south china sea isopycnal surface circulation this paper investigates the seasonal variabilities of the south china sea isopycnal surface circulations and of the kuroshio intrusion through the luzon strait using the u s navy s climatological temperature and salinity dataset public domain with 83 8 resolution by the p vector method the representative pattern is a persistent basin scale cyclonic circulation away from the surface and a seasonally varying circulation with a weak anticylonic gyre in the summer and a strong cyclonic gyre in the winter near the surface this pattern is consistent with a classical view of mean cyclonic circulation in large stratified lakes and semienclosed marginal seas by emery and csanady and with a recent numerical simulation using the navy s layered ocean model by metzger and hurlburt the computed monthly volume transport through the luzon strait is negative inflow all year round with a minimum value of 213 7 sv in february strongest intrusion and a maximum value of 21 4 sv in september weakest intrusion the annual mean transport is 26 5 sv intrusion

effects of groundwater level on seismic response of soil foundation systems abstracta set of dynamic centrifuge experiments was performed to assess the effect of the depth of the groundwater table on the seismic site response and kinematic interaction of a foundation on un

multidecadal oceanographic changes in the western pacific detected through high resolution bomb derived radiocarbon measurements on corals high resolution measurements of radiocarbon 14c in corals can be used to reconstruct past variability in ocean conditions here we report seasonal 14c changes in coral from ishigaki island japan and compare with previously reported data from palau and guam our data clearly indicate a significant increase in 14c from 1947 to 1998 related to atmospheric nuclear bomb testing the three early 14c spikes related to the atmospheric nuclear bomb tests in the us proving grounds at bikini and enewerak atoll conducted in 1954 1956 and 1958 were detected from the ishigaki coral after 1976 variability in the mindanao dome region related to north equatorial current nec bifurcation latitude migration affected the 14c difference between palau and guam whereas the difference between ishigaki and guam was not correlated with the bifurcation latitude the 14c difference between ishigaki and guam may be due to mesoscale eddies in the kuroshio area on the decadal scale the northward shift of nec bifurcation latitude after 1976 the year as known as pacific decadal oscillation regime shift from negative to positive was concurrent with the abundant westward propagating mesoscale eddies in the subtropical countercurrent region and stronger kuroshio transport off the east taiwan which may be represented by a smaller 14c difference between ishigaki and guam after 1976

kinematics of the philippine sea plate in this study new instantaneous rotation vectors describing the motion of the philippine sea plate relative to surrounding plates are determined that most nearly satisfy all available geological geophysical and seismological observations along the plate margins pacific philippine and caroline pacific poles are generated from a set of trial eurasia philippine poles of rotation using published determinations of the eurasia pacific and caroline philippine poles the pacific philippine caroline pacific and eurasia philippine poles are then checked for agreement with 1 slip vectors determined from focal mechanisms of earthquakes along the ryukyu trench and the nankai trough 2 convergence at the sagami trough 3 extension in the mariana trough 4 extension behind the bonin trench 5 extension in the western sorol trough and 6 convergence at the mussau trench trial eurasia philippine poles are eliminated if predicted plate motions do not match observed plate motions the locations and rotation rates of the three best fitting poles are eurasia philippine 37 0 n 141 0 e 1 60 ma pacific philippine 3 8 n 130 4 e 1 68 ma caroline pacific 16 9 n 141 4 e 0 54 ma the plate motions predicted by these new poles are compared with the spatial distribution of earthquakes and new focal mechanism solutions in the complex region where the philippine pacific and caroline plates intersect intermediate and deep focus earthquake hypocenters along the southern mariana arc show a southward decrease in the length of the seismic zone which qualitatively agrees with the predicted convergence rate as the pole of rotation is approached and as the effect of back arc spreading in the mariana trough disappears the absence of volcanism and intermediate depth seismicity along the southernmost mariana yap and palau sections of the plate boundary is attributed to very low convergence rates a new focal mechanism solution along the trench south of guam is the first clear underthrusting solution found along the mariana trench and agrees with the convergence direction implied by the pacific philippine pole of rotation no clear underthrusting focal mechanism solutions were found along the yap and palau trenches although three high angle thrust solutions demonstrate that compression is occurring in the upper plate perpendicular to the plate boundary

eddies in the red sea a statistical and dynamical study sea level anomaly sla data spanning 1992 2012 were analyzed to study the statistical properties of eddies in the red sea an algorithm that identifies winding angles was employed to detect 4998 eddies propagating along 938 unique eddy tracks statistics suggest that eddies are generated across the entire red sea but that they are prevalent in certain regions a high number of eddies is found in the central basin between 18 n and 24 n more than 87 of the detected eddies have a radius ranging from 50 to 135 km both the intensity and relative vorticity scale of these eddies decrease as the eddy radii increase the averaged eddy lifespan is approximately 6 weeks aes and cyclonic eddies ces have different deformation features and those with stronger intensities are less deformed and more circular analysis of long lived eddies suggests that they are likely to appear in the central basin with aes tending to move northward in addition their eddy kinetic energy eke increases gradually throughout their lifespans the annual cycles of ces and aes differ although both exhibit significant seasonal cycles of intensity with the winter and summer peaks appearing in february and august respectively the seasonal cycle of eke is negatively correlated with stratification but positively correlated with vertical shear of horizontal velocity and eddy growth rate suggesting that the generation of baroclinic instability is responsible for the activities of eddies in the red sea

seasonal variation and instability nature of the north pacific subtropical countercurrent and the hawaiian lee countercurrent 1 the relation between baroclinic instability of the north pacific subtropical countercurrent stcc and the hawaiian lee countercurrent hlcc and seasonal evolution of mesoscale sea surface height ssh variability was investigated by using historical hydrographic data and altimeter derived ssh anomaly data during 1992 2000 the annual and monthly mean dynamic height climatologies show two robust eastward flowing countercurrents the stcc extends typically along 24 n from 130 e to 160 w and slightly shifts to the north as it flows toward the east and the hlcc is located typically along 20 n and extends from about 150 e to just west of the hawaiian islands seasonal variations of the stcc in the western north pacific and the hlcc west of the hawaiian island where the eddy variability is relatively larger than the background were quite different the stcc hlcc is strong in winter summer to summer winter and weak in fall spring in contrast seasonal evolution of mesoscale ssh variability has almost the same cycle in the two countercurrent regions the eddy kinetic energy eke is a maximum in spring and a minimum in fall the dominant zonal scales are shortest in late winter and become longer with time a linear quasigeostrophic stability analysis using a three layer model indicates that instability properties are very similar between the two countercurrent regions the stcc and the hlcc become baroclinically more unstable during winter and late fall to winter respectively due to strong vertical velocity shear and weak stratification between the stcc hlcc and underlying westward flow and the most unstable wave during this season has an e folding timescale of about 2 3 months and a zonal wavelength of about 300 400 km the same behavior of the seasonal evolution of the mesoscale variability in the two countercurrent regions is a manifestation of these similarities in terms of increasing nonlinearity of the unstable waves and an inverse cascade of the eddy energy we discussed generation processes of the mesoscale ssh disturbances

late palaeogene quaternary geology of halmahera eastern indonesia initiation of a volcanic island arc the late palaeogene quaternary stratigraphy of halmahera is described and new formation names are proposed based on recent field investigations of the ne and central part of the island this stratigraphic information provides new insights into the neogene history of halmahera and the development of the present island arc the late palaeogene and younger rocks rest unconformably on an ophiolitic basement complex which formed part of a late cretaceous early tertiary fore arc after volcanic arc activity ceased in the eocene the former fore arc terrane was uplifted and deeply eroded in the late palaeogene some of the late palaeogene early miocene river valleys are currently being re excavated by the present rivers slow subsidence began in the mid late oligocene and by the end of the miocene all eastern halmahera was the site of shallow water carbonate deposition there is no evidence for arc volcanism in central halmahera at this time and the reported oligo miocene volcanism in nearby regions is interpreted as volcanism related to the sorong fault system the miocene shallow water region subsided rapidly in the early pliocene and the sedimentary basin formed was filled with marls succeeded by siliciclastic turbidites with increasing amounts of calc alkaline volcanic debris from a pliocene volcanic arc built on the western arms of halmahera probably on the eroded early tertiary arc this phase of rapid subsidence in the pliocene back arc region resulted from the initiation of subduction of the molucca sea lithosphere eastwards beneath halmahera differential subsidence on nw se and ne sw sets of faults in the region immediately behind the active arc led to the formation of deep sediment filled basins adjacent to the eastern arms a major deformation event in the pleistocene resulted in folding and local thrusting at the junction between eastern and western halmahera and volcanism ceased in the pliocene arc the third halmahera arc the quaternary arc currently active in the northern part of the islands began activity within the last 1 ma and is built upon the deformed and partly eroded pliocene arc the pleistocene deformation event and shift in position of the arc are interpreted as the result of the interaction of the eastward dipping molucca sea plate with adjacent plates either with a fragment of the australian continent in the sorong fault zone and or with the philippine sea plate beneath northern halmahera

