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1.
Closed loop mesoscale eddies were identified and tracked in the Ulleung Basin of the southwestern Japan/East Sea (JES) using the winding-angle (WA) methodology, for mapping the absolute geostrophic currents into surface streamlines of flow. The geostrophic velocity used here was the sum of the Archiving, Validation and Interpretation of Satellite Oceanographic data (AVISO), time variable velocity and the 1992–2007 mean geostrophic velocity. Local sampling bias was removed using the drifter observations. This WA methodology of deriving the Lagrangian path lines that drifters followed over a 7-day period was validated by individual drifter tracks and it demonstrated closed looping eddy motions. The WA method demonstrated that less than 6% of the closed streamlines appeared when drifters did not show a closed loop in their vicinity, compared to 30% of the excess detection rate by the Okubo–Weiss method of locating closed loop structures. Three groups of eddies were identified: (1) Coastal Cold and Warm Eddies, which appeared in the area between the coast of southern Korea and the East Korean Warm Current (EKWC), when a southward coastal current was present, (2) Frontal Cold and Warm Eddies, which were formed in the region of the seaward extension of the meandering EKWC, north of Ulleung Island and (3) Ulleung Warm Eddies (UWE) and Dok Cold Eddies (DCE), which appeared during meanders of the EKWC, in the Ulleung Basin. No seasonal concentration for eddy generation and eddy population was found. The average radius of eddies was about 38–60 km. These were born, moved in an erratic pattern and then died in the vicinity where the EKWC separated from the coast and formed a large meander. The time-mean large meander formed meridionally concentrated bands of positive and negative relative vorticity. The cyclonic (cold) eddies tend to reside within the band of positive time-mean relative vorticity, and the anticyclonic (warm) eddies reside within the bands of negative relative vorticity. Six UWE and four warm eddies, in the Yamato Basin (about 10% of warm eddies), were sustained longer than a year. Because the large meander of the EKWC appeared to be controlled by topography, and the JES is a nearly enclosed basin with rapid flow-out to the east through the narrow Tsugaru Strait, there was little eddy energy propagation to the west. The warm eddies in the southwestern part of the JES appeared to be interacting very locally with the mean flow.  相似文献   

2.
A review is made of circulation and currents in the southwestern East/Japan Sea (the Ulleung Basin), and the Korea/Tsushima Strait which is a unique conduit for surface inflow into the Ulleung Basin. The review particularly concentrates on describing some preliminary results from recent extensive measurements made after 1996. Mean flow patterns are different in the upstream and downstream regions of the Korea/Tsushima Strait. A high velocity core occurs in the mid-section in the upstream region, and splits into two cores hugging the coasts of Korea and Japan, the downstream region, after passing around Tsushima Island located in the middle of the strait. Four-year mean transport into the East/Japan Sea through the Korea/Tsushima Strait based on submarine cable data calibrated by direct observations is 2.4 Sv (1 Sv = 106 m3 s−1). A wide range of variability occurs for the subtidal transport variation from subinertial (2–10 days) to interannual scales. While the subinertial variability is shown to arise from the atmospheric pressure disturbances, the longer period variation has been poorly understood.Mean upper circulation of the Ulleung Basin is characterized by the northward flowing East Korean Warm Current along the east coast of Korea and its meander eastward after the separation from the coast, the Offshore Branch along the coast of Japan, and the anticyclonic Ulleung Warm Eddy that forms from a meander of the East Korean Warm Current. Continuous acoustic travel-time measurements between June 1999 and June 2001 suggest five quasi-stable upper circulation patterns that persist for about 3–5 months with transitions between successive patterns occurring in a few months or days. Disappearance of the East Korean Warm Current is triggered by merging the Dok Cold Eddy, originating from the pinching-off of the meander trough, with the coastal cold water carried Southward by the North Korean Cold Current. The Ulleung Warm Eddy persisted for about 20 months in the middle of the Ulleung Basin with changes in its position and spatial scale associated with strengthening and weakening of the transport through the Korea/Tsushima Strait. The variability of upper circulation is partly related to the transport variation through the Korea/Tsushima Strait. Movements of the coastal cold water and the instability of the polar front also appear to be important factors affecting the variability.Deep circulation in the Ulleung Basin is primarily cyclonic and commonly consists of one or more cyclonic cells, and an anticyclonic cell centered near Ulleung Island. The cyclonic circulation is conjectured to be driven by a net inflow through the Ulleung Interplain Gap, which serves as a conduit for the exchange of deep waters between the Japan Basin in the northern East Sea and the Ulleung Basin. Deep currents are characterized by a short correlation scale and the predominance of mesoscale variability with periods of 20–40 days. Seasonality of deep currents is indistinct, and the coupling of upper and deep circulation has not been clarified yet.  相似文献   

