• Ocean Science Journal
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• v.41 no.3
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• pp.181-189
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• 2006

Frontal areas between warm and saline waters of the Kuroshio currents and colder and diluted waters of the East China Sea (ECS) influenced by the Changjiang River were identified from the satellite thermal imagery and hydrological data obtained from the Coastal Ocean Process Experiment (COPEX) cruise during the period between March $1^{st}$ and $10^{th}$, 1997. High chlorophyll concentrations appeared in the fronts of the East China Seas with the highest chlorophyll-a concentration in the southwestern area of Jeju Island (${\sim}2.9\;mg/m^3$) and the eastern area of the Changjiang River Mouth (${\sim}2.8\;mg/m^3$). Vertical structures of temperature, salinity and density were similar, showing the fronts between ECS and Kuroshio waters. The water column was well mixed in the shelf waters and was stratified around the fronts. It is inferred that the optimal condition for light utilization and nutrients induced both from the coastal and deep waters enhances the high phytoplankton productivity in the fronts of the ECS. In addition, the high chlorophyll-a in the fronts seems to have been associated with the water column stability as well.

• Journal of the Korean Society for Marine Environment & Energy
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• v.12 no.4
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• pp.235-247
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• 2009

In order to elucidate the cause of Cochlodinium polykrikoides blooms in the Korea southern coastal water, we investigated observational data of water temperatures and salinities in summer and winter, obtained from the stoppage of ship by NFRDI (National Fisheries Research and Development Institute) as well as composite images by NOAA from 1995 to 2008. Cochlodinium polykrikoides blooms occurred when water temperature was approximately $25.0{\sim}26.0^{\circ}C$ and salinity was 31.00 psu on average in Narodo neighboring seas. Different thermohaline fronts were observed between the Korea southern coastal water and the open sea water in summer and winter, respectively. That is, in winter four fronts were observed between the Korea southern coastal water with low temperature and low salinity, intermediate water originated from Tsushima Warm Current, Tsushima Warm Current with high temperature and high salinity, and the China coastal water with low temperature and low salinity. In contrast, in summer two fronts were observed between the Korea southern coastal water with low temperature and high salinity, Tsushima Warm Current with high temperature and low salinity, and the China coastal water with high temperature and high salinity. These thermohaline fronts also proved to be formed by two water masses with a different physical property, in terms of T-S diagrams. Consequently, we noticed that C. polykrikoides blooms occurring in Narodo neighboring seas in summer had a close relationship with thermohaline fronts observed between the Korea southern coastal water and Tsushima Warm Current.

• Journal of Fisheries and Marine Sciences Education
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• v.24 no.2
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• pp.333-345
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• 2012

NOAA/AVHRR, Topex/Poseidon, and Jason-1 data were used to analyze sea surface temperatures and thermal fronts in the North East Asia Seas. Temporal and spatial analyses were based on data from 1993 to 2008. The amplitude and phase for the annual mode on SL and SST were investigated with harmonic analysis. The geographical distribution of amplitudes for comparison of SL and SST are slightly reverse in southwest-northeast tilted direction. The time series analysis conducted on the entire researched area presented consistent pattern. Peak of Sea Level was presented 1~2 months after the peak of the surface sea temperature was shown. This explains that Sea Level change occurs after the generation of surface sea temperature change in sea. The Sobel edge detection method delineated four fronts. Thermal fronts generally occurred over steep bathymetric slopes. Annual amplitudes and phases were bounded within these frontal areas.

• 한국해양학회지
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• v.22 no.2
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• pp.63-70
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• 1987

Existing oceanographic data indicate that tidal mixing fronts generally prevail in the Eastern Yellow Sea along the Korean coast. In the Western part, these fronts seem to be much weaker. These fronts are believed to be generated mostly by spatially different tidal mixing. The geostrophic adjustment model applied to the observed density structure gives the mixed coastal water flowing northward and the offshore waters(both surface warm and bottom cold waters) flowing southward along the Korean coast. The transport of each water amounts to O(10$\^$4/)m$\^$3//sec.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.5
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• pp.618-623
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• 1999

