• Journal of Environmental Science International
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• v.11 no.7
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• pp.627-636
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• 2002

While typhoons were passing by the coastal and offshore waters around the Korean peninsula, the variations of the sea surface temperature (SST) were studied. To study on the variation, the data related to the 22 typhoons among 346 typhoons which occurred in the western Pacific during 1990∼1999, daily measured field SSTs at coastal and offshore, and imageries from advanced very high resolution radiometer on NOAA satellite during 1990∼1999 were used. The average variations of the SSTs were -0.9℃ at coastal waters and -2℃ at offshore around the Korean peninsula while the typhoons were passing by. In very near coastal waters from the land, the SST was not changed because the bottom depth of the coastal waters was shallower than the depth of thermalcline, while the typhoon was passing. The temporal and spatial variation of SSTs at coastal waters in summer were depended on the various types of the typhoons＇paths which were passing through the Korean peninsula. When a typhoon passed by the western parts including the Yellow Sea of the Korean peninsula upwelling cold water occurred along the eastern coastal waters of the peninsula. The reason was estimated with the typhoon that was as very strong wind which blew from south toward north direction along the eastern shore of the peninsula, led to the Ekman transport from near the eastern coastal area toward the offshore. While cold water was occurring in the eastern coast, a typhoon passed over the coastal area, the cold water disappeared. The reason was estimated that the cold water was mixed up with the surrounding warm water by the effect of the typhoon. While a cold water was occurring in the eastern coast, a typhoon passed by the offshore of the eastern coast, there were the increasing of the SST as well as the disappearing of the cold water. While a typhoon was passing by the offshore of the eastern coast, the cold water which resulted from the strong tidal current in the western coast of the peninsula was horizontally spread from the onshore to the offshore. We think that the typhoon played the role of the very strong wind which was blowing from north toward south. Therefore, the Ekman transport occurred from the onshore toward the offshore of the western coast in the Korean peninsula.

• The Korean Journal of Malacology
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• v.11 no.1
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• pp.1-20
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• 1995

1993년 7월부터 1994년 5월까지 제주도 차귀도 4개 지점 조간대의 대형저서무척추동물의 분포와 군집구조에 관한 연구결과는 다음과 같다. 1. 차귀도 조간대에 분포하는 대형무척추동물은 총 9문, 17강, 35목, 75과, 146종이었다.2. 계절별 출현종수는 춘계에 124종, 하계 113종, 추계 99종, 동계에 86종이었다.3. 조간대 상부구역의 제1우점종은 좁쌀무늬총알고둥(N. exigua), 제2우점은 거북선(P. mitalla). (N.japonica),울타리고둥(M. labio), 중부구역은 배무래기(N. schrenkii), 밤고둥(C. argyrostoma lischkei), 울타리고둥, 깜장각시고둥(M. perplexa), 검은따개비(T. squamosa japonica)가 지점에 따라 제1, 제2우점종을 이루었다. 하부구역은 밤고둥, 검은따개비, 줄군부 (L. coreanica), 거북손, 굵은줄격판담치(S. virgatus)가 지점에 따라 우점하였으며, 상부구역 우점종의 군집우점지수는 매우 높았다.4. 조간대 하부구역의 종다양성은 상부구역이나 중부구역에 비하여 컸고 계절별 출현종수에 유의성이 있었으나 상부구역이나 중부구역에는 없었다.5. 종다양도지수와 균등도에는 상. 중. 하 구역별유의성은 없었고 풍부도에서는 상부구역에서 유의하였다.6. 제주 미기록종으로 부채넓적이끼벌레(D. su-bovoidea), 딱지조개(P. japonica), 목주림고둥(T. guerinii), 전촉수갯지렁이(A. validus), 바다거미(L. hilgendorfi)가 채집되었다.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.56 no.1
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• pp.11-17
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• 2020

The occurrence of eggs of hairtail, Trichiurus japonicus was examined in the coastal waters of Jeju Island, Korea in spring from May to June in 2014, April to May in 2015, and April to in 2016. As a whole, hairtail eggs occurred abundantly in May, 2014. Especially, high densities over 300 ind./1,000 ㎥ of eggs abundances in May and June, 2014 occurred in the north-western area of Jeju Island where is upwelling phenomenon occurred throughout the year. In the relationship between T-S and the hairtail eggs abundances, high densities over 100 ind./1,000 ㎥ of eggs abundances occurred in temperature of 18.1-18.7℃ and salinity of 33.92-34.87‰ in May when hairtail eggs occurred abundantly.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.3
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• pp.286-295
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• 2016

With the results of observations in 2013 and 2014 including ocean buoys, in-situ investigations and wind data, we examined the spatio-temporal variation of cold water masses along the eastern coast of Korea. Usually, a cold water mass first appears along the northern part of the eastern coast from May to July, and then along the southern part of the eastern coast from late June to mid-August. Cold water masses appear 3~5 times a year and remain for 5~20 days in the southwestern part of the East Sea. A distinctive cold water mass appeared usually in mid-July in this area, the surface temperature of which was below $10^{\circ}C$ in some cases. During the appearance of a cold water mass in the southwestern part of the East Sea, the horizontal temperature gradient was large at the surface and a significant low water temperature below $8^{\circ}C$ appeared at the bottom level. This appearance of cold water masses clearly corresponded to southwesterly winds, which generated coastal upwelling.

