late ordovician jaw bearing polychaetes from anticosti island eastern canada and their biogeographic significance the upper ordovician to lower silurian shallow marine succession of anticosti island eastern canada provides one of the most complete records across the hirnantian in the world this study reports a diverse assemblage of scolecodonts polychaete jaws from the upper katian and hirnantian vaureal ellis bay and basal becscie formations of western anticosti the collection of 10 samples includes ca 30 species representing 10 families the fauna is dominated by polychaetaspids mochtyellids paulinitids and polychaeturids the family xanioprionidae and genera pistoprion tetraprion and rakvereprion are documented for the first time from the ordovician of laurentia the anticosti polychaete fauna shows great similarity to the contemporaneous faunas of baltoscandia this is evidenced by a high relative abundance of mochtyellids and polychaeturids and a number of common species thus suggesting that the closing iapetus ocean at that time did not constitute a barrier for the dispersal of jaw bearing polych

stromatolitic framework of carbonate mud mounds abstract mud mounds are an important phanerozoic reef type generally formed in deeper water on carbonate shelf to basin slopes they commonly contain radiaxial calcite spar filled depositional cavities stromatactis but lack abundant metazoan framebuilders mud mounds are often flanked by steeply dipping bioclastic grainstones and sometimes attained widths and depositional reliefs of over a hundred meters they occasionally occur as basal cores on which developed shallow water metazoan constructed reefs stromatactoid mud mounds are composed of a framework of submarine cemented crudely reticulate masses or a succession of laminar crusts surrounded by cement filled cavities these cavities developed when unconsolidated sediment around the framework was removed by winnowing mud mound frameworks of all ages show strong geometric and petrographic similarities to shallow water cryptalgal structures especially thrombolites unlaminated stromatolites which occur in many phanerozoic shallow water reefs both thrombolites and mud mound frameworks are largely composed of lime mudstone cemented on the sea floor and contain fenestral fabric and diagnostic cryptalgal microstructure their depositional surfaces were irregular not bored or burrowed and rarely encrusted stromatolitic lamina ion although commonly not well developed in the subtidal zone anyway occasionally occurs in mud mounds it is proposed that mud mounds accumulated from organic probably blue green algal binding of locally derived lime mud and bioclasts deposited relatively slowly from suspension patchy distribution of algal mats resulted in areas of both bound and unbound sediment sporadic floodlike episodes of rapid sedimentation however temporarily smothered the living algal mat and also left layers of unbound sediment periods of winnowing washed out unconsolidated unbound sediment and promoted synsedimentary cementation of resulting stromatactoid cavities and algal bound framework

diversification and biogeography of scolecodont bearing polychaetes in the ordovician scolecodonts are common microfossils in palaeozoic rocks bearing witness to the extensive radiation of jawed polychacte worms during the ordovician period information on ordovician scolecodonts is increasing though it is still patchy and strongly skewed towards baltica and laurentia comparison of the faunas of these two palaeocontinents indicates that approximately 50 of the genera but only a few species had intercontinental distribution meagre data from other terranes also show that several genera were cosmopolitan in total more than 50 ordovician genera are known the first records are from the furongian latest cambrian but scolecodont diversity and abundance remained very low until the darriwilian the earliest jawed polychaetes had primitive usually symmetrical placognath ctenognath type jaw apparatuses xanioprionids tetraprionids and or conjungaspids seem to have played an important role in the early evolution and diversification of scolecodont beating polychactes the first more advanced taxa such as the polychaetaspids with labidognath type jaw apparatuses and mochtyellids with placognath type apparatuses and compound maxillae are first recorded in the earliest mid ordovician the most significant increase in global generic diversity but also regional species level diversity occurred in the late mid ordovician when many common taxa appeared accordingly the origination rate is highest in that interval since many ordovician polychaete genera are relatively long ranging extending into the silurian the extinction rate is low throughout the period increasing only slightly in the latest late ordovician the normalised diversity curve is characterised by an increasing trend in the mid ordovician followed by a plateau in the late ordovician c 2006 elsevier b v all rights reserved less

frictionally induced asymmetries in wind driven flows the effect of the parameterization of lateral friction on the separation of western boundary currents is addressed in an idealized context the study is motivated by a puzzling issue that arises from the nonlinear theory of the wind driven double gyre circulation in shallow water models subtle changes in the representation of the lateral friction in these models have a substantial effect on both steady state and transient flows the aim of this paper is to explain how lateral friction introduces a north south asymmetry in the steady double gyre flows and why the degree of this asymmetry depends on the type of frictional parameterization a more conceptual model of a zonal jet in a channel turns out to be very useful to determine the dynamical processes behind the asymmetries it is also shown that the north south asymmetries have an impact on the low frequency variability of the timedependent flows this is caused by changes in stability behavior of the steady state flows

el castillo cantabria northern iberia and the transitional aurignacian using radiocarbon dating to assess site taphonomy abstract the majority of archaeological remains found at el castillo in northern iberia were excavated between 1910 and 1914 by hugo obermaier since the 1980s el castillo has been studied through a detailed analysis of obermaier s original excavation notes the cleaning and study of the extant section and the excavation of material in the shelter entrance radiocarbon dating of charcoal from the modern 1980s onwards excavation suggested that unit 18 corresponding to aurignacian delta of the 1910s excavation was significantly earlier than other aurignacian assemblages in western europe combined with a reanalysis of the lithic and osseous industry these dates led to the suggestion that material in unit 18 and aurignacian delta was a transitional industry showing a gradual transformation of the mousterian into the upper palaeolithic the conclusion has profound implications for understanding the appearance of the upper palaeolithic in western europe however the theory has been heavily debated with criticism focusing on the analysis of the lithic and bone assemblage as well as the chronology we focus on the latter and assess whether the original dates were accurate whether they were well associated with the archaeology and whether there was vertical and lateral variation in the age of the assemblages within unit 18 and aurignacian delta new radiocarbon dates on humanly modified bone suggest that in the new area of excavation unit 18 is found to be earlier than 42 cal kbp with no evidence of material of a younger age in contrast in the old excavation area aurignacian delta does include material of a younger age this suggests that discussion of the transitional aurignacian can only include material from unit 18 in the new area of excavation

sensitivity of eddy induced heat transport to diabatic forcing compensation of the poleward eddy heat transport by the heat transport of an eddy induced mean meridional overturning cell is a common feature in many eddy resolving ocean models it has been argued that this is the result of the weak thermal driving of the ocean as the actual air sea coupling is scale dependent it might be questioned whether the approximation of weak thermal driving is relevant for the oceanic eddy field in this paper the role of diabatic forcing in modifying eddy mean flow interaction is investigated emphasis has been placed on the sensitivity of the eddy induced change in heat transport to the sea surface thermal boundary condition experiments have been performed with a multilayer isopycnic primitive equation model of an idealized north atlantic subtropical and subpolar gyre for different values of the air sea coupling solutions with and without transient eddies have been compared the air sea coupling mostly affects the upper ocean thermal and velocity fields a decrease of the coupling timescale pushes the separation point of the midlatitude jet further northward and induces a tight recirculation southwest of the separated jet these effects are enhanced by the eddies in the present model there is compensation of the eddy heat transport for sea surface temperature sst relaxation times longer than 150 days a breakdown of the compensation occurs for sst relaxation times shorter than 50 days the average upper layer depth is 200 m in between is a transition regime for strong thermal driving the eddy induced change in total heat transport is of the same order as the eddy heat transport