A relationship between SST (Sea Surface Temperature) fronts and formation of fishing grounds was examined using the data on fishing conditions obtained from 41 Korean purse-seiners during the period of 1991 to 1996. Good fishing grounds observed in the southern sea of Korea and the nothern area of the East China Sea were yearly found around the frontal zone and around the marginal area of Tsushima Current which was the periphery of fronts, Also, there were several fishing grounds, which are not related to the fronts. They can be classified into the following four types : The first type was found in the warm water pocket located in the western area of Cheju Island in winter. The second type was made in a intensive bending of isobathytherm with a higher temperature in the main stream of Tsushima Current between Cheju Island and the Goto Islands in winter. The third type was formed by the topographical vortex motion near the Tsushima Island in winter and spring. The fourth type was found at the area of the reflow Sea Warm Current in southwest sea of Korea between the costal front zone and the Yellow Bottom Cold Waters in summer and autumn.

• Korean Journal of Remote Sensing
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• v.21 no.3
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• pp.213-219
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• 2005

In the Korean seas, Sea Surface Temperature (SST) and Thermal ronts (TF) were analyzed temporally and spatially during 8 years from 1993 to 2000 using NOAA/AVHRR MCSST. In the application of EOF analysis for SST, the variance of the 1st mode was 97.6%. Temporal components showed annual variations, and spatial components showed that where it is closer to continents, the SST variations are higher. Temporal components of the 2nd mode presented higher values of 1993, 94 and 95 than those of other years. Although these phenomena were not remarkable, they could be considered ELNI . NO effects to the Korean seas as the time was when ELNI . NO occurred. The Sobel Edge Detection Method (SEDM) delineated four fronts: the Subpolar Front (SPF) separating the northern and southern parts of the East Sea; the Kuroshio Front (KF) in the East China Sea, the South Sea Coastal Front (SSCF) in the South Sea, and the Tidal Front (TDF) in the West Sea. TF generally occurred over steep bathymetry slopes, and spatial components of the 1st mode in SST were bounded within these frontal areas. EOF analysis of SST gradient values revealed the temporal and spatial variations of the TF. The SPF and SSCF were most intense in March and October; the KF was most significant in March and May.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.5
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• pp.695-706
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• 1998

SST (Sea Surface. Temperature) fronts which were found in the South-West Sea of Korea and the northern area of the East China Sea were examined in order to clarify their positions, shapes, seasonal changes and the formation mechanism, For this study used SST data rearranged from the SST IR image during 1991 to 1996 and oceanographical data obtained by National Fisheries Research and Development Institute. Temperature front in the Cheju Strait was analyzed by the data obtained from a fisheries guidance ship of Cheju Provincial Government, The coastal frontal zone in the South-West Sea of Korea and the offshore frontal zone in the northern area of the East China Sea can be divided into several types (Type of Winter, Summer, Spring, Autumn and late Autumn), Short term variations of SST fronts have a tendency not to move to any Bleat extent for several days. The location of the frontal zone in the southwestern sea of Cheju Island changes on a much large scale than that of the one in the southern coast of Korea, The frontal Tone, formed every year in the southern sea of Korea approaches closer to the coastal area in winter, and moves closer to the south in spring and autumn. The frontal zone of the southwestern sea of Cheju Island moves in a westerly direction from the east, and reaches its most westerly point in the winter and its most easterly point in the summer related to the seasonal change of the Tsushima Current. Additionally, the frontal zone of the southwestern sea of Korea becomes extremely weak in March, April and November. SST fronts are formed every year around the line connecting Cheju Island to Yeoseo Island or to Chungsan Island in the Cheju Strait. A Ring-shaped tidal mixing front appears along the coastal area of Cheju Island throughout the year except during the months from November to January. Especially, in May and October fronts are formed between the coastal waters of Cheju Island and the Tsushima currents connecting the frontal zone of the coastal region in the southern sea of Korea with that of the southwestern sea of Cheju Island.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.696-700
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• 2004

