seismic investigations along the european geotraverse and its surroundings in central europe since 1975 several high resolution seismic refraction and reflection surveys have been carried out in western germany to investigate the structure of the earth s crust and uppermost mantle the investigation culminated in the seismic refraction survey along the 825 km long central part of the european geotraverse egt in 1986 this contribution summarizes the main results of the more recent crustal investigations along and around the egt the internal crustal structure throughout the area of the variscides is very complex and changes laterally considerably distinct crustal blocks differing in their internal structure can be assigned to geologically defined units of the variscan and caledonian orogeny in spite of local deviations in general a more or less transparent and low velocity upper crust contrasts with a highly reflective lower crust a subdivision of upper and lower crust by a well defined boundary conrad discontinuity is not always seen towards the alps the average velocity of the lower crust is as low as 6 2 km s 1 in contrast to the area north of the swabian jura where the velocities above moho vary between 6 8 and 7 2 km s 1 in northern germany the elbe line separates the lower crust into two regions with 6 4 km s 1 average velocity in the south and 6 9 km s 1 in the north the total crustal thickness under the variscan part of germany is fairly constant between 28 and 30 km except under the rhine graben area with 25 26 km and beneath the central part of the rhenish massif where an anomalous crustal thickening to 37 km is observed under northern germany the moho rises to about 26 km depth and the data indicate at least one fault like step of 1 km before the crust thickens toward the ringkobing fyn basement high the synthesis of seismic velocity structure and petrological information from xenolith studies allows us to propose a mafic composition for the deeper levels of the crust and uppermost mantle which may be valid at least for the central part of the variscan crust along the european geotraverse in central europe

answer to comments on space time structure of monsoon interannual variability the conceptual model proposed by khandekar aims at explaining the occurrence of good or bad indian summer monsoons ism he argues that good or bad monsoon years can be explained by three independent factors el nino southern oscillation enso eurasian snow cover and the stratospheric wind quasi biennial oscillation qbo on the other hand the results in my paper terray 1995 suggest that ism interannual variability is dominated by two low frequency modes the biennial b mode with a period very close to 2 yr and the lowfrequency lf mode with a period close to 4 6 yr the lf mode contains more energy than the b mode but the ocean atmosphere coupling seems to be stronger at the b timescale over the indian ocean finally the occurrence and intensity of exceptional isms depend upon the coupling or the decoupling of the b and lf modes during recent decades it is true that khandekar s model for drought and flood in the indian monsoon has some connections with my results and can be among others a working hypothesis for explaining them however there are still some issues that need to be clarified in khandekar s model from my point of view

global climatic anomalies associated with extremes in the southern oscillation abstract composite temperature and precipitation anomalies during various stages of an event in the southern oscillation so have been computed for several hundred stations across the globe large regions of coherent significant signals are shown to exist for both extremes of the so with warm event signals generally opposite to those during cold events in addition during the year preceding the development of an event in the so year 1 climatic anomalies tend to be opposite to those during the following year year 0 this confirms that the biennial tendency of the so over the pacific indian ocean sectors is also present in more remote regions with climatic signals related to the so many of the signals are consistent enough from event to event to be useful for extended range forecasting purposes

extended eliassen palm fluxes associated with the madden julian oscillation in the stratosphere 1 links are sought between madden julian oscillation mjo related variations in the troposphere and stratospheric circulation tropospheric variations of equatorial mjo filtered 200 hpa zonal winds define indices of mjo activity for two equatorial regions in the indian and western pacific oceans these indices are used to define composite means of mjo filtered extended eliassen palm e p fluxes for eight height levels from the upper troposphere well into the stratosphere evidence is presented for significant and coherent mjo departures throughout the lower stratosphere significant departures of the vertical component of e p flux flow into the lower stratosphere both in the tropics and at higher latitudes especially over canada these are accompanied by horizontal flux departures in the upper troposphere and lower stratosphere from the central tropical pacific into northern canada in this region there is a divergence of extended e p flux piling up wave energy leading to the observed increased cyclonic motion evidence supports the hypothesis that these high latitude circulation variations in the stratosphere are due to a combination of two quite distinct mechanisms in the first poleward propagation occurs in the upper troposphere with vertical propagation at higher latitudes in the second upward propagation occurs in low latitudes into the lower stratosphere this is followed by poleward propagation into higher latitudes and then farther upward propagation

zonal and vertical structure of the madden julian oscillation abstract a statistical study of the three dimensional structure of the madden julian oscillation mjo is carried out by projecting dynamical fields from reanalysis and radiosonde data onto space time filtered outgoing longwave radiation olr data mjo convection is generally preceded by low level convergence and upward motion in the lower troposphere while subsidence cooling and drying prevail aloft this leads to moistening of the boundary layer and the development of shallow convection followed by a gradual and then more rapid lofting of moisture into the middle troposphere at the onset of deep convection after the passage of the heaviest rainfall a westerly wind burst region is accompanied by stratiform precipitation where lower tropospheric subsidence and drying coincide with continuing upper tropospheric upward motion the evolution of the heating field leads to a temperature structure that favors the growth of the mjo the analysis also reveals distinct differences in the vertical structure

