mesoscale eddy variability in the southern extension of the east madagascar current seasonal cycle energy conversion terms and eddy mean properties in this study we used more than 17 years of satellite altimetry observations and output from an ocean model to investigate the mesoscale eddy variability and forcing mechanisms to the south of madagascar analysis of energy conversion terms in the model has shown seasonality on eddy formation both by barotropic and baroclinic instabilities maximum in winter jja and minimum in summer djf the eddies were mainly formed in the upper ocean 0 300 m and at intermediate depths 800 2000 m by barotropic and baroclinic instabilities respectively the former dominated in the southeastern margin of madagascar and the latter to the southwest where the south east madagascar current semc separates from the continental shelf seasonality of the eddy formation appeared linked with the seasonal intensification of the semc the energy conversion terms indicated that the eddies have a significant contribution to the large scale circulation but not being persistent throughout the year occurring mainly during the fall season mam eddy demography from altimetry and model provided information on eddy preferential sites for birth annual occurrence 6 13 per year eddy mean diameter 124 178 km mean amplitude 9 28 cm life time 90 183 days and maximum traveling distances 325 1052 km eddies formed to the southwest of madagascar exhibited distinct characteristics from those formed in the southeast nevertheless all eddies were highly nonlinear suggesting that they are potential vectors of connectivity between madagascar and africa this may have a significant impact on the ecology of this region

petrology of alkali basalts of zlot timok magmatic complex eastern serbia abstract alkali basalts were discovered in the timok magmatic complex only in a borehole near zlot they are composed of plagioclase and clinopyroxene phenocrysts lying in intersertal to pilotaxitic groundmass the characteristic feature of these rocks is the high content of needle shaped magnetite various disequilibrium features in alkali basalt of zlot reflect complex convection effects and recharge most probably in a shallow magma chamber major and trace elements data indicate that alkali basalts of zlot originated from magmas deriving from metasomatized mantle wedge above a subducting and dehydrating plate however the investigated rocks did not originate from primary magmas but from a magma which has undergone considerable fractional crystallization

regional setting and geochronology of the late cretaceous banatitic magmatic and metallogenetic belt the 1 500 km long banatitic magmatic and metallogenetic belt bmmb of romania serbia and bulgaria is a complex calc alkaline magmatic arc of late cretaceous age it hosts a variety of magmatic hydro thermal cu au mo zn pb and fe deposits including europe s only world class porphyry copper deposits regional metallogeny can be linked to subduction of the vardar ocean during the late cretaceous as part of the closure of the neotethys ocean that had separated europe and africa in the mesozoic porphyry cu au mo and intimately associated epithermal massive sul phides dominate in the central segments of the belt in southernmost banat romania serbia and north west bulgaria these districts are the economically most im portant today including major active cu au mines at moldova noua in romania majdanpek veliki krivelj and bor in serbia and elatsite assarel and chelopech in bulgaria more numerous and mostly mined in the past are fe cu and zn pb skarns which occur mainly at the two ends of the belt in eastern bulgaria and in romania this paper summarises some of the deposit characteristics within the geodynamic framework of terminal vardar subduction heterogeneous terranes of the belt including the apuseni mountains at the western end are aligned parallel to the vardar front following continental collision of the dacia and tisza blocks all available geochronological data numerous k ar and some u pb and re os ages are compiled and are complemented by a new high precision re os date for the dognecea skarn deposit south west romania 76 6 0 3 ma these data indicate that magmatism extended over at least 25 million years from about 90 to 65 ma in each segment of the belt within apuseni mountains and banat where magma emplacement was related to syn collisional extension in the orogenic belt of carpathians ore formation seems to be restricted in time and maybe constrained by a shared tectonic event

700 ma rift event in the blue ridge province of virginia a unique time constraint on pre iapetan rifting of laurentia discovery of compositionally distinctive rhyolites produced from a peralkaline volcanic center within the late neoproterozoic robertson river batholith and which are intercalated with terrestrial deposits of the previously undated mechum river formation indicates that rift related sedimentation and magmatism were ongoing at 702 705 ma about 130 m y before the breakup of laurentia recognition of late neoproterozoic age rhyolites in central virginia indicates that rift related magmatism was more widespread along the incipient eastern present coordinates margin of laurentia than previously thought neoproterozoic rifting in the blue ridge province of virginia appears to have been part of a broad scale process that affected most if not all of the preserved margins of laurentia the association of similar extension related terrestrial deposits and compositionally distinctive felsic rocks elsewhere may provide a unique marker for testing proposed predrift configurations of the late neoproterozoic supercontinent rodinia

horizontal and vertical structure of easterly waves in the pacific itcz abstract outgoing longwave radiation olr and low level wind fields in the atlantic and pacific intertropical convergence zone itcz are dominated by variability on synoptic time scales primarily associated with easterly waves during boreal summer and fall this study uses spectral filtering of observed olr data to capture the convective variability coupled to pacific easterly waves filtered olr is then used as an independent variable to isolate easterly wave structure in wind temperature and humidity fields from open ocean buoys radiosondes and gridded reanalysis products the analysis shows that while some pacific easterly waves originate in the atlantic most of the waves appear to form and strengthen within the pacific pacific easterly waves have wavelengths of 4200 5900 km westward phase speeds of 11 3 13 6 m s 1 and maximum meridional wind anomalies at about 600 hpa a warm moist boundary layer is observed ahead of the waves with moisture lofted quickly through the troposphere by deep co

upper ocean eddy heat flux across the antarctic circumpolar current in drake passage from observations time mean and seasonal variability abstracteddy heat flux plays a fundamental role in the southern ocean meridional overturning circulation providing the only mechanism for poleward heat transport above the topography and below the

moored observations of the current and temperature structure over the continental slope off central california 2 the energetics of the flow off point sur the data from two current meter moorings off point sur california were analyzed to examine the energy transfers over the continental slope in the california current system ccs the method used was to calculate terms in the heat equation at intermediate depths between instruments using the thermal wind relation to estimate the horizontal temperature gradients from the vertical shear time series of u v and t were collected for 17 months may 1989 to october 1990 at site p2 on the 800 m isobath and for 12 months may 1990 to may 1991 at site p3 25 km farther offshore on the 1800 m isobath instrument depths were 100 350 and 500 m at both moorings plus 1000 m at site p3 mean values of the energy conversion terms were computed at sites p2 and p3 at 225 m depth and at site p2 at 425 m depth the local change of eddy potential energy epe was approximately balanced epe t 0 for each case but the dynamics were quite different at p2 225 the sources of epe were advection by the mean flow and baroclinic instability which converted mean potential energy mpe to epe the losses came from eddy advection out of the region and the vertical eddy heat flux vehf which converted epe to eddy kinetic energy eke at p2 425 baroclinic instability provided the major source of epe this plus a small positive contribution from the vehf was balanced by advection of epe out of the region by both the mean flow and the eddies at p3 225 mean advection and baroclinic instability were negligible and the downward eddy heat flux vehf was balanced by advection of heat out of the region by the eddies time series of terms in the epe equation were used to examine high energy transfer events at both moorings events at p2 involved both horizontal and vertical processes and had longer timescales several days to weeks than those at p3 which had much shorter timescales 2 5 days and were dominated by vertical processes compared to the gulf stream the mean baroclinic instability at p2 both depths was smaller by at least a factor of 10 a term by term comparison between the mean values off point sur and the kuroshio extension showed different processes with the eddies gaining strength at the expense of the mean flow off point sur and the opposite occurring in the kuroshio extension

