• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.688-691
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• 2006

The current system of the East China Sea, a marginal sea in the northwest Pacific, has a seasonal variation. The Changjiang Diluted Water, Chinese coastal water in the East China Sea, has different seasonal paths. It flows southward along the Chinese coast within a narrow band in winter and does northeastward the Korea/Tsushima Strait in summer, which has been a subject to many researchers. In particular, low salinity in the South Sea of Korea in 1996 and 1998 was in discord with the Changjiang River discharge and the Changjiang Diluted Water seems to play an important role in occurrence of red tide in the South Sea of Korea in 1997 and on the contrary, disappearance in the next year. These facts suggested that the Changjiang Diluted Water does not flow along the same path in every summer. According to the analyses for path of the Changjiang Diluted Water using ocean color images by SeaWiFS and salinity observations by shipboard CTD in August for recent years, the Changjiang Diluted Water in summer flowed within the range of direction from southeastward to north-northeastward anticlockwise. However, the Changjiang Diluted Water flowed northeastward toward Jeju Island of Korea for the most part. It is necessary to examine the influence of major factors on path variability of the CDW in summer such as surface wind, the Changjiang River discharge and background current.

• 한국해양공학회지
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• 제24권6호
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• pp.23-29
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• 2010

Korean shipbuilding companies have sometimes carried out sea trials to measure a vessel's speed performance around the western channel of the Straits of Korea, where the flow fields are very complicated because of the effect of various flows such as sea, tidal, geostrophic, and wind-driven currents. Because these flows seem to present significant interference to a ship, the numerical reproduction of the flow-fields in the vicinity of the target sites could provide a better understanding of the sea environments while performing sea trials. In this study, we used the MEC ocean model to simulate the tidal currents around Tsushima Island and compared the simulated tidal amplitudes and currents with the measurements of Teague et al. (2001). The tidal amplitudes of the present simulation results agreed well with the observations. Based on the numerical simulation, the optimal direction and proper sites for a speed trial are described.

• Journal of the korean society of oceanography
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• 제32권3호
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• pp.128-137
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• 1997

This study presents results from a detailed sedimentological investigation of surface sediments obtained from the Korea Strait region, the southern part of the East Sea (Sea of Japan). The distribution of different types of bottom sediments is controlled by the recent fine-grained sediment transport and deposition combined with the lowerings of sea level during the last glacial period, forming a diverse mixture of organic-rich fine-grained and shelly coarse-grained sediments. In comparison to high organic concentration of fine-grained sediments in the inner continental shelf and slope areas, the shell-rich coarse-grained sediments on the outer shelf are discernible being further modified. These coarse-grained sediments are confirmed as relict resulting from the sediment dynamics during the lower sea levels of the last glacial period. Clay mineral distribution of the fine-grained sediments gives information about the transport mechanism. Presence of present-day current system (the Tsushima Warm Current) is most probable source for the fine-grained particles into the open East Sea from the East China Sea, indicating that Holocene sediment dynamics may be used to explain the observed distribution of surface coarse-grained shell-rich sediments.

• Ocean Science Journal
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• 제42권3호
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• pp.179-192
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• 2007

Understanding in climate effects on marine ecosystem is essential to utilize, predict, and conserve marine living resources in the 21st century. In this review paper, we summarized the past history and current status of Korean fisheries as well as the changes in climate and oceanographic phenomena since the 1960s. Ocean ecosystems in Korean waters can be divided into three, based on the marine commercial fish catches; the demersal ecosystem in the Yellow Sea and the East China Sea, the pelagic ecosystem in the Tsushima Warm Current from the East China Sea to the East/Japan Sea, and the demersal ecosystem in the northern part of the East/Japan Sea. Through the interdisciplinary retrospective analysis using available fisheries, oceanographic, and meteorological information in three important fish communities, the trend patterns in major commercial catches and the relationship between climate/environmental variability and responses of fish populations were identified. Much evidence revealed that marine ecosystems, including the fish community in Korean waters, has been seriously affected by oceanographic changes, and each species has responded differently. In general, species diversity is lessening, and mean trophic level of each ecosystem has decreased during the last $3\sim4$ decades. Future changes in fisheries due to global warming are also considered for major fisheries and aquaculture in Korean waters.

• 수산해양기술연구
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• 제21권1호
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• pp.62-66
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• 1985

영일만 해역에서 표면수온의 주기적 변화와 표면수온과 기온의 관계에서 얻은 결과는 다음과 같다. 영일만 해역(포항과 장기갑)에서 1962년 1월부터 1981년 12월까지 평균표면 수온이 높은 달은 10월과 11월뿐이다. 영일만 해역의 표면수온 주기적 변화는 쓰시마난류의 변화와 밀접한 관계를 갖는 다고 사료된다. 영일만에 장기갑의 누년 평균표면수온은 15$^{\circ}C$이고, 포항항에서는 14.6$^{\circ}C$였다.