topography of the variscan orogen in europe failed not collapsed the variscan orogenic collage consists of three subduction collision systems rheno hercynian saxo thuringian and massif central moldanubian devonian to early carboniferous marine strata are widespread not only in the individual foreland fold and thrust belts but also in post tectonic basins within these foreland belts and on the cadomian crust of peri gondwanan microcontinental fragments which represent the upper plates of the subduction collision zones these marine basins preclude high elevations in the respective areas and also in their neighbourhood widespread late carboniferous intra montane basins with their coal bearing sequences are likewise incompatible with high and dry plateaus while narrow belts with high elevations remain possible along active margins within the orogen comparison of the variscides with the himalaya tibetan plateau is unfounded plausible reasons for the scarcity of high variscan relief include subduction of oceanic and even continental crust subduction erosion orogen parallel extension and most important lithospheric thinning accompanied by high heat flow and magmatism in many areas timing and areal array of magmatism and ht metamorphism are not compatible with a model of tectonic thickening and subsequent gravitational collapse it is suggested instead that lithospheric thinning and heating are due to mantle activities caused by the tethys rift the lower and middle crust were thermally softened and rendered unfit for stacking and isostatic uplift in terms of topography the variscides represent a failed orogen the ht regime also explains the abundance of granitoids and ht lp metamorphic rocks typical of the variscides melting in the ht regime extracted mafic components from variscan and cadomian crust as well as from cadomian metasomatized lithospheric mantle thus mimicking subduction related magmatism the onset of the ht regime at c 340 ma may also have triggered the final ascent of hp uhp felsic metamorphic rocks

the behavior of winter stationary planetary waves forced by topography and diabatic heating abstract a primitive equation linear wave model is developed to examine the effects of mean zonal wind structure on the vertical propagation of stationary planetary waves and to identify the characteristics of the winter stationary waves forced by realistic topography and diabatic heating an analytic mean zonal wind model is used to facilitate changing the wind structure parameters for comparative experiments a more realistic mean wind profile is used to simulate the observed behavior of stationary waves more closely the experiments confirm the sensitivity of vertical wave propagation to the mean wind structure especially to the latitudinal curvature of the mean wind the role of the polar night jet in channeling the planetary waves as they propagate vertically is emphasized at is found that the latitudinal location of the polar night jet also has a significant influence upon the wave propagation a mechanism is proposed to explain the possible connections between the change in the location of the po

southern hemisphere circulation features associated with el nino southern oscillation events abstract composite seasonal mean and anomaly fields prepared from operational numerical analyses have been used to describe the southern hemisphere sh circulation features associated with el nino southern oscillation enso events the period of analyses available 1972 83 has limited the composites to include only three enso events the reliability and stability of the composites has been tested using multiple permutation methods and by comparison with the results obtained using a longer period 1950 79 of sh rawinsonde station data in the sh winter a weak equivalent barotropic wavetrain pattern of anomalies extends over australia and the south pacific ocean to south america this wavetrain pattern is quite variable in amplitude and location between enso events although it is more stable over the subtropical pacific in the sh summer the circulation anomalies are more zonally symmetric with increased height at low and high latitudes and decreased height in middle latitudes the circulation anoma

diurnally modulated cumulus moistening in the preonset stage of the madden julian oscillation during dynamo abstractatmospheric soundings radar and air sea flux measurements collected during dynamics of the madden julian oscillation dynamo are employed to study mjo convective onset i e the transition from shallow to deep convection in the tropical indian ocean the findings indicate that moistening of the low midtroposphere during the preonset stage of the mjo is achieved by simultaneous changes in the convective cloud population and large scale circulation namely cumuliform clouds deepen and grow in areal coverage as the drying by large scale subsidence and horizontal westerly advection wane the reduction of large scale subsidence is tied to the reduction of column radiative cooling during the preonset stage which ultimately links back to the evolving cloud population while net column moistening in the preonset stage is tied to large scale circulation changes a new finding of this study is the high degree to which the locally driven diurnal cycle invigorates convective clouds and cumulus moiste

the tropical extratropical interaction between high frequency transients and the madden julian oscillation abstract the interaction between high frequency transient disturbances and convection and the madden julian oscillation mjo is investigated using ncep ncar reanalysis and satellite outgoing longwave radiation data for 15 northern winters during the phase of the mjo with enhanced convection over the east indian ocean and indonesia and suppressed convection over the south pacific convergence zone both the asian pacific jet and the region of upper tropospheric tropical easterlies over the warm pool are displaced westward these changes in the basic state lead to a weaker or leakier waveguide in the asian pacific jet with a westward displaced forbidden region of tropical easterlies such that high frequency transient waves propagate equatorward into the deep tropics over the central pacific near the date line as these waves induce convection in the region of ascent and reduced static stability ahead of the upper level cyclonic disturbances there is an enhancement of high frequency convective var

