• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.4
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• pp.353-360
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• 2010

The result of analysis of the observed temperature data by the Serial Oceanography Investigation of National Fisheries Research and Development Institute (NFRDI) during last 41 years from 1969 to 2008 showed that sea surface temperatures in the East, West and South Sea of Korea were clearly increased. In case of 100m depth, temperature was increased in the South Sea of Korea, but it was decreased in the East Sea. Especially, the temperature around the coastal area in the East Sea was significantly decreased by the spatial distribution of long-term change of temperature on 100m depth. It should lead to the decreasing trend in the long-term change of temperature on 100 m depth in the entire East Sea. The increasing trend was clearly larger in wintertime than in summertime by a factor of about 2 It means that the long-term increasing trend of sea surface temperature in the Korean Waters is usually caused by the distinctive increasing trend in wintertime. As the results of the analysis of air temperature and wind speed on the 6stations around the coastal area in the Korean Waters, air temperature was found to be continuously increased, but wind speed to be gradually decreased in winter. The weakness of vertical mixing by decreasing of wind speed caused to make the surface mixed layer shallow. it could be considered that the increasing trend of surface temperature was caused by weak mixing between surface and intermediate layers.

• Korean Journal of Environmental Biology
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• v.18 no.1
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• pp.77-93
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• 2000

Field survey on the spatio-temporal distribution of water quality and chlorophyll a concentration, and the environmental factors on the variation of phytoplankton biomass were carried out at the 23 stations for four seasons in the Shiahae, southwestern coast of Korean Peninsula from February to October in 1995. I made an analysis on biological factor as chlorophyll a concentration as well as environmental factors such as water temperature, salinity and nutrients; ammonia, nitrite, nitrate, dissolved inorganic nitrogen, phosphate, N/P ratio, silicate and Si/P ratio. The waters in the Shiahae were not stratified due to the tidal mixing and high velocity of tidal current. And the high productivity in photic layer were supported by high nutrients concentration from freshwater on lands and bottom waters The low depth of transparency in the Shiahae had a bad influence upon primary production and marine biology. In Shiahae had a sufficient nutrients for primary production during a year. Especially dissolved inorganic nitrogen and silicate were high, the other side, phosphate was low. The source of nutrients in summer and silicate supply depend on input of freshwater from lands, the other side, dissolved inorganic nitrogen and phosphate were depend on rather supplied from bottom layer by the mixing and input of seawater from outside than input of freshwater from lands. Phosphate seemed to become a limiting nutrient for the primary production at all area of Shiahae in winter and at the northern parts in other seasons. However, dissolved inorganic nitrogen seemed to do it at the southern parts in other seasons except winter. Silicate didn't become a limiting nutrient for diatoms in Shiahae. Phytoplankton biomass as measured by chlorophyll a concentration was very high all the year round, it was controlled by the combination of the several environmental factors, especially of nitrogen, phosphorus and the physical factors such as light intensity. [Spatio-temporal distribution, Seasonal fluctuation, Nnutrients, Chlorophyll a, Environmental factors, Nutrient source, Limiting Nutrient, Light, Shiahae] .

• Korean Journal of Fisheries and Aquatic Sciences
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• v.5 no.1
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• pp.1-10
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• 1972

Studies on the circulation and water masses in the continental shelf break region of the East China Sea are Summerized as follows : 1. The main stream of the Kuroshio flowing north-east near $29^{\circ}N\;Lat\;127^{\circ}E$ tong of the East China Sea in summer is narrow in width. Moving toward east, it becomes twice as wide in Tokora Strait, Japan. 2. In the main stream area of the Kuroshio, the surface Waters in the Upper layer (0-250m) are influenced by the coastal waters of China, and the counter current submerges under the surface water. Therefore, the mixing waters are found in its intermediate layer. 3. Water mass between Amami Island and the continental shelf of the East China Sea consists of main stream water, counter current water, gyration water and mixed water with coastal waters. 4. The maximum velocity of current in this waters was 139cm/sec. The volume transport was estimated approximately as $24.2\;\times\;10^6m^3/sec$. It was less than $33\;\times\;10^6m^3/sec$ in the region between Okinawa and continental shelf of the East China Sea. 5. Surface waters east of $29^{\circ}N\;Lat\;128^{\circ}E$ Long flows toward Amami Island, Okinawa Island, and Hachi Ju San Island, while those west of the region flow toward the Korea-strait, Cheju Island, coastal waters of Kyusyu, and the Pacific Ocean through Tokora Strait. The velocity of the current was estimated approximately as $0.3\~0.5$ miles per hour. 6. The bottom waters in the continental shelf break region flow toward the Korea Strait, Cheju Island and the coastal water of Kyusyu, while that of the continental shelf flows toward the Yellow Sea, 7, The characteristics of the Kuroshio water is changed remarkably by the mixing with the coastal water of China.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.1
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• pp.13-19
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• 2024

