Analysis of Yellow Sea circulation

Chinese Science Bulletin2003 Vol. 48 Supp. 12- -20long time. However, the previous basic knowledge of theYS circulation was presented mainly based on indirectAnalysis of Yellow Seainferences drawn mostly from the observations of tem-circulationperature (T) and salinity (S). Meanwhile, the most previ-ous oceanographic surveys of the YS were limited to theregion west of 124°E. Thus, KCC in the eastern YS hasZANG Jiayie1,2, TANG Yuxiang1:2, Z0U Emei1.2been understood poorly. Since the 1980s, the investigated& LIE Heung-Jae3area has extended to the nearshore area of the Korea1. Key Laboratory of Marine Science and Numerical Modeling, StatePeninsula along with the implementation of several mas-Oceanic Administration, Qingdao 266061, China;sive international cooperative investigations such2. First Institute of Oceanography, State Oceanic Administration, Qing-China- U.S.A.-Korea joint investigation of the YS (1986dao 266061, China;3. Korea Ocean Research & Development Institute, Seoul 425600, Ko--1987) and China-Korea Joint Investigation of OceanCirculation Dynamics in the southern YS (1996 - - 1998). .Correspondence should be addressed to Zang Jiaye (e mail:At the same time, investigation technique and equipmentysea@ public. qd.sd.cn)have been improved obviously. Especially, utilization ofAbstract Some features of the circulation in the Yellowthe advanced current meters such as satellite-trackedSea (hereafter referred to as YS) in the cold season (mid-drifters and Acoustic Doppler Current Profiler (ADCP)November through mid-April) are analyzed emphatically bynot only measures quite integrally the paths of some mainusing the observations of several large-scale surveys in e-cent years together with historical data. Compared with thecurrent systems, but also can get long-term current data inprevious studies, a wealth of observed data have firstly beendifferent layers. Thus, the directly measured current dataused in this study to further discuss the origin and path ofincrease obviously, and therefore the understanding of thethe Yellow Sea Warm Current (YSWC). The analyses showYS circulation has been deepened greatly. Of them, thethat the YSWC is not a direct branch of the Tsushima Warmrelatively outstanding is that some new views on the ori-Current (TSWC), but derives from the mixed water regiongin, path and their seasonal variations of the YSWC are :formed by TSWC water and the continental shelf water ofthe East China Sea (ECS). The path of the YSWC has cer-proposed6 -1"; a quite stable current around Cheju Island,tain seasonal and interannual variations. Then, the basici.e., CWC is discoveredl9); and KCC in the eastern YS isfeatures of the Cheju W arm Current (CWC) discovered infurtherl9.10) understood.recent years and its relation to the YSWC are expounded.In this study, some of the above-mentioned newThe studies indicate that the CWC and the YSWC comeviews on the YS circulation will be further studied basedbasically from the same origin, and the main path of CWC islocated roughly in water depths of greater than 80 m north-on the various observed data collected up to now and thewest of_ Chejudo. At last, the distribution features of theprevious analyses1-131 in order to have a better under-Korea Coastal Current (KCC) are delineated according tostanding of this circulation.the new observations. The results show that the KCC movesPrevious investigations and studies show that thetoward south along the 40 - 50 m isobaths west of the Kore-hydrographical conditions and circulation structures in thean Peninsula, and its velocity increases from north to south.YS can be classified roughly into two types: cold seasonKeywords: Yellow Sea, circulation, cold season.pattern (mid Nov. through mid Apr.) and warm seasonpattern (mid Apr. through mid Nov) centred on winter andDOI: 10.1360/01we0103summer, respectively. The outstanding features of hy-The study on oceanic circulation is the most basicdrographical phenomena are that a warm and saline watertongue extends from the area west of Cheju Island to thetask of marine science and, moreover, the core of physicalnorthern YS in the cold season and the cold water massoceanography all along. The oceanic circulation is alsooccupies the wide bottom waters of YS in the warm sea-the background