the southern oscillation part ix the influence of volcanic eruptions on the southern oscillation in the stratosphere abstract the signal in the winter stratosphere on the northern hemisphere of a warm event in the southern oscillation is a warm polar vortex with a weak westerly circulation this signal failed to appear in two warm events which took place at the time of the eruptions of agung and el chichon we propose that the volcanic emissions affected the development of the warm events in the stratosphere and support this argument by reference to a sensitivity experiment made by m blackmon this experiment used the observed global anomalies of sea surface temperature in december january february 1982 83 but did not consider volcanic aerosols and gasses ejected by el chichon in 1982 the response of the model stratosphere in the experiment resembled the observed signal of the southern oscillation in other years

the retention of primary oxygen isotope compositions of fossil elephant skeletal phosphate fossil elephant remains from sediments of plio pleistocene age in the vicinity of lake turkana kenya provide insights into the ability of the phosphate oxygen system to preserve original 18o values 18op in the depositional environment individual fossil specimens exhibit systematic variations in the 18op values of their various tooth and bone components differences in 18op values between these skeletal components can be as high as 3 6 despite the fact that equivalent phases for individual modern elephants have 18op values which vary by less than 0 6 xrd traces of the different skeletal phases of modern and fossil samples also infer differential preservation of primary apatite crystallinities among the various fossil phases fossil samples of dentine cementum and bone have x ray spectra with sharper and more intense peaks compared to their modern counterparts but little change in crystallinity is observed for fossil enamel samples a model based on the premise that the enamel phase preserves primary isotope signatures and that the accompanying skeletal phases are partially re equilibrated with the fluids associated with the microbial decomposition of the elephant s carcass is consistent with the features of the 18op dataset this isotopic evidence in conjunction with the physical and chemical attributes of enamel has led us to postulate that enamel could be preserving primary isotope signatures while other skeletal components are affected to varying degrees by alteration processes in the burial environment

alteration of enamel carbonate environments during fossilization an understanding of enamel diagenesis is necessary to ensure sound isotopic palaeodietary and palaeoenvironmental reconstructions although carbon isotope signals of browsing and grazing herbivores remain distinct in enamel even after millions of years subtle alteration of isotopic signatures does occur to better understand this change we analysed modern and fossil enamel from a number of south african sites using fourier transform infra red spectroscopy our results indicate that while there is little evidence of increased crystallinity in fossil enamel there is a small but significant change in the proportion of carbonate ions occupying hydroxyl and phosphate sites this seems to occur early in the process of fossilization after which there is no noticeable change it is also important to note that the degree of alteration varies significantly within and between sites we suggest that this change results from one or some combination of three mechanisms exogenous carbonate incorporation endogenous carbonate loss and endogenous carbonate reorganization determining which mechanism s contribute to this alteration is important because all three are likely to affect biogenic carbon isotope ratios differently ftir spectroscopy promises to increase our knowledge of diagenesis and in so doing should improve our palaeodietary and palaeoenvironmental reconstructions

the influence of the 1997 99 el niňo southern oscillation on extratropical baroclinic life cycles over the eastern north pacific the el nino southern oscillation enso strongly influences the interannual and seasonal atmospheric circulation over the north pacific the present study shows that the meridional displacement of the time mean upper level jet associated with enso modulates the time mean barotropic meridional wind shear over the central and eastern north pacific storm track earlier theoretical and observational studies established the influence of barotropic wind shear on the life cycles of extratropical cyclones and their upper level potential vorticity pv waves the present study suggests that differences in the time mean flow associated with the 1997 99 enso cycle had a similar impact on tropopause pv structure meridional eddy fluxes of momentum and temperature and predictability

a dwarf elephant and a rock mouse on naxos cyclades greece with a revision of the palaeozoogeography of the cycladic islands greece during the pleistocene abstract during the late pleistocene naxos and adjacent areas including delos and paros constituted a mega island here referred to as palaeo cyclades the extensive low lying plains with lakes and rivers provided a suitable habitat for elephants due to long term isolation from the mainland and mainland populations these elephants evolved miniature size the species found on naxos had a body size of about ten percent of that of the mainland ancestor palaeoloxodon antiquus during the glacial periods of the late pleistocene p antiquus may have migrated eastwards and southwards in search of better conditions and reached the islands the dwarf species of the various southern aegean islands e g crete tilos rhodos palaeo cyclades are each the result of independent colonisation events the very small size of the naxos species respective to the dwarf elephants from crete is explained as due to the lack of competitors the only other elements of the contemporaneous fauna were a rock mouse apodemus cf mystacinus and a shrew crocidura sp submergence of the area climate change volcanism hunting by humans or a combination of these factors during the terminal pleistocene may have caused the extinction of this endemic fauna