An analysis of the coastal water temperature in the Tongyeong waters, the eastern sea of the South Sea of Korea, revealed that the water temperature rose sharply before the typhoon made landfall. The water temperature rise occurred throughout the entire water column. An analysis of the sea surface temperature data observed by NOAA(National Oceanic and Atmospheric Administration) satellites, indicated that sea water with a temperature of 30℃ existed in the eastern waters of the eastern South Sea of Korea before the typhoon landed. The southeastern sea of Korea is an area where ocean currents prevail from west to east owing to the Tsushima Warm Current. However, an analysis of the satellite data showed that seawater at 30℃ moved from east to west, indicating that it was affected by the Ekman transport caused by the typhoon before landing. In addition, because the eastern waters of the South Sea are not as deep as those of the East Sea, the water temperature of the entire water layer may remain constant owing to vertical mixing caused by the wind. Because the rise in water temperature in each water layer occurred on the same day, the rise in the bottom water temperature can be considered as owing to vertical mixing. Indeed, the southeastern sea of Korea is a sea area where the water temperature can rise rapidly depending on the direction of approach of the typhoon and the location of high temperature formation.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.4
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• pp.306-317
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• 2014

This study has been executed to understand the additional and removal processes of nutrients in the Saemangeum Salt-water Lake, and discussed with other monthly-collected environmental parameters such as water temperature, salinity, dissolved oxygen, suspended solids, and Chl-a from 2008 to 2010. $NO_3$-N, TP, $PO_4$-P, and DISi showed the removal processes along with the salinity gradients at the surface water of the lake, whereas $NO_2$-N, $NH_4$-N, and Chl-a showed addition trend. In the bottom water all water quality parameters except $NO_3$-N appeared addition processes indicating evidence of continuous nutrients suppliance into the bottom layer. The mixing modelling approach revealed that the biogeochemical processes in the lake consume $NO_3$-N and consequently added $NH_4$-N and $PO_4$-P to the bottom water during the summer seasons. The $NH_4$-N and $PO_4$-P appeared strong increase at the bottom water of the river-side of the lake and strong concentration gradient difference of dissolved oxygen also appeared in the same time. DISi exhibited continuous seasonal supply from spring to summer. Internal addition of $NH_4$-N and $PO_4$-P in the river-side of the lake were much higher than the dike-side, while the increase of DISi showed similar level both the dike and river sides. The temporal distribution of benthic flux for DISi indicates that addition of nutrients in the bottom water was strongly affected by other sources, for example, submarine ground-water discharge (SGD) through bottom sediment.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.3
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• pp.224-232
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• 2000

