Study on interaction between the coastal water,shelf water and Kuroshio water in the Huanghai Sea an

Acta Cenolopica Sinica, Vol. 22. No. 3, pp. 351-~ 367, 2003.ISSN 0253 505XPublished by China Ocean Press.Study on interaction between the coastal water, shelf water andKuroshio water in the Huanghai Sea and East China Sea *Binghuo Guol , Xiaomin Hu' , Xuejun Xiong' , Renfeng Ge'(Reeired March 10, 2003; aceped June 10, 2003)Ahstract一The main proesses of interaction between the coastal water, shelf water and Kuroshiowater in the Huanghai Sea (HS) and East China Sea (ECS) are analyzed based on the observation andstudy resuts in recent years. These proeses include the intrusion of the Kurohio water into the shelfarea of the ECS, the entrainment of the shelf water into the Kuroshio, the seasonal process in the south-em shelf area of the ECS crntolld alternatively by the Taiwan Strait water and the Kurshio water in-truding into the shelf atea, the interction between the Kuroshio branch water, shelf mixed water andmodified coastal water in the northeastem ECS, the water exchange between the HS and ECS and thespread of the Changjiang diluted water.Key words Huanghai Sea, East China Sea, coastal water, sbelf water, Kuroshio water, interactionINTRODUCTIONIt has been shown from the thermohaline characteristic analysis and water masses divisionof the HS and ECS that there are three major water masses in the HS and ECS, and they are(1) the coastal water, that is located in the continental coastal water area and the water area offthe west coast of the Korea Peninsula with a basic feature of low salinity and is characteristic oflow temperature in winter; (2) the Kuroshio water, that is located in the Okinawa Trough ofthe ECS andisa warm and saline water; (3) the shelf mixed water, a mixed water of thecoestal water and Kuroshio water, occupies the extensive shelf water area. The interaction be-tween the three water masses and their seasonal variations constitute cormplex marine dynamicprocesses and control the space- time structures of marine environments in the HS and ECS.The nutrients and suspended matter carried by the water masses feed different planktons andeconomic fishes, and the pollutants carried by them also generate adverse impact on the marineenvironment. The interaction and exchange between the three water masses govern the trans-portation, dispersion and settlement of sediments into the sea and bring about the inhomogene-* This stuty was supred by the National Thenatie Prjeat of Marine Surveys and the Nationl Mejor Fundemental Re-search and Development Prjet of Chin under contract No. G1999 - 043802.1. First Institute of Oceanography, State Oceanic Adninstration, Qingdeo 266061, Chine中国煤化工MYHCNMHG352Binghuo Guo et al.ity of marine resource spatial distibution, so the understanding of these processes will providescientific basis for the marine environmental protection. In this paper, the study results in thisfield in recent years are summarized, and the main interaction processes of the three watermasses in the HS and ECS are described.INTRUSION OF THE KUROSHIO INIO THE ECS SHELF AND ENTRAINMENTOF SHELF WATER INTO THE KUROSHIOThe Kuroshio is a farnous western boundary curent, the North Equatorial Current is sepa-rated into two branches after meeting the western boundary barrier consisting of the Philippinesand China' s Taiwan Island, the southward branch is the Mindanao Current, and the north-ward branch is the Kuroshio. The Kuroshio flows over the Yilan Ridge and enters the ECS,then flows northeastward along the shelf slope, and flows out of the ECS from the TokaraStrait. Influenced by the topography, the Kuroshio has two significant meanders, one is locat-ed in the water area northeast of the Taiwan Island, and the other is located in the water areasouthwest of the Kyushu Island (29° ~ :30°N, and 127 *30' ~ 128*30 E), and the two areas are .places with the strongest water exchange between the Kuroshio water and shelf water.120° 121°122*123° 1241259126°127°E9°+NR°270100260.25° -4°t93206179320618 ,30，832062022°Fig. 1. Teietories of the Argos drifters deployed off the east coast of