the development of upper tropospheric wind over the western hemisphere in association with mjo convective initiation abstractthis study examines the structure and driving mechanisms of upper tropospheric intraseasonal zonal wind anomalies over the western hemisphere wh during the convective initiation of the madden julian oscillation mjo over the indian ocean using composite and budget analyses the initiating mjo convection is more often associated with wh upper tropospheric intraseasonal easterly wind anomalies and when it is it tends to develop a stronger and zonally broader envelope of enhanced convection than events associated with westerly wind anomalies the wh upper tropospheric zonal wind anomaly associated with the mjo is often described as a dry kelvin wave radiated from mjo convection but the results show that both the structure and driving mechanisms are different from the ones of theoretical kelvin waves unlike the theoretical kelvin wave the zonal wind anomaly is not driven mainly by the zonal pressure gradient force and it is strongly coupled with rotational wind associated with subtropical and

lithospheric cross sections of the european cenozoic rift system abstract the lithospheric structure of the european cenozoic rift system ecris is presented in transects through the southern rhine graben and the rhenish massif hessen depression emphasizing the geophysical structure of the lithosphere based on seismic refraction reflection investigations teleseismic tomography electromagnetic depth sounding models and gravity aeromagnetic earthquake uplift subsidence and heat flow data the rift is clearly expressed in the rhine graben but is not evident at the surface in the area of the rhenish massif where its existence is indicated by seismicity it is characterized by abnormal crustal and upper mantle structures which vary considerably in horizontal direction for example under the rhine graben the crust is thinned to 25 km but at 40 km depth anomalously high velocities are observed in contrast beneath the rhenish massif the crust is thickened to 35 37 km and under its eastern part a high velocity thin upper mantle slice is seen at 30 km depth within the lower crust which towards the hessen depression is gradually replaced by normal variscan mantle with the moho near 30 km depth under the western part of the rhenish massif p and s wave velocities are reduced below 50 km depth which is not seen east of the rhine river under the rhine graben the existence of a low velocity upper mantle above 100 km cannot be generalized but is restricted to confined regions

geochemical and sr nd isotopic characterization of middle pleistocene sediments from the paleontological site of la polledrara di cecanibbio sabatini volcanic district central italy abstract six stratigraphically related samples of freshwater sediments from the middle pleistocene paleontological site of la polledrara di cecanibbio to nw of rome in the sabatini volcanic district svd have been characterized by their mineralogical geochemical and sr nd isotopic compositions these volcaniclastic sediments filled a valley incised by a former watercourse flowing through volcanic rocks the samples are composed of abundant analcite after leucite subordinate augite sanidine fluorite except for the stratigraphically deepest and most sio 2 poor sample and minor anorthite quartz is present only in the stratigraphically uppermost samples the mineralogical composition is consistent with the origin of the sediments from different source rocks of the svd major and trace elements allow for distinguishing among the samples in particular the four stratigraphically uppermost samples share close sio 2 intermediate between the contents of the other two samples although several chemical characteristics of the polledrara samples can be explained by impact of supergene processes on the sediments the overall composition supports an origin from different source rocks of the svd in particular the tufi stratificati varicolori di la storta tfvls and older pyroclastic rocks the 87 sr 86 sr ratios of the samples 0 710182 0 710433 support the distinction of the sediments based on chemistry and mineralogy and their sabatinian origin the isotopic range overlaps that in the lavas of phases iii iv of the svd and is slightly lower than the range in the tfvls likely because of advanced analcitization of the sediments the ammonium acetate extracts from the samples show a narrow isotopic range 0 709613 0 709735 which is lower than the range of the bulk sediments but close to the isotopic composition of fossil elephant remains in the polledrara sediments lastly except for the most sio2 rich sample exhibiting a higher value 0 512227 the 143 nd 144 nd ratios of the other samples show a narrow range 0 512147 0 512171 and cannot be distinguished from each other the isotopic range is similar to that of the tfvls but higher than that of sabatinian lavas supporting the origin of the sediments from the former rocks

intraseasonal temperature variability in the upper troposphere and lower stratosphere from the gps radio occultation measurements 1 in this study we examine the detailed spatiotemporal patterns and vertical structure of the intraseasonal temperature variability in the upper troposphere and lower stratosphere utls associated with the madden julian oscillation mjo using the temperature profiles from the recent global positioning system radio occultation gps ro measurements including the constellation observing system for meteorology ionosphere and climate cosmic mission the mjo related temperature anomalies in the utls are smaller near the equator 1 2 k near the equator the temperature anomalies exhibit an eastward tilt with height from the upper troposphere ut to the lower stratosphere ls and their magnitudes and signs are determined by the strength of convective anomalies and vertical pressure level the subtropical temperature anomalies have similar magnitudes and patterns at a given location between the ut 250 hpa to 150 hpa and the ls 150 hpa to 50 hpa except for opposite signs that change around 150 hpa the subtropical warm cold anomalies in the ut and cold warm anomalies in the ls are typically collocated with the subtropical positive negative tropopause height anomalies cyclones anticyclones and flank or lie to the west of equatorial enhanced suppressed convection we also compare the intraseasonal temperature variability in the utls related to the mjo between the gps ro and atmospheric infrared sounder airs measurements to highlight the new features of the gps ro temperature anomalies and to evaluate the quality of the airs temperature in the utls considering the gps ro temperature in the utls as the benchmark both airs and gps ro have a very consistent vertical structure in the subtropical utls with a high correlation coefficient 0 92 and similar magnitudes both airs and gps ro also show a generally consistent vertical structure of the intraseasonal temperature anomalies in the equatorial utls however gps ro reveals many detailed fine scale vertical structures of the equatorial temperature anomalies between 150 and 50 hpa that are not well captured by airs furthermore the equatorial temperature anomalies are about 40 underestimated in airs in comparison to gps ro over the equatorial indian and western pacific oceans for 250 hpa and over all longitudes for 100 hpa the low sampling within the optically thick clouds and low vertical resolution near the tropopause may both contribute to these deficiencies of airs