• Journal of the korean society of oceanography
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• 제35권4호
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• pp.170-178
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• 2000

Low salinity water was observed during May in the Cheju Strait. Its structure and source were studied by using both the hydrographic data collected not only in the Cheju Strait during 1987-1989 but also in the wider area around Cheju Island extending to the Bank of Changjiang river in 1994 and the current data taken in the Strait during 1987-1989. The water had lower values of temperature, salinity, and density compared with the surrounding water and it was found in the surface layer outside of Tsushima Current Water 10-50 km off Cheju coast. The density of low salinity water was more dependent on salinity than on temperature. The low salinity water flowed into the Strait from the west as a series of intermittent waters whose size was variable in width and in thickness. The low salinity water was originated from the Chanajiang River Diluted Water. In the Cheju Strait, the water showed changes within 3 days on time and 30-50 km on space, and its sudden appearance was marked especially in May. Such strong variability and sudden appearance may be attributed to the beginning stage in May when the fresh water of Changjiang River Diluted Water starts to arrive in the Cheju Strait.

• 대한원격탐사학회지
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• 제22권5호
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• pp.397-402
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• 2006

China Coastal Water (CCW) usually appears in the seas surrounding Jeju Island annually (June-October) and is very pronounced in August. The power spectrum density (PSD), sea level anomalies (SLAs), and sea surface temperatures (SSTs) were found to peak annually and semiannually. The peaks at intervals of 80-, 60-, and 43-days are considered to be influenced by CCW and the Kuroshio Current. Generally, low-salinity water appears to the west of Jeju Island from June through October and gradually propagates to the east, where CCW meets the Tsushima Current. Empirical orthogonal function (EOF) analysis of SLAs and SSTs indicated that the variance in SLAs and SSTs was 55.70 and 98.09% in the first mode, respectively. The PSD for the first mode of EOF analysis of SLAs was stronger in the western than in the eastern waters because of the influence of CCW. The PSD for the EOF analysis of SSTs was similar in all areas (the Yangtze Estuary and the waters to the west and east of Jeju Island), with a period of approximately 260 days.

• Fisheries and Aquatic Sciences
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• 제27권2호
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• pp.76-86
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• 2024

The bio-logging method could be a valuable approach to studying the underwater movement of marine fish. We investigated the horizontal and vertical movement patterns of two yellowtails Seriola quinqueradiata weighing 8.7 kg and 9.5 kg with a popup satellite archival tag from October 2020 to January 2021 in the East Sea of Korea. Our results showed that a yellowtail migrated northward in October and November, and then shifted southward in mid-December. The average swimming depth and temperature of the fish monitored over 82 days were 24.9 ± 9.3 m (average ± SD) and 16.5 ± 1.9℃, respectively, and the total traveled distance was 1,172.4 km. The fish swam significantly deeper during the daytime (33.70 ± 14.80 m) than at nighttime (20.65 ± 8.44 m) from November to December (p < 0.05). These results suggest that the horizontal migratory route of yellowtails in accordance with the East Korea Warm Current which is the main branch of Tsushima Warm Current in the fall and early winter seasons, and showed significant diel vertical movement patterns from November to December.

• 한국환경과학회지
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• 제20권9호
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• pp.1141-1149
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• 2011

The three-dimensional hydrodynamic model was simulated to understand coastal sea front of formation and seasonal variation in the Southern Sea of Korea. In this study, we used to concept of stratification factor, to realize seasonal distribution of stratification coefficient which of seasonal residual flow, considered with, tide, wind and density effect. Tidal current tends to flow westward during the flood and eastward during ebb. The current by the wind stress showed to be much stronger the coastal than the offshore area in the surface layer. And the current by the horizontal gradient of water density showed to be relatively weak in the coastal area, with little seasonal differences. On the other hand, the flow in the offshore area showed results similar to that of the Tsushima Warm Current. The stratification factor (SHv) was calculated by taking into account the total flow of tide, wind and density effect. In summer, the calculated SHv distribution ranged from 2.0 to 2.5, similar to that of the coastal sea front. The horizontal temperature gradient showed to be strong during the winter, when the vertical stratification is weak. On the other hand, the horizontal gradient became weak in summer, during which vertical stratification is strong. Therefore, it is presume that the strength of vertical stratification and the horizontal temperature gradient affect the position of the coastal sea front.

• 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.