subduction of seamounts at the java trench a view with long range sidescan sonar abstract we describe here a 1300 km by 45 km gloria long range sidescan sonar swath along the eastern java trench the swath images the trench axis a narrow strip of oceanic crust to the south and the toe of the accretionary wedge to the north between 108 and 120 e sonar images of the ocean crust show a pattern of normal faults typical of the outer wall of trenches these result from tension related to the bending of the oceanic lithosphere into the subduction zone a number of sub circular seamounts are also seen some of which are currently being subducted isolated ponds of flat lying sediments occur in the trench axis although along much of its length the trench is devoid of such sediment accumulations on the inner trench wall the accretionary wedge is recognised by its distinctive grainy texture with the grain aligned sub parallel to the deformation front where subducting seamounts are colliding with the wedge large crescentic areas of very high backscattering correlate with re entrants in the deformation front and large indentations in the wedge the high backscattering within these collision scars is interpreted to arise from outcropping strata and talus covered slopes resulting from erosion of an inner trench wall shortened and oversteepened by collision with a seamount all of the sediment ponds in the trench axis occur in close association with collision scars strongly suggesting localised erosion of the accretionary wedge in the scar areas however the volume of the indentations appears to be an order of magnitude greater than the volume of eroded sediments deposited in the trench indicating that erosion cannot be the primary mechanism by which indentations are created most of the missing material must be displaced landward by thrusting and folding ahead of the seamount our observations at the java trench are broadly comparable with those made at the japan trench by french and japanese workers however some differences in the detail of the collision process are evident in particular oversteepening and erosion occur from the earliest stage of collision at the java trench while uplift and understeepening initially dominate at the japan trench differences in the effects of subducting seamounts in the two areas are attributed to contrasts between the relatively unlithified strata of the java trench inner wall and the more lithified strata of the non accreting japan trench inner wall

a numerical study on the formation of upwelling off northeast taiwan 1 we examined the spatial and temporal variations of upwelling off northeast taiwan using a fine resolution numerical model with realistic bathymetry the zonally running shelf break in the area deflects the kuroshio seaward and produces upwelling on its on shelf edge the upwelling in turn manifests a cold dome or a cyclonic eddy in depths below 150 m or so the upwelling and hence the cyclonic eddy exist year round above this depth the eddy waxes and wanes as the upper portion of the kuroshio migrates seaward and shoreward respectively the eddy event fluctuates in a wide range of timescales seasonally the occurrence heavily favors summer rather than winter because the mean kuroshio axis migrates seaward in summer intraseasonally the fluctuation contains two dominant periods centered at 70 days and 30 days local wind forcing and channeling by two local canyons do not affect the eddy statistics significantly

terrane amalgamation in the philippine sea margin abstract the philippine sea plate includes plateaus of thickened crust interpreted as imbricated ophiolite and arc related terranes of late mesozoic early tertiary age separated by thinner oceanic crust the arrival of plateaus at the subducting southwest margin of the philippine sea plate has caused the philippine trench to propagate southward in increments and caused transfer of terranes to the philippine margin new data from the halmahera region indicate that the position nature and evolution of plate boundaries have been strongly influenced by the heterogeneous character of the philippine sea plate at present the philippine trench terminates at an oceanic plateau which is structurally continuous with an old forearc and ophiolite terrane on halmahera the position of this terrane has caused philippine sea plate eurasia convergence to be transferred from subduction at the philippine trench to the molucca sea collision zone through a broad ne sw dextral transpressional zone across halmahera this plate boundary configuration is unstable and requires the future development of a new subduction zone to the east of halmahera which will result in amalgamation of the halmahera ophiolite terrane to the philippine margin in the halmahera region amalgamation of terranes to the evolving philippine microcontinent is currently in process

upper ocean thermal structure and the western north pacific category 5 typhoons part i ocean features and the category 5 typhoons intensification abstract category 5 cyclones are the most intense and devastating cyclones on earth with increasing observations of category 5 cyclones such as hurricane katrina 2005 rita 2005 mitch 1998 and supertyphoon maemi 2003 found to intensify on warm ocean features i e regions of positive sea surface height anomalies detected by satellite altimeters there is great interest in investigating the role ocean features play in the intensification of category 5 cyclones based on 13 yr of satellite altimetry data in situ and climatological upper ocean thermal structure data best track typhoon data of the u s joint typhoon warning center together with an ocean mixed layer model 30 western north pacific category 5 typhoons that occurred during the typhoon season from 1993 to 2005 are systematically examined in this study two different types of situations are found the first type is the situation found in the western north pacific south eddy zone sez 21 26 n 127 170 e and the kuroshio 21 30

structural styles of an accretionary wedge south of the island of sumba indonesia revealed by seamarc ii side scan sonar the accretionary wedge south of sumba island indonesia is in the early stages of continent island arc collision australian continental shelf sediments are being actively accreted to the sunda arc at the timor trough we have correlated seamarc ii side scan images and bathymetry with 3 5 khz and seismic reflection profiles to construct a structural interpretation of this zone deformation is concentrated on the lower slope of the accretionary wedge within 15 to 25 km of the thrust front above which the strain rate appears to decrease abruptly three distinct structural styles are developed in the survey area the characteristics of the easternmost region are 1 deformation in a fold and thrust geometry 2 presence of mud volcanoes and mud ridges parallel to the thrust front indicating elevated fluid pressure and 3 the development of a long decollement extending 10 to 15 km from the thrust front in contrast the central region shows a more homogeneous thickening resulting mainly from closely spaced faulting seaward verging thrust faults and conjugate strike slip faults are the main structures in this segment of the accretionary wedge mud volcanoes and a very long decollement are absent in the central region we present a hypothesis in which structural style is controlled by the length of the decollement developed in front of the thrust front short thick thrust sheets may favor uniform shortening whereas long thin sheets may be unstable to buckling and deform by folding high fluid pressure may facilitate propagation of the decollement in contrast to the accretion occurring in the other two regions the western part of the accretionary wedge is in the process of being indented and redeformed by a basement ridge

on too fast baroclinic planetary waves in the general circulation abstract recent altimetric observations of the ocean surface reveal signatures of long planetary waves near the annual frequency band comparisons of the observed wave speeds and those predicted by standard linear theory suggest that the latter is inadequate as it yields different westward speeds than those measured in the extratropical latitudes the predicted speeds are typically slower than the observations here the problem of long baroclinic wave propagation in a forced stratified ocean is considered theoretically with a view toward explaining these observations of too fast planetary waves from a quasigeostrophic analysis it is argued that baroclinic waves in a sheared environment are accelerated to the west via their interactions with both the mean advective field and the mean potential vorticity field conditions under which the ratio of actual to linear phase speeds matches the observed ratio are computed and found to be typical of the open ocean extensions of these ideas to continuously st

topex poseidon observations of mesoscale eddies over the subtropical countercurrent kinematic characteristics of an anticyclonic eddy and a cyclonic eddy 1 relative dynamic heights and geostrophic fields were derived from topex poseidon altimetry data and then used to track mesoscale eddies over the subtropical countercurrent stcc the radii centers vorticities shearing deformation rates stretching deformation rates divergences and center velocities of all identified eddies over the stcc were determined using a model that assumes constant velocity gradients most eddies are concentrated in a zonal band near 22 n and there is an interannual variation in the number of eddies a case study was made for a cyclonic eddy and an anticyclonic eddy with time series of eddy kinematic parameters computed both eddies survive for 220 days and propagate westward along over 22 n 24 n to reach the kuroshio current east coast of taiwan where the eddies were dissipated and in turn affected the kuroshio current in many ways sea surface temperature data and drifter data confirm the existence of these two eddies the radii of both eddies vary and their shapes are mostly elliptical during propagation the anticyclonic eddy propagated almost westward with oscillating north south components and the mean speed is 8 3 km day the cyclonic eddy moved southwestward before reaching 130 e and then moved northwestward with a mean speed of 7 6 km day the propagations of these two eddies are basically consistent with the standard theory of eddy propagation but with larger speeds the propagating direction could be altered while passing steep bottom topography or merging with the other eddies index terms 4520 oceanography physical eddies and mesoscale processes 4576 oceanography physical western boundary currents 4512 oceanography physical currents 4594 oceanography physical instruments and techniques 4556 oceanography physical sea level variations

demographics of mesoscale eddies in the california current 1 demographics and variability of persistent mesoscale eddies in the california current have been investigated in a systematic manner using a decade 1995 2004 of merged satellite altimeter data the number of persistent eddies formed each year varied almost 3 fold 4 fold for cyclones anticyclones and was strongly modulated by the 1997 1998 el nino event over the 10 year period cyclone formation was maximum in both winter and summer while maximum anticyclone formation occurred only in winter the majority of long lived eddies 70 day lifespan originated seaward of the 1000 m isobath and with the exception of 2 anticyclones did not form between 45 and 50 n maximum westward propagation of long lived eddies was almost 800 km with similar mean propagation speeds for cyclones and anticyclones

numerical experiments on the movement of a warm core ring with the bottom slope of a western boundary numerical experiments are performed to investigate the effects of the bottom slope of a western boundary on realistic warm core rings using a primitive equation sigma coordinate model warm core rings which initially have baroclinic velocity near a steep bottom slope gradually move northward but those with barotropic velocity do not barotropic velocity on the slope immediately disperses as a topographic rossby wave while baroclinic velocity is retained since the northward movement is caused by an effect very much like the image effect which is originally the effect of a free slip wall the authors term this effect the equivalent image effect the equivalent image effect increases as a slope becomes steeper and bottom friction becomes weaker and vice versa it seems that a steep slope acts like a wall and the bottom friction of a steep slope corresponds to the lateral viscous effect of a wall however the effect of a slope on a warm core ring is different from that of a wall in that ring slope interactions take place at the lower part of the ring because the velocity of a warm core ring is weak in deep layers ring slope interactions are moderate and the leakage of the interior fluid of a ring seen in ring wall interactions is not apparent while the viscous effect is weaker than that of a no slip wall as well these results are applied to the northward movement of kuroshio warm core rings and to warm eddies in the gulf of mexico

