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The diel vertical migration of the sound-scattering layer in the Yellow Sea Bottom Cold Water of the southeastern Yellow Sea: focus on its relationship with a temperature structure

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Acta Oceanologica Sinica 2013年第9期32卷 44-49页

作者： LEE Hyungbeen CHO Sungho KIM Woongseo kang donhyug Maritime Security Research Center Korea Institute of Ocean Science&Technology Deep-sea and Seabed Resources Research Division Korea Institute of Ocean Science&Technology

Using the hydroacoustic method with a 200 kHz scientific echo sounding system, the diel vertical migration （DVM） of the sound-scatteringlayer （SSL） in the Yellow Sea Bottom Cold Water （YSBCW） of the southeastern Yellow Sea was studied in April （spring） and August （summer） of 2010 and 2011. For each survey, 13-27 hours of acoustic data were continuously collected at a stationary station. The acoustic volume scattering strength （Sv） data were analyzed with temperature profile data. In the spring of both 2010 and 2011, the SSL clearly showed the vertical migration throughout the entire water column, moving from the surface layer at night to near the bottom during the day. Conductivity, temperature, and depth data indicated that the entire water column was well mixed with low temperature of about 8℃. However, the SSL showed different patterns in the summers of 2010 and 2011. In the summer of 2010 （≈28℃ at the surface）, the SSL migrated to near the bottom during the day, but there were two SSLs above and below the thermocline at depth of 10-30 m at night. In the summer of 2011 （≈20℃ at the surface）, the SSL extended throughout the entire water column at night, possibly owing to an abrupt change in sea weather conditions caused by the passage of a Typhoon Muifa over the study area. It was cancluded that the DVM patterns in summer in the YSBCW area may be greatly influenced by a strengthened or weakened thermocline.

关键词： diel vertical migration sound-scattering layer temperature structure typhoon Yellow Sea Bot- tom Cold Water

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High-frequency acoustic backscattering characteristics for acoustic detection of the red tide species Akashiwo sanguinea and Alexandrium affine

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Journal of Oceanology and Limnology 2019年第4期37卷 1268-1276页

作者： KIM Hansoo kang donhyug JUNG Seung Won KIM Mira Maritime Security and Safety Research Center Korea Institute of Ocean Science & Technology (KIOST) Busan 49111 Korea Department of Ocean System Engineering Jeju National University Jeju 63243 Korea Library of Marine Samples Korea Institute of Ocean Science & Technology (KIOST) Geoje 53201 Korea

Harmful algal blooms (HABs), caused by the overgrowth of certain phytoplankton species, have negative effects on marine environments and coastal fisheries. In addition to cell-counting methods using phytoplankton nets, a hydroacoustic technique based on acoustic backscattering has been proposed for the detection of phytoplankton blooms. However, little is known of the acoustic properties of HAB species. In this study, as essential data to support this technique, we measured the acoustic properties of two HAB species, Akashiwo sanguinea and Alexandrium affine, which occur in the South Sea off the coast of Korea. Due to the small size of the target, we used ultrasound for the measurements. Experiments were conducted under laboratory and field conditions. In the laboratory experiment, the acoustic signal received from each species was directly proportional to the cell abundance. We derived a relationship between the cell abundance and acoustic signal received for each species. The measured signals were compared to predictions of a fluid sphere scattering model. When A. sanguinea blooms appeared at an abundance greater than 3 500 cells/mL, the acoustic signals varied with cell abundance, showing a good correlation. These results confirm that acoustic measurements can be used to detect HAB species.

关键词： acoustic backscattering Akashiwo sanguinea Alexandrium affine fluid-sphere scattering model harmful algal blooms (HABs) red tide

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Ex situ echo sounder target strengths of ice krill Euphausia crystallorophias

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Chinese Journal of Oceanology and Limnology 2015年第3期33卷 802-808页

作者： Hyoung Sul LA Hyungbeen LEE donhyug kang SangHoon LEE Hyoung Chul SHIN Division of Polar Ocean Environment Research Korea Polar Research Institute Korea Institute of Ocean Science and Technology Maritime Security Research Center Korea Institute of Ocean Science and Technology

Ice krill is the keystone species in the neritic ecosystem in the Southern Ocean, where it replaces the more oceanic Antarctic krill. It is essential to understand the variation of target strength （TS in dB re l m^2） with the different body size to accurately estimate ice krill stocks. However, there is comparatively little knowledge of the acoustic backscatter of ice krill. The TS of individual, formalin-preserved, tethered ice krill was measured in a freshwater test tank at 38, 120, and 200 kHz with a calibrated split-beam echo sounder system. Mean TS was obtained from 21 individual ice krill with a broad range of body lengths （L： 13-36 iron）. The length （L, mm） to wet weight （W; mg） relationship for ice krill was 11/=0.001 21g^103~L35s （R2=0.96）. The mean TS-to-length relationship were TS38kHz=-177.4＋57log10（L）, （R^2=0.86）; TS120kHz= -129.9＋31.561ogf0（L）, （R2=0.87）; and TS200kHz=-117.6＋24.661ogre（L）, （R2=0.84）. Empirical estimates of the relationship between the TS and body length of ice krill were established at 38, 120, and 200 kHz and compared with predictions obtained from both the linear regression model of Greene et al. （1991） and the Stochastic Distorted Wave Born Approximation （SDWBA） model. This result might be applied to improve acoustic detection and density estimation of ice krill in the Southern Ocean. Further comparative studies are needed with in situ target strength including various body lengths of ice krill.

关键词： ice krill Euphausia crystallorophias ex situ target strength split-beam echo sounder

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