paleozoic stromatactis and zebra carbonate mud mounds global abundance and paleogeographic distribution carbonate mud mounds with zebra and stromatactis structures are present in every paleozoic system and series but are more common in devonian and carboniferous deposits reaching their acme in mississippian system lower carboniferous rocks global distributions illustrate that mud mounds spanned the planet ranging from tropical to polar circles such a wide latitudinal span signifies that they not only grew in and occupied warm depositional environments but also in settings where oceanic waters were cold and seasonally light limited moreover their proliferation during the devonian and carboniferous was at a time when planet wide climatic ice house conditions are thought to have prevailed mud mounds therefore may also be products of cool and cold water carbonate sedimentation

boundary current eddies and their role in the restratification of the labrador sea an idealized model is used to study the restratification of the labrador sea after deep convection with emphasis on the role of boundary current eddies shed near the west coast of greenland the boundary current eddies carry warm buoyant irminger current water into the labrador sea interior for a realistic end of winter state it is shown that these irminger current eddies are efficient in restratifying the convected water mass in the interior of the labrador sea in addition it is demonstrated that irminger current eddies can balance a significant portion of the atmospheric heat loss and thus play an important role for the watermass transformation in the labrador sea

pre screening techniques for identification of samples suitable for radiocarbon dating of poorly preserved bones under certain environmental conditions post depositional diagenetic loss of bone collagen can severely reduce the number of bones from a particular archaeological site that are suitable for stable isotopic analysis or radiocarbon dating this study examined nearly 300 bones from 12 archaeological sites across southern england known to yield poor or variable preservation to try to identify one or more pre screening technique s that would indicate suitable collagen preservation for radiocarbon dating the most reliable method was shown to be the percent nitrogen n of whole bone powder which has an 84 chance of successfully predicting whether or not a bone will yield sufficient i e 1 weight collagen for dating

dynamical analysis of a satellite observed anticyclonic eddy in the northern bering sea the characteristics and evolution of a satellite observed anticyclonic eddy in the northern bering sea during march and april 1999 are investigated using a three dimensional princeton ocean model pom the anticyclonic like current pattern and asymmetric feature of the eddy were clearly seen in the synthetic aperture radar sar sea surface temperature and ocean color images in april 1999 the results from model simulation reveal the three dimensional structure of the anticyclonic eddy its movement and dissipation energy analysis indicates that the barotropic instability bti is the main energy source for the growth of the anticyclonic eddy the momentum analysis further reveals that the larger magnitude of the barotropic pressure gradient in the meridional direction causes the asymmetry of the anticyclonic eddy in the zonal and meridional directions while the different magnitudes of the meridional baroclinic pressure gradient are responsible for the different intensity of currents between the northern and southern parts of the anticyclonic eddy

on the validity of downgradient eddy closures in ocean models results are presented from an eddy resolving primitive equation ocean model to test the hypothesis that geostrophic eddies can be parameterized through a variety of downgradient closures time mean eddy fluxes of temperature isopycnic thickness and quasi geostrophic potential vorticity are diagnosed on level surfaces from 5 years of model data and are spatially correlated with the corresponding time mean gradients we find no discernible correlation between the absolute eddy fluxes and mean gradients however after decomposing the eddy fluxes into rotational and divergent components we find a positive correlation between the divergent eddy fluxes and the mean gradients although the overall correlation coefficients remain small typically o 0 2 the correlation between the eddy temperature fluxes and mean temperature gradients is positive only over the upper 2 km and is negative at depth suggesting that the abyssal temperature fluxes are upgradient in contrast the correlations between eddy fluxes and mean gradients of isopycnic thickness and potential vorticity are positive over the most of the fluid column the overall correlations are similar for both thickness and potential vorticity closures we further decompose the divergent component of the eddy fluxes into components directed perpendicular and parallel to mean contours we find that both the perpendicular and the parallel components are similar in magnitude

bone diagenesis in the european holocene ii taphonomic and environmental considerations we have applied cluster analysis to mercury intrusion porosimetry data from 219 archaeological bones 121 human and 98 animal and soil chemistry data from 219 accompanying soil samples 1 per bone sample to investigate the influence of soil chemistry on bone preservation the samples chosen for the study were obtained from sites ranging in time from the pre modern to the mesolithic and were representative of burial environments across europe from the baltic to the mediterranean these results represent the single largest database for archaeological bone preservation in the european holocene to date and demonstrate the potential for large scale diagenetic studies to help develop long term preservation strategies for our european heritage despite the variety of sites and environments bones could be categorised into only four main diagenetic types furthermore soil chemistry appears to significantly affect only one type of preservation the pathway characterised by loss of mineral in neutral to basic soils taphonomy and in particular the differences between the treatment of human and animal remains becomes the dominating factor in determining preservation using these results strategies for heritage management of archaeological sites can be suggested grouping sites into those requiring immediate excavation and those where in situ preservation is viable

signature of la nina in interannual variations of the east india coastal current during spring we have investigated interannual variations of the spring february april average east india coastal current eicc magnitude between 2000 and 2018 using oscar ocean surface current analysis real time current and a linear continuously stratified lcs model interannual variability of the eicc shows significant decrease in magnitude during spring of 2000 2008 and 2011 the years when high negative oni oceanic nino index for sea surface temperature value has been observed due to dominance of strong la nina events our lcs model also successfully simulates these interannual variability of the spring average eicc between 2000 and 2018 we carried out numerical experiments using lcs model related to local and remote forcing response on eicc dynamics of the eicc during spring are dominated by four different forcing processes local wind along east coast of india remote forcing response from the eastern and northern boundary of the bob including islands interior bob and the equatorial indian ocean eio during el nino and normal spring years strong poleward interannual eicc are due to very weak negligible order of 0 5 cm s 1 eicc from eio remote response and in phase poleward eicc formation using other three forcings however during la nina spring years weak order of 0 10 cm s 1 poleward interannual eicc are formed due to destructive interference between equatorward current order of 10 25 cm s 1 from eio forcing and in phase poleward current from other three forcings we have also found propagation of interannual upwelling downwelling favorable kelvin wave from eio via eastern and western boundary of the bob during spring in the el nino la nina years the interannual variations in the propagation of eio kelvin wave are associated with the changes in the eio zonal wind direction by climate mode like enso el nino southern oscillation

a census of eddy activities in the south china sea during 1993 2007 1 numerous mesoscale eddies occur each year in the south china sea scs but their statistical characteristics are still not well documented a pacific basin wide three dimensional physical biogeochemical model has been developed and the result in the scs subdomain is used to quantify the eddy activities during the period of 1993 2007 the modeled results are compared with a merged and gridded satellite product of sea level anomaly by using the same eddy identification and tracking method on average there are about 32 9 2 4 eddies predicted by the model and 32 8 3 4 eddies observed by satellite each year and about 52 of them are cyclonic eddies the radius of these eddies ranges from about 46 5 to 223 5 km with a mean value of 87 4 km more than 70 of the eddies have a radius smaller than 100 km the mean area covered by these eddies each year is around 160 170 km2 equivalent to 9 8 of the scs area with water depths greater than 1000 m linear relationships are found between eddy lifetime and eddy magnitude and between eddy vertical extent and eddy magnitude showing that strong eddies usually last longer and penetrate deeper than weak ones interannual variations in eddy numbers and the total eddy occupied area indicate that eddy activities in the scs do not directly correspond to the el nino southern oscillation events the wind stress curls are thought to be an important but not the only mechanism of eddy genesis in the scs

the influence of negative viscosity on wind driven barotropic ocean circulation in a subtropical basin abstract in this paper a new barotropic wind driven circulation model is proposed to explain the enhanced transport of the western boundary current and the establishment of the recirculation gyre in this model the harmonic laplacian viscosity including the second order term the negative viscosity term in the prandtl mixing length theory is regarded as a tentative subgrid scale parameterization of the boundary layer near the wall first for the linear munk model with weak negative viscosity its analytical solution can be obtained with the help of a perturbation expansion method it can be shown that the negative viscosity can result in the intensification of the western boundary current second the fully nonlinear model is solved numerically in some parameter space it is found that for the finite reynolds numbers the negative viscosity can strengthen both the western boundary current and the recirculation gyre in the northwest corner of the basin the drastic increase of the mean and eddy kinetic en