Taiwan Island in November 17, 1994.Intrusion of the Kuroshio northeast of Taivan IslandThe Kuroshio Current northeast of the Taiwan Island is obstructed by the east - westtrend shelf slope, which results in the intrusion of the Kuroshio water into the shelf area. It is中国煤化工MYHCNMHGInteraction between the water masses in the HS and ECS353shown from the trjectories of stllite-tracked surface drifers in Fig.1 that the current intrud-ing into the shelf area in winter is located in the northern Mianhua Canyon, the current patternis similar to the three branches of the canyon and has three paths: (1) most of seawater flowsanticylonically and finally returns to the Kuroshio; (2) a part of seawater flows northwest-ward, then flows northeastward along the 100 m isobath, and returms to the Kuroshio and be-comnes a branch of the Taiwan Warm Current; (3) the other part forms a cyclonic eddy in thesea area northeast of Taiwan Island. The first and the second path in summer seldom Occurs,but the third path is prominent, which will be described in details in the next section.Separation of the Kuroshio water soutruest of KyishuAfter leaving from the shelf slope in the area 29° ~ 30* N southwest of Kyushi，theKuroshio traversing the Okinawa Trough flows out of the ECS from the Tokara Strait, and an-other Kuroshio branch is often separated from this Kuroshio section. Most of the branch seawa-ter forms an anticyclonic eddy west of Kyuishu, resulting in the seawater accurmulation in thesea area, which in turn forces the Kuroshio to change its direction; another part of the branchseawater intrudes into the shelf area and becomes an origin of the Tsushima Warm Current(Figs 2 and 3), and the seawater accumulation west of Kyushu results in the sea surface slopedown to the west, which favours the formation of a northward Tsushima Warm Current.It is shown from some study results that the separation of the Kuroshio branch may havetwo dynamic mechanisms: the large scale one and the meso-scale one, i.e., (1) the Kuroshio130*E6°叶40 cn/s3418(5/9)2° t(31/8):30 t201781 1628° tFig. 2. Triectores of the Argos drifters deployed by theKorea Ocean Research & Development Istitute in Augustto September 1994.中国煤化工MYHCNMHG354Binghuo Guo et al.1200122°124°126°128°130°:2° -N30°_8°.6°.24°-Fig. 3. Schematic diagrum of the exchange between the Kurushio water and shelf water.frontal eddy and warm filament pattern (Guo et al., 1998; Guoet al., 1991) and (2) thejoint dynamic mechanism of baroclinic current and bottom topographic rising west of Kyishu(Hsueh et al., 1996). Guo et al. (1992) and Song and Guo (1996) calculated the geostrophiccurrent on the 129 E section and found that there was a westward countercurrent north of theKuroshio, which indicates the existence of this mechanism.Role of the Kuroshio frontal eddy in the water exchangeThe Kuroshio in its central section of the ECS flows along the shelf slope with a compara-tive straight path, but the baroclinic instability of the Kuroshio Current induces the frontalshear wave, and the nonlinear effect makes the shear wave generate the entrainment, form thefrontal eddy and warmn filament structures, which bring the Kuroshio water to the shelf area tomix with the shelf water there (Fig.3). On the other hand, the frontal eddy also entrains theshelf mixed water into the Kuroshio, so it is shown from the salinity profiles on the cross-Kuroshio section that the bigh salinity Kuroshio water mingles often with the isolated low salin-ity water masses. It is shown from the calculated results (Guo and Ge, 1997) that the watertransport exchange between the Kuroshio water and shelf water in the ECS is that the Kuroshiowater transported into the shelf area is 0.4X 106 m'/s, and the shelf water entrained into theKuroshio is 1.8X 10 m' /s, almost comparative to the anpual volume transport of the TaiwanWarm Current. It is shown from the satellite IR images that the entrainment of the shelf waterinto the Kuroshio occurs significantly in the area near Chiwei Islet and the Kuroshio right-turn-ing place (29°~ 30°N) (see Fig.4).