northern hemisphere mid winter vortex displacement and vortex split stratospheric sudden warmings influence of the madden julian oscillation and quasi biennial oscillation we investigate the connection between the equatorial madden julian oscillation mjo and different types of the northern hemisphere mid winter major stratospheric sudden warmings ssws i e vortex displacement and vortex split ssws the mjo ssw relationship for vortex split ssws is stronger than that for vortex displacement ssws as a result of the stronger and more coherent eastward propagating mjos before vortex split ssws than those before vortex displacement ssws composite analysis indicates that both the intensity and propagation features of mjo may influence the mjo related circulation pattern at high latitudes and the type of ssws a pronounced quasi biennial oscillation qbo dependence is found for vortex displacement and vortex split ssws with vortex displacement split ssws occurring preferentially in easterly westerly qbo phases the lagged composites suggest that the mjo related anomalies in the arctic are very likely initiated when the mjo related convection is active over the equatorial indian ocean around the mjo phase 3 further analysis suggests that the qbo may modulate the mjo related wave disturbances via its influence on the upper tropospheric subtropical jet as a result the mjo related circulation pattern in the arctic tends to be wave number one wave number two 25 30 days following phase 3 i e approximately phases 7 8 when the mjo related convection is active over the western pacific during easterly westerly qbo phases which resembles the circulation pattern associated with vortex displacement vortex split ssws

tropospheric stratospheric wave propagation during el nino southern oscillation 1 traditional and 3 d extended eliassen palm ep fluxes for the globe between the 3 and 600 hpa levels are used to calculate el nino southern oscillation enso composites few of the warm minus cold departures of the traditional ep fluxes are significant at the 95 confidence level in contrast the enso composite differences of the longitudinally dependent extended ep flux have broad regions of significance for a wide range of latitudes longitudes and heights during an enso event there are significant vertical fluxes of wave energy across the tropopause over the subtropical pacific in addition there is substantial meridional exchange of wave energy in the upper troposphere and lower stratosphere in this region proceeding northward the changes in the stratosphere are associated with meridional exchanges of wave energy and strong vertical fluxes of wave energy across the pacific and north america the higher latitude changes have a westward tilt with height and eastward group velocities both suggesting the importance of rossby waves in the atlantic region there are strong downward fluxes of wave energy which may be part of an important enso pathway into europe overall these results strongly suggest the importance of nonzonally averaged dynamics in the stratospheric responses to enso

a comparison of reanalyses in the tropical stratosphere part 2 the quasi biennial oscillation reanalysis datasets potentially offer the opportunity to examine the tropical quasi biennial oscillation qbo in greater detail than in the past including the associated meridional circulation and the links with other parts of the atmosphere for such studies to be useful the qbo represented by the reanalyses should be realistic in this work the qbo in the era and ncep reanalyses is validated against rawinsonde observations from singapore monthly mean data are used in the lower stratosphere at 50 hpa and 30 hpa the era qbo is reasonable although the wind extrema in both phases are too weak and the vertical shear and the temperature anomalies are too small the ncep qbo is weaker still at 10 hpa neither reanalysis system performs well both systems failing to reproduce the westerlies possibly because of the proximity of the upper boundary the singapore wind is representative of the zonal means in the reanalyses the weak wind extrema in the reanalyses would not support a wave mean flow interaction theory of the qbo because a large portion of the gravity wave spectrum which would be absorbed in reality would be transmitted beyond 10 hpa the stronger shear zones captured in the era data are associated with larger more realistic temperature perturbations near 30 hpa the northward velocities in the ncep data show a more realistic structure than in the era reanalysis where they are dominated by a vertical gridpoint wave structure in the lowermost stratosphere despite the shortcomings of the reanalyses the high correlations of the wind at 30 hpa and 50 hpa with the observations at singapore mean that the reanalyses could potentially be used to examine the effects of the qbo away from the tropical stratosphere future reanalyses need to take full account of the wind shears evident in the rawinsonde observations and use models with an adequate resolution to capture these vertical scales