eddy subduction in a model of the subtropical gyre abstract subduction is the process by which fluid transfers from the mixed layer to the interior of the ocean south of the gulf stream extension 18 mode water is formed in a region of high subduction rates in this region there is high mesoscale eddy activity in the present study the role of eddies in modifying the large scale subduction into mode water is investigated an eddy resolving isopycnic ocean model with mixed layer physics included and coupled to an atmospheric anomaly model is used for this purpose the geometry and forcing of the model are idealized annual mean subduction rates into mode water up to 200 m yr 1 are found south of the gulf stream extension the eddy contribution to the annual subduction is estimated by comparing the annual mean subduction rates obtained from monthly mean quantities with the total subduction rates i e eddy plus mean contributions the latter are determined by integrating the detrainment rates over the period when fluid is irreversibly detrained eddy

bone diagenesis and radiocarbon dating of fish bones at the shag river mouth site new zealand the shag river mouth site in southern new zealand has yielded a series of radiocarbon determinations from multiple sample types which suggest that the site was occupied briefly in the 14th century ad radiocarbon determinations of bone disclose a greater variation which has been attributed to problems of sample degradation contamination inadequate pretreatment or the use of sub fossil bones in prehistory we examined the dating of bone at the site using barracouta thyrsites atun fish bone in order to determine whether this material could be dated accurately we applied a series of analytical tests to ascertain the preservation state and the extent of post depositional contamination these data were used to predict which samples would be most useful for14c analysis the resultant ages with the exception of two problematic samples are consistent with those on other acceptable marine and estuarine shell carbonate samples based on the available results we suggest that barracouta fish bone from this site is well preserved and reliable for dating we re examined previous determinations of moa and rat bone from different parts of the site to evaluate their accuracy in the light of this new data

origin and dynamics of mesoscale eddies in the catalan sea nw mediterranean insight from a numerical model study past observations and satellite sea surface temperature imagery indicate the presence of mesoscale anticyclonic eddies drifting along the catalan coast in september 2001 one of these anticyclonic eddies was surveyed over the shelf break during an oceanographic cruise which permitted the 3 d description of its structure in this work we investigate the origin and dynamics of such catalan eddies using a numerical circulation model of the northwest mediterranean at 3 km resolution driven by high resolution atmospheric analyses and compare model eddies with the observations in the catalan sea we identify two zones of eddy formation in the gulf of lions in front of the city of marseille and at the southeast of coast of roussillon from which anticyclonic eddies are observed to drift toward the catalan sea the hydrology and dynamics of the structures observed in the simulations are characterized sensitivity experiments and energy analysis are performed which allow us to identify the mechanisms associated with their generation properties of the eddy observed during the 2001 cruise at the catalan shelf break are found to compare well with model eddies generated at the southeast of the roussillon coast the model relates the origin of these eddies to the separation of the coastal current downstream from creus cape flow separation is linked to intense downwelling taking place in front of the roussillon coast when strong northwesterly winds events occur

petrous bone diagenesis a multi analytical approach abstract the discovery of petrous bone as an excellent repository for ancient biomolecules has been a turning point in biomolecular archaeology especially in adna research but excessive and uncontrolled sampling could result in loss of this valuable resource for future research this study reports on the histological optical microscopy physical ftir atr elemental chn and biochemical collagen and dna analysis preservation of 15 human petrous bones spanning from the c 2100 bce to 1850 ce through the combined application of a number of diagenetic parameters general histological index infrared splitting factor carbonate phosphate ratio amide phosphate ratio col wt c n and c n of whole bone and collagen endogenous dna we provide new insights into petrous bone micromorphological characteristics and diagenesis and new evidence to enhance screening practices for adna and collagen analysis

differential burning recrystallization and fragmentation of archaeological bone abstract this paper presents research on the conditions under which progressive levels of burning may occur to archaeological bone and how burning damage changes bones crystal structure and susceptibility to fragmentation a k a friability experiments were conducted to simulate common patterns of high temperature bone diagenesis and fragmentation previously documented in paleolithic shelter sites bones buried up to 6 cm below the coal beds of the experimental fires were carbonized but calcination occurred only with direct exposure to live coals analysis by infra red spectroscopy reveals that marked changes in crystallinity accompany the macroscopic transformations in colour and friability of modern fire altered bone specifically a monotonic non linear decrease in mean fragment length across six colour categories was observed when samples were agitated or trampled and a concordant decline in bone identifiability first with respect to skeletal element and ultimately the recognizability of bone tissue itself these findings help qualify the behavioural and taphonomic implications of fragmented burned bones in archaeological sites especially with regard to potential stratigraphic associations between artefacts and hearth features in sites and the intensity of space use by human occupants the identification of burning damage on archaeological bone is a separate issue however it was found that the molecular signatures of recrystallization in modern burned bones partly overlap with recrystallization caused by weathering after only 1 to 2 years of exposure in an arid setting and by partial fossilization of archaeological bones over the long term while infra red and x ray diffraction techniques effectively describe heat induced changes in modern bone mineral and are an important aid for modelling diagenetic processes these techniques did not reliably identify burning damage to archaeological bones cross referencing readily visible colour phases with hcl insoluble fraction data proves much more effective and economically feasible for the latter purpose

sources of eddy kinetic energy in the labrador sea experiments with a suite of north atlantic general circulation models are used to examine the sources of eddy kinetic energy eke in the labrador sea a high resolution model version 112 quantitatively reproduces the observed signature a particular feature of the eke in the labrador sea is its pronounced seasonal cycle with a maximum intensity in early winter as already found in earlier studies based on altimeter data in contrast to a previously advanced hypothesis the seasonally varying eddy field is not related to a forcing by high frequency wind variations but can be explained by a seasonally modulated instability of the west greenland current wgc the main source of eke in the labrador sea is an energy transfer due to reynolds interaction work barotropic instability in a confined region near cape desolation where the wgc adjusts to a change in the topographic slope geostrophic contours tend to converge upstream of cape desolation such that the topographically guided wgc narrows as well and becomes barotropically unstable the eddies spawned from the wgc instability area dominating the eke in the interior labrador sea are predominantly anticyclonic with warm and saline cores in the upper kilometer of the water column while the few cyclones originating as well from the instability area show a more depth independent structure companion experiments with a model exhibit the strength of the wgc influenced by either changes in the wind stress or heat flux forcing as a leading factor determining seasonal to interannual changes of eke in the labrador sea

the nature of eddy kinetic energy in the labrador sea different types of mesoscale eddies their temporal variability and impact on deep convection abstractoceanic eddies are an important component in preconditioning the central labrador sea ls for deep convection and in restratifying the convected water this study investigates the differen