• Journal of the Korean Geophysical Society
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• v.9 no.3
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• pp.159-169
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• 2006

A GDS (Geomagnetic Depth Sounding) method, one of extremely low-frequency EM methods, has been carried out to examine conductivity anomalies in and around the Korean Peninsula. In this study, new GDS data acquired at the five sites in south-eastern area of the peninsula were incorporated into the previous GDS data. In order to quantitatively interpret observed induction arrows, the 3-D MT modeling considering the surrounding seas of the Korean Peninsula has been performed to evaluate sea effect at each GDS site. The modeling results revealed that the observed real induction arrows were not explained by solely sea effects, consequently two conductive structures that are responsible for the discrepancies between observed and calculated induction arrows were proposed. The first one is the Imjingang Belt, which is thought as an extension of Quiling-Dabie-sulu continental collision belt. The effects of the Imjingang Belt clearly appear at the site YIN and ICHN. The second one is the HCL (Highly Conductive Layer), which is considered as a conductive anomaly by mantle upwelling produced in back-basin region. The effects of the HCL are seen at the site KZU, KMT101, and KMT 107 in the south-eastern region of the Korean Peninsula.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.1
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• pp.40-48
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• 2001

The vertical distributions of temperature, salinity, dissolved oxygen, nutrients, chlorophyll, and primary production were investigated within the top 200m water depth in the south Pacific Ocean in February,2000. The study area ($24^{\circ}-41^{\circ}S,\;81^{\circ}-168^{\circ}W$) can be hydrologically divided into two regions. Upwelling was actively occurring in the eastern region of the $110^{\circ}S$ line, meanwhile it was not active in the western region. Accordingly, chemical properties in the surface waters were different between the two regions; nitrate+nitrite and phosphate concentrations were much higher in the eastern region than in the western region due to the active upwelling, but silicate concentration was higher in the western region. Among the nutrients, the major element influencing primary production was also different between the two regions; silicon would be a major element influencing primary production in the eastern region, but nitrogen may act as a major element for primary production in the western region. Primary production showed similar values in the two regions in spite of the large differences of nutrient concentrations in the surface waters, but the total chlorophyll integrated within the 200 m water depth was almost twice as much as in the western region than that in the eastern legion.

• 한국해양학회지
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• v.8 no.1
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• pp.22-32
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• 1973

Based on the plankton samples collected in the Korea Strait in 1972, a study was conducted on the vertical distribution of chaetognaths in relation to water masses in th Strait. The settling volume of total plankton collected in the Strait ranged from 0.3 to 5 cc/10㎥ and showed a distinctive variation in the vertical distribution between day and night. The large amount of volume was found in the upper layer at night and deeper layer during the day time collections. A total of 19 species and one forma of chaetognaths were identified from the present samples. In general, the number of species and individuals of chaetognaths were abundant in the upper layer. But in August they were distributed almost evenly from the surface to the bottom layer. Particularly several species of warm water chaetognaths, i. e., Sagitta enflata and S. regularis appeared abundantly in the deeper layer in summer. This indicates a sinking phenomenon of warm water from the surface to the bottom layer. As for the vertical distribution of S.elegans, a cold water species, in the Korean Strait, it is restricted only to the bottom layer except in the region of upwelling where they appear in the middle layer. This species is usually distributed in the depth of below 150m in the southern part of Japan Sea(Park, 1970), and it is usually distributed as far south as the Strait between Busan and Tsushima. In addtion, cold water species of copepods such as Pseudocalanus minutus and Metridialucens appear in the western side of Thushima. As indicated by the vertical and horizontal distribution of S. elegans in the Strait, the cold water flows as an undercurrent along the bottom from the southern part of the Japan Sea to the Korea Strait between Busan and Thushima in summer and fall, with a trend of uprising along the coast of Korea. S. decipiens has been found only in the depth of below 50m except in the coastal area where they appear in the upper layer. Therefore the vertical distribution of this species can be used for tracing the occurrence of upwelling and the movement of water from the middle layer.

