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Paleo-Tsushima Water influx to the East Sea during the lowest sea level of the late Quaternary

  • Lee, Eun-Il
    • Journal of the Korean earth science society
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    • v.26 no.7
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    • pp.714-724
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    • 2005
  • The East Sea, a semi-enclosed marginal sea with shallow straits in the northwest Pacific, is marked by the nearly geographic isolation and the low sea surface salinity during the last glacial maximum (LGM). The East Sea might have the only connection to the open ocean through the Korea Strait with a sill depth of 130 m, allowing the paleo-Tsushima Water to enter the sea during the LGM. The low paleosalinity associated with abnormally light $\delta^{18}O$ values of planktonic foraminifera is interpreted to have resulted from river discharge and precipitation. Nevertheless, two LGM features in the East Sea are disputable. This study attempts to estimate volume transport of the paleo-Tsushima Water via the Korea Strait and further examines its effect on the low sea surface salinity (SSS) during the lowest sea level of the LGM. The East Sea was not completely isolated, but partially linked to the northern East China Sea through the Korea Strait during the LGM. The volume transport of the paleo-Tsushima Water during the LGM is calculated approximately$(0.5\~2.1)\times10^{12}m^3/yr$ on the basis of the selected seismic reflection profiles along with bathymetry and current data. The annual influx of the paleo-Tsushima Water is low, compared to the 100 m-thick surface water volume $(about\;79.75\times10^{12}m^3)$ in the East Sea. The paleo-Tsushima Water influx might have changed the surface water properties within a geologically short time, potentially decreasing sea surface salinity. However, the effect of volume transport on the low sea surface salinity essentially depends on freshwater amounts within the paleo-Tsushima Water and excessive evaporation during the glacial lowstands of sea level. Even though the paleo-Tsushima Water is assumed to have been entirely freshwater at that time period, it would annually reduce only about 1‰ of salinity in the surface water of the East Sea. Thus, the paleo-Tsushima Water influx itself might not be large enough to significantly reduce the paleosalinity of about 100 m-thick surface layer during the LGM. This further suggests contribution of additional river discharges from nearby fluvial systems (e.g. the Amur River) to freshen the surface water.

Water Masses and Salinity in the Eastern Yellow Sea from Winter to Spring

  • Park, Moon-Jin;Oh, Hee-Jin
    • Ocean and Polar Research
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    • v.26 no.1
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    • pp.65-75
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    • 2004
  • In order to understand the water masses and their distribution in the eastern Yellow Sea from winter to spring, a cluster analysis was applied to the temperature and salinity data of Korea Oceanographic Data Center from 1970 to 1990. From December to April, Yellow Sea Cold Water (YSCW) dominates the eastern Yellow Sea, whereas Eastern Yellow Sea Mixed Water (MW) and Yellow Sea Warm Water (YSWW) are found in the southern part of the eastern Yellow Sea. MW appears at the frontal region around $34^{\circ}N$ between YSCW in the north and YSWW in the south. On the other hand, Tshushima Warm Water (TWW) is found around Jeju Island and the South Sea of Korea. These water masses are relatively well-mixed throughout the water column due to the winter monsoon. However, the water column begins to be stratified in spring due to increased solar heating, the diminishing winds and fresh water discharge, and the water masses in June may be separated into surface, intermediate and bottom layers of the water column. YSWW advances northwestward from December to February and retreats southeastward from February to April. This suggests a periodic movement of water masses in the southern part of the eastern Yellow Sea from winter to spring. YSWW may continue to move eastward with the prevailing eastward current to the South Sea from April to June. Also, the front relaxes in June, but the mixed water advances to the north, increasing salinity. The salinity is also higher in the nearshore region than offshore. This indicates an influx of oceanic water to the north in the nearshore region of the eastern Yellow Sea in spring in the form of mixed water.

Formation and Distribution of Low Salinity Water in East Sea Observed from the Aquarius Satellite (Aquarius 염분 관측 위성에 의한 동해 저염수의 형성과 유동 연구)

  • Lee, Dong-Kyu
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.51 no.2
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    • pp.187-198
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    • 2018
  • The monthly salinity maps from Aquarius satellite covering the entire East Sea were produced to analyze the low-salinity water appearing in fall every year. The low-salinity water in the northern East Sea began to appear in May-June, spreading southward along the coast and eastward north of the subpolar front. Low-salinity water from the East China Sea entered the East Sea through the Korea Strait from July to September and was mixed with low-salinity water from the northern East Sea in the Ulleung Basin. The strength of the low-salinity water from the East China Sea was dependent on the strength of the southerly wind of the East China Sea in July-August. The salinity reaches a minimum in September with a distribution parallel to the latitude of $37.5^{\circ}N$. In October, low salinity water is distributed along the mean current path and subpolar front and the entire East Sea is covered with the low salinity water in November. Water with salinity larger than 34 psu starts to flow into the East Sea through the Korea Strait in December and it expands gradually northward up to the subpolar front in January- February.

