chemical geodynamics in the back arc region of japan based on the trace element and srnd isotopic compositions 143nd144nd 87sr86sr trace and major element results are reported for cenozoic alkaline basalts and associated tholeiitic basalts from southwestern japan and some from korea and china most of the samples plot within the mantle array with nd values ranging from 5 0 to 3 2 and 87sr86sr ratios ranging from 0 7037 to 0 7057 the isotopic variations observed along traverse sections of alkaline basalts from the trench to the continental sides of southwestern japan do not suggest a direct relationship between the subduction of the philippine sea and pacific plates and the generation of alkaline basalt magmas however in southwestern japan the alkaline basalts do show evidence of a subducted component and are more enriched in the mobile incompatible elements such as rb ba and k relative to chinese and korean basalts negative correlations between nd and sm nd and between nd and la th as well as a positive correlation between 87sr86sr and la th are recognized in some of the basalts these relationships indicate at least two component magma mixing between 1 magma resulting from a small melting from a depleted mantle and 2 magma resulting from a relatively large amount of melting of an enriched mantle source it is suggested that the cenozoic alkaline basalts from southwestern japan korea and china are product of interaction between a morb type mantle and a deep mantle plume if the mantle plume has ascended from the upper mantle lower mantle or core mantle boundary the subducted pacific and philippine sea plates could not have extended to southwestern japan had they done so they would have arrested before they reached the melting zone the ascent of the plumes that produced the alkaline volcanism in southwestern japan

internal tide scattering at seamounts ridges and islands 1 the scattering of mode 1 internal tides from idealized gaussian topography in a nonrotating ocean with constant and realistic stratifications is examined with a primitive equation numerical model incident mode 1 energy fluxes of 20 and 2000 w m 1 are used to examine the linear regime and a more realistic situation simulations using two dimensional or infinite ridges compare well with ray tracing methods and illustrate how the size and shape of the topography influence wave scattering the height affects energy transmission and reflection while the slope and width determine the conversion of low mode internal tides into beams or higher modes three dimensional topographic scattering is considered for seamounts finite width ridges and islands scattering from finite ridges focuses wave energy directly downstream while scattering from seamounts produces azimuthal energy dispersion scattering to higher wave modes occurs in the lee of near critical and supercritical seamounts and ridges nonlinear interactions transfer energy into the mode 1 m4 internal tide the mellor yamada level 2 5 submodel parameterizes turbulent mixing for the near critical and supercritical ridges with realistic stratification elevated mixing is found over the leading edge of the topography and along a tidal beam up to the first surface bounce a transition from a beam structure near the topography to a low mode structure farther away occurs due to an increased contribution from the mode 1 internal tide as it refracts around the topography and not due to turbulent dissipation internal tide scattering at topography leads to a loss of energy to mixing and to a redistribution of energy flux in space frequency and mode number

nd and sr isotopic variations in acidic rocks from japan significance of upper mantle heterogeneity initial nd and sr isotopic ratios have been measured for cretaceous acidic and related intermediate rocks 24 volcanic and two plutonic rocks from the inner zone of southwest japan izswj to investigate the genesis of acidic magmas the initial nd and sr isotopic ratios for these rocks show three interesting features 1 end values for acidic rocks 2 to 9 are negatively correlated with esr values 10 to 90 together with those for intermediate rocks end 3 to 8 esr 0 to 65 2 the end values for silica rich rocks 60 sio2 correlate with the longitude of the sample locality decreasing from west to east in a stepwise fashion four areas characterized by uniform end values are discriminated 3 low silica rocks 60 sio2 in a certain area have distinctly different end values from those of the high silica rocks in the same area

simulating bank erosion over an extended natural sinuous river reach using a universal slope stability algorithm coupled with a morphodynamic model meandering river channels are often associated with cohesive banks yet only a few river modelling packages include geotechnical and plant effects existing packages are solely compatible with single threaded channels require a specific mesh structure derive lateral migration rates from hydraulic properties determine stability based on friction angle rely on nonphysical assumptions to describe cutoffs or exclude floodplain processes and vegetation in this paper we evaluate the accuracy of a new geotechnical module that was developed and coupled with telemac mascaret to address these limitations innovatively the newly developed module relies on a fully configurable universal genetic algorithm with tournament selection that permits it 1 to assess geotechnical stability along potentially unstable slope profiles intersecting liquid solid boundaries and 2 to predict the shape and extent of slump blocks while considering mechanical plant effects bank hydrology and the hydrostatic pressure caused by flow the profiles of unstable banks are altered while ensuring mass conservation importantly the new stability module is independent of mesh structure and can operate efficiently along multithreaded channels cutoffs and islands data collected along a 1 5 km long reach of the semialluvial medway creek canada over a period of 3 5 years are used to evaluate the capacity of the coupled model to accurately predict bank retreat in meandering river channels and to evaluate the extent to which the new model can be applied to a natural river reach located in a complex environment our results indicate that key geotechnical parameters can indeed be adjusted to fit observations even with a minimal calibration effort and that the model correctly identifies the location of the most severely eroded bank regions the combined use of genetic and spatial analysis algorithms in particular for the evaluation of geotechnical stability independently of the hydrodynamic mesh permits the consideration of biophysical conditions for an extended river reach with complex bank geometries with only a minor increase in run time further improvements with respect to plant representation could assist scientists in better understanding channel floodplain interactions and in evaluating channel designs in river management projects

on sampling the ocean using underwater gliders surface to 1000 m and back took 5 6 h and covered 5 3 km resulting in a horizontal speed of 0 26 m s 1 seasoar undulated between the surface and 400 m completing a cycle in 11 min while covering 2 6 km for a speed of 3 9 m s 1 adjacent profiles of temperature and salinity are compared between the two platforms to prove that each is accurate spray and seasoar data are compared through sections isopycnal spatial series and wave number spectra the relative slowness of the glider results in the projection of high frequency oceanic variability such as internal waves onto spatial structure the projection is caused by doppler smearing because of finite speed and aliasing due to discrete sampling the projected variability is apparent in properties measured on depth surfaces or in isopycnal depth no projected variability is seen in observations of properties on constant density surfaces because internal waves are intrinsically filtered wave number spectra suggest that projected variability affects properties at constant depth at wavelengths shorter than 30 km these results imply that isobaric quantities like geostrophic shear are valid at wavelengths longer than 30 km while isopycnal quantities like spice may be analyzed for scales as small as a glider measures