3.
Circulation in the upper and the intermediate layer of the East Sea is investigated by using a fine resolution, ocean general circulation model. Proper separation of the East Korean Warm Current from the coast is achieved by adopting the isopycnal mixing, and using the observed heat flux (Hirose et al., 1996) and the realistic wind stress (Na et al., 1992). The simulated surface circulation exhibits a remarkable seasonal variation in the flow patterns of the Nearshore Branch, the East Korean Warm Current and the Cold Currents. East of the Oki Bank, the Nearshore Branch follows the isobath of shelf topography from late winter to spring, while in summer and autumn it meanders offshore. The Nearshore Branch is accompanied by cyclonic and anticyclonic eddies in a fully developed meandering phase. The meandering and the eddy formation of the Nearshore Branch control the interior circulation in the Tsushima Current area. A recirculation gyre is developed in the region of the East Korean Warm Current in spring and grown up to an Ulleung Basin scale in summer. A subsurface water is mixed with the fresh surface water by winter convection in the northeastern coastal region of Korea. The well-mixed low salinity water is transported to the south by the Cold Currents, forming the salinity minimum layer (Intermediate Water) beneath the East Korean Warm Current water. The recirculation gyre redistributes the core water of the salinity minimum layer in the Ulleung Basin. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

4.
The northward intruding eddy along the East coast of Korea   总被引：5，自引：0，他引：5  
The current structures and their seasonal variations in the East Korean Warm Current (EKWC) region, which plays a significant role in the northward transport of warm and saline waters, were described by combining the sea surface temperature (SST) data of consecutive satellite inferred (IR) images and hydrographic data. The SST patterns in winter-spring clearly showed that the small meander of thermal front originating from the Tsushima/Korea Strait formed close to the Korean coast and grew an isolated warm eddy with horizontal dimension of order 100 km. Such warm eddy began to intrude slowly northward from spring to summer. At that time, interactions with neighboring synoptic warm eddy [Ks] around the Ulleung Basin were found to have strongly influence the movement of the intruding eddy and its structural change. In autumn, after the northward movement stopped at the north of eddy [Ks], the relative stable northward current along the Korean coast were formed. The evidence from observational results does not support a persistent branching of the EKWC from the Tsushima/Korea Strait, but a seasonal episodic supply of warm and saline waters due to the northward intruding eddy process described above.  相似文献   

5.
Absolute geostrophic velocities were calculated along TOPEX/Poseidon (T/P) groundtracks located in the Ulleung Basin of the southwestern Japan/East Sea (JES) from a combined analysis of nearly a decade of T/P data and two years of pressure-gauge-equipped inverted echo sounder (PIES) data obtained during the United States Office of Naval Research’s JES Program. Geostrophic velocities have been calculated daily for the Ulleung Basin from June 1999 to July 2001 from a three-dimensional mapping of temperature and salinity produced by PIES data interpreted via the Gravest Empirical Mode (GEM) technique combined with the Navy’s Modular Ocean Data Assimilation System (MODAS). These velocities were then used to convert T/P velocity anomalies to absolute velocities for the T/P time period of 1993 to 2002. Current intensities and variabilities associated with the East Korean Warm Current, Ulleung Warm Eddy, and Offshore Branch are examined. Spatial and temporal variations of the sea surface circulation are strong. Intensification of the currents generally occurred during the fall season. The flow pattern in individual years differed greatly from year to year and differed from climatology in important qualitative ways.  相似文献   