中国煤化工MYHCNMHGInteraction between the water masses in the HS and ECS35517 127 12%" 120” 129 132E11*158 E:132421.Fig. 4. Setllitc IR images on January 26, 1999 (a) and on March 22, 2001 (b).INTERACTION BETWEEN THE TAIWAN STRAIT WATER AND THE INTRUDING; KUROSHIO WATERThe Taiwan Strait is one of the ECS water inlets, and the Taiwan Strait Current is con-trolled by the East Asian monsoon with obvious seasonal variations, so its influence on the ECSalso has strong seasonal characteristics.Under the actions of northerly wind in winter, the low temperature and low salinity Zhe -Min (Zhejiang - Fujian) coastal water consisting mainly of the Changjiang River runoff flowssouthward along the ooast, meets the warm and saline water coming from the SCS in the north-ern Taiwan Strait and the two waters are mixed up to form a modified coastal water mass. It isshown from the survey results in January 1999 and the satellite IR image (Fig.4a) that themodified water mass had a water temperature of 15~17 C, a salinity of about 33.0 and a cy-clonic circulation along with it, and the trajectories of Argos drifter deployed in March 2001verified the existence of this water mass (see Fig.5). Therefore, it is considered that the Tai-wan Strait water in winter is limited to the inshore area northwest of Taiwan Island, makesless contribution to the Taiwan Warmn Current, and the extensive shelf area of the southernECS is fully controlled by the intruding Kuroshio water (Guo et al., 2000).In spring, the warm and saline water south of Taiwan lsland flows gradually to the northwith the weakening of the northeast monsoon from mid-March on. It is shown from the satel-lite IR image on March 22, 2001 that a warm water tongue off the west coast of Taiwan Islandspread northward into the ECS and reached about 27°N, and there was a low temperature wa-ter zone between the Taiwan Strait water and the Kuroshio water northeast of Taiwan Island中国煤化工MYHCNMHG356Binghuo Guo et al.119.0 119.50 120.0 120.s9 121.0 121.50 122.0 122.5°元 .27.00N26.5026.0025.5025.024.5924.0Fig. 5. Trmjectories of Argos drilers deployed on March 25, 2001.intruding into the shelf area, which indicates that the two waters have their respective indepen-dent patterns ( see Fig . 4b). The modified coastal water mass in the northern Taiwan Strait dis-appeared with the change from the northeast monsoon to the southwest monsoon, the warmwater coming from the southern Taiwan Strait quickly advanced to the ECS, and the Kuroshiowater intruding into the shelf area from the sea area northeast of Taiwan Island gradually re-treated to the deep water area. The front of the strait warm water at depths less than 50 m inMay reached about 30°N (see Fig.6), but the strait warm water couldn' t sink to the bottomlayer of the ECS because of the shallow strait (water depth is less than 70 m) and the low den-sity of the strait water，and the bottom warm water was limited to the Minbei (North Fujian)coastal area south of 27°N, so the bottom water on the extensive ECS shelf was still theKuroshio water (Guo et al., 2000). It is shown from Fig.7 that there were double- thermo-clines and double-pycnoclines in the place occupied by the strait warm water, namely, the up-per thermocline caused by the thermodynamic and wind stirring, and the lower thermoclineformed by the superposition of the strait warm water on the bottom Kuroshio water.In summer, the Kuroshio water was basically limited to the shelf slope area and flowednortheastward except that part of the Kuroshio water was brought into the shelf area by the cy-clonic eddy northeast of Taiwan Island. The strait warm water became the main∞omponent ofthe Taiwan Warm Current, mixed with the Zhe - Min coastal water to flow northward to theChangjiang River mouth area, and its upper layer water gradually separated from the mainstream to spread eastward in its northward flowing process and occupied the upper layer of thesouthern ECS shelf sea area (see Fig.8). The near-bottomn water was still the Kuroshio water,was driven by the Ekman shoreward current to approach the coast, and ascended on the bottomslope of Zhejiang inshore area to form the Zhejiang coastal upwelling; in the meantime, thebottom cold water spread to further north to reach the Changjiang River mouth area (see中国煤化工MYHCNMHGInteraction between the water masses in the HS and ECS35712012122°124° 126°. 