reconstructability of three dimensional upper ocean circulation from swot sea surface height measurements abstractutilizing the framework of effective surface quasigeostrophic esqg theory this study explores the potential of reconstructing the 3d upper ocean circulation structures including the balanced vertical velocity w field from high resolution sea surface height ssh data of the planned surface water and ocean topography swot satellite mission specifically the authors utilize the 1 30 submesoscale resolving ofes model output and subject it to the swot simulator that generates the along swath ssh data with expected measurement errors focusing on the kuroshio extension region in the north pacific where regional rossby numbers range from 0 22 to 0 32 this study finds that the esqg dynamics constitute an effective framework for reconstructing the 3d upper ocean circulation field using the modeled ssh data as input the esqg reconstructed relative vorticity and w fields are found to reach a correlation of 0 7 0 9 and 0 6 0 7 respectively in the 1000 m upper ocean when compared to the orig

dynamics of eddy motions in the eastern north atlantic abstract the behavior of the intense anticyclonic eddy observed during the tourbillon experiment september november 1979 is studied within the framework of quasi geostrophic dynamics the nondivergent part of the pressure held is estimated through objective analysis at the times of four quasi synoptic ctd arrays making use as well of velocity data from the current meter mooring array and subsurface acoustic floats maps of relative vorticity vortex stretching and potential vorticity allow identification of the signature of the eddy nearby companion anomalies caused by an intrusion of mediterranean water mw can be singled out and are comparable to those of the main eddy around 1200 m eulerian and lagrangian tests of the conservation of potential vorticity are presented and the close similarities of salinity and potential vorticity as tracers of mesoscale motions are vividly demonstrated computations of advection of vortex stretching and relative vorticity show that the anticyclonic path of the mai

late triassic granites from bangka indonesia a continuation of the main range granite province of the south east asian tin belt the south east asian tin belt is one of the most tin productive regions in the world it comprises three north south oriented granite provinces of which the arc related eastern granite province and the collision related main range granite province run across thailand singapore and indonesia these tin producing granite provinces with different mineral assemblages are separated by paleo tethyan sutures exposed in thailand and malaysia the eastern province is usually characterised by granites with biotite hornblende main range granites are sometimes characterised by the presence of biotite muscovite however the physical boundary between the two types of granite is not well defined on the indonesian tin islands because the paleo tethyan suture is not exposed on land there both hornblende bearing previously interpreted as i type and hornblende barren previously interpreted as s type granites are apparently randomly distributed on the indonesian tin islands granites exposed on bangka the largest and southernmost tin island no matter whether they are hornblende bearing or hornblende barren are geochemically similar to malaysian main range granites the average epsilon nd t value obtained from the granites from bangka average epsilon nd t 8 2 falls within the range of the main range province 9 6 to 5 4 these granites have sims zircon u pb ages of ca 225 ma and ca 220 ma respectively that are both within the period of main range magmatism similar to 226 201 ma in the peninsular malaysia we suggest that the granites exposed on bangka represent the continuation of the main range province and that the paleo tethyan suture lies to the east of the island

u pb zircon dating of granitoid plutons from the west coast province of peninsular malaysia u pb zircon dating of granitoid plutons from the west coast province of peninsular malaysia yields precise and unambiguous ages of 198 220 ma late triassic these ages are considerably older than previously reported k ar mica ages which have been largely reset but agree with or are younger than rb sr whole rock apparent ages the u pb zircon ages are considered to represent the best estimate of the intrusive ages of the plutons some of the problems associated with the interpretations of the pre triassic rb sr whole rock apparent ages are discussed here and alternative ways to explain these ages in the light of recent work are considered reversely discordant patterns displayed by zircon populations from a number of plutons yield consistent upper intersection ages of 1500 1700 ma that approximately date source derived inherited zircon components the precambrian ages of these inherited zircon components suggest that the west coast province s type granitoids are derived from sedimentary sources recycled at least in part from mid proterozoic crystalline basement sources

seasonal mesoscale and submesoscale eddy variability along the north pacific subtropical countercurrent abstractlocated at the center of the western north pacific subtropical gyre the subtropical countercurrent stcc is not only abundant in mesoscale eddies but also exhibits prominent submesoscale eddy features output from a high resolution ogcm simulation and a gridded satellite altimetry product are analyzed to contrast the seasonal stcc variability in the mesoscale versus submesoscale ranges resolving the eddy scales of 150 km the altimetry product reveals that the stcc eddy kinetic energy and rms vorticity have a seasonal maximum in may and april respectively a weak positive vorticity skewness without seasonal dependence and an inverse forward kinetic energy cascade for wavelengths larger shorter than 250 km in contrast the submesoscale resolving ogcm simulation detects that the stcc eddy kinetic energy and rms vorticity both appear in march a large positive vorticity skewness with strong seasonality and an intense inverse kinetic energy cascade whose short wave cutoff migrates seaso