internal tidal energy fluxes in the south china sea from density and velocity measurements by gliders 1 internal tidal energy fluxes were obtained from june 2011 to august 2011 using underwater gliders in the south china sea spray gliders profiled every 2 h to 500 m which is deep enough given the shallow thermocline to compute mode 1 fluxes from vertical mode fits to tidal displacements and currents westward mode 1 diurnal and semidiurnal fluxes exceeded 40 and 30 kw m 1 to our knowledge these flux observations are the first from both velocity and density measurements by gliders fluxes compare well with a mooring near a generation site in southern luzon strait and a regional model furthermore the zonal depth structure of the internal tide is obtained by binning measurements which cover four spring neap cycles and over 100 km along 20 39 n westward phase propagation is found for currents and displacements while roughly constant phase is found along beams both these features of the phase suggest a narrow banded internal tide semidiurnal energy density is largest along a raypath which coincides with generation sites on both the eastern and western ridges in luzon strait diurnal energy density is surface intensified consistent with relatively shallower diurnal raypaths emanating from the eastern ridge

geochemistry of quaternary basaltic lavas in the norikura area central japan influence of the subcontinental upper mantle on the trace elements and sr isotope compositions abstract the trend of across arc major and trace element compositions and 87sr 86sr ratios for quaternary lavas from the western part of central japan are different from those from ne japan basalts from the norikura area located at the backarc side of the western part of central japan are characterized by lower k zr and higher 87sr 86sr 0 705 0 706 than those of the backarc side of ne japan beneath the norikura area the pacific plate is subducting at the depth where dehydration of phlogopite in the down dragged peridotite occurs through dehydration fluid is added to the mantle wedge which consists of a n morb like source triggering partial melting and producing uprising mantle diapirs these diapirs have high k zr and low 87sr 86sr as indicated by basalts in the backarc side of ne japan subcontinental mantle materials which have low lil hfs and high 87sr 86sr exist in the uppermost portions of the mantle wedge beneath the norikura area and interact geochemically with the uprising diapirs the geochemical characteristics of the norikura area may be attributed to the involvement of the subcontinental upper mantle

a simulation model of morphological vegetation and sediment changes in ephemeral streams a model to simulate channel changes in ephemeral river channels and to test the effects of hydrological changes due to climate change and sol or land use change was developed under the auspices of the eu funded medalus programme mediterranean desertification and land use the model changism channel change gis simulation model is designed to simulate the effect of channel flow events and of climate conditions on morphology sediment and vegetation through sequences of events and conditions over periods of up to several decades the modelling is based on cellular automata but with calculations for water and sediment continuity process rules have both deterministic and stochastic elements an important feature of the model is that it incorporates feedback elements between each event the main aim of the model is to indicate the likely outcomes of events and combinations of conditions it is linked to gis for both input and output the modelling is based on a channel reach and state is input as gis layers of morphology dem sediment and vegetation cover and state other initial conditions of soil moisture groundwater level and overall gradient are input parameters for processes are read from tables and can be easily changed for successive runs of the model the bases for decisions on process specifications are discussed in this paper initial tests of the operation and sensitivity of the model were made on idealized reaches the model was then tested using data from monitored sites in se spain simulations using clearwater flow worked well but initial simulations using events with sediment loads showed some tendency for excess deposition further tests and modifications are taking place overall the model is one of the most sophisticated that simulates the interaction of flows with sediment and vegetation and the outcomes in terms of erosion deposition morphology sediment cover vegetation cover and plant survival over periods of up to 30 years for the scale of a channel reach copyright 2005 john wiley sons ltd

poleward flows in the southern california current system glider observations and numerical simulation 1 three years of continuous spray glider observations in the southern california current system ccs are combined with a numerical simulation to describe the mean and variability of poleward flows in the southern ccs gliders provide upper ocean observations with good across shore and temporal resolution along two across shore survey lines while the numerical simulation provides a dynamically consistent estimate of the ocean state persistent poleward flows are observed in three areas within 100 km of the coast at point conception within the southern california bight scb and offshore of the scb and the santa rosa ridge srr poleward transport by the flows within the scb and offshore of the srr exceeds the poleward transport off point conception suggesting that the poleward flows are not continuous over the 225 km between observation lines the numerical simulation shows offshore transport between the survey lines that is consistent with some of the poleward flow turning offshore before reaching point conception the poleward current offshore of the srr is unique in that it is strongest at depths greater than 350 m and it is observed to migrate westward away from the coast this westward propagation is tied to westward propagating density anomalies originating in the scb during the spring summer upwelling season when wind stress curl is most strongly positive the across shore wave number frequency and phase speed of the westward propagation and the lack of across shore transport of salinity along isopycnals are consistent with first mode baroclinic rossby dynamics

surface manifestation of internal tides in the deep ocean observations from altimetry and island gauges the sea surface height signatures of internal tides in the deep ocean amounting to a few centimeters or less are studied using two complementary measurement types satellite altimetry and island tide gauges altimetry can detect internal tides that maintain coherence with the astronomical forcing island gauges can monitor temporal variability which in some circumstances is due to internal tides varying in response to changes in the oceanic medium this latter mechanism is at work at hilo and other stations on the northern coasts of the hawaiian islands by detecting spatially coherent low frequency internal tide modulations the tide gauges along with inverted echo sounders at sea suggest that the mean internal tide is also spatially coherent satellite altimetry confirms this at hawaii and in many other places topex poseidon altimetry detects mean surface waves spatially coherent and propagating great distances 1000 km before decaying below background noise when temporal variability is small the altimetry plus information on ocean density sets useful constraints on energy fluxes into internal tides at the hawaiian ridge 15 gw of tidal power is being converted from barotropic to first mode baroclinic motion examples elsewhere warn that a simplistic interpretation of the altimetry without regard to variability noise or in situ information may be highly misleading with such uncertainties extension of the hawaiian results into a usefully realistic estimate of the global internal tide energy balance appears premature at this time

a landslide dam breach induced debris flow a case study on downstream hazard areas delineation a catastrophic landslide dam breach induced debris flow initiated in da cu keng stream ruifang town when typhoon xangsane hit taiwan on november 1 2000 different available methodologies were used to model the natural dam breach induced debris flow and using field topography the hazard zones affected by debris mixtures were delineated the numerical finite element or finite difference method is time consuming for the simulation of debris flow inundation areas and hence a rules based gis geographic information system analysis is proposed in this study the model emphasizes the downstream inundated fan shaped areas covered by debris mixtures through the overflow point topography and gradient are assumed to dominate the debris masses deposition mechanism in the gis analysis the approach considers the parameters effects such as the runout distance the debris masses magnitude and the inundated areas the results of this study reveal that the gis process using the rule based approach speeds up the processing of delineating the hazard zones and assessment which can be applied to early warning and preliminary inundation hazardous mapping