Inorganic nutrient concentrations in relation to springtime physical parameters of the Yellow Sea were investigated during April 1996. Three major water masses, i.e., the Yellow Sea Warm Current Water (YSWC), Coastal Current Water (CCW) and Changjiang River Diluted Water (CRDW), prevailed in the study area. Water masses were vertically wel1 mixed throughout the study area, and nutrients were supplied adequately from bottom to surface layer. As result of ample nutrients supplied by vertical mixing together with progressed daylight condition, springtime phytoplankton blooms were observed, which was responsible for the depletion of inorganic nutrients in surface water column. Low nutrients concentration in bottom water of the central Yellow Sea (Stn. D9; nitrate: <2 ${\mu}$M, phosphate: <0.3 ${\mu}$) was associated with the entrance of YSWC which is characterized by high temperature and salinity. Influenced by runoff and vertical tidal mixing, CCW with high nutrient concentrations probably associated with China and Korea coastal waters with high nutrients concentration. For the local scale of inorganic nutrient distribution, nutrient transfers from coast to central areas were limited due to restriction imposed by tidal fronts (Stn. D6) and thus affected the horizontal nutrient profiles. Relatively high phytoplankton biomass was observed in the tidal front (Chl-${\alpha}$=12.38 ${\mu}$gL$^{-1}$) during the study period. Overall, the springtime nutrient distribution patterns in the Yellow Sea appeared to be affected by: (1) Large-scale influx of YSWC with low nutrient concentrations and CCW with high nutrient concentrations influenced by Korea and China coastal waters; (2) vertical mixing of water mass and phytoplankton distribution; and (3) local-scale tidal front as well as phytoplankton blooms alongthe tidal front.

• Korean Journal of Remote Sensing
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• v.33 no.2
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• pp.135-147
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• 2017

We, for the first time, estimated daily and monthly surface nitrogen dioxide ($NO_2$) volume mixing ratio (VMR) using three regression models with $NO_2$ tropospheric vertical column density (OMIT-rop $NO_2$ VCD) data obtained from Ozone Monitoring Instrument (OMI) in Seoul in South Korea at OMI overpass time (13:45 local time). First linear regression model (M1) is a linear regression equation between OMI-Trop $NO_2$ VCD and in situ $NO_2$ VMR, whereas second linear regression model (M2) incorporates boundary layer height (BLH), temperature, and pressure obtained from Atmospheric Infrared Sounder (AIRS) and OMI-Trop $NO_2$ VCD. Last models (M3M & M3D) are a multiple linear regression equations which include OMI-Trop $NO_2$ VCD, BLH and various meteorological data. In this study, we determined three types of regression models for the training period between 2009 and 2011, and the performance of those regression models was evaluated via comparison with the surface $NO_2$ VMR data obtained from in situ measurements (in situ $NO_2$ VMR) in 2012. The monthly mean surface $NO_2$ VMRs estimated by M3M showed good agreements with those of in situ measurements(avg. R = 0.77). In terms of the daily (13:45LT) $NO_2$ estimation, the highest correlations were found between the daily surface $NO_2$ VMRs estimated by M3D and in-situ $NO_2$ VMRs (avg. R = 0.55). The estimated surface $NO_2$ VMRs by three modelstend to be underestimated. We also discussed the performance of these empirical modelsfor surface $NO_2$ VMR estimation with respect to otherstatistical data such asroot mean square error (RMSE), mean bias, mean absolute error (MAE), and percent difference. This present study shows a possibility of estimating surface $NO_2$ VMR using the satellite measurement.

• 한국해양학회지
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• v.21 no.1
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• pp.13-24
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• 1986

The daily net primary production by phytoplankton in the southeastern sea of Korea in October 1985 ranged from 0.7 to 2.7 gCm$\^$-2/ d$\^$-1/ and averaged to be 1.3 gCm$\^$-2/ d$\^$-1/. Surface total chlorophyll ranged from 0.97 to 3.59mg chlm$\^$-3/. Primary production by nano-phytoplankton(〈20$\mu\textrm{m}$) ranged from 43 to 97% in the surface layer. Optimum light intensity(Iopt)was around 300 to 700${\mu}$Es$\^$-1/m$\^$-1/. Surface primary production from 9:00 to 15:00 h was evidently inhibited by strong light intensity beyond the Iopt. Phytoplankton near the base of euphotic zone(30-40m) showed extremely low Iopt suggesting adaptation to a low light environment. Since Iopt represents the history of light experience of phytoplankton at a given depth, the extent of variation in I of phytoplankton at different depth seems to be related to the in tensity of turbulence mixing in the surface mixed layer. From the present study, ammonium excretion by macrozooplankton (〉350$\mu\textrm{m}$) contributes from 3 to 19% of daily total nitrogen requirement by phytoplandton in this area. Calculation of upward flux of nitrate to the surface mixed layer from the lower layer, based on the simple diffusion model, approximates 3% of nitrogen requirement by phytoplankton. However, large portion of nitrogen requirement by phytoplankton remains unexplained in this area. In upwelling area near the coast, adjective flux might be the major source for the nitrogen requirement by phytoplankton. This study suggests that the major nitrogen source for the phytoplankton growth might come from the pelagic regeneration by nano-and micro-sized heterotrophic plandkon. Enhancement of primary production during the passage of the warm Tsushima Current is discussed in relation with nutrient dynamics and hydrlgraphic processes in this area.