128E311°9272:120° 1220 124° 126° 128°FE. 120122”124° 126° 128° EN270o25°22°124° 126° 128°E20P1220124*26°128°E .31°形2925°-25° tFig. 6. Distributions of surface, 50 m depth and bottom tcmpcrature (C) (left figure) andsalinity (right figure) in spring.Fig.8). In addition, the double- thermocline zone ocurring in the southerm ECS was furthernorth in summer than in spring.In autumn, the southwest monsoon changes gradually to the northeast monsoon, and thetemperature and salinity distributions in the southern ECS in autumn (November) are similarto those in spring. The Taiwan Strait outflow weakened, the water tongue front returned toabout 29°N, and a comparatively low temperature zone occurred again between the TaiwanWarm Current and the Kuroshio (see Fig.9). The convectional mixing due to the drop in sur-face temperature in autumn made the double-thermocline zone disappear, there was only thelower thermocline, and the Kuroshio water force intruding into the shelf area was strengthenedwith the weakening of the Taiwan Strait outflow.中国煤化工MYHCNMHG358Binghuo Guo et al.J19 120 121%. 122* 123° 1249.125° 1269 127° 128° 129°E370 |6° t4° Ipo' thermo-3° {yeline area320100° .8°270]6°!Fig. 7. Thernodline depth dstibutions (May 1998). Soid lines arte the upper themocine, dahed lines are the lowerthermocline, and there are doubl-hermnoclines in the solid and deshed line superposition area.INTERACTION BETWEEN THE NORTHEASTERN FCS 00ASTAL MODIFTED WATER,ECS SHELF MIXED WATER AND KUROSHIO BRANCH WATERThe water area south of the Cheju Island in the northeastern ECS is a confluence area ofthe modified coastal water, ECS mixed water and Kuroshio branch water, the interaction be-tween the three waters is complex, and they have obvious seasonal variations.[n winter, the northertly monsoon drived the Subei (North Jiangsu) coastal water south-eastward to intrude into the northern ECS and to mix with the ECS shelf water to form a lowsalinity and temperature water tongue. It is shown from Fig. 10a that the water tongue frontspread eastward to reach the area near the 100 m isobath and southward to reach about 30"N,the Kuroshio branch (the Tsushima Warm Current) water occupied the water area east of the100 m isobath, and the water exchange between the shelf mixed water and Kuroshio branchwater was weak because of the strong front between the two water systems.In spring, the coastal water consisting mainly of the Changiang diluted water graduallyturned from the south to the east, the modified water flowed around the edge of the above-mentioned low temperature water tongue and began to affect the water area south of the ChejuIsland and gradually flowed northward, in the meantime, the Kuroshio branch water graduallyshifted eastward.中国煤化工MYHCNMHGInteraction between the water masses in the HS and ECS35912(24°126° 128K 120°122°124° 126°128.31°20、29-25°↓2S120*22° 124°126° 128°E; 120° 122° 124° 126°128*E31N29929027050↓25122° 1240126° 128°F1209 122°124° 126° 128°E310.31°-9°29*27°2759. lFig. 8. Distributions of surfaece, 50 m depth and botomn tetmperaturte (C) (left figure) andsalinity (ight figure) in summer (August 1998).In summer, the coastal water spread to the east by north, extensively affecting the near-surface layer of the water area near the Cheju Island and even the Korea/Tsushima Strait, theintermediate water was the shelf mixed water, the near-bottom water was the Kuroshio branchwater, and the superposition of the three water masses formed the double thermoclines andhaloclines (among them, the double -haloclines were obvious, and the double- thermoclines wereincorporated (see Fig.11). There was an obvious front between the shelf mixed water and theTsushima Warm Current water, which indicates that the horizontal mixing between the twowater masses is not strong.In autumn，with the change of monsoon the modified coastal water quickly retreatedshoreward, and the shelf mixed water also retreated westward; the Kuroshio branch made中国煤化工MYHCNMHG360Binghuo Guo et al.120*122° 124°126° 128E120° 122°， 124°. 