relationship between cyclone tracks anticyclone tracks and baroclinic waveguides abstract this study presents observational results concerning the structure and evolution of high frequency fluctuations with periods shorter than 6 days in the geopotential height field the results are based on a statistical analysis of 1000 500 and 250 mb height fields derived from twice daily nmc final analyses over the northern hemisphere for the 20 winters 1964 65 through 1983 84 the disturbances assume the form of waves elongated in the meridional direction with a mean wavelength of 4000 km a westward tilt with height and a mean eastward phase propagation of 12 1 5 m s 1 these results support an interpretation in terms of finite amplitude baroclinic waves whose structure and evolution varies with geographical location over the continents and especially along the eastern slopes of the rockies and the tibetan plateau the waves show marked departures in structure and evolution from those over the oceans in particular we find evidence of a systematic influence of the terrain in steering the

interannual and decadal modulations recently observed in the pacific storm track activity and east asian winter monsoon abstract interannual variability of the north pacific storm track observed over 17 recent winters is documented the local storm track activity is measured by a meridional flux of sensible heat associated with the lower tropospheric subweekly fluctuations the interannual variability in the heat flux over the northwestern nw pacific is found to be strongest in midwinter the first empirical orthogonal function of the interannual variability in midwinter captures the decadal tendency toward the enhanced storm track activity in midwinter over the nw pacific in association with the decadal weakening of the east asian winter monsoon siberian high and the aleutian low that occurred in the late 1980s the most marked signature of this enhancement is that the midwinter minimum in the storm track activity which had been apparent in the early to mid 1980s almost disappeared afterward as opposed to linear theory of baroclinic instability the enhanced activity occurred despite the weakening of the pacific j

poleward deflection of storm tracks an analysis of 11 years of european centre for medium range weather forecasts data focuses primarily on the vertically averaged high frequency transients the conclusions are discussed in the context of a the winter storm track b monthly variability and c interannual variability a winter storm track results show that the pattern of the forcing by the high frequency eddies along the storm track is highly correlated with the stationary circulation and the forcing itself is primarily responsible for the location of the trough ridge system associated with the stationary flow the results also clarify the role of wind component covariance terms u9y9 and y9 2 2 u9 2 in the column averaged vorticity forcing the simpler term u9y9 has the well known effect of intensifying the anticyclonic cyclonic tendencies on the southern northern side of the jet thereby producing an increase in the barotropic component of the zonal jet the y9 2 2 u9 2 term displays a quadrupole pattern which is also approximately in phase with the trough ridge system associated with the stationary flow b monthly variability eddy activity has been shown to possess a seasonal life cycle increasing during the early fall and reaching a maximum around the month of november then decaying for most of the winter months month to month variations in eddy activity over the pacific ocean show that energy levels increase up through november decreasing thereafter at the same time the trough ridge circulation pattern is intensifying by december baroclinicity in the western pacific has increased substantially and low level eddies are found to break by the middle of the ocean upper level eddies start to break well before reaching the west coast of north america resulting in a displacement of the maximum in y9 2 2 u9 2 westward from its november position and increasing the trough ridge forcing by the high frequency eddies c interannual variability wintertime eddy kinetic energy is seen to extend further eastward through the pacific ocean during the warm phase but displays an abrupt termination during the cold phase anomalies in the eddy transient forcing tend to be quite similar to that of the pacific north american pattern itself the extension of the storm track during the warm phase resembles that of fall conditions and is present in the winter season because the source of low level baroclinicity

precambrian mafic dyke swarms in the singhbhum craton eastern india and their links with dyke swarms of the eastern dharwar craton southern india discussion

the middle paleolithic site of cuesta de la bajada teruel spain a perspective on the acheulean and middle paleolithic technocomplexes in europe here we present a pluridisciplinary study of cuesta de la bajada site teruel spain our findings show that the site contains an early middle paleolithic assemblage similar to other european early middle paleolithic industries allowing us to evaluate the coexistence of this industrial tradition with the acheulean technocomplex in southwest europe the process of lithic production at cuesta de la bajada represents a technology focused on debitage the application of technical concepts such as ramified production sequences and the recycling of flakes via the resharpening of tools and exhausted cores this site was formed around a pond not far from a river and contains remains of large macrofauna other than equids and cervids taphonomic analysis highlights the abundance of cut marks on bones and supports the hypothesis of selective hunting by hominids the numerical ages derived from the combination of esr osl and aar dating methods indicate that the archaeological site was very likely formed around the mis 8 mis 9 the appearance of middle paleolithic industries in europe could represents the autochthonous development of a technocomplex distinctly different from the acheulean characterised by chaines operatoires of debitage and a progressive increase of levallois technology and retouched tools these results suggest that there is a clear coexistence of assemblages with acheulean and middle paleolithic industries during the last third of the middle pleistocene at least in the iberian peninsula

an idealized nonlinear model of the northern hemisphere winter storm tracks abstract in this paper a nonlinear dry model forced by fixed radiative forcing alone has been constructed to simulate the northern hemisphere winter storm tracks a procedure has been devised to iterate the radiative equilibrium temperature profile such that at the end of the iterations the model climate closely resembles the desired target climate this iterative approach is applied to simulate the climatological storm tracks in january it is found that when the three dimensional temperature distribution in the model resembles the observed distribution the model storm tracks are much too weak it is hypothesized that this is due to the fact that eddy development is suppressed in a dry atmosphere owing to the lack of latent heat release in the ascending warm air to obtain storm tracks with realistic amplitudes the static stability of the target climate is reduced to simulate the enhancement in baroclinic energy conversion due to latent heat release with this modification the storm tracks in the