Water Mass Stability of Deep Ocean Water in the East Sea (동해 심층수의 수괴 안정성)

  • Moon D.S.;Jung D.H.;Shin P.K.;Kim H.J.
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • pp.285-289
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    • 2004
  • Oceanographic observation and qualitative analysis for deep ocean water in the East Sea were carried out from January 2003 to January 2004, in order to understand the characteristics of deep sea water in the East Sea. Temporal and spatial variation of water masses were discussed from survey of the study area including the coastal sea of Kwangwon province in where the polar front mixing cold and warm water masses were formed. On the basis of the vertical profiles of temperature, salinity and dissolved oxygen, water masses in the study area were divided into 5 major groups; (1) Low Saline Surface Water (LSSW) (2) Tsushima Surface water (TSW) (3) Tsushima Middle Water (TMW) (4) North Korea Cold Water (NKCW) and (5) East Sea Proper Water (ESPW). In winter, surface water in coastal sea of Kwangwaan Kosung region were dominated by North Korean Cold Water (NKCW). As Tsushima warm current were enforced in summer, various water masses were vertically emerged in study area, in order of TSW, TMW, NKCW and ESPW. It is highly possible that the LSSW which occurred at surface water of september is originated from influx of fresh water due to the seasonal rainy spell. Nevertheless water masses existed within surface water were seasonally varied, water quality characteristics of East Sea Proper Water (ESPW) under 300 m did not changed all the seasons of the year.

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Relationship between the Distribution of Water Masses and that of Demersal Fishes in the East China Sea in Spring

  • Cho Kyu Dae;Kim Hee Yong
    • Fisheries and aquatic sciences
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    • v.3 no.1
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    • pp.14-22
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    • 2000
  • The relationship between the distribution of demersal fishes and that of the water masses was examined by using the catches data and hydrographic data in the Yellow Sea and the East China Sea on May 13-19, 1996 and May 10-17, 1997. During the study period, the dominant fish species were Cleisthenes pinetorum herzinsteini, Lophiomus setigerus and Pseudosciaena polyactis. These three low temperature water species accounted for $21-24\%$ of the total catches. The percentage of the low temperature water species was high in the Yellow Sea and the coastal area on the continental shelf of the East China Sea but was low in the vincinity of Kyushu during the study period. In the East China Sea, the isotherm of $15^{\circ}C$ at 50m, mid layer depth, was located more southeast in 1996 than in 1997. The bottom water temperature was about it lower in 1996 than in 1997. The direction of the detided current on the continental shelf of the East China Sea was southward in 1996 and northward in 1997. Yellow Sea Bottom Cold Water (YSBCW) strongly expanded to south in 1996 when the northward current was weak. But, Tsushima Warm Current (TSWC) strongly intruded into the continental shelf of the East China Sea in 1997. As YSBCW expanded strongly to south in 1996, the percentage of the low temperature water species relative to the total catches was high. But, TSWC strongly intruded and the percentage of low temperature water fishes was low in 1997.

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A Seasonal Circulation in the East China Sea and the Yellow Sea and its Possible Cause

  • Oh, Kyung-Hee;Pang, Ig-Chan
    • Journal of the korean society of oceanography
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    • v.35 no.4
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    • pp.161-169
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    • 2000
  • A seasonal circulation in the East China Sea and the Yellow Sea and its possible cause have been studied with CSK data during 1965-1989. Water mass distributions are clear in winter, but not in summer because the upper layer waters are quite influenced by atmosphere. To solve the problem, a water mass analysis by mixing ratio is used for the lower layer waters. The results show that the distribution of Tsushima Warm Current Water expands to the Yellow Sea in winter and retreats to the East China Sea in summer. It means that there is a very slow seasonal circulation between the East China Sea and the Yellow Sea: Tsushima Warm Current Water flows into the Yellow Sea in winter and coastal water flows out of the Yellow Sea in summer. By the circulation, the front between Tsushima Warm Current Water and coastal water moves toward the shelf break in summer so that the flow is faster in the deeper region. The process eventually makes the transport in the Korea Strait increase. The Kuroshio does not seem to influence the process. A possible mechanism of the process is the seasonal change of sea surface slope due to different local effects of surface heating and diluting between the East China Sea and the Yellow Sea.