propagation of internal tides generated near luzon strait observations from autonomous gliders 1 the vertical isopycnal displacements associated with internal waves generated by the barotropic tidal currents in the vicinity of luzon strait are estimated using measurements collected by autonomous underwater gliders nearly 23 000 profiles from seagliders and spray gliders collected during 29 different missions since 2007 are used to estimate the amplitude and phase of the linear semidiurnal and diurnal internal waves in this energetic region particularly in the previously poorly sampled area near the eastern ridge and on the pacific side of luzon strait the mean and variability of the internal wave field in the upper 1000 m of the water column are described the phase progression of internal waves as they propagate away from their generation sites is captured directly the glider based observations are used to map the mode 1 semidiurnal and diurnal internal wave fields providing the baroclinic energy flux over a roughly 600 km 800 km region based strictly on in situ observations

trapped diurnal internal tides propagating semidiurnal internal tides and mixing estimates in the california current system from sustained glider observations 2006 2012 abstract from 2006 2012 along 3 repeated cross shore transects california cooperative oceanic fisheries investigations lines 66 7 80 and 90 in the california current system 33 609 shear and 39 737 strain profiles from 66 glider missions are used to estimate mixing via finescale parameterizations from a dataset containing over 52 000 profiles elevated diffusivity estimates and energetic diurnal d1 and semidiurnal d2 internal tides are found a within 100 km of the coast on lines 66 7 and 80 and b over the santa rosa cortes ridge srcr in the southern california bight scb on line 90 while finding elevated mixing near topography and associated with internal tides is not novel the combination of resolution and extent in this ongoing data collection is unmatched in the coastal ocean to our knowledge both d1 and d2 internal tides are energy sources for mixing at these latitudes the d1 internal tide is subinertial on line 90 d1 and d2 tides are equally energetic over the srcr the main site of elevated mixing within the scb numerous sources of internal tides at the rough topography in the scb produce standing and or partially standing waves on lines 66 7 and 80 the dominant energy source below about 100 m for mixing is the d1 internal tide which has an energy density of the d2 internal tide on line 80 estimated diffusivity estimated dissipation and d1 energy density peak in summer the d1 energy density shows an increasing trend from 2006 to 2012 its amplitude and phase are mostly consistent with topographically trapped d1 internal tides traveling with the topography on their right the observed offshore decay of the diffusivity estimates is consistent with the exponential decay of a trapped wave with a mode 1 rossby radius of 20 30 km despite the variable mesoscale it is remarkable that coherent internal tidal phase is found

a preliminary investigation of the integration of modelled floodplain hydraulics with estimates of overbank floodplain sedimentation derived from pb 210 and cs 137 measurements this paper investigates the possibility of linking finite element modelled two dimensional hydraulics with floodplain sedimentation rates derived from radionuclide dating techniques the telemac 2d system is used to simulate the full dynamic velocity vector and water depth distributions for a 1 in 12 year flood event for the river culm devon these are compared to patterns of medium term 30 100 years sedimentation rates and a degree of correlation is found to exist this information is used to comment on the complexity of flow and sediment deposition interactions in floodplain environments and to provide a research design for the development of a more fully integrated floodplain morphodynamic model copyright 1999 john wiley sons ltd

relationships between mesoscale morphological units stream hydraulics and chinook salmon oncorhynchus tshawytscha spawning habitat on the lower yuba river california an expert based approach was used to identify 10 morphological unit types within a reach of the gravel bed regulated yuba river california that is heavily utilized by spawning chinook salmon oncorhynchus tshawytscha analysis of these units was carried out using two dimensional hydrodynamic modeling field based geomorphic assessment and detailed spawning surveying differently classified morphological units tended to exhibit discrete hydraulic signatures in most cases the froude number adequately differentiated morphological units but joint depth velocity distributions proved the most effective hydraulic classification approach spawning activity was statistically differentiated at the mesoscale of the morphological unit salmon preferred lateral bar riffle and riffle entrance units these units had moderately high velocity unit median 0 45 m s 1 and low depth unit median 0 6 m but each exhibited a unique joint depth velocity distribution a large proportion of redds 79 were associated with conditions of convective flow acceleration at riffle and riffle entrance locations in addition to reflecting microhabitat requirements of fish it was proposed that the hydraulic segregation of preferred from avoided or tolerated morphological units was linked to the mutual association of specific hydraulic conditions with suitable caliber sediment that promotes the provision and maintenance of spawning habitat

global patterns of low mode internal wave propagation part i energy and energy flux abstract extending an earlier attempt to understand long range propagation of the global internal wave field the energy e and horizontal energy flux f are computed for the two gravest baroclinic modes at 80 historical moorings around the globe with bandpass filtering the calculation is performed for the semidiurnal band emphasizing m2 internal tides generated by flow over sloping topography and for the near inertial band emphasizing wind generated waves near the coriolis frequency the time dependence of semidiurnal e and f is first examined at six locations north of the hawaiian ridge e and f typically rise and fall together and can vary by over an order of magnitude at each site this variability typically has a strong spring neap component in addition to longer time scales the observed spring tides at sites northwest of the hawaiian ridge are coherent with barotropic forcing at the ridge but lagged by times consistent with travel at the theoretical mode 1 group speed from the ridge phase c

engineered channel controls limiting spawning habitat rehabilitation success on regulated gravel bed rivers in efforts to rehabilitate regulated rivers for ecological benefits the flow regime has been one of the primary focal points of management strategies however channel engineering can impact channel geometry such that hydraulic and geomorphic responses to flow reregulation do not yield the sought for benefits to illustrate and assess the impacts of structural channel controls and flow reregulation on channel processes and fish habitat quality in multiple life stages a highly detailed digital elevation model was collected and analyzed for a river reach right below a dam using a suite of hydrologic hydraulic geomorphic and ecological methods results showed that despite flow reregulation to produce a scaled down natural hydrograph anthropogenic boundary controls have severely altered geomorphic processes associated with geomorphic self sustainability and instream habitat availability in the case study given the similarity of this stream to many others we concluded that the potential utility of natural flow regime reinstatement in regulated gravel bed rivers is conditional on concomitant channel rehabilitation