seasonal variations in the southern hemisphere storm tracks and jet streams as revealed in a reanalysis dataset abstract regional characteristics of the climatological seasonal variations in southern hemisphere sh storm tracks are examined based on a reanalysis dataset when differences in vertical structure between the subpolar and subtropical jet streams spj and stj respectively are considered the regional characteristics can be interpreted reasonably well from a potential vorticity perspective of baroclinic eddy growth and downstream development of a baroclinic wave packet eddy activity in the upper and lower tropospheres is strongest in the core region of the spj over the eastern south atlantic and indian ocean throughout the year even in austral winter when the intense stj forms over the indian ocean and south pacific showing its eddy driven nature the spj accompanies the strong surface westerlies along a well defined baroclinic zone above an intense oceanic frontal zone in this core region of the storm track low level eddy activity is strongly correlated with the local near surface baroclinicity

geochronological constraints on evolution of singhbhum mobile belt and associated basic volcanics of eastern indian shield abstract the singhbhum mobile belt smb of the eastern indian shield represents a roughly east west trending arcuate belt of folded supracrustals overlying the granite greenstone basement of the singhbhum orissa craton along its northern eastern and western margins and is bounded by the chotanagpur gneissic complex to further north the radiometric ages of the basement singhbhum and equivalent granites and the intrusive anorogenic mayurbhanj granite pluton constrain the time of evolution of this mobile belt between 3 12 and 3 09 ga hence the smb supracrustals also known as singhbhum group is late mesoarchaean in age and not proterozoic as thought earlier the evolution of the smb was followed by emplacement of some major basic igneous rocks within or adjacent to the supracrustals these include simlipal volcanics at 3 09 ga on the smb mayurbhanj gabbro along with mayurbhanj granite at 3 09 ga along the marginal part of the craton near the smb and the dalma volcanics on the smb along with the dhanjori volcanics adjacent to smb at 2 80 ga the 2 80 ga old basic volcanics is also associated with emplacement of some small granite plutons occurring along the marginal part of the craton one of them the tamperkola granite intrudes the smb the 3 09 ga onward igneous activities along the marginal part of singhbhum orissa craton took place essentially under anorogenic tectonic setting before being affected by a major metamorphism at 2 50 ga which is recorded on the dalma volcanics and on some small granite pluton occurs along the marginal part of the craton the jagannathpur and stratigraphically equivalent malangtoli volcanics occurring within the singhbhum orissa craton at the west were erupted at 2 25 ga the boundary between the smb supracrustals and the singhbhum orissa craton is demarked by a prominent shear zone known as the singhbhum shear zone which shows multiple reactivation the oldest being at 3 09 ga followed by subsequent reactivation during palaeo and mesoproterozoic periods at 2 2 1 8 1 6 1 5 1 4 and 1 0 ga respectively the singhbhum group and the adjacent chotanagpur gneissic complex appear to have evolved from a near shore syn rift and a distal post rift stable shelf sedimentary assemblages respectively which were deposited without any stratigraphic break in a marine basin existed in the present north of the singhbhum orissa craton both of these assemblages were deformed and metamorphosed together during proterozoic at 2 5 to 2 3 ga 1 6 ga and 1 0 ga

significance of a midlatitude sst frontal zone in the formation of a storm track and an eddy driven westerly jet abstract in a set of idealized aquaplanet experiments with an atmospheric general circulation model to which zonally uniform sea surface temperature sst is prescribed globally as the lower boundary condition an assessment is made of the potential influence of the frontal sst gradient upon the formation of a storm track and an eddy driven midlatitude polar front jet pfj and on its robustness against changes in the intensity of a subtropical jet stj in experiments with the frontal midlatitude sst gradient as that observed in the southwestern indian ocean transient eddy activity in each of the winter and summer hemispheres is organized into a deep storm track along the sst front with an enhanced low level baroclinic growth of eddies in the winter hemisphere another storm track forms just below the intense stj core but it is confined to the upper troposphere with no significant baroclinic eddy growth underneath the near surface westerlies are strongest near the midlatitude sst front as observe

vertical structure and energetics of the western pacific teleconnection pattern abstractthe western pacific wp pattern characterized by north south dipolar anomalies in pressure over the far east and western north pacific is known as one of the dominant teleconnection patterns in the wintertime northern hemisphere composite analysis reveals that monthly height anomalies exhibit baroclinic structure with their phase lines tilting southwestward with height in the lower troposphere the anomalies can thus yield not only a poleward heat flux across the climatological thermal gradient across the strong pacific jet but also a westward heat flux across the climatological thermal gradient between the north pacific and the cooler asian continent the resultant baroclinic conversion of available potential energy ape from the climatological mean flow contributes most efficiently to the ape maintenance of the monthly wp pattern acting against strong thermal damping effects by anomalous heat exchanges with the underlying ocean and anomalous precipitation in the subtropics and by the effec

