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1.
We conducted hydrographic observations ten times in the Tsushima Strait to reveal seasonal variations of horizontal material transports such as of heat, freshwater, chlorophyll a, and dissolved inorganic nitrogen (DIN) and phosphorus (DIP) through the eastern channel of the Tsushima Strait (ECTS). The volume, freshwater, and heat transport results are of nearly the same order as results reported in previous studies. The annual mean DIN and DIP transports of 3.59 kmol/s and 0.29 kmol/s are large relative to those of the Changjiang and the Taiwan Strait and are horizontally transported through the ECTS. Nutrient transports are high in July–August and October and low in April and November. Increased nutrient transports in July–August and October are due to the appearance of a cold saline water mass in the bottom layer of the ECTS. Changes in DIN transports in summer and autumn, which account for two-thirds of the total annual DIN transport, would have a large effect on the nitrogen budget and biological productivity in the Tsushima Warm Current region.  相似文献   

2.
The relations between the volume transport and the sea level difference across the Tsushima Straits have been investigated using current data provided by ADCP mounted on the ferry Camellia, plying between Hakata and Pusan. Empirical formulas to deduce the volume transports using the sea level differences across the eastern and western channels are proposed, considering the seasonal variation of the vertical current structure. The interannual variation of volume transport through the Tsushima Straits for 37 years from 1965 to 2001 is estimated using the empirical formulas. The total volume transport through the Tsushima Straits, averaged for 37 years, is 2.60 Sv and those of the eastern and western channels are 1.13 Sv and 1.47 Sv, respectively. The total volume transport through the Tsushima Straits tends to decrease with a roughly 15 year variation until 1992, then begins to increase.  相似文献   

3.
The Current Structure of the Tsushima Warm Current along the Japanese Coast   总被引：4，自引：0，他引：4  
The branching of the Tsushima Warm Current (TWC) along the Japanese coast is studied based upon intensive ADCP and CTD measurements conducted off the Wakasa Bay in every early summer of 1995–1998, the analysis of the temperature distribution at 100 m depth and the tracks of the surface drifters (Ishii and Michida, 1996; Lee et al., 1997). The first branch of TWC (FBTWC) exists throughout the year. It starts from the eastern channel of the Tsushima Straits, flows along the isobath shallower than 200 m along the Japanese coast and flows out through the Tsugaru Strait. The current flowing through the western channel of the Tsushima Straits feeds the second branch of TWC (SBTWC) which develops from spring to fall. The development of SBTWC propagates from the Tsushima Straits to Noto Peninsula at a speed of about 7 cm sec−1 following the continental shelf break with a strong baroclinicity. However, SBTWC cannot be always found around the shelf break because its path is influenced by the development of eddies. It is concluded that SBTWC is a topographically steered current; a current steered by the continental shelf break. Salient features at intermediate depth are the southwestward subsurface counter current (SWSCC) between 150 m and 300 m depths over the shelf region in 1995–1998 with the velocity exceeding about 5 cm sec−1, although discrepancies of the velocity and its location are observed between the ADCP data and the geostrophic currents. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

4.
ＯｎｔｈｅｏｒｉｇｉｎｏｆｔｈｅＴｓｕｓｈｉｍａＷａｒｍＣｕｒｒｅｎｔＷａｔｅｒ￥ＴａｎｇＹｕｘｉａｎｇａｎｄＨｅｕｎｇ－ＪａｅＬｉｅ（ＦｉｒｓｔｉｎｓｔｉｔｕｔｅＯｆＯｃｅａｎｏｇｒａｐｈｙ，ＳｔａｔｅＯｃｅａｎｉｃＡｄｍｉｎｉｓｔｒａｔｉｏｎ，Ｑ...  相似文献   

5.
本文通过二维数值模拟对1986年6月～1988年12月东海对马暖流水的来源问题进行了初步探讨,结果得出东海对马暖流水的来源基本上分为三种类型:(1)东海对马暖流水主要为东海黑潮水继续北上部分构成;(2)东海对马暖流水由东海黑潮水、东海陆架水以及东海北部黄海大陆沿岸水几部分混合而成;(3)东海对马暖流水几乎全部由东海北部的黄海大陆沿岸水构成。模拟与实测结果基本一致.  相似文献   