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Shallow Water Tides in the Seas around Korea

  • Kantha, Lakshmi H.;Bang, In-Kweon;Choi, Jei-Kook;Suk, Moon-Sik
    • Journal of the korean society of oceanography
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    • v.31 no.3
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    • pp.123-133
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    • 1996
  • We describe here the shallow water tides in the seas around Korea, obtained from a nonlinear barotropic model of tides in a domain encompassing the Yellow Sea, the East China Sea and the East Sea (Sea of Japan). As expected, the shallow water tides are large in the shallow marginal areas around the Yellow Sea, with the M4 tide reaching amplitudes as high as 10 cm near the Korean coast, and quite small in the East Sea. However, we also find that the regions east of the Yangtze River ($126^{\circ}E,$ $30^{\circ}N$) in the East China Sea also sustain large shallow water tides, with $M_{4}$, amplitudes reaching 5 cm. Such large shallow water tides are an important component of altimeter-measured sea levels and should not be ignored in any altimetric analyses of the Yellow Sea and the East China Sea. This study also highlights the desirability of very high resolution models to derive accurate shallow water tides in coastal regions.

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Sea Water Resistance of the Concrte Deteriorated by Repeat of Immersing and Drying in Sea Water (해수의 건습반복 촉진열화에 따른 콘크리트의 내해수성)

  • 박춘근;김병권;최재웅;고만기
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.307-312
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    • 1997
  • The sea water resistance of cement and concrete must be compared when it used for construction in the ocean. The sea water resistance of the concrete specimens using three types of cements such as ordinary Portland cement, sulfate resistance Portland cement, blastfurnace slag cement were studied. In this study, an accelerated test for access sea water resistance by subjecting the concrete specimens to repeated cycles of concentrated sea water immersion and hot wind drying was employed. This study proved that sulfate resistance Portland cement had higher resistance for sea water.

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Rheological Study on bentonite Clay Sedimentation with various concentrations of Sea water (해수의 농도 변화에 따른 bentonite 침전에 대한 유변학적 고찰)

  • 최상원;서호준
    • Journal of Environmental Science International
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    • v.5 no.1
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    • pp.35-41
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    • 1996
  • For studying of coagulation and sedimentation in estuarine clay, we obtained several flow curves with various concentrations of sea water by using Coutte type rotational rheometer. The initial shear stress on high concentration of sea water was observed big, but after this, its value is decreasing with increasing shear rate. The maximum pick of shear stress is decreasing with the decreasing of concentration of sea water The trend is same totally above for viscosity. The sedimentation times with the concentration of sea water vary in $\infty$ ~ 5 minutes. The zeta potential is changed dramatically between 114 and 118 concentration of sea water. That is consistent with the sedimentation graph. From these results, the phenomena of coagulation and sedimentation can be explained with viscoelastic terms on structual formation among particles by the changes of surface potential affected from contacting sea water to dispersed particles.

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Current Status of Domestic and Overseas Research of the Characteristics and Use of Deep Sea Water (해양심층수의 특성과 이용 및 국내외 연구현황)

  • Chung, Kap-Taeck;Lee, Sang-Hyun
    • The Korean Journal of Food And Nutrition
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    • v.21 no.4
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    • pp.592-598
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    • 2008
  • Deep sea water is found more than 200 m under the surface. As no sunlight reaches, no photosynthesis takes place, and it has very little organic matter or bacteria. In addition, deep sea water maintains a consistently low temperature throughout the year, and it does not mix with the water found closer to the surface, which means that its cleanliness is preserved. It is a long-term mature sea water resource that is rich in minerals. This paper examined the physical characteristics and the uses of deep sea water, a subject that has been attracting a great deal of public attention recently, together with the current status of domestic research into it and the direction of research in the USA and Japan, focusing on the existing literature. The aim of this paper was to provide are source to researchers in the field. Since the 1970s, scientists around the world have recognized the importance of deep sea water, and have been conducting research into it. In the USA, deep sea water has been researched with the view of its application to cooling, alternative energy, farming, and the development of new materials. In Japan, about 10 local self-governing bodies are currently promoting research and business relating to deep sea water, which has resulted in a number of products that have been released to the market. In Korea, the ministry of land transport and marine affairs has been studying deep sea water since 2000, and full-scale national R&D projects have been performed by 24 organizations, including KORDI, through industrial/academic cooperation. Large companies are participating in deep sea water research projects in several ways. A study of data foundusing NDSL relating to domestic studies of deep sea water found 50 theses, 177 domestic patents, 6 analyses, 2 reports, and 2 etc. in other areas.