• The Journal of the Petrological Society of Korea
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• v.26 no.1
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• pp.13-43
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• 2017

In the Hapcheon area, hypersthene-bearing monzonite (mangerite) and syenite are recognized. The main minerals of syenite are alkali feldspar, plagioclase, amphibole, biotite, and quartz. Anhedral hornblende and biotite are interstitial between feldspar and quartz, indicating that the hydrous minerals were crystallized later on. Based on petrochemical studies of major elements, syenite is alkaline series, metaluminous, and I-type. The variation patterns in the trace and rare earth elements of mangerite and syenite show the features of subduction-related igneous rock such as depletion of HFSE, relative enrichment in LILE to LREE, and negative Nb-P-Ti anomalies. Based on the experimental data and petrographic characteristics of the syenite, Hapcheon syenitic magma is considered to be formed by partial melting in a dry system. SHRIMP U-Pb zircon data yield the Triassic age as $227.4{\pm}1.4Ma$ in mangerite, $215.3{\pm}1.2Ma$ in syenite, and $217.9{\pm}2.6Ma$ in coarse-grained syenite, respectively. The mangerite age is similar to those of post-collisional plutonic rocks in Hongseong (226~233 Ma), Yangpyeong (227~231 Ma), and Odaesan (231~234 Ma) areas in the Gyeonggi Massif. Syenites were intruded after about 10 Ma. The features seen in the mangereite and syenite rocks can be explained by models such as the continental collision and slab break-off and the lithosphere thinning and asthenosphere upwelling model.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.5
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• pp.474-485
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• 2014

Temporal and spatial variations of temperature and salinity around Ganjeol Point during January, April, August and November 2011 were studied using the data from CTD observations and temperature monitoring buoys deployed at 20 stations in the southeast coast of Korea. Temperature and salinity were nearly homogeneous through the whole depth by mixing of the seawater in spring and winter related to the sea surface cooling. Stratification induced by the river runoff and the bottom cold water was clear in summer. In autumn, sea water had vertical mixing initiated from surface layer and weak stratification at the middle and bottom layers. Low temperature and high salinity emerged throughout the year near Ganjeol Point, which inferred from turbulent mixing and upwelling by its topographical effect. Major periods of 1/4~1.4 day temperature fluctuations were recorded for the most part of the stations. According to the cross spectral density analysis, high coherence and small time lag for temperature fluctuation between layers were shown at Ganjeol Point. However, those features at the northen area of Hoeya river were opposed to Ganjeol Point. From analyses, thermohaline structure and its fluctuation around Ganjeol Point were characterized into those three parts, the south of Ganjeol Point, Ganjeol Point and the north of Ganjeol Point.

• Ocean and Polar Research
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• v.30 no.4
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• pp.379-399
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• 2008

Spatial-temporal variations in physiochemical water qualities (temperature, salinity, DO, SPM, POC and nutrients) of surface and bottom waters were investigated along the mid-western coastal area (Taean Peninsula to Gomso Bay) of Korea. Spatial distribution patterns of temperature and salinity were mostly controlled by the physical mixing process of freshwater from Geum River and/or Gyunggi Bay with nearby coastal water. A strong tidal front is formed off Taean Peninsula during spring and summer. Seasonal variations in nutrient concentrations, lower in spring and summer and higher in fall and winter, are primarily regulated by magnitude of phytoplankton occurrence rather than freshwater loadings into the bay. Based on seasonal and spatial variability of physicochemical parameters, water quality of the study area can be divided into four water masses; Gyunggi Bay-influenced Water Mass (GBWM), Geum River-influenced Water Mass (GRWM), Yellow Sea Bottom Cold Water Mass (YSBCWM) and Cheonsu Bay Water Mass (CBWM). Water quality of the GBWM (Taean Peninsula coastal area), which has relatively low salinity and high concentrations of nutrients, is strongly controlled by the Gyunggi Bay coastal water, which is under influence of the Han River freshwater. In this water mass, the mixed layer is always developed by strong tidal mixing. As a result, a tidal front is formed along the offshore boundary of the mixed layer. Such tidal fronts probably play an important role in the distribution of phytoplankton communities, SPM and nutrients. The GRWM, with low salinity and high nutrients, especially during the flood summer season, is closely related to physiochemical properties of the Geum River. During the flood season, nutrient-enriched Geum River water mass extends up to 60 km away from the river mouth, potentially causing serious environmental problems such as eutrophication and unusual and/or noxious algal blooms. Offshore (<$30{\sim}40m$ in water depth) of the study area, YSBCWM coupled with a strong thermocline can be identified in spring-summer periods, exhibiting abundant nutrients in association with low temperature and limited biological activity. During spring and summer, a tidal front is formed in a transition zone between the coastal water mass and bottom cold water mass in the Yellow Sea, resulting in intensified upwelling and thereby supplying abundant nutrients to the GBWM and GRWM. Such cold bottom water mass and tidal front formation seems to play an important role in controlling water quality and further regulating physical ecosystem processes along mid-western Korean coastal area.