and carrier of the occurrence of variousson. Corresponding to the hydrographical features, thoceanic processes. The distributions of mass, momentumcirculation structures in the cold season and warm seasonand energy in the ocean depend, in the final analysis, onare obviously different. Therefore the circulation in thethe long-term continued transporting process of the oce-cold season will be discussed emphatically in this study,anic circulation. Up to now, a lot of the investigations andand the circulation in the warm seasons will be analyzedstudies of the YS circulation have been carried out. Notin another study.only the basic structures of the HS circulation have been1 YSWC and its extensionsketched, but also some valuable conclusions have beenproposedI' -11 Of them, some basic views proposed byYSWC is the main component of the YS circulationUall.2I, NitaniB)1 and Guanl41) have dominated the under- and中国煤化工external water with highstanding of people in the oceanic circulation for quite aTHHCNMHG1) Guan Bingxian, Chen Shangji, Current system in the Chinese seas, in an unpuonsned( omprenensive Keport of National Marine Investigation(in Chinese), Vol. 5, 1964.12Chinese Science Bulletin Vol. 48 Supp. June 2003and high S into the YS. Obviously, the YSWC plays ancm/s. Station M is just located in the fore part of theimportant role in the YS. Previous studies on the YSWCwarm and saline tongue. Thus, the observed results showconcentrate mainly on its origin, path and their seasonalthat the Y SwC in the warm and saline tongue area of thevariations.central YS did not flow northward along the trough, but(_ i) Character and path of the YSWC. As early asflowed at the western flank of the trough and in a direc-the beginning of the 1930s, Uda (1934, 1936) proposedtion parallel to the warm and saline tongue axis.for the first time a comprehensive schematic pattern of theYS circulation. According to his circulation pattern, the38° NYSWC is branched from the TSWC southwest of Chejudo,and moves northward along the YS trough, which is also6.0supported by NitaniB), Guan!4] and Chenl5I. According to36°7.0 7.0the observations of six measured current moorings in theYS trough during January-April of 1986, Hsuehl0 sug-g0gested that the variation of the Y SWC was quite obviousand closely related to the meso-scale marine processes.34°Accordingly, it is thought that the Y SWC is a compensati-Chinaon current, which is largely the same as the jet flow pro-posed by Guanl4] based on the observations. This impliesthat the YSWC in the YS moves along the axis of the329.0(awarm and saline water tongue rather than its margin.However, a lot of satellite images and the hydrographicalobservations show that the axis of the warm and salinewater trough is mostly to the west side of the YS trough.On these grounds, it is considered by Yuan!4] and Guol15]that the YSWC moves northward along the 50- -60 m36isobaths west of the trough rather than the YS trough.The running of the warm and saline tongue ex-tending into the YS is often taken as a qualitative index ofthe moving direction of the Y SWCI5.161). Following thismethod, the distribution of the YSWC path has been ana-lyzed in great detail based on the observed data of T andSI2131. Results show that the Y SWC path has certain sea-sonal and inter-annual variations. The path is to the west32。side of the YS trough in most of years, but goes northward(b) Ialong the trough in a few years. Meanwhile, the analyses120°122*124。126indicate that the variations of the YSWC path, as a com-pensation flow, are closely related to the strength of mon-soon. The above views can be further confirmed by thefollowing evidence.Station M (surface)Evidence. I. The first cruise of“China- Korea JointInvestigation of Ocean Circulation Dynamics in the YS”was carried out in April 1996. The horizontal distributionsof T and S in the surface layer during this cruise are ilus-Station M (20 m depth)trated in Fig. 1. It is shown from Fig. 1 that the axis of thewarm and saline tongue extends northwestward and doesnot go northward along the YS trough. During this cruise,the consecutive current observation lasting for 3 days wasM、Station M (50 m depth)conducted at 34°N, 123930 'E (station M) in the warmand saline tongue area of the central Y S. The results (Fig.1(C)) show that the directions of the residual current were中国煤化工basically northwest in both surface and bottom layers andc) Inortheast at the 20 m depth with a speed of 3 - -5YHCNMHGFig.1. Horizontal distributions of T (a) and S (b) in surface layer and1) See the footnote on page 12.residual curent vectors at mooring station M, (C) in Apr. 1996.Chinese S府亦数letin Vol. 48 Supp. June 20033Evidence 2. Several satellite tracked drifters wereand dropped greatly from about 20.