In the Korean seas, Sea Surface Temperature (SST) and Thermal Fronts (TF) were analyzed temporally and spatially during 8 years from 1993 to 2000 using NOAA/AVHRR MCSST. As the result of harmonic analysis, distributions of the mean SST were $10~25^{\circ}C,$ and generally SST decreased as latitude increased. SST increased in the order as following; the South Sea $(20\~23^{\circ}C),$ the East Sea $(17\~19^{\circ}C)$, and the West $Sea(13\~16^{\circ}C).$ Annual amplitudes and phases were $4\~11^{\circ}C,\;210\~240^{\circ}$ and high values were shown as following; the West Sea $(A1,\;9\~11^{\circ}C),$ the Northern East Sea $(A5,\;8\~9^{\circ}C),$ the Southern East Sea $(A4,\;6\~8^{\circ}C),$ the South Sea $(A3,\;6\~7^{\circ}C),$ the East China Sea $(A2,\;4\~7^{\circ}C)$ and phases; $A3\;(238\~242^{\circ}),\;A4\;(235\~240^{\circ}),\;A5\;(225\~235^{\circ}),\;Al\;(220\~230^{\circ}),\;A2\;(210\~235^{\circ}),$ respectively, Both of them were related inversely except the area A2, therefore the rest areas were affected by seasonal variations. TF were detected by Soble Edge Detection Method using gradient of SST. Consequently, TF were divided into 4 fronts; the Subpolar Front (SPF) based on the Cold Water Mass (low SST and salinity Subartic Water), resulting from the North Korea Cold Current (NKCC) and the East Sea Proper Cold Water in the middle and low layer, and the Warm Water Mass (high SST and salinity Subtropical Water), resulting from the Tsushima Warm Current (TWC) in area A4 and 5, the Kuroshio Front (KF) based on the Kuroshio Current (KC) and shelf waters in the East China Sea (ESC) in A2, and the South Sea Coastal Front (SSCF) based on the South Sea Coastal Water (SSCW) and TWC in A3. Also, the Tidal Front was weakly appeared in AI. TF located in steep slope of submarine topography. Annual amplitudes and phases were bounded in the same place, and these results should be considered to influence of seasonal variations.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.32 no.4
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• pp.395-401
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• 1996

In this paper, the propagation characteristics due to the horizontal water temperature variations in the sea such as thermal fronts is analyzed by the ray theory. Two models for the temperature anomaly layer are chosen. One is a plane type and the other is a cylindrical type. In the plane type, the temperature increases linearly from a isothermal region to 5km with the gradient of about $2^{\circ}C.$/km, and decreases with the same gradient in next 5km. In the cylindrical type, water temperature increases only with the same gradient from a half cylindrical thermal boundary surface. The result showed that the gradient of acoustic rays decreases in the temperature increasing region and vice versa in temperature decreasing region. And, the transmission loss due to the temperature variation was less than O.2dB in the plane type model as well as in the cylindrical one.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.4
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• pp.424-430
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• 2014

Two major temperature fronts, the Subpolar (Gosung, Gang-won-do; $38^{\circ}-41^{\circ}N$) and Thermal (Jukbyun, Gyeong-sang-buk-do; $36^{\circ}-37^{\circ}N$) fronts, are found in the East Sea along the east coast of Korea. These are located roughly where the Tsushima Warm Current and North Korea Cold Current intersect. To clarify the effect of the Thermal Front, we investigated seasonal variation in fish species composition using set nets in two areas located north (Jangho, Gang-won-do) and south (Hupo, Gyeong-sang-buk-do) of Jukbyun, Gyeong-sang-buk-do, and compared the sea water temperature and salinity. We collected a total of 38 fish species in Hupo and 25 in Jangho. Trachurus japonicus was the most common species at both sites, but the subdominant species differed. At Hupo, the subdominant species were Konosirus punctatus and Diodon holocanthus, whereas Clupea pallasii and Scomber japonicus were subdominant at Jangho. Based on Froese and Pauly (2014), subtropical fishes accounted for 55% of fish in Hupo but only for 33% in Jangho. The difference in fish species composition was most obvious in May and August. According to the Korea Hydrographic and Oceanographic Administration, sea surface temperature and salinity were slightly higher at Hupo than at Jangho. Our findings suggest that the oceanographic boundary resulting from the Thermal Front near Jukbyun, Gyeong-sang-bukdo may have a major effect on the distribution of migratory fish species.