ANumeriealExperimentontheCoastall王fぎeets OntheWesternBoundaryCurrent． Part T Effect ofInclined Coastline YoshihikoSEKINEandAkiyaAso

Bull．Fae．Bioresources，MieUniv．  

No．14：25仙50   Mareh25．1995  

ANumeriealExperimentontheCoastall王fぎeets  

OntheWesternBoundaryCurrent．  

Part T Effect ofInclined Coastline   YoshihikoSEKINEandAkiyaAso  

FaeulyofBior￠＄OureeS．MieUniversiもy  

Abstraet  

Effectorcoastaltopographyonthewesternboundary currentis studied by use ofa   barotropic numericalmodelwith specialreference to the effect ofinclination of the  

northernboundary．Chaoticchangefrorn rneanderpattern to straight flow pattern  

OCCurSinthe case wiもb theinclinaもion orlOO and rela抗vely smalleddy viscosity・  

Straightflowpatternhasatendencytoappearinthecaseswiththelargeinclinationor  

thenorthernboundaryfromzonaldirection．  

1．lntrodueion  

TheIくuroshio，the＼VeSternboundarycurrentinNorthPacifichasapeculiarnatureandsho＼＼・Sbimodal   pathcharacteristics：aStl・aightpathandalarどemeanderpath ． ．suchlargemeanderpathis not   Observ￠dintheGulfStreamSystemandotherwesもernboundarycurrents−）．でhel且rgemeanderinもhe   Iくuroshiohasbeenstudiedbymanyinvestigators，andithasbeensho＼Vnthatthelarge meander ofthe  

IくuroshiohasacharacterofastationaryRossbywa＼reinthezonalflowandthattheconfigurationofthe  

almosteastward，andaRossbywavecanbeeasilygeneratedthere．Inthepresentstudy，thecoastline  

issimplifiedasshownin Fig．land thecoastsouthofJapan wi11becalled as a northern coastfor  

Simplicity．  

Inearlystudies＝），it was ar糾ed thaもthe Xuroshio takeslar卵meander pa払whenits volume   tran8pOrもand／oreurr和もvelocityi5relatively smallwhileinlater studiesl卜川，七hat the Kuroshio  

takesthelargemeanderpathwhenthevolumetransportisrelativelylarge．Thedifferencebetweenthese   twogroupsiswhetherinclusionof the effect of the north coast from the zonaldirectionis takeninto   accountinthelaterstudiesornottakenintoaccountintheearlystudies．   

Sぬineユ才）examinedtheefrectoど払einclinaもionof払enorthcoast，andshowedthatthewesもernboundary  

CurTentisunstableandameanderingflowisformedwhenitflowszona11y．Incontrast，ifthenorthern   

26  

COaStincline＄COnSid￠rably￡romtbezonaldirection，thecurrenもisstableandrlowsina8もraightpatb   patもernalongcoast．Inもhepreviou8paper12），however，thenoれherncoastinthemeridionaldirection   COl、1・CSPOndingtothccasterncoastofHonshu，Japan＼ヾaSnOlincludedinthemodel．1nLhispapcr，the   Cfrccto＝hei一一Clinationofth＝10rLhcoastwillbcexamiIICdrurthcr．ineludingthe】10rthol、11COaStiIlthe  

modelshowninFig．1．  

g．Numeriealmodel  

AhomogeneousoceanwithadepthoflOOOrnisassumcd．WeadoptaCartesiancoordinatesystemon  

aβplanewithx−aXisもoeast，y−aXisto north．でhe verticallyin七曜rated equations under rigidlid   approximaもionandhydrostatiebalancearetransformedintothevorもicityequaもion：  