126° 128E31°310Ns9°292727°25°↓-25°120”，122° 124°126°，128°K，70@259↓2526° 128E31Ci /w290Pig. 9. Iistributions of surface, 50 m depth and botom ternperature (C) (let figure) and slinit (right figure)in autumn (November 1997).more contribution to the Tsushima W arm Current, the salinity in the water area south of theCheju Island increased quickly from 33.0~ 34.0 in late October to 34.0~ 34.6 in mid-Novem-ber (see Fig. 12), and the Tsushima Warm Current water had basic characteristics of the sur-face Kuroshio water by December.WATER EXCHANGE BETWEEN THE HS AND ECSIn winter, driven by the northerly monsoon the Subei coastal water with a termperaturelower than6 C and a salinity less than 31.0 flowed southward, turned to the southeast by theblocking of Changiang Bank to intrude into the northern ECS, and mixed with the ECS water中国煤化工MYHCNMHGInteraction between the water masses in the HS and FCS361120126°128°E 120012:124°8° +8t6°-6°34°32°-2°30°-Fig. 10，Surface temperature (C ) (left figure) and salinity (night figure) distributions in winter (January 1999).Sution No.301B02BCB0406B08 B09B1050100一18150-02040km20001B03B04 B0SB07R0934.4- -E三出150201bFig. 11. Salinity distributions along the 3I'45 'section (Septcmber 1994).中国煤化工MYHCNMHGBinghuo Guo et al.124°31.071435z 825-179- 18*E124125°，126°17°，128E二5.50} t二100150 24 Oeober 199!1150- 15 Nowember19911Fig. 12. Salinity dsributiuns alog the 32*30 'N setin during two suveys.to be modified during this prucess, and finally showed a tongue-like pattern; as a water com-pensation, the warm and saline Huanghai Warm Current (HWC) water intruded into the areawest of the HS Trough, and the two waters constituted a S shaped water exchange pattern (seeFig. 10). The temperature and salinity at the frontier o[ low temperature and salinity watertongue intruding into the northern ECS were 15~ 17 C and 33.5~ 34.0, respectively, andthe frontier could reach 126° 30' E on the east and 30°N on the south. As for the water massproperty, the water in the water tongue core area belongs to the low temperature and low salin-ity modified coastal water, and the water at the water tongue frontier belongs to the HS andECS mixed water.In spring, the thermocline in the offshore water area was gradually formed, the tempera-ture in the upper sea increased quickly, and the increase in water temperature was quicker inthe inshore area than in the offshore area; in the meantime，because the northeast monsoonchanged gradually to the southwest monsoon, the Subei coastal water retreated, the northwardflowing Taiwan Warm Current was intensified to affect the area beyond the Changjiang Rivermouth, the low temperature and low salinity water tongue intruding into the northerm ECS inwinter became indistinct in the surface layer (0~ 10 m), and the more stable salinity distribu-tions at depths of more than 30 m were still tongue-like, but it is shown from the temperaturedistributions that there was an almost closed cold water area (the northern ECS cold water) inthe area southwest of the Cheju Island. There was also a cyclonic circulation along with the coldwater，which enabled the cold water mass to be retained for a long time, and the cyclonic cir-culation is also called cold eddy. The HWC water intruding into the southern HS was cut off toform an isolated warm water mass, but it remained only for a short time, from about April toMay due to the lack of associated circulation, so a temperature distribution pattern occurredwith a cold water mass and a warm water mass lying south and north of the line connecting theChangjiang River mouth and the Cheju Island, respectively (see Fig. 13).In summer, the Taiwan Warm Current was continuously intensified to drive the northernECS cold eddy eastward, the cold eddy range constantly decreased due to the water mixing,and the cold eddy disappeared by autumn. In autumn, a front occurred near the line connectingthe Changjiang River mouth and the Cheju Island, the western half of the front was dominatedby the salinity front, and the eastern half was dominated by the temperature front (see Fig. 14)，中国煤化工MYHCNMHGInteraction between the water masses in the HS and ECS363126°128°E 120°122*124°128E388o +N36°6°+。