numerical simulation of the transient response of the kuroshio leading to the large meander formation south of japan using a three dimensional primitive equation numerical model that takes realistic topography into account we successfully reproduce the observed transient response of the kuroshio south of japan during the transition from the nonlarge meander path to the large meander path the transient response is triggered by the generation of what is called the trigger meander off the southeastern coast of kyushu resulting from the supply of cyclonic vorticity through vertical stretching caused by the interaction between the kuroshio and the anticyclonic mesoscale eddy approaching the tokara strait the trigger meander thus generated propagates eastward south of shikoku while inducing an anticyclone cyclone pair in the lower ocean after the trigger meander passes cape shiono misaki it slows down and rapidly amplifies so that the kuroshio loops back west of the izu ogasawara ridge then the sharpness of the meander trough gradually relaxes and the large meander path is attained during the rapid amplification of the trigger meander off cape shiono misaki the abyssal anticyclone develops while being trapped by the local topographic feature koshu seamount located 200 km to the south of cape shiono misaki this abyssal anticyclone plays a crucial role in intensifying the trigger meander trough in the upper ocean via cross frontal advection the intensified trigger meander trough then further amplifies the abyssal anticyclone over koshu seamount this joint evolution of the upper ocean meander trough and the abyssal anticyclone suggests that baroclinic instability enhanced by koshu seamount is the dominant mechanism for the rapid amplification of the trigger meander leading to the large meander formation south of japan

interannual variability of the kuroshio transport in response to the wind stress field over the north pacific its relation to the path variation south of japan we have investigated the interannual variability in the kuroshio transport focusing on the baroclinic response of the upper ocean to the long term variation of the wind stress field over the north pacific from 1961 to 1987 first temporal change of the kuroshio transport at the western boundary from 17 to 31 n has been estimated on the assumptions that the kuroshio is a baroclinic flow confined in the upper layer and that the effect of interior wind stress curl on the volume transport at the western boundary is transferred by nondispersive baroclinic rossby wave peak values in the estimated transport appear in its beginning region 17 21 n when or just before the kuroshio settles into a meandering state south of japan in 1975 1981 and 1986 these peaks are due to negative wind stress curl anomalies which are induced by the intensified trade winds in the central and eastern tropical north pacific on and just after an el nino event and in the western tropical north pacific months to years before the next el nino event such peaks are not found in the barotropic sverdrup transport in downstream regions i e in the east china sea and south of japan north of 23 n on the contrary the estimated transports through baroclinic and barotropic responses do not have such good correlation to the path variation temporal change in thermocline depths estimated from bathythermograph data clearly shows the westward propagations of positive anomalies by nondispersive baroclinic rossby waves at latitudes of the beginning of the kuroshio south of 21 n which is in phase with peaks of the kuroshio baroclinic transport at the western boundary on the other hand there are only the local propagations of the anomalies in the downstream regions as previous studies reported however it is emphasized that temporal change of the geostrophic transport in the east china sea 28 n is coincident with that of the baroclinic transport at the beginning of the kuroshio not with that at the same latitude a numerical experiment with a nonlinear reduced gravity model confirms that temporal changes of the transport in the east china sea and south of japan are due to the advective nonlinear effect of the kuroshio itself while the linear baroclinic response to the wind stress field is dominant in its beginning region

effects of stretching on maintaining the kuroshio meander 1 using a two way nested grid ocean general circulation model driven by a repeat annual cycle forcing the kuroshio path variation is examined by varying the strength of wind forcing for climatological or 10 weaker wind forcing both large meander lm and non large meander nlm paths alternately appear with each type of path continuing for a few years to a decade this timescale and path transition processes are generally consistent with observations for the lm path the main balance in the depth integrated vorticity equation for the upper ocean is shown to be between the beta advection and stretching terms the stretching term is comparable to and has the same sign as the beta term at the western side of the meandering part indicating that the stretching term has the effects of shortening the wavelength and stabilizing the lm path the stretching term is mainly determined by downwelling caused by crossing of the upper and deep flows contrary to the above two cases only the nlm path appears for 10 stronger wind forcing it is suggested that the strength of climatological wind forcing is near the upper limit that allows the lm path to occur in this study the control experiment is carried out by choosing parameterizations and parameter values to reproduce the kuroshio path variation as realistic as possible therefore the results from the two sensitivity experiments are expected to represent a realistic response of the kuroshio path variation