the eddy field associated with the azores front east of the mid atlantic ridge as observed by the geosat altimeter two years of geosat data november 1986 to december 1988 for the azores madeira region of the north atlantic are analyzed the objective is to study the eddy field associated with the terminal retroflection of the azores current the rms variability of sea level anomaly is 4 to 8 cm with maximum values between 33 degrees and 35 degrees n being associated with the azores current and located on its northern flank higher energy is observed during winter and during the year november 1987 to november 1988 analysis of velocities at crossovers reveals anisotropy with larger meridional velocity variances this is the signature of meanders and or eddies elongated in the north south direction the eddy mean flow interaction is studied through the analysis of the reynolds tensor meridional and zonal accelerations of the mean by the eddy field are consistent with retroflection of the azores current to the south and to the west spectral analyses show that the dominant signals have periods and wavelengths larger than 100 days and 300 km respectively propagation velocities are westward but slow 1 5 km d synoptic mapping of the eddy field shows the wavelike structure of the variability on the northern flank of the current it is likely that the wave generation is not directly due to an instability of the azores current but is attributable to a cause more to the east once formed the wave interacts with the current in winter and forms meanders seasonal variations of the surface circulation are finally analyzed from the 2 year long time series of synoptic maps there is a clear seasonality in the surface circulation which generally appears to be consistent with historical in situ measurements in winter there is a strong meandering and a southward branching while in summer the mean front is narrower and penetrates further to the east

eddy dynamics in a primitive equation model sensitivity to horizontal resolution and friction a primitive equation model of an idealized ocean basin driven by simple study wind and buoyancy forcing at the surface is used to study the dynamics of mesoscale eddies model statistics of a six year integration using a fine grid 1 6 0 2 with reduced coefficients of horizontal friction are compared to those using a coarser grid 1 3 0 4 but otherwise identical configuration eddy generation in both model cases is primarily due to the release of mean potential energy by baroclinic instability horizontal reynolds stresses become significant near the midlatitude jet of the fine grid case with a tendency for preferred energy transfers from the eddies to the mean flow using the finer resolution eddy kinetic energy nearly doubles at the surface of the subtropical gyre and increases by factors of 3 4 over the jet region and in higher latitudes the spatial characteristics of the mesoscale fluctuations are examined by calculating zonal wavenumber spectra and velocity autocorrelation functions with the higher resolution the dominant eddy scale remains approximately the same in the subtropical gyre but decreases by a factor of 2 in the subpolar areas the wavenumber spectra indicate a strong influence of the model friction in the coarse grid case especially in higher latitudes using the coarse grid there is almost no separation between the energetic eddy scale and the scale where friction begins to dominate leading to steep spectra beyond the cutoff wavenumber using the finer resolution an inertial subrange with a k 3 power law begins to emerge in all model regions outside the equatorial belt despite the large increase of eddy intensity in the fine grid model effects on the mean northward transport of heat are negligible strong eddy fluxes of heat across the midlatitude jet are almost exactly compensated by changes of the heat transport due to the mean flow

patterns of diagenesis in bone i the effects of site environments abstract we have measured a suite of diagenetic parameters for several populations of archaeological bones buried in a number of northwest european sites since the last ice age these are the structural damage due to microbes changes in bone micro and macro porosity protein content a measure of the crystallinity of hydroxyapatite as reflected in the phosphate infra red spectrum peak splitting and a measure of the carbonate content as given by the ratio of carbonate to phosphate infra red absorption peaks the results provide a database that clearly characterises the patterns which are often site dependent of diagenetic change in buried bone our main conclusions are that individual site hydrology appears to have a strong influence on the outcome of bone preservation and that porosity is the most effective single diagenetic parameter which both determines and reflects the preservation of bone in the burial environment

ordovician reef and mound evolution the baltoscandian picture the widespread growth of reefs formed by a framework of biogenic constructors and frame lacking carbonate mounds began on baltica during ordovician time previously ordovician reef and mound development on baltica was considered to be sporadic and local a review of all known bioherm localities across the baltic basin reveals a more consistent pattern ordovician bioherms grew in a wide e w aligned belt across the baltic basin and occur in several places in norway substantial reef development began simultaneously across the region during the late sandbian early katian interval and climaxed during the late katian pirgu age the current spatiotemporal distribution of bioherms is a result of interdependent factors that involve original drivers of reef development such as relative sea level climate during the time of deposition and effects of post depositional erosion oceanographic conditions were likely more favourable during times of cooler global climates low sea level and glacial episodes at the same time the likelihood that bioherms are preserved from long term erosion is higher when deposited during low sea level in deeper parts of the basin a main factor controlling the timing of the reef and mound evolution was baltica s shift toward palaeotropical latitudes during late ordovician time the time equivalence between initial reef growth and the guttenberg isotope carbon excursion gice suggests that global climatic conditions were important

large structures and temporal change in the azores front during the semaphore experiment the structure des echanges mer atmosphere proprietes des heterogeneites oceaniques recherche experimentale semaphore mesoscale experiment took place from july to november 1993 in the northern canary basin where the circulation is dominated by the eastward flowing azores current ac a large data set was acquired from three hydrographic arrays phases 1 2 3 current meter moorings surface drifters drogued at 150 m and 2000 m deep rafos floats the analysis confirmed the large scale observations previously made in this region but also provided new insights into fine scale dynamics of the ac the front was observed over the 6 month period it was narrow 100 km and mostly surface intensified velocities reaching 40 50 cm s 1 whereas at the beginning of the experiment phase 1 the ac was mainly zonal with weak oscillations large meridional meanders were observed from phase 2 until the end of the experiment they seem to be related to the arrival of two mediterranean eddies meddies which interacted with the ac kase and zenk 1996 tychensky and carton this issue the front had a deep dynamical signature down to 2000 m with a 16 18 sverdrup sv volume transport 0 2000 m depth integrated the southward recirculation branch of the ac near 22 degrees 23 degrees w klein and siedler 1989 corresponds to meridional transport of 5 6 sv then 4 5 sv of these waters are recirculating westward along 31 degrees 32 degrees n some interesting new oceanographic results were obtained by examining the rafos float trajectories over the abyssal plain the circulation is similar to that observed at the surface with mean velocities of about 1 3 cm s 1 and eddy kinetic energy 4 cm 2 s 2 in agreement with the analysis of current meter data this reveals a significant barotropic component in the azores madeira flow field of roughly 3 3 5 cm s 1

polychaete palaeoecology in an early late ordovician marine astrobleme of sweden the post impact dalby limestone kulcruse upper ordovician of the tvaren crater southeastern sweden has been analysed with regards to polychaetes as represented by scolecodonts a palaeoecological succession is observed in the tvaren 2 drill core sequence as the vacant ecospace was successively filled by a range of benthonic nektonic and planktonic organisms scolecodonts belong to the first non planktonic groups to appear and constitute one of the most abundant fossil elements the polychacte assemblage recorded has an overall composition characteristic of that of the upper ordovician of baltoscandia oenonites vistulella mochtyella and the enigmatic xanioprion represent the most common genera whereas pteropelta protarabellites atraktoprion and xanioprion are considerably more rare the assemblage differs from coeval ones particularly in its poorly represented ramphoprionid fauna and the relatively high frequency of xanioprion a taxonomic succession and changes in abundance and relative frequency of different taxa is observed from the deepest part of the crater and upwards towards more shallow water environments the initial post impact assemblage does not however necessarily represent a benthonic colonization of the crater floor instead it seems to be a taphocoenosis as indicated by its taxonomic correspondence to the rim facies fauna recovered from dalby limestone erratics of the ringson island the tvaren succession has yielded considerably richer scolecodont assemblages than hitherto recorded from the approximately coeval lockne crater possibly as a consequence of shallower water settings in the former area