deep to shallow marine sedimentology and impact of volcanism within the middle triassic palaeo tethyan semantan basin singapore abstract the middle triassic pulau ayer chawan formation is a predominantly deep marine occasionally shallow marine sedimentary succession deposited in the singapore sector of the palaeo tethyan semantan basin the formation provides an important record of the dynamic interplay between a siliciclastic sedimentary system and the products of an adjacent active volcanic arc it is characterised by six sub environments including deep marine turbidite fan deep marine background sedimentation subaqueous debris cone shallow marine volcanically sourced turbidite fan and hyaloclastite mound or ridge turbidite fan deposits preserve the input of both siliciclastic and volcaniclastic sediments from the shelf transported into the deep marine environment by a suite of subaqueous sediment gravity flow processes including turbidity currents mixed flow types hybrid event beds concentrated and hyper concentrated sediment gravity flows and debris flows thick heterolithic successions of debrites were likely sourced through regular collapse of an unstable shelf the presence of hybrid event beds encountered within the deep marine turbidite fans supports a slope that was out of grade and may have been actively retreating towards the hinterland together these factors suggest regional scale uplift of the eastern margins of the semantan basin during triassic times most likely facilitated through volcanic activity in the adjacent palaeo tethys sukhothai arc evidence for contemporaneous arc related magmatism includes ubiquitous volcaniclastic sedimentary rocks within formation including pyroclastic density current deposits and perhaps more strikingly through the hyaloclastites of the nanyang member the hyaloclastites formed through quenching of magmas delivered into the deep marine setting from a series of sub sea vents or mounds

triassic radiolarian faunas from the mae sariang area northern thailand and their paleogeographic significane abstract early to late triassic spathian to carnian radiolarians were obtained from the bedded chert sequence of the mae sariang group distributed in northern thailand based on the similarity of radiolarian fauna and petrographical characteristics it is inferred that the fine grained siliceous and calcareous sediments of the mae sariang group are equivalent to those belonging to the eastern marginal facies of the sibumasu block moreover the occurrence of an early carnian radiolarian assemblage from bedded chert shows that the closure of the paleotethys ocean between the sibumasu and indochina blocks in northern thailand occurred after the early carnian

intensive surveys of the azores front 2 inferring the geostrophic and vertical velocity fields the geostrophic and vertical velocity fields are inferred using density and horizontal velocity data from three seasoar acoustic doppler current profiler surveys of the azores front the analysis is a two step procedure consisting of 1 objective analyses to reflect the observed length scales and 2 dynamical adjustments so that the density field is statically stable and the velocity field is in geostrophic balance the vertical velocity is inferred using a version of the quasi geostrophic omega equation in which the stratification is allowed to vary in the horizontal the resulting vertical velocity peaks at 2 10 4 m s 1 at 200 300 m there is a tendency for the denser water to the north of the front to be downwelled while the warmer water to the south is upwelled the implied heat flux exceeds 10 w m 2 near 100 m depth so the upper 100 m is warmed while the lower water column is cooled tending to stratify the upper ocean ageostrophic horizontal flow is toward the dense side of the front at the surface the dominant terms in the density balance are time rate of change and horizontal advection the inferred circulation cells may be an important mechanism of subduction in the upper ocean

diagnosis of vertical velocities in the upper ocean from high resolution sea surface height 1 a surface quasi geostrophy based esqg method to diagnose the vertical velocity field from sea surface height ssh is assessed using high resolution simulations these simulations concern a turbulent eddy field with large rossby numbers and energetic wind driven motions results indicate that low frequency vertical velocities and also horizontal motions can be reconstructed within a range of scales between 20 km and 400 km from the surface down to 500 m the only information needed is a single high resolution ssh snapshot and information on the large scale vertical stratification inertial motions are naturally filtered because they do not contaminate ssh as we demonstrate these results are encouraging and further strengthen previous studies using the esqg method they indicate that access to high resolution ssh may represent a major advance to retrieve horizontal and vertical fluxes of any tracer in the upper ocean

reconstructing the ocean interior from high resolution sea surface information abstractwhen evaluated against the 1 30 resolution submesoscale resolving ofes model outputs the previously published interior surface quasigeostrophic method from the 2013 study by wang et

reconstructing upper ocean vertical velocity field from sea surface height in the presence of unbalanced motion abstractreconstructability of upper ocean vertical velocity w and vorticity fields from high resolution sea surface height ssh data is explored using the global 1 48 horizontal resolution mitg

global ocean current reconstruction from altimetric and microwave sst measurements ocean currents are a key component to understanding many oceanic and climatic phenomena and knowledge of them is crucial for both navigation and operational applications currently they are derived from sea surface height ssh measurements provided by altimeters however distances between tracks and the limited number of available altimeters lead to errors in the accurate location of oceanic currents in this study we investigate the capability of sea surface temperature sst observations to reconstruct surface currents at a global scale the methodology we use consists of estimating the stream function by taking the phase from sst and the spectrum of ssh and then comparing it with altimetric measurements results reveal that sst provided by microwave radiometers can be used to retrieve ocean currents during winter near the major extratropical current systems which are characterized by an intense mesoscale activity and the presence of strong thermal gradients we have also found that surface ocean current reconstruction based on surface quasi geostrophic approach can be improved if the information about the energy spectrum provided by altimeters is used this points to the development of a new method of reconstructing ocean currents based on the combination of the phase of sst images with the energy spectrum derived from along track altimetric measurements

observation of near inertial wave reflections within the thermostad layer of an anticyclonic mesoscale eddy 1 moored current observations in the southwestern east japan sea of 16 5 months duration clearly captured two episodes of downward phase propagation upward energy propagation of near inertial waves niws time series of temperature and velocity from the mooring and ancillary information indicate that the mooring was located near the center of an anticyclonic eddy during these events considering the typical vertical structure of quasi permanent eddy features in the region the observed downward phase propagation appeared to occur within the seasonal thermocline and upper thermostad of the anticyclonic mesoscale eddy ray tracing simulation of niw using the observed subinertial currents suggests that the upward energy propagation is caused by the reflection of the niws within the thermostad of the anticyclonic eddy where the effect of the vertical shear of subinertial horizontal currents is larger than the buoyancy effect in controlling the propagation of niws