hot regions and the origin of marginal basins in the western pacific abstract volcanic provinces showing no genetic relationship to plate boundaries may be classified into two categories hot spots which are a few hundred kilometers across and may be nearly fixed in position with respect to deep mantle and hot regions which are a few thousand kilometers across and can migrate more freely the mantle upwellings which presumably give rise to them may originate at different depths by different causes it is observed that the marginal basins older than 15 ma of the western pacific become progressively younger northward with the exception of the south fiji basin this leads to the hypothesis that the spreading of marginal basins was caused by the mantle upwelling associated with a migrating hot region and that a hot region which started from the australia region in the late cretaceous migrated northward successively creating the tasman coral sea caroline south china parece vela shikoku and japan basins through paleocene eocene oligocene and early miocene time this hot region presently underlies northern china mongolia and adjacent areas another hot region is assumed to have caused the spreading of the south fiji basin and all the currently spreading basins in the southwestern pacific spreading of individual marginal basins occurred during the short period when a hot region was passing the pertinent area the main merit of this hypothesis is that it can explain the relationship between the location and age as well as the short duration of spreading of western pacific marginal basins marginal basins are formed commonly though not always in the overriding plates near subduction zones because in such a setting a spreading marginal basin is readily accommodated either by an oceanward movement of the nearby subduction zone or by a continentward movement and subduction of the overriding oceanic plate there are a few marginal basins that were formed in other tectonic settings and accommodated by some other mechanism of compensative subduction presumably the splitting of the supercontinent pangea was also caused mainly by the effect of the mantle upwelling associated with the same hot region that later migrated northward creating marginal basins in the western pacific the main basis for this presumption is the fact that the splitting of pangea was completed in the australia region in middle cretaceous time whereas the spreading of marginal basins in the western pacific began in the same australia region in the late cretaceous immediately following

scattering of internal waves at finite topography in two dimensions part i theory and case studies abstract the scattering of internal gravity waves at finite topography in two dimensions is studied theoretically and numerically for a finite depth ocean a formal solution is derived using a mapping function based on ray tracing the solution satisfies radiation conditions energy is conserved the incoming energy flux is redistributed in physical and modenumber space numerical solutions are calculated for a single plane wave propagating from the ocean side onto slope shelf configurations where a flat shallow shelf is connected to a flat deep ocean by linear slopes staircases convex or concave parabolic profiles and half cosine slopes the fraction of the incoming energy flux transmitted onto the shelf and reflected back to the deep ocean and the distribution of these fluxes in modenumber space are calculated the results depend on the parameters of the incident wave and of the topography especially important is the distinction between supercritical topography where the slope of the topography exc

modelling floodplain flows using a two dimensional finite element model a prototype two dimensional finite element flow model for depth averaged free surface flows was developed for floodplain environments limited refinement of the model s physical representation was undertaken and the enhanced scheme applied to an 11 km river channel floodplain reach in the u k preliminary model results indicate that this modelling approach can be used to identify dynamic variations in the flow field parameters over length scales of the order of 10 100 m potentially such data have the ability to permit detailed analysis of short term floodplain sedimentary dynamics

geochemistry and origins of ueno and on take basaltic to andesitic rocks 3 ma produced by distinct contributions of subduction components central japan abstract ueno basaltic rocks 2 7 1 6 ma and on take volcanic rocks 0 75 ma crop out in a restricted area in central japan and were analyzed for major and trace elements and sr and nd isotopes the ueno rocks were erupted as numerous monogenetic volcanoes largely of basaltic compositions whereas the on take lavas form a composite stratovolcano dominated by andesites the ueno basalts are primarily geochemical mixtures of two components 1 sub alkalic common basalts generated from the lithospheric subcontinental mantle with 87sr 86sr 0 706 end 2 and k nb 1000 and 2 rare within plate basalts wpb of alkali basaltic composition with 87sr 86sr 0 705 end 5 k nb 180 subordinate ueno andesites were formed by assimilation fractional crystallization processes within the lower crust having 87sr 86sr 0 709 end 8 but without appreciable assimilation in the upper crust on the other hand the on take basalts have 87sr 86sr 0 705 0 0005 end 2 1 k nb 1200 and geochemical signatures characteristic of continental arc basalts the on take andesites appear to have been contaminated frequently by upper crustal materials it is proposed that the injection of a wpb type diapir yielded partial melting of the subcontinental mantle forming the common ueno basalt magmas the arc type basaltic magmatism which was probably the result of subduction of the pacific plate occurred at 1 ma after the ueno volcanism addition of slab derived components with 87sr 86sr 2300 modified the subcontinental mantle forming the source of on take basalts

riffle pool maintenance and flow convergence routing observed on a large gravel bed river abstract geomorphologists have studied and debated over the processes responsible for natural riffle pool maintenance for decades most studies have focused on small wadable rivers but they lack much description of overbank flood conditions or a spatially explicit characterization of morphodynamics in this study 1 m horizontal resolution digital elevation models were collected from a riffle pool run sequence before and after an overbank flood with a 7 7 year recurrence interval on the relatively large gravel bed lower yuba river california digital elevation model differencing was used to quantify the magnitude and pattern of flood induced morphodynamic change cross section based analysis and two dimensional hydrodynamic modeling of flows ranging from 0 147 to 7 63 times bankful discharge were completed to evaluate the hydraulic mechanisms responsible for the observed topographic changes one key finding was that riffle pool relief increased by 0 42 m confirming the occurrence of natural hydrogeomorphic maintenance spatially complex patterns of scour and deposition exceeding 0 15 m at the scale of subwidth morphological units were reasonably predicted by the two dimensional mechanistic model that accounts for convective acceleration the one dimensional cross section based method underperformed the two dimensional model significantly consequently multiple scales of channel non uniformity and a dynamic flow regime caused the observed maintenance of the pool riffle morphology through the mechanism of flow convergence routing proposed by macwilliams et al macwilliams m l wheaton j m pasternack g b kitanidis p k street r l 2006 the flow convergence routing hypothesis for riffle pool maintenance in alluvial rivers water resources research 42 w10427 doi 10 1029 2005wr004391

effects of lidar derived spatially distributed vegetation roughness on two dimensional hydraulics in a gravel cobble river at flows of 0 2 to 20 times bankfull abstract the spatially distributed effects of riparian vegetation on fluvial hydrodynamics during low flows to large floods are poorly documented drawing on a lidar derived meter scale resolution raster of vegetation canopy height as well as an existing algorithm to spatially distribute stage dependent channel roughness this study developed a meter scale two dimensional hydrodynamic model of 28 3 km of a gravel cobble bed river corridor for flows ranging from 0 2 to 20 times bankfull discharge with and without spatially distributed vegetation roughness results were analyzed to gain insight into stage dependent and scale dependent effects of vegetation on velocities depths and flow patterns at the floodplain filling flow of 597 49 m 3 s adding spatially distributed vegetation roughness parameters caused 8 0 and 7 4 increases in wetted area and mean depth respectively while mean velocity decreased 17 5 vegetation has a strong channelization effect on the flow increasing the difference between mid channel and bank velocities it also diverted flow away from densely vegetated areas on the floodplain vegetation stands caused high velocity preferential flow paths that were otherwise unaccounted for in the unvegetated model runs for the river as a whole as discharge increases overall roughness increases as well contrary to popular conception