characteristics of wave packets in the upper troposphere part i northern hemisphere winter abstract gridded data produced by the ecmwf reanalysis project have been analyzed to document the properties of wave packets in the northern hemisphere winter midlatitude upper troposphere based on results from earlier investigations 300 hpa meridional wind variations were chosen for analysis wave packet envelopes were also defined by performing complex demodulation on the wind data the properties of the wave packets are mainly illustrated using time lagged one point correlation maps performed both on and wave packet envelopes the results show that over most regions in the northern hemisphere winter with the exception of the deep tropics and near the aleutian low medium scale waves dominant wavenumber 5 8 exhibit the characteristics of downstream development and occur within wave trains that propagate with eastward group velocities much faster than the phase speeds of individual phases of the waves their group velocity is highly correlated with the local time mean 200 400 hpa wind while the

response of northern hemisphere storm tracks to indian western pacific ocean warming in atmospheric general circulation models with 40 years integration output of two atmospheric general circulation models gamil iap and hadam3 ukmo forced with identical prescribed seasonally varying sea surface temperature this study examines the effect of the observed indian western pacific ocean iwp warming on the northern hemisphere storm tracks both models indicate that the observed iwp warming tends to cause both the north pacific storm track npst and the north atlantic storm track nast to move northward such a consistent effect on the two storm tracks is closely associated with the changes in the low level atmospheric baroclinicity high level jet stream and upper level geopotential height the iwp warming can excite a wavelike circum global teleconnection in the geopotential height that gives rise to an anticyclonic anomaly over the midlatitude north pacific and a positive phase nao anomaly over the north atlantic these geopotential height anomalies tend to enhance upper level zonal westerly winds north of the climatological jet axes and increase low level baroclinicity and eddy growth rates thus favoring transient eddy more active north of the climatological storm track axes responsible for the northward shift of the both storm tracks the iwp warming induced northward shift of the nast is quite similar to the observed suggesting that the iwp warming can be one of the key factors to cause decadal northward shift of the nast since the 1980s however the iwp warming induced northward shift of the npst is completely opposite to the observed implying that the observed southward shift of the npst since the 1980s would be primarily attributed to other reasons although the iwp warming can have a cancelling effect against those reasons

recognising burnt vein quartz artefacts in archaeological assemblages abstract the primary aims of this study were to determine how vein quartz behaves in an open wood fire and to suggest how burnt quartz may reliably be distinguished from unburnt quartz experimental burning was conducted on 10 50 mm pieces of knapped quartz collected from outcrops and beach cobbles near a later mesolithic and neolithic quartz scatter at belderrig north county mayo ireland burning resulted in considerable fragmentation with the majority of post burning fragments 5 m fluid inclusions in quartz lost their fluid contents often with the development of fluid escape structures and this is likely to be a reliable discriminant between burnt and unburnt vein quartz generally even in the absence of unburnt material for comparison burning also creates microfractures but this feature does not provide a diagnostic test of burning as there is considerable overlap between burnt and unburnt samples in microfracture density

influence of wintertime large scale circulation on the explosively developing cyclones over the western north pacific and their downstream effects 1 the relationships between large scale wintertime circulation and extratropical cyclones that develop explosively the so called bomb cyclones over the western north pacific are investigated using japanese long term reanalysis project data on a monthly basis the east asian winter monsoon variability strongly modulates the bomb cyclone activity in terms of its geographical distribution when the monsoon is strong the bomb cyclone activity tends to concentrate in the vicinity of the kuroshio current and the kuroshio extension near japan while when the monsoon is weak it disperses over the broader areas the enhancement of the monsoon increases the heat and moisture supply from warm currents facilitating unstable conditions within the atmospheric boundary layer and intensifying baroclinicity in the lower troposphere these factors are believed to play a role in inducing bomb cyclones particularly along the warm currents on submonthly timescales the stationary rossby wave propagation along the south asian waveguide serves as a prominent trigger for the rapid reinforcement of synoptic scale disturbances around japan when a pronounced bomb cyclone comes to its mature stage northeast of japan it is capable of exciting stationary rossby waves downstream from the asian jet exit region as vorticity forcing the stationary wave packets developing southeastward across the north pacific ocean basin induce surface cyclogenesis in the vicinity of the hawaiian islands by leading to the equatorward advection of higher potential vorticity from the midlatitudes bringing about the occurrence of kona storms which cause weather hazards in hawaii

a comparison of climatological subseasonal variations in the wintertime storm track activity between the north pacific and atlantic local energetics and moisture effect distinct differences of the storm track jet relationship over the north pacific and north atlantic are investigated in terms of barotropic and baroclinic energetics using ncep 2 reanalysis data for the period of 1979 2008 from fall to midwinter the pacific storm track pst activity weakens following the southward shift of the pacific jet whereas the atlantic storm track ast activity remains steady in position and intensifies regardless of the slight southward shift of the atlantic jet this study is devoted to seeking for the factors that can contribute to this conspicuous difference between the two storm tracks on climatological subseasonal variation by analyzing eddy properties and local energetics different eddy properties over the two oceans lead to different contribution of barotropic energy conversion to the initiation of storm tracks in the north atlantic meridionally elongated eddies gain kinetic energy efficiently from stretching deformation of the mean flow in the jet entrance on the other hand the term associated with shearing deformation is important for the initiation of pst analysis of baroclinic energetics reveals that the intensification of the ast activity in midwinter is mainly attributed to coincidence between location of maximum poleward and upward eddy heat fluxes and that of the largest meridional temperature gradient over slight upstream of the ast the relatively large amount of precipitable water and meridional eddy moisture flux along baroclinic energy conversion axis likely provides a more favorable environment for baroclinic eddy growth over the north atlantic than over the north pacific in the meantime the midwinter minimum of the pst activity is attributable to the southward shift of the pacific jet stream that leads to discrepancy between core region of poleward and upward heat fluxes and that of meridional thermal gradient weakening of eddy mean flow interaction due to eddy shape and reduction of moist effect are also responsible for the weakening of storm track activities in midwinter when the strongest baroclinicity exists over the north pacific