∂之   ∂㍑Z   ∂ぴZ  

∂￡   ∂￡   ∂ッ   ーβu＋ん∇gz，  

技芸）十￡覧霊）．（2）   

∂u   ∂㍑   ∂  

■         ＝＝  

∂焉  ∂ッ  ∂∬  

Thesyrnb01susedinLheabo＼・eequationsare tabulatedin Tablel．The systernis dri＼・en byin−and   Ouぱlowwま痛avoiumeとransporもOf55Sv（ユSv＝1012cm3s8C−1）．Inflowisgivenatthesouthernboundary  

andoutflowatthecasternboundary．Sinusoidalhorizontalvelocitydisもributionofthein−andoutflow   isassumeda】1do】11yr）OrもhwardvelocitycomporlenもisglV8natthesouthernopenboundary：  

針＝翫−￠ocos（汀Ⅹ／Li） roヱⅧ≦Ⅹ≦し （3−1），  

for Li s xx  （3−2），  

￠三2￠。  

＼＼，hcre4・oisahalforthetotaltransport ofthein−and outflo＼＼▼aIld L．（＝187km）is thewidth ofthe   inflow（Fig．1）．でheSまmilarboundaryconditionisimposedattheeasternoutrlowboundary．  

￠＝2￠。  

￠＝￠0−￠8eOS（方（y叫1020．5）／Lo）紬r lO20．5km≦y   

（4−2），  

WhereLo（＝157km）isthewidthof the outflow．Viscous boundary conditionisimposed on the   northernboundar）Tandslipconditionisimposedontheothersboundaris．lnthenumericalcalculation，  

、Ve adopt a rectangulargrid with horizontalspacing or18．7kmin、VeSt−eaSt direction and15．7kmin  

southnorth direction．  

In the present study，eight cases of numericalexperiments with different modeleharacter are  

performed（Table2）．Firstl〉・，arelativelysmalleddy＼・iscosity withAh＝ 5×106cm＝sec−1is assumed  

andcoastaLtopographice［（eclisexaminedbyuseo［［ourmodelswithdifferentinelina亡ion ofnorthern   

Coastaltopog・rapllieefrecもSOnWeSternboundarycurrenも．Ⅰ  

27  

boundELr）・from zonaldirection（Fig．1）．ModcIs＼＼・ith theinelinaLion from zonaldircctioIl（Oin  

ダig．1）withOO，100，200and300arerererredtoasVOOS壬王，VlOS】∃，V20SE and V30SE，r8SpeCtiv￠1y  

（Table，2）・Secondly，Similarrourexperim￠ntSareperrOrmedassumin官relativelylarge￠ddyviscosity  

Withん−＝1×107cm2sec仙l，Ofwhichfourmodelswiththesimilarinclina症onorthenorもhernboundary  

fromzonaldirecもionarerererredtoasVOOLI王，VlOLE，V20LE，andV30LE，reSpeCtively．  

でablel工．istof＄ymboIs  

t ：tiIlle   

X：eaStWardcomponentofCartesiancoordinate   y：nOrthwardeomponentofCartesiancoordinate  

u：Ⅹ−directed（eastward）componenもorhorizontalveloeiもy   v：y・directed（northward）componentorborizontalvelociもy  

d：depthoftheoeean  

Z：relativevorticity  

￠：＼∫01umclransportfunction  

β：1inearchangerateortheCorま01isparam8ter（β＝2×10…13cm肌Isec−1）  

Ah：COerficientofhorizontaleddy＼∫iscosity  

∇2：Laplacianoperatorror軌ehorizonは1direetion  

Table2 Pal・ameterSOftheexpcl・imcnts   

InclinELtion ofnorthel・IICOaStal  

Coeffientofhorizontaledd）・  

＼・iscositさ′（A一，）（incmニsecり  

VOOSE    VlOSE    V20SE    V30SE    VOOLE    VlOl．E    V20LE    V30LE  

5 ×10￠   

5 ×10￠   

5 ×10￠   

5 ×10     1×10†   

1×107    1×107    1×107   

0  0  0  0  0  0  0  0     1  2  n一リ      1  2  3  

28  

3．Results   

でheresulも0ぎVOOS王蚤withrelativ￠1ysmalleddyviscosity（Ah＝＝5×108cm2sec￣l）isshowninFig．2．An   anti−CyClonicandacycloniceddyare rormedin a northwestern area and a mean flo＼＼r Shows alarge  

meanderpattern．The cyclonic eddyis weakened and stretchedin south＼＼√ard direction．Later．this   CyCloniceddyiscut−Offfromthemeanflowanddecaysatabout55days．Ho＼＼▼e、・er．verySmallcyclonic  

arearemainsnearthenorthernboundaryandanewcycIoniceddyisgeneratedin eastern area．This  