frequency dependent amplification of unsaturated surface soil layer this paper presents a study of the amplification of sv waves obliquely incident on a surface soil layer overlying rock formation special attention is placed on the influence of the saturation states of the soil layer and the bedrock on the amplification in both horizontal and vertical directions as well as on the amplitude ratios between the two directions at the surface where the vertical and horizontal amplification and the amplitude ratios are expressed as functions of the frequency of incident waves the analysis indicates that while the influence of the saturation state of the bedrock is insignificant a change of the saturation state of the soil layer may have a marked impact on the vertical amplification for typical seismic frequencies an unsaturated soil layer can generate greater vertical amplification than a saturated layer it can also cause larger amplitude ratios between vertical and horizontal components at the surface the analysis further confirms the potential importance of the saturation condition of near surface soils in site response analysis

the southern termination of the philippine trench abstract recent studies of the southern end of the philippine trench using gloria sidescan sonar and single channel seismic data and geological studies on the island of halmahera suggest that the trench is in the process of propagating south and that some of the ese wnw convergence is transferred via a broad ne sw zone of dextral strike slip across northern halmahera into the molucca sea collision zone ne sw ridges and lineaments on the seafloor can be traced into major faults and structural trends on land the bathymetric expression of the philippine trench is lost where it meets an oceanic plateau on the philippine sea plate this elevated and probably thickened plateau appears to have inhibited any further propagation of the trench southwards to the north of the plateau there is a well developed accretionary prism but to the south deformation of sediments on the seafloor is less intense a prominent ridge with sediments passively banked up against it marks the southern limit of deformation associated with the philippine trench to the south lies the eastern halmahera waigeo ophiolite terrane an area of shallow water and islands underlain by ophiolitic basement between halmahera and the sorong fault zone there are no bathymetric or structural features to indicate any form of active link between the philippine trench and the sorong fault through or along the northern side of this ophiolite terrane there is no earthquake evidence for any form of fault linking the philippine trench to either the palau trench or the sorong fault but there are numerous earthquake epicentres reported between the southern end of the trench and the molucca sea the island of halmahera is considered to lie in a diffuse boundary zone at the margin of the philippine sea plate continued collision of the opposing arcs in the molucca sea will ultimately prevent further e w convergence between halmahera and sulawesi it is predicted that either the philippine trench will propagate south along its present line to meet the sorong fault or that another trench will develop further to the east in either case the arc and ophiolite terrane of halmahera might then be accreted onto the eurasian margin

eddy kuroshio interactions local and remote effects quasi geostrophic mesoscale eddies regularly impinge on the kuroshio in the western north pacific but the processes underlying the evolution of these eddy kuroshio interactions have not yet been thoroughly investigated in the literature here this interaction is examined with results from a semi idealized three dimensional numerical model and observations from four pressure sensor equipped inverted echo sounders piess in a zonal section east of taiwan and satellite altimeters both the observations and numerical simulations suggest that during the interaction of a cyclonic eddy with the kuroshio the circular eddy is deformed into an elliptic shape with the major axis in the northwest southeast direction before being dissipated the poleward velocity and associated kuroshio transport decrease and the sea level and pycnocline slopes across the kuroshio weaken in contrast for an anticyclonic eddy during the eddy kuroshio interaction variations in the velocity sea level and isopycnal depth are reversed the circular eddy is also deformed to an ellipse but with the major axis parallel to the kuroshio the model results also demonstrate that the velocity field is modified first and consequently the ssh and isopycnal depth evolve during the interaction furthermore due to the combined effect of impingement latitude and realistic topography some eddy kuroshio interactions east of taiwan are found to have remote effects both in the luzon strait and on the east china sea shelf northeast of taiwan

blocking and westward passage of eddies in the luzon strait satellite observations have shown the abundance of generally westward propagating eddies in the subtropical regions in the north pacific ocean especially north of 10 n eddies transport mass and can significantly impact the circulation as well as the heat salt and nutrient balances of the western pacific marginal seas this paper uses a numerical model to examine the conditions when eddies can or cannot freely propagate westward through the luzon strait into the south china sea scs composite analyses on the 10 year model data show that the fates of eddies depend on the strength and path of the kuroshio in one path that exists mostly during fall and winter the kuroshio loops westward into the scs the potential vorticity pv across the current is weak and eddies are likely to propagate freely through the luzon strait in another path which exists mostly during spring and summer the kuroshio tends to leap directly northward bypassing the scs the pv across it strengthens and eddies are then blocked and are constrained to also follow the northward path nonlinear eddy current interaction and the existence of a cyclone north of the luzon island during the looping phase explain why eddies of both signs can pass through the strait it is shown also that the upstream state of the kuroshio in the western tropical pacific plays an important role in dictating the different paths of the kuroshio the looping leaping path is caused by a weakened stronger kuroshio transport related to the northward southward shift of the north equatorial current in wintertime summertime

observed and simulated kinematic properties of loop current rings two rings shed by the loop current in 1980 and 1982 were observed for several months by satellite tracked drifters to migrate across the gulf of mexico the drifter path data have been inverted to obtain estimates of the paths of the centers of the two rings ring shape and the swirl velocities three drifters were deployed in the 1980 ring and the analysis of that data set establishes the variability of the above kinematic estimates for one ring a comparison of the analysis of data from both rings provides some idea on inter ring variability both rings impacted the mexican continental slope at about 22 8 n 95 5 w after a brief adjustment period both rings reestablished and maintained a vortex character for several months in the slope region while migrating slowly to the north the paths of the centers of the two rings along the slope are virtually identical the same analysis routine was applied to some simulated drifter data obtained from the hurlburt and thompson 1980 gulf of mexico primitive equation model in the midgulf the agreement between the observed rings and the simulated ring is good although the former showed stronger interaction with the continental slope topography and or circulation than was seen in the latter along the slope the model ring kinematic characteristics were in extraordinary agreement with the observations

subsurface structure of the solfatara volcano campi flegrei caldera italy as deduced from joint seismic noise array volcanological and morphostructural analysis 1 the joint application of different seismological techniques for seismic noise analysis and the results of a volcanological and morphostructural survey have allowed us to obtain a detailed and well constrained image of the shallow crustal structure of the solfatara volcano campi flegrei caldera italy horizontal to vertical spectral ratios inversion of surface wave dispersion curves and polarization analysis provided resonance frequencies and peak amplitudes shear wave velocity profiles and polarization pattern of coherent ambient noise these results combined in a unique framework indicate that the volcanic edifice is characterized by lateral and vertical discontinuities and heterogeneities in terms of shear wave velocity lithological contrasts and structural setting the interpretation of the seismological results with the volcanological and morphostructural constraints supports the hypothesis that the volcano has been characterized by a complex and intense activity with the alternation of constructive and destructive phases during which magmatic and phreatomagmatic explosions built a complex tuff cone later reworked by atmospheric agents and altered by hydrothermal activity the differences in the velocity structure between the central and eastern parts of the crater have been interpreted as resulting from a possible eastward migration of the eruptive vent along the deformational features affecting the area and to the presence of viscous lava and lithified tuff bodies within the feeding conduits which are buried under a covering of reworked materials of variable thickness the observed fault and fracture systems partially inherited from regional structural setting and exhumed during volcanism and ground deformation episodes also seems to strongly control wave propagation affecting the noise polarization properties

seasonal response of the southern east china sea shelf water to wind modulated throughflow in the taiwan strait seasonal change of the southern east china sea ecs shelf water and its relation to the throughflow in the taiwan strait ts was examined based on comparative experiments with inserting passive tracers into a regional ocean model through analyzing the model output results we found that from autumn to winter strong northeasterly wind over the ts significantly weakens the outflow from the ts i e flowing into the ecs and the kuroshio water intrudes farther shoreward across the northern shelf of taiwan in response to the weakened outflow on the other hand water flowing into the shelf from the ts extends further offshore from spring to summer when the ts throughflow is enhanced by a wind change from northeasterly to southwesterly and the kuroshio water retreats seaward off the shelf due to the offshore extension of the shelf water it suggests that the weakening strengthening of the ts throughflow could allow inhibit shelf ward kuroshio water onto the northeastern shelf of taiwan emphasizing that the throughflow modulated by a local wind can be an important factor controlling the seasonal variation of the southern ecs shelf water

interpretation of seismic vertical amplification observed at an array site strong ground motions were recorded at port island kobe by a borehole array during the 1995 hyogo ken nanbu kobe earthquake these records indicate that while the horizontal peak accelerations were reduced as seismic waves traveling from the bottom to the surface motions in the vertical direction were significantly amplified at the surface with peak value of 1 5 to 2 times larger than the horizontal components some studies have discussed local site effects on the horizontal motions whereas the available study on the vertical amplification is limited in this article we present a possible mechanism to explain the observed vertical amplification in detail we consider that the observed large vertical amplification is mainly associated with incomplete saturation of near surface soils which causes substantial amplification of p waves but does not affect the propagation of s waves based on the concept of homogeneous pore fluid and biot s theory of two phase media we discuss the characteristics of p wave velocity poisson s ratio and degree of saturation in shallow soil layers and show evidence of incomplete saturation of near surface soils at the array site we analyze a simple model to theoretically investigate the effects of saturation on vertical motion amplification the results show that the degree of saturation may produce substantial influence on the amplification both amplitude and frequency content using a solid fluid coupled finite element procedure we perform a simulation of the observed vertical motions at the array site by including the effects of saturation the results demonstrate the mechanism of large amplification caused by incomplete saturation of near surface layers the present study indicates that vertical component motions may significantly be affected by pore water saturation of soils suggesting that we may need to carefully examine the condition of saturation in the study of vertical site amplification manuscript received 24 may 1999

