• 한국해양학회지
• /
• v.30 no.2
• /
• pp.91-115
• /
• 1995

Air-sea heat fluxes in the East Sea were estimated from the various ship's data observed from 1961 to 1990 and the JMA buoy #6 data from 1976 to 1985. The oceanic heat transport in the sea was also determined from the fluxes above and the heat storage rate of the upper layer of 200m from the sea surface. In winter, The incoming solar radiation is almost balanced with the outgoing longwave radiation. but the sea loses her heat through the sea surface mainly due to the latent and sensible heat fluxes. The spatial variation of the net surface heat flux is about 100 Wm/SUP -2/, and the maximum loss of heat is occurred near the Tsugaru Strait. There are also lots of heat losses in the southern part of the East Sea, Korea Strait and Ulleung Basin. Particularly, the heat strong loss in the south-western part of the sea might be concerned with the formation of her Intermediate Homogeneous Water. In summer, the sea is heated up to about 120∼140 Wm/SUP -2/ sue to strong incoming solar radiation and weak turbulent heat fluxes and her spatial variation is only about 20 Wm/SUP -2/. The oceanic heat flux is positive in the southeasten part f the sea and the magnitude of the flux is larger than that of the net surface heat flux. This shows the importance of the area. In the southwestern part of the sea, however, the oceanic heat flux is negative. This fact implies cold water inflow, the North Korean Cold Water. The sigh of net surface heat flux is changed from negative to positive in March and from positive to negative in September. The heat content in the upper surface 200 m from the sea surface reaches its minimum in March and maximum in October. The annual variation of the net surface heat flux is 580 Wm/SUP -2/ in southwestern part of the sea. The annual mean values of net surface heat fluxes are negative, which mean the net heat transfer from the sea to the atmosphere. The magnitude of the flux is about 130 Wm/SUP -2/ near the Tsugaru Strait. The net surface fluxes in the Korea Strait and the Ulleung Basin are relatively larger than those of the rest areas. The spatial mean values of surface heat fluxes from 35$^{\circ}C$ to 39$^{\circ}$N are 129, -90, -58, and -32 Wm/SUP -2/ for the incoming solar radiation, latent hear flux, outgoing longwave radiation, and sensible heat flux, respectively.

• Korean Journal of Ichthyology
• /
• v.11 no.2
• /
• pp.155-162
• /
• 1999

To study the distribution of larva and juvenile of the sand eel, Ammodytes personatus in the Kangwon coastal, samples were collected by the larva net (RN 80 net) and small drag net at 60 stations from January 1996 to December. Appearance season of larva and juvenile of sand eel was appeared untill the January to June in the Kangwon-do coast, and the densities of them were high in June. Appearance phase, length frequency distribution of larva and juvenile of sand eel were distributed that the average standard length 10.0~30.0mm in the temperature range of $5.0{\sim}6.0^{\circ}C$ at the January to March, and April to June occurred the average standard length 40.0~80.0 mm in the temperature range of $7.2{\sim}12.0^{\circ}C$. It was distributed in southern part of Kangwon-do coast until the February to March 1996. And association of the sand eel migrated to the northern and middle part of Kangwon-do coast at April when surface water temperature was higher than $7.2^{\circ}C$. It was considered that the migration of the abundance larva and juvenile of sand eel in this area is mainly affected by the water temperature.

• The Korean Journal of Quaternary Research
• /
• v.5 no.1
• /
• pp.15-31
• /
• 1991

A total of 90 surface sediment samples, collected from the continental margin area bordering east and southeast coast of Korea, were subject to the geochemical analyses with the aim of filling the gap in our knowledge of this environment. The analyzed items included the major elements (Al, Fe, Mg, Ca, K, Na, p and Mn), organic carbon, and some trace metals (Ba, Co, Cu, Sr and Zn). The sediment grain-size exerted a predominant influence on the contents of most elements, with the exceptions of Ca, K, Sr and Ba. The Ca and Sr contents, being closely interrelated each other, were mainly controlled by the calcium carbonate content. The K content, on the other hand, appeared to be influenced by both illite and feldspar. The Ba content showed a certain relationship with that of K, suggesting a common source of these two elements; potassium feldspar. The R-mode factor analysis result also reaffirmed the above-mentioned controlling factors on the sediment geochemistry. The grain-size dependency of trace metals obscures their areal distribution pattern from the total contents. However, with the metal/aluminum ratios we could differentiate the subtle difference in the metal enrichment. Hence, sediments of the southern coastal area appear to receive some anthropogenic inputs of metals, though the effect is still negligible.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.18 no.3
• /
• pp.261-265
• /
• 1985

