• Title/Summary/Keyword: Cheju strait

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A Systematic Study on the Korean Anthozoa 12. ORder Scleractinia (한국산 산호충류의 계통분류학적 연구 12. 돌산호목)

  • 송준임
    • Animal Systematics, Evolution and Diversity
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    • v.7 no.1
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    • pp.127-150
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    • 1991
  • The stony corals known from Korean waters are 24 species , 15 genera, 7 families in 5 suborders, of which 7 species are newly recorded to the Korean scleractinian fauna ; Montipora trabeculata, Oulangia stokesiana miltoni, Goniocorella dumosa, Dendrophyllia arbuscula, D.boschmai cyathohelioides, D. micranthus, and Rhizopsammia minuta mutsuensis. They were collected from 35 localities of southern Korea from 1969 to 1986. For the geographical analysis, the coastal waters of Koarea are divided into four regions ; the Yellow Sea, the Korea Strait, the Cheju Island area and the East Sea (Sea of Japan) . These are based on the species diversity , the geographical distribution form, and the community coefficient, Korean scleractinians consists of 8 temperate zone forms(33.3%, Te) and 16 tropical forms(66.7%, Tr) . Concerning the distribution in each region, 3 spp. (2 Te, 1 Tr) occur in the Yellow Sea, 9 Spp. (5 Te, 4 Tr) in the Korea Strait, 16 spp.(4 Te, 12 Tr) in the Cheju Island area and 5 spp. (2 Te, 3 Tr) in the East Sea. The communicty coefficient between the Korea strait and the East Sea is the highest (0.596), and that between the Yellow Sea and the Cheju Island area is the lowest(0).

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A Numerical simulation for the circulation of sea water in the Southern Coastal Waters in Korea (한국 남해안에서 2차원 해수순환모델)

  • KWOUN Chul Hui;CHO Kyu Dae;KIM Dong Sun
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.5 no.4
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    • pp.27-40
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    • 2002
  • The circulation of sea water was simulated by two dimensional tide model using the main four tidal components and permanent current driven by inflow/outflow across open boundaries. According to the residt of tide model, the maximum speed of eastward flow on the Cheju Strait is twice higher than that of westward flow. According to the result of permanent current, the flow of permanent current showing semi-circle pattern in the southern part of Kojedo was due to variation of topography. According to the result of circulation model in the Cheju Strait, eastward flow entering in the southern waters from the Yellow Sea of Korea were dominant, but outflows westward were weak. These results suggest that it was difficult to move for suspended particulate matter into the Yellow sea from the southern waters through Cheju Strait.

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Environmental Characteristics and Catch Fluctuations of Set Net Ground in the Coastal Water of Hanlim in Cheju Island I. Properties of Temperature and Salinity (제주도 한림 연안 정치망어장의 환경특성과 어획량변동에 관한 연구 I. 수온 및 염분특성)

  • KIM Jun-Teck;JEONG Dong-Gun;RHO Hong-Kil
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.31 no.6
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    • pp.859-868
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    • 1998
  • In order to investigate the relation between the marine environmental characteristics and the change of the catch in set net, the marine environment properties were analyzed by temperature and salinity observed in the western coastal area of Cheju Island from 1995 to 1996 and the results are as follows 1) Main axis of Tsushima Current appeared in the western coastal area of Cheju Island was off 2$\~$3 miles from November to May. Therefore the waters of high temperature over $14^{\circ}C$ and high salinity from $34.40\%_{\circ}$ to $34.60\%_{\circ}$ were distributed homogeneously from surface to bottom in this time. But China Coastal Waters of low salinity appeared in the Cheju Strait from June to October, surface waters became of high temperature and low salinity, and middle and bottom waters became of the temperature from 11 to $14^{\circ}C$ and the salinity over $33.50\%_{\circ}$ and then vertically sharp thermocline and halocline are formed in the western coastal area of Cheju Island. In summer, the water temperature and salinity of the surface waters in wstern coastal area of Cheju Island were lower and higher respectively than that in middle area of the Cheju Strait and the temperature and salinity of the bottom waters in this area were higher and lower, respectively than that in middle area of the Cheju Strait. Such a distribution shows a tidal front in this coastal area. On the whole year, surface temperature and salinity were from 14 to $23^{\circ}C$ and from 30.60 to $34.60\%_{\circ}$, respectively, and annual fluctuation range of temperature and salinity was within $9^{\circ}C$ and $4.00\%_{\circ}$, respectively, Thus, annual fluctuation range in this area is much narrower than that in the Cheju Strait. In bottom water, temperature ranges from 14 to $20^{\circ}C$ through the year. Thus, the fluctuation range of temperature is narrow. The low temperature of from $11^{\circ}C$ to $13^{\circ}C$ appeared in the west enterance of Cheju Strait was not shown in this coastal area. 2) The salinity of bottom water was from $33.60\%_{\circ}$ to $34.40\%_{\circ}$ in 1995, while low salinity wale. below $32.00\%_{\circ}$ appeared all depth from June in 1996. Thus, the variation of hydrographic conditions in this area is narrow in winter, and wide in summer due to the influence of China Coastal Waters. 3) In summer, surface cold water, local eddy and fronts of temperature and salinity were showed within 2 mile from the west coast of the Cheju Island due to vertical mixing by tidal current. Especially, temperature and salinity of bottom water are changed with the change of depth around Biyang-Do. Thus, the front of temperature and salinity appeared clearly between shallow area with the depth of under 10 m and deep area with of the depth of more than 50m. Surface water in outside area where high temperature and low salinity water appear intrudes between Worlreong-Ri and Geumreung-Ri. Thus, the front of temperature and salinity was made along the line that connects from this coast to Biyang-Do, The temperature of the bottom water is $2^{\circ}C$ to $4^{\circ}C$ lower than that of the surface water and its salinity is $0.02\%_{\circ}$ to $0.08\%_{\circ}$ higher than that of the surface water even in shallow area.