preparation and characterization of bone and tooth collagen for isotopic analysis abstract criteria are presented for the identification of diagenetic alteration of carbon and nitrogen isotope ratios of bone and tooth collagen prepared by a widely used method measurements of collagen concentrations in tooth and bone atomic c n ratios and carbon and nitrogen concentrations in collagen of 359 historic and prehistoric african humans and modern and prehistoric east african non human mammals are described carbon isotope ratios of collagen lipids from four bones are also presented compared to bone whole teeth have significantly lower collagen concentrations lower carbon and nitrogen concentrations in collagen and similar c n ratios carbon and nitrogen concentrations and c n ratios are relatively constant over a wide range of collagen concentrations however prehistoric specimens with very low collagen concentrations have highly variable c n ratios very low carbon and nitrogen concentrations in collagen and stable carbon and nitrogen isotope ratios unlike collagen at the transition from well preserved to poorly preserved collagen the most reliable indicator of collagen preservation is the concentration of carbon and nitrogen in collagen concentrations of c and n drop abruptly by an order of magnitude at this transition point these attributes provide simple criteria for assessing sample quality since collagen preservation can vary greatly within prehistoric sites these attributes should be reported for each specimen use of purification procedures that remove acid and base soluble contaminants and particulate matter carbonates fulvic acids lipids humic acids sediments and rootlets are recommended wider adoption of these procedures would insure comparability of results between laboratories and permit independent and objective evaluation of sample preservation and more precise dietary climatic and habitat interpretations of collagen isotopic analyses

an investigation into the internal and external variables acting on crystallinity index using fourier transform infrared spectroscopy on unaltered and burned bone abstract the crystallinity index is a measure of structural order in bone and is potentially an extremely useful tool in bioarchaeology since it can assist in sequencing bones into chronological and or stratigraphic order act as an indicator for preservation and assist in reconstructing burning events unfortunately concerns over influencing variables and bone sampling issues inhibit full and wide spread adoption of this approach an attempt has been made to determine the influence of a number of internal and external variables on bone crystallinity changes ci c p and c c were calculated using fourier transform infrared spectroscopy attenuated total reflectance ftir atr on modern burned and unburned faunal bone samples were taken systematically across bone elements and on the internal and external surfaces the ci results support previous work and show increases with burning intensity it is also shown that extrinsic variables such as temperature and duration of burning have more of a significant influence on ci values than intrinsic variables such as location of sample site on the bone a sampling strategy is suggested for those wishing to use the ci on bone in archaeological contexts

chrono stratigraphy of the upper pleistocene and holocene archaeological sequence in cova gran south eastern pre pyrenees iberian peninsula the cova gran de santa linya lleida spain is a recently discovered site with a broad chrono cultural sequence that contains archaeological levels dating to the middle palaeolithic early upper palaeolithic late upper palaeolithic neolithic and early bronze age we present the chronometric and stratigraphic context of these occupations which were dated using 14c accelerator mass spectrometry and thermoluminescence the sequence provides important indicators that aid in the reconstruction of the history of human occupation on the southern slopes of the spanish pyrenees over the past 50 000 years copyright 2011 john wiley sons ltd

bone diagenesis in the european holocene i patterns and mechanisms diagenetic changes in archaeological bone are known to influence the data derived from such material and have thus been the subject of numerous studies a number of general trends have been observed but many of the processes that occur are still not fully understood we present here the analysis of 195 bones excavated from 32 sites in five different countries from eurasia characterized using 10 simple diagenetic parameters the results reveal that most european holocene archaeological bone can be categorized by only four main diagenetic states related to three distinct trajectories that describe more than 60 of the variation in these parameters given the potential amount of variation in the dataset the small number of diagenetic pathways is surprising but highlights the large importance of a few key factors that influence bone diagenesis mercury intrusion porosimetry is a key technique for identifying modes of degradation

diagenesis of bones from eland s bay cave abstract archaeological bone specimens have been shown in a number of studies to have increased mineral crystallinity when measured both by xrd and ir spectrometry in this study we investigated the relative dating potential of ir crystallinity measurements based on the splitting factor or sf on a sample of 54 specimens from the holocene sequence at eland s bay cave south africa in addition to sf c and n measurements were obtained using a carlo erba elemental analyser results of the study indicate that i a reasonably good correlation between sf and time exists in bones under 20 000 years bp but that the increase in sf levels off after this period and ii correlations between diagenetic indicators such as sf c and n are better than those between any indicator and time an excellent correlation r2 0 81 was obtained between sf residing in the inorganic phase and n residing in the organic phase suggesting that diagenesis of the two phases of bone are linked implications of the data for monitoring stratigraphic anomalies at archaeological sites are discussed

can eddies set ocean stratification abstract a simple theory is presented for the buoyancy anomaly and depth of penetration of a warm lens created by a surface buoyancy flux and ekman pumping in an initially homogeneous rotating fluid it is assumed that the overturning of isopycnals induced by pumping and differential heating balances the counteroverturning tendency of baroclinic instability baroclinic eddies not only develop on the stratified lens but also play a fundamental role in setting its stratification the theory is successfully tested against numerical and laboratory experiments in which the mechanically induced deepening of a buoyant lens is arrested by its baroclinic instability finally the possibility is discussed that the eddy transfer process studied here might play a role in setting the stratification and depth of the main thermocline in the ocean

vagrant benthos annelida polychaeta associated with upper ordovician carbonate mud mounds of subsurface gotland sweden micropalaeontological investigations of upper ordovician carbonate mud mounds and enclosing strata of subsurface gotland sweden demonstrate that jaw bearing polychaetes formed the most diverse faunal element associated with these build ups although not present within the mound cores intra mound facies scolecodonts or polychaete jaws occur abundantly immediately below and particularly above the mounds the supra mound facies also has the most diverse fossil assemblages by contrast to the scolecodont distribution the most diverse conodont faunas were recorded in the intra mound facies this reinforces the fact that scolecodont and conodont abundance and diversity numbers are commonly inverse to one another suggesting that these metazoans occupied different niches and responded differently to taphonomical processes the polychaete assemblage has no less than 27 species belonging to 12 genera of which oenonites mochtyella and pistoprion are the most abundant the assemblage has a characteristic baltic signature and is similar in taxonomic composition to coeval ones from other areas of the baltoscandian palaeobasin such as that of present day estonia a principal component analysis clusters the gotland assemblage most closely to those recorded from shallow to transitional shelf environments of estonia indicatino that the mud mounds were formed in such environments less

the radiocarbon dating of bone abstract diagenetic changes in bone are liable to cause erroneous radiocarbon dates on bone because of the mixing of sample and environment c atoms they can bring about likewise radiocarbon dating can provide information on the extent of such mixing the processes involved which may mix chemically physically or biologically the c atoms of the sample are outlined and the methods used in practice to reverse this mixing are described the most suitable methods depend on the state of preservation of the bone the type of environment and the radiocarbon content bones are classified according to different categories and the appropriate methods indicated for each category it is clear that the more difficult cases are at present not reliably dated and must await a better understanding of the chemistry of diagenesis

near surface mean circulation and kinetic energy in the central north atlantic from drifter data an analysis of a large drifting buoy data set is presented the objective is to obtain a self contained description of the properties of the near surface circulation drogue depth 100 m in the central north atlantic ocean independent of hydrographic data a necessary preanalysis step was the removal of all data from undrogued buoys from the data set the physical parameters of the circulation were deduced by averaging the remaining data in 2 3 boxes the minimum amount of data which is necessary to get statistically stable results was determined by an empirical quality criterion all important mean currents in the investigation area are reproduced by the near surface mean velocity field a separation of the mean velocity field into a nondivergent and an irrational part shows that the flow field is almost nondivergent the distribution of eddy kinetic energy is concentrated along the mean currents and provides the largest part of the total kinetic energy but there are regional variations energy from inertial movements dominates the high frequency part of the kinetic energy its distribution is very patchy the analysis of the reynolds stress terms shows an energy transfer from the eddy field to the mean circulation in the vicinity of the north atlantic current

