• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
• /
• pp.344-347
• /
• 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.

• 대한원격탐사학회지
• /
• 제16권4호
• /
• pp.315-325
• /
• 2000

Observations were made to validate ocean color algorithms in the Ulleung Basin, East Sea in May 2000. Small scale and meso-scale surveys were conducted for the validation of ocean color products (nLw: normalized water-leaving radiance and chlorophyll concentration). There were discrepancies between SeaWiFS and in situ nLw showing the current aerosol models of standard SeaWiFS processing software are less than adequate (Gordon and Wang, 1994). Applying the standard SeaWiFS in-water algorithm resulted in an overestimation of chlorophyll concentration. This is because that CDOM absorption was higher than the estimated chlorophyll absorption. TSS concentration was also high. Therefore, the study region deviated from Case 1 waters. The source of these materials seems to be the entrainment of coastal water by the Tsushima Warm Current. Study of the bio-optical properties in other season is desirable.

• Ocean and Polar Research
• /
• 제35권2호
• /
• pp.157-170
• /
• 2013

We investigated the seasonal succession of phytoplankton assemblages in the eastern part of the South Sea of Korea in relation to surface water masses. The study areas are under the direct influence of the Tsushima Warm Current (TCW) throughout the whole year, with its strength known to be seasonally variable. The region is also influenced by coastal waters (CW) driven from the South Sea of Korea and East China Sea, particularly in summer, as indicated by low salinity in the surface water. Nutrient property of the TCW can reveals whether the origin of the TCW is the nutrient-rich Kuroshio Current or the oligotropic Taiwan Warm Current. Surface chlorophyll-a (Chl-a) concentrations displayed a large seasonal variation for all stations, with high values found in spring and autumn and low values in summer and winter. At station M (offshore) and P (intermediate location between M and R), Chl-a concentrations in October were higher than those in March, when spring bloom normally occurs. This may be related to deeper mixed layer depths in October. Diatoms dominated under conditions of high nutrient supply in which Chaetoceros spp. and Skeletonema costatum-like spp. were abundant. S. costatum-like spp. dominated at stations R (onshore station) and P in December when there was greater nutrient supply, especially of phosphate. Flagellates and dinoflagellates dominated at all three stations after diatoms blooms. Dominant species were Scrippsiella trochoid in April and Ceratium furca in October at station R, and Gyrodinium spp. and Gymnodinium spp. at station M during summer, when the effect of the oligotropic Taiwan Warm Current and the oligotropic coastal water from East China Sea were strong. Redundancy analysis showed clear seasonal successions in the phytoplankton community and environmental conditions, in which both principal components 1 and 2 accounted for 69.6% of total variance. Our results suggested that environmental conditions seemed to be determined by the origin of the TCW and the relative seasonal strength of the water masses of the TCW and CW, which may affect phytoplankton growth and compositions in the study area.

• Fisheries and Aquatic Sciences
• /
• 제11권1호
• /
• pp.41-49
• /
• 2008

Internal waves and internal tides occur frequently along the eastern coast of Korea. During the spring-tide period in April 2003, the East Korean Warm Current (EKWC) flowed near the Korean East Coast Farming Forecast System (KECFFS; a moored oceanographic measurement system), creating a strong thermocline at the intermediate layer. Weakened stratification and well-mixed water appeared frequently around the KECFFS, with duration of approximately 1 day. The results suggest the following scenario. Baroclinic motion related to the internal tide generated high frequency internal waves around the thermocline. The breaking of those waves then created turbulence around the thermocline. After well-mixed water appeared, a current component with perpendicular direction to the EKWC appeared within the inertial period. The change in stratification around the KECFFS locally broke the geostrophic balance as a transient state. This local vertical mixing formed an ageostrophic current within the inertial period.