geometry forced coherent structures as a model of the kuroshio large meander abstract the bimodality of the kuroshio path south of japan is presented from a new viewpoint of direct interaction of current with local coastal geometry by solving the barotropic quasi geostrophic equation in a channel with steplike coastal geometry we demonstrate that the model kuroshio can actually show the localized bimodal behavior for a reasonable range of inlet current speed the amplitude of the large meander is approximately given by 2umax in contrast to all nonlocal model results our local coherent structures have nothing to do with the basin size geometry such as kyushu and the izu ogasawara ridge in general the present study suggests that even a small feature of coastline geometry may trigger a big change in a nearshore current

formation process of the kuroshio large meander in 2004 1 formation process of the 2004 kuroshio large meander has been examined using a data assimilation and prediction system the small meander southeast of kyushu that occurred in december 2003 remains stationary until the next spring the vorticity analysis indicates that this small meander is maintained by a balance between the advection and the bottom pressure torque on the continental slope this balance is achieved as a result of reducing the advection by a westward propagating negative temperature anomaly originating in the wind stress field the small meander starts moving eastward around may 2004 when an anticyclonic eddy east of the tokara strait is intensified by coalescing of two anticyclonic eddies at that time a deep anticyclonic eddy is generated below the kuroshio by a cross frontal flow the deep anticyclonic eddy grows up during its eastward propagation then a southward flow in the eastern part of the eddy carries the kuroshio path offshore bringing about the large meander the eddy energetic analysis indicates that baroclinic instability is essentially responsible for this large meander formation the sensitivity analysis reveals that the small meander and the intensified anticyclonic eddy significantly affect the phase speed and the amplitude of the meander respectively it is also revealed that a slow phase speed and a large amplitude of the meander are regarded as conditions for the stationary large meander which is also applicable to the past large meanders in the 2004 large meander these conditions coexist by the stationary small meander staying until the intensified anticyclonic eddy triggers baroclinic instability

a review of numerical ocean modeling 1983 1986 midlatitude mesoscale and gyre scale for the years 1983 to the present numerical modeling of midlatitude ocean circulation on the mesoscale and gyre scale is reviewed numerical results have shown great similarity to recent thermocline theories but also some important differences in particular ventilation of the pool zone caused by convective processes is substantial also solutions employing explicitly resolved eddies differ significantly from their equilibrium counterparts inverse methods have provided improved estimates of meridional heat transport and tropical upwelling of tracers the crucial influence of the western boundary on the circulation of the gyre interior is beginning to be understood research has focused on the conditions for radiation by jets the relationship between a jet s structure and its stability and the generation of deep mean flows by eddy activity near the surface constraints on the structure of isolated vortices imposed by instability mechanisms have been explored with new balanced models which provide an inexpensive but accurate alternative to primitive equation models for many oceanic processes transport of salinity by gulf stream rings has been found to be comparable to the effects of evaporation and precipitation in the slope water it has also been shown that radial circulation in warm core rings cannot be disregarded as a possible cause of ring spin down in anticipation of a dramatic increase in the oceanic observational data base from altimetry scatterometry tomography and in situ measurement new modeling techniques for data assimilation and prediction are beginning to be developed

stable paths of the kuroshio south of japan determined by the wind stress field 1 to investigate the role of the wind stress field in determining stable paths of the kuroshio south of japan we have executed numerical experiments with a two layer wind driven ocean model changing zonal and meridional wind stress distributions four types of path two straight and two meandering paths have been found and their appearance has been classified into three categories in category i straight and meandering paths coexist multiple equilibrium only a meandering straight path appears in category ii iii a meandering path tends to appear when the sverdrup transport along the southern coast of japan decreases downstream strongly and the wind stress curl is anomalously negative in the western region near japan whereas a straight path is apt to occur with the positive anomaly detailed examination of the results has revealed the following mechanism determining stable paths of the kuroshio the wind stress field first determines the pressure difference p between the two ends of the southern coast of japan when p is smaller than a certain threshold only a meandering path can exist since the along coast pressure decrease in a straight path state is much larger than p category ii conversely when p is larger than another threshold only a straight path is consistent with the larger p category iii both paths can appear when p is between the two thresholds category i the climatological wind stress field in the north pacific subtropical region has been suggested to be in category i

minturn circles a new glacial feature in inglefield land northwest greenland a new glacial feature has been found consisting of well defined circles and rings ranging in size from a few metres to about 80 m in diameter and in colour from black to pink more than 300 circles and rings are known they are composed of slightly rounded boulders cobbles and pebbles frequently overgrown with black lichen the circles and rings consist of syenite that was picked up by the inland ice under permafrost conditions by a melting refreezing process the syenite till was subsequently transported by the inland ice across ingiefield land and deposited in cut off meanders of melt water streams on the surface of the stagnant ice cap during melting of the inland ice the circles and rings were deposited on a peneplain consisting of boulder fields and outcrops of precambrian and cambrian rocks these circles are probably quite common features in high arctic regions but their recognition requires special conditions

interannual variability of the kuroshio onshore intrusion along the east china sea shelf break effect of the kuroshio volume transport the interannual variability of the kuroshio onshore intrusion koi across the east china sea ecs shelf break and its response to the ecs kuroshio volume transport kvt during 1993 approximate to 2010 are studied based on a high resolution real time and global ocean general circulation model since variability of kvt is mainly determined in the interior pacific it is rather a remote than a local factor for the local ecs koi on interannual time scales kvt affects koi not only in the net volume transport across the entire shelf break but also in the spatial pattern along the shelf break when kvt increases the intrusion decreases increases upstream downstream of the major intrusion region northeast of taiwan the retreating increases decreases upstream downstream of the main veering region southwest of kyushu these patterns are caused by cyclonic eddies induced by the seaward deflection of the kuroshio axis from the shelf break which ultimately results from the kvt increase a diagnostic mechanism of koi approximate to msin delta h 1 is proposed where h is the bottom depth is the angle between isobaths and the vertically averaged current and m is the absolute volume transport at the shelf break is large in the major intrusion retreating regions and stable on interannual time scales while m changes with opposite signs between upstream and downstream of the major intrusion retreating regions the mechanism explains well the relation of local kvt and the spatial pattern of koi along the shelf break in both the mean state and the interannual variations

new perspectives on the generation and maintenance of the kuroshio large meander abstractthe internal dynamical processes underlying the kuroshio large meander are investigated using a recently developed analysis tool multiscale window transform mwt and the mwt based canoni

the nonlinear optimal triggering perturbation of the kuroshio large meander and its evolution in a regional ocean model abstractbased on the regional ocean modeling system roms and the conditional nonlinear optimal perturbation cnop method we explore the nonlinear optimal triggering perturbation of the kuroshio

data assimilation in the low noise regime with application to the kuroshio abstractonline data assimilation techniques such as ensemble kalman filters and particle filters lose accuracy dramatically when presented with an unlikely observation such an observation may be caused by an unusually large measurement error or reflect a rare fluctuation in the dynamics of the system over a long enough span of time it becomes likely that one or several of these events will occur often they are signatures of the most interesting features of the underlying system and their prediction becomes the primary focus of the data assimilation procedure the kuroshio or black current that runs along the eastern coast of japan is an example of such a system it undergoes infrequent but dramatic changes of state between a small meander during which the current remains close to the coast of japan and a large meander during which it bulges away from the coast because of the important role that the kuroshio plays in distributing heat and salinity in the surrounding region prediction of these transit

bimodality of the kuroshio abstract a barotropic ocean model is used to study the bimodal behavior of the kuroshio to the south of japan by considering the combined effects of the beta plane the kyushu coastal perturbation the izu ridge and the sw ne tilted coastline the two frequently observed meander patterns have been numerically verified as the two quasi steady solutions contained n the model the small meander state is identified as an upstream disturbance largely forced by the izu ridge its width decreases as the strength of the current increases the large meander state is forced by the presence of both the kyushu wedge and the izu ridge topography for small volume transports the large meander state behaves like the small meander state in that the meander width decreases as the current speed increases for large volume transports it behaves like a lee rossby wave in that the width of the meander increases as the current speed increases the birth of the large meander state occurs as a consequence of the ocean spin do

kuroshio path variation south of japan 1 barotropic inflow outflow model we examined the dynamics of the variation in the path of the kuroshio current along the south coast of japan by use of a barotropic inflow outflow ocean model the model basin has an inclined coastline and includes a part of the east china sea so that we could investigate the effect of kyushu on the kuroshio we obtained three regimes of the kuroshio s path variation according to the magnitude of its inlet velocity vmax similar to the previous study the kuroshio takes a straight path along the south coast of japan in regime i with a low vmax a meandering path in regime ii with a high vmax and both of these paths multiple equilibrium state in regime iii with an intermediate vmax the transition from the straight state to the meandering state occurs with an increase in vmax from regime i iii to ii preceded by an eastward progression of a small meander which is produced as a separated vortex by the nonlinear effect of the flow and the effect of kyushu it takes 120 days consistent with observations the nonlinearity of the flow has two effects in the transition one causes a downstream shift of the small meander and the other enlarges it by pulling out positive vorticity from the no slip coast with an increase in the meander scale due to the latter effect the former effect becomes small to be balanced with the beta effect causing an upstream shift of the meander thus a large meander path is formed a small meander does not progress eastward to develop into a large meander until vmax exceeds a critical value this behavior causes a multiple equilibrium state in regime iii and only the meandering path in regime ii

low frequency variability in regions of the kuroshio extension and the gulf stream using sea surface height data collected by the topex poseidon altimeter we studied the low frequency variability in the kuroshio extension and gulf stream the most significant signals are the basin wide background seasonal cycle and low frequency wave activity generated over major bottom bathymetry and subsequent westward propagation in both regions the spatial structures of the seasonal cycle in the two regions are quite different in the kuroshio extension the seasonal cycle has a northeast southwest orientation and lies closer to the western boundary whereas it has an east west orientation and lies more offshore in the gulf stream the close relationship between the low frequency wave activity and major bottom bathymetry features is discussed through both empirical orthogonal functional eof analysis and calculation of eddy kinetic energy and reynolds stress the spatial structures of these eddy statistics are fundamentally different from those of high frequency mesoscale variability they are not in the proximity of maximum time mean flow but rather they lie mostly to the west of major bottom bathymetry the close association of the clusters of local maximum eddy properties with major bottom topographic features in both regions wave generation over the major bottom topographic features and subsequent westward propagation and difference of the eddy statistics from that associated with high frequency mesoscale variability all suggest that unlike in the case with high frequency mesoscale variability generation in which internal dynamics of the background mean flow such as nonlinear instability plays a fundamental role external forcing through bottom topography must play a fundamental role in generating the low frequency wave activity

an unusual stone circle chilcotin range british columbia canada a unique circular feature of uncertain origin lies above the tree line on the eastern flanks of the coast range of british columbia canada it is composed of white fractured angular cobbles to boulders predominantly under 1 m across arrayed in a slightly flattened circle nearly 50 m in diameter with the ring mostly about 4 m in width the felsic granitoid lithology of the circle is unlike any in the immediate region and no clasts of this composition occur within the circle the debris rests on soliflucted soil containing rounded pebbles to cobbles of granodiorite that forms the regional lithology the age of the circle is deglacial with post glacial modification given the absence of similar lithologic units in the region and no obvious symbolic purpose for such a feature an anthropogenic origin for the circle is improbable mechanisms for transporting the foreign rock unit to its final location distributing fragments into a circle and preserving it include flow of alpine and fringing continental

a comparison of surface eddy kinetic energy and reynolds stresses in the gulf stream and the kuroshio current systems from merged topex poseidon and ers 1 2 altimetric data analyses of surface eddy kinetic energy eke inferred from 5 years of merged topex poseidon and ers 1 2 altimetric data are presented in the gulf stream gs and the kuroshio ks current systems focusing on anisotropy and eke seasonal interannual and long term variations as well as reynolds stresses for both gs and ks a descriptive analysis of the eke field shows that it is anisotropic along the path of the currents and assesses the close relationship between the spatial distribution of eke high levels and bottom topography a striking ocean feature is found in the gs shaped as a zonal double blade structure in the eke field centered at 37 n 71 5 w that likely corresponds to a regular and permanent lateral displacement of the mean path of the current at this geographical location maps of eke seasonal means for years 1993 1996 and 1997 provide a detailed description of the surface variability meanders pinched off eddies etc and show strong interannual variations in the ks eke monthly mean changes in the ks reveal a well marked seasonal cycle during the first 3 years 1993 1995 with eke peaking in july august this is followed by a constant increase of its level from the beginning of year 1996 till the beginning of 1997 during this increase the zonal velocity variance u 2 is up to 30 higher than its meridional counterpart suggesting a zonal acceleration of the eastward flow eke seasonal changes are also found in the ks current 30 35 n 130 140 e and also show a regular annual cycle during the first 3 years which precedes by 2 months the eke seasonal cycle in the ks extension maximum in may june the maximum in eke in both regions precedes by 2 months the maximum surface transport found by qiu et al 1991 and zlotnicki 1991 occurring in july and late september respectively no such annual cycle is found in the gs region during the first 3 years year 1996 is anomalous in both current systems with mean eke level that increases by more than 20 compared to the other years also eke monthly mean changes in the ks reveal a well marked positive tendency in the eastern part of the current of more than 300 cm2 s 2 yr 1 and a negative tendency both in its eastern part and in the ks current this feature is absent from the gs at last eddy mean flow interaction is presented both the spatial averaging of turbulent quantities and the relative contribution of the different terms of the horizontal momentum fluxes are discussed a tentative explanation is given for the anomalously large u 2 at the end of 1996 in the ks extension