ductile and brittle deformation in singapore a record of mesozoic orogeny and amalgamation in sundaland and of post orogenic faulting abstract singapore bedrock geology is dominated by late permian to triassic arc magmatism and a genetically related essentially middle to upper triassic marine to fluvial volcano sedimentary inner forearc succession these mesozoic strata are deformed into a pattern of ne translated ductile brittle deformation structures during the latest triassic to earliest jurassic collision and amalgamation of the sibumasu continental block with the southern part of the sukhothai arc the subduction related magmatic complex represented in singapore by the granitic to gabbroic plutons of the bukit timah centre likely acted as a backstop to thrusting at this time collisional tectonics drove progressive shortening and steepened earlier formed inclined asymmetrical folds culminating in the regional scale development of a non coaxial ne vergent and ne facing fold and thrust system in singapore the murai thrust and pasir laba thrust are identified as major elements of this system both are associated with sw dipping thrust imbricate duplex slices two distinct early cretaceous berriasian and barremian sedimentary successions overstep these collisional tectonic structures an array of mostly ne sw and ene wsw trending faults and fractures acts as an important control on bedrock unit distribution across singapore and are most likely generated by cenomanian dextral shear stress that stress locally reactivated faults initiated during orogeny or even earlier knowledge of the geotechnical impact of these structural features is critical to both future development and ongoing management of the subsurface in singapore

net primary production in the gulf stream sustained by quasi geostrophic vertical exchanges we analyze 12 years of mesoscale vertical motion derived from an observation based product in the top 1000 m of the north west atlantic ocean vertical velocities o 10 m d 1 associated with gulf stream instabilities consist of alternating cells of upwelling and downwelling here we show that the magnitude of the vertical motions decays exponentially southward with an e folding length scale that is informative on the dynamics of the system we further investigate the impact of the vertical supply of nutrients about phytoplankton growth with a conceptual model incorporating the mean effect of nutrient distribution quasi geostrophic dynamics and ekman suction pumping results confirm that the mean effect of mesoscale vertical velocity variability alone can sustain observed levels of net primary production in the immediate vicinity of the gulf stream while other mechanisms including horizontal advection and submesoscale dynamics need to be considered when moving toward the subtropical gyre

enhanced vertical propagation of storm induced near inertial energy in an eddying ocean channel model the interaction between inertial oscillations generated by a storm and a mesoscale eddy field is studied using a southern ocean channel model it is shown that the leakage of near inertial energy out of the surface layer is strongly enhanced by the presence of the eddies with the anticyclonic eddies acting as a conduit to the deep ocean given the ubiquity of the atmospheric storm tracks a source of near inertial energy for the ocean and regions of strong ocean mesoscale variability we argue that this effect could be important for understanding pathways by which near inertial energy enters the ocean and is ultimately available for mixing

mineralogical and geochemical imprints to determine the provenance depositional history and tectonic settings of triassic turbidites in the semanggol and semantan basins peninsular malaysia abstract the present study provides systematic mineralogical inorganic geochemical and rock eval analyses of turbidite deposits of the semanggol and semantan formations to investigate their provenance depositional environment and tectonic setting as well as type origin and maturation of organic matter in black shale these deposits are extensively distributed in peninsular malaysia and are observed in the field as conglomerate pebbly sandstone thick bedded sandstone interbedded sandstone and shale laminated black shale and tuffaceous sandstone these sedimentary sequences are predominantly deep marine and occasional shallow marine deposits characterizing a deep marine fan system based on al2o3 tio2 ratios more felsic rocks for the semanggol formation and felsic intermediate rocks for the semantan formation are proposed as sources for their detrital fractions and this interpretation is also substantiated by the binary plot of zr vs ti v v ni v ni and ni co analyses indicate anoxic oxic conditions ternary diagram of immobile trace elements inferred passive margin for semanggol turbidites and an active continental margin for semantan turbidites the dissimilarity between geochemically and geologically derived tectonic settings mainly for the semanggol turbidites is because of changing tectonic setting and recycled nature of sediment sources that were deposited in diverse tectonic settings the black shale clay fractions from both formations dominantly contain illite and kaolininte with abundant traces of quartz the illite content varies from 43 to 56 and illite crystallinity index ic from 0 2 to 0 4 2 average 0 28 2 showing studied black shale fall in anchizone rock eval pyrolysis reveals type iii kerogens suggesting a terrestrial source of organic matter in black shale of both formations

variability of the kuroshio extension jet recirculation gyre and mesoscale eddies on decadal time scales abstract twelve years of sea surface height ssh data from multiple satellite altimeters are used to investigate the low frequency changes and the interconnections of the kuroshio extension ke jet its southern recirculation gyre and their mesoscale eddy field the dominant signal is characterized by the steady weakening of the ke jet recirculation gyre from 1993 to 1996 followed by a gradual strengthening after 1997 during the weakening period of 1993 96 the ke path migrated southward in general and this path migration reversed in direction during the strengthening period of the ke jet and recirculation gyre after 1997 by hindcasting the ssh signals using linear vorticity dynamics it was found that weakening strengthening in the ke jet and recirculation gyre is consistent with westward propagation of negative positive ssh anomalies generating in the eastern north pacific and strengthening during their westward propagation when the ke jet and recirculation gyre were in a weak mode during 19