6.
Numerical experiments were performed in order to investigate the effects of variations of the transport through the Korea/Tsushima Strait, an inlet of the Japan/East Sea, on the upper layer circulation in the JES based on a 10-month transport observation from May 1999 to March 2000 (Perkins et al., 2000). All external forcings to the model were annual mean fields, except the transport variation through the Korea Strait. In the experiments where the periodic variation of the transport repeated continuously sinusoidally by several periods, strong variability of sea surface height (SSH) was detected in the region extending from the Korea Strait to the Japanese coast due to the geostrophy of the buoyancy forcing at the Korea Strait. The region along the Korean coast is more sensitive to the long-term variations than the short-term (≤60-day period) ones. In two experiments forced by realistic and monthly mean transport, the difference of rms of sea surface height was largest at the Japanese coast and relatively large at the East Korean Warm Current separation region (128∼130°E, 39∼41°N) and to the east of Yamato Rise. The distribution of difference of eddy kinetic energy at 100 m depth between the two experiments was similar to that of the rms of SSH. In the distributions of mean SSH and mean kinetic energy at 100 m depth the realistic transport invokes eddy variability to interact with mean current resulting in the changes of the mean SSH and the mean kinetic energy at the East Korean Warm Current separation region, but it does not produce conspicuous changes in the mean fields of entire JES compared with the mean fields forced by the seasonal transport.  相似文献   

7.
Deep circulation in the southwestern East/Japan Sea through the Ulleung Interplain Gap (UIG), a possible pathway for deep-water exchange, was directly measured for the first time. Five concurrent current meter moorings were positioned to effectively span the UIG between the islands of Ulleungdo to the west and Dokdo to the east. They provided a 495-day time series of deep currents below 1800 m depth spanning the full breadth of the East Sea Deep and Bottom Water flowing from the Japan Basin into the Ulleung Basin. The UIG circulation is found to be mainly a two-way flow with relatively weak southward flows directed into the Ulleung Basin over about two-thirds of the western UIG. A strong, persistent, and narrow compensating northward outflow occurs in the eastern UIG near Dokdo and is first referred to here as the Dokdo Abyssal Current. The width of the abyssal current is about 20 km below 1800 m depth. The low-frequency variability of the transports is dominated by fluctuations with a period of about 40 days for inflow and outflow transports. The 40-day fluctuations of both transports are statistically coherent, and occur almost concurrently. The overall mean transport of the deep water below 1800 m into the Ulleung Basin over the 16.5 months is about 0.005 Sv (1 Sv=106 m3 s?1), with an uncertainty of 0.025 Sv indicating net transport is negligible below 1800 m through the UIG.  相似文献   

8.
本文利用1993–2019年基于海表面高度异常的涡旋数据集和高度计数据统计分析了日本海区域中尺度涡旋的大小、极性、生命周期、振幅、传播等表面特征的时空变化规律。27年间,共探测到1 429个涡旋,气旋和反气旋数量基本相当,其中气旋675个,反气旋754个。两种极性涡旋均具有较强的季节变化:秋季较多,冬季次之,春季最少。郁陵盆地、大和盆地等为涡旋多发区域呈现西南–东北向带状分布。其中,南部海域反气旋占优,靠近津轻海峡的北部海域气旋占优。西部和南部受东韩暖流和对马暖流的驱动,涡旋移动方向与流场基本一致,北部涡旋与黎曼寒流以及副极地锋流有关。研究表明,动力学不稳定是涡旋在秋冬季大量产生的重要原因。此外,半封闭盆地、局地流场以及复杂的海气相互作用等都可能会对涡旋的产生和消亡造成一定影响。  相似文献   