oxygen isotope analyses of co existing carbonate and phosphate in biogenic apatite a way to monitor diagenetic alteration of bone phosphate abstract the oxygen isotopic composition of phosphate 18 op and structural carbonate 18 oc of hydroxylapatite was determined in 31 bone and tooth samples of modern mammals from different countries these two variables are highly correlate r 2 0 98 and the calculated best fit of linear regression is very similar to the equation calculated from the phosphate and carbonate palaeotemperature equations 1 2 according to previous measurements 3 6 on fossils of different ages from different areas it seems quite improbable to find isotopically altered skeletal remains showing a good correlation between 18 op and 18 oc as is the case with modern samples it therefore seems possible at least in some cases to use these measurements for monitoring fossil bone and tooth diagenetic alteration when a set of points lie on the equilibrium line or close to it the 18 o values could be considered close to the original values in contrast when the points lie to the left or to the right of this line this probably means that the values are diagenetically modified due to interaction with meteoric water or 18 o enriched water respectively

palaeoloxodon exploitation at the middle pleistocene site of la polledrara di cecanibbio rome italy the site of la polledrara di cecanibbio rome central italy clearly documents a close connection between elephant remains and the subsistence strategies of human beings a carcass of a straight tusked elephant was recently discovered in sediments that represent the edge of a former swampy area some limbs are still in anatomical connection and the skeleton is associated with a lithic industry that according to taphonomic data was produced in situ the spatial distribution of elephant bones exceptionally well preserved because of the characteristics of the sediment allows hypothesizing the dynamics of death and burial the almost complete articulated skeleton lies gently bent on its left side though the anterior and posterior limbs maintain a nearly standing position the forelimbs are pointing slightly downward the left hind limb is stretched while the knee of the right one is bent downward with the foot sole facing up the anatomical connection of the bones association excludes any fluvial transport even though some skeletal elements such as vertebrae ribs pelvis and scapulae are missing the carcass belongs to an adult palaeoloxodon antiquus as suggested by the morphological and biometric characteristics of molariform teeth and long bones a large quantity of lithic tools was recovered around the carcass mainly along its right side the presence of more than six hundred lithic implements cores tools flakes and working debris some of them presenting wear traces indicating their use on soft animal tissues meat and hide and associated with the elephant skeleton documents human activity related to the exploitation of the carcass by scavenging the lithic industry on small flint pebbles was produced at the site as indicated by the refitting and by the presence of working debris and indicates very simple chaines operatoires traces of intentional fracturing on the femurs evidence the exploitation on the elephant carcass by humans a marrow extraction and the procurement of raw material for the production of bone tools are also documented by various remains found in sediments deposited during both fluvial and palustrine phases

north grand banks basin offshore newfoundland a sedimentary epeiric basin west of the murre mercury detachment fault abstract the eastern newfoundland offshore area is geologically the best known region of the northwestern atlantic margin extensive geophysical coverage and about 140 exploratory and delineation wells have allowed structural and stratigraphic mapping of a mesozoic rift basin network that includes the south whale whale horseshoe south jeanne d arc carson bonnition jeanne d arc orphan and flemish pass basins a less explored basin not yet targeted by the oil industry and accordingly less explored has recently been discussed in the marine geoscience literature located on the bonavista platform west of the jeanne d arc basin bounding fault and defined here as the north grand banks basin this area has been described from refraction work correlated with deep seismic profiling lithoprobe east data as a possible mesozoic rift basin with hydrocarbon potential or as a palaeozoic basin detected first by gravity measurements but unconfirmed as a rift basin by reflection data this basin is only 2 km deep and contains palaeozoic and probably undeformed mesozoic sedimentary infill its hydrocarbon potential is low the mesozoic sedimentary rocks if present are probably platform carbonates and clastics formed during thermal subsidence episodes following the first two rifting stages that affected the grand banks of newfoundland the placement of the pre rift unconformity within the sedimentary successions of the north grand banks basin and the precise nature of the rocks situated above the avalon basement remain unresolved a geodynamic model involving simple shear extension in the upper crust is used to explain the evolution of newfoundland offshore sedimentary basins including the north grand banks according to this model the basin is located on the upthrown side of the murre mercury fault system that represents the upper crustal expression of a crustal penetrative detachment

relationships among the stratospheric and tropospheric zonal flows and the southern oscillation abstract relationships among the high latitude stratospheric zonal wind the tropospheric zonal wind in the region of the subtropical jet and over the equator the southern oscillation and the stratospheric tropical quasi biennial oscillation qbo were examined from monthly anomaly data for 13 years 1968 80 patterns of correlation wore found which are broadly consistent with the theory on vertical and latitudinal rossby wave propagation with high correlations diminishing rapidly in association with easterly basic flow lag correlations as high as 0 8 0 9 were found for leads of 1 7 months based on three month average anomalies for successive months the simplified lead path is from southern oscillation to equatorial winds to subtropical winds to stratospheric high latitude winds relationships involving the qbo appear weak compared to those involving the extratropical flows the tropospheric equatorial flow of the east pacific and the southern oscillation even so the structure of correlation fo