the bentong raub suture zone abstract it is proposed that the bentong raub suture zone represents a segment of the main devonian to middle triassic palaeo tethys ocean and forms the boundary between the gondwana derived sibumasu and indochina terranes palaeo tethyan oceanic ribbon bedded cherts preserved in the suture zone range in age from middle devonian to middle permian and melange includes chert and limestone clasts that range in age from lower carboniferous to lower permian this indicates that the palaeo tethys opened in the devonian when indochina and other chinese blocks separated from gondwana and closed in the late triassic peninsular malaysia segment the suture zone is the result of northwards subduction of the palaeo tethys ocean beneath indochina in the late palaeozoic and the triassic collision of the sibumasu terrane with and the underthrusting of indochina tectonostratigraphic palaeobiogeographic and palaeomagnetic data indicate that the sibumasu terrane separated from gondwana in the late sakmarian and then drifted rapidly northwards during the permian triassic during the permian subduction phase the east malaya volcano plutonic arc with i type granitoids and intermediate to acidic volcanism was developed on the margin of indochina the main structural discontinuity in peninsular malaysia occurs between palaeozoic and triassic rocks and orogenic deformation appears to have been initiated in the upper permian to lower triassic when sibumasu began to collide with indochina during the early to middle triassic a type subduction and crustal thickening generated the main range syn to post orogenic granites which were emplaced in the late triassic early jurassic a foredeep basin developed on the depressed margin of sibumasu in front of the uplifted accretionary complex in which the semanggol formation rocks accumulated the suture zone is covered by a latest triassic jurassic and cretaceous mainly continental red bed overlap sequence

the igneous rocks of singapore new insights to palaeozoic and mesozoic assembly of the sukhothai arc abstract six plutons of granitic to gabbroic rocks have been recognised in the poorly exposed ground of north and east singapore using new data from borehole cores and field observations five of the plutons were emplaced sequentially during the period 285 230 ma and these have been grouped within a single parent unit bukit timah centre in a new lithodemic framework for singapore these plutons record the development of early permian to triassic arc related magmatism towards the southern end of the sukhothai arc system of thailand peninsular malaysia and indonesia compositional trends in the plutons record decreasing crustal contribution as the arc matured the volcanosedimentary succession underlying southwest singapore records contemporaneous deposition in the forearc basin and includes pyroclastic units of sufficient thickness and extent to be assigned member status in a new lithostratigraphical framework for singapore the largest pyroclastic unit which is 150 m thick developed as volcanic activity peaked at c 242 ma and is correlated with a large probably caldera forming eruption of one of the permo triassic plutons the composition typology and age of the bukit timah centre plutons confirm their affinity with eastern belt intrusions of the eastern province one of three granitoid provinces in southeast asia and support a widely accepted model that eastern province granitoids formed in an andean type setting as palaeo tethys crust descended beneath the indochina east malaya block widespread development of hydrothermal tuffisite in the permo triassic intrusions is correlated tentatively with rapid uplift following slab breakoff when arc activity ceased in the singapore region in the interval c 230 205 ma a sixth pluton much younger than and unrelated to the bukit timah centre was emplaced in northeast singapore in the upper cretaceous

seasonality in transition scale from balanced to unbalanced motions in the world ocean abstractthe transition scale lt from balanced geostrophic motions to unbalanced wave motions including near inertial flows internal tides and inertia gravity wave continuum is explored using the output from a global 1 48 horizontal resolution massachusetts institute of technology general circulation model mitgcm simulation defined as the wavelength with equal balanced and unbalanced motion kinetic energy ke spectral density lt is detected to be geographically highly inhomogeneous it falls below 40 km in the western boundary current and antarctic circumpolar current regions increases to 40 100 km in the interior subtropical and subpolar gyres and exceeds in general 200 km in the tropical oceans with the exception of the pacific and indian sectors of the southern ocean the seasonal ke fluctuations of the surface balanced and unbalanced motions are out of phase because of the occurrence of mixed layer instability in winter and trapping of unbalanced motion ke in shallow mixed layer in summe

anticyclonic eddy sheddings from kuroshio loop and the accompanying cyclonic eddy in the northeastern south china sea abstractsheddings of kuroshio loop current klc eddies in the northeastern south china sea scs are investigated using mooring arrays multiple satellite data and data assimilative hycom products based on altimeter sea surface heights between 1992 and 2014 a total of 19 prominent klc eddy shedding klces events were identified among which four events were confirmed by the concurrent moored and satellite observations compared to the leaping behavior of kuroshio klces is a relatively short duration phenomenon that primarily occurs in boreal autumn and winter the klc and its shedding anticyclonic eddy ae trap a large amount of pacific water with high temperature salinity and low chlorophyll concentration in the upper layer the corresponding annual mean transport caused by klces reaches 0 24 0 38 sv 1 sv 106 m3 s 1 accounting for 6 8 10 8 of the upper layer luzon strait transport altimeter based statistics show that among 90 of the historical klces events a cyclonic eddy ce is immedi

three dimensional reconstruction of oceanic mesoscale currents from surface information the ability to reconstruct the three dimensional 3d dynamics of the ocean by an effective version of surface quasi geostrophy esqg is examined using the fact that surface density plays an analogous role as interior potential vorticity pv the esqg method consists in inverting the qg pv generated by sea surface density only we also make the extra assumption that sea surface temperature sst anomalies fully represent surface density anomalies this approach requires a single snapshot of sst and the setup of two parameters the mean brunt vaisala frequency and a parameter that determines the energy level at the ocean surface the validity of this approach is tested using an ocean general circulation model simulation representing the north atlantic in winter it is shown that the method is quite successful in reconstructing the velocity field at the ocean surface for mesoscales between 30 and 300 km the esqg framework can also be applied to reconstruct subsurface fields using surface information results show that the reconstruction of velocities and vorticity from surface fields is reasonably good for the upper 500 m and that the success of the method mainly depends on the quality of the sst as a proxy of the density anomaly at the base of the mixed layer this situation happens after a mixed layer deepening period therefore the ideal situation for the application of this method would be after strong wind events