9.
Seasonal Variation of the Cheju Warm Current in the Northern East China Sea   总被引：1，自引：1，他引：1  
The Cheju Warm Current has been defined as a mean current that rounds Cheju-do clockwise, transporting warm and saline water to the western coastal area of Cheju-do and into the Cheju Strait in the northern East China Sea (Lie et al., 1998). Seasonal variation of the Cheju Warm Current and its relevant hydrographic structures were examined by analyzing CTD data and trajectories of satellite-tracked drifters. Analysis of a combined data set of CTD and drifters confirms the year-round existence of the Cheju Warm Current west of Cheju-do and in the Cheju Strait, with current speeds of 5 to 40 cm/s. Saline waters transported by the Cheju Warm Current are classified Cheju Warm Current water for water of salinity greater than 34.0 psu and modified Cheju Warm Current for water having salinity of 33.5–34.0 psu. In winter, Cheju Warm Current water appears in a relatively large area west of Cheju-do, bounded by a strong thermohaline front formed in a "" shape. In summer and autumn, the Cheju Warm Current water appears only in the lower layer, retreating to the western coastal area of Cheju-do in summer and to the eastern coastal area sometimes in autumn. The Cheju Warm Current is found to flow in the western channel of the Korea/Tsushima Strait after passing through the Cheju Strait, contributing significantly to the Tsushima Warm Current.  相似文献   

10.
本文全面地分析了此段海流的流路与流速结构，首次提出研究海域近底层的环流示意图。指出在夏季，韩国南岸和日本九州北岸均存在着一支南下的逆流，九州西岸出现两种或多种形式的流路。对马暖流在源地流速很弱，流向不稳定，流路时隐时显不明显，只有离开源地后才逐渐显示出一支海流轮廓；强流区在朝鲜海峡附近。该海流可明显地划分为三段。流速夏强冬弱，夏季流幅宽约８０ｋｍ。  相似文献   

11.
To better understand the cause of high summer primary productivity in the Ulleung Basin located in the southwest part of the East/Japan Sea, the spatial dynamics of primary, new, and regenerated productivities (PP, NP, and RP) were examined along the path of the Tsushima Warm Current system in summer 2008. We compared hydrographic and chemical parameters in the Ulleung Basin with those of the Kuroshio Current in the Western Pacific Ocean and the East China Sea. In summer, integrated primary productivity (IPP, 0.37–0.96 g C m−2 d−1) and integrated new productivity (INP, 26–221 mg N m−2 d−1) within the euphotic zone in the Ulleung Basin were higher than those in the East China Sea and the Western Pacific Ocean (0.17–0.28 g C m−2 d−1, 2−5 mg N m−2 d−1, respectively). In contrast, there was no pronounced spatial variation in integrated regenerated productivity (IRP, 43–824 mg N m−2 d−1). Strong positive correlations between IPP and INP (also the f-ratio), and between nitrate uptake rate in the mixed layer and nitrate upward flux through the top of pycnocline in summer in the Ulleung Basin imply that the high IPP was mainly supported by supply of nitrate from the underlying water in the euphotic zone. Shallowing of the pycnocline depth as the current enters the East/Japan Sea facilitates nitrate supply from the nutrient-replete cold water immediately below the pycnocline through nitrate upward flux. A subsurface maximum in PP at or above the pycnocline and a high f-ratio further support the importance of this source of nitrate for maintaining the high summer PP in the Ulleung Basin. In comparison, the high PP layer was observed at the surface in the following fall and spring in the Ulleung Basin. Our results demonstrate the importance of hydrographic features in enhancing PP in this oligotrophic Tsushima Warm Current system.  相似文献   

12.
The seasonal variation in the barotropic mode of motion caused by joint effect of the baroclinicity and bottom relief (Jebar effect) in the Tsushima Strait is investigated with the use of the diagnostic numerical model in this study. The Jebar effect in the Tsushima Strait is mainly caused by the intrusion of the Bottom Cold Water along the Korean coast in summer. This Jebar effect along the Korean coast locally supplies the negative vorticity in situ, and it forces the coastal current to be intensified. In summer, the volume transport of the Tsushima Warm Current entering the Tsushima Strait is biassed to the western part of the strait comparing with the flow pattern calculated in winter.  相似文献   