the southern oscillation part v the anomalies in the lower stratosphere of the northern hemisphere in winter and a comparison with the quasi biennial oscillation abstract the mean anomalies of 50 mb height in the northern winter for seven warm events in the southern oscillation show a weak polar vortex and an enhanced aleutian high in the mean for six cold events the polar vortex is unusually strong and the aleutian high is weakened and displaced far to the southwest these anomalies are consistent with the corresponding anomalies in sea level pressure pattern the warm events of 1963 and 1982 did not fit this pattern as in both years the polar vortex was cold and intense these events happened in years when volcanoes injected large amounts of gases and aerosols into the stratosphere and the temperature of the tropical stratosphere became unusually high in other warm events the temperature of the tropical stratosphere was abnormally low the mean anomalies of the quasi biennial oscillation for the winter as a whole west minus east phase computed from years with no cold or warm events are zonally symmetrical and shaped as four concentric regions with alternatin

characteristics of kelvin waves and gravity waves observed with radiosondes over indonesia profiles of wind velocity and temperature at 0 35 km were observed by means of radiosondes in west java indonesia during november 1992 and april 1993 and used to study the behavior of various atmospheric waves in the equatorial atmosphere an oscillation of zonal winds with a period of about 27 days was found in the troposphere which was associated with variations in humidity and cloud top height kelvin waves showed phase progression beginning at cloud top height 13 16 km and were particularly enhanced near the tropopause the kelvin waves strongly modulated the tropopause structure including the tropopause height minimum temperature and atmospheric stability a hodograph analysis was applied to determine the propagation characteristics of inertial gravity waves height variation of the vertical group velocity suggests that the gravity waves were generated in the troposphere while the horizontal phase velocity distribution suggests that they were interacting with the background mean zonal winds these wave activities were enhanced when tall convective clouds passed over the site suggesting that cumulus convection seems to play a key role in generating these waves in the equatorial region

the southern oscillation in the stratosphere abstract the signal of the southern oscillation in the lower half of the northern hemisphere stratosphere in winter appears to be as follows in the extreme of the southern oscillation when the trade winds are comparatively weak in the south pacific ocean stratospheric geopotential heights and temperatures tend to be higher over the arctic and lower in middle latitudes than in the opposite extreme at the same time the polar night stratospheric jetstream tends to be weaker and the subtropical westerlies to be stronger the conclusions are based on 11 extremes within a 15 year period and on data at standard pressure levels as high as 10 mb

aspects of interannual and intraseasonal variability of the tropopause and lower stratosphere radiosonde and national centers for environmental prediction national center for atmospheric research reanalysis data are utilized to consider aspects of large scale variability in tropopause height temperature and pressure this variability is related to coherent dynamical fluctuations in the troposphere and lower stratosphere through the use of linear correlation and regression on interannual time scales significant global scale tropopause fluctuations are tied to variability in sea surface temperature sst associated with the el ni o southern oscillation phenomenon when sst is anomalously high in the central tropical pacific tropopause height pressure is high low throughout the tropics with largest perturbation amplitudes in the subtropical pacific at the same time the tropopause is cold over the tropical and subtropical pacific sector but warm elsewhere in the tropics over the extratropics wave like perturbations in the tropopause are seen with anomalous cyclonic flow corresponding to a lower tropopause height and higher tropopause temperature and pressure and vice versa the sign of the temperature anomalies in the lower stratosphere tends to match that at the tropopause over much of the globe with opposite signed anomalies in the upper troposphere the vertical structure of these perturbations is consistent with the expected potential vorticity anomalies induced by quasi stationary rossby waves and vertically propagating gravity waves forced by displacements of tropical convection similar relationships are associated with the eastward propprotion of tropical convection due to the madden julian oscillation on intraseasonal time scales

the signature of enso in global temperature and precipitation fields derived from the microwave sounding unit abstract global temperature anomalies associated with enso are investigated making use of a 13 year record of gridded temperature and precipitation data from the microwave sounding unit msu the warm phase of the enso cycle during this period was characterized by an overall warming of the tropical troposphere superimposed upon a distinctive equatorially symmetric dumbbell shaped pattern straddling the equator near 140 w accompanied by negative anomalies along the equator over the western pacific by means of singular value decomposition svd analysis it is shown that this pattern fluctuated in phase with the displacements of convective activity over the equatorial pacific as reflected in the anomalies in outgoing longwave radiation olr and msu precipitation fields fluctuations in mean tropical tropospheric temperature lagged the olr anomalies and the related temperature pattern by about 3 months the same dumbbell shaped pattern was evident with reversed polarity in the lower stratosphere tog