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

gulf stream meander propagation past cape hatteras the propagation and growth characteristics of gulf stream meanders past the stream s separation point at cape hatteras are analyzed using yearlong time series from a mooring program sponsored by the minerals management service which included moorings imbedded in the gulf stream cyclonic flank both upstream south and downstream north of cape hatteras in the upstream region energetic meanders of 3 8 day period 180 380 km wavelength propagate downstream along the gulf stream at speeds of 40 55 km day 21 this variability decays almost completely across the gulf stream separation with growth in lower frequency variability 30 120 day in the downstream direction wavelength and phase speed in the 3 8 day band are strong functions of frequency with increasing phase speed for increasing wavenumber phase speeds upstream from cape hatteras and across the gulf stream separation point are faster for a given wavenumber than downstream from cape hatteras in keeping with prior published estimates at the upstream end of the study site both baroclinic and barotropic mechanisms contribute to the decay of 3 8 day meanders and growth of lower frequency 30 120day variability in the downstream direction at the downstream end of the study region the reverse holds with both baroclinic and barotropic mechanisms contributing to growth of 3 8 day meanders and decay of lowerfrequency 30 120 day variability

southern ocean overturning compensation in an eddy resolving climate simulation the southern ocean s antarctic circumpolar current acc and meridional overturning circulation moc response to increasing zonal wind stress is for the first time analyzed in a high resolution 0 1 ocean and 0 25 atmosphere fully coupled global climate simulation using the community earth system model results from a 20 yr wind perturbation experiment where the southern hemisphere zonal wind stress is increased by 50 south of 30 s show only marginal changes in the mean acc transport through drake passage an increase of 6 136 144 sverdrups sv 1 sv 10 6 m 3 s 1 in the perturbation experiment compared with the control however the upper and lower circulation cells of the moc do change the lower cell is more affected than the upper cell with a maximum increase of 64 versus 39 respectively changes in the moc are directly linked to changes in water mass transformation from shifting surface isopycnals and sea ice melt giving rise to changes in surface buoyancy forcing the increase in transport of the lower cell leads to upwelling of warm and salty circumpolar deep water and subsequent melting of sea ice surrounding antarctica the moc is commonly supposed to be the sum of two opposing components a wind and transient eddy overturning cell here the transient eddy overturning is virtually unchanged and consistent with a large scale cancellation of localized regions of both enhancement and suppression of eddy kinetic energy along the mean path of the acc however decomposing the time mean overturning into a time and zonal mean component and a standing eddy component reveals partial compensation between wind driven and standing eddy components of the circulation

prevalence of strong bottom currents in the greater agulhas system deep current meter data and output from two high resolution global ocean circulation models are used to determine the prevalence and location of strong bottom currents in the greater agulhas current system the two models and current meter data are remarkably consistent showing that benthic storms with bottom currents greater than 0 2 m s 1 occur throughout the agulhas retroflection region south of africa more than 20 of the time furthermore beneath the mean agulhas current core and the retroflection front bottom currents exceed 0 2 m s 1 more than 50 of the time while away from strong surface currents bottom currents rarely exceed 0 2 m s 1 implications for sediment transport are discussed and the results are compared to atmospheric storms benthic storms of this strength 0 2 m s 1 are comparable to a 9 m s 1 beaufort 5 windstorm but scaling shows that benthic storms may be less effective at lifting and transporting sediment than dust storms

meridional transport across a zonal channel topographic localization experiments are performed using a two layer isopycnic numerical model in a zonal channel with a large meridional topographic ridge in the lower layer the model is forced only by a steady meridional volume transport in the upper layer and develops a current structure similar to the antarctic circumpolar current meridional volume flux across time mean geostrophic streamlines is found to be due to a combination of the geostrophic eddy bolus flux and the lateral reynolds stress the proportion of each depends on the strength of the forcing the reynolds stress increases with the forcing while the bolus flux is relatively constant topography localizes the eddy fluxes at and downstream of the topography where eddy energies are greatest the strength of the zonal transport is governed by the onset of baroclinic instability and so is relatively insensitive to the strength of the meridional transport

glacially influenced sedimentation in the late neoproterozoic mechum river formation blue ridge province virginia the late neoproterozoic ca 700 730 ma mechum river formation is exposed as a structural inlier within grenvillian basement in the blue ridge province of central virginia united states the southern portion of the mechum river belt preserves evidence of glaciomarine sedimentation at the margin and basinward of grounding line fans subaqueous glacial till coarse grained rhythmites and dropstones record the incursion of ice into the basin marine deposition is evidenced by persistent laminations cyclopsams in rhythmically bedded diamictite and possibly by tidally pumped distal turbidites in laminated mudstones glaciomarine sedimentation in the mechum river formation may have been coeval with sturtian rapitan glaciations in northwestern laurentia and australia and provides further evidence for a globally cold climate during the late neoproterozoic

late proterozoic ca 930 ma extension in eastern laurentia the northwest dipping carthage colton shear zone located near the eastern margin of the grenville province in northern new york separates the adirondack lowlands of the metasedimentary belt from the adirondack highlands of the granulite terrane published u pb sphene ages are 1156 1103 ma in the lowlands and 1050 982 ma in the highlands indicating an 100 m y offset in metamorphic ages across the boundary our reported hornblende 40 ar39 ar ages are 1060 ma in the lowlands and 950 ma in the highlands this confirms the offsets in sphene ages across the carthage colton shear zone and indicates an average cooling rate in both the lowlands and the highlands of 18 28 m y over 100 m y biotite 40

eddy variability and energetics from direct current measurements in the antarctic circumpolar current south of australia two year time series measurements of current velocity and temperature in the subantarctic front saf south of australia from 1993 to 1995 provide estimates of eddy fluxes of heat and momentum across the antarctic circumpolar current acc and further insight into the variability of the acc the saf was found to be an energetic meandering jet with vertically coherent fluctuations varying on a timescale of 20 days with typical amplitude 30 cm s21 at 1150 dbar a daily varying coordinate frame that follows the direction of flow allowed mesoscale variability of the saf to be isolated from variability due to meandering of the front and proved very successful for examining eddy fluxes vertically averaged cross stream eddy heat flux was 11 3 kw m 22 poleward and significantly different from zero at 95 for fluctuations in the 2 90 day band zonally integrated this eddy heat flux 50 9 pw is more than large enough to balance heat lost south of the polar front and is as large as cross saf fluxes found in drake passage cross stream eddy momentum fluxes were small not significantly different from zero and of indeterminate sign but tending to decelerate the mean flow a relationship between vertical motion and meander phase identified in the gulf stream was found to hold for the acc eddy kinetic energy levels were similar to those in drake passage and southeast of new zealand eddy potential energy was up to an order of magnitude larger than at other acc sites most likely because meandering of the front is more common here baroclinic conversion was found to be the dominant mechanism by which eddies grow south of australia typical eddy growth time is estimated to be 30 days approximately twice as fast as in drake passage consistent with eddy energy growing rapidly downstream