CyCloniceddyshiftswestwardanddevelopsfurthermoreinthenorthwesternarea．Theflowpatternat  

carriedoutまn120〜125days．‡nlat紺time，Similarspin・upandspin−downarerepeat￠d（Fig．幻．  

Namcly，theformercorrespondstotheformatiQnOfcycloniceddyanddevelopmentofthecycloniceddy  

througheastwardshift，thelatteristhedecayofthecycioniceddyafteritscut・Offfromthemeanflow．  

lnordertoseethedetailsofthetimee＼・01ut・ionofthecycloniceddy．timechangeinthevolumetransport   OfthecycIonieeddyisshollrninFig．3a．ThespiJl−uPandspin−downofthecycloniceddyhasaperiods   Or70da〉′S．Small＼，ariationisdetectedaftertheoccurrenceofthespin−uPShownbytheabruptinerease  

＼ 丁手  

卜q  …、 −1851・3k・  −  Df  

桓ヨヰ掴臥8km  

還蜃丁⊥甘T⊥且  

丁⁚⁝⁝⁝・・芸・≡⁚⁚⁝ぎ⁝⁝⊥∵∴   油土痺甘−芦ぎ  

OUTFLOH  

Tヾ・・・≡宰旨 ⁝⁝∴・⊥  

ー顔1合桓訃187，Okn  

INFしOH  

Fig．1Schematic view of the numericalmodelwith four different northern coastal  

bound−aries．Twohatchedareawithclosedarrowsindicatetheboundarywithin−  

and   

Coastaltopographicefrectsonwesternboundarycurrent．Ⅰ   29  

Fig．2−1  

Fig．2 ResultsofVOOSEshownbythespatialdistributionofvolumetransportfunction．  

Thecontourintervaloftransportfunctionis20Sv andareaswithnegative＼・01ume  

transportfunctionarestippled．   

Yoshihiko S】ミKINEand Akiya Aso    30  

Fig．2−2  

31   

Coasは1もOpOgraphicerrectson、VeSternboundarycurrentlI  

32  

inthe、・Olumetransportortheeyclonicedd）・・．ThesecoL11・eSpOndtotheenhanccmentorthceさ・Clonicedd〉・  

（1uringthc＼VeStWardshiftandjustbeforethccut−OfffromthemeanrLo＼＼′．TheformercEISeisseeninthe   flowpa地rnsin380・390daysand580−590days，沈elatterin400−410daysand680・690days．   

でheresultofVOOLEwithrelaもiv￠1ylarg￠eddyviscosiもy（Ak＝107cm2sec山りisshowninFig．4．The  

Spln−uPandspin−downofthecycloniceddyarealsocarriedout．However，SOmedifferentpatternsfrom   VOOSEaredetected．Firstly，thereexisもsadecreaseirlthep8riodofthespirトupandspin−down：theぎirst   decayorthecyclo11iceddyoccursspin−upir140days，WhilethatinVOOSEoccursaも55days，Whiclliselear   inthetimechangeinthe＼，01umetranspol・tOrthee）・Clonicedd）▼Sho＼＼・ninFig．5a．Itisshown Lhat the   averagedperiodofthespln−uPandspin・downisabout50daysoverallthetimeinteg・ratedperiodoflOOO  

days，WhilethatofVOOSEis70days（Fig・、3a），Anotherdirrerenceisnoenhancementorthecyclonic   eddy，Whichisdetectedintheflowpatternof30−40days．Furthermore，CuレOffofthecycIoniceddyis   notcarrまedout．Thecycloniceddymonotonouslydecaysa鮎relonga鳥ngsouthward．Onもhewhol￠，it  

is delnOnSLl・atCd that alarge rl、ictionalefrcctin VOOLE enhances the decay of the c）・Clonic eddyin   COmParison＼＼・ith thatin VOOSE andit resultsin the short period of spin・uP and spin−do＼＼・n and n0   0CeurrmCeOrthespln−upand払ecut−0汀orthecyeloniceddy．  