eddies in the eastern gulf of alaska from topex poseidon altimetry eddy activity in the gulf of alaska goa is evidenced to fluctuate with the el nino southern oscillation enso cycle altimetry from topex poseidon is used to study eddy formation along a single descending track in the far eastern goa from late 1992 through late 1998 the track is sampled between 45 n and 60 n where it is roughly parallel to the eastern boundary the geoid and mean currents are removed from the data through extraction of the temporal mean at each point the resulting anomalies are passed through a matched filter designed to detect gaussian signals embedded in noise the filter is optimized to detect eddies with amplitude 10 cm and diameters roughly 50 350 km both anticyclonic and cyclonic structures are examined the distribution of eddies in space is similar for both anticyclonic and cyclonic eddies with most occurring between 50 n and the northern limits of the goa few eddies of either sign were found south of 50 n anticyclonic eddies are stronger and have a broader distribution of amplitudes typically 5 30 cm compared to cyclonic features which are more symmetrically distributed over 5 15 cm the detection of weak 15 cm eddies is sensitive to the filter threshold but detection of larger amplitude eddies is robust the average amplitude of anticyclonic eddies increases following the 1993 1994 1995 and 1998 el nino events eddy amplitude appears to vary with enso strength the strongest eddies detected form in early 1998 these results support previous numerical studies of eddy development in the eastern goa

the stability of the horizontal to vertical spectral ratio of triggered noise and earthquake recordings the aim of this work is to analyze the stability of the amplification function obtained by the horizontal to vertical spectral ratio hvsr for a sedimentary site with a simple geomorphological situation we have estimated the stability of the hvsr analyzing two years of data composed of 674 triggered noise records man made seismic waves strong enough to reach the threshold set for earthquake detection and 132 earthquakes local regional and teleseismic events the resonance peaks obtained with the two different data sets converge on an average both in frequency and amplitude we examined and rejected the possible presence of periodicity of the fundamental frequency in the time sequences and its relevant amplification obtained by the hvsr of both triggered noises and earthquakes then we performed a correlation analysis between these sequences and other parameters in particular they have been correlated with signal amplitude rainfall and magnitude for earthquakes only a weak negative correlation has been estimated between the rainfall and fundamental frequency and between the fundamental peak9s amplification and magnitude finally we validated the hvsr transfer function with a 1d model using a v s profile obtained with the noise analysis of surface wave technique louie 2001

noncohesive critical coulomb wedges an exact solution active fold and thrust belts or submarine accretionary complexes can be modeled as critically tapered wedges of material on the verge of coulomb failure everywhere overlying a basal decollement where frictional sliding is occurring ignoring cohesion the four strength parameters needed to describe a critical coulomb wedge are its internal and basal coefficients of friction and b and its internal and basal hubbert rubey fluid pressure ratios and b an exact relation between surface slope and basal dip of a noncohesive critical wedge with uniform properties is derived the state of stress within such a wedge has the same orientation everywhere and is constant if is and vice versa a coefficient of internal friction 1 1 is consistent with the known surface slope basal dip and pore fluid pressures in the active fold and thrust belt of western taiwan assuming that byerlee s law b 0 85 is valid on the base the wide variety of tectonic styles observed to occur along convergent margins including subduction erosion active accretion subduction without accretion and even extension and normal faulting may be controlled by relatively small spatial or temporal variations in either b or b

altimeter observations of the bering slope current eddy field topex altimeter data is analyzed to describe the mesoscale eddy field associated with the bering slope current in the central bering sea the observed eddy field is well defined seasonally modulated and interannually variable the most energetic mesoscale eddy activity typically occurs during the spring and summer months and is characterized by a peak along isobath wavelength of 212 km and a representative wave period of 4 months spatial variability of annual period phase indicates that the axis of bering slope current exhibits seasonal offshore migration

basin formation and neogene sedimentation in a backarc setting halmahera eastern indonesia abstract it has been proposed that basins in backarc settings form in association with subduction by thinning of continental crust by backarc spreading in oceanic crust by compression retro arc basins or by trapping of pieces of oceanic plate behind an arc the halmahera basin in eastern indonesia developed in a backarc setting but does not fall into any of these categories it formed by subsidence of thickened crust made up of imbricated mesozoic palaeogene arc and ophiolite rocks halmahera lies at the western edge of the philippine sea plate in a complex zone of convergence between the eurasian margin the oceanic plates of the west pacific and the australian indian plate to the south the basement is an imbricated complex of mesozoic to palaeogene ophiolite arc and arc related rocks during the miocene this basement complex formed an area of thickened crust on which carbonate reef and reef associated sediments were deposited we interpret this shallow marine region of thickened crust to be similar to many of the oceanic plateaux and ridges found within the philippine sea plate to day in the late miocene convergence between the philippine sea plate and the eurasian margin resulted in the formation of the halmahera trench to the west of this region of thickened crust subduction of the molucca sea plate at the trench caused the development of a volcanic island arc subsidence in the backarc area produced a broad sedimentary basin filled by clastics eroded from the arc and from uplifted basement and cover rocks the basin was asymmetric with the thickest sedimentary fill on the western side against the volcanic arc the halmahera basin was modified in the plio pleistocene by east west compression as the molucca sea plate was eliminated by subduction

interannual variations of kuroshio transport in the east china sea and its relation to the pacific decadal oscillation and mesoscale eddies results of a data assimilative ocean model jcope2 from 1993 to 2012 were used to examine the correlation between the pacific decadal oscillation pdo index and interannual variations of the kuroshio transport in the east china sea ecs and the influences of mesoscale eddies on this correlation in a period from 1993 to 2002 the kuroshio transport estimated from the jcope2 reanalysis has a positive correlation with the pdo index this well known correlation became weak or even disappeared when the analysis period was extended from 1993 2002 to 1993 2012 this occurs because the variation range of the pdo index became small during enhanced mesoscale eddy activity southeast of taiwan in years after 2002 the eddies caused a larger variation in the kuroshio transport in the years after 2002 than before 2002 and therefore changed the correlation between the pdo index and kuroshio transport in the ecs the influence of mesoscale eddies on the kuroshio transport has strong regional dependence the kuroshio transport from the area east of taiwan to the midway along the shelf break in the east china sea depends mainly on eddies arriving from southeast of taiwan while transport from the midway along the shelf break to the tokara strait depends mainly on the eddies arriving from northeast of okinawa island the combination of pdo related signals and eddy related signals determines the interannual variations of the kuroshio transport in the ecs and sufficient attention must be paid to the spatial dependence of the kuroshio transport in the ecs on eddies

mesoscale eddies in the northern south china sea a fine grid resolution model with realistic bathymetry and forcing has been developed to study the characteristics of the mesoscale eddies for the northern south china sea scs the scs model derives its open boundary conditions from a larger scale model which minimizes errors related to the uncertainty of the kuroshio intrusion at the open boundaries the model results are consistent with previous observations model sea surface height anomaly demonstrates that the hydrography and circulation in the northern scs are modulated by westward propagating mesoscale eddies originating in the vicinity of the luzon strait this explains the observed intra seasonal fluctuations at the southeast asian time series study seats station the mesoscale eddies have the same propagation speed as baroclinic rossby waves 0 1 ms 1 the periods of eddy shedding estimated from strouhal number are around 40 50 days in december and 80 120 days in august respectively the seasonal variability of the kuroshio intrusion results in more eddies in winter than in summer r 2007 elsevier ltd all rights reserved

seasonal and interannual changes of the kuroshio intrusion onto the east china sea shelf an advanced artificial neural network classification algorithm is applied to 20 years of multisatellite geostrophic velocity data to study the kuroshio intrusion onto the southern shelf of the east china sea the results suggest that the on shelf intrusion may occur year round but winter intrusion events are more frequent than summer events both stronger intrusion which is closely correlated to surface heat flux gradient and weaker intrusion which is correlated to wind forcing occur during wintertime but the former dominates in late winter while the latter prevails in early winter there is a significant year to year variation of the winter on shelf intrusion although on shelf intrusion is the major characteristic of the region during wintertime seldom intrusion events have been identified in the winters of 1997 1998 and 2002 2003 two conditions are responsible for the cause of the nonintrusion events during the two nonintrusion winters the upstream kuroshio transport anomaly is insignificant the kuroshio is not weakened and no significant winter cooling off northeast taiwan thus the kuroshio tends to flow along the shelf break following the 200 m isobath and on shelf intrusion ceases those two nonintrusion events take place during the winters when both the nino 3 4 index and the pdo index are large and positive

fluctuations of the thermal fronts off northeastern taiwan 1 a high resolution sea surface temperature sst data derived from several satellites is used to investigate the variability of the thermal front off northeastern taiwan hidden by a dominant annual cycle the sst data cannot reveal the thermal front fluctuation in the form of hovmoller diagram an innovative methodology has been applied to the sst satellite imagery to derive the sst standardized index sstsi capable of revealing the frontal variability with multiple time scales principal component analysis shows that the sstsi variation consists mainly of two modes mode 1 represents a strong annual cycle related to the seasonal reversal of the monsoonal winds the temperature gradient is enhanced in winter and a cold dome is observed off northern taiwan in summer mode 2 is highly correlated with the upstream kuroshio variability the shoreward seaward migration of the thermal front takes place when the kuroshio transport weakens strengthens the results are consistent with transports estimated by tidal gauge measurements satellite altimeter based sea level anomaly and surface flow patterns derived from high frequency radars mode 2 is coherent with the kuroshio transport through the east taiwan channel at periods of 120 and 45 d with a time lag of 40 and 11 d respectively this 120 d fluctuation is due to the interaction between westward propagating eddies and the kuroshio east of taiwan while the 45 d signal arises from the kuroshio s self instability the interannual variations of the sst pattern in winter and summer are also discussed