contourites in the fram strait abstract multichannel seismic reflection profiles from the fram strait show many features that can be attributed to bottom current influence on the sediments by comparison with well known contourite sequences elsewhere a greater than 2 km thick contourite drift with a smooth internal reflection pattern is observed northwest of svalbard the currents here have probably been controlled by local topography we interpret sequences with abundant diffractions in the broader basins to be current related probably deposited during periods of intensified circulation the continental slopes on the svalbard side have fairly continuous sequences whereas the younger sequences on the greenland lower slope onlaps the lowermost one this can be attributed to differences in current regime sediment supply or margin subsidence the contourites of the lower slope in the northeastern part of the strait about 1000 m water depth can be explained by long term influence of the west spitsbergen current but current influenced patterns down to 3000 m water depth are not compatible with the weak deep water circulation observed at present the oldest contourites west of svalbard are estimated to be of late miocene to pliocene age between 10 and 3 ma based on correlation to the dsdp site 344 and inferred basement ages near the present plate boundary hiatuses may be present beneath the contourites the onset of currents may be related to opening of the gateway between greenland and svalbard to climatic cooling and to palaeogeographic changes outside the fram strait contourite deposition has continued through the late neogene and quaternary but vertical changes in the pattern suggest that current intensities have decreased through time

two different aperiodic phases of wind driven ocean circulation in a double gyre two layer shallow water model abstract a two layer shallow water model is used to investigate the transition of wind driven double gyre circulation from laminar flow to turbulence as the reynolds number re is systematically increased two distinctly different phases of turbulent double gyre patterns and energy trajectories are exhibited before and after at re 95 deterministic and fully developed turbulent circulations in the former phase the inertial subgyres vary between an asymmetric solution and an antisymmetric solution and the double gyre circulations reach the aperiodic solution mainly due to their barotropic instability an integrated kinetic energy in the lower layer is slight and the generated mesoscale eddies are confined in the upper layer the power spectrum of energies integrated over the whole domain at re 70 has peaks at the interannual periods 4 7 yr and the interdecadal period 10 20 yr the loops of the attractors take on one cycle at those periods and display the blue sky catastrophe at re 95 the dou

gulf stream bimodality and variability downstream of the charleston bump gulf stream mean flow and variability have been studied in the gulf stream deflection and meander energetics experiment damex this study was conducted between september 1981 and april 1982 in the area of the charleston bump off the coast of the southeastern united states using data from an array of current meters and satellite imagery it has been shown that the seaward deflection of the gulf stream by the bump has a bimodal character and that the gulf stream meander field downstream of the bump differs between the two states of deflection the two deflection conditions have been termed the weakly deflected state and the strongly deflected state in this paper a weakly deflected gulf stream flows past the charleston bump and close enough to the edge of the continental shelf that its shoreward sea surface temperature sst front remains inshore of the 600 m isobath between charleston and cape hatteras a strongly deflected gulf stream turns sharply eastward at the bump and flows seaward far enough to have its shoreward sst front offshore of the 600 m isobath for several tens of kilometers along the continental slope downstream of the bump the transitions between deflection states may occur very rapidly and once in a strongly deflected state the gulf stream may remain so for up to several months two transitions were observed during damex one from a weakly to a strongly deflected state and one in the other direction the transition from weakly to strongly deflected state took only a few days at a given site while the signatures of the other transition were not as definite in the data records the strongly deflected state occurred during the fall and winter in damex october through january and satellite observations from earlier years suggest that it is this time of year in which the strongly deflected state preferentially occurs it was not clear from the damex data alone how the transition from a weakly deflected to a strongly deflected state may be induced but path or transport changes in the gulf stream as it approaches the bump and interactions between the current and rings or eddies are candidate mechanisms the bimodal character of the stream s path affects the low frequency variability of the current between the charleston bump and cape hatteras in the following manner typical meander frontal eddy patterns dominate the mesoscale fluctuation field during times of weak deflection while larger amplitude meanders of the gulf stream jet which can have very sharp curvature and strong anticyclonic circulations in their crests exist during times of strong deflection furthermore these larger amplitude meanders which we call the damex biweekly meanders have generally slower phase propagation speeds than do the typical meander frontal eddy events about 20 25 km day compared with 35 60 km day as well as longer periods about 16 days compared to 1 week