a possible influence of the tropical quasi biennial oscillation on the variability of the extratropical circulation in the southern hemisphere 1 this study uses geopotential heights and zonal winds from the ncar ncep reanalysis and the naujokat tropical stratospheric zonal wind data set to evaluate the suggestion that the tropical quasi biennial oscillation qbo influenced the observed amplitude increase in zonal harmonic wave 1 in the southern hemisphere winter after 1975 fourier analysis was used to extract zonal wave 1 zw1 from the geopotential heights zw1 and the zonal winds were stratified by qbo phase and compared to those composited for years before and after 1975 the comparisons confirm that zw1 during the easterly phase of the qbo is larger than zw1 during the westerly phase the comparisons also suggest that the growth in zw1 seen after 1975 took place preferentially during winters with an easterly tropical qbo and weak stratospheric winds the change in zw1 is associated with surface level changes over the pacific and simultaneous upper level support by the easterly phase tropical qbo

on the quasi decadal modulation of the stratospheric qbo period abstract the length of the westerly phase of the quasi biennial oscillation qbo of zonal wind in the equatorial stratosphere is examined using the longest available record 1950 2001 an earlier finding by salby and callagan of a systematic quasi decadal modulation of the qbo period is confirmed although the earlier suggestion of a strong connection with the solar cycle is less clear in the extended record

mineralogical and geochemical study of granular xenoliths from the alban hills volcano central italy bearing on evolutionary processes in potassic magma chambers granular xenoliths ejecta from pyroclastic deposits emplaced during the latest stages of activity of the alban hills volcano range from ultramafic to salic ultramafic types consist of various proportions of olivine spinel clinopyroxene and phlogopite they show low sio2 alkalies and incompatible element abundances and very high mgo however cr co and sc are anomalously low at a few ppm level olivine is highly magnesian up to fo 96 and has rather high cao 1 ca and very low ni around a few tens ppm contents these characteristics indicate a genesis of ultramafic ejecta by thermal metamorphism of a siliceous dolomitic limestone probably with input of chemical components from potassic magma the other xenoliths have textures and compositional characteristics which indicate that they represent either intrusive equivalents of lavas or cumulates crystallized from variably evolved ultrapotassic magmas one sample of the former group has major element composition resembling ultrapotassic rocks with kamafugitic affinity some cumulitic rocks have exceedingly high abundances of th 81 84 ppm and light rare earth elements lree la ce 421 498 ppm and extreme ree fractionation la yb 288 1393 not justified by their modal mineralogy which is dominated by sanidine leucite and nepheline finegrained phases are dispersed through the fractures and within the interstices of the main minerals semiquantitative eds analyses show that th and lree occur at concentration levels of several tens of percent in these phases indicating that their presence is responsible for the high concentration of incompatible trace elements in the whole rocks the interstitial position of these phases and their association with fluorite support a secondary origin by deposition from fluorine rich fluids separated from a highly evolved potassic liquid the nd isotopic ratios of the cjecta range from 0 51182 to 0 51217 87sr 86sr ratios range from 0 70900 to 0 71036 with the exception of one sample these values are lower than those of the outcropping lavas which cluster around 0 7105 3 this indicates either the occurrence of several isotopically distinct potassic magmas or a variable interaction between magmas and wall rocks however this latter hypothesis requires selective assimilation of host rocks in order to explain isotopic and geochemical characteristics of lavas and xenoliths the new data indicate that the evolutionary processes in the potassic magmas of the alban hills were much more complex than envisaged by previous studies interaction of magmas with wall rocks may be an important process during magmatic evolution element migration by gaseous transfer often invoked but rarely constrained by sound data is shown to have occurred during the latest stages of magmatic evolution such a process was able to produce selective enrichment of th u lree and to a minor degree ta and hf in the wall rocks of potassic magma chamber finally the occurrence of xenoliths with kamafugitic composition points to the existence of this type of ultrapotassic magma at the alban hills

contrasting effects of central pacific and eastern pacific el nino on stratospheric water vapor 1 targeted experiments with a comprehensive chemistry climate model are used to demonstrate that seasonality and the location of the peak warming of sea surface temperatures dictate the response of stratospheric water vapor to el nino in boreal spring el nino events in which sea surface temperature anomalies peak in the eastern pacific lead to a warming at the tropopause above the warm pool region and subsequently to more stratospheric water vapor consistent with previous work however in fall and in early winter and also during el nino events in which the sea surface temperature anomaly is found mainly in the central pacific the response is qualitatively different temperature changes in the warm pool region and specifically over the cold point region are nonuniform and less water vapor enters the stratosphere the difference in water vapor in the lower stratosphere between the two variants of el nino approaches 0 3 ppmv while the difference between the winter and spring responses exceeds 0 5 ppmv

horizontal structure and seasonality of large scale circulations associated with submonthly tropical convection the relationship between deep tropical convection and large scale atmospheric circulation in the 6 30 day period range is examined regression relationships between filtered outgoing longwave radiation at various locations in the tropics and 200 and 850 mb circulation are mapped for the standard seasons and the spatial structure and seasonal dependence of the results are interpreted in view of the basic state circulation in regions where the convection is embedded in upper level easterlies anomalous equatorial easterly flow is typically present at 200 mb within and to the west of the convective signal along with patterns of meridional outflow into subtropical anticyclonic perturbations lagged relationships suggest that the convection is forcