variability of small-scale structure in areas of the World Ocean with strong inhomogeneities like the frontal zone, currents and intensive fishery.
Research of sound scattering characteristics is of interest in order to assess the structure of the sea medium. This possibility is especially important near the frontal zones and borders of currents, when any contact methods do allow for detailed spatial observation of medium structure near the borders. Application of remote methods for sound scattering research in the top layer of sea water in a shelf zone and the shallow seas is of importance. Numerous researches of sound scattering along traces in the Sea of Japan were regularly carried out on research vessels the RV Impulse and the RV Malachite in 1998–2008 in its shelf zone with an exit on shelf border in the Bay of Peter the Great. In August 2010, during the expedition on the tall training ship Nadezda the sound scattering research in the Sea of Okhotsk was carried out. Traces along which sound scattering was investigated, were characterized by the presence of frontal zones, borders of currents and complexity of relief. Thus, sound scattering characteristics of the sea medium have changed significantly on borders of these inhomogeneities and therefore allowed visualizing the structure of such inhomogeneities with a good spatial resolution.
Document Type: Research Article
Publication date: January 1, 2011