how flakes shatter a critical evaluation of quartz fracture analysis despite its worldwide use as a stone tool raw material quartz is known to be a difficult material for archaeologists the main reason for this is the tendency of quartz flakes to fragment during detachment which complicates the use of traditional lithic analyses in this article we present an experimental study of quartz flake fragmentation we evaluate the method called fracture analysis that has been developed and used explicitly for the study of quartz assemblages the method assumes high predictability of quartz flake fragmentation but our experiments show that there is significant variation in fragmentation that fracture analysis does not take into account our results indicate that this variation is partly explained by indenter hardness the relative thickness of the detached flake as well as individual knapper related factors these results undermine the applicability of quartz fracture analysis in its current form in addition we discuss the effects of flake fragmentation on the technological organisation of prehistoric quartz users and suggest that it has affected reduction strategies as well as blank and tool dimensions we also suggest that there should be mobility related differences in archaeological assemblages in terms of the quality of the quartz raw material and that the curation of quartz should be low in relation to better quality raw materials used parallel with it

vein quartz in lithic traditions an analysis based on experimental archaeology abstract worldwide vein quartz was a commonly used raw material for stone tools but this material has proved difficult for archaeologists to analyse because many quartz assemblages appear to be comprised of amorphous pieces not easily recognised as humanly modified or forming tools this paper discusses the analysis of the debitage focusing on the debitage fragmentation rate the debitage break and fragment types and the quantitative analysis of the complete flakes resulting from experimental knapping of quartz which formed part of a project which investigated the use of quartz in irish prehistoric lithic traditions the results have highlighted the complexity involved in analysing quartz assemblages and the significant differences between the debitage products of quartz and chert knapping assemblages while bipolar knapping is generally easy to differentiate from direct percussion it is harder to differentiate between soft and hard hammer percussion

the annual cycle of northern hemisphere storm tracks part i seasons abstractin this paper and part ii a comprehensive picture of the annual cycle of the northern hemisphere storm tracks is presented and discussed for the first time it is based on both feature trac

bidimensional diagnostics variability and trends of northern hemisphere blocking abstractin this paper northern hemisphere winter blocking is analyzed through the introduction of a set of new bidimensional diagnostics based on geopotential height that provide information about the occurrence the duration the intensity and the wave breaking associated with the blocking this analysis is performed with different reanalysis datasets in order to evaluate the sensitivity of the index and the diagnostics adopted in this way the authors are able to define a new category of blocking placed at low latitudes that is similar to midlatitude blocking in terms of the introduced diagnostics but is unable to divert or block the flow furthermore over the euro atlantic sector it is shown that it is possible to phenomenologically distinguish between high latitude blocking occurring over greenland north of the jet stream and dominated by cyclonic wave breaking and the traditional midlatitude blocking localized over europe and driven by anticyclonic wave breaking these latter events are uniform

the role of the central asian mountains on the midwinter suppression of north pacific storminess abstractthe role of the central asian mountains on north pacific storminess is examined using an atmospheric general circulation model by varying the height and the areas of the mountains a series of model integrations show that the presence of the central asian mountains suppresses the north pacific storminess by 20 30 during boreal winter their impact on storminess is found to be small during other seasons the mountains amplify stationary waves and effectively weaken the high frequency transient eddy kinetic energy in boreal winter two main causes of the reduced storminess are diagnosed first the decrease in storminess appears to be associated with a weakening of downstream eddy development the mountains disorganize the zonal coherency of wave packets and refract them more equatorward as the zonal traveling distance of wave packets gets substantially shorter downstream eddy development gets weaker second the central asian mountains suppress the global baroclinic energy conversion the decre

the impact of wave packets propagating across asia on pacific cyclone development abstract in this paper ecmwf 40 yr reanalysis data have been examined to study the influence of upper level wave packets propagating across asia into the pacific on surface cyclone development over the pacific previous studies have shown that in winter wave packets propagate across asia over two branches a northern branch over siberia and a southern branch along the subtropical jet across southern asia results presented here show that subsequent to the presence of wave packets on either branch the frequency of occurrence of deep cyclones defined as cyclones with central pressure below 960 hpa as well as explosively deepening cyclones those with a deepening rate of 1 bergeron or more are significantly enhanced this enhancement also clearly follows the wave packet eastward as it propagates across the pacific wave packets from the two branches are found to interfere with each other such that if wave packets of the appropriate configuration are present on both the northern and southern branch s

midwinter suppression of baroclinic wave activity in the pacific abstract seasonal variations in baroclinic wave activity and jet stream structure in the northern hemisphere are investigated based upon over 20 years of daily data baroclinic wave activity at each grid point is represented for each day by an envelope function the lowpass filtered time series of the squared highpass filtered geopotential height baroclinic wave activity over the atlantic exhibits a single maximum in january whereas in the pacific it exhibits peaks in late autumn and in early spring and a significant weakening in midwinter which is more evident at the tropopause level than near the surface this suppression occurs despite the fact that the low level baroclinity and the intensity of the jet stream are strongest in midwinter based on the analysis of 31 day running mean fields for individual winters it is shown that over both the oceans baroclinic wave activity is positively correlated with the strength of the upper tropospheric jet for wind speeds up to 45 m s 1 when the strength of t