mesoscale activity in the comoros basin from satellite altimetry and a high resolution ocean circulation model recently it has been shown that anticyclonic eddies are generated in the comoros basin contesting the long held notion of a single large anticyclonic cell the comoros gyre limited knowledge exists about the mesoscale activity within the basin a potential key source of variability for the mozambique channel and subsequently the agulhas current in this paper an automated eddy tracking scheme applied to satellite altimetry data and a high resolution model simulation is used to determine the characteristics of the anticyclonic eddies generated in the comoros basin the generation and characteristics of cyclonic eddies are also investigated the eddy tracking scheme revealed that anticyclonic eddies are primarily generated west of the tip of madagascar due to barotropic instabilities whereas cyclonic eddies are mainly generated along the northwest coast of madagascar as a result of baroclinic instabilities anticyclonic eddies with a mean lifespan of about 3 months reside in the basin for half their lifespan before propagating into the mozambique channel on the other hand the majority of cyclonic eddies with a similar mean lifespan dissipate within the basin initially the anticyclones with translation speeds of 6 8 km d 1 and mean radii of 80 100 km follow the trajectory of the north east madagascar current and turn south upon reaching the african coast the cyclonic eddies tend to be smaller 60 km and have slower translation speeds 2 5 3 5 km d 1 than their anticyclonic counterparts

bones and groundwater towards the modelling of diagenetic processes this paper develops a theory for describing those diagenetic changes in bone which involve its interaction with groundwater three main processes are considered as examples of such changes namely the uptake of uranium the dissolution of bone and the increase of crystallinity of the bone mineral carbonate hydroxyapatite or dahllite here simple models of the chemistry involved are postulated although how bone interacts with water on amolecularscale is not clearly known in order to demonstrate the theory with explicit mechanisms and values greater emphasis is given to uranium uptake since the model used is comparatively detailed being based on the authors previous work the basic assumption is that the rate limiting process in diagenetic change is the movement of solutes to from or within the bone therefore the main thrust of the paper is to show how the physical structure of the bone itself together with the hydrology of the burial site interact to determine how water and its solutes move into within and from a bone during burial this interaction can be of three kinds defined by the site hydrology these are termed here diffusion hydraulic flow and recharge all three types may operate together and their relative importance depends on the extent to which the pore structure of a bone has been altered by diagenesis as well as the type of chemical change taking place it is shown that diffusion is usually the most common and important process but that it is possible to predict the hydrological regimes in which other mechanisms dominate it is shown how knowledge of site hydrology mainly the specification of soil structure and moisture variation the physical state of the bone and the chemistry of the diagenetic process can provide estimates for the rate and manner of the particular diagenetic process such estimates agree with observation suggesting this approach to be on the right lines qualitative predictions also result from the theory the main value of this approach is to identify those situations where particular diagenetic changes are simplest e g sites where the hydrology gives rise to a single and quantifiable hydraulic process so that they may be decisively tested against the quantitative predictions of the theory

estimating a mean ocean state from hydrography and sea surface height data with a nonlinear inverse section model twin experiments with a synthetic dataset the recovery of the oceanic flow field from in situ data is one of the oldest problems of modern oceanography in this study a stationary nonlinear inverse model is used to estimate a mean geostrophic flow field from hydrographic data along a hydrographic section the model is augmented to improve these estimates with measurements of the absolute sea surface height by satellite altimetry measurements of the absolute sea surface height include estimates of an equipotential surface the geoid compared to oceanographic measurements the geoid is known only to low accuracy and spatial resolution which restricts the use of sea surface height data to applications of large scale phenomena of the circulation dedicated satellite missions that are designed for high precision high resolution geoid models are planned and or in preparation this study which relies on twin experiments assesses the important contribution of improved geoid models to estimating the mean flow field along a hydrographic section when the sea surface height data are weighted according to the error estimates of the future highly accurate geoid models grace gravity recovery and climate experiment and goce gravity field and steady state ocean circulation explorer integrated fluxes of mass and temperature can be determined with an accuracy that is improved over the case with no sea surface height data by up to 55 with the error estimates of the currently best geoid model egm96 the reduction of the estimated flux errors does not exceed 18

intraseasonal variability of sea surface height in the bay of bengal intraseasonal variability isv of sea surface height ssh over the bay of bengal bob is studied using altimetry data and an eddy resolving ocean model in both the model hindcast and satellite observations large ssh isv is found along the eastern and northern coasts of the bob in the western bob and in a zonal band across the bay centered near 5 degrees n the isv displays a clear seasonality in the western bob it reaches its annual maximum in spring whereas it does so in summer and autumn southeast of sri lanka driven by equatorial intraseasonal winds equatorial kelvin waves propagate eastward reach the western coast of sumatra and reflect there to propagate around the perimeter of the bob as coastally trapped waves two distinct bands of high eddy activity are detected in the western and central bob respectively in both bands isolated eddies propagate southwestward eddy formation in the eddy train in the central bay is linked to the coastal wave as it bends around the corner of the irrawaddy delta off myanmar eddy activity contributes to the high isv in the central bay to some extent an energetics analysis indicates that high total eddy energy in the western bob is due to barotropic baroclinic instability of the mean current citation cheng x s p xie j p mccreary y qi and y du 2013 intraseasonal variability of sea surface height in the bay of bengal j geophys res oceans 118 816 830 doi 10 1002 jgrc 20075

measurements and relationships of diagenetic alteration of bone from three archaeological sites four diagenetic parameters have been chosen to represent the state of diagenesis of bone buried on archaeological sites they are histological preservation protein content crystallinity and porosity how these parameters are measured is described and results from populations of bones from three different sites are presented the results show the extent and variation in the degree of change both within a site and between sites in particular the correlations between diagenetic parameters are examined which give clues about the processes which cause alteration the value of porosity determinations both at the intercrystalline level and at coarser levels in revealing the degree of diagenetic change in bone and in underlying the dynamics of the interaction between buried bone and the surrounding water is stressed the data also indicate but are too restricted to prove the following microbiological attack is generally complete within less than 500 years substantial levels of protein may remain in bone after maximal micromorphological alteration loss of protein appears to be independent of other diagenetic change the correlated lose of microporosity with increase of crystallinity suggests these changes may arise from the dissolution perhaps with subsequent recrystallization of the smallest hydroxyapatite crystallites

wind forced variability in eddy formation eddy shedding and the separation of the east australian current the east australian current eac like many other subtropical western boundary currents is believed to be penetrating further poleward in recent decades previous observational and model studies have used steady state dynamics to relate changes in the westerly winds to changes in the separation behavior of the eac as yet little work has been undertaken on the impact of forcing variability on the eac and tasman sea circulation here using an eddy permitting regional ocean model we present a suite of simulations forced by the same time mean fields but with different atmospheric and remote ocean variability these eddy permitting results demonstrate the nonlinear response of the eac to variable nonstationary inhomogeneous forcing these simulations show an eac with high intrinsic variability and stochastic eddy shedding we show that wind stress variability on time scales shorter than 56 days leads to increases in eddy shedding rates and southward eddy propagation producing an increased transport and southward reach of the mean eac extension we adopt an energetics framework that shows the eac extension changes to be coincident with an increase in offshore upstream eddy variance via increased barotropic instability and increase in subsurface mean kinetic energy along the length of the eac the response of eac separation to regional variable wind stress has important implications for both past and future climate change studies

viscosity dependent internal variability in a model of the north pacific abstract a 2 resolution isopycnal model of the north pacific ocean is shown to produce anomalies that propagate around the subtropical gyre on the decadal time scale that do not appear in a 1 resolution version of the same model a principal oscillation pattern pop analysis of the isopycnal interface anomaly is performed to examine the dynamics responsible for the anomaly generation the pops show a coherent oscillation around the entire subtropical gyre with two centers of action one in the central mode water cmw region the other in the subtropical countercurrent stcc lead lag covariances between the subduction rate in the cmw and the layer thickness along the oscillation path indicate that anomalous subduction events are not the driving mechanism for the oscillation a linearized quasigeostrophic mode analysis shows that the anomalies are generated by flow instability in the region of the stcc the instability disappears in the 1 model because of changes in the horizontal viscosity which is