6.
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   

7.
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   

8.
We discussed the detailed current structures in the Eastern Channel of the Tsushima Strait, using four sets of acoustic Doppler current profiler (ADCP) data, which were taken by the quadrireciprocal method (Katoh, 1988), for removing tidal currents, in summers of 1987–1989. In the Eastern Channel, diurnally averaged currents balanced almost geostrophically. In the upper layer of the deepest part of the Eastern Channel, there existed a current core which corresponded to one branch of the Tsushima Current. The current direction in this core was between NE and ENE in all observations but the magnitude of velocity in 1987 differed largely from that in 1988. Another current core with lower velocities was found near the north coast of Kyushu. Near the bottom at the deepest part of the Eastern Channel, the velocity was more or less 0.3 kt (15 cm s–1). Along the east coast of Tsushima and in waters northeast of it, countercurrents were observed. The continuity of these countercurrents was interpreted as follows: A part of the current flowing from the Western Channel of the Tsushima Strait into the Japan Sea turns clockwise in waters northeast of Tsushima, and flows southwestward along the east coast of Tsushima. The southwestward current along Tsushima was correlated with the northeastward current in the central part of the Eastern Channel. The transport through the Eastern Channel was between 0.59 and 1.30 Sv (1 Sv=106 m3s–1). The baroclinic component, which was defined as the transport based on calculations of geostrophic current with assuming zero velocity near the bottom, was very small.  相似文献   

9.
Northern and southern latitudinal transects were conducted west of Tsugaru Strait to estimate the volume transport in this area. It was found that the Tsushima Warm Current is the northward volume transport across the southern transect and the Northward Current is the northward volume transport across the northern transect. The current in Tsugaru Strait,viz. the Tsugaru Warm Current, is the flow remaining when the Northward Current is subtracted from the Tsushima Warm Current. Both CTD transects covered from near-shore to west of the subarctic front, and observed depths were from the surface to the bottom or to 1000-1500 m depth. Our estimations indicate that large interannual variations of volume transport occur, relative to the seasonal ones, with interannual variations sometimes exceeding seasonal variations in the Tsushima Warm Current and the Northward Current. The Tsugaru Warm Current has near-steady transport. Fluctuations in the Tsushima Warm Current are thus transmitted to the Northward Current. Further, our results revealed seasonal variations in the flow: the baloclinic structure became deeper in April and the current axis tended to shift in a near-shore direction in October. Therefore, previous studies, which had shallow reference levels and lacked nearshore stations, may have underestimated the transport and excessive seasonal variations.  相似文献   

10.
Sea surface temperature (SST) and sea surface salinity variations at Fukue Island (located southwest of the Tsushima Straits) were investigated. In spring, low-frequency SST fluctuations with periods of 10–20 days predominate. Synthetic analysis of in situ observation and satellite infrared image reveals that these SST fluctuations are caused by movement of mixed warm water masses which have a temperature intermediate between those of the Kuroshio and the East China Sea (ECS) shelf waters. Since these fluctuations do not correspond with those in the Tsushima Straits, it is indicated that these water masses can hardly pass the Tsushima Straits while retaining their original water properties. In July, SST fluctuations with a period of several days are also found at Fukue Island. Since these SST fluctuations show an opposite correspondence with its salinity fluctuations and a good correspondence with the SST fluctuations at Okinoshima in the Tsushima Straits, it is inferred that warm and low-salinity water originated from the ECS shelf water causes these fluctuations and intrudes into the Tsushima Straits.  相似文献   

11.
A significant surface net heat loss appears around the Kuroshio and the Tsushima Warm Current regions. The area where the surface heat loss occurs should require heat to be supplied by the current to maintain the long-term annual heat balance. Oceanic heat advection in these regions plays an important role in the heat budget. The spatial distribution of the heat supply by the Tsushima Warm Current near the surface was examined by calculating the horizontal heat supply in the surface layer of the East Sea (the Japan Sea) (ESJS), directly from historical sea surface temperature and current data. We have also found a simple estimation of the effective vertical scale of heat supply by the current to compensate net heat loss using the heat supplied by the current in the surface 10 m layer. The heat supplied by the current for the annual heat balance was large in the Korea/Tsushima Strait and along the Japanese Coast, and was small in the northwestern part of the ESJS. The amount of heat supplied by the current was large in the northwestern part and small in the south-eastern part of the ESJS. These features suggest that the heat supplied by the Tsushima Warm Current is restricted to near the surface around the northeastern part and extends to a deeper layer around the southeastern part of the ESJS. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

12.
A simple analytical model is considered for the dynamics of volume transport of the Tsushima Current. This model is basically baroclinic but allows bottom friction over the shallow regions connecting the Pacific Ocean to the Japan Sea basin, and is thus different from previous models which are either purely barotropic with bottom friction predominating over the whole domain, or purely baroclinic with bottom friction completely ignored. Compared to the previous barotropic model, this model is not only more realistic but also gives much simpler results. It gives the observed downstream sea level slope, which is not seen in the previous baroclinic model. As a result, the estimated transport of the Tsushima Current is closer to the observational data than those of previous models. This model indicates that the localized bottom friction acting over the shallow regions not only controls the transport of the Tsushima Current but also moves the stagnation point of the western boundary current northward. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

13.
Variability of Sea Surface Circulation in the Japan Sea   总被引：3，自引：0，他引：3  
Composite sea surface dynamic heights (CSSDH) are calculated from both sea surface dynamic heights that are derived from altimetric data of ERS-2 and mean sea surface that is calculated by a numerical model. The CSSDH are consistent with sea surface temperature obtained by satellite and observed water temperature. Assuming the geostrophic balance, sea surface current velocities are calculated. It is found that temporal and spatial variations of sea surface circulation are considerably strong. In order to examine the characteristics of temporal and spatial variation of current pattern, EOF analysis is carried out with use of the CSSDH for 3.5 years. The spatial and temporal variations of mode 1 indicate the strength or weakness of sea surface circulation over the entire Japan Sea associated with seasonal variation of volume transport through the Tsushima Strait. The spatial and temporal variations of mode 2 mostly indicate the temporal variation of the second branch of the Tsushima Warm Current and the East Korean Warm Current. It is suggested that this variation is possibly associated with the seasonal variation of volume transport through the west channel of the Tsushima Strait. Variations of mode 3 indicate the interannual variability in the Yamato Basin.  相似文献   

14.
Recent investigation suggests that volume transport through the Tsushima/Korea Strait often has double peaks during the summer to autumn period with decreasing transport in September. The satellite-observed wind changes from weak northwestward (across-strait) in summer to strong southwestward (along-strait) in early autumn (September) in the strait. Such a strong along-strait wind is related to tropical cyclones, which frequently pass through the East China Sea in September. The effect of the along-strait wind component on the transport variation is examined using a three-dimensional numerical model. The simulated volume transport through the Tsushima/Korea Strait shows realistic seasonal and intra-seasonal variations. According to sensitivity experiments on local winds, the transport variations in September are mainly generated by strong along-strait (southwestward) wind rather than weak across-strait wind. The strait transport responds to the along-strait wind (southeastward), which produces a sea level increase along the Korean coast, resulting in the geostrophic balance across the strait. The transport minimum through the Tsushima/Korea Strait in September can be determined by the combination of the across-strait geostrophic and along-strait ageostrophic balances. The Editor-in-Chief does not recommend the usage of the term “Japan/East Sea” in place of “Sea of Japan”.  相似文献   

15.
Downstream transition of the Tsushima Current west of Kyushu in summer   总被引：1，自引：0，他引：1  
In order to clarify detailed current structures west of Kyushu, ADCP measurements were carried out in July and September 1990 by the quadrireciprocal method (Katoh, 1988) for removing diurnal and semidiurnal tidal flows from observed flows. On the basis of these results, together with data of routine oceanographic observations, we study the downstream transition of the Tsushima Current west of Kyushu in summer. In the southwest of the Goto Islands, a northward current identified as the Tsushima Current was clearly found. In the south of Cheju, a westward current bifurcated from the Tsushima Current. In the northwest of the Goto Islands, the Tsushima Current narrowed and its velocity became strengthened. Salinity of the Tsushima Current water was much diluted by a current from the Cheju Strait. Near the west coast of the Goto Islands, a countercurrent bifurcating from the Tsushima Current often occurred. The volume transport of the Tsushima Current was 2.3 Sv (1 Sv=106 m3s–1) on the northern side of latitude 31°N. The substantial bifurcation of the Tsushima Current toward the Eastern and Western Channels of the Tsushima Strait occurred in the vicinity of Tsushima. The volume transport through the Western Channel was two to three times larger than that through the Eastern Channel. The baroclinic component in volume transport of the Tsushima Current west of Kyushu was much smaller than that in the Japan Sea.  相似文献   

16.
Wind-velocity data obtained from in situ measurements at the Golitsyno-4 marine stationary platform have been compared with QuikSCAT scatterometer data; NCEP, MERRA, and ERA-Interim global reanalyses and MM5 regional atmospheric reanalysis. In order to adjust wind velocity measured at a height of 37 m above the sea surface to a standard height of 10 m with stratification taken into account, the Monin–Obukhov theory and regional atmospheric reanalysis data are used. Data obtained with the QuikSCAT scatterometer most adequately describe the real variability of wind over the Black Sea. Errors in reanalysis data are not high either: the regression coefficient varies from 0.98 to 1.06, the rms deviation of the velocity amplitude varies from 1.90 to 2.24 m/s, and the rms deviation of the direction angle varies from 26° to 36°. Errors in determining the velocity and direction of wind depend on its amplitude: under weak winds (<3 m/s), the velocity of wind is overestimated and errors significantly increase in determining its direction; under strong winds (>12 m/s), its velocity is underestimated. The influence of these errors on both spatial and temporal estimates of the characteristics of wind over the Black Sea is briefly considered.  相似文献   