( to 6.( in the shal-deployed in the warm and saline tongue area in Aprillow-water area. These distributional features of T imply1996 and February 1997, respectively, during China-that there exists the heat advection along the axis of theKorea joint investigation on the YS. The trajectories ofwarm and saline tongue, which is an important evidencethe drifters are illustrated in Fig. 2. Of them, the initialfor the existence of the Y SWC and indicates that the pathposition of a drifter deployed in the central YS in Aprilof the YSWC was to the west side of the YS trough.1996 was close to station M shown in Fig. 1(c). Thisdrifter moved quite slowly toward the west at beginning,then turned gradually toward the north after 12 days and 37 °NEmoved by north at a speed of 4.5 cm/s. The drifter deploy-Chinaed at 35°N, 122°E in Feb. 1997 moved toward the north-west at a speed of about 2.4 cm/s in quite a long period_8.0and then turned toward southwest. It is shown from the35distributions of T and S in the same period that the mov-ing pathways of the two drifters located in the warm andsaline tongue area show roughly the trend of the warmand saline water flowing in the axis direction at the west-31ern flank of the YS trough.38 N不a)37°36°小41997.234°八十1996.433。6.0(b)t 199723I119°121123°127° E32。Fig. 3. Distribution of T in bottorm layer in the autumn of 1996 and thewinter of 1997.122°124°126° FAlthough evidence 2 and 3 show only the currentpatterns in the surface and bottom layers, respectively, itFig. 2. Trajectories of salite-tracked drifters.can be known by combining them with previous investi-Evidence 3. The distributions of T in the bottom gations and studiesl45.1) that the YsWC, after enteringlayer in the autumn of 1996 and the winter of 1997 arethe YS, moves basically toward the north by northwest inillustrated in Fig. 3. It is shown from Fig. 3 that the waterthe cold season except that the surface current direction istemperature in the region surrounded by the 102 ( iso-likely to the south under the effects of the strong norththerm in winter is obviously higher (about 1 .51 0 than thatwind. To go further into the moving path of the YSWCin the same region in autumn. However, the temperaturewate中国煤化工ral axis of the warm andon both sides of the warm tongue in winter is lower thansalin2ars and different seasonsthat in autumn. Especially, the water temperature in the areYHC N M H Gles indicate the northernarea west of the warm and saline tongue in winter de-limit of the isohaline 33.0 and solid circles show thecreased by more than 51 ( compared with that in autumnnorthwestern limits of the isohaline 34.0. It is shown from1) See the footnote on page 12.14Chinese Science Bulletin Vol. 48 Supp. June 2003Fig. 4 that the axes of the warm and saline tongue werewater and the ECS continental shelf waterl9. However, itlocated in the YS trough only in Jan. of 1986 and obvi-should be pointed out that these views have been proposedously at the western flank of the YS trough in other years.mainly based on the observations of T and S. In recentAs to the seasonal distributions, the northward extendingyears, Korea scientists have proposedl201 that the YSWC isrange of the isohaline 33.0 in Feb. was obviously larger not a persistent mean current, but is only an intermittentlythan that in Jan. and the position of the axis in May was togenerated wind-driven current. Meanwhile, it is consid-the furthest west.ered that the YSWC water is formed by mixing of theCWC water and the ECS continental shelf water20.21. Up38。