13.
In order to reconstruct the circulation in the northern Greenland Sea, between 77°N and 81°N, and the exchanges with the Arctic Ocean through Fram Strait, a variational inverse model is applied to the density field observed in summer 1984 during the MIZEX 84 experiment. An estimate of the three-dimensional large-scale pressure field is obtained in which the solution is decomposed into a limited number of vertical modes and the mode amplitudes are described by piece-wise polynomials on a finite-element grid. The solution should be consistent with a frictional depth-integrated vorticity balance and with the density data. The global model parameters are tuned to ensure agreement between the retrieved geostrophic velocity and independent currentmeter data. In a companion paper (Schlichtholz and Houssais, 1999b), the same method, but without dynamical constraint, is applied to the same hydrographic dataset to perform a detailed water mass analysis and to estimate individual water mass transports.A comprehensive picture of the summer geostrophic circulation in Fram Strait is obtained in which northward recirculations in the East Greenland Current (EGC) and various recirculations from the West Spitsbergen Current (WSC) to the EGC are identified. It is suggested that the branch of the WSC following the upper western slope of the Yermak Plateau turns westward beyond 81°N and recirculates southward along the lower slope, then merging with a westward recirculating branch south of 79°N. At 79°N, a southward net transport of 6.5 Sv is found in the EGC which, combined with a northward net transport of only 1.5 Sv in the WSC, results in a fairly large outflow of 5 Sv from the Arctic Ocean to the Greenland Sea.The inverse solutions show that, in summer, the local induction of vorticity by the wind stress curl or by meridional advection of planetary vorticity should be small, so that, in the EGC and in the WSC, the vorticity balance is mainly achieved between the bottom pressure torque and dissipation of vorticity through bottom friction. A substantial barotropic flow associated with along-slope potential energy gradients is indeed identified on both sides of the strait.  相似文献   

14.
In the deepest region of Korea Strait, the surface temperature is highest in August (lowest in March), while the near-bottom temperature is lowest in September (highest in May). Cross-spectral analysis of the monthly temperature data between the two layers shows high coherence at the annual frequency with phase of 154°. Why and how does such a nearly opposite phasing occur between the surface and the near-bottom temperatures there? This study aims at answering these questions using historical and recently observed data.Cold and relatively fresh subsurface water flowing southward along the east coast of Korea and, known as the North Korean Cold Water (NKCW), becomes noticeable in April near the Sokcho coast. The zonal temperature gradient there is largest around June. The width of the NKCW becomes larger from April to August. After October, the NKCW retreats back toward the coast. The southward movement of the NKCW is thus strong over a period of six to seven months and weak in winter, especially in February. The NKCW flows southward relatively quickly along the coast in April to October and arrives at the Ulleung Basin within one to two months. Because of the sill between the Ulleung Basin and Korea Strait, this water cannot continue to flow to south, but piles up for about two to three months before it moves over the sill. The convergence of the subsurface cold water in the Ulleung Basin displaces the isopycnals upward and this water then intrudes over the sill along the isopycnals. This explains why in April or May, when this water appears noticeably at the Sokcho coast, the near-bottom water in Korea Strait is warmest and in August or September when the NKCW, which is piled up enough at the southern end of the Ulleung Basin, intrudes to Korea Strait, the near-bottom temperatures there are at their lowest.The origin of the NKCW seems to be the water of salinity less han 34.1 psu and surface density of 27σθ or higher, which sinks in the northwestern East Sea in January-March. The sinking of the water results from surface cooling in winter and is intensified due to the strong negative windstress curl. The cold and relatively fresh water, formed in the northwestern East Sea, is hypothesized to flow to the Ulleung Basin along three major paths, along the east coast of Korea, through the channel north of Ulleung-do Island, and through the channel between Ulleung-do and Dok-do Islands.  相似文献   

15.
The total organic carbon (TOC) and total inorganic carbon (CT) exchange between the Atlantic Ocean and the Mediterranean Sea was studied in the Strait of Gibraltar in September 1997. Samples were taken at eight stations from western and eastern entrances of the Strait and at the middle of the Strait (Tarifa Narrows). TOC was analyzed by a high-temperature catalytic oxidation method, and CT was calculated from alkalinity–pHT pairs and appropriate thermodynamic relationships. The results are used in a two-layer model of water mass exchange through the Strait, which includes the Atlantic inflow, the Mediterranean outflow and the interface layer in between. Our observations show a decrease of TOC and an increase of CT concentrations from the surface to the bottom: 71–132 μM C and 2068–2150 μmol kg−1 in the Surface Atlantic Water, 74–95 μM C and 2119–2148 μmol kg−1 in the North Atlantic Central Water, 63–116 μM C and 2123–2312 μmol kg−1 in the interface layer, and 61–78 μM C and 2307–2325 μmol kg−1 in the Mediterranean waters. However, within the Mediterranean outflow, we found that the concentrations of carbon were higher at the western side of the Strait (75–78 μM C, 2068–2318 μmol kg−1) than at the eastern side (61–69 μM C, 2082–2324 μmol kg−1). This difference is due to the mixing between the Atlantic inflow and the Mediterranean outflow on the west of the Strait, which results in a flux of organic carbon from the inflow to the outflow and an opposite flux of inorganic carbon. We estimate that the TOC input from the Atlantic Ocean to the Mediterranean Sea through the Strait of Gibraltar varies from (0.97±0.8)104 to (1.81±0.90)104 mol C s−1 (0.3×1012 to 0.56×1012 mol C yr−1), while outflow of inorganic carbon ranges from (12.5±0.4)104 to (15.6±0.4)104 mol C s−1 (3.99–4.90×1012 mol C yr−1). The high variability of carbon exchange within the Strait is due to the variability of vertical mixing between inflow and outflow along the Strait. The prevalence of organic carbon inflow and inorganic carbon outflow shows the Mediterranean Sea to be a basin of active remineralization of organic material.  相似文献   

16.
The effect of mesoscale eddy variability on the Japan/East Sea mean circulation is examined from satellite altimeter data and results from the Naval Research Laboratory Layered Ocean Model (NLOM). Sea surface height variations from the Geosat-Exact Repeat Mission and TOPEX/POSEIDON altimeter satellites imply geostrophic velocities. At the satellite crossover points, the total velocity and the Reynolds stress due to geostrophic mesoscale turbulence are calculated. After spatial interpolation the momentum flux and effect on geostrophic balance indicates that the eddy variability aids in the transport of the Polar Front and the separation of the East Korean Warm Current (EKWC). The NLOM results elucidate the impact of eddy variability on the EKWC separation from the Korean coast. Eddy variability is suppressed by either increasing the model viscosity or decreasing the model resolution. The simulations with decreased eddy variability indicate a northward overshoot of the EKWC. Only the model simulation with sufficient eddy variability depicts the EKWC separating from the Korean coast at the observed latitude. The NLOM simulations indicate mesoscale influence through upper ocean-topographic coupling. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

17.
By using a rectangular basin of uniform depth with inflow and outflow openings, the circulation in the Japan Sea is investigated numerically. Heat flux through the sea surface is determined from the annual mean atmospheric conditions for the Japan Sea, but no wind stress is considered.In the transient state, the warm water supplied through an inflow opening travels cyclonically along the coast as a density-driven boundary current in a rotating system. In the quasi-steady state, the warm water flows northward as a western boundary current which corresponds to the East Korean Warm Current and gradually separates from the coast as it flows northward. No strong boundary current corresponding to the nearshore branch of the Tsushima Current exists.Under annual mean atmospheric conditions, formation of the deep water characteristic of the Japan Sea and of the thermal front corresponding to the Polar Front do not take place.  相似文献   

18.
The Bransfield Strait west of the Antarctic Peninsula has been considered as a highly productive region for all trophic levels from primary production, to zooplankton aggregations, especially krill, to birds and mammals. The western boundary current, referred to as the Bransfield Current, plays an important role in determining the transport and retention of biota in the Bransfield Strait. Following the study of surface current characteristics in the strait using 39 tracks of mixed-layer drifters deployed between 1988 and 1990, a high-resolution transect of temperature, salinity and current measurements crossing the Bransfield Current was conducted between 13 and 14 March 2004, for understanding its horizontal and vertical structure and dynamics. The results from current, temperature and salinity measurements using a vessel mounted narrow band acoustic doppler current profiler and conductivity–temperature–depth (CTD) sensors revealed the magnitude of this current of approximately 50 cm/s within a horizontal distance of 15 km associated with a narrow and deep density front 4–6 km wide and 500 m deep. The comparison between the direct current measurements and the geostrophic current estimates from the density field implies that the Bransfield Current is geostrophically balanced. The mechanism forming this current is explored with Sverdrup dynamics. Results indicate that the negative wind stress curl and β-effect lead to a southwestward transport in the Bransfield Strait. When this transport is restricted by land and shelves, a narrow western boundary current is formed.  相似文献   

19.
The Ulleung Basin is one of three deep basins that are contained within the East/Japan Sea. Current meter moorings have been maintained in this basin beginning in 1996. The data from these moorings are used to investigate the mean circulation pattern, variability of deep flows, and volume transports of major water masses in the Ulleung Basin with supporting hydrographic data and help from a high-resolution numerical model. The bottom water within the Ulleung Basin, which must enter through a constricted passage from the north, is found to circulate cyclonically—a pattern that seems prevalent throughout the East Sea. A strong current of about 6 cms−1 on average flows southward over the continental slope off the Korean coast underlying the northward East Korean Warm Current as part of the mean abyssal cyclonic circulation. Volume transports of the northward East Korean Warm Current, and southward flowing East Sea Intermediate Water and East Sea Proper Water are estimated to be 1.4 Sv (1 Sv=10−6 m3 s−1), 0.8 Sv, and 3.0–4.0 Sv, respectively. Deep flow variability involves a wide range of time scales with no apparent seasonal variations, whereas the deep currents in the northern East Sea are known to be strongly seasonal.  相似文献   

20.
Long-term, continuous, and real-time ocean monitoring has been undertaken in order to evaluate various oceanographic phenomena and processes in the East/Japan Sea. Recent technical advances combined with our concerted efforts have allowed us to establish a real-time monitoring system and to accumulate considerable knowledge on what has been taking place in water properties, current systems, and circulation in the East Sea. We have obtained information on volume transport across the Korea Strait through cable voltage measurements and continuous temperature and salinity profile data from ARGO floats placed throughout entire East Sea since 1997. These ARGO float data have been utilized to estimate deep current, inertial kinetic energy, and changes in water mass, especially in the northern East Sea. We have also developed the East Sea Real-time Ocean Buoy (ESROB) in coastal regions and made continual improvements till it has evolved into the most up-to-date and effective monitoring system as a result of remarkable technical progress in data communication systems. Atmospheric and oceanic measurements by ESROB have contributed to the recognition of coastal wind variability, current fluctuations, and internal waves near and off the eastern coast of Korea. Long-term current meter moorings have been in operation since 1996 between Ulleungdo and Dokdo to monitor the interbasin deep water exchanges between the Japanese and Ulleung Basins. In addition, remotely sensed satellite data could facilitate the investigation of atmospheric and oceanic surface conditions such as sea surface temperature (SST), sea surface height, near-surface winds, oceanic color, surface roughness, and so on. These satellite data revealed surface frontal structures with a fairly good spatial resolution, seasonal cycle of SST, atmospheric wind forcing, geostrophic current anomalies, and biogeochemical processes associated with physical forcing and processes. Since the East Sea has been recognized as a natural laboratory for global oceanic changes and a clue to abrupt climate change, we aim at constructing a 4-D continuous real-time monitoring system, over a decade at least, using the most advanced techniques to understand a variety of oceanic processes in the East Sea.  相似文献   

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