35340 .4°七jis@300产迎恩Fg. 13. Tenperature (C) dstributions at 30 m depth in spring (May 1998) (et figure) and bottomslinity dsttibutions in summer (August 1998) (right figure).123821,36° 5o36°0 sJ1514>143434°203222Fig. 14. Horiontal dstributions of temperature (T) (solid line) and selinity (ashed line) at 10 m depth(a) and in bottom layer (b) (October 1996).which indicates that there was almost no water exchange between the HS and ECS in autumn.From late autumn and early winter on, a new round of water exchange process between the HSand ECS began.SPREADING OP CHANGJIANG DILUTED WAIERThe Changjiang diluted water is one of important hydrographic features in the surface layerin summer, and its main feature is that the ECS coastal curent mixes with the Changjiang Riv-er and Qiantang River runoffs in the northward flowing process to form a strong diluted water中国煤化工MYHCNMHG364Binghuo Guo et al .in the sea area off the Changiang River mouth, the water tongue is generally directed to thenortheast, and its spreading is far and extensive, but some anomalous events xcurred, for ex-ample, the water tongue direcions in August, 1975, 1982 and 1984 turned to the north (1inetal., 1985). It is shown from the surface salinity distributions in August 1998 (Fig. 15b)that the catastrophic flood in the Changjiang River valley occurred in August 1998， theChangjiang River runoff rushed to the southeast from the Changjiang River mouth, and thenturned to the northeast at about 31'N, 12230'E to flow to the Cheju Island, and formned a di-luted water tongue. The salinity in the sea area off the river mouth was less than 6.0, the corearea of the diluted water( S <26.0) reached as far as 2530 E, the diluted water tongue couldspread out to the extensive water area south of the Cheju Island, the water area with a surfacesalinity less than 27.0 reached beyond 127* 30' E and spread southeastward to the Kuroshiomain stream area, and the salinity of the Kuroshio surface water decreased to31.0~ 32.4.1226°128°K120124°126°128°EN36036°书20/3302534H四ce20卡、28.020(29.0元300300Fig. 15. Changjiang diluted water spreading pttrm. a. May 1998 and b. August 1998.Based on the Changjiang diluted water spreading patterms observed in August 1998 andshown by the historic data, the spreading process can be divided into three stages (Zou et al.,2001). The first stage is the turning stage, and the turning points are located all in the rivermouth area west of 122*30 E, where is some distance to the Taiwan Warm Current east ofZhoushan Islands, so the reason for the diluted water turning is not the pushing-up of the Tai-wan Warm Current. In fact, the southernly wind in summer drives the Zhejiang coastal currentnorthward to block the southward diluted water, so the northward Zhejiang coastal current isthe basic reason for the Changjiang diluted water turning; and the Zhejiang coastal current inwinter flows southward along the coast, so the Changjiang diluted water becomes the basiccomponent of the coastal current. In addition, the Changjiang River runoff flows into the seawith a mighty momentum, and its discharge magnitude will influence the turming positon of the中国煤化工MYHCNMHGInteraction between the water masses in the HS and ECS365diluted water. The second stage is the spreading stage, the northward Taiwan W arm Currentmeets with the southward Subei coastal current in the sea area east of the Changjiang Rivermouth and turns to the east, and the spreading direction of the diluted water is dependent onthe relative strength of the two currents, but the diluted water tongue still retains its entirelykinematic characteristics, and the diluted water flow regime in the near- surface layer is signif-cantly diferent from the underneath background current field. The third stage is the dispersionstage, the diluted water moving direction has entrely been combined into the background cur-rent field, for example, the diluted water makes a cyclonic movement in the water area south-west of the Cheju Island, then extensively spreads to the surface layer in the Tsushima WarmCurrent