to now, the origin of the YSWC is still in controversy.However, it can be found through careful analyses that thecontroversial opinions can be classified basically into twoChinakinds. The first is that the YSWC separates from theTSWC; the second claims that the YSWC is a branch of anortheast continuation of TWC. After analyzing the long-erm hydrographical observations and directly observed36current data, Tang et al. reported that the YSWC originat-ed directly neither from the TSWC nor from the TWC,and derived from the frontal area formed by the TSWCwater and the shelf water, which can be verified further by01959.1other evidence collected in recent years.To keep step with World Oceanic Circulation Ex-periments (WOCE)， 172 satellite-traced drifters were34°-19972deployed by KORDI in the northwestern Pacific Ocean,the continental margin and the northeastern ECSI221. Fig. 1of Ref. [22] ilustrates the moving trajectories of these， 1999drifters and the surface current field derived from the1998.50 1986. Itrajectories. This figure shows quite clearly that TSWC isseparated from the Kuroshio near 30°N, 128E and flowsnorthward along the continental margin between the 10032%m and 200 m isobaths. However, of so many drifters, no122124 。126'Eone enters into the area west of Chejudo, which indicatesFig. 4. Position of the main axis of the warm and saline tongue inthat the TSWC does not separate directly a branch to enterdifferent seasons and years.the YS in the area southeast of Chejudo.As regards the path of the YSWC after reachingAs regards the opinion that the YSWC originates35°N, it can be inferred further by referring to the numeri-from the TWC, Lie et al. have denied this opinion on thecal results. It is shown from the calculationsl7] that thebasis of the hydrographical analyses. During the comple-YSWC does not enter directly into the norther YS after mentary investigations on the YS and ECS, 4 Clear-Sat-15going up to the north, its main stream turns to the northsatellite tracked drifters were deployed during January 27-firstly at about 35°10-'N， 12630-'E and separates a28, 1999 with a purpose of monitoring the origin and thebranch to merge with the YS coastal current and flowspath of the TWC in winter. It is shown from the trajectori-southward; then after entering the northern YS, the maines of the four drifters and the sea surface temperaturestream separates another east branch at about 37°N toalong the moving path in Fig. 5 that the TWC water inmerge with the southward flowing KCC, and its mainwinter originates mainly from the surface Kuroshio water.stream finally flows westward to enter the Bohai Sea.The TWC begins to separate at about 27 °N. One branchThese calculated results are basically consistent with thoseturns to the east roughly along the 90 m isobath andpresented by Su[18] according to the observations of Tmerges into the Kuroshio; the rest moves northeastwardand S.approximately along the 60 m isobath. Although the sig-(- i) Origin of YSWC. As a current coming fromnals of the drifter broke off for a variety of reasons, it canthe open sea with high T and S, YSWC is closely relatedbe inferred from the hydrological analyses that the north-to the Kuroshio coming from the Pacific Ocean and itsward flowing TWC also finally merges into the Kuroshiobranch TSWC. Many scholars have suggested1 “75.4“16]in th中国煤化工in ref. [22] shows that thethat the YSWC is branched from the TSWC in the seadriftfYHc N M H Chio rgion yually do notarea southwest of Chejudo. However, some scholars havesepallse measured current datathought that the YSWC comes mainly from the TWC17.17.imply that up to now there have been no indications thatMeanwhile, some scholars have believed that the YSWCthe TWC can detach a branch to directly enter the YS. Aswater in winter is formed by lateral mixing of the TWCto hydrographical properties, the charac-Chinese St亦数据/etin Vol. 48 Supp. June 2003529^N50 cm/s31a3/0528。773/01China3/23k2/20 3/15 3/20 I3/2527"2/062/15 3/103/31143/01272/256°11940128 13362/2091271/30 2102/01 2/05(a)25°29°N, 78.017.717.8 18.0 18.8 18.5x 20.621.1 005 1518.78.112.412.9 16.607.026°18.8 1817.8.07.8. 