the mechum river formation virginia blue ridge a record of neoproterozoic and paleozoic tectonics in southeastern laurentia neoproterozoic metasedimentary rocks of the mechum river formation crop out in an elongate northeast southwest trending belt in the central virginia blue ridge province the northwestern contact of the mechum river formation is nonconformable above mesoproterozoic basement whereas the southeastern contact is a set of steeply dipping brittle reverse faults that juxtapose basement against mechum river rocks the internal structure of the belt consists of northwest verging open to tight moderately to steeply plunging asymmetric folds although previous workers have interpreted the outcrop belt of the mechum river formation as a graben formed during laurentian rifting structural relations require that its present geometry is a structural inlier related to paleozoic contractional deformation strain analysis reveals that grain scale deformation processes produced up to 35 percent shortening during foliation development whereas map scale folds account for an additional 30 to 50 percent shortening restoration of the mechum river formation to its pre contractional geometry reveals little about the geometry of the original depositional basin the bounding reverse faults on the east side of the mechum river formation are interpreted as out of sequence structures that developed after regional folding metamorphism and foliation development that may be related to the emplacement of the blue ridge thrust sheet over a tectonic ramp sediment transport indicators are consistent with a source area to the east suggesting that the mechum river formation was separated from similar units in the eastern blue ridge by an asymmetric basement high that may have been produced by block rotation above listric normal faults

kinematics of the alpine west carpathian orogen and palaeogeographic implications we present the euler rotations of the plates involved in the alpine west carpathian orogen the rotations are defined to a large extent by the magnetic anomalies of the atlantic ocean a few extra rotations occurred during two collisions and a mid cretaceous event at variance with earlier reconstructions we additionally control the rotations by the orientation of palaeomagnetic declinations the plate rotations are integrated into a model illustrated by palaeogeographical maps special features of the model are 1 subdivision of the northern margin of adria into the two plates pelso and austroalpine west carpathia on the basis of palaeomagnetic data 2 eohellenic obduction of meliata units onto the eastern margins of pelso and austroalpine west carpathia from the tethys side 3 first eoalpine collision of the marginal plates of adria with tisza far off the west european plate margin 4 a 80 90 rotation of austroalpine west carpathia during the eoalpine collision 5 subdivision of the neoalpine collision into a palaeogene stage of predominantly strong se nw shortening and a neogene stage of predominantly lateral extrusion westward and eastward in principle the maps show quantitative ocean spreading subduction and plate rotations however possible modifications of the model discussed in this paper limit the quantitative evaluation

a comparison of mesoscale eddy heat fluxes from observations and a high resolution ocean model simulation of the kuroshio extension abstractfor the first time estimates of divergent eddy heat flux dehf from a high resolution 0 1 simulation of the parallel ocean program pop are compared with estimates made during the kuroshio extension system study kess the results from pop are in good agreement with kess observations pop captures the lateral and vertical structure of mean to eddy energy conversion rates which range from 2 to 10 cm2 s 3 the dynamical mechanism of vertical coupling between the deep and upper ocean is the process responsible for dehfs in pop and is in accordance with baroclinic instability observed in the gulf stream and kuroshio extension meridional eddy heat transport values are 14 larger in pop at its maximum value this is likely due to the more zonal path configuration in pop the results from this study suggest that hr pop is a useful tool for estimating eddy statistics in the kuroshio extension region and thereby provide guidance in the formulation and testing of eddy mixing parameterization schemes

circulation in drake passage revisited using new current time series and satellite altimetry 1 the yaghan basin the complex bathymetry of the drake passage and the meridional extent of the shackleton fracture zone in particular force the subantarctic front saf and the polar front pf to veer to the north and the flow of the antarctic circumpolar current concentrates in the yaghan basin we have studied the circulation in the yaghan basin using 3 years of velocity data january 2006 march 2009 at five mooring sites and 18 years of satellite altimetry data mean velocities at our mooring sites show a dominant eastward component which decreases with depth as expected with a notable exception in the center of the yaghan basin where mean velocities reveal a dominant westward component increasing with depth the mooring data suggest the existence of a permanent strong deep cyclonic circulation over the yaghan seafloor depression in the northeastern part of the yaghan basin the in situ data provide the first opportunity to compare altimetry derived velocities with high temporal resolution near surface current meter velocities in a large eddy kinetic energy environment at high latitudes globally altimetry derived velocities compare rather well with the in situ velocities at 500 m depth both in strength and direction correlations are high between the in situ velocities and the surface velocities derived from satellite altimetric data mean sea level estimates lead to reasonable mean surface velocities with however a slight underestimation of the mean velocity at the mean location of the saf on the continental slope and a more important underestimation of the westward current in the center of the yaghan basin a dominant mode of velocity variations 23 of the variance is observed both in the in situ and satellite data corresponding to a strong southward meander of the saf upstream of the mooring line and a northward meander of the pf downstream of the latter the 18 yearlong altimetry time series shows that the mode is robust and has a strong semiannual component

time mean flow as the prevailing contribution to the poleward heat flux across the southern flank of the antarctic circumpolar current a case study in the fawn trough kerguelen plateau the major mechanisms of the oceanic poleward heat flux in the southern ocean are still in debate the long standing belief stipulates that the poleward heat flux across the antarctic circumpolar current acc is mainly due to mesoscale transient eddies and the cross stream heat flux by time mean flow is insignificant this belief has recently been challenged by several numerical modeling studies which stress the importance of mean flow for the meridional heat flux in the southern ocean here this study analyzes moored current meter data obtained recently in the fawn trough kerguelen plateau to estimate the cross stream heat flux caused by the time mean flow and transient eddies it is shown that the poleward eddy heat flux in this southern part of the acc is negligible while that from the mean flow is overwhelming by two orders of magnitude this is due to the unusual anticlockwise turning of currents with decreasing depth which is associated with significant bottom upwelling engendered by strong bottom currents flowing over the sloping topography of the trough the circumpolar implications of these local observations are discussed in terms of the depth integrated linear vorticity budget which suggests that the six topographic features along the southern flank of the acc equivalent to the fawn trough case would yield sufficient poleward heat flux to balance the oceanic heat loss in the subpolar region as eddy activity on the southern flank of the acc is too weak to transport sufficient heat poleward the nonequivalent barotropic structure of the mean flow in several topographically constricted passages should accomplish the required task

strong eddy compensation for the gulf stream heat transport using a high resolution ocean model forced with high resolution atmospheric fields a 5 year mean heat budget of the upper ocean in the gulf stream gs region is analyzed the heat brought to the region with the mean flows along the gs path is 2 3 times larger than the heat loss to the atmosphere with the difference being balanced by a strong cooling effect due to lateral eddy heat fluxes however over a broad area off the grand banks the eddies warm the uppermost ocean layers partly compensating for the loss of heat to the atmosphere the upward eddy heat flux which brings heat from the deeper ocean to the upper layers is 30 80 of the surface heat loss

energetics of eddy mean flow interactions in the brazil current between 20 s and 36 s the energetics of eddy mean flow interactions in the brazil current bc between 20 s and 36 s are investigated in nineteen transects perpendicular to the 200 m isobath ten years 2000 2009 of output data from the hybrid coordinate ocean model hycom ncoda reanalysis with a spatial resolution of 1 12 5 and five day averages are used the mean kinetic energy mke and eddy kinetic energy eke fields presented the same subsurface spatial pattern but with reduced values the eke increases southward with high values along the bc path and the offshore portion of the jet the values of the barotropic conversion term btc are highest in the surface layers and decreased with depth whereas the values of the baroclinic conversion term bcc and the vertical eddy heat flux vehf are highest in the subsurface despite the vertical thickening of the bc the highest energy conversion rates are confined to the upper 700 m of the water column the energetic analysis showed that the current features mixed instability processes the vertical weighted mean of the btc and bcc presented an oscillatory pattern related to the bathymetry the eddy field accelerates the time mean flow upstream and downstream of bathymetric features and drains energy from the time mean flow over the features the bc is baroclinically unstable south of 28 s and the highest energy conversion rates occur in cabo de sao tome cabo frio and the cone do rio grande