effects of mesoscale eddies on the volume transport and branch pattern of the kuroshio east of taiwan using satellite altimeter data and a long term altimetric transport index for the kuroshio inflow northeast of taiwan the effects of mesoscale eddies on the kuroshio volume transport kvt at the east taiwan channel and the branching pattern of the kuroshio east of taiwan are investigated at scales from those of individual events to interannual timescales both anticyclonic and cyclonic eddies are found to be able either to strengthen or weaken the kvt depending on the relative strength of mass convergence and divergence produced upstream and downstream of the eddies the major factor influencing the intensity of the kuroshio inflow is the meridional location of the eddies for single eddy events the kvt is significantly correlated with the latitude of the eddy s center the correlations being 0 44 and 0 48 for anticyclonic and cyclonic eddies respectively for dipole eddy events when the direction angle falls in the interval 40 150 240 300 the kvt anomaly tends to be positive negative furthermore low kvt events generally correspond to the formation of the ryukyu current branch which is also generated from strong mass divergence produced by the eddies in addition on interannual time scales the variation of kvt is closely related to the relative number of anticyclonic to cyclonic eddies west of 125 e with a correlation of 0 5 this article is protected by copyright all rights reserved

main eddy vertical structures observed in the four major eastern boundary upwelling systems in the four major eastern boundary upwelling systems ebus mesoscale eddies are known to modulate the biological productivity and transport near coastal seawater properties toward the offshore ocean however little is known about their main characteristics and vertical structure this study combines 10 years of satellite altimetry data and argo float profiles of temperature and salinity and our main goals are i to describe the main surface characteristics of long lived eddies formed in each ebus and their evolution and ii to depict the main vertical structure of the eddy types that coexist in these regions a clustering analysis of the argo profiles surfacing within the long lived eddies of each ebus allows us to determine the proportion of surface and subsurface intensified eddies in each region and to describe their vertical structure in terms of temperature salinity and dynamic height anomalies in the peru chile upwelling system 55 of the sampled anticyclonic eddies aes have subsurface intensified maximum temperature and salinity anomalies below the seasonal pycnocline whereas 88 of the cyclonic eddies ces are surface intensified in the california upwelling system only 30 of the aes are subsurface intensified and all of the ces show maximum anomalies above the pycnocline in the canary upwelling system 40 of the aes and 60 of the ces are subsurface intensified with maximum anomalies extending down to 800 m depth finally the benguela upwelling system tends to generate 40 50 of weak surface intensified eddies and 50 60 of much stronger subsurface intensified eddies with a clear geographical distribution the mechanisms involved in the observed eddy vertical shapes are discussed

fourier and wavelet analyses of topex poseidon derived sea level anomaly over the south china sea a contribution to the south china sea monsoon experiment we processed 5 6 years of topex poseidon altimeter data and obtained time series of sea level anomaly sla over the south china sea scs fourier analysis shows that sea level variability of the scs contains major components with periods larger than 180 days and is dominated by the annual and semiannual components tidal aliasing creates 30 180 day components that can be misinterpreted as wind induced variabilities continuous and multiresolution wavelet analyses show that the sla of the scs has monthly to interannual components of time varying amplitudes and the regional slope of sla is 8 9 mm yr 1 which may be caused by the decadal climate change coherences of sla with wind stress anomalies wsa and sea surface temperature anomalies sta are significant at the annual and semi annual components at periods of 2 5 years the wavelet coefficients of sla wsa and sta have the same pattern but wsa leads sla and sta follows sla the zero crossing of sla in spring is highly correlated with the onset of the summer monsoon the interannual variability of sla is correlated with el nino southern oscillation and most important is that when the el nino like wavelet coefficients of sla over the warm pool northeast of australia or the scs change curvature from negative to positive an el nino is likely to develop this is a contribution to the south china sea monsoon experiment scsmex

seismotectonics of new guinea a model for arc reversal following arc continent collision the structure and evolution of the northern new guinea collision zone is deduced from international seismological center isc seismicity 1964 1985 new and previously published focal mechanisms and a reexamination of pertinent geological data a tectonic model for the new guinea margin is derived which illustrates the sequential stages in the collision and suturing of the bewani toricelli adelbert finisterre huon new britain arc to central new guinea followed by subduction polarity reversal in the west east of 149 e the solomon plate is being subducted both to the north and south bringing the new britain and trobriand forearcs toward collision west of 149 e the forearcs have collided and together they override a fold in the doubly subducted solomon plate lithosphere which has an axis that is parallel to the strike of the ramu markham suture and that plunges westward at an angle of 5 beneath the coast ranges of northern new guinea active volcanism off the north coast of new guinea is related to subduction of the solomon plate beneath the bismarck plate active volcanism of the papuan peninsula and quaternary volcanism of the new guinea highlands are related to slow subduction of the solomon plate beneath the indo australian plate along the trobriand trough and the trough s former extension to the west respectively from 144 148 e seismicity and focal mechanisms reveal that convergence between the sutured bismarck and indo australian plates is accommodated by thrusting within the finisterre and adelbert ranges and compression of the new guinea orogenic belt together with basement involved foreland folding and thrusting to the south the finisterre block overthrusts the new guinea orogenic belt whereas the adelbert block is sutured to new guinea and overthrusts the oceanic lithosphere of the bismarck sea along the new guinea trench west of 144 e seismicity defines a southward dipping wadati benioif zone and focal mechanisms indicate oblique subduction only this oldest westernmost portion of the collision has progressed past suturing to a full reversal in subduction polarity

propagation of big island eddies using satellite altimetry data we have observed a series of anticyclonic eddies as they form at the big island of hawaii and have tracked them as they move away from the island while similar eddies have been observed near the hawaiian islands in previous studies the fate of the anticyclonic eddies has previously been unclear the eddies that we observed initially propagated to the southwest but consistently changed propagation direction to the northwest later in their lifetimes this was intriguing to us as theoretically the decay of isolated anticyclonic eddies on a plane should cause them to continually move toward the southwest such isolated eddy dynamics are unable to account for the observed change to northwestward eddy propagation and the presence of the westward flowing north equatorial current turns out to be important to the big island eddy dynamics the eddies are not passively advected by the north equatorial current rather the mean flow changes the propagation characteristics of the eddies an existing theory that includes meridionally varying purely zonal mean flow is shown to account for the observed propagation of the big island eddies if the zonal variation of the mean flow is considered

a model for the analysis of drifter data with an application to a warm core ring in the gulf of mexico a model developed primarily for the analysis of drifter data is discussed the model is based on a parametric representation of the drifter velocity in terms of monge potentials two of which are constants following the motion of the fluid in the application presented here one of the potentials is taken as the frequency of rotation about a ring by a parcel a more restricted interpretation of the velocity gradient in variant for horizontal flow is also discussed the other potential is taken as the streamline of a parcel that is locally approximated as a conic section for the restricted interpretation solutions to the model equations are critically dependent on the relative sizes of the squares of the vertical vorticity and the total deformation rate this model differs from drifter cluster models in that each drifter provides independent estimates of the vorticity and deformation rates application is made to path data from three drifters that were seeded in a warm core ring in the gulf of mexico in november 1980 the model provided estimates of the ring translation and swirl velocities along with the ring geometry the analysis showed that the ring was persistently elliptical with the major axis aligned in the east west direction a satellite infrared photo on january 21 1981 confirmed this orientation

satellite altimetry the marine geoid and the oceanic general circulation for technical reasons the general circulation of the ocean has historically been treated as a steady laminar flow field the recent availability of extremely highaccuracy and high precision satellite altimetry has provided a graphic demonstration that the ocean is actually a rapidly time evolving turbulent flow field to render the observations quantitatively useful for oceanographic purposes has required order of magnitude improvements in a number of fields including orbit dynamics gravity field estimation and atmospheric variability with five years of very high quality data now available the nature of oceanic variability on all space and time scales is emerging including new findings about such diverse and important phenomena as mixing coefficients the frequency wavenumber spectrum and turbulent cascades because the surface elevation is both a cause and consequence of motions deep within the water column oceanographers soon will be able to provide general circulation numerical models tested against and then combined with the altimeter data these will be complete three dimensional timeevolving estimates of the ocean circulation permitting greatly improved estimates of oceanic heat carbon and other property fluxes

nature and distribution of deformation across the banda arc australian collision zone at timor recently acquired seismic reflection and seamarc ii side scan and swath bathymetry profiles near timor show that the banda arc australia collision zone has a tectonic framework similar to that of a typical oceanic subduction system deformation is occurring at present most intensely at the foot of the inner slope of the timor trough this deformation front is discontinuously advancing southward as new thrust slices develop within the subducted australian margin strata in contrast present deformation is apparently negligible in the savu basin the complex fore arc basin north of timor a possible significant exception is a postulated right lateral northeast trending fault zone offsetting the outer arc high between savu and roti although back arc thrusting has been documented north of the volcanic arc this component of convergence is minor compared with the scale of ongoing deformation in the timor trough the detailed nature of these surveys has also led to the recognition of along strike variations in deformation in the timor trough and in the savu basin these variations may be related to the variable degree of involvement of the australian continental margin along the arc

circulations and eddies over the south china sea derived from topex poseidon altimetry topex poseidon t p altimeter data were used to derive time varying circulation and eddies over the south china sea scs for 1993 1999 large variabilities of sea surface heights and dense distribution of eddies were found to occur along a band across the scs basin a cross over method is introduced to compute pointwise velocity components the t p derived circula tions and eddies are consistent with the drifter results from the world ocean circulation experi ment data center 1 because of monsoons the scs circulation is largely cyclonic in winter is largely anticyclonic in summer and is modulated interannually by el nifio southern oscillation 2 both cold and warm core eddies were found in the waters east of vietnam west of luzon and west of the luzon strait but their times of occurrence and the way they evolved vary interannually 3 the reversal of the alongshore currents east of vietnam was in complete accordance with wind stress the locations and kinematic properties of eddies over scs were estimated by the least squares method the averaged vorticities of the cold and warm core eddies are 1 684x 10 6 and 1 738x l0 6 tad s respectively and the shearing and stretching deformations are one thousandth of the vorticities the angular velocity of eddy decreases with increasing radius coherence analy sis suggests that the interannual and seasonal variations of circulation are largely due to wind stress and the semi annual variation is largely due to wind stress curl the angular velocities of eddies over the central scs basin are coherent with the magnitudes and signs of wind stress curl the seasonal steric anomaly was also computed and its spatial pattern and scale are quite different from those of circulation and eddy

spatial and temporal variations of the kuroshio east of taiwan 1982 2005 a numerical study 1 a 1 8 east asian marginal seas model nested to a larger domain north pacific ocean model is implemented over a span of 24 years from 1982 to 2005 to investigate the spatial and temporal variations of the kuroshio east of taiwan between 22 and 25 n the mean state and variability of the kuroshio such as the two paths observed in the trajectories of surface drifters southeast of taiwan and the branching of the kuroshio northeast of taiwan are well reproduced by the model southeast of taiwan the kuroshio is mostly in the top 300 m in the inshore path but extends to 600 m in the offshore path northeast of taiwan the kuroshio follows the shelf edge in the east china sea but may branch along a path south of the ryukyu islands the latter path often meanders southward and a significant portion of the kuroshio transport may be diverted to this path the kuroshio extends from the coast to 123 123 5 e between 22 and 25 n with currents reaching a depth of 1000 m at some latitudes the kuroshio transports averaged over five sections east of taiwan are 28 4 5 0 sv and 32 7 4 4 sv with and without the contribution from the countercurrent respectively

effects of the stcc eddies on the kuroshio based on the 20 year jcope2 reanalysis results abstract in this study 20 years of model reanalysis data are analyzed to study the effects of the subtropical countercurrent stcc eddies on the upstream kuroshio from east of luzon to east of taiwan the effects are assessed from individual events to interannual time scales the wind driven kuroshio is modified by the stcc eddies with high spatiotemporal variations the mass balance in the composite eddy events indicates that the strengthening and weakening of the kuroshio transport are locally caused by the mass convergence and divergence produced by the eddies the same analogy applies to the interannual time scale in the eddy rich years the upstream kuroshio is generally stronger because of wind forcing yet the strengthening is nonuniform because of modification by the eddies the larger number of warm eddies to the east of taiwan and luzon island further strengthen the jet whereas the larger number of cold eddies to the east of the luzon strait weaken the kuroshio in the luzon strait drifter trajectories show larger luzon strait intrusion during the occurrence of cold eddies the local weakening of the kuroshio by cold eddies leads to a weaker potential vorticity jump producing favorable conditions for the intrusion of a water mass into the south china sea

large scale variability in the midlatitude subtropical and subpolar north pacific ocean observations and causes abstract altimetric data from the 8 yr topex poseidon t p mission oct 1992 jul 2000 are used to investigate large scale circulation changes in the three current systems of the midlatitude north pacific ocean the north pacific current npc the alaska gyre and the western subarctic gyre wsg to facilitate the understanding of the observed changes a two layer ocean model was adopted that includes first mode baroclinic rossby wave dynamics and barotropic sverdrup dynamics the npc intensified steadily over the t p period from 1992 to 1998 much of this intensification is due to the persistent sea surface height ssh drop on the northern side of the npc a similar ssh trend is also found in the interior of the alaska gyre both of these ssh changes are shown to be the result of surface wind stress curl forcing accumulated along the baroclinic rossby wave characteristics initiated from the eastern boundary in addition to the interior ssh signals the intensity of the alaska gyre is shown to depend

the interaction of supertyphoon maemi 2003 with a warm ocean eddy understanding the interaction of ocean eddies with tropical cyclones is critical for improving the understanding and prediction of the tropical cyclone intensity change here an investigation is presented of the interaction between supertyphoon maemi the most intense tropical cyclone in 2003 and a warm ocean eddy in the western north pacific in september 2003 maemi passed directly over a prominent 700 km 500 km warm ocean eddy when passing over the 22 n eddy rich zone in the northwest pacific ocean analyses of satellite altimetry and the best track data from the joint typhoon warning center show that during the 36 h of the maemi eddy encounter maemi s intensity in 1 min sustained wind shot up from 41 ms 1 to its peak of 77 m s 1 maemi subsequently devastated the southern korean peninsula based on results from the coupled hurricane intensity prediction system and satellite microwave sea surface temperature observations it is suggested that the warm eddies act as an effective insulator between typhoons and the deeper ocean cold water the typhoon s self induced sea surface temperature cooling is suppressed owing to the presence of the thicker upper ocean mixed layer in the warm eddy which prevents the deeper cold water from being entrained into the upper ocean mixed layer as simulated using the coupled hurricane intensity prediction system the incorporation of the eddy information yields an evident improvement on maemi s intensity evolution with its peak intensity increased by one category and maintained at category 5 strength for a longer period 36 h of time without the presence of the warm ocean eddy the intensification is less rapid this study can serve as a starting point in the largely speculative and unexplored field of typhoon warm ocean eddy interaction in the western north pacific given the abundance of ocean eddies and intense typhoons in the western north pacific these results highlight the importance of a systematic and in depth investigation of the interaction between typhoons and western north pacific eddies

three trench endings in eastern indonesia abstract underway surveys using long range sidescan sonar as well as conventional marine geophysical techniques have been made of three trench endings in eastern indonesia in each case the termination is associated with the presence of a block of thickened crust the transition between the sunda trench and the troughs which encircle the banda arc is a consequence of collision with the northern margin of the australian continent whereas the southern termination of the philippine trench is defined by the presence of an oceanic plateau which impedes further southwards propagation both these trenches are currently active and are associated with clearly defined wadati benioff zones the new guinea trench terminates in the west at a n trending seafloor rise known as the mapia ridge the relationship between the two features is not well understood there are no clear indications of present day subduction along the northern margin of new guinea and insufficient data from the flanks of the mapia ridge to show whether this ever had a subduction history the new data obtained within the trench immediately east of the ridge suggests that subduction has ceased in the westernmost part of the new guinea trench and that the oceanic crust of the ayu basin west of the mapia ridge post dates the period of active subduction

plate boundary evolution in the halmahera region indonesia abstract halmahera is situated in eastern indonesia at the southwest corner of the philippine sea plate active arc arc collision is in process in the molucca sea to the west of halmahera new stratigraphic observations from halmahera link this island and the east philippines and record the history of subduction of the molucca sea lithosphere the halmahera basement complex and the basement of east mindanao were part of an arc and forearc of late cretaceous early tertiary age and have formed part of a single plate since the late eocene early oligocene there is no evidence that halmahera formed part of an oligo miocene arc but arc volcanism associated with eastwards subduction of the molucca sea beneath halmahera began in the pliocene and the pliocene arc is built on a basement of the early tertiary arc arc volcanism ceased briefly during the pleistocene and the arc shifted westwards after an episode of deformation the present active arc is built upon deformed rocks of the pliocene arc the combination of new stratigraphic information from the halmahera islands and models of the present day tectonic structure of the region deduced from seismic and other geophysical studies is used to constrain the tectonic evolution of the region since the miocene diachronous collision at the western edge of the philippine sea plate which began in mindanao in the late miocene impeded the movement of the philippine sea plate and further motion has been achieved by a combination of strike slip motion along the philippine fault subduction at the philippine trench and subduction of the molucca sea lithosphere beneath halmahera

westward motion of mesoscale eddies abstract since the pioneering work of nof the determination of the westward drift of mesoscale eddies under the planetary beta effect has been a recurrent theme in mesoscale oceanography and several different formulae have been proposed in the literature here recpatiulation is sought and within the confines of a single layer model a generalized formula is derived although it is similar to nof s the present formula is established from a modified definition and with fewer assumptions it also recaptiulates all other formulae for the one layer model and applies to a wide variety of situations including cases when the vortex develops a wake of rossby waves or undergoes axismmetrization following the derivation of the formula a physical interpretation clarifies the migration mechanism which can be divided between a self induced propulsion and a reaction from the displaced ambient fluid numerical simulations with primitive and geostrophic equations validate the formula for a variety of length sc

seasonal to interannual variations in the intensity and central position of the surface kuroshio east of taiwan 1 seasonal and interannual changes of surface kuroshio intensity and central position east of taiwan during 1993 2012 are investigated by quantitatively analyzing the satellite altimetry product the kuroshio moves inshore offshore off northeast of taiwan in winter summer whereas it has an offshore inshore path off southeast of taiwan in winter summer the seasonal change of heat flux over the east china sea shelf is found to cause the seasonality of the kuroshio central position off northeast of taiwan whereas the seasonal kuroshio movement off southeast of taiwan is found to be induced by the combined effect of the kuroshio changes through the luzon strait and the eastern luzon island in contrast to this y dependent path changes the kuroshio becomes weaker stronger as a whole east of taiwan in winter summer on the interannual time scales the kuroshio throughout the eastern coast of taiwan intensifies and has a concurrent offshore path during the periods of 1995 1997 and 2004 2007 the relative intensity of cyclonic eddies to anticyclonic eddies off eastern taiwan are found to contribute to these interannual kuroshio changes