20.1(b120°] 22°124°126° EFig. 5. Trajectories (a) of slte-tracked drifters and sea surface temperature (b) along the moving path of the drifters in winter 1999.teristics of T and S of the YSWC water are quite differentof tracing the movement of sea water. It is worth pointingfrom those of the TSWC water and the TWC water, alt-out that most of the drifters do not enter the YS along thehough they all belong to the mixed water of the easternaxis of the warm and saline tongue, but move toward theChinese seas. As mentioned above, both the TSWC waterChejudo or clockwise around the Chejudo (Fig. 6). Onand the TWC water in the cold season originate from thethese grounds, Korean scientists have thought that thereKuroshio. Thus, they are characterized by high S and highexists a mean current turning clockwise in the area westT. Especially, the core S of the TSWC water and the TWCand north of Chejudo， and the current is named thewater is usually larger than 34.3. However, the core S ofCWCI9. The previous studiesl20.21 indicate that the CWCthe YSWC water is mostly less than 34.0 since it mixeshas the following main features.(. i) The origin of the CwC is basically the same ascontinually with the water on its both sides in its north-ward flowing process. This fact implies that the YSWCthat of the YSWC. They all derive from the mixed waterwater is only a mixture of the TSWC water and the ECSregion formed by the TSWC water and the ECS conti-nental shelf water. This kind of mixed water, after enteringcontinental shelf water.the area west of Chejudo, is separated into two parts: one2 Cheju warm current中国煤化工0 to form the CwC, andTo inquire into the origin of the YSWC, the investi-the (; YSWC.gations and studies in the waters near Chejudo have beenTYHC N M H Gwater mass show that theenhanced by KORDI in recent years. While CTD meas-mixed water entering the area west of Chejudo can beurements were carried out, several satellite tracked driftersclassified into two types, the CWC water with aS > 34.0were deployed in the region near Chejudo with a purposeand the YSWC water with a relatively low S (33.0 < S <16Chinese Science Bulletin Vol. 48 Supp. June 200334.0). The CWC water is distributed around the Chejudoand intensifies obviously after entering the Cheju Straitand the YSWC water enters into the YS. The CWC waterwith a speed of mostly more than 10 cm/s and a maximumhas obvious seasonal variations. Fig. 7 ilustrates the dis-speed of 37 cm/s.tributions of the water types in the area near the Chejudoin different seasons. Of them, the water with 34.0 < S <34.5 is just the CWC water. It is shown from Fig. 7 thatKorean Peninsulathe CWC water advances toward the west by north andcan reach 124920-E in winter, retreats to the area east of125930-' in mid-spring and moves back to the near- shoreregion west of Chejudo in summer and even to the region342 34.0southeast of Chejudo in autumn. The seasonal variationsof the CWC water position are closely related to the9701changes of monsoon field and the extension of the97029601Changjiang Diluted Water toward Chejudo in summer.(i) The CWC flows usually into the western chan-1I 34.0nel of the Korea/Tsushima Strait after passing through the32°Cheju Strait and joins the TSWC eventually. The majorCWC path is located basically in water depths of more6975than 80 m near the Chejudo.124126°128° E( i) The observations show that the CWC west ofFig.6. Trajectories of sllite-tracked drifters and distributions of 34.0Chejudo is weak with a speed of mostly less than 10 cm/sisohaline.. I, February, 1997; . I, April, 1996.35 N3"CWC Water2835° N34°33 'CwC Water中国煤化工HCNMH G123°125°127°128 E124°125127"128 [Fig. 7. Seasonal distribution of the CWC water (after Lie et al, 2000).Chinese St亦数据/etin Vol. 48 Supp. June 20033 Coastal currentcurrent of about 10 cm/s, and the direction varied betweenAs the main component of the YS circulation, thenortheast and southeast to indicate an eastward flowingcoastal currents mainly include the YS coastal current, thecurrent. This observed result is very similar to that obKCC and the Liaonan coastal current. The latter is definedserved at mooring station M2 in April 1996 during China-as a current flowing southwestward along the south coastKorea joint investigation. A current meter mooring atof the Liaodong Peninsula in the northern YS. All theseStation M2 was deployed on April 7, 1996 and retrievedcoastal currents are characterized by lower S and lower Ton April 13, 1996. It is shown from Fig. 8 that the residualcurrent at 40 m depth was directed to the northeast in firstin the cold season.Some investigations and studies of the YS coastaltwo days and turned to the east since the third day. Thecurrent and the Liaonan coastal current have been carriedresidual current at 80 m depth was directed to the