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A Study of the Hydrographic Conditions and Tidal Front on the Northern Coastal Area of Cheju Island (제주도 북부연안역의 해황과 조석전선 특성)

  • Kim Sang-Hyun;RHO Hong-Kil;CHOI Chan-Moon
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.31 no.3
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    • pp.437-446
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    • 1998
  • The general pattern of the hydrographic conditions and tidal front of the northern coastal area of Cheju Island is investigated using the CTD observation data and a stratification parameter V ($J/m^3$) in $1991\~1993$. 1. The sea water of the northern coastal area of Cheju Island has a lower temperature and higher salinity than that in the central area of the Strait, and local temperature and salinity fronts appears frequently around this area. It seems that they are caused by the upwelling and the tidal front as well as a local topography. 2. A saddle-like distribution of temperature and salinity is formed in the Cheju Strait almost every month with relation to mixing of the different water masses. 3. In the northern coastal area of Cheju Island the stratification parameter V ($J/m^3$) was ranged from 8.4 to 209.8 $J/m^3$ in June, 201.9 to 634.9 $J/m^3$ in August, 0.18 to 680 $J/m^3$ in September, and $2.7\~462\;J/m^3$ in October, respectively. The tidal front was often formed around the place where the horizontal variation of the depth is very large and the potential energy with 10$J/m^3$ appears roughly along 50 m isobath.

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Characteristics of Front near the Cheju Strait in Early Winter (초겨울 제주해협 근해에서 형성되는 전선의 특성)

  • LEE Jae Chul
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.16 no.2
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    • pp.51-58
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    • 1983
  • Off the southwest coast of Korea, changes in hydrographic fields from stratified state of summer to a vertically homogeneous one of winter appeared to occur most actively in November. During this transitional period coincident thermal and salinity fronts are formed along the boundary between the two water masses of cold coastal water with low salinity and of the Tsushima Current Water. Generally frontal zone lies where the bottom depth is about 70-90m except for the central region of the Cheju Strait in which the influence of the Tsushima Current is weak. Result of the drift bottle experiment in November 1930 supports the existence of the westward coastal current.

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Wind-induced Spatial and Temporal Variations in the Thermohaline Front in the Jeju Strait, Korea

  • Han, In-Seong;Suh, Young-Sang;Seong, Ki-Tack
    • Fisheries and Aquatic Sciences
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    • v.16 no.2
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    • pp.117-124
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    • 2013
  • We investigated the short-term and local changes in the thermohaline front in the Jeju Strait, Korea, which is usually formed during winter and spring. To do so, we compared Real-Time Observation System by Ferryboat (RTOSF) data with wind data and routinely collected oceanographic data. During February and April 2007, a thermohaline front formed in the Jeju Strait around the 13-$14^{\circ}C$ isotherms and 33.0-33.5 isohalines. The thermohaline was clearly weakened and began moving southward in mid-March. The variations in the surface temperature and salinity showed a continuous north-south oscillation of the thermohaline front with a period of 3-10 days. The speed of the short-term and local fluctuation of thermohaline front was about 5-30 cm/s. We confirmed these findings by examining the variation in the maximum temperature gradient and $14^{\circ}C$ isotherm during the study period. These short-term and local changes had not been previously detected using serial oceanographic and satellite data. Analysis of local wind data revealed a northerly wind fluctuation with a period of 3-10 days, which was clearly related to the short-term and local changes in the thermohaline front. The short-term and local changes of the thermohaline front in the Jeju Strait originated from local changes in the winter monsoon in this area.