basement rocks of the halmahera region eastern indonesia a late cretaceous early tertiary arc and fore arc halmahera is a k shaped island located at the junction of several major arc trench systems of the western pacific eastern indonesia region western halmahera is an active volcanic arc above a zone of intense seismicity which characterizes the north molucca sea eastern halmahera has a basement of dismembered ophiolitic rocks with slices of mesozoic and eocene sediments overlain unconformably by middle oligocene and younger sedimentary and volcanic rocks the mesozoic and eocene sediments reveal notable stratigraphical and petrological similarities to the marianas fore arc and the eastern halmahera basement complex is interpreted as a pre oligocene fore arc lacking an accretionary complex there is some evidence that the pre oligocene volcanic arc behind this fore arc now forms part of the basement of western halmahera the mesozoic and tertiary sediments were imbricated together with igneous and metamorphic rocks representing the deeper parts of the fore arc during the late eocene plate reorganization event recognized throughout the western pacific margins the eastern halmahera basement complex can be traced into eastern mindanao probably further northwards in the eastern philippines and may be related to similar terranes within and around the present philippine sea plate in contrast the southern part of the island of bacan at the southwestern end of the halmahera group has a basement of continental metamorphic rocks associated with a deformed ophiolitic complex quite different to the basement of eastern halmahera the metamorphic rocks are interpreted to be part of the north australian continental margin basement which is separated from the halmahera basement complex by a splay of the sorong fault system and the deformed ophiolite complex of bacan is suggested to represent magmatism in the fault zone

modulation of kuroshio transport by mesoscale eddies at the luzon strait entrance measurements of kuroshio current velocity at the entrance to luzon strait along 18 75 n were made with an array of six moorings during june 2012 to june 2013 strong positive relative vorticity of the order of the planetary vorticity f was observed on the western flank of the kuroshio in the upper 150 m on the eastern flank the negative vorticity observed was about an order of magnitude smaller than f kuroshio transport near its origin is computed from direct measurements for the first time kuroshio transport has an annual mean of 15 sv with a standard deviation of 3 sv it is modulated strongly by impinging westward propagating eddies which are identified by an improved eddy detection method and tracked back to the interior ocean eight kuroshio transport anomalies 5 sv are identified seven are explained by the westward propagating eddies cyclonic anticyclonic eddies decrease increase the zonal sea level anomaly sla slope and reduce enhance kuroshio transport large transport anomalies of 10 sv within o 10 days are associated with the pairs of cyclonic and anticyclonic eddies the observed kuroshio transport was strongly correlated with the sla slope correlation 0 9 analysis of sla slope data at the entrance to luzon strait over the period 1992 2013 reveals a seasonal cycle with a positive anomaly i e an enhanced kuroshio transport in winter and spring and a negative anomaly in summer and fall eddy induced vorticity near the kuroshio has a similar seasonal cycle suggesting that seasonal variation of the kuroshio transport near its origin is modulated by the seasonal variation of the impinging mesoscale eddies

the kuroshio east of taiwan moored transport observations from the woce pcm 1 array observations from the woce pcm 1 moored current meter array east of taiwan for the period september 1994 to may 1996 are used to derive estimates of the kuroshio transport at the entrance to the east china sea three different methods of calculating the kuroshio transport are employed and compared these methods include 1 a direct method that uses conventional interpolation of the measured currents and extrapolation to the surface and bottom to estimate the current structure 2 a dynamic height method in which moored temperature measurements from moorings on opposite sides of the channel are used to estimate dynamic height differences across the current and spatially averaged baroclinic transport profiles and 3 an adjusted geostrophic method in which all moored temperature measurements within the array are used to estimate a relative geostrophic velocity field that is referenced and adjusted by the available direct current measurements the first two methods are largely independent and are shown to produce very similar transport results the latter two methods are particularly useful in situations where direct current measurements may have marginal resolution for accurate transport estimates these methods should be generally applicable in other settings and illustrate the benefits of including a dynamic height measuring capability as a backup for conventional direct transport calculations the mean transport of the kuroshio over the 20 month duration of the experiment ranges from 20 7 to 22 1 sv 1 sv 106 m3 s 1 for the three methods or within 1 3 sv of each other the overall mean transport for the kuroshio is estimated to be 21 5 sv with an uncertainty of 2 5 sv all methods show a similar range of variability of 10 sv with dominant timescales of several months fluctuations in the transport are shown to have a robust vertical structure with over 90 of the transport variance explained by a single vertical mode the moored transports are used to determine the relationship between kuroshio transport and sea level difference between taiwan and the southern ryukyu islands allowing for long term monitoring of the kuroshio inflow to the east china sea

genesis of a gulf of mexico ring as determined from kinematic analyses the kinematics of the loop current are studied using trajectories of drifters in the gulf of mexico during mid june through september 1985 one of the drifters was in the loop current proper while other drifters were in two recently shed loop current rings the drifter in the loop current showed strong anticyclonic motion during the study period this loop current anticyclone first began off the northwest coast of cuba it rapidly moved northward into the gulf of mexico as a ring pinched off from the loop current analysis of the loop current drifter motion showed that the anticyclone became an integral part of the loop current taking on many of the characteristics of the most recently shed ring the results of the analysis suggest a process by which loop current rings can be generated apparently this mechanism can cause the loop current to become reconfigured in 2 3 months for beginning the process of ring separation

eddy characteristics in the eastern south pacific 1 the main eddy characteristics length scales rotation period swirl and translation velocities are determined in the eastern south pacific region 10 35 s and 70 100 w based on surface drifter measurements satellite altimetry and hydrographic data from the woce p19 section the chile peru current eddies have a typical diameter of order of 30 km smaller than the typical rossby radii observed in the region they are principally formed near the south american coast and propagate seaward with a translation velocity varying from 3 cm s 1 in the southern part of the study domain to 6 cm s 1 north of 15 s long lived anticyclonic eddies propagate northwestward with a mean angle of around 333 t whereas cyclonic vortices propagate westward consistent with the vortices propagation theory on a plane the radial distribution of the swirl velocity shows that the chile peru current eddies have a maximum diameter of order 200 km with a swirl velocity of around 14 cm s 1 and a rotation period of 50 days hydrographic data reveal a vertical extent down to around 2000 m for energetic eddies no significant difference is observed between the tangential velocities of cyclonic and anticyclonic eddies geostrophic balance can be considered for large radii whereas ageostrophic dynamics may play an important role near the eddy centers

interannual modulation of the pacific decadal oscillation pdo on the low latitude western north pacific to investigate the interannual variability in the northwestern pacific an empirical mode decomposition emd was applied to 17 year absolute dynamic topography adt data west of luzon island the philippines the mean sea surface height in this area is an appropriate index for the kuroshio intrusion into the south china sea scs significant interannual fluctuations were extracted by the emd the interannual variability was strongly correlated with the pacific decadal oscillation pdo index but not the el nino southern oscillation enso this indicated the potential impact of the pdo on the circulation in the area in the warm phase of the pdo positive index a southerly anomalous wind off the philippines causes a northward shift of the north equatorial current bifurcation latitude necbl this leads to a weakened kuroshio off luzon favoring kuroshio intrusion into the scs the northward migration of the necbl also results in a weakened kuroshio off southeast taiwan and a larger kuroshio transport off northeast taiwan the abundant westward propagating eddies impinging on the kuroshio in the subtropical countercurrent region increases this transport although the enso has little effect on monsoonal winds during the warm pdo phase it has a strong impact on the monsoon and meridional migration of the necbl during the cold phase of the pdo therefore necbl variations only show a close correspondence with the enso during the cold pdo phase because the influence of the enso is not stationary the impact of the pdo should be taken into account when examining interannual variability in the low latitude western north pacific

lithospheric deformation within the molucca sea arc arc collision evidence from shallow and intermediate earthquake activity this paper presents the results of a local earthquake survey in the molucca sea arc arc collision zone of eastern indonesia although intermediate depth earthquakes define zones dipping to the west beneath the sangihe arc and to the east beneath the halmahera volcanic arc only shallow activity less than 60 km depth occurred beneath the central part of the collision zone where the majority of activity is observed the concentration of earthquake foci in the 10 to 50 km depth range in a limited region beneath the talaud mayu ridge suggests that convergence between the arcs proceeds by shortening within basement of the intervening molucca sea plate rather than by slip along shallow dipping planes between the arcs and the subducted slabs published focal mechanism solutions suggest that high angle reverse faulting beneath the talaud mayu ridge generates almost all of the seismic energy release within the collision zone the predominance of shallow reverse and strike slip faulting at the axis of the bilaterally subducting molucca sea lithosphere suggests that stresses are not due to bending alone and have a large horizontal regional component perpendicular to the island arcs the geometry and state of stress within the molucca sea lithosphere requires an external driving force for the convergence between the two arcs and a strong degree of coupling between the island arcs and the subducting molucca sea plate at least at the present stage of collision

kinematic pile response to vertical p wave seismic excitation an analytical solution based on a rod on dynamic winkler foundation model is developed for the response of piles in a soil layer subjected to vertical seismic excitation consisting of harmonic compressional waves closed form solutions are derived for 1 the motion of the pile head 2 the peak normal strain in the pile and 3 the group effect between neighboring piles the solutions are expressed in terms of a dimensionless kinematic response factor iv relating pile head motion and free field soil surface motion a dimensionless strain transmissibility factor ie relating pile and soil peak normal strains and a pile to pile interaction factor measuring group effects it is shown that a pile foundation may significantly reduce the vertical seismic excitation transmitted to the base of a structure