east byout5I). The observed data show that the direction of thenorth at beginning, but turned quite quickly toward thesoutheast after one day and kept to the end. In addition,Liaonan coastal current is quite stable and the currentseveral satellite-tracked surface drifters were releasedflows southwestward in four seasons. However, its speedduring China-Korea joint investigation. Fig. 4 in ref. [13and current width have obvious seasonal variations: theillustrates the trajectories of the satellite-tracked driftersspeed is high in summer and low in winter; the currentdeployed in April 1996. This figure shows that Drifterwidth is narrow in summer and wide in winter. In springNo.9605 deployed in the coastal region of Korea south ofand autumn, the current flowing from NE to SW is not36°N moved toward the north at a speed of about 4 cm/sobvious.in the first five days, then turned suddenly toward theThe YS coastal current, as a main flow in the YS,outh and accelerated obviously near 34940 -'N andmoves toward the east along the north coast of the Shang-reached 34°10-'N at a speed of about 9 cm/s. Obviously,dao Peninsula and turns toward the south or southwestthe flow shown by the drifter is a south-ward movement.near the Chengshantou, then goes toward the south φ-All these measured current data show that there reallyproximately along the 40- -50 m isobaths off the Haizhouexists a southward coastal current in the coastal regionBay after rounding Cape Chengshan and flows eventuallywest of the Korea Peninsula from winter to early spring,toward southeast in the area of 33°- 34°N. This path ofand the current is named the KCC. This current flowsthe YS coastal current is revealed quite clearly by thetoward the south approximately along the 40- -50 m iso-observations of the drift bottles and the drift cards rebaths west of the Korea Peninsula, then turns toward theleased by Institute of Oceanography, the Chinese Acade-east or southeast after reaching near 34°N and enters intomy of Sciences, during 1975 一1980124. However, thethe Cheju Strait along the north edge of the oceanic front.measured-current data in the eastern YS are quite scarceIts speed increases from north to south.compared with the observations in the western YS, which4 Conclusionsgreatly influences the understanding of the KCC.In recent years, KORDI (Korea Ocean Research andOn the basis of the above analyses, the schematicDevelopment Institute) and Florida State University c-pattern of the YS circulation in the cold season is shownployed several moorings in the eastern YS. Fig. 8 illus-in Fig. 9. It is shown from Fig.9 that the YS circulationtrates the observed current results at the mooring points inhas the following features: .the cold season of 1980191. All consecutive observations(1) The YS circulation in the cold season is com-lasted for more than one month. Station E2 (36°N,posed mainly of the YSWC moving toward the north in125930'E) is located in the nearshore region west of thethe central YS and the coastal currents flowing toward theKorea Peninsula, the residual current was quite weak withsouth on its both sides.a speed less than 3.0 cm/s and directed mostly to the south(2) The path of the YSWC has certain seasonal andat 20 m depth and 40 m depth. At Station E near Stationinterannual variations. The YSWC flows usually towardE2, the directions of the mean current were basically 10-the north along the 50 m isobath west of the YS troughward the south over the observation period (lasting moreand separates two branches near 35910- 'N, 123*30 E andthan 80 days). Station H, (34935'N, 12930'E) is located37°N, 124°E, respectively, which merge into the coastalin the coastal area southwest of the Korea Peninsula and iscurrents to move southward. The extension of the YSWC85 n mile from Stations E, and E. The residual currententers eventually the Bohai Sea.was directed basically toward the south over more than 40(3) The YSWC is not a direct branch of the TSWCdays at 20 m depth and 45 m depth with a speed of aboutor TWq bhntdarives frnm the mixed water region formed5 cm/s, stronger than those at Stations E, and E. A currentbyt中国煤化工s continental shelf water,meter mooring at Station MJ was deployed just north ofso thCHCNMHGrater.the strong front area from Feb. to Apr. 1986. Current dataobserved for two months show a relatively strong residualaround Chejudo, which is defined as the Cheju W arm1) See the footnote on page 12.18Chinese Science Bulletin Vol. 48 Supp. June 2003E(63/64 m)1_J03S06(8090100110Hs (20 m)乡yH, (45 m)ullliunE2(20 m)7E:(45m)M (60 m)5060120130140Time Qulian day)M2 (40 m)9809101102M,(80 m)9100 10110210397中国煤化工TYHCNMHGFig. 