3−2 Casesll・ithinclinednorthernboundary（8＝100）   

Thel・eSultofVlOSEwiththesmalleddyYiscosityisshowninFig．6．Acycloniceddyisformedand   its＼・OlumeLransportoseillatesarOundlOS、・（Fig．3b）．AftertlleSOuth＼Vard elongation ataboutllO   days，Cut−Ofriscal・riedoutin120−130daysandthecut−Ofreddydecaysin135days．Ho＼、，e＼・er，remaining   CyClonieeddy near the norther11boundarylS maintaまned and enhaneed agaln arter140days．でhis  

︵＞S︶−ヒOdSZ＜仁卜 ︵＞S︶ ↑UOdSZくUト︵＞S︶ ト∝OdSZく江ト  

a   ∩︶  ■U n︼  ︵U O  ▲U d  ﹂  つ﹂  

dOO  

DAYS  

b   ▲U  ︵U  ▲U ︵U O  β  ．〇  一月 ＋つー  

DAYS  

ニこ 

．二  

C   S  Y  A  n︶  

Fig．3 Timechangeinthevolumetransportoftheeyelonieeddy．（a）VOOSi王，（b）VlOS‡壬  

and（c）V20SE，   

33   

Coastaltopographic￠rfectsonwesもernboundarycurrent・Ⅰ   Fig．4−1  

Fig．4 SameasinFig．2，butぎorVOOLE．  

Yoshibiko SEK工NEand Akiya Aso   

34  

Fig．4−2  

Coasもaltopographicefrectsonwesもernboundarycurrent．Ⅰ   

35  

▲リ  ▲U n■  0  人U  ▲∪  一b ・ろ  3  ウー ・−   

てS︶ 卜∝OmSZく∝ト   

a   0 0  n■ ■U  ︻U  ■U  S   一   tlヽ  ■  ・−  

︵．の︶ ト∝OmSZV∝卜   

b   

ヰ00   800   eDO   1880  

ロAYS  

∩∨  八V  ハV O ∧U O O O  ︻U   8  り・ 8  S  ▲t  勺一 ケヽ −t  

︵︐S︶ 卜∝OdのZく広ト  

C  

0   200   400   880   800   10ロ8  

ロAY5  

Fig．5 Sameasまnyig・．3，butぞorthecaseswithlarg即eddyviseosity．（a）VOOSE，  

（b）VlOS‡王and（c）V20SE．  

CyCloniceddyiselongatedsouthwardat22Odaysanddecaysat245days．Thespln・upandspin−downof   the c〉・Clonic eddy al・e rePeated upto580daysIHo＼＼▼e、Ter，it should be noticed that the spin−up Of the  

C）・Clonicedd），doesnotoccurs after＼Vards andonlylarge anti−CyClonic circulationis formed．This   anti−eyeloniceirculationisstables and the straight flow along northern boundaryis maintained sta−  

tionary・Onthe、Vhole．itissuggestedthatthereexist t＼ヾO repreSe王Itati＼・e flo＼＼▼PatternSin this model．  

Oneisameandel・flo、、′Pattenandotheroneisastraightflowalongnorthernboundar）1．   

The results ofVlOLE＼ヾith thelarger cddy＼，iseosityis sho＼＼▼nin Fig．7．Although gro＼＼・th of the   CyCloniceddyisalmo＄もcommoJltOVlOSE∫the5pin−downoccursquiekly：theぎirstdecayorthecyclonまe  

edd）・OCCurSat about90days．＼＼・hile the deca）・in VlOSEoccurs atabout135days．Artel・this，almost   Similarspin−upandspin・do＼Vnarerepeated（Fig．5b）．Thus，thestraightmeanflowsho＼＼・nin VlOSE  