variability in the deep western boundary current local versus remote forcing 1 horizontal velocity temperature and salinity measurements from the line w array for the period 2004 2008 show large changes in the water mass structure and circulation of the deep western boundary current dwbc fluctuations in the flow with periods from 10 to 60 days are bottom intensified signals most likely associated with topographic rossby waves trw a fraction 15 of the dwbc transport variability is caused by gulf stream rings and meanders these flow anomalies are surface intensified and fluctuate at frequencies lower than the trw interannual variability in the velocity field appears to be related to changes in the hydrographic properties the dominant mode of variability is characterized by an overall freshening cooling a potential vorticity pv increase in the deep labrador sea water dlsw and a pv decrease in the overflow water ow the variability in the flow associated with these property changes is not spatially homogeneous offshore water depths larger than 3500 m changes in the velocity are in phase with pv changes in the ow a decrease in the ow pv is accompanied by an increase in the southward negative transport conversely variations of the inshore flow are in phase with changes in the dlsw pv increasing pv and decreasing transport this trend true for most of the record reverses after the winter of 2007 2008 a sudden decrease of the dlsw pv is observed with a corresponding intensification of the flow in the inner dwbc as well as a northward shift in the gulf stream axis

cyclogenesis in the deep ocean beneath the gulf stream 1 description one of the primary scientific results of the synoptic ocean prediction synop observational program was the discovery of strong cyclones in the deep ocean beneath the large amplitude gulf stream meander troughs that routinely form at about 68 w these strong well organized cyclones extend to at least 3500 m below the sea surface and are an important component of the overall dynamical variability of the gulf stream and adjacent deep waters typically a small amplitude gulf stream meander stalls near 68 w and begins to amplify as the amplitude of troughs in the gulf stream jet increases the currents at 3500 m strengthen and turn forming a cyclonic circulation pattern during synop six well defined instances of meander trough amplification and deep cyclogenesis occurred the cyclones were characterized by strong swirl speeds up to 0 5 m s 1 and were long lived typically lasting 6 9 weeks frequent occurrences present 35 of the time during the 25 month deployment period the structure of the cyclones at 3500 m is characterized by increasing velocity from the cyclone center out to some radius of maximum velocity and decreasing velocity beyond that radius this structure was robust over the lifetime of an event and from event to event cyclone radius and the radius to maximum velocity were consistently 130 km and 55 km respectively evidence of cyclones at upper measurement levels and the low vertical shear values apparent in the deep water below the thermocline indicate that the cyclones extended throughout the entire water column from the benthic boundary layer through the thermocline and to the ocean s surface

global c cycle perturbations recorded in marbles a record of neoproterozoic earth history within the dalradian succession of the shetland islands scotland abstract the shetland islands in scotland contain a c 12 km thick mostly siliciclastic neoproterozoic succession that experienced deformation and greenschist to amphibolite facies metamorphism during the ordovician silurian caledonian orogeny correlating these rocks with neoproterozoic successions elsewhere has remained problematic however four marble units punctuate the succession these are in stratigraphic order the weisdale whiteness girlsta and laxfirth limestones two of which record hallmark c isotopic excursions diagnostic of neoproterozoic time the whiteness limestone is lithologically similar to the 635 ma marinoan post glacial cap carbonate sequence and displays a 13 c carbonate profile in which values decline from a range of 0 to 2 to a nadir of 5 and then rise towards and oscillate around 0 the girlsta limestone is a 700 900 m thick marble unit with values of 9 to 11 and is interpreted as recording the late neoproterozoic shuram wonoka event these correlations permit linking the shetland succession to neoproterozoic sections elsewhere and also show that rift related rocks in shetland post date the shuram wonoka event post c 600 ma pre c 550 ma thereby supporting the concept of a diachronous phase of extensional tectonism from c 700 ma in east central laurentia to near the close of the proterozoic in northeastern laurentia prior to the opening of the iapetus ocean

a dynamically consistent analysis of the mesoscale eddy field at the western north pacific subarctic front 1 in this study we analyze the energetics of the quasigeostrophic qg currents observed in the course of an extensive soviet field experiment in 1987 the analyzed data span over the period of 1 month and cover the region 37 5 42 5 n 151 5 158 e at an average horizontal resolution of 35 km the processed data set includes the results of measurements at 668 hydrographic stations 118 moorings geosat sea surface height anomalies ecmwf winds and etop05 bottom topography a variational data assimilation method is employed to interpolate observations onto a regular space time grid an ensemble average over optimized ocean states is utilized to estimate posterior error bars assimilation has shown that the observed mesoscale structures are well described by qg dynamics which can explain 80 85 of the variability in the velocity and density fields the model data misfits lie within the observational error bars for all the data types used in assimilation the standard laplacian type parameterization of the small scale processes was found to be inconsistent with observations as the least model data misfits were obtained with zero diffusivity coefficients analysis of the interpolated patterns revealed a pronounced mesoscale mixing event characterized by the development of a warm streamer swirling around the upper cold core of an old anticyclonic kuroshio extension eddy the process was accompanied by a fast northwestward displacement of the eddy and induced detachment of a warm elongated vortex from its eastern rim within a week the vortex penetrated northward into the subarctic zone and eventually split into several smaller scale eddies energy analysis of the optimal solution indicates that baroclinic instability is the likely source of their energy computation of energy exchanges between depth averaged and shear components of the observed currents reveals the vertical energy cascade barotropization of the shear flow at a rate of 29 4 10 7 cm2 s 3 and the weaker kinetic energy transfer of opposite sign due to topographic interaction mean currents in the region are baroclinically unstable with an estimate of the available potential energy flux from the mean current to the eddies 53 8 10 7 cm2 s 3 potential enstrophy is transferred to mesoscale at a rate of 33 7 10 19 s 3 these figures can be considered as experimental evidence of the properties of free geostrophic turbulence which were predicted by theory and observed in numerical experiments

diagnoses of an eddy resolving atlantic ocean model simulation in the vicinity of the gulf stream part ii eddy potential enstrophy and eddy potential vorticity fluxes abstract output of an eddy resolving model of the north atlantic is diagnosed in the vicinity of the gulf stream gs using quasigeostrophic potential vorticity qgpv quasigeostrophic potential enstrophy qgpe and modified divergent eddy potential vorticity flux v hq d a tongue or an elongated island of large mean qgpv along the model gs in the top 1000 m is associated with predominantly downgradient v hq d suggesting that the horizontal eddy fluxes are balancing a sink of eddy qgpe in most of the tongue or island by converting the mean qgpe into eddy qgpe some large upgradient v hq d is observed to the north of the center of the tongue or island however suggesting that some of the eddy fluxes in the northern half of the tongue or island of high qgpv are balancing a source of eddy qgpe there by converting eddy qgpe into the mean qgpe at the intermediate levels of the model under the gs eddy qgpe is small and the role of eddies appears to be mixed they are forcing the mean to some