the formation and fate of internal waves in the south china sea internal oceanic waves are subsurface gravity waves that can be enormous and travel thousands of kilometres before breaking but they are difficult to study here observations of such waves in the south china sea reveal their formation mechanism extreme turbulence relationship to the kuroshio current and energy budget internal waves are the underwater version of more familiar surface waves they can be enormous and travel thousands of kilometres before breaking the south china sea is known to be home to the largest internal waves in the world s oceans but their size generation mechanisms and role in the regional energy budget are unknown matthew alford and colleagues now present the results from the iwise observational campaign and reveal that internal waves more than 200 metres high break in the south china sea and create turbulence that is orders of magnitude larger than in the open ocean and that wave formation is influenced by the kuroshio current these results now allow for a complete energy budget of the south china sea and for a more accurate incorporation of internal waves into climate models internal gravity waves the subsurface analogue of the familiar surface gravity waves that break on beaches are ubiquitous in the ocean because of their strong vertical and horizontal currents and the turbulent mixing caused by their breaking they affect a panoply of ocean processes such as the supply of nutrients for photosynthesis1 sediment and pollutant transport2 and acoustic transmission3 they also pose hazards for man made structures in the ocean4 generated primarily by the wind and the tides internal waves can travel thousands of kilometres from their sources before breaking5 making it challenging to observe them and to include them in numerical climate models which are sensitive to their effects6 7 for over a decade studies8 9 10 11 have targeted the south china sea where the oceans most powerful known internal waves are generated in the luzon strait and steepen dramatically as they propagate west confusion has persisted regarding their mechanism of generation variability and energy budget however owing to the lack of in situ data from the luzon strait where extreme flow conditions make measurements difficult here we use new observations and numerical models to 1 show that the waves begin as sinusoidal disturbances rather than arising from sharp hydraulic phenomena 2 reveal the existence of 200 metre high breaking internal waves in the region of generation that give rise to turbulence levels 10 000 times that in the open ocean 3 determine that the kuroshio western boundary current noticeably refracts the internal wave field emanating from the luzon strait and 4 demonstrate a factor of two agreement between modelled and observed energy fluxes which allows us to produce an observationally supported energy budget of the region together these findings give a cradle to grave picture of internal waves on a basin scale which will support further improvements of their representation in numerical climate predictions

sensitivity of simulated flow fields and bathymetries in meandering channels to the choice of a morphodynamic model morphodynamic models are used by river practitioners and scientists to simulate geomorphic change in natural and artificial river channels it has long been recognized that these models are sensitive to the choice of parameter values and proper calibration is now common practice this paper investigates the less recognized impact of the choice of the model itself all morphodynamic models purport to simulate the same flow and sediment dynamics often relying on the same governing equations yet in solving these equations the models have different underlying assumptions for example regarding spatial discretization turbulence sediment inflow lateral friction and bed load transport these differences are not always considered by the average model user who might expect similar predictions from calibrated models here a series of numerical simulations in meandering channels was undertaken to test whether six morphodynamic codes basement cche 2d nays ssiim 1 telemac 2d and telemac 3d would yield significantly different equilibrium bathymetries if subjected to identical initial flow conditions we found that despite producing moderately similar velocity patterns on a fixed flat bed regression coefficient r of 0 77 0 20 the codes disagree substantially with respect to simulated bathymetries r 0 49 0 31 we relate these discrepancies to differences in the codes assumptions results were configuration specific i e codes that perform well for a given channel configuration do not necessarily perform well with higher or lower sinuosity configurations finally limited correlation is found between accuracy and code complexity the inclusion of algorithms that explicitly account for the effects of local bed slope and channel curvature effects on transport magnitude and direction does not guarantee accuracy the range of solutions obtained from the evaluated codes emphasizes the need for carefully considering the choice of code we recommend the creation of a central repository providing universal validation cases and documentation of recognized fluvial codes in commonly studied fluvial settings copyright 2015 john wiley sons ltd

plio pleistocene arc magmatism controlled by two overlapping subducted plates central japan abstract the plio pleistocene volcanoes of the ryohaku hida mountains of central japan have been dated using the k ar method and newly determined ages of 65 lava flows and two pyroclastic flow deposits are presented on the basis of temporal and spatial distribution and the nature of the lavas the volcanism of the area has been split into four stages 1 an early eruptive stage 5 0 2 7 ma of the e w trending kuzuryu volcanic chain of stratovolcanoes 2 the ueno basalts and genetically related rocks which formed monogenetic volcanoes and large scale rhyolite pyroclastic flows during the 2 7 1 6 3 a late eruptive stage 1 5 0 8 ma of the kuzuryu volcanic chain and 4 n s trending andesite dacitic volcanism of the hakusan 0 6 0 ma and the norikura volcanic chains 0 9 0 ma this volcanic evolution was controlled by the relationship between the two overlapping slabs of the philippine sea and the pacific plates which are subducting beneath the central japan arc the kuzuryu volcanic chain with its e w trend is caused by magma generation on the northward subducted slab of the philippine sea plate and the n s trending volcanic chains are caused by magma generated on the westward subducted slab of the pacific plate the change of motional direction of the philippine sea plate from northwards to west northwestwards 4 million years ago caused the disappearance of the subducted slab of the philippine sea plate which had obstructed the ascent of magmas derived from the underlying subducted slab of the pacific plate during the change in direction of movement of the philippine sea plate there was a temporary change in the stress field from compression to extension during which the second stage of volcanism consisting of monogenetic basaltic and rhyolitic volcanoes occurred

high frequency internal waves near the luzon strait observed by underwater gliders 1 tidal flow through the luzon strait produces large internal waves that propagate westward into the south china sea and eastward into the pacific underwater gliders gathered sustained observations of internal waves during seven overlapping missions from april 2007 through july 2008 a particular focus is the high frequency internal waves where the operational definition of high involves periods shorter than a glider profile taking 3 6 h internal wave vertical velocity is estimated from measurements of pressure and glider orientation through two methods 1 use of a model of glider flight balancing buoyancy and drag along the glider path and 2 high pass filtering of the observed glider vertical velocity by combining high frequency vertical velocities from glider flight with low frequency estimates from isopycnal depth variations between dives a spectrum covering five decades of frequency is constructed a map of the standard deviation of vertical velocity over the survey area shows a decay from the luzon strait into the pacific the growth of high frequency vertical velocity with propagation into the south china sea is observed through two 2 week time series stations the largest observed vertical velocities are greater than 0 2 m s 1 and are associated with displacements approaching 200 m the high frequency waves are observed at regular intervals of 1 day as they ride on diurnal tidal internal waves generated in the strait

topographic scattering of the low mode internal tide in the deep ocean we investigate the role of deep ocean topography in scattering energy from the large spatial scales of the low mode internal tide to the smaller spatial scales of higher modes the complete green function method which is not subject to the restrictions of the wkb approximation is used for the first time to study the two dimensional scattering of a mode 1 internal tide incident on subcritical and supercritical topography of any form in arbitrary stratifications for an isolated gaussian ridge in a uniform stratification large amplitude critical topography is the most efficient at mode 1 scattering and small amplitude topography scatters with an efficiency on the order of 5 10 in a nonuniform stratification with a pycnocline the results are qualitatively the same as for a constant stratification albeit with the key features shifted to larger height ratios having validated these results by direct comparison with the results of nonlinear numerical simulations and in the process demonstrated that wkb results are not appropriate for reasonable ocean predictions we proceed to use the green function approach to quantify the role of topographic scattering for the region of the pacific ocean surrounding the hawaiian islands chain to the south the line islands ridge is found to scatter 40 of a mode 1 internal tide coming from the hawaiian ridge to the north realistic small amplitude rough topography scatters 5 10 of the energy out of mode 1 for transects of length 1000 3000 km a significant finding is that compared to large extents of small amplitude rough topography a single large topographic feature along the path of a mode 1 internal tide plays the dominant role in scattering the internal tide

textural analysis and modelling of a flood deposit river severn u k samples of sediment collected from the severn floodplain between worcester and gloucester following the severe flooding in january and february 1990 were analysed for their grain size distribution the results show that most sand was deposited within 20 m of the channel bank but that fine sand may contribute to flood sediment across the width of the floodplain james 1985 numerical model of overbank sedimentation attempts to predict the transfer of sediment to the floodplain during flooding geometrical and hydraulic data relating to the severn flood are used as input for a computer program of james 1985 model the pattern of sediment concentrations predicted by the model was compared with that obtained from statistical analysis of the flood sediment the patterns were found to be similar so james 1985 model was considered to predict in a relative sense the distribution of flood sediment

structure propagation and mixing of energetic baroclinic tides in mamala bay oahu hawaii abstract large semidiurnal vertical displacements 100 m and strong baroclinic currents 0 5 m s 1 several times as large as barotropic currents dominate motions in mamala bay outside the mouth of pearl harbor hawaii during september 2002 the authors sought to characterize them with a 2 month mclane moored profiler deployment and a 4 day intensive survey with a towed ctd adcp and the research vessel r v revelle hydrographic sonar spatial maps and time series of turbulent dissipation rate diapycnal diffusivity k isopycnal displacement velocity u energy e and energy flux f are presented dissipation rate peaks in the lower 150 m during rising isopycnals and high strain and shows a factor of 50 spring neap modulation the largest k values in the western bay near a submarine ridge exceed 10 3 m2 s 1 the m2 phases of and u increase toward the west implying a westward phase velocity cp 1 m s 1 and horizontal wavelength 60 km consistent with theoretical mode 1 values these phase

reinitiation of subduction and magmatic responses in sw japan during neogene time southwestern japan during paleogene time was affected by subduction of the kula and pacifi c plates beneath the eastern margin of eurasia followed by a brief episode of transform faulting to allow the shikoku basin to open at 27 15 ma subsequent opening of the japan sea back arc basin in middle miocene time broke japan away from eurasia and sw japan rotated clockwise 45o as it drifted south 17 15 ma southward drift required subduction of the philippine sea plate beneath sw japan leading to the formation of a magmatic arc subduction of the hot shikoku basin lithosphere and spreading ridge resulted in distinctive volcanism in the sw japan forearc between 17 and 12 ma this volcanism included midoceanic ridge basalt morb like intrusions and oceanic island basalt oib type alkali basalts felsic plutons in the accretionary prism and high magnesium andesites along the setouchi forearc basin mafi c magmas in the outermost forearc originated from the subducted shikoku basin spreading ridge whereas setouchi high magnesium andesites hma may have resulted from the interaction of melts of the subducted philippine sea plate with the overlying mantle felsic magmas in the forearc resulted from melting of shimanto belt sediments caused by intrusion of hma magmas persistent rear arc volcanism was caused by upwelling asthenosphere associated with opening of the sea of japan rear arc volcanism began ca 25 ma as rift fi ll low alkali tholeiite volcanism and was replaced gradually after 12 ma by alkali basalt volcanism upwelling related alkali volcanism continues up to the present whereas forearc volcanism ceased at 12 ma the volcanic arc narrowed with time as the philippine sea slab descended and slowly cooled adakitic dacites erupted after 1 7 ma above the 100 km depth contour of the subducted philippine sea plate suggesting that melting resulted from interaction of the slab with upwelling asthenosphere interactions between upwelled rear arc asthenosphere and subduction of the hot philippine sea slab appear to have been the main controls of magmatism for the neogene sw japan arc

temperature and currents on the southern california shelf a description of the variability abstract temperature and horizontal current observations at three water depths 15 30 and 60 m over the southern california shelf are reported for four discrete periods during 1978 79 roughly corresponding to each of the principal seasons the vertical structure of temperature changes markedly during the year the water over the shelf is weakly stratified in the winter n 50 cpd but stratification is stronger in the summer n 250 cpd seasonal changes in vertically averaged temperature are comparatively unimportant long term averages of the longshore currents are to the south near the surface in all seasons with amplitudes ranging up to 10 cm s 1 in the winter during spring and summer the stratification is accompanied by shear in the vertical structure of these long term current averages with surface currents sweeping to the south but with deeper colder water flowing in the opposite direction currents fluctuating at subtidal frequencies are predominantly alongshore and are strongest durin

the generation of internal tides at the hawaiian ridge previous analyses of altimeter and acoustic data indicate that the hawaiian ridge is a significant generation site for semidiurnal m2 period internal waves owing to tidal flow over topography such waves likely play an important role connecting the dissipation of tidal energy to ocean mixing here a primitive equation numerical model with realistic stratification bathymetry and tidal forcing is used to simulate the generation of these waves in a manner consistent with altimeter sea surface observations the highest amplitude waves originate at three generation sites located at both the island and seamount portions of the chain these sites have in common both enhanced flows across ridge shaped topography and maxima in model calculated body force which couples barotropic and baroclinic motions the model vertical structure suggests the presence of multiple dynamical modes within 100 km of the ridge and not just the lowest modes that have been detected at the sea surface

a coupled model for laplace s tidal equations in a fluid with one horizontal dimension and variable depth abstracttide topography interactions dominate the transfer of tidal energy from large to small scales at present it is poorly understood how low mode internal tides reflect and scatter along the continental margins here the coupling equations for linear tides model celt are derived to determine the independent modal solutions to laplace s tidal equations lte over stepwise topography in one horizontal dimension celt is i applicable to arbitrary one dimensional topography and realistic stratification without requiring numerically expensive simulations and ii formulated to quantify scattering because it implicitly separates incident and reflected waves energy fluxes and horizontal velocities obtained using celt are shown to converge to analytical solutions indicating that flat bottom modes which evolve according to lte are also relevant in describing tides over sloping topography the theoretical framework presented can then be used to quantify simultaneous incident and reflected energy fl

investigating the behaviour of two dimensional finite element models of compound channel flow this paper describes results from a recent study concerning the numerical modelling of compound channel flow using two generalized two dimensional finite element codes specifically adapted to floodplain studies rma 2 and telemac 2d by application to an 11 km reach of the river culum devon uk simulations are developed to investigate the impact of numerical technique mesh resolution and topographic parameterization on model results the research is shown to raise a number of issues concerning the construction calibration and validation of two dimensional finite element models for this flow problem 1997 by john wiley sons ltd

large scale floodplain modelling a two dimensional horizontal finite element numerical model rma 2 was applied to a 24 km river channel floodplain reach in west germany initial results indicate that finite element schemes may successfully estimate inundation in large scale floodplain applications potentially the resulting detailed velocity vector distributions and identification of inundation zones throughout storm events could provide an insight into the present day sedimentary environment on the floodplain

modelling geomorphic response to environmental change in an upland catchment in the uk s upland catchments river terraces and alluvial features indicate a history of periodic aggradation and degradation linked to holocene changes in land use primarily deforestation and climate change altering flood frequency and magnitude although both factors are important calculating their individual effects is complicated by the likelihood of their concurrent alteration to investigate the relative impacts of land use and climate change a cellular model is applied to the upland catchments of cam gill beck above starbotton north yorkshire this is divided into 1 million 2 m by 2 m grid cells to which a range of process laws are applied these include approximate expressions for mass movement rates soil creep the influence of vegetation and hillslope hydrology as well as fluvial erosion and deposition in ten grain size fractions this provides a good representation of valley floor geometry while retaining a fully dynamic interaction with the surrounding valley sides previous applications of this model have shown the detailed formation of bars and berms as well as examples of braiding avulsion and channel range running on a silicon graphics origin 2000 computer an ensemble of simulations were completed bracketing a wide range of environmental scenarios involving changes in flood frequency magnitude and vegetation cover over time scales ranging from 10 to 100 years these showed that decreasing tree cover and increasing rainfall magnitude individually produced similar 25 to 100 increases in sediment discharge whereas in combination they generated a 1300 rise furthermore channels formed by the model in response to increased rainfall magnitudes are located where relic channels are found in cam gill beck implying that these are the products of previous periods of high rainfall magnitudes copyright 2000 john wiley sons ltd

interference pattern and propagation of the m2 internal tide south of the hawaiian ridge abstract most of the m2 internal tide energy generated at the hawaiian ridge radiates away in modes 1 and 2 but direct observation of these propagating waves is complicated by the complexity of the bathymetry at the generation region and by the presence of interference patterns observations from satellite altimetry a tomographic array and the r p flip taken during the farfield program of the hawaiian ocean mixing experiment home are found to be in good agreement with the output of a high resolution primitive equation model simulating the generation and propagation of internal tides the model shows that different modes are generated with different amplitudes along complex topography multiple sources produce internal tides that sum constructively and destructively as they propagate the major generation sites can be identified using a simplified 2d idealized knife edge ridge model four line sources located on the hawaiian ridge reproduce the interference pattern of sea surface height and energy fl

observations of internal tides on the oregon continental slope abstracta complex superposition of locally forced and shoaling remotely generated semidiurnal internal tides occurs on the oregon continental slope presented here are observations from a zonal line of five profiling moorings deployed across the continental slope from 500 to 3000 m a 24 h expendable current profiler xcp survey and five 15 48 h lowered adcp ladcp ctd stations the 40 day moored deployment spans three spring and two neap tides during which the proportions of the locally and remotely forced internal tides vary baroclinic signals are strong throughout spring and neap tides with 4 5 day long bursts of strong cross slope baroclinic semidiurnal velocity and vertical displacement energy fluxes exhibit complex spatial and temporal patterns throughout both tidal periods during spring tides local barotropic forcing is strongest and energy flux over the slope is predominantly offshore westward during neap tides shoaling remotely generated internal tides dominate and energy flux is pr

internal tide radiation from the luzon strait the m2 k1 and o1 internal tides originating in the luzon strait are investigated using the sea surface height measurements by multiple satellites ers 2 envisat topex poseidon jason 1 2 and geosat follow on a plane wave fit method is used to resolve multiple internal tides in arbitrary horizontal directions the luzon strait is an energetic internal tide generation site and radiates internal tides both westward into the south china sea scs and eastward into the western pacific wp in the scs the k1 and o1 internal tides propagate over 1600 km reaching the vietnam coast in the wp they propagate over 2500 km and arrive to the mariana ridge and guam the k1 and o1 internal tides refract toward the equator during propagation the m2 internal tides in the scs bifurcate into two beams the northwestward beam is coincident with the frequent occurrence of internal solitary waves in this region implying their causative relation the phase speeds inferred from the altimetric along beam propagation agree with the theoretical values due to the influence of the earth s rotation the k1 and o1 phase speeds decrease remarkably from high to low latitudes for the diurnal internal tides the eastward radiation is about 50 greater than the westward radiation for m2 the westward radiation is about two times the eastward radiation the altimetric energy fluxes are about 50 of those in numerical model simulations