Limanda yokohamae was studied on its growth, age at maturity, fecundity and survivorship, based on the specimens off the southeastern coast of Korea from December 1983 to November 1984. The total lengths at the formation of annulus on the otolith were back-calculated. The age at the first reproduction is 2yrs in both sexes. Fecundity was estimated to be $121{\times}10^3{\sim}429{\times}10^3$. Annual survival rate is 0.435 in female and 0.335 in male.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.21 no.3
• /
• pp.139-144
• /
• 1988

The vertical distribution of eggs and larvae of anchovy. Engraulis japonica were studied based on ichthyoplankton and the temperature distribution in the southwestern part of the Sea of Japan off Korea during the summer of 1985 and 1986. Thermoclines occurred at the surface layer in the coastal area and at the sub-surface layer in the offshore area in the early summer of 1985. However, they occurred at the surface layer throughout the summer of 1986. Anchovy eggs and larvae were abundant in the offshore in 1985 and in the coastal area in 1986. It seems that the spawning ground of anchovy in 1985 shifted to the offshore owing to the sloping of thermoclines. According to the distribution layer of anchovy eggs by developmental stage, the eggs in the early developmental stage were abundant at $0\~30m$ layer about 06:00. But the eggs in the late developmental stage were abundant at $30\~100m$ loom layer about 24 : 00. These results suggest that anchovy spawn at the $0\~30m$ layer at night and eggs tend to sink to the $30\~100m$ layer in the course of development.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.40 no.3
• /
• pp.160-166
• /
• 2007

The coarse deposit with a lower mud content adjacent to the shelf of the southern East Sea is probably a "relict" sediment deposited in response to a lower stand of sea level during the Pleistocene. The sediment that developed on the slope and in the deep sea was river-borne primarily and was secondarily reworked or redistributed by the Tsushima Warm Current from the East China Sea. The clay mineralogy of the area suggests various sources of fine-grained sediment from adjacent rivers, the Korea Strait, volcanic material from Ulleung Island, and the Japan coast. Massive sand, bioturbated mud, homogeneous mud, and laminated mud were the dominant facies found in the core sediments from the study area. The massive sand was mainly volcanic ash from an eruption on Ulleung Island (9300 yr BP) and consisted of colorless pumiceous glass and a black scoriaceous type. The sedimentation rates on the slope, based on the Ulleung-Oki ash layer, were about 10cm/ky higher than in the basin. Other than the coarse-grain sediment, the mean size of the fine sediment dominating the bioturbated and homogeneous muds in the basin and the laminated mud on the slope was 6-10 phi. This indicates a difference in the major sedimentary process: hemipelagic sedimentation in the Ulleung Basin and mass flow deposition, such as turbidite, on the slope of the southern East Sea.

• Ocean and Polar Research
• /
• v.40 no.3
• /
• pp.115-125
• /
• 2018

Production from copepodite IV to adult of two euchaetid species Euchaeta plana and Paraeuchaeta russelli was measured at the southeastern sea of Korea from April to November, 2014. The mean density was $2.0ind\;m^{-3}$ for E. plana and $4.1ind\;m^{-3}$ for P. russelli, with the high contribution of copepodite V to total density. The densities of total individuals, adult females and eggs were highest in November for both species. The mean egg production rate (EPR) was $1.7eggs\;female^{-1}\;d^{-1}$ for E. plana and $3.1eggs\;female^{-1}\;d^{-1}$ for P. russelli. Both of them showed the highest EPR in September but zero EPR in summer. The mean weight-specific EPR was $0.038d^{-1}$ for E. plana and $0.079d^{-1}$ for P. russelli. The mean total production rates of E. plana and P. russelli were $5.3{\mu}g\;C\;m^{-3}\;d^{-1}$ and $17.8{\mu}g\;C\;m^{-3}\;d^{-1}$, respectively, with the largest production in November. The mean Production/Biomass ratio was $0.06d^{-1}$ for E. plana and $0.07d^{-1}$ for P. russelli, with its peak in September for both. The total production of E. plana and P. russelli was positively correlated with the density of a copepod Oncaea venusta, rather than chl-a concentration, indicating that the two copepods might be carnivores. This study evaluates the contribution of euchaetids to the copepod community in the southeastern sea of Korea.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.13 no.2
• /
• pp.89-105
• /
• 2008