trampled under foot a quartz and chert human trampling experiment at the cova del parco rock shelter spain abstract an assemblage of 500 385 quartz and 115 chert experimentally knapped artefacts underwent human trampling over the course of two weeks by a team of 10 12 excavators wearing soft soled shoes used while excavating in the rock shelter two zones of trampling were used zone 1 a high artefact density low trampling intensity and lower soil compaction and rockiness and zone 2 a low artefact density high trampling intensity higher soil compaction and rockiness the primary questions were to understand the difference in fracture rates and types between the chert and quartz and the difference between the zones of artefact density trampling intensity and soil density the results have shown that significantly more quartz fractured and were damaged compared to chert and for both materials there was significantly more breakage in the zone with the higher trampling intensity and higher soil compaction and rockiness there was no discerned association between the original artefacts size or weight and the occurrence of breakage of the quartz and chert artefacts except for a very weak association for narrower and thinner quartz artefacts being more likely to break overall there was relatively little horizontal or vertical movement of the artefacts over the two weeks with the largest size ranges moving the most but with no significant difference in the movement of artefacts amongst the smaller size ranges

the early pleistocene stone tools from vallparadis barcelona spain rethinking the european mode 1 abstract the vallparadis site contains a long and continuous archaeological sequence dating to between the late early pleistocene and the first half of the middle pleistocene levels 10 and 10c unit evt7 have yielded abundant macrofauna and mode 1 stone tools calibrated by paleomagnetism and by biostratigraphy to the upper limit of the jaramillo subchron 0 98 ma and by u series esr to 0 83 0 13 ma the industries elaborated from local raw materials are of small size the chaines operatoires used for lithic production are poorly elaborated and are based on an anvil knapping technique shaped tools include notches becs scrapers and denticulates on small pebbles clasts fragments and flakes as well as a large single chopper using a techno typological study and comparisons with other known early pleistocene sites in spain orce and atapuerca and elsewhere in eurasia we propose that these sites belong to an analogous mode 1 techno complex with a variability range the fundamental difference between them lies in the retouched tools because these are poorly represented in europe prior to around 1 ma in contrast orthogonal knapping methods were used in the exploitation of the cores during all this period the successive episodes of interbreeding and independent evolution regarding the phylogenetic reports on the hominin remains from atapuerca would have probably led to regional technological traditions in the european mode 1 lithic record

synoptic behavior of baroclinic eddies during the blocking onset abstract synoptic behavior of individual baroclinic eddies in the course of their interactions with amplifying blocking anticyclones is examined based upon a 30 year record of the tropospheric circulation in the northern hemisphere winter high pass filtered as well as unfiltered fields of geopotential height and potential vorticity were composited relative to the onset of the five different types of blocking patterns before the compositing the entire sequence of the fields was slightly shifted in time and space in such a way that the strongest baroclinic eddy during the onset of each blocking event occupies a prescribed position in the upstream storm track when it reaches its maximum intensity since this shifting considerably reduces the cancellation between the individual high frequency migratory eddies this type of compositing can present a more synoptically oriented view of those interactions than conventional compositing in our composite results one or two pairs of cyclonic and anticyclonic

the early acheulean technology of barranc de la boella catalonia spain abstract since 2007 excavations at barranc de la boella tarragona catalonia spain have revealed three localities with rich archaeo paleontological assemblages la mina el forn and pit 1 palaeontology palaeomagnetism and cosmogenic analyses have dated these localities to close to 1 ma the presence of mammuthus meridionalis hippopotamus antiquus stephanorhinus cf hundsheimensis mimomys savini and victoriamys chalinei stand out in the sample of macro and micro mammals the lithic assemblages from the three sites are made up of percussion cobbles choppers chopper cores cores simple flakes and some retouched flakes mainly denticulates and notches in the case of the el forn and pit 1 localities two large cutting tools have been recovered a cleaver like tool and a pick made of hard wearing schist the lithic assemblage of pit 1 which includes several refitting lithic sets is closely associated with the remains of a young adult mammuthus meridionalis in a clear butchering site context this evidence suggests that barranc de la boella is the oldest european early acheulean site and one of the oldest butchering site on the subcontinent during the late early pleistocene the study of the variability among these three localities in similar environmental conditions together with information from other sites are discussed in order to gain further knowledge about the appearance of the acheulean in europe and its continuity or discontinuity in relation to pre existing technologies

development and decay processes of dual inversion layers in winter over the northwest coast of the south china sea abstractinversion layers in the lower troposphere appear centered at two heights 1 5 and 4 km over the northwestern coast of the south china sea in late boreal winter the mechanisms of these dua

revisiting the esr chronology of the early pleistocene hominin occupation at vallparadis barcelona spain abstract esr dating was applied to fossil teeth and optically bleached quartz grain samples from two units of the sequence at vallparadis barcelona spain weighted mean esr age estimates of 858 87 ka and 849 48 ka were obtained for evt 7 which includes the archaeological level 10 and evt 8 respectively these results are in good agreement with the existing magneto biostratigraphic framework that constrain these deposits between 780 and 990 ka and indicate that vallparadis evt 7 has a chronology very close to that of atapuerca gran dolina td 6 spain