why do crystallinity values fail to predict the extent of diagenetic alteration of bone mineral spectroscopic indicators of bone crystallinity such as the infrared splitting factor irsf are commonly used to determine the general state of preservation of ancient bone in principle such indices might be expected to act as a proxy for alteration of bone mineral and thus could be used to screen bones or portions of bones for likely preservation of in vivo biogenic trace element and stable isotope signals we tested the relationship between irsf and bone mineral composition in two suites of well characterised recent and pleistocene bones initially crystallinity change and trace element uptake are correlated apparently both controlled by decomposition of the organic phase and exposure of bone crystal surfaces this relationship breaks down in older bones where authigenic phosphate growth and mineral pore water interactions are no longer rate limited by the breakdown of collagen and exposure of crystal surfaces in these conditions the extent of chemical alteration of bone will be controlled by site specific conditions and thus while ftir spectra of bone provide a broad indication of organic content and apatite recrystallisation they are not reliable proxies for the degree of diagenetic alteration in terms of biogenic geochemical signals

upper ordovician sequences of western estonia abstract the upper ordovician uppermost caradoc ashgill section of western estonia consists of a series of seven open shelf carbonate sequences depositional facies grade laterally through a series of shelf to basin facies belts grain supported facies shallow shelf mixed facies middle shelf mud supported facies deep shelf and slope and black shale facies basin locally a stromatactis mud mound occurs in a middle to deep shelf position shallow to deep shelf facies occur widely across the estonian shelf and grade laterally through a transitional slope belt into the basinal deposits of the livonian basin each sequence consists of a shallowing upward prograding facies succession sequences 1 upper nabala stage and 2 vormsi stage record step wise drowning of underlying shelf units lower nabala that culminated in the deposition of the most basinal facies fjacka shale in the livonian basin sequences 3 6 comprise the overlying pirgu stage and record the gradual expansion of shallow and middle shelf facies across the estonian shelf the porkuni stage sequence 7 is bracketed by erosional surfaces and contains the shallowest water facies of the preserved strata the uppermost part of the section normalograptus persculptus biozone is restricted to the livonian basin and includes redeposited carbonate and siliciclastic grains it is the lowstand systems tract of the lowest silurian sequence 8 sequence 7 and the overlying basinal redeposited material i e the lowstand of sequence 8 correspond to the latest ordovician hirnantian glacial interval and the bracketing unconformities are interpreted as the widely recognized early and late hirnantian glacial maximums the sequences appear correlative to upper ordovician sequences in laurentia graptolite biozones indicated that the estonian sequences are equivalent to carbonate ramp sequences in the western united states great basin and mixed carbonate siliciclastic sequences in the eastern united states appalachian basin cincinnati arch region these correlations indicate a strong eustatic control over sequence development despite the contrasting tectonic settings of these basins

ssh wavenumber spectra in the north pacific from a high resolution realistic simulation abstractfollowing recent studies based on altimetric data this paper analyses the spectral characteristics of the sea surface height ssh using a new realistic simulation of the north pacific ocean with high resolution in the horizontal and 100 vertical levels this simulation resolves smaller scales down to 10 km than altimetric data limited to 70 km because of the noise level in high eddy kinetic energy eke regions as in the western part ssh spectral slope almost follows a k 4 with k the wavenumber or slightly steeper law in agreement with altimeter studies the new result is that unlike altimeter studies such a k 4 slope is also observed in low eke regions as in the eastern part in these regions this slope mostly concerns scales not well resolved by altimetric data such k 4 ssh spectral slopes are weaker from what is expected from quasigeostrophic turbulence theory but closer to surface quasigeostrophic sqg turbulence theory the consequence is that the small scales concerned

origins of eddy kinetic energy in the bay of bengal by analyzing satellite observational data and ocean general circulation model experiments this study investigates the key processes that determine the spatial distribution and seasonality of intraseasonal eddy kinetic energy eke within the bay of bengal bob it is revealed that a complicated mechanism involving both local and remote wind forcing and ocean internal instability is responsible for the generation and modulation of eke in this region high level eke mainly resides in four regions east of sri lanka region 1 the western bob region 2 northwest of sumatra region 3 and the coastal rim of the bob region 4 the high eke levels in regions 1 and 2 are predominantly produced by ocean internal instability which contributes 90 and 79 respectively prominent seasonality is also observed in these two regions with higher eke levels in boreal spring and fall due to enhanced instability of the east indian coast current and the southwest monsoon current respectively in contrast ocean internal instability contributes 49 and 52 of the total eke in regions 3 and 4 respectively whereas the atmospheric forcing of intraseasonal oscillations isos also plays an important role isos produce eke mainly through wind stress involving both the remote effect of equatorial winds and the local effect of monsoonal winds equatorial origin wave signals significantly enhance the eke levels in regions 3 and 4 in the form of reflected rossby waves and coastal kelvin waves respectively the local wind forcing effect through ekman pumping also has a significant contribution in regions 3 and 4 24 and 22 respectively

numerical simulation of the observed near surface east india coastal current on the continental slope we simulate the east india coastal current eicc using two numerical models resolution 0 1 circ times 0 1 circ an oceanic general circulation model ogcm called modular ocean model and a simpler linear continuously stratified lcs model and compare the simulated current with observations from moorings equipped with acoustic doppler current profilers deployed on the continental slope in the western bay of bengal bob we also carry out numerical experiments to analyse the processes both models simulate well the annual cycle of the eicc but the performance degrades for the intra annual and intraseasonal components in a model resolution experiment both models run at a coarser resolution of 0 25 circ times 0 25 circ simulate well the currents in the equatorial indian ocean eio but the performance of the high resolution lcs model as well as the coarse resolution ogcm which is good in the eicc regime degrades in the eastern and northern bob an experiment on forcing mechanisms shows that the annual eicc is largely forced by the local alongshore winds in the western bob and remote forcing due to ekman pumping over the bob but forcing from the eio has a strong impact on the intra annual eicc at intraseasonal periods local equatorial forcing dominates in the south north because the kelvin wave propagates equatorward in the western bob a stratification experiment with the lcs model shows that changing the background stratification from eio to bob leads to a stronger surface eicc owing to strong coupling of higher order vertical modes with wind forcing for the bob profiles these high order modes which lead to energy propagating down into the ocean in the form of beams are important only for the current and do not contribute significantly to the sea level

on the mechanisms of episodic salinity outflow events in the strait of hormuz abstract observations in the strait of hormuz 26 26 n 56 08 e during 1997 98 showed substantial velocity fluctuations accompanied by episodic changes in the salinity outflow events with amplitude varying between 1 and 2 psu on time scales of several days to a few weeks these events are characterized by a rapid increase in salinity followed by an abrupt decline the mechanisms behind these strong pulses of salinity events are investigated with a high resolution 1 km hybrid coordinate ocean model hycom with particular reference to the year 2005 in accordance with the observations the simulated salinity events are characterized by strong coherence between the enhanced flows in zonal and meridional directions it is inferred that most of the simulated and observed outflow variability is associated with the continuous formation of strong mesoscale cyclonic eddies whose origin can be traced upstream to around 26 n 55 5 e these cyclonic eddies have a diameter of about 63 km and have a remnant of p