Sea level and atmospheric pressure data of 1999-2005 from four stations along the Korean east coast were analyzed to understand the sea level variability and its causal mechanism. The results of the wavelet and the auto-spectrum analyses indicate that the sea level fluctuations of 3-17 day period are statistically significant at the 95% confidence level, especially in spring to early summer. In this period, the coherency between the sea levels and the atmospheric pressures in a cross-spectrum is high, implying the importance of an inverted barometric effect in generation of the sea level fluctuations. To learn about the sea level variability, the cross-spectrum analyses were applied between the sea levels of the adjacent stations. The results show a case of southward phase propagations along the coast, as in 1999, 2003 and 2005, and an another case of no progressive phase lags between the stations, as in 2000-2002, and 2004. The phase speed in the former case is 12-15 m/s, which is a commonly observed phase speed of coastal Kelvin waves. Generation of such fluctuations seems to be related to low pressure cells developed in the Asian continent in spring and summer and moving eastward over the coastal region north of the stations. The latter case of no progressive phase lag, however, occurs when the low pressure cells developed in the continent move along the region south of the stations. In this case, the northeastward phase propagation with a speed of 5-8 m/s is observed along the southwestern coast of Japan.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.31 no.1
• /
• pp.45-55
• /
• 1998

Phytoplankton community and primary productivity have been investigated in a fall season in the southern coastal waters of the last Sea, Korea. A strong thermocline formed at the 20\~60\;m$ layer and a cold water mass also existed in the bottom around Yong-il Bay. The offshore of the surveyed area was likely to be influenced by relatively warmer water, whereas the inshore represented Higher primary productivity with lower water temperature and lower salinity. A total of 133 species of phytoplankton occurred, representing 107 spp. of diatom, 23 spp. of dinoflagellate 3 spp. of silicoflagellate. Skeletonema costatum and Asterionellepsis glacialis were most predominant with more than $30\%$ dominance ratio, while Leptocylindrus danicus was also dominant at all transect lines. Standing crops of phytoplankton ranged from $2.7{\times}10^3\;to\;141.6{\times}10^3\;cell^{\ell-1}$. Chlorophyll a concentration varied with stations and layers, but the $30\~50$ m layer showed maximun with about $1.18{\mu}g{\ell}^{-1}$ rather than at the surface layer. It is believed that the maximun in standing crops and chlorophyll of phytoplankton formed at the $20\~50$ m layer above the thermocline during the survey. Phytoplankton primary productivity ranged from 0.32 to 3.04 mgC $m^{-3}\;hr^{-1}$, showing higher at the inshore than at the offshore. The range of integrated primary productivity was $263.3\~1085.5 mgC\;m^{-2}\;day^{-1}$ for the euphotic layer. Photosysthesis rates varied with the range from 0.76 to 8.04 mgC mgChl $\alpha^{-1}\;hr^{-1}$. Phytoplankton photosynthesis at the inshore was saturated at lower irradiance ($15\~35\%$ of surface) and showed higher efficiency, Thus, it revealed that the phytoplankton community probably adapted to the middle of euphotic layer because the depth of mixing layer became thinner due to the formation of thermocline.

• Korean Journal of Ichthyology
• /
• v.22 no.3
• /
• pp.154-161
• /
• 2010

The reproductive ecology of the cardinalfish Apogon lineatus was examined using 4,300 specimens collected monthly from January to December 2006 in the coastal waters of Gori, Korea. Specimens ranged in standard length (SL) from 2.1 to 8.6 cm. They were distributed more in surface areas during summer and autumn and more on bottom areas during spring and winter. The gonadosomatic index (GSI) of females was highest in September and decreased until December, with the spawning season lasting from August to October. The monthly ratio of female to male did not significantly differ (${\chi}^2$-test, p>0.05). The size of 50% maturity was estimated at 5.43 cm SL and all females more than 7.0 cm SL were sexually mature. A. lineatus is a multiple spawner, spawning on more than one occasion in a single spawning season. The maximum egg diameter was 0.65 mm. Fecundity (F) ranged from 8,555 to 20,084 eggs, with a mean of 15,038 eggs. The relationship between fecundity and standard length was estimated as F=$334,851\;SL^{1.9876}$ ($R^2$=0.53). The relationship between fecundity and body weight(BW) was estimated as F=7,167.6 Ln (BW)-2,198.1 ($R^2$=0.33).