trapping of synoptic scale disturbances into the north pacific subtropical jet core in midwinter 1 over the northwestern nw pacific a subtropical jet stream develops at 30 n in midwinter as the east asian winter monsoon intensifies eddies with subweekly periods propagating through the midlatitude tropopause into the nw pacific storm track tend to be trapped into the jet core 1000 km away from a surface baroclinic zone at 40 n while lifted up by 3 km the trapping appears to weaken the interaction of the upper level eddies with the baroclinic zone thus acting against eddy amplification and thereby contributing to the midwinter minimum in the eddy activity as observed before the late 1980s since then under the reduced trapping effect by the weakened jet upper level eddies tended to propagate right above the surface baroclinic zone while strongly interacting it even in midwinter as in fall and spring this midwinter tendency acted to enhance the eddy amplification that led to the recent disappearance of the activity minimum

the response of the pacific storm track and atmospheric circulation to kuroshio extension variability an index of the kuroshio extension front strength is produced using a maximum covariance analysis between sea surface temperature sst and sea surface height ssh gradient observations and composites of the atmospheric state are presented during its positive and negative phases using reanalysis data 1992 2011 it is found that when the kuroshio extension is less more meandering with a stronger weaker sst front the atmospheric heat transport by transient eddies is increased in the western eastern pacific region consistent with an increase decrease in low level baroclinicity analysis of the eddy mean flow interaction shows that this zonal shift in heat transport forces anomalous barotropic flow in the eastern pacific where blocking frequency is strongly influenced the above relationships cannot be reconciled with the known response of the north pacific storm track to remote forcing from the tropical pacific nor can they be explained by the response of the ocean to atmospheric forcing via surface heat fluxes or winds rather the zonal shift in the storm track highlighted here and the associated changes in the large scale circulation are interpreted as a response to the interannual variability of the kuroshio extension front

the impact of zonal propagation and seeding on the eddy mean flow equilibrium of a zonally varying two layer model this paper investigates the role of zonal propagation for the equilibration of zonally varying flow it is hypothesized that there exist two ideal limits for very small or very large group speed in the first limit the eddies equilibrate locally with the forcing while in the second limit the equilibration can only be understood in a global sense to understand these two limits and to assess which is more relevant for the extratropical troposphere a series of idealized experiments that involves changing the magnitude of the uniform zonal wind is performed the results of the idealized model experiments suggest that the actual troposphere is likely to be in a transition regime between the two limits but perhaps closer to the global than the local limit near the global limit both the eddy amplitude and local baroclinicity over the baroclinic zone are strongly affected by the amount of upstream seeding when the propagation speed is reduced relative to the control run the zonal mean eddy activity decreases because the residence time increases more over the stable part of the channel than along the baroclinic zone with the decrease in upstream seeding the local supercriticality along the baroclinic zone increases although the increase is moderate the decrease in seeding and increase in baroclinicity partially offset the effects of each other leading to only small changes in the maximum eddy amplitude downstream of the baroclinic zone changes in upstream seeding can also be achieved by enhanced damping when the eddies are locally damped the baroclinicity is also enhanced downstream of the damping region due to reduced eddy fluxes for typical parameters the recovery of the eddy amplitude occurs over very long distances based on these idealized results it is argued that the coexistence of enhanced baroclinicity and weaker eddy amplitude over the pacific storm track as compared to the atlantic storm track is consistent with the effects of strong eddy damping over asia

numerical experiments of the storm track sensitivity to oceanic frontal strength within the kuroshio oyashio extensions the sensitivity of the north pacific storm track to midlatitude oceanic frontal strength within the kuroshio oyashio extensions is investigated by applying artificially changed meridional sea surface temperature sst gradients in the weather research forecasting model version 3 4 the result of sensitivity experiments further confirms the close relationship between the storm track activity and meridional sst gradient i e the storm track activity can be intensified as a response to increases in the oceanic frontal strength in order to better understand the mechanism for the storm track intensification due to increased sst gradient velocity temperature correlation and local energetics are analyzed the result indicates that the enhancement of the meridional sst gradient leads to amplitude magnification of eddy meridional velocity and temperature and their phase consistency suggesting that synoptic scale eddies tend to approach the optimum structure for the baroclinic energy conversion which is mainly responsible for the sst front induced enhancement of storm track activity in order to estimate the impact of the oceanic front on the maintenance of the near surface baroclinicity further investigation is made by the composite analysis with the increase in oceanic frontal strength the near surface baroclinicity experiences a slow but strong restoration the increase in the meridional sst gradient results in the intensification in the cross frontal differential sensible heat flux which can more effectively offset the relaxing effect of the transient eddy poleward heat transport

controls on the sr and nd isotopic compositions of hydrothermally altered rocks from the pindos ophiolite greece abstract the sr and nd isotopic behaviour of hydrothermally altered basaltic rocks from the pindos ophiolite nw greece has been investigated samples were obtained mainly from rocks affected by intense hydrothermal alteration in field areas believed to represent hydrothermal discharge zones formed at a mesozoic seafloor spreading centre 87 sr 86 sr ratios in the altered rocks show a narrow range of values intermediate between those of seawater and fresh rock regardless of the degree of alteration this has been interpreted as the result of high overall water rock ratios which were sufficient to produce a homogeneous overprint throughout most of the hydrothermal cell a sr shift index which uses the sr isotopic composition and sr concentration of both rock and fluid has been derived to express the degree of sr exchange between rock and seawater it has been used to investigate the variations in water rock interaction between known hydrothermal systems and to compare ophiolite hosted with modern oceanic systems the results indicate that even when compared on such a uniform basis all the known present day hydrothermal systems are generally more rock dominated than those of pindos and other ophiolites 143 nd 14 nd ratios in the altered rocks are much less markedly affected but may show a shift from original magmatic values the results presented here suggest that this effect cannot simply be attributed to exchange with seawater nd these shifts must result from seawater transporting basaltic nd of a different isotopic composition from elsewhere in the volcanic pile into the zones of intense alteration this study has shown that sr and nd isotopes vary independently as a result of their different original distribution as well as their contrasting geochemical mobility