17.
Tidal currents in the Tsushima Straits have been analyzed using measurements obtained since February 1997 by an acoustic Doppler current profiler (ADCP) mounted on the ferryboat Camellia. Tidal current constituents (M 2, S 2, K 1, O 1) are dominant among the ten tidal current constituents (Q 1, O 1, P 1, K 1, N 2, M 2, S 2, K 2, MSf, Mf), and generally 1.4–2.1 times stronger at the western channel of the straits than those at the eastern channel. The ratio between amplitude of M 2, S 2, K 1 and O 1 averaged along the ferryboat track is 1:0.45:0.59:0.51. The major axis directions of tidal current ellipses are generally SW to NE, exceptionally in the vicinity of the Tsushima Islands. Approaching the Tsushima Islands from the Korean Peninsula side, the major axis gradually rotates clockwise. At the western channel, the M 2 and K 1 constituents change the rotation direction of current vectors from clockwise to counterclockwise at about 90–130 m depth. The contributions of the tidal currents to the mean kinetic energy and the mean eddy kinetic energy along the ferryboat track are, on average, 0.56 and 0.71, respectively. This suggests that tidal current activities are generally more dominant than the mean current activities and much more dominant than eddy activities. The only region where the eddy activities are comparable to the tidal current activities is located on the east side of the Tsushima Islands. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

18.
The most plausible scenarios for seasonal to interannual variabilities and their possible causes are investigated for the Tsushima Current system passing through the Japan Sea. The study is based on the north and south two-box model across the polar front in an idealized upper ocean of the Japan Sea. The boxes are connected by lateral diffusive heat transport and cooled by atmospheric forcing at the annual mean state. The south box, i.e. the Tsushima Current region, only interacts with the outside warmer box in the East China Sea and has an eastward thermal-driven current originating in the outside box. The magnitude of this current depends on the strength of the thermal gradient between the north and south boxes; the inflow of warm waters can therefore be maintained by net heat loss through the sea-surface. I call such a thermal-driven inflow process a "Cooling-Induced Current" system in the present study. Under periodical heat forcing, the perturbation response of the model to water temperature fields and inflow transport were examined. It is shown that the lateral diffusion time across the polar front (over a period of 10 years) is crucial to the interannual modeled response. An analysis of the seasonal heat budget suggests that the heat transported into the Japan Sea from the East China Sea in summer is stored mainly within the Tsushima Current region and contributes to heat loss by the sea-surface cooling in winter.  相似文献   

19.
By using Acoustic Doppler Current Profiler (ADCP) measurements with the four round-trips method to remove diurnal/semidiurnal tidal currents, the detailed current structure and volume transport of the Tsushima Warm Current (TWC) along the northwestern Japanese coast in the northeastern Japan Sea were examined in the period September–October 2000. The volume transport of the First Branch of the TWC (FBTWC) east of the Noto Peninsula was estimated as approximately 1.0 Sv (106 m3/s), and the FBTWC continued to flow along the Honshu Island to the south of the Oga Peninsula. To the north of the Oga Peninsula, the Second Branch of Tsushima Warm Current and the eastward current established by the subarctic front were recombined with the FBTWC and the total volume transport increased to 1.9 Sv. The water properties at each ADCP line strongly suggested that most of the upper portion of the TWC with high temperature and low salinity flowed out to the North Pacific as the Tsugaru Warm Current. In the north of the Tsugaru Strait, the volume transport of the northward current was observed to be as almost 1 Sv. However, the component of the TWC water was small (approximately 0.3 Sv).  相似文献   

20.
Marine surface winds observed by two microwave sensors, SeaWinds and Advanced Microwave Scanning Radiometer (AMSR), on the Advanced Earth Observing Satellite-II (ADEOS-II) are evaluated by comparison with off-shore moored buoy observations. The wind speed and direction observed by SeaWinds are in good agreement with buoy data with root-mean-squared (rms) differences of approximately 1 m s−1 and 20°, respectively. No systematic biases depending on wind speed or cross-track wind vector cell location are discernible. The effects of oceanographic and atmospheric environments on the scatterometry are negligible. Though the wind speed observed by AMSR also showed agreement with buoy observations with rms difference of 1.27 m s−1, the AMSR wind speed is systematically lower than the buoy data for wind speeds lower than 5 m s−1. The AMSR wind seems to have a discontinuous trend relative to the buoy data at wind speeds of 5–6 m s−1. Similar results have been obtained in an intercomparison of wind speeds globally observed by SeaWinds and AMSR on the same orbits. A global wind speed histogram of the AMSR wind shows skewed features in comparison with those of SeaWinds and European Centre for Medium-range Weather Forecasts (ECMWF) analyses.  相似文献   

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