reconstructing the ocean s interior from surface data a new method is proposed for extrapolating subsurface velocity and density fields from sea surface density and sea surface height ssh in this the surface density is linked to the subsurface fields via the surface quasigeostrophic sqg formalism as proposed in several recent papers the subsurface field is augmented by the addition of the barotropic and first baroclinic modes whose amplitudes are determined by matching to the sea surface height pressure after subtracting the sqg contribution an additional constraint is that the bottom pressure anomaly vanishes the method is tested for three regions in the north atlantic using data from a high resolution numericalsimulation the decomposition yields strikinglyrealistic subsurfacefields it is particularly successful in energetic regions like the gulf stream extension and at high latitudes where the mixed layer is deep but it also works in less energetic eastern subtropics the demonstration highlights the possibility of reconstructing three dimensional oceanic flows using a combination of satellite fields for example seasurfacetemperature sst andssh andsparse orclimatological estimatesoftheregionaldepthresolveddensity themethodcouldbefurtherelaboratedtointegrateadditionalsubsurfaceinformation such as mooring measurements

simulations of temperature and turbulence structure of the oceanic boundary layer with the improved near surface process an improved model for the oceanic boundary layer is presented in view of the recent observation of the microstructure of the upper ocean including the high dissipation rate near the sea surface in the new model the surface boundary conditions for both the turbulent kinetic energy flux and the roughness length scale are modified the parameterization of stratification effects on turbulence is improved and the convective process is reformulated on the basis of the observation of uniform temperature and velocity profiles within the convective mixed layer evolutions of the profiles of both the dissipation rate and temperature of the observation data patches experiment as well as the time series of the sea surface temperature over the observation days are successfully simulated during a diurnal cycle for the first time it is also shown that the model reproduces various important features of the oceanic boundary layer for example the formation of a diurnal thermocline the profiles of buoyancy flux and the magnitudes of the buoyancy gradients both within the mixed layer and at the diurnal thermocline performance of the model is compared with that of the widely used mellor yamada model

petrogenesis of malaysian granitoids in the southeast asian tin belt part 2 u pb zircon geochronology and tectonic model in our complementary geochemical study part 1 the malaysian granitoids of the southeast asian tin belt were divided into a middle permian to late triassic i type dominated eastern province indochina terrane and a triassic to early jurassic transitional i s type main range province sibumasu terrane separated by the bentong raub suture zone which closed in the late triassic previous geochronology has relied on only a few u pb zircon ages together with k ar and whole rock rb sr ages that may not accurately record true magmatic ages we pre sent 39 new high precision u pb zircon ion microprobe ages from granitoids and vol canics across the malay peninsula our results show that ages from the eastern province granitoids span 289 220 ma with those from the main range province granitoids being entirely late triassic spanning 227 201 ma a general westerly younging magmatic trend across the malay peninsula is considered to refl ect steepening and roll back of the bentong raub subduction zone during progressive closure of paleo tethys the youngest ages of subduction related granites in the eastern province roughly coincide with the youngest ages of marine sedimentary rocks along the paleo tethyan suture zone our petrogenetic and u pb zircon age data support models that relate the eastern province granites to pre collisional andean type magmatism and the western main range province granites to syn and post collisional crustal melting of sibumasu crust during the late triassic tin mineralization was mainly associated with the latter phase of magmatism two alternative tectonic models are discussed to explain the triassic evolution of the malay peninsula the fi rst involves a second late triassic to jurassic or early cretaceous east dipping subduction zone west of sibumasu where subduction related hornblende and biotite bearing granites along sibumasu are paired with main range crustal melt tinbearing granites analogous to the bolivia cordilleran tin bearing granite belt the second model involves westward underthrusting of indochina beneath the west malaya main range province resulting in crustal thickening and formation of tin bearing granites of the main ranges cretaceous granitoids are also present locally in singapore ubin diorite on tioman island in the noring pluton of the stong complex eastern province and along the sibumasu terrane in southwest thailand and burma myanmar refl ecting localized crustal melting

beyond goce for the ocean circulation estimate synergetic use of altimetry gravimetry and in situ data provides new insight into geostrophic and ekman currents accurate estimate of ocean surface currents is both a challenging issue and a growing end users requirement in this paper ocean currents are calculated at two levels surface and 15 m depth as the sum of the geostrophic and ekman components first a new global 14 mean dynamic topography called the cnes cls13 mdt has been calculated and is now available for use by the oceanographic community by exploiting information from surface drifters and argo floats the new mdt resolves spatial scales beyond the resolution permitted by the recent gravity and ocean circulation experiment goce geoid models 125 km associated mean geostrophic speeds in strong currents are increased by 200 on average compared to goce based mean currents in addition for the first time a two level monthly empirical ekman model that samples a spiral like behavior is estimated we show that combining both pieces of information leads to improved ocean currents compared to other existing observed products