• Journal of the korean society of oceanography
• /
• 제34권3호
• /
• pp.133-143
• /
• 1999

We carried out simultaneous and long-time observations of currents across the western channel of the Korea Strait during the period of May, 1994 to September, 1996 in order to understand the spatial and temporal variability of tidal and nontidal currents in the Strait. Results show that currents in the Strait are quite variable in space and time, and they largely consist of mean current and diurnal and semidiurnal tidal currents of about equal magnitudes. The mean currents include the Tsushima Current and the Korea Strait Undercurrent at the center of the channel. The former occupies the upper two-thirds and the latter the lower one-third of the water column. The semidiurnal and diurnal currents are largely rectilinear in the direction of NE-SW and their amplitude variation across the channel appears to be small. However, the diurnal currents at some locations show rotational characteristics with significant nontidal effects. The station close to the Korean coast leads the phase and the phase difference of the semidiurnal current across the channel appears to be less than half an hour while that of the diurnal current is over five hours.

• 한국수산과학회지
• /
• 제30권6호
• /
• pp.1044-1055
• /
• 1997

To find out generating mechanism of eddies in the polar frontal zone of the East Sea, we carried out a series of numerical experiments using the nonlinear $1^{1/2}-layer$ model allowing the effect of the polar front. We assumed the polar front at about $39^{\circ}N$ in zonal direction with the cold water region in the northern part and the warm water region in the southern part of the model ocean. To examine the effect of the frontal motion without the influence of the Tsushima Current from the beginning of the geostrophic adjustment, the initial state of the model ocean was assumed motionless. Eastward current was caused by the geostrophic adjustment process in the polar frontal zone that induced a steady northward coastal current along the Korean coast to satisfy the mass continuity. The overshooting of this coastal current acted as an initial disturbance of the zonal flow field which caused meanders and eddies. The spatial scales of eddies were in good agreement with the baroclinic instability theory.

• 한국수산과학회지
• /
• 제22권5호
• /
• pp.294-305
• /
• 1989

한국 근해의 서남해 및 동지나해에 있어서 최근 16개년간($1970\~1985$)의 안강망에 의한 병어어획통계자료로 부터 병어류의 분포 및 회유와 해양환경에 따른 어황을 살펴본 결과는 다음과 같다. 병어류의 주요 어장은 제주도와 양자강하구를 잇는 선상에 위치한 대양자사퇴역으로, 병어류가 어획되었던 분포역은 전면적의 약 $11\%$에 해당하는 14개 해구에서 전어획량의 약 $70\%$를 차지하고 있었다. 전해구에 걸쳐 어획량의 변동 계수는 0.01 미만이었으며, 14개 주요 어장의 변동 계수는 $0.001\~0.003$으로 특히 작았다. 또한, 이 해역은 춘계부터 추계까지 황해난류의 유입이 뚜렷하며, 중국대륙연안수와 황해저층냉수 및 쓰시마 난류 사이에 뚜렷한 전선을 형성하고 있는 혼합수역이었다. 병어류는 쓰시마 난류와 황해저충냉수의 소장에 따라 남북회유를 한다. 즉, 하계에는 황해북부로, 동계에는 동지나해 중부이남의 월동장으로 회유한다. 병어류 어획 수형의 최대빈도범위는 수온 $10\~12^{\circ}C$ 염분 $32.4\~33.4\%_{circ}$로, 이 범위에서 어기별 총 어획량의 $70\%$ 이상을 차지하였으며, 한어기와 성어기에 따른 최다어획 수형빈도범위는 차이가 없었다.