8. Residual current vectors at mooring stations.Chinese St亦数据/etin Vol. 48 Supp. June 2003. Guan, B. X., Patterm and structures of the current in Bohai,Huanghai and East China Seas, in Oceanology of China Seas (eds.BeijingZhou, D., Liang, Y. B., Zeng, C. K), Vol. 1, Dordrecht: Kluwer40^N- -Academic Pub., 1994,3- -16.5. Chen, Z. S., He, Y. C, Lin, X. F. et al, Current in the Yellow Sea,6. Lie, H. J. Wintertime temperature -salinity characteristics in thesoutheastern Huanghai (Yellow Sea), J, Oceanogr. Soc. Japan,1985, 41:291 298.. Beardsley, R. C, Limebumer, R., Kim, K. et al, Lagrangian flowobservations in the East China, Yellow and Japan Seas, La. Mer,1992, 30: 297- 314.8. Kondo, M., Oceanographic investigations of fishing ground in theEast China Sea and the Yellow Sea (_ )一- -Characteristics of theShanghaimean temperature and salinity distributions measured at 50 m30depth and near the bottom, Bull. Seikai Reg. Fish Lab., 1985, 62:). Lie, H. J., On the Huanghai (Yellow) Sea circulation: A review bycurrent measurements, Acta Oceanologica Sinica, 1999, 18(3):7355 - -374.10. Hsueh, Y., Recent current observations in the eastern Yellow Sea,25 。J. Geophys. Res., 1988, 93: 6875 - 6884.11. Tang,Y.X.Zou, E. M, Lie, H. J. et al, Analysis of hydrographicTaiwanfeatures and circulation situation in the southerm Yellow Sea inearly spring, Acta Oceanologica Sinica (in Chinese), 1999, 21(5): .2012. Tang, Y. X., Zou, E. M., Lie, H. J. et al, Some features of circula-tion in the southern Yellow Sea, Acta Oceanologica Sinica (inChinese), 2000, 22(1): 1-16.3. Tang, Y. x, Zou, E. M.. Lie, H. J. et al, On the origin and path ofthe Yelloe Sea Warm Current during winter and early spring, Acta15 iOceanologica Sinica (in Chinese), 2001, 23(1): 1 -12.115120°125°130 E14. Yuan, Y. L.. Guo, B. H., Sun, X. P., Physical oceanography in pan-Yellow Sea region, Journal Oceanography of Huanghai & BohaiFig. 9. Schematic pattern of circulation in the YS and ECS in the coldSeas (in Chinese), 1993, 11(3):1 -season. 1, Minzhe coastal current; 2, Taiwan warm current; 3, Kuroshio;5. Guo, B. H, Major features of the physical oceanography in the4, Tsushima warm current; 5,Yellow Sea warm current; 6, Yellow SeaYellow Sea, Journal of Oceanography of Huanghai & Bohai Seascoastal current; 7, Korea coastal current; 8, Cheju warm current; 9,(in Chinese), 1993, 11(3):7- -18.Liaonan coastal current.16. Le, K. T, Mao, H. L, Wintertime structure of temperature andCurrent (CWC). The origin of the CWC is basically thesalinity of the southern Yellow Sea and its current system,Oceanologica et Limnologia Sinica (in Chinese), 1990, 21(6): 505same as that of the YSWC. The main stream of CWC islocated in water depths of more than 80 m near Chejudo.17. Fang, Y., Zhang, Q. H, Fang, G. H, A numerical study on theIts speed is usually less them 10 cm/s west of Chejudo andpath and origin of the Yellow Sea Warm Current, The Yellow Sea,increases obviously after entering the Cheju Strait.1997,2:18 - 26.(5) The KCC flows southward roughly along the 4018. Su, Y. S., A survey of oceanographical environment and circula-tion system in the Yellow Sea and East China Sea, Journal of-50 m isobaths west of the Korea Peninsula and turns inOcean University of Qingdao (in Chinese), 1989, 19(1): 146- -158.general toward the east or southeast after arriving 34°N19. Le, K. T. On the origin of the Yelloe Sea Warm Current water,and finally enters the Cheju Strait. The speed of the CWCActa Oceanologica Sinica (in Chinese), 1992, 14(2): 9-19.increases from north to south and is about 10 cm/s near20. Lie, H.J,Lee, S., Lee,J. H. et al., Is the Yellow Sea Warm Cur34°N.rent a persistent mean flow? in Intermational Symposium on Prcgress in Coastal Engineering and Oceanography, September9 - -11,Acknowledgements This work was supported by the project“China-Korea Joint Study on Sedimentary Dynamics and Paleoenvironments in21. Lie, H. J., Cho, C. H., Lee, J. 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