area, spreads southeastward to affect the Kuroshio surface water north of 28* 30'N,and makes the surface salinity there decrease to less than 32.0.It is noticeable that the Changjiang runoff in May 1998 was greater than normal, the di-luted water first spread southeastward, then turned to the east by north, finally flowed alongwith the background current field, namely, flowed along the outer edge of the northern ECScold eddy to form a semiannular low salinity water zone, which well indicates the path of thebackground main stream in the northerm ECS ( see Fig. 15a). The Changjiang diluted waterhad an obvious interaction with the background current field in the whole spreading process.The diluted water in the turning area was cyclonic so that the Taiwan Current water wasintensified to intrude into the sea area off the Changjiang River mouth, and a cold eddy wasgenerated at depths of more than 5 m. The Taiwan Warm Current turned clockwise in the wa-ter area near 32*N, 124930'E, which results in the sinking of Changjiang diluted water and itsthickness increasing to 10 m (Fig. 16).10一302030官4060708090100HY 126,Angunt 1998L s0km ;110Fg.16. Salinity distibutions along Section FG off the Changjiang River mouth.中国煤化工MHCNMHG366Binghuo Guo et al .The Changjiang diluted water in autumn (November 1997) spread southward to the waterarea southeast of the Zhoushan Islands with a weak force, and the Changjiang diluted water inwinter flowed southward along the Zhejiang coast under the actions of the northerly wind.In summary, the seasonal variations in the Changjiang diluted water spreading directionare considerable, and the inflvence range of the diluted water covers most of the FCS waterarea. The diluted water in winter flows southward along the Zhejiang and Fujian coast, its ;flowing direction changes gradually from south to north after spring begins, it reaches about 30°N in May, flows toward the Cheju Island in summer to enter the southern HS in some years,and the diluted water spreading direction changes from north to south after autumn begins,which indicates that the surface layer of the whole ECS shelf area is influenced by theChangjiang diluted water (including the Zhe - Min coastal water), and its influence range inthe years with large Changjiang River runoff volume could spread to the northern sea area of theOkinawa Trough.INTRUSION OF THE LUTBFI COASTAL WATER INTO THE SOUTHERN HSIn winter, the Bohai Sea water is driven by the northerly monsoon to generate an eastwardcurrent along the northern Shandong coast, this current is called the Lubei (North Shandong)24.00、25.00、 26.00 24.00 25.00， 26.00 。，24.0 25.00 26.00031.032.0033.005 31.00 32.000 33.00S 31.00 32.00 3.0 s4005006.0700 1(C) 4005.00 6.00 7.00 1(C)5.00 6.00 7.00 8.00 (心)10-0-20-营30-0F4010 tsoL 36*0.1'N,122*0.0'E50L 3.0.01215.202359599'N,1229299'E24.0025.0024.50 25.50， 26.5031.0032.00 33.30 $ 31,0032.003300 32.00 33.00 34.00 <5.00 6.00 7.00 8.00 900 (T) 5.00 6.00 7.008.00 9.0006.00 7.00 8.009.00 T0.00 (C)1002030-t 3040 tsoL 35*0.0' N,121*45.0'E50L 3590.0' N,1220.0'Eso350.0',12230.0E | 1Fig. 17. Intermediale cold water phenomenon in the water are south of the Shandong Peninsula in spring[Adapted from Zou et al. (000].中国煤化工MYHCNMHGInteraction between the water masses in the HS and ECS367coastal current, and rounds the east cape of Shandong Peninsula to intrude into the southem HSand form an accumulated water mass in the sea area south of the Shandong Peninsula. The wa-ter mass gradually forms a thermocline under the thermodynamic actions after spring begins,and moves eastward due to the weakened HWC water to superpose on the HWC lower water togenerate the intermediate cold water (see Fig. 17) (Zou et al., 2000); the intermediate coldwater phenomenon occurs only in early spring (April), and this phenomenon will disappearwhen the intermediate water temperature is greater than the lower water temperature due tothe vertical mixing.REFERENCESGuo Binghuo, Ge Renfeng (1997) Role of the Kuroshio frontal eddy in exchange between the shelf water and Kuroshio water inthe Fast China Sea. 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