barranc de la boella catalonia spain an acheulean elephant butchering site from the european late early pleistocene evidence of late early pleistocene elephant butchery activity has been excavated in the pit 1 locality at barranc de la boella catalonia spain the fossil assemblage mainly comprises the remains of one prime adult individual of mammuthus meridionalis together with 125 lithic artefacts among which several refitting groups of chert have been identified the lithic assemblage from the pit 1 locality is composed of cobbles cores simple and retouched flakes together with a large well fashioned pick of hard wearing schist spatial zooarchaeological taphonomic technical and use wear analyses confirm that the occupation was devoted to butchery of the mammoth carcass the activity zone is in a fluvio deltaic area that incises the terrace t 60 of the lower francoli river basin 50 m a s l palaeomagnetic and cosmogenic analyses as well as microfaunal mimomys savini victoriamys chalinei and macrofaunal biostratigraphy mammuthus meridionalis support the timing of the occupation to the late matuyama chron these various lines of evidence point to barranc de la boella being the oldest early acheulean butchering site in europe ongoing excavations at several localities at barranc de la boella are yielding new data on the palaeoenvironmental geochronological and technological framework of these occupations finally the evidence is integrated into current understanding of the subsistence strategies practised by early pleistocene hominins

petrochemistry of the lavas from proterozoic dalma volcanic belt singhbhum eastern india the dalma volcanic belt of the singhbhum precambrian terrain in eastern india is developed along the median zone of a linear basin flanked by archaean cratonic basement to the south the lavas in a low grade metamorphic environment preserve a strong compositional bimodality with highly magnesian picritic volcanics developed at the base and low k basalt flows above constituting the bulk of the lava pile the ultrabasic lavas have low concentrations of immobile incompatible elements ratios of which are probably controlled by the source character dalma mafic flows are closely comparable in geochemical character to modern day mid oceanic ridge basalts morb with a dominance of light ree depleted basalts and ferrobasalts however in terms of certain element ratios th ta deviation from morb characteristics toward island arc tholeiites is apparent in this respect the dalma basalts appear to have a modified morb composition and the closest chemical analogy may be basalts from back arc basins i e a supra subduction zone environment the bimodality of ultrabasic and mafic lavas is reminiscent of archaean komatiitic provinces the geochemical signature of the dalma lavas and the geological framework of the terrain strongly point to a marginal basin domain developed in this crustal segment during the proterozoic

patterns of nd and sr isotopic ratios produced by magmatic and post magmatic processes in the shiant isles main sill scotland the shiant isles main sill of the british tertiary igneous province is a classic example of a differentiated alkaline basic sill four separate intrusions each emplaced internally in rapid succession form a 165 m thick sill hosted by lower jurassic sedimentary rocks extensive nd and sr isotopic studies were conducted on samples from a vertical section through the sill where the relationships of samples to one another are well defined the results illuminate patterns of modification of isotopic ratios and clarify the petrogenesis magma sources crustal contamination magmatic processes bulk mixing interstitial liquid mixing and post magmatic alteration hydrothermal effects on sr and nd overall the whole rock initial 87sr 86sr ratios range from 0 7037 to 0 7061 while initial 143nd 144nd ratios vary from 0 51243 to 0 51286 nd 0 7 to 5 7 values that contrast markedly with those of the country rock acid leaching hcl of the whole rock samples that removes analcime indicates that most of the scatter in the 87sr 86sr is caused by the ubiquitous sub solidus aqueous alteration during which more radiogenic sr was introduced into the sill especially along the margins and also reveals magmatic isotopic ratios in contrast nd was immobile during fluid interaction so that the sill 143nd 144nd ratios were not affected even 1 m from the country rock contact using leached rock values 87sr 86sr and 143nd 144nd ratios are inversely correlated from magmatic processes magmas with two distinct isotopic compositions were involved a more primitive one with 143nd 144nd 0 51285 and 87sr 86sr 0 7035 that produced the first two intrusions and a more evolved one with 0 51252 and 0 7048 that produced the third intrusion mixing of the two magmas was very limited restricted to near contacts between units and apparently occurred by interstitial melt migration the more evolved crinanitic magma was probably produced from a batch of the more primitive picritic melt by a small degree of crustal contamination and crystal fractionation during a short crustal residence prior to ascent and emplacement

seasonal evolutions of atmospheric response to decadal sst anomalies in the north pacific subarctic frontal zone observations and a coupled model simulation abstractpotential impacts of pronounced decadal scale variations in the north pacific sea surface temperature sst that tend to be confined to the subarctic frontal zone safz upon seasonally varying atmospheric states are investigated by using 48 yr observational data and a 120 yr simulation with an ocean atmosphere coupled general circulation model cgcm sst fields based on in situ observations and the ocean component of the cgcm have horizontal resolutions of 2 0 and 0 5 respectively which can reasonably resolve frontal sst gradient across the safz both the observations and cgcm simulation provide a consistent picture between sst anomalies in the safz yielded by its decadal scale meridional displacement and their association with atmospheric anomalies correlated with sst anomalies persistent in the safz from fall to winter a coherent decadal scale signal in the wintertime atmospheric circulation over the north pacific starts emerging in november and develops into an equivalent barotropic an