（F短．6）isnotrormedinthiscase，  

3−3 Casesll，itllinclinednorthernboundary（0＝200）   

ResultsorV20SEareshowninf ig．臥 Aeycloniceddyisformedinthe8aSternareaOどthenorthern   boundaryandiもdoes not show the westward shift．This cyclonic eddy decays at120days and a   dominantantま・CyCloniceirculationisgenera七色dinthec弧tralbasin．でheねtalflowpatternr￠Semblesto   thatofVlOSEまnthelaterperiod．Becauseofthesouthw￠S抽ardintrusionof血ecyclonまeeddy，mean   rlowseparatesrromthenorthernboundary．   

ResultsofV20LEareshol＼・ninFig．9．AlmostsimilarflowpatternstothoseotV2OSEarcfoundinthe   initialstage，ho、VeVer development of the two cyclonic eddiesis relatively slow．ln particular，  

SOuth＼＼▼eSt＼＼，ardintrusionofthec）・Cloniceddydoesnotoccurandtheseparationofthemeanflo＼＼一isnot   

36  

Fig．6−1  

Fig．6 SameasinFig・．2，butforVlOSE．   

37   

38   Yoshihiko S】；KINE and Alくiya Aso   

Fig．6−3  

Coasは1topog・rap】1icerfecもsonwesternbou】1darycurrent．Ⅰ   Fig．6血4   

Yoshihiko SEKINE and Akiya Aso  

40  

Fig．7−1  

Fig，7 Sameasin】γig・2，butrorVlOL軋   

41   

YoshiIlil柑SE‡く1NE and Akiya Aso  

Lt2 

Fig．8−1  

Fig．8 SameasinFig・2，butrorV20SE・   

CoastalとOpOg・raphまcerfectsonwesternboundarycurrent．王  

43   

Fig．8…2  

Yoshihiko SEKINE and Akiya Aso 

44  

Fig．9−1  

椚g．9 SameasinF痩．2，buもforV20LE・   

Coastaltopographiceffectsonwesternboundar）・Current．l  

45   

Fig．9−2  

Yosili最ko SE‡く1NEarld Akiya Aso  

yig．1O Sameasinyig・2，butrorV30S‡ミ・   

Coastaltop（唱ral〕王IicefrecもSOnWeSt甜nboundarycurr￠nt．Ⅰ    47  

carriedout．Although thereexistweaktime variationsin thecycloniceddyin north ofthe outfiow  

（yig．5c）andinthedominanもanti・CyClo11iccirculaもion shown by the contour of volume transport   runctまonlagertllan60Sv，tOtalflowpatternaもt扇nsstatiorlaryStateafter120days・  

3LICLLSCS＼1・itllinclinedl101・lhcrnhoulldatl）・（0＝30O）   

ResulとSOrV30SI；（yig．ユ0）ischaracterizedbynoformatiom ofthecycloniceddyin south to汰e   inclined王10rthernboundary．Incontrasttothis，CyClorlic eddyin north orthe mean ouげlow develops   S噌nificantly．Statknarystateisaもtainedatabouも60−70days，eXCeptrOrthewestwardpropagationsoで  

eddiesinasou抽ernareaorもhemodelbaぶまれ．88CauSeOfti18ぎ0上、m汲もionofユargearld如ror将allti−CyCユoJlic  

flow，SOuth・WeSじWa王、ddev￠lopmentofthecyclonicflowissuppressed．Totally，mean rlow shows a   sもrongじendencytoぎlowalong・nOr払ernboundary．．Thist紺dencylS alsoroundintherlow patternor   V30LE（Fig．11）．However，developmentorthecycloniceddyis＼㌢ery Weakin comparisonwith V30   S軋 Never軌￠1ess，relativelylargevolume transportofthecycloniceddy north or軌8m8an rlowis  

detectedinaninitialstage．Toseethedetailsofthevariationinthecycloniceddyinnorthofthemean  

rlow，timechangeinthevolumetransportorthecyclononic￠ddyisshowninFig・．12．ÅsrorV30SE，Very  

largevolumetransportwithirregulartimeehangearound210Svisdetected，Whileclearoscillationorthe  

volulnetranSpOrもis roundin V30L王ミ，arter tbe spln−upinもheinitialperiod．Because or the small  

rrictionaldumplng・irlV30SE，iもisまndicated thatenhancodcyclonicandanti−CyClonic circulation8．re   formedbythetotalkineticenergybalanc80rthein−andoutrlowsyst￠m．  