active tectonics of the eastern sunda and banda arcs the tectonics of the eastern sunda and banda arcs of eastern indonesia are inferred from the centroid depths seismic moments and fault plane solutions of 63 large earthquakes that occurred between 1962 and 1984 source parameters are estimated by inverting long period teleseismic p and sh waves earthquakes show that the collision of the australian continent with the banda arc shortens the upper plate beneath the forearc and back arc basin over the broad area between the timor and seram troughs along the eastern end of the sunda arc and along the southern banda arc earthquakes reveal that the arc and forearc respond to collision by shortening in the direction of convergence by elongating in the direction perpendicular to convergence and by thrusting over the back arc basin shallow thrust and strike slip earthquakes beneath the banda basin the back arc basin demonstrate that deformation within the back arc accommodates some of the northward motion of the australian continent the rate of north south shortening of the entire upper plate at the longitude of timor calculated from the seismic moments of the earthquakes over the 22 year period is roughly 20 of the predicted convergence rate between australia and southeast asia strike slip faulting within the banda basin results also in eastward motion of the banda arc with respect to western indonesia and australia eastward extrusion of the banda arc results in thrusting at the aru trough earthquakes due to thrusting of the back arc basin beneath the volcanic arc are too shallow to corroborate that the arc s polarity has reversed although the wetar back arc thrust zone at present has a high seismic slip rate earthquakes and their mechanisms provide evidence that the lithosphere of the weber basin a 7500 m deep forearc basin rests on the subducting lithosphere without intervening asthenosphere so that the weber basin subsides in response to sinking of the subducting lithosphere closure of the banda basin is geometrically incompatible with the australian plate subducting simultaneously beneath both the timor and seram troughs instead the bird s head which subducts beneath seram is decoupled from the australian plate in western new guinea and probably moves west or southwest with respect to australia in the eastern indonesian example strike slip faulting plays a major role in the evolution of the collision zone and clearly demonstrates the complexity in three dimensions of continental accretion and mountain building by arc continent collision

effects of kuroshio intrusions on the atmosphere northeast of taiwan island the kuroshio loses bathymetric support off northeast taiwan island causing large variability in its path the resultant covariability of sea surface temperature sst and the lower atmosphere is investigated using satellite observations in winter and spring off northeast taiwan island the intrusions of warm kuroshio water onto the continental shelf cause a large increase in local sst intensify the northeasterly monsoonal winds and lead to the increases in water vapor and rainfall key to this air sea interaction is the existence of anomalous heat advection by the kuroshio intrusions the kuroshio intrusions are partly due to westward propagating ocean eddies east of taiwan island with a lead time of 3 weeks hinting at the possibility of improved weather prediction near northeast taiwan island by considering ocean variability east of taiwan island

eddy development and motion in the caribbean sea eddy motion in the caribbean sea is described on the basis of sea level anomalies deduced from ers 1 altimetry data corrected with topex poseidon data during the 15 months of the exact repeat mission october 1992 to december 1993 both cyclones and anticyclones were observed in the satellite data as anomalies originating in the venezuelan basin or entering the caribbean through the antillean passages mainly the st lucia channel anegada passage and north of trinidad the diameter of the eddies ranged from a few tens of kilometers to 700 km advection speeds were typically 20 30 cm s 1 and the eddies were energetic kinetic energy 0 6 m2 s 2 their lifetime of 3 4 months was determined in general by their interaction with topography most eddy activity was eroded and disappeared at the central american rise area although a few eddies crossed into the cayman sea through the chibcha channel some eddies also entered the cayman sea from outside the caribbean through the windward passage the panama colombia gyre was evident only during the tropical rainy season a large cyclonic eddy was formed there during the period of maximum precipitation when strong meridional salinity and wind speed gradients occurred eddy production in the central caribbean appears to be associated with the interaction of the meandering caribbean current and the strong wind curl

mesoscale eddies in the south china sea mean properties spatiotemporal variability and impact on thermohaline structure we investigated mean properties and the spatiotemporal variability of eddies in the south china sea scs by analyzing more than 7000 eddies corresponding to 827 eddy tracks identified using the winding angle method and 17 years of satellite altimetry data eddies are mainly generated in a northeast southwest direction and southwest of luzon strait there is no significant difference between the numbers of two types of eddies anticyclonic and cyclonic in most regions the mean radius and lifetime of eddies are 132 km and 8 8 weeks respectively both depending on where the eddies are formed anticyclonic and cyclonic eddies tend to deform during their lifetimes in different ways furthermore eddy propagation and evolution characteristics are examined in the northern scs eddies mainly propagate southwestward along the continental slope with velocities of 5 0 9 0 cm s 1 while in the central scs eddies tend to move with slight divergence but still in a quasi westward direction with velocities of 2 0 6 4 cm s 1 eddy propagation in the western basin to the east of vietnam is quite random with no uniform propagate direction investigation of 38 long lived eddies shows that eddies have a swift growing phase during the first 12 weeks and then a slow decaying phase that affects the eddy radii and eddy energy densities nevertheless vorticity has less variability in addition the effect of eddies on the thermocline and halocline is analyzed using 763 argo temperature profile data cyclonic eddies drive the thermocline shallower and thinner and significantly strengthen the thermocline intensity whereas anticyclonic eddies cause the thermocline to deepen and thicken and weaken the thermocline intensity to a certain degree the halocline impacted by cyclonic eddies is also shallower and thinner than that impacted by anticyclonic eddies finally eddy temporal variations are examined at seasonal and interannual scales eddy activity is sensitive to the wind stress curl and in the northern scs it is also related with the strength of the background flows

potential vorticity balances and horizontal divergence along particle trajectories in gulf stream meanders east of cape hatteras abstract trajectories of 37 isopycnal rafos floats launched in the gulf stream off cape hatteras have been analyzed to examine the dynamics of meanders from a lagrangian viewpoint using the float data in conjunction with information on the structure of horizontal velocity shear from the pegasus study halkin and rossby variations in planetary curvature and shear vorticity have been estimated along the float trajectories changes in fluid layer thickness were then inferred assuming potential vorticity is conserved following the floats this analysis shows that curvature vorticity changes are typically 10 20 of f planetary vorticity as fluid parcels travel between meander troughs and crests lateral shear changes on the order of 20 30 of f are common as parcels move laterally relative to the jet axis between meander extrema although changes in these two terms are usually of opposite sign and tend to compensate significant layer thickness changes do occur with some parcels exhibiting 30 change

eddy transport of heat and thermocline waters in the north pacific a key to interannual decadal climate variability abstract high resolution xbt transects in the north pacific ocean at an average latitude of 22 n are analyzed together with topex poseidon altimetric data to determine the structure and transport characteristics of the mesoscale eddy field based on anomalies in dynamic height 410 eddies are identified in 30 transects from 1991 to 1999 including eddies seen in multiple transects over a year or longer their wavelength is typically 500 km with peak to trough temperature difference of 2 2 c in the center of the thermocline the features slant westward with decreasing depth by 0 8 of longitude on average from 400 m up to the sea surface this tilt produces a depth varying velocity temperature correlation and hence a vertical meridional overturning circulation in the mean 3 9 sv sv 106 m3 s 1 of thermocline waters are carried southward by the eddy field over the width of the basin balanced mainly by northward flow in the surface layer corresponding northward heat transport is 0 086 0 012 pw

structure of an eddy measured with drifters drifters are used to measure the structure of an eddy on western bank scotian shelf over a 5 day period a regression method that uses both the temporal and spatial structure of flow field observations is presented and used to analyze this eddy the eddy has vorticity 1 9 10 5 s 1 with divergence stretching deformation and shearing deformation smaller by more than an order of magnitude the eddy is centered on the crest of western bank the motion residual to the eddy had a slab like part that moved all points on a plane in a circle without rotation this latter type of motion can cause substantial error when vorticity and other eddy properties are estimated using methods that operate on a single drifter track the eulerian statistics of residual motion show correlations greater than 0 5 are restricted to spatial separations less than 2 km and temporal lags less than 3 h but motion directed along the vector separating two velocity measurements has a significant eulerian correlation for timescales of more than 40 hours and length scales of order 5 km transverse motion is positively correlated over lesser scales much cluster distortion results from subtidal frequency motion that has spatial scales that are seldom coherent over drifter separation scales greater than 2 3 km the long lagrangian timescale is inconsistent with a description of horizontal mixing in terms of an eddy diffusion coefficient rather we might picture drifters being dispersed by slowly evolving narrow streams of current that have larger spatial scales along their axis than across their axis

three dimensional oceanic eddy analysis in the southern california bight from a numerical product with eight islands complex coastlines and bottom topography strong wind curls and frequent upwelling fronts the southern california bight scb is an area with strong eddy activity by applying an automated eddy detection scheme to a 12 year high resolution numerical product of the oceanic circulation in the scb a three dimensional eddy data set is developed it includes information for each eddy s location polarity intensity size boundary and moving path at nine vertical levels through a series of statistical analyses applied to the eddy data set three dimensional statistical characteristics of mesoscale and submeoscale eddy variations in the scb are elucidated these shed light on how eddies are generated evolve and terminate a significant percentage of eddies is found to be generated around islands and headlands along the coastline which indicates that islands in the scb play a vital role in eddy generation three types of eddies based on shape are identified from the numerical product bowl lens and cone a dynamic analysis shows that some submesoscale eddies with finite local rossby numbers tend to be ageostrophic balanced while mesoscale eddies are in geostrophic balance the present research results are useful for the interpretation of data sets obtained during the interdisciplinary santa barbara channel radiance in a dynamic ocean radyo field experiment conducted on september 3 25 2008