• Korean Journal of Environmental Biology
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• v.18 no.4
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• pp.425-440
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• 2000

The physico-chemical characteristics and the concentrations of chlorophylls of coastal seawater were investigated to know the seasonal variations of biological oceanographic environments in the Islands of Ullungdo(U) and Dokdo(D). The samplings of sea water according to different depths were performed four seasons (May, June, August and November) in five stations along the coast of Ullungdo Island and 3 times (June, August and November) in three stations around the coast of Dokdo Island. The seasonal variations of sea water temperature showed that the formation of thermocline in August was distinct in comparison to the other seasons. The sea water in the surface was influenced by low temperature-high salinity in May and with high temperature-low salinity in the investigated area. The amount of seston was high in May (5.3-15.0mg/l) and was low in August (1.4-4.9mg/l) in ullungdo island. for the nutrients or sea water in Ullungdo Island, the concentrations of nitrate and ammonium were higher than Dokdo Island (nitrate-max. of U in August : 0.10-11.50$\mu\textrm{g}$/1, max. of D in August : 2.92-8.10$\mu\textrm{g}$/l : ammonium-max. of U in November : 14.18-20.69$\mu\textrm{g}$/l, max. of D in June : 0-1.78 $\mu\textrm{g}$/l). The high concen-tration of chlorophylls showed on the deeper layer from 30 m to 50 m in August (U 30 m : 0.85$\mu\textrm{g}$/l ; D 50m : 1.02 $\mu\textrm{g}$/l), while the concentrations of chlorophylls were even in May, June and November in the deeper layer of surface layer. In conclusion, the establishment of thermocline in deeper area of the euphotic layer in August was a trigger far the development of phytoplankton, while the complex physico-chemical system by diverse currents and vertical mixing of sea water in the area induced the even distribution of phytoplankton in both epilimnion and hypolimnion in May, June and November.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.3
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• pp.177-184
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• 1991

We have investigated geographical distribution and physico-chemical properties of water masses or water types at mid-bottom depth in the neighbouring sea of Cheju Island in August 1986. In 50m layer the Yellow Sea Bottom Cold Water(YSBCW) below $12^{\circ}C$ was observed in the northwestern area of Cheju Island, while the Tsushima Warm Water(TWW) with relatively high temperature$(>16^{\circ}C)$ and salinity more than 34.0 in its southeastern area extended as far as the coast of about 15km. Also, 50m layer at the outside stations of its southwestern area indicated relatively cold water temperature$(11-30^{\circ}C)$, probably due to southward transport of the Yellow Sea Bottom Cold Water(YSBCW . The Yellow Sea Warm Water(YSWW), the mixed water of the YSBCW and the TWW, ranged $13^{\circ}C$ to $16^{\circ}C$ in water temperature and was appeared mainly in the coastal and intermediate area of Cheju Island. And the relatively cold water in the southwestern area and the Tsushima Warm Water were more extensively distributed in 50m layer than the deeper layer. Horizontal distributions of nitrate and phosphate showed a pattern similar to that of water temperature. As it were, the Yellow Sea Bottom Cold Water had the highest concentration of nutrients, while southwestern outside stations had the lowest nutrient contents. Especially, the concentration of nitrate in the latter was remarkably low compared with the value at the other stations. It may be attributed to intensive vertical mixing by collision of the northward driven Tn with the southward driven YSBCW. Also, it was particular that the Tsushima Warm Water indicated relatively high silicate content corresponding to that of the Yellow Sea Bottom Cold Water. Based on the data of $\Delta Si/\Delta P$ ratio, it seems that the mid-bottom waters in this study area are younger than the surface or intermediate water in the Korean East Sea.