一1．Su111111こ11T  

Thewesternboundal、ycurrentflowlngalonganzonallyaslantcoastisexaminedwithspeciairere王、ence   もOthedegreeorthecoastallineinelillationrromzonaldirectionattheeastwardflowlr喝pOrもion．Åsthe  

prelimirlary Study，basic numericalsoluもions have been presented．Main results or the numorical  

solutiollSareSummarizedasfollows：  

（1）‡もitshownrromthetotalreaturesorthenumericalexperimentsthaもtber8eXisもtwo r8preSerltative    flowpattern：OneisamendQrrlowpattern and the otheris a straightrlow pattQrrlalor慣nOr血ern   

boundary．In case of the meander rlo＼V pattern，Spln−up alld spin−down oど払￠ eyClonic eddy   

（2）Meande王・fまow paとたeエ■nis fornledinとhe cases of zona】nortき1eエー幻bound∂ry．Tileぶpまかup and   

spln−downorthocyclorliceddyaccompaniedbythemeanderpathoecurswま班aperiod or70daysin    smallQddyvisco＄iとy（Ahニ5×106cm2sec￣1）and50daysinlargei・eddyvまscos擁（A‡l＝107cmヱsec−り．  

（3）ChaoticchangerrommQanderrlowpatterntostraigh川owpaもternoccursatabout600daysin the    case＼710SEwiththeinclinaもionornorthernboundary oデ100andsmalledd〉r17iscosiもy．Straighも   

moanflow along northern boundarylS rOrmedin the cases with theinclination or the northern    boundarylargertllan200．  

Å11theaboveresultsalmostagl eeWiththoseorSekine王2）．However，itisshow11thaもthecyclonic   

￠ddyformedinnoユ†班ofthemeanoutflowhasainrluenceontheflowpattern．Thまscycloniceddyis   

notrormedinSekine−2），inwhichmeridionalcoastalboundarylntheoutflowareawasnotmodeled．   

BecatlSeSuCha meridionalcoastaltopographyiscく）mmOn tO therepr￠Senもaもive western boundary   

48   Yoshihiko SBKINE and Akiya Aso  

Fig．11SameasinFig・．2．butforV30LE．   

Coastaltopogl・aphiceffeetson＼＼reSternboundarycurrent・Ⅰ  

49  

0 0 0 0 0 0 0 0 8 0 8 d ヰ 2 0 8 d ヰ ー   

︵＞S︶ ト∝OdSZ＜∝卜   

DAYS  

︷U 八U O O・n︶ ︵リ 0 0 8   ∧0  ︼7  6  S  ヰ  蝕﹂− ○ん  ▲l  

︵＞∽︶ ト∝Om∽Nく∝ト b  

DAY5  

Fig・12 Timechangeinthe、・Olumetransportoftheeycloniceddyinnorthernsideofthe   meanflowintheoutflo＼＼rarea．（a）V30SEand（b）V30LE．  

currenも：eaSt訂nareaOfJapanfor払eKuroshioandnortherncoasは1topographyrromCapeHaももeras  

forLheGulf−StreaIn．Onthebasisoftheseresults，tOpOgraphicerrectofpeninsula＼＼，illbeexaminedin  

lhenextstepofthisstudy．  

AcknoIVledgment：TheauthorswishtoexpresstheirheartfeltthankstoProf．Y．Nagatafol・his、・aluable   commentonthefirstmanuscript・ThenulnericalcalculationswerecarriedoutonaVP−26000fNagoya   UniversityandonaFACOMM−7600fMieUniversity．Thisstudy＼VaSSupPOrtedbyaGraindinAidfor   ScientificResearchfromtheMinistryofEdueaもion，ScienceofCulhばeOfJapan（05640475）．  