the anomalous merging of the african and north atlantic jet streams during the northern hemisphere winter of 2010 the north atlantic jet stream during winter 2010 was unusually zonal so the typically separated atlantic and african jets were merged into one zonal jet moreover the latitude height structure and temporal variabilityofthe northatlanticjet duringthis winterweremore characteristic ofthe northpacific this work examinesthe possibility of aflow regime changefrom an eddy driven to a mixed eddy thermally drivenjet a monthly jet zonality index is defined which shows that a persistent merged jet state has occurred in the past both at the end of the 1960s and during a few sporadic months the anomalously zonal jet is found to be associated with anomalous tropical pacific diabatic heating and eddy anomalies similar to those found during a negative north atlantic oscillation nao state a lagrangian back trajectory diagnosis of eight winters suggests the tropical pacific is a source of momentum to the atlantic and african jets and that this source was stronger during the winter of 2010 the results suggest that the combination of weak eddy variance and fluxes in the north atlantic along with strong tropical heating act to push the jet toward a merged eddy thermally driven state the authors also find significant sst anomalies in the north atlantic which reinforce the anomalous zonal winds particularly in the eastern atlantic

early human occupation of iberia the chronological and palaeoclimatic inferences from vallparadis barcelona spain abstract vallparadis is one of the best calibrated and most accurately dated archaeological sites from the european early pleistocene chronological analyses combined with palaeomagnetism esr u series and osl and the biochronology of macro and micromammals are fully consistent and situate the site just above the upper limit of the jaramillo subchron in this article we compare the mandibular first molar m1 of individual adult specimens of mimomys savini recovered from level 10 evt7 at vallparadis with specimens from the stratigraphic sequence at gran dolina atapuerca fuente nueva 3 and barranco leon d orce this comparison allows us to chronostratigraphically relate level 10 at vallparadis with level td5 at gran dolina and to fix the former s chronology to around 0 98 0 95 ma mis 27 and therefore prior to level td6 in which fossil remains of homo antecessor were recovered the chronology of vallparadis and the set of contemporary palaeoclimatic proxies regarding the iberian peninsula strengthen the hypothesis that hominins continuously populated europe at least in iberia throughout the late early pleistocene between the jaramillo subchron and the matuyama brunhes boundary by overcoming the climatic fluctuations and changes to the landscape that occurred during this period

the use of quartz during the lower palaeolithic in northeastern iberia abstract this article analyses the use of quartz as a raw material during the lower palaeolithic in the northeast of the iberian peninsula we studied the use of quartz at 9 sites with chronologies ranging from the end of the early pleistocene to the end of the middle pleistocene quartz was used in all assemblages studied and was always collected close to the sites most of all in the form of pebbles from river basins there was a differential selection of raw materials including quartz according to the technical strategy that humans wanted to implement despite the apparent simplicity of operational schemes carried out using quartz we found factors that point to a remarkable conceptual complexity in the handling of this rock as for example knowledge of the characteristics and mechanical possibilities of quartz and the adaptation of operational schemes to the properties of this raw material

the middle pleistocene site of la cansaladeta tarragona spain stratigraphic and archaeological succession abstract la cansaladeta is a site located in a narrow passage dug out by the francoli river in the pre littoral catalan range ne iberia the archaeological deposit lies on top of a 45 50 m fluvial terrace and contains a rich middle pleistocene stratigraphic succession in which 10 archaeological layers have been identified here we present the description of the sedimentary succession of the site the available chronological framework including tl tt osl and esr u series ages as well as biostratigraphical information the characteristics of the lithotechnical and faunal assemblages as well as the first interpretation of the human occupations at the site three main occupation phases have been differentiated the oldest archaeological layers are embedded in a palaeosol formed on a clayey layer that contains limestone fragments detached from the shelter s wall and roof during the second phase low energy fluvial sediments coming from lateral river floods were deposited and sealed the archaeological layers after a transitional phase the upper layers appear to be derived from slope sediments numerical dating yielded internally consistent dates of 380 400 ka for the sequence however the study of the fossil assemblages potentially suggest a tentative early middle pleistocene age for the lowermost horizons the rich technological record is made up of several local raw materials especially chert but also schist quartzite quartz and other minor rocks knapping sequences seem to be autochthonous as all the elements and size categories of the reduction sequence are present and refits are common techno typological features observed along the sequence are not very diagnostic however the lower layers include some acheulean forms among the large shaped tools restricted variability among the small retouched tools mostly denticulates and a virtually absence of prepared cores the faunal assemblage is scarce and appears strongly altered only the lower layers have provided fruitful information although neither combustion areas nor structures related to fire use have been documented to date heat damage has been repeatedly recorded on both lithic and faunal remains this may point to systematic fire use within the archaeological sequence the data provided by the ongoing excavations at la cansaladeta provide new insight into the early human settlement history of northeast iberia to be reconstructed combining these data with those coming from the close site of barranc de la boella enable us to better reconstruct the timing nature and context of early human occupation in the region