• Ocean and Polar Research
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• 제26권4호
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• pp.595-606
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• 2004

Hydrographic survey in the Korea Strait has long history that has begun in August 1917 at the Busan - Tsushima cross section, still continues to date. However, chemical properties of bottom cold water found exclusively in the western channel of the Korea Strait during summer did not receive much scientific attention. The aim of the study is to decipher the enigmatic origin of the Korea Strait Bottom Cold Water (KSBCW) in terms of chemical properties. The physicochemical properties of the KSBCW are extracted from the CREAHS II hydrographic data. OMP method was applied to analyze origin of the KSBCW quantitatively. The KSBCW is well defined by low temperature below $10^{\circ}C$. The cold waters exhibited the local presence near the coast at about 120m depth with a thickness of 20m to 30m. The cold water was characterized by relatively cold, saline and higher chemical concentrations than adjacent waters. The KSBCW seems to have different origin kom that of the coastal upwelled waters at the Ulgi-Gampo because it is saline, denser and contains considerably less dissolved oxygen than upwelled waters. The physicochemical properties are reported to have noticeable annual variations which suggest the complex origin of the KSBCW. OMP analysis show that the KSBCW is a mixture of three water types; TMW (24%), ESIW (36%) and ESPW (40%). Relationship between the KSBCW and the east Sea circulation is traced by mapping the water masses that have similar T, S and DO of KSBCW. The result showed that the KSBCW is most possibly an extension of southward flowing coastal intermediate waters. Front these results, we expect that the monitoring KSBCW will provide us valuable information about the East Sea circulation.

• 한국수산과학회지
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• 제49권3호
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• pp.393-403
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• 2016

A steady, strong southward flow was observed in the lower layer beneath the Tsushima Warm Current in the deepest trough of the Korea Strait. Known as the Korea Strait Bottom Cold Water (KSBCW), this bottom current had a mean velocity of 24 cm/s and temperatures below 8–10℃. The direction of the bottom current was highly stable due to the topographic effects of the elongated trough. To determine the path of the southward bottom current, ADCP (Acoustic Doppler Current Profiler) data from 14 stations between 1999 and 2005 were examined. Persistent southward flows with average speeds of 4–10 cm/s were observed at only three places to the north of the strait where the bottom depths were 100–124 m. The collected data suggest a possible course of the southward bottom current along the southeast Korean coast before entering the deep trough of the Strait.

• Ocean and Polar Research
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• 제32권3호
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• pp.321-329
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• 2010

Photosynthetic pigments, nutrients, and hydrographic variables were examined in order to elucidate the spatio-temporal variation of water column structure and its effect on phytoplankton community structure in the western channel of the Korea Strait in fall 2006 and spring 2007. High phytoplankton biomass in the spring was associated with high salinity, implying that nutrients were not supplied by coastal waters or the Yangtze-River Diluted water (YRDW) with low salinity. Expansion of the Korea Strait Bottom Cold Water (KSBCW) and a cold eddy observed during the spring season might enhance the nutrient supply from the subsurface layer to the euphotic zone. Chemotaxonomic examination showed that diatoms accounted for 60-70% of total biomass, followed by dinoflagellates. Nutrient supply by physical phenomena such as the expansion of the KSBCW and the occurrence of a cold eddy appears to be the controlling factors of phytoplankton community composition in the Korea Strait. Further study is needed to elucidate the mechanisms by which the KSBCW is expanded, and its role in phytoplankton dynamics.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 1995년도 정기학술강연회 발표논문 초록집
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• pp.9-12
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• 1995

The Korea Strait becomes deeper than 200 m from south to north in general except coastal area, whereas its southern part is shallower than 125 m except for a deep trough (Fig.1). The flow in the Korea Strait could be simplified as two layers (Isobe, 1995)； the Tsushima Warm Water in the upper layer and the Korea Strait Bottom Cold Water (KSBCW) in the lower layer (Fig.2). (omitted)

• 한국어류학회지
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• 제19권4호
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• pp.378-386
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• 2007

대한해협의 서수도에서 출현하는 앨퉁이 어란의 발생 단계별 구성비를 연구하기 위해 수온, 염분, 난 자치어를 조사하였다. 조사해역에서 $10^{\circ}C$ 이하의 대한해협 저층냉수는 대한해협의 서수도에 위치한 울산 연안의 사면과 부산 근해의 저층에서 발견되었다. 어란은 조사해역의 모든 정점에서 출현하였다. 이들 정점에서 발생 단계별 어란의 구성비는 발생 초기가 37.7~89.5%, 중기가 8.5~37.8%, 후기가 0.0~24.7%였다. 어란의 출현량이 많은 곳은 대한해협 저층냉수의 세력이 강한 곳이었다. 이 해역을 포함한 인접해역에서는 발생 초기 어란의 비율이 73.3~89.5%로 매우 높았다. 이 어란들은 동해서남부 대륙붕단 주변해역의 산란장에서 울릉분지 내 $10^{\circ}C$ 이하의 냉수에 의해 대한해협의 서수도로 수송되어 누적된 것들로 추정된다. 반면 대한해협 저층냉수가 없는 대마도 북동 해역에서는 어란의 발생 초기의 비율이 37.5%로 매우 낮은 대신 중기와 후기의 비율이 각각 37.8%와 24.7%로 매우 높았다. 이러한 현상은 대한해협 저층냉수에 분포한 어란들이 상층의 대마난류수에 의해 다시 북쪽으로 수송되는 동안 발생이 진행되어 발생 초기보다는 중기나 후기단계의 어란들이 이 해역으로 가입되기 때문일 것이다. 이때 어란들의 일부가 부화하여 전기자어가 조사해역의 중부와 북부해역에 나타나는 것으로 보인다.

• 한국수산과학회지
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• 제46권2호
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• pp.186-194
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• 2013

We compiled and analyzed long-term time-series data collected in Korea to evaluate changes in oceanographic conditions and marine ecosystems near Jeju Island ($33^{\circ}00^{\prime}-34^{\circ}00^{\prime}\;N$, $125^{\circ}30^{\prime}-127^{\circ}30^{\prime}\;E$) from 1981 to 2010. Environmental data included depth-specific time series of temperature and salinity that have been measured bimonthly since 1961 in water columns at 175 fixed stations along 22 oceanographic lines in Korean waters by the National Fisheries Research & Development Institute, and time series of estimated volume transport of the Tsushima Warm Current (TWC) and Korea Strait Bottom Cold Water (KSBCW) for the period from 1961 to 2008. We analyzed the species composition in terms of biomass of fish species caught by Korean fishing vessels in the waters near Jeju Island (1981-2010). Data were summarized and related to environmental changes using canonical correspondence analysis (CCA). The CCA detected major shifts in fish community structure between 1982 and 1983 and between 1990 and 1992; the dominant species were a filefish during 1981-1992 and chub mackerel from 1992 to 2007. CCA suggested that water temperature and salinity in the mixed layer and the volume transport of the TWC and the KSBCW were significantly related to the long-term changes in the fish community in the waters off Jeju Island. Fish community shifts seemed to be related to the well-established 1989 regime shift in the North Pacific. Further studies are required to elucidate the mechanisms driving climate change effects on the thermal windows and habitat ranges of commercial species to develop fisheries management plans based on reliable projections of long-term changes in the oceanographic conditions in waters off Jeju Island.