Referenees   

l）Taft，B．A．Characteristicsoftheflowofthe Kuroshio south orJapan．In：l（uroshio−Its physical    aspecもS，H．StommelandK．Yoshida，editors，Univ，Tokyopress，pp．165−214（1972）．  

2）Nitanま，H．VariationortheXurosiliosouthorJapan．J．Oceanogr．Soc．Japan，31，154−173（1975）．  

3）Ishii，H．．Y．SekineandY．Toba．Hydrographicstructure of theIくuroshiolarge meander−COld    watermassregiondowntothedeeperlayersoftheocean．］．Oceanogr．Soc．Japan，39，240−250   

50  

（1983）．  

4）Robinson，A．TheGuまfSもr8am，Pbま1．でrans．R．Soご．Lond−Aり27￠，351−370（197ユ）．  

5）White，W．B．andJ．P．McCreary，TheKuroshiomeanderanditsrelationshiptothelarge・SCaleocean   

6）Chao，S・Y．andJ．P．h：・1cCreary．A numericalstudy or thcIくuroshio south ofJapan．］．Ph）・S．   

Oc￠anOgrり12，680逓93（1982）．  

7）Masuda．A．Aninterpretation ofthe bimodcIcharacter ofthe stableIくul、oshio path．Deep−SeEI   

8）Yasuda，I．］．H．Yoon and N．Suginohara．Dynamicsofthel（uroshiolaIlgle meander−barotropic    model．］．Oceanogr．Soc．Japan，41．259−273（1985）．  

9）Chao，S−Y．BimodaliもyortheKuroshio．J．Phys．Oe母anOgrり14，92・103（1984）．  

10〉Yam咽ata，T．andS．Umatani．Geomeもryイorc◎dcoberenも如ructureasamodelorth￠Kuroshiola柑e   

11）Yoon，J．H．andI、Yasuda．Dynamic＄Ort‡1eKuroshiolargem組nder．Two・1ayermodel．J．Phys．   

Oceanogr．，17．66・飢（1987）．  

12）Sekine，T．CoastalandbottomtopogTaphiceffectson thepa亡h dynamics orthe westel・n boしIndary    CurrentWithspeeialreferencetotheIくuroshiosouthofJapan．Lamer，26，99−1小1（1988）．  

13）Sekine，Y．A numericalexperimenton thepath dynamics ortheIくul・OShio＼ヾith refercnee tolhe    formationofthelargemeandel・PathsouthofJapan．Deep−SeaRes．，37．359−380（1990）．  

14）Akitomo，K．，T．AwajiandN．Imasato．Kuroshio path variation south ofJapan．1Barotropic    inrlow−Outrlowmodel．J．G￠Ophy凱Resリ粥，2549・2560（1991）．  

西岸境界流に及ぼす陸岸地形効果   第1部 陸岸地形の東西からの傾きの影響  

関根 義彦・麻生 晃也  

三盛大学生物資源学部  

要旨：腰圧数億モデルを用いて西岸境界流に及ぼす陵塵地形効果に関して，特に東西方向からの北側陵辟境界の傾斜   の影轡を調べた。この論文では得られた結果の詳細な流れのパターンを提示した。数値モデル実験により，蛇行する   流れのパターンと辟に沿う直選する流れのパターンの二つの代表的なパターンがあることが示された。蛇行する流れ   のパターンの場合には，蛇行する一般流に伴い低気圧渦が生じ，強化と減資を繰り返す。蛇行パターンは北側の境界   が東西の場合に生じる。カオス的な蛇行パターンから直進パターンへの変化が100の栄西方向からの傾斜と相対的   に小さい渦粘性係数を与えたモデルで発生した。直進する一般流は東西方向からの傾斜が大きい場合に発生する傾向  

が見られた。