Fauna of Caprellidae (Amphipoda) of Cheju Island and its Adjacent waters, Korea (제주도 해역의 바다대벌레류( 갑각류, 서각목))

  • Lee, Kyung-Sook
    • Animal Systematics, Evolution and Diversity
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    • no.nspc2
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    • pp.97-106
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    • 1988
  • Fifteen caprellid species in 5 genera were identifice during the study period from February to July , 1987 at 16 localites in Cheju Island and adjacent waters. Of which 5 species in 5 genera are newly reported from Korea ; Caprella kominatoensis Takeuchi, 1986. Protomima imittrix Mayer, 1903. Pseudoproto fallax Mayer, 1903, Paraprotella prima Mayer, 1903 and Protella gracilis Dana, 1853.

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CALCAREOUS NANNOPLANKTON FROM THE SEOGUIPO FORMATIN OF CHEJU ISLAND, KOREA AND ITS PALEOCEANOGRAPHIC IMPLICATIONS

  • Yi Songsuk;Yun Hyesu;Choi Duck-Keun;Yoon Sun;Koh Gi-Won
    • 한국석유지질학회:학술대회논문집
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    • spring
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    • pp.22-28
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    • 1998
  • Twenty species of calcareous nannofossils belonging to 11 genera are identified from the Seoguipo Formation in Cheju island, Korea. On the basis of the marker species, the Seoguipo Formation is biostratigraphically assigned to the Pseudoemiliania lacunosa Zone (NNl9), which corresponds to the combined zones of Emiliania annula - Emiliania ovata (CN13a-CN14a) of latest Pliocene and Early Pleistocene. Generally, cold-water species is dominant in the lower part, whereas warm-water one in the upper part. This is interpreted the palaeoceanographic condition has changed from cooling to warm phase. The change in floral composition and abundance of specific species allows the recognition of 4 ecostaratigraphic units in the Seoguipo Formation and the migration of oceanographic frontal boundary. According to nannofossil distribution in the study area, the position of an oceanographic boundary between warmer water and cooler water appeared to have oscillated north-south over the Korea Strait and Cheju island in response to glacial and interglacial cycles. The geologic time of the interpreted paleoceanographical changes determined by nannofossil biochronology is well agreed with the results obtained from the Japan Sea (East Sea) and Japan-Sea side of Japan.

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In Summer, the Origin of Tsushima Warm Current Water in the Western Channel of the Korea Strait-2 on the Water in the Middle Layer (하계 대한해협 서수도에 유입되는 Tsushima난류수의 기원-2 중층수에 대한 고찰)

  • 윤종휘
    • Journal of the Korean Institute of Navigation
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    • v.14 no.2
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    • pp.61-76
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    • 1990
  • It was found that three different water masses were vertically situated in the western channel of the Korea Strait in summer. Of these water masses , the origin and inflow path of the middle water were discussed and estimated by comparing with water characteristics of neighbouring sea. As a result, (1) the middle water is formed on the continental shelf in the East China Sea by the mixing of the Kuroshio Water and Chinese Continental Coastal Water, (2) the middle water seems intruded through the sea around 127 E west off Kyushu Island and east off Cheju the Island.

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Fluctuation Characteristic of Temperature and Salinity in Coastal Waters around Jeju Island (제주도 연안 천해역의 수온 · 염분 변동 특성)

  • KO Jun-Cheol;KIM Jun-Teck;KIM Sang-Hyun;RHO Hong-Kil
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.36 no.3
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    • pp.306-316
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    • 2003
  • We conducted a time-series analysis of temperature and salinity of sea water around Jeju Island, Korea. Monthly mean temperature and salinity was influenced by precipitation and weather conditions on Jeju as well as by oceanographic conditions of the open sea such as the Tsushima Warm Current and sea water in coastal areas. Salinity of Jeju coastal waters was the highest in April, and it was always over 34.00 psu with tiny fluctuation between December and June. Due to the effects of the Tsushima Warm Current, Jeju coastal waters maintained high salinity and stability. Low salinity and its large fluctuations during summer were closely associated with the China Coastal Water and precipitation in Jeju. The place of the lowest water temperature was the northeast coasts of Jeju (Gimneong, Hado, Jongdalri). In winter, as warmer water of the Tsushima Warm Current appeared in western area of Jeju dwindled flowing along the northern coasts of Jeju area and becoming cool, the lowest water temperature often appeared locally in Gimnyeong and its vicinitly in summer. The Tsushima Warm Current flows into the east entrance of Jeju Strait, but its influence is weak because of geometry and strong vertical mixing due to fast tidal currents.