• 한국해양학회지:바다
• /
• 제8권2호
• /
• pp.94-110
• /
• 2003

본 연구는 Topex/Poseidon 고도계 자료(1992∼2000년, 286 cycles)를 사용하여 동해의 해면고도의 시공간적 변동 특성과 구조를 규명하였다. 분석을 위하여 객관적 적합보간법을 이용하여 격자구조의 해면이상치(SSHA)자료를 생성하였으며, 스펙트럼 분석과 경험직교함수 분석을 하였다. SSHA분포는 동해 극전선 해역을 중심으로 남쪽해역과 북쪽해역으로 구분이 되며, 남쪽해역은 쓰시마난류의 영향을 받아 SSHA의 변동폭이 크고, 북쪽해역은 상대적으로 작다. 동해에서의 시공간적 변동 특성은 5개의 경험직교함수로서 특징 지워지며 총분산의 85% 이상을 설명할 수 있었다 제 1모드는 동해의 전역의 SSHA의 계절 및 년간 변동을 지배하며 총분산의 72.3%로 우세하다. 제 2-5 모드들은 상대적으로 적은 분산을 설명하고 있으며(약 14%), 주로 쓰시마난류, 동한난류와 관련된 해류의 영향에 의한 연안해역의 변동과 극전선역의 사행과 관련된 변동 및 중규모 소용돌이와 관련된 변동으로 파악되었다. 유의한 스펙트럼을 보이는 주기는 0.5년 1년, 2.5년, 3.3년 등이었다.

• 한국해양학회지:바다
• /
• 제27권1호
• /
• pp.1-16
• /
• 2022

질산염은 대한해협의 생태계 및 어업에 있어 중요한 영향을 준다. 관측을 기반으로 한 선행연구들은 해류가 질산염 수송에 중요한 영향을 줄 가능성을 제시하였다. 그러나 해류에 의한 질산염 수송과 생지화학적 요인에 의한 질산염 유출입의 정량적인 평가에 대한 연구는 없었다. 본 연구에서는 해류와 생지화학학적 요인에 대한 질산염 유출입의 계절 및 공간적인 변화를 2011년부터 2019년까지 물리-생지화학 결합 모델을 수행하여 살펴보았다. 모델 결과 분석을 통해 대한해협은 해류로 인해 질산염이 공급되며 공급된 질산염은 식물 플랑크톤의 섭식에 의해 소비됨을 알 수 있었다. 해류에 의한 질산염 수송량 중 제주도와 큐슈지역을 통과하는 해류에 의한 질산염 수송이 가장 컸으며 제주해협을 통과하는 해류에 의한 수송량은 이보다 1/3배 적었다 대한해협 서수도로 유출되는 질산염 수송량은 동수도로 유출되는 양보다 2배 더 많았다. 월 평균 질산염 순 유출입을 살펴보면 제주해협과 제주도와 큐슈를 통과하는 해류로 인해 공급된 질산염이 1월을 제외한 연중 대한해협에서 생지화학적 요인에 의해 순 유출되고 있었고, 이로 인해 대한해협을 통과하여 동해로 유입되는 질산염 수송량이 감소함을 알 수 있었다.

• Journal of the korean society of oceanography
• /
• 제38권3호
• /
• pp.87-100
• /
• 2003

The monthly observations of hydrography in the Cheju Strait from September 1995 to June 1998 show that the Cheju Strait is occupied mostly by Tsushima Current Water in winter and coastal waters in summer. In summer, the Yangtze Coastal Water appears in the upper layer and cold water in the lower layer. Especially, the Yellow Sea Bottom Cold Water appears in August 1997, and the clockwise flow of warm water along the northwestern coasts of Cheju Island is disturbed by an eastward expansion of the cold water from the northwest. The cold water expansion seems to be partly associated with strong southeasterly winds. Current measurements in the Cheju Strait suggest that there exists steady eastward barotropic component of about 5 cm/sec, which corresponds to 0.2 Sv barotropic transport in the Cheju Strait. Geostropic transport (baroclinic component) ranges from 0.1 Sv in winter to 0.4 Sv in summer. By adding the barotrophic component of 0.2 Sv, the total transport varies from 0.3 Sv to 0.6 Sv, which is consistent with previous estimations. The transport increase in summer seems to be caused by the expansion of coastal water to the Cheju Strait.