mesoscale to submesoscale transition in the california current system part i flow structure eddy flux and observational tests in computational simulations of an idealized subtropical eastern boundary upwelling current system similar to the california current a submesoscale transition occurs in the eddy variability as the horizontal grid scale is reduced to o 1 km this first paper in a series of three describes the transition in terms of the emergent flow structure and the associated time averaged eddy fluxes in addition to the mesoscale eddies that arise from a primary instability of the alongshore wind driven currents significant energy is transferred into submesoscale fronts and vortices in the upper ocean the submesoscale arises through surface frontogenesis growing off upwelled cold filaments that are pulled offshore and strained in between the mesoscale eddy centers in turn some submesoscale fronts become unstable and develop submesoscale meanders and fragment into roll up vortices associated with this phenomenon are a large vertical vorticity and rossby number a large vertical velocity relatively flat horizontal spectra contrary to the prevailing view of mesoscale dynamics a large vertical buoyancy flux acting to restratify the upper ocean a submesoscale energy conversion from potential to kinetic a significant spatial and temporal intermittency in the upper ocean and material exchanges between the surface boundary layer and pycnocline comparison with available observations indicates that submesoscale fronts and instabilities occur widely in the upper ocean with characteristics similar to the simulations

variability of internal tides and near inertial waves on the continental slope of the northwestern south china sea structure and variability of internal tides it and near inertial waves niw on the continental slope of the northwestern south china sea were investigated based on 9 month moored current observations from autumn to early summer in 2008 and 2009 the diurnal it kinetic energy dominant over that of semidiurnal tides is found to exhibit apparent seasonal variability strongest in summer and weakest in winter whereas the semidiurnal variance remained nearly uniform throughout the observation period moreover the diurnal it were more coherent i e phase locked to the astronomical forcing than the semidiurnal constituents coherent diurnal variance accounts for about 40 of diurnal motions but semidiurnal tides contain a much smaller fraction 10 of coherent motions further analysis demonstrates that the diurnal it are dominated by the first mode whereas the semidiurnal tides show a variable multimodal structure the second mode is dominant in summer and comparable to the first mode in spring and autumn but the first mode predominates in winter multimodal semidiurnal it are more influenced by varying stratification structures and background currents and thus exhibit highly incoherent and intermittent behavior which may wash out seasonal variability during their long propagation from the generation source the observed niw are seasonally independent and comparable to the semidiurnal motions during the passage of typhoon hagupit however the niw became the most energetic component of the inertia gravity waveband motions niw energy and shear were significantly enhanced and exceeded tidal counterparts by a factor of 2 to 3 in the upper layer

a new estimate of the global 3d geostrophic ocean circulation based on satellite data and in situ measurements abstract a new estimate of the global ocean 3d geostrophic circulation from the surface down to 1500 m depth surcouf3d has been computed for the 1993 2008 period using an observation based approach that combines altimetry with temperature and salinity through the thermal wind equation the validity of this simple approach was tested using a consistent dataset from a model reanalysis away from the boundary layers errors are less than 10 in most places which indicate that the thermal wind equation is a robust approximation to reconstruct the 3d oceanic circulation in the ocean interior the surcouf3d current field was validated in the atlantic ocean against in situ observations we considered the andro current velocities deduced at 1000 m depth from argo float displacements as well as velocity measurements at 26 5 n from the rapid mocha current meter array the surcouf3d currents show similar skill to the 3d velocities from the glorys mercator ocean reanalysis in reproducing the amplitude and variability of the andro currents in the upper 1000 m high correlations are also found with in situ velocities measured by the rapid mocha current meters the surcouf3d current field was then used to compute estimates of the atlantic meridional overturning circulation amoc through the 25 n section showing good comparisons with hydrographic sections from 1998 and 2004 monthly averaged amoc time series are also consistent with the rapid mocha array and with the glorys mercator ocean reanalysis over the april 2004 september 2007 period finally a 15 years long time series of monthly estimates of the amoc was computed the amoc strength has a mean value of 16 sv with an annual resp monthly standard deviation of 2 4 sv resp 7 1 sv over the 1993 2008 period the time series characterized by a strong variability shows no significant trend

palaeogeography of late triassic red beds in singapore and the indosinian orogeny abstract a red bed facies of the upper triassic jurong formation has been logged on sentosa island singapore an overall coarsening and thickening upward pattern is well developed the lower part of the section is dominated by purple red massive to finely laminated illite smectite kaolin rich mudstones containing thin discontinuous lenses of fine sandstone marked by low angle lamination and small ripples one dinosaur like foot print has been discovered in a loose block of red mudstone it is concluded that this is a lacustrine sequence and it is proposed to name the lake lake sentosa the upper part of the sequence consists of flat laminated to trough cross bedded medium grained sandstone and granule to cobble conglomerates alternating with purple red mudstone the mudstone sandstone packages are arranged in decametre scale coarsening upward cycles the channelling and decimetre scale cross bedding characterising the sandstone and conglomeratic beds is evidence for deposition by flashy fluvial flood processes possibly feeding into the lake as a fresh water delta one possible dinosaur trackway in granule size conglomerate has been located detrital zircon u pb ages vary from 2 7 ba to 209 ma with significant populations at 245 ma and 220 ma these ages throw light on the timing of the indosinian orogeny the molasse red beds of the jurong formation were deposited in a half graben formed in the hangingwall of the bukit timah fault when central peninsular malaysia went into extension following the climax of the indosinian orogeny in the late triassic

oceanic restratification forced by surface frontogenesis potential vorticity pv conservation implies a strong constraint on the time evolution of the mean density at a given depth the authors show that on an f plane and in the absence of sources and sinks of pv it only depends on two terms namely the time evolution of the product between density anomaly and relative vorticity and the vertical pv flux this primitive equation result which applies at any depth suggests that the ageostrophic dynamics induced by baroclinic eddies strongly affect the mean oceanic stratification profile this result is illustrated for two simple initial value simulations of a baroclinic balanced jet for initial situations propitious to surface frontogenesis the simulations show a restratification over the whole water column characterized by the amplification in time of the brunt vaisala frequency in the upper oceanic layers in the absence of surface frontogenesis such as when the jet is initialized at the middepth of the water column the restratification is much weaker and slower because both simulations have similar kinetic energy and growth rate of baroclinic instability the results clearly reveal that the restratification is driven by surface frontogenesis in the first case and by vertical pv flux in the interior in the second case the authors also point out that the dynamics of the interior pv is tightly related to the surface dynamics because of total mass conservation