stochastic dynamics of sea surface height variability sea surface height anomalies measured by the ocean topography experiment topex poseidon satellite altimeter indicate high values of skewness and kurtosis except in a few regions including the gulf stream the kuroshio extension and the agulhas retroflection that display bimodal patterns of sea surface height variability kurtosis is uniformly greater than 1 5 times the squared skewness minus an adjustment constant this relationship differs substantially from what standard gaussian or double exponential noise would produce however it can be explained by a simple theory in which the noise is assumed to be multiplicative meaning that a larger background state implies larger random noise elements the existence of multiplicative noise can be anticipated from the equations of motion if ocean dynamics are split into a slowly decorrelating deterministic component and a rapidly decorrelating contribution that is approximated as noise such a model raises the possibility of predicting the probabilities of extreme sea surface height anomalies from first physical principles and may provide a useful null hypothesis for non gaussian sea surface height variability

effects of stratification and bottom topography on the kuroshio path variation south of japan part ii path transitions in a multiple equilibrium regime abstract the effects of stratification and bottom topography on the kuroshio path transitions in a multiple equilibrium regime due to a short term velocity increase are examined using a two layer inflow outflow model with simplified coastal geometry and bottom topography for an imposed velocity increase on a straight path state the typical transition from a straight to a meandering path occurs with or without bottom topography through the same process as in a barotropic case with flat bottom thus the geometrical effect of kyushu is essential to this transition or to the formation of a small meander triggering the transition stratification and bottom topography are somewhat secondary nevertheless under the influence of stratification a small meander significantly develops south of kyushu during a decreasing phase of velocity through shoaling of the interface depth and triggers the transition with the amplification rate of velocity amp of 1 5 the continental slope south of japan prevents a small me

the impact of ocean surface currents on sverdrup transport in the midlatitude north pacific via the wind stress formulation abstracta more complete wind stress n formulation takes into account the ocean surface currents vo while the conventional wind stress c popularly used in ocean circulation models is only a function of 10 m winds v10 an analytical solution is derived for the difference of sverdrup transport induced by using n instead of c a scaling analysis of the analytical solution indicates a 6 reduction of the sverdrup transport in the north pacific i e the kuroshio transport in the east china sea when ekman velocity dominates the ocean surface currents because of the quadratic nature of wind stress four nonlinear terms contribute equally to this difference two vorticity torque terms and two speed gradient torque terms a pair of 12 5 yr july 2002 14 hybrid coordinate ocean model simulations that only differ in the wind stress formulation are used to test the analytical solution the model results 2004 14 confirm that using n instead of c reduces the sverdrup transport in the north pacific by 8 17

effects of stratification and bottom topography on the kuroshio path variation south of japan part i dependence of the path selection on velocity abstract numerical experiments are executed using a two layer inflow outflow ocean model with simplified geometry to investigate the effects of stratification and bottom topography on the path variation of the kuroshio south of japan in a flat bottom ocean the dependence of the kuroshio path selection on its inflow velocity vmax is basically the same as in a barotropic ocean that is the kuroshio takes a straight path at low vmax regime i a meandering path at high vmax regime ii and both paths at intermediate vmax regime iii multiple equilibrium state however the range of regime iii shifts to higher vmax by 0 10 0 30 m s 1 stratification causes and maintains the offshore shift of the current path south of kyushu through the conservation of potential vorticity as a result a small meander stagnates southeast of kyushu not developing into a large meander even for higher vmax since the vorticity supply from the coast is reduced for the same reason higher vmax is needed to maintain a meande