determining geostrophic velocity shear profiles with inverted echo sounders it is known that vertical acoustic travel time round trip from the seafloor to the sea surface as measured by inverted echo sounders iess can be interpreted in terms of dynamic height this relationship is generalized and quantified in this paper for dynamic height di j integrated between a variety of pressure limits pi pj which span different portions of the main thermocline the generalized form of the di j relationships is nonlinear the conventional linear relationship is valid when the limits of integration span the entire main thermocline velocity and temperature records are shown to be highly correlated vertically indicating that the variability of the gulf stream and adjacent eddy field is dominated by the lowest baroclinic mode which is called a gravest empirical mode gem a parallel isotherms model is used to approximate the gem and to develop analytic expressions for the observed di j relationships in the gulf stream the analytic expressions represent the observations well with noise to signal variance ratios that are typically 1 using these new di j relationships the baroclinic velocity structure can be determined geostrophically by measuring the horizontal gradients with laterally separated measurements from iess baroclinic velocities determined from a two dimensional array of iess in the gulf stream during 1988 1990 agree with velocity shears directly measured by current meters the rms velocity difference between these two measurements of velocity shear at 400 dbar relative to 1000 dbar was 12 cm s 1 in the presence of typical currents of 50 cm s 1 ageostrophic motions at both mesoscale and submesoscale measured by the current meters but not by the iess contribute most of the velocity differences

a flower like glomerophyric diorite porphyry from central china constraints on the unusual texture abstract an unusual texture with plagioclase phenocrysts clustered as flower like glomerocrysts has been discovered in the wulong diorite porphyry at the southern margin of north china craton the rock consists mainly of plagioclase and amphibole with the former as dominant phenocryst two groups of the plagioclase phenocrysts have been distinguished flower like glomerocrysts fg type and single isolated phenocrysts sp type chemical compositions of both fg and sp type plagioclases are similar in anorthite contents an35 45 which are slightly higher than the matrix an25 35 calculation of the plagioclase crystallization time based on crystal size distribution csd program shows that the fg type crystals have been formed within a longer timescale 226 2782 years than the sp type crystals 98 1910 years the concave down csds and lack of small crystals for fg type plagioclases suggest that coarsening may have been involved in contrast a concave up csd within the size of 3 10 mm plagioclase indicating that a rejuvenation kinetic process after coarsening a possible formation history for the unusual flower like plagioclase glomerocrysts was proposed as follows 1 initial nucleation and growth of single crystals in a confined environment 2 ascent of early crystals with magma upwelling and radial coarsening at the roof layer of magma chamber 3 remobilization of dense crystal mush and final emplacement at shallow level of crust 4 rapid cooling and extensive nucleation and growth of matrix 5 post magmatic alteration and metamorphism it is likely that the morphologic diversity of plagioclase glomerocrysts are largely influenced by variation of undercooling degrees the second step is the most important for the formation of the flower like glomerophyric texture which requires an environments of relatively low undercooling degree

rapid eddy induced modification of subtropical mode water during the kuroshio extension system study abstractfrom 2004 to 2006 an observational array of current and pressure recording inverted echo sounders cpies were deployed as part of the kuroshio extension kex system study kess kess observed a transition from a weakly meandering stable to strongly meandering unstable state qiu and chen as the kex made this transition potential vorticity pv observed within the southern recirculation gyre srg rapidly increased from january to july 2005 in this study the authors diagnose eddy pv fluxes epvfs in isentropic coordinates within the subtropical mode water stmw layer from the cpies data to determine the role of mesoscale eddies in this rapid increase of pv the rapid increase in pv within the srg coincided with enhanced cross front epvfs and eddy pv flux convergence upstream of a mean trough in the kex path and adjacent to the srg the enhanced cross front epvfs were the result of the formation of a cold core ring ccr and the interaction of the jet with a preexisting ccr eddy d

orogenic bending around a rigid proterozoic magmatic rift beneath the central appalachian mountains abstract the transition zone between the modern northern and southern appalachian mountains is located in pennsylvania where the structural orientation of the fold and thrust belt changes from north south to east west and the orogeny narrows significantly vintage studies of wide angle reflection and temporary broadband seismic data suggest that the crust beneath the 8 km of foreland basin sequences was thickened and heavily intruded around the margins of and beneath a failed neoproterozoic rift we use receiver function analysis of broadband seismic data recorded by additional and permanent stations along with forward and inverse modeling of bouguer gravity data to constrain the geometry and depth extent of mafic intrusion and underplating in the rift as well as the role of this proterozoic heterogeneity on the location and geometry of the curvature of the appalachian orogen the receiver function analyses suggest that the crust is 47 49 km thick beneath the ancient rift about 5 7 km thicker than the surrounding area inverse models of gravity data indicate that the 300 km long zone of thickened high density crust is bounded on both the nw and se sides by steep contacts its shorter ne and sw margins are also steep contacts interpreted as crustal scale faults forward modeling of the gravity data constrained by the receiver function crustal thickness estimates sparse seismic reflection data and euler deconvolution solutions implies that the proterozoic rift has been heavily intruded as well as thickened by a 7 10 km mafic underplate its margins appear to have been sheared along ne striking fault zones that parallel appalachian thrust sheet transport directions these combined results suggest that the mid and lower crust of the proterozoic rift was enriched with pyroxene which strengthened the crust locally and localized compressional strain along its margins during the north american african collision compressional strain in the pre appalachian crystalline crust to the southwest and northeast of the proterozoic rift may have been more distributed leading to the formation of oblique slip faults orthogonal to the axes of folds and leading to the curvature in the pennsylvania salient additionally the thrust sheets are stacked most thickly in front of the rift suggesting that the rift served as a backstop during collision

eddy mean flow interaction in the gulf stream at 68 w part i eddy energetics abstract from june 1988 to august 1990 twelve tall high performance current meter moorings measured the gulf stream s velocity and temperature fields at nominal depths of 400 m 700 m 1000 m and 3500 m along three lines centered at 68 w the overall eddy variability during the 26 month experiment was dominated by six large amplitude trough formation events with each event lasting approximately one month to determine the source s of energy for this eddy variability the eddy energy budget is evaluated traditionally the baroclinic conversion of mean potential energy to eddy potential energy is defined as a downgradient heat flux however because a nondivergent heat flux can be downgradient even under conditions in which there is no barolinic conversion occurring a better more dynamically correct definition of a baroclinic conversion rate is a downgradient horizontally divergent heat flux the horizontally divergent heat flux component is estimated to be approximately half the full horizontal hea

mixed layer instabilities and restratification abstract the restratification of the oceanic surface mixed layer that results from lateral gradients in the surface density field is studied the lateral gradients are shown to be unstable to ageostrophic baroclinic instabilities and slump from the horizontal to the vertical these instabilities which are referred to as mixed layer instabilities mlis differ from instabilities in the ocean interior because of the weak surface stratification spatial scales are o 1 10 km and growth time scales are on the order of a day linear stability analysis and fully nonlinear simulations are used to study mlis and their impact on mixed layer restratification the main result is that mlis are a leading order process in the ml heat budget acting to constantly restratify the surface ocean climate and regional ocean models do not resolve the scales associated with mlis and are likely to underestimate the rate of ml restratification and consequently suffer from a bias in sea surface temperatures and ml depths in a