reconstruction of ocean s interior from observed sea surface information observational surface data are used to reconstruct the ocean s interior through the interior surface quasigeostrophic isqg method the input data include the satellite derived sea surface height satellite derived sea surface temperature satellite derived or argo based sea surface salinity and an estimated stratification of the region the results show that the isqg retrieval of subsurface density anomalies is quite promising compared to argo profile data at 1000 m depth the directions of retrieved velocity anomalies are comparable to those derived from argo float trajectories the reconstruction using surface density input field approximated only by sst with constant sss performs less satisfactorily than that taking into account the contribution of sss perturbations suggesting that the observed sss information is important for the application of the isqg method better reconstruction is obtained in the warm season than in the cold season which is probably due to the stronger stratification in the warm season that confines the influence of the biases in the surface input data especially sss in a shallow layer the comparison between the performance of isqg with argo based sss input and that with satellite derived sss input suggests that the biases in the sss products could be a major factor that influences the isqg performance with reduced biases in satellite derived sss in the future the measurement based isqg method is expected to achieve better reconstruction of ocean interior and thus is promising in practical application

inferring dynamics from the wavenumber spectra of an eddying global ocean model with embedded tides 1 the slopes of the wavenumber spectra of sea surface height ssh and kinetic energy ke have been used to infer interior or surface quasi geostrophic qg or sqg dynamics of the ocean however inspection of spectral slopes for altimeter ssh in the mesoscale band of 70 to 250 km shows much flatter slopes than the qg or sqg predictions over most of the ocean comparison of altimeter wavenumber spectra with spectra from an eddy resolving global ocean circulation model the hybrid coordinate ocean model hycom at 1 12 5 equatorial resolution which has embedded tides suggests that the flatter slopes of the altimeter ssh may arise from three possible sources 1 presence of strong internal tides 2 shift of the inertial sub range to smaller scales and 3 altimeter noise artificially adding noise to the model tends to flatten the spectra for low ke regions near internal tide generating regions spectral slopes in the presence of internal waves are much flatter than qg or sqg predictions separating the variability into high and low frequency around periods of 2 days then a different pattern emerges with a flat high frequency wavenumber spectrum and a steeper low frequency wavenumber spectrum for low mesoscale ke the inertial sub range defined by the nearly flat enstrophy band moves to smaller scales and the mesoscale band of 70 to 250 km no longer represents the inertial sub range the model wavenumber spectra are consistent with qg and sqg theory when internal waves and inertial sub range shifts are taken into consideration

tectonic framework and phanerozoic evolution of sundaland abstract sundaland comprises a heterogeneous collage of continental blocks derived from the india australian margin of eastern gondwana and assembled by the closure of multiple tethyan and back arc ocean basins now represented by suture zones the continental core of sundaland comprises a western sibumasu block and an eastern indochina east malaya block with an island arc terrane the sukhothai island arc system comprising the linchang sukhothai and chanthaburi blocks sandwiched between this island arc formed on the margin of indochina east malaya and then separated by back arc spreading in the permian the jinghong nan uttaradit and sra kaeo sutures represent this closed back arc basin the palaeo tethys is represented to the west by the changning menglian chiang mai inthanon and bentong raub suture zones the west sumatra block and possibly the west burma block rifted and separated from gondwana along with indochina and east malaya in the devonian and were accreted to the sundaland core in the triassic west burma is now considered to be probably cathaysian in nature and similar to west sumatra from which it was separated by opening of the andaman sea basin south west borneo and or east java west sulawesi are now tentatively identified as the missing argoland which must have separated from nw australia in the jurassic and these were accreted to se sundaland in the cretaceous revised palaeogeographic reconstructions illustrating the tectonic and palaeogeographic evolution of sundaland and adjacent regions are presented

effect of mesoscale eddies on subtropical mode water variability from the kuroshio extension system study kess abstract forty eight profiling floats have been deployed in the kuroshio extension ke region since may 2004 as part of the kuroshio extension system study kess project by combining the float temperature salinity measurements with satellite altimetry data this study investigates the role played by mesoscale eddies in controlling the property changes in north pacific subtropical mode water stmw following a 3 yr period of low eddy activity in 2002 04 the ke showed a transition to a high eddy kinetic energy state in 2005 this transition is the result of delayed oceanic response to the 2002 shift in the basin scale surface wind forcing in connection with the pacific decadal oscillation the high eddy kinetic energy state of the ke is characterized by successive shedding of strong cold core rings into the recirculation gyre resulting from the interaction of the ke jet with the shatsky rise or the preexisting cutoff rings by transporting northern origin high potential vorticity pv ke water into t

dynamics of the upper oceanic layers in terms of surface quasigeostrophy theory in this study the relation between the interior and the surface dynamics for nonlinear baroclinically unstable flows is examined using the concepts of potential vorticity first it is demonstrated that baroclinic unstable flows present the property that the potential vorticity mesoscale and submesoscale anomalies in the ocean interior are strongly correlated to the surface density anomalies then using the invertibility of potential vorticity the dynamics are decomposed in terms of a solution forced by the three dimensional 3d potential vorticity and a solution forced by the surface boundary condition in density it is found that in the upper oceanic layers the balanced flow induced only by potential vorticity is strongly anticorrelated with that induced only by the surface density with a dominance of the latter the major consequence is that the 3d balanced motions can be determined from only the surface density and the characteristics of the basin scale stratification by solving an elliptic equation these properties allow for the possibility to reconstruct the 3d balanced velocity field of the upper layers from just the knowledge of the surface density by using a simpler model that is an effective surface quasigeostrophic model all these results are validated through the examination of a primitive equation simulation reproducing the dynamics of the antarctic circumpolar current

granitic magmatism basement ages and provenance indicators in the malay peninsula insights from detrital zircon u pb and hf isotope data abstract the malay peninsula lies on two continental blocks sibumasu and east malaya which are intruded by granitoids in two provinces the main range and eastern previous models propose that permian triassic granitoids are subduction related and syn to post collisional we present 752 u pb analyses that were carried out on zircons from river sands in the malay peninsula of these 243 grains were selected for hf isotope analyses our data suggest a more complex sibumasu east malaya collision history 176hf 177hfi ratios reveal that permian triassic zircons were sourced from three magmatic suites a permian crustally derived granitoids b early middle triassic granitoids with mixed mantle crust sources and c late triassic crustally derived granitoids this suggests three permian triassic episodes of magmatism in the malay peninsula two of which occurred in the eastern province although the exact timing of the sibumasu east malaya collision remains unresolved current data suggest that it occurred before the late triassic probably in late permian early triassic our data also indicate that sibumasu and east malaya basements are chronologically heterogeneous but predominantly of proterozoic age some basement may be neoarchaean but there is no evidence for basement older than 2 8 ga finally we show that hf isotope signatures of triassic zircons can be used as provenance indicators

u pb zircon geochronology of early permian to late triassic rocks from singapore and johor a plate tectonic reinterpretation article i nfo the results of u pb zircon geochronology of permian to middle triassic granitoids from singapore and neighbouring johor are presented rhyolite from pulau sibu is 276 5 ma gabbros from singapore give ages of 260 2 to 249 2 ma granites from singapore give ages from 249 2 to 230 6 ma and rhyolite from telkuma gives an age of 238 2 ma u pb detrital zircon age spectra from a late triassic conglomerate from singapore show carboniferous mid dle triassic and late triassic spikes at 350 245 and 217 ma respectively these new data when combined with published u pb zircon ages allow a revision of the plate tectonic evolution of the malaysian peninsula region a tin bearing magmatic arc evolved in the eastern malaysian peninsula part of indochina from the early permian to the middle triassic when the palaeo tethys ocean was subducted and sibumasu continental lithosphere was rifted from pangea this opened up the neo tethys ocean that the granitoid ages show a progressive decrease in age from pulau sibu 276 5 ma to singapore 230 6 ma suggests that during this andean type orogenic phase the subduction zone rolled back and steepened causing the locus of mainly i type magmatism to migrate from east to west in present day coordinates across the eastern and central belts and stretch the lithosphere as it did so in the late triassic sibumasu collided with indochina causing the western belt sibumasu to over thrust the central belt indochina along the bentong raub suture the lower half of the thickened crust formally the tin bearing indochina plate was partially melted and pre dominantly s type tin bearing granites were intruded into the upper crust formally sibumasu this late triassic collisional phase is the indosinian orogeny in peninsular malaysia

tectonic evolution of the sibumasu indochina terrane collision zone in thailand and malaysia constraints from new u pb zircon chronology of se asian tin granitoids three principal granite provinces are defined across se asia as follows 1 the western thailand myanmar burma province consists of hornblende biotite i type granodiorite granites and felsic biotite k feldspar garnet tourmaline granites associated with abundant tin mineralization in greisen type veins new ion microprobe u pb dating results from phuket island show zircon core ages of 212 2 and 214 2 ma and a thermal overprint with rims of 81 2 1 2 and 85 75 ma 2 the north thailand west malaya main range province has mainly s type biotite granites and abundant tin mineralization resulting from crustal thickening following collision of the sibumasu plate with indochina during the mid triassic biotite granites around kuala lumpur contain extremely u rich zircons up to 38000 ppm that yield ages of 215 7 and 210 7 ma 3 the east malaya province consists of dominantly permian triassic i type hornblende biotite granites but with subordinate s type plutons and a type syenite gabbros biotite k feldspar granites from tioman island off the east coast of malaysia also yield a zircon age of 80 1 ma showing cretaceous magmatism in common with province 1 geological and u pb geochronological data suggest that two east dipping in present day coordinates subduction zones are required during the triassic one along the bentong raub palaeo tethyan suture and the other west of the phuket burma province 1 belt supplementary material a full description of u pb analytical methods used and data tables are available at www geolsoc org uk sup18523

diagnosing surface mixed layer dynamics from high resolution satellite observations numerical insights high resolution numerical experiments of ocean mesoscale eddy turbulence show that the wind driven mixed layer ml dynamics affects mesoscale motions in the surface layers at scales lower than o 60 km at these scales surface horizontal currents are still coherent to but weaker than those derived from sea surface height using geostrophy vertical motions on the other hand are stronger than those diagnosed using the adiabatic quasigeotrophic qg framework an analytical model based on a scaling analysis and on simple dynamical arguments provides a physical understanding and leads to a parameterization of these features in terms of vertical mixing these results are valid when the wind driven velocity scale is much smaller than that associated with eddies and the ekman number related to the ratio between the ekman and ml depth is not small this suggests that in these specific situations three dimensional ml motions including the vertical velocity can be diagnosed from high resolution satellite observations combined with a climatological knowledge of ml conditions and interior stratification