eddy processes in semienclosed seas a case study for the black sea abstract the enclosed boundaries and small scales of some seas lead to the formation of specific physical balances which motivates the oceanographic interest in studying the dynamics of semienclosed ocean basins the focus in the paper is on the specific appearances of eddy processes when the basin scales and the ones of the topographic features are comparable with the baroclinic radius of deformation the black sea is used as a test basin eddy variability is analyzed using simulation results and compared with existing observations the bryan cox model with horizontal resolution 1 10 and 1 6 is forced with annual mean wind stress data buoyancy flux at the sea surface is proportional to the deviation of the model density from the annual mean climatological data sensitivity studies on different forcing and on the topographic control are carried out synoptic periods are estimated to be about 0 5 yr eddies form in the eastern black sea and propagate westward with a speed of about 3 cm s 1 t

states of preservation of bones from prehistoric sites in the near east a survey abstract a survey of the states of preservation of organic material in 30 fossil bones from 16 different prehistoric sites in the near east shows that whereas almost all the bones have little or no collagen preserved they do with few exceptions contain non collagenous proteins these macromolecules therefore represent an important reservoir of indigenous fossil bone constituents

radiocarbon dating of peptides isolated from contaminated fossil bone collagen by collagenase digestion and reversed phase chromatography abstract the peptide mixture resulting from collagenase enzymatic cleavage of fossil bone collagen is separated into a fraction containing the very bone specific tripeptides glycine proline hydroxyproline glyprohyp and glycine proline alanine glyproala and more hydrophobic fractions using reversedphase chromatography the suitability of these fractions for 14 c bone dating and stable isotope analysis is discussed firstly by assessing the theoretical benefits of their use as compared to other bone specific extracts and secondly by examining 14 c ages of the fractions in a selection of bones that had previously been giving dubious results using the oxford routine bone pretreatment in most cases the age obtained on the tripeptides glyprohyp and glyproala was in better agreement with the expected age than the original 14 c measurement in some cases the ages of the fractions were similar indicating more of an archaeological than a radiocarbon dating problem we conclude that the use of glyprohyp glyproala is the best solution to date for 14 c dating of contaminated bone samples

energetics of the global ocean the role of layer thickness form drag abstract understanding the role of mesoscale eddies in the global ocean is fundamental to gaining insight into the factors that control the strength of the circulation this paper presents results of an analysis of a high resolution numerical simulation in particular the authors perform an analysis of energetics in density space such an approach clearly demonstrates the role of layer thickness form drag residual effects of hydrostatic pressure perturbations which is hidden in the classical analysis of the energetics of flows for the first time in oceanic studies the global distribution of layer thickness form drag is determined this study provides direct evidence to verify some basic characteristics of layer thickness form drag that have often been assumed or speculated about in previous theoretical studies the results justify most of the previous assumptions and speculations including those associated with i the presence of an oceanic energy cycle explaining the relationship between layer th

accelerator radiocarbon dating at the molecular level molecular level 14c dating is the isolation of specific classes of molecules for their 14c dating by accelerator mass spectrometry ams complex matrices such as fossil bone are difficult to date due to their extreme chemical heterogeneity by isolating individual amino acids contaminants humates are removed and crystalline amino acids result bones with 0 1 0 2 n and collagenous compositions can be dated accurately because structural collagen is present contaminants are removable with xad resin bones with 0 1 n and non collagenous compositions yield dates hundreds to thousands of years too young because most of the preserved organic matter is exogenous accelerator 14c dates on collagenous and non collagenous bones are not comparable due to intrinsic dating inaccuracies ams 14c dating of amino acids demonstrated that 1 post 10 800 year ages for north american megafauna are due to sample contamination not holocene ages on extinct fauna 2 a clovis age 10 900 years was established for a human fossil from the anzick site montana 3 holocene ages cannot be established absolutely for many north american human fossils because the bones were non collagenous 4 accurate ages are attainable on vertebrate fossils as small as passerine birds from pacific island localities 5 well preserved bones are datable without their destruction by extracting protein with water at high temperatures and 6 stratigraphic anomalies to 45 000 years in european upper paleolithic rock shelters are recognizable by dating bone directly

patterns of diagenesis in bone ii effects of acetic acid treatment and the removal of diagenetic co32 abstract archaeological bones of varying preservation have been treated with 0 1 m acetic acid in order to investigate the effect on structural and chemical alterations caused by diagenesis acetic acid is commonly used as a cleaning agent for removing diagenetic carbonate from bone and enamel in an attempt to recover original biogenic signals for use in dietary and14c dating studies diagenetic parameters were measured before and after treatment on a range of archaeological bones with good and bad preservation histological preservation defined the behaviour of the correlating parameters where correlation coefficients between carbonate content and crystallinity microporosity and macroporosity increased significantly after treatment for histologically well preserved material acetic acid is effective at returning carbonate content to around that of modern bone where bone is extensively damaged by micro organisms loose diagenetic material can be removed but a fraction largely composed of hypermineralized bioapatite remains which we believe cannot be reliably used to obtain accurate biological signals

eddy induced heat transport in a coupled ocean atmospheric anomaly model the midlatitude meridional heat transport in the ocean can be partitioned into a transport by the mean flow and an eddy transport this heat transport has been studied in several ocean only models surprisingly it was found that eddy resolving and coarse resolution models have similar total heat transport this is caused by a compensation mechanism in which poleward eddy transport is counterbalanced by an eddy induced meridional circulation recently it was shown that this compensation depends on details of the atmospheric forcing and in fact only occurs for weak thermal coupling where thermal coupling is defined as the rate of change of the surface heat flux with respect to the sea surface temperature sst the thermal coupling varies with the spatial scale of the sst anomaly to study the actual strength of this coupling on the eddy length scale the authors have coupled an isopycnic ocean model with embedded mixed layer to an atmospheric anomaly model by comparing coarse resolution and eddy resolving simulations it is found that 1 the thermal coupling is strong on the eddy length scale and 2 the aforementioned compensation does not occur consequences for the temperature boundary condition in ocean only models the gent and mcwilliams eddy parameterization and climate modeling are discussed

from bone to ash compositional and structural changes in burned modern and archaeological bone abstract the composition and structure of experimentally heated modern bone and cremated bone fragments from various archaeological sites were analysed by fourier transform infrared spectroscopy ftir in attenuated total reflectance atr mode before and after pre treatment with acetic acid the results confirm that time and temperature have an impact on the degree of calcination but also highlight that once fully calcined the final composition and structure of bone are influenced by temperature alone a combination of several infrared indices makes it possible to discriminate between bones cremated under different conditions the study of archaeological samples revealed that their carbonate composition is quite different to modern calcined bone and that some samples originating from high carbonate geological contexts have significantly higher carbonate concentration compared to modern specimens even after pre treatment the results suggest that ftir yields information on not just the structure of burned bone but also potentially about the modes of burning including cremation and the depositional conditions

an exceptional anticyclonic eddy in the south china sea in 2010 the highest sea level near the xisha islands in recent 20 years occurred during august 2010 satellite altimeter data indicated that the extreme event was largely due to an anticyclonic eddy whose amplitude exceeded 20 cm and size exceeded 400 km on 11 august 2010 cruise observations showed the eddy raised the center temperature by 7 7 degrees c at 75 m and vertically extended to 500 m eddy tracking showed it had a life span of more than 8 months and propagated far from the south of xisha islands such strong and long lasting eddy that moved northward for such a long distance was observed for the first time in the south china sea scs observational data from ctd xbt and the reconstructed three dimensional temperature and salinity were used to explore the eddy s features and vertical structure our analyses show the 2010 summer monsoon and current in the western boundary of the scs were largely altered after the 09 10 el nino event from may onward the wind blew northward and strengthened over the northwestern scs such wind drove a strong northward current along the western boundary which carried the eddy northward by advection from may to july energy budget showed during the eddy northward propagation the boundary current passed energy to the eddy which led to the continuing growth of the eddy in both strength and size