internal tide generation by seamounts ridges and islands a numerical investigation is made into the generation of semidiurnal internal tides by tidal flow over steep topographic features in the deep ocean a fully three dimensional free surface nonlinear hydrostatic model the princeton ocean model is used with real stratification representative tidal forcing and gaussian shaped seamounts ridges and islands for the topography the efficiencies of the different topographies in extracting energy from the barotropic tide and in generating an internal tide are considered each topography produces an internal tide characterized by signals propagating away from the feature as beams that follow internal wave characteristic paths the strength of the signals however varies markedly for different topographies this is largely attributed to the way in which the barotropic tide interacts with the three dimensional topography internal wave generation requires a significant vertical displacement of stratified water by the barotropic tide as it flows over topography it is found that for symmetric seamounts and islands the barotropic flow tends to go around the feature producing only a weak internal tide when elongated into a ridge barotropic flow is forced across isobaths generating an energetic internal tide changing the horizontal aspect ratio of the topography from 1 1 a seamount to 3 1 a ridge increases the resulting baroclinic energy flux by nearly an order of magnitude the slope of the topography relative to that of the internal wave characteristics is also shown to be important with strongest generation occurring at regions of critical or supercritical topographic slope

geochemistry of miocene basaltic rocks temporally straddling the rifting of lithosphere at the akita yamagata area northeast japan abstract voluminous basaltic rocks with arc geochemical signatures were produced in the akita yamagata area the back arc side of ne japan in the middle miocene temporally straddling the opening of the japan sea eleven of these rocks were studied for trace elements among these seven whole rocks and five clinopyroxene separates were analyzed for 87 sr 86 sr and four clinopyroxene separates were analyzed for 143 nd 144 nd the results suggest that the lithosphere has been partly broken up and eliminated or thinned beneath the back arc side of ne japan since 16 ma the new analyses and existing data collectively show that the basaltic magmas have decreased in 87 sr 86 sr and increased in 143 nd 144 nd since 16 ma coincidently the magmas have changed their geochemical signature from a continental margin type to an oceanic arc type on average the basaltic rocks younger than 16 ma are likely to be products of varying degrees of mixing between subduction related basaltic magmas with low 87 sr 86 sr 0 703 0 7035 and partial melts of subarc lithospheric mantle with high 87 sr 86 sr 0 7055 at least in part and arc tholeiitic geochemical characteristics the basaltic rocks older than 16 ma seem to have been more intensely contaminated by crustal material

standing internal tides in the tasman sea observed by gliders abstractlow mode internal tides are generated at tall submarine ridges propagate across the open ocean with little attenuation and reach distant continental slopes a semidiurnal internal tide beam identified in previous altimetric observations and modeling emanates from the macquarie ridge crosses the tasman sea and impinges on the tasmanian slope spatial surveys covering within 150 km of the slope by two autonomous underwater gliders with maximum profile depths of 500 and 1000 m show the steepest slope near 43 s reflects almost all of the incident energy flux to form a standing wave starting from the slope and moving offshore by one wavelength 150 km potential energy density displays an antinode node antinode node structure while kinetic energy density shows the opposite mission mean mode 1 incident and reflected flux magnitudes are distinguished by treating each glider s survey as an internal wave antenna for measuring amplitude wavelength and direction incident fluxes are 1 4 and 2 3 k

hydrodynamic modelling of a large flood prone river system in india with limited data the article presents a detailed review on the issues and constraints of hydrodynamic modelling of floods in data poor countries with large flood prone rivers a one dimensional 1d hydrodynamic model is used to simulate the river flows with limited available data in the delta region of mahanadi river basin in india the shuttle radar topography mission digital elevation models srtm dem was analyzed and compared with the elevations derived from available topomaps and measured river cross sections subsequently the srtm derived river cross section elevation values are refined for use in the hydrodynamic model the 1d hydrodynamic model is set up and calibrated using the refined cross sections derived from srtm dem along with the measured ones and all available river discharge as well as water level data at different gauging sites for the monsoon period june september of the year 2004 the calibrated set up is validated using both discharge and water level data for the same period for the years 2001 and 2002 the performance of the calibration and validation results of the hydrodynamic model is evaluated for all the years using different performance indices the model simulated discharge and water levels are found to be in close agreement with the observed ones the study demonstrates the usefulness of using the srtm dem to derive river cross sections for use in hydrodynamic modelling studies copyright 2009 john wiley sons ltd

zonal structure of cenozoic basalts related to mantle upwelling in southwest japan cenozoic olivine bearing basaltic rocks in the central chugoku district form eight provinces each 20 to 30 km in diameter these provinces can be grouped into three zones almost parallel to the elongation of the sw japan arc based on geological and petrological characteristics the san yo zone the closest to the nankai trough is characterized by a small amount of alkaline basalt in the sekiryo zone intermediate zone transitional basalt is dominant the san in zone along the japan sea coast is characterized by subalkaline basalt and a large amount of andesitic rocks the eruption volume of these volcanics exponentially increases toward the back arc side less than 1 km3 to more than 100 km3 chemical compositions of relatively undifferentiated basalts show systematic across arc variations sio2 and al2o3increase and feo mgo and cao decrease toward the back arc side 44 to 54 13 to 18 11 to 6 13 to 7 and 12 to 8 wt at feo mgo 0 85 respectively melting experiments on the basalt h2o co2 systems show that the pressure and temperature of magma segregation decrease toward the back arc side 17 19 kbar and 1340 1320 c to 8 kbar and 1250 c and the coexisting phases change from a spinel lherzolite assemblage to a harzburgite assemblage these pt conditions define a trend which can be interpreted as a pt path for adiabatic upwelling of the mantle material consequently the observed volcanism and zonation may have been caused by upwelling of a plume from a deep part of the mantle

internal tide scattering at the line islands ridge 1 scattering of the m2 mode one internal tide from the line islands ridge is examined with a primitive equation numerical model model runs with baroclinic and barotropic forcing are performed to distinguish scattered from locally generated internal tides tpxo 5 tidal model sea surface elevations provide barotropic forcing while for the run with baroclinic forcing a mode one m2 energy flux of 1000 w m 1 is used to represent energy fluxes emanating from the hawaiian ridge scattering redistributes more energy flux from mode one than is locally generated in mode one for the higher modes scattering and generation contribute equally in terms of the overall energy flux spatial and modal distributions of energy density and flux show internal tide scattering dominates at hutchinson seamount while higher modes are generated locally at sculpin ridge hutchinson seamount s slopes are steeper over a greater continuous area than sculpin ridge scattered energy is found downstream of the steepest topographies similar to simulations with idealized gaussian ridges at the line islands ridge 37 of the incident mode one energy flux is lost because of scattering into modes 2 5 19 dissipation by the model s turbulence parameterization 15 and nonlinear transfer to the m4 internal tide 3 two topex ground tracks pass through the model domain roughly normal to the ridge topography and confirm the general features of the modal and spatial distribution found in the model in the topographically rough western pacific internal tide scattering may be a significant source of energy for mixing away from topography