heat fluxes across the antarctic circumpolar current in drake passage mean flow and eddy contributions in contrast to a long standing belief observations in the antarctic circumpolar current acc show that mean velocity vectors rotate with depth thus suggesting a possible importance of the time mean flow for the local poleward heat transport the respective contributions of the eddy and mean flows to the heat flux across the acc in drake passage dp are investigated using recently acquired and historical time series of velocity and temperature from a total of 24 current meter moorings and outputs of a high resolution 1 12 model with realistic topography only 11 out of the 24 depth integrated eddy heat flux estimates are found to be significant and they are poleward model depth integrated eddy heat fluxes have similar signs and amplitudes as the in situ estimates at the mooring sites they are mostly poleward or nonsignificant with amplitude decreasing to the south the cross stream temperature fluxes caused by the mean flow at the moorings have a sign that varies with location and corresponds to the opposite of the vertical velocity estimates the depth integrated temperature fluxes due to the mean flow in the model exhibit small spatial scales and are of opposite sign to the bottom vertical velocities this suggests that the rotation of the mean velocity vectors with depth is mainly due to bottom topography the rough hilly topography in dp likely promotes the small scale vertical velocities and temperature fluxes eddy heat fluxes and cross stream temperature fluxes are integrated over mass balanced regions defined by the model transport streamlines the contribution of the mean flow to the ocean heat fluxes across the southern acc front in dp covering about 4 of the circumpolar longitudes is about four times as large as the eddy heat flux contribution and the sum of the two represent on the order of 10 of the heat loss to the atmosphere south of 60 s

a model for iapetan rifting of laurentia based on neoproterozoic dikes and related rocks geologic evidence of the neoproterozoic rifting of laurentia during breakup of rodinia is recorded in basement massifs of the cratonic margin by dike swarms volcanic and plutonic rocks and rift related clastic sedimentary sequences the spatial and temporal distribution of these geologic features varies both within and between the massifs but preserves evidence concerning the timing and nature of rifting the most salient features include 1 a rift related magmatic event recorded in the french broad massif and the southern and central shenandoah massif that is distinctly older than that recorded in the northern shenandoah massif and northward 2 felsic volcanic centers at the north ends of both french broad and shenandoah massifs accompanied by dike swarms 3 differences in volume between massifs of cover sequence volcanic rocks and rift related clastic rocks and 4 wnw orientation of the grenville dike swarm in contrast to the predominately ne orientation of other neo proterozoic dikes previously proposed rifting mechanisms to explain these features include rift transform and plume triple junction systems the rift transform system best explains features 1 2 and 3 listed here and we propose that it represents the dominant rifting mechanism for most of the laurentian margin to explain feature 4 as well as magmatic ages and geochemical trends in the northern appalachians we propose that a plume triple junction system evolved into the rift transform system a ca 600 ma mantle plume centered east of the sutton mountains generated the radial dike swarm of the adirondack massif and the grenville dike swarm and a collocated triple junction generated the northern part of the rift transform system an eastern branch of this system produced the long range dike swarm in newfoundland and a subsequent western branch produced the ca 554 ma tibbit hill volcanics and the ca 550 ma rift related magmatism of newfoundland mwr206 20 page 1

the vertical structure of eddy heat transport simulated by an eddy resolving ogcm abstract the vertical structure of meridional eddy heat transport eht of the north pacific was investigated by analyzing the results from an eddy resolving ocean general circulation model ogcm with a horizontal resolution of while comparing with previous simulation results and observation data in particular the spatial and temporal variation of the effective depth of eht he was investigated which is defined by the depth integrated eht d eht divided by eht at the surface it was found that the annual mean value of he is proportional to the eddy kinetic energy eke level at the surface in general however its seasonal variation is controlled by the mixed layer depth mld in the extratropical ocean 20 n examination of the simulated eddy structures reveals that the temperature associated with mesoscale eddies is radically modified by the surface forcing in the mixed layer while the velocity field is not and the consequent enhanced misalignment of temperature and velocity anomalies leads to

northern ancestry for the goochland terrane as a displaced fragment of laurentia the ancestral position of the goochland terrane an isolated block containing mesoproterozoic crust in the appalachian piedmont of eastern virginia during grenvillian orogenesis has direct bearing on the breakup of rodinia ages lithology geochemistry and pb and nd isotope compositions of the montpelier anorthosite and state farm gneiss of the goochland terrane allow correlation with the grenvillian roseland anorthosite and associated igneous suites of the blue ridge farther west in virginia in contrast extensive metapelites which underwent devonian metamorphism and intrusion and amphibolites of the goochland terrane lack equivalents in the blue ridge dextral slip faults which bound the goochland terrane as well as dextral faults farther north suggest large scale translation prior to late paleozoic reaccretion ages of extension related a type granitoids within the virginia blue ridge 735 680 ma suggest physical separation from compositionally similar granitoids in the goochland terrane 630 588 ma reading prong 602 ma and manhattan prong 563 ma pre iapetan restoration of the goochland terrane northeastward of the blue ridge and outboard of the reading prong accounts for its affinities to the blue ridge unique anorthosites manhattan prong abundant amphibolites and reading prong ca 600 ma magmatism thus similar to the translation of madagascar out of africa the goochland terrane was rifted from laurentia marooned in oceanic crust and then dextrally translated southward 500 km prior to late paleozoic reaccretion documentation of large scale dextral translation of eastern laurentia relative to its fragments and other cratons during the neoproterozoic and paleozoic may assist in locating far traveled pieces of the grenville orogen for reconstruction of rodinia

chemical diversity and origin of precambrian charnockitic rocks of the central pedlar massif grenvillian blue ridge terrane virginia abstract middle proterozoic rocks of the pedlar massif are comprised of varied charnockitic and granulitic lithologies representing 1150 1000 ma grenvillian metamorphic and igneous events in the central appalachians of virginia chemically and mineralogically diverse units include metaluminous to peraluminous charnockites enderbites jotunites and granulite gneisses ranging in sio2 from 47 to 79 wt relative to bulk continental crust typical charnockites are enriched by 3 6 in rb k ba lree zr and hf less enriched in ta sr p and hree and depleted in cs th ti and sc although low sio2 members have relatively high ti and p and some high sio2 units are depleted in k rb and ba the pedlar river charnockite suite prcs vesuvius megacrystic charnockite vmc nellysford granulite gneiss ngg and the lady slipper granulite gneiss lsgg exhibit common chemical signatures and trends notably evident in uniform lree enriched patterns with variable eu anomalies which reflect their derivation from a mixed protolith of volcanics and reworked volcaniclastic sediments dated at 1130 1150 ma pedlar river charnockites represent portions of deep seated granulite gneisses that were mobilized by granulite facies dehydration melting and emplaced en masse as plutons into overlying and surrounding gneisses during the grenville episode divergent ree patterns in the prcs are attributed to crystallization of quartz feldspar garnet or hree compatible mafic and accessory phases leading to complementary chemical signatures in mafic and felsic layers depletion of cs throughout the pedlar massif is attributed to its incompatibility with major mineral phases during either protolith evolution or granulite facies dehydration while dispersions in k rb sr ba and eu are due to the relative proportions of the major phases quartz k feldspar plagioclase and biotite mobility of insoluble trace elements zr hf ta and th require partial melting and crystallization of accessory mineral phases whereas sc cr and ree mobility depends on the proportions of pyroxene and garnet several leucocharnockites and other felsic rocks of the prcs show markedly elevated th values ranging from 10 to 83 ppm which complement depleted th in typical prcs units these charnockitic rocks represent low degree partial melts 1 5 from normal prcs or ngg protoliths to produce high silica magmas which separated from the main charnockitic body

40 ar 39 ar age data for andesitic magmatism and hydrothermal activity in the timok massif eastern serbia implications for metallogenetic relationships in the bor copper gold subprovince the first laser induced 40ar 39ar incremental heating mineral age data for the timok massif of the banatitic magmatic and metallogenetic belt bmmb demonstrate that the main mineralization stage at the giant majdanpek cu au mo porphyry deposit took place at 83 6 84 0 0 6 ma 2 coinciding with the later 83 1 89 0 0 6 ma stages of the first cycle of andesitic volcanism the earliest campanian age for hydrothermal activity precludes an association with the later history of the bmmb and discounts the metallogenetic role of laramide plutonism for the dated deposits

estimates of eddy heat flux crossing the antarctic circumpolar current from observations in drake passage abstractthe 4 yr measurements by current and pressure recording inverted echo sounders in drake passage produced statistically stable eddy heat flux estimates horizontal currents in the antarctic circumpolar current acc turn with depth when a depth independent geostrophic current crosses the upper baroclinic zone the dynamically important divergent component of eddy heat flux is calculated whereas full eddy heat fluxes differ greatly in magnitude and direction at neighboring locations within the local dynamics array lda the divergent eddy heat fluxes are poleward almost everywhere case studies illustrate baroclinic instability events that cause meanders to grow rapidly in the southern passage where eddy variability is weak heat fluxes are weak and not statistically significant vertical profiles of heat flux are surface intensified with 50 above 1000 m and uniformly distributed with depth below summing poleward transient eddy heat transport across the lda of 0 010 0 005 pw with the stat

dynamics of kuroshio path variations in a high resolution general circulation model 1 a long lived 2 year typical large meander lm path of the kuroshio is reproduced in a high resolution general circulation model gcm simulation with realistic topography and the life cycle formation maintenance and disappearance of the lm is studied the formation of the lm is triggered by a pair of upper layer anticyclonic and cyclonic eddies on the kuroshio with the cyclonic one on the downstream side upon reaching the western side of the shikoku basin south of japan these anomalies induce a lower layer anticyclonic eddy they enhance each other while they are carried eastward by the kuroshio specifically the southward flow on the eastern side of the lower anticyclonic eddy carries the upper cold cyclonic eddy offshore resulting in the southward deflection of the kuroshio path large meander these processes can be understood as a growth of baroclinic instability a stationary lm is established when the westward tendency caused by the beta effect owing to the large meridional displacement counterbalances the eastward tendency caused by the combination of advection and vortex induction owing to the curvature of the kuroshio path large scale disturbances from the upstream tend to strengthen the lm through baroclinic energy conversion in contrast small scale disturbances from the upstream grow locally along the meandering kuroshio front through baroclinic energy conversion they extract cold waters from the cold cyclonic eddy of the lm as they flow away to the east the horizontal extent of the cold cyclonic eddy is reduced and the meander is carried eastward since the advection effect dominates over the beta effect that weakens as a result of the smaller meridional extent

eddy mean flow interactions in the along stream development of a western boundary current jet an idealized model study a theoretical study on the role of eddy mean flow interactions in the time mean dynamics of a zonally evolving unstable strongly inertial jet in a configuration and parameter regime that is relevant to oceanic western boundary current wbc jets is described progress is made by diagnosing the eddy effect on the time mean circulation examining the mechanism that permits the eddies to drive the time mean recirculation gyres and exploring the dependence of the eddy effect on system parameters it is found that the nature of the eddy mean flow interactions in this idealized configuration is critically dependent on along stream position in particular relative to the along stream evolving stability properties of the time mean jet just after separation from the western boundary eddies act to stabilize the jet through downgradient fluxes of potential vorticity pv downstream of where the time mean jet has through the effect of the eddies been stabilized eddies act to drive the time mean recirculations through the mechanism of an upgradient pv flux this upgradient flux is permitted by an eddy enstrophy convergence downstream of jet stabilization which results from the generation of eddies in the upstream region where the jet is unstable the advection of that eddy activity along stream by the jet and the dissipation of the eddies in the region downstream of jet stabilization it is in this region of eddy decay that eddies drive the time mean recirculations through the mechanism of nonlinear eddy rectification resulting from the radiation of waves from a localized region it is found that similar mechanisms operate in both barotropic and baroclinic configurations although differences in the background pv gradient on which the eddies act implies that the recirculation driving mechanism is more effective in the baroclinic case this study highlights the important roles that eddies play in the idealized wbc jet dynamics considered here of stabilizing the jet and driving the flanking recirculations in the absence of eddy terms the magnitude of the upper ocean jet transport would be significantly less and the abyssal ocean recirculations and their significant enhancement to the jet transport would be missing altogether

application of singular vector analysis to the kuroshio large meander 1 singular vector analysis is applied to the formation of the kuroshio large meander south of japan we use a simulation run of an ocean general circulation model ogcm in which a large meander occurs as the background state singular vectors are calculated by the lanczos method in which the tangent linear and adjoint models of the ogcm are used we apply an incremental correction approach for setting up the initial perturbation and averaging for the final norm in order to get modes reflecting nonlinear physics by filtering out high frequency variations the perturbation extracted as the leading right singular vector affects the formation of the large meander most if it is set to the background state two months before when the perturbation is added it enhances an anticyclonic eddy southeast of kyushu in the upper layer which induces downwelling north of it and develops an anticyclonic eddy in the deep layer the anticyclonic eddy produces a cold anomaly at the downstream edge and produces baroclinic instability there resulting in further development of the large meander in contrast the anticyclonic eddy in the deep layer is weakened when the perturbation is subtracted the development of the cold anomaly in the deep layer is delayed and consequently the meander is not so well developed thus singular vector analysis reveals the role of the anticyclonic eddy approaching southeast of kyushu in the upper layer and indicates the importance of the anticyclonic eddy in the deep layer

jet instability over smooth corrugated and realistic bathymetry abstractthe stability of a horizontally and vertically sheared surface jet is examined with a focus on the vertical structure of the resultant eddies over a flat bottom the instability is mixed

faroe bank channel overflow mesoscale variability abstractthe faroe bank channel is the deepest connection through the greenland scotland ridge where dense water formed north of the ridge flows southward over the sill crest contributing to the formation of north atlantic deep water the overflow region is characterized by high mesoscale variability and energetic oscillations accompanied by a high degree of sea surface level variability here 2 month long time series of velocity and temperature from 12 moorings deployed in may 2008 are analyzed to describe the oscillations and explore their generation and propagation the observed 2 5 5 day oscillations in velocity and temperature are highly coherent both horizontally and vertically and they are associated with 100 200 m thick boluses of cold plume water flowing along the slope a positive correlation between temperature and relative vorticity and the distribution of clockwise counterclockwise rotation across the slope suggest a train of alternating warm cyclonic and cold anticyclonic eddies where t

energetics of eddy mean flow interactions in the gulf stream region a detailed energetics analysis of the gulf stream gs and associated eddies is performed using a highresolution multidecadal regional ocean model simulation the energy equations for the time mean and timevaryingflowsarederivedasatheoreticalframeworkfortheanalysis theeddy meanflowenergycomponents and their conversions show complex spatial distributions in the along coast region the cross stream and cross bump variations are seen in the eddy mean flow energy conversions whereas in the off coast region a mixed positive negative conversion pattern is observed the local variations of the eddy mean flow interaction are influenced by the varying bottom topography when considering the domain averaged energetics theeddy meanflowinteractionshowssignificantalong streamvariability upstreamofcapehatteras the energy is mainly transferred from the mean flow to the eddy field through barotropic and baroclinic instabilities upon separating from the coast the gs becomes highly unstable and both energy conversions intensify when the gs flows into the off coast region an inverse conversion from the eddy field to the mean flow dominates the power transfer for the entire gs region the mean current is intrinsically unstable and transfers 28 26gw of kinetic energy and 26 80gw of available potential energy to the eddy field the mesoscaleeddykineticenergyisgeneratedbymixedbarotropicandbaroclinicinstabilities contributing28 26 and 9 15gw respectively beyond directly supplying the barotropic pathway mean kinetic energy also provides 11 55gw of power to mean available potential energy and subsequently facilitates the baroclinic instability pathway

divergent eddy heat fluxes in the kuroshio extension at 144 148 e part i mean structure the kuroshio extension system study kess provided 16 months of observations to quantify eddy heat flux ehf from a mesoscale resolving array of current and pressure equipped inverted echo sounders cpies the mapped ehf estimates agreed well with point in situ measurements from subsurface current meter moorings geostrophic currents determined with the cpies separate the vertical structure into an equivalent barotropic internal mode and a nearly depth independent external mode measured in the deep ocean as a useful by product of this decomposition the divergent ehf dehf arises entirely from the correlation between the external mode and the upper ocean thermal front ehfs associated with the internal mode are completely rotational dehfs were mostly downgradient and strongest just upstream of a mean trough at 1478e the downgradient dehfs resulted in a mean to eddy potential energy conversion rate that peaked midthermocline with a magnitude of 10 3 10 23 cm 2 s 23 and a depth averaged value of 3 3 10 23 cm 2 s 23 dehfs were vertically coherent with subsurface maxima exceeding 400kwm 22 near 400 m depth the subsurface maximum dehfs occurred near the depth where the quasigeostrophic potential vorticitylateralgradientchangessignfromonelayertothenextbelowit thesteeringlevelisdeeperthanthis depth of maximum dehfs a downgradient parameterization could be fitted to the dehf vertical structure with a constant eddy diffusivity k that had values of 800 1400m 2 s 21 along the mean path the resulting divergent meridional eddy heat transport across the kess array was 0 05 pw near 35 258n which may account for 1 3 of the total pacific meridional heat transport at this latitude

divergent eddy heat fluxes in the kuroshio extension at 144 148 e part ii spatiotemporal variability the kuroshio extension system study kess provided 16 months of observations to quantify divergent eddy heat flux dehf from a mesoscale resolving array of current and pressure equipped inverted echo sounders kess observations captured a regime shift from a stable to unstable state there is a distinct difference in the spatial structure of dehfs between the two regimes the stable regime had weak downgradient dehfs the unstable regime exhibited asymmetry along the mean path with strong downgradient dehfs upstream of a mean trough at 1478e the spatial structure of dehfs resulted from episodic mesoscale processes the first 6 months were during the stable regime in which fluxes were associated with eastward propagating 10 15 day upper meanders after 6 months the kuroshio extension underwent a regime shift from a stable to unstable state this regime shift corresponded with a red shift in mesoscale phenomena with the prevalence of 40 day deep externally generated eddies dehf amplitudes more than quadrupled during the unstable regime cold core ring ccr formation ccr jet interaction and coupling between 40 day deep eddies were responsible for asymmetry in downgradient fluxes in the mean maps not observed during the stable regime the kuroshio extension has prominent deep energy associated with externally generated eddies that interact with the jet to drive some of the biggest dehf events these eddies play an important role in the variability of the jet through eddy mean flow interactions the dehfs that result from vertical coupling act in accordance with baroclinic instability the interaction is not growth from an infinitesimal perturbation but from the start is a finite amplitude interaction

trace element and isotope sr nd geochemistry of porphyry and skarn mineralising late cretaceous intrusions from banat western south carpathians romania geochemical and isotopic strontium neodymium data have been obtained from 24 samples of seven late cretaceous intrusions associated with skarn tincova bocsa ocna de fier dognecea and porphyry copper molybdenum skarn deposits oravi a ciclova sasca and moldova nou in the south carpathians of romania the intrusions cut the supragetic getic nappes and form a 100 km long nne ssw trending lineament in the banat metallogenic province the samples range in composition from gabbro to granodiorite and define in major and trace element variation diagrams a calc alkaline to high potassium calc alkaline trend ranging from 50 to 67 sio2 they are magnetite bearing i type granitoids enriched in lile lree and depleted in nb ta and zr common features for magmas associated with subduction zones the lack of cumulate textures and of positive europium anomalies seems to indicate that the samples represent liquid compositions the observed trend thus approximates a liquid line of descent resulting from fractional crystallisation of parental magmas with similar major and trace element compositions initial strontium isotopic ratios sri vary from 0 7042 to 0 7058 and end t values range from 3 9 to 0 2 variations of sri and end t values with sio2 show minor crustal assimilation the generally positive end t values together with moderate sri indicate that the parental magmas result from partial melting of a rubidium enriched and lree depleted source such as a heterogeneous lithospheric mantle or a young mafic lower crust derived from it selective rubidium enrichment probably occurred during a previous subduction event by metasomatism of the overlying mantle wedge either in the early cretaceous or earlier as suggested by tdm model ages ca 600 ma the cu mo pb zn fe deposits are intimately associated with the intrusions and the banat romania region can be subdivided in two metallogenic zones in northern banat fe cu pb zn skarns occur whereas in southern banat porphyry style copper and molybdenum deposits predominate these differences result from a combination of several parameters 1 magma composition whereby copper and molybdenum rich deposits tend to be associated with calc alkaline compositions 2 an increase of the present day erosion level from south to north as indicated by the presence of large equigranular plutons in northern banat and of porphyritic cupolas and apophyses associated with porphyry style mineralisation in southern banat 3 the nature of the host rocks with skarns preferentially developed in calcareous host rocks and 4 local variations of conditions controlling the infiltration of fluids and the precipitation of ore minerals

jet streaks in the gulf stream mesoscale alongstream speed changes of the gulf stream are diagnosed from an array of current meters at depths 400 700 and 1000 m near 688w during the development of steep ratio of amplitude to wavelength o 1 meanders speed maxima jet streaks are generally found between trough and crest axes in steep meanders with local speed minima near the trough and crest axes speed changes along streamlines can be quite dramatic speed changes along the jet axis between jet streaks and local minima in excess of 0 60 0 40 and 0 35 m s 21 are observed at depth 400 700 and 1000 m respectively this is in comparison with peak speeds in a frontal coordinates system mean of 1 22 0 67 and 0 28 m s21 at depth 400 700 and 1000 m respectively from a previous study the presence of the jet streaks can be explained kinematically as a superposition of the gulf stream and barotropic vortices the development of these jet streaks in relation to the developing steep meanders differs from the canonical picture of jet streak baroclinic wave development in the atmospheric jet stream in that the jet streaks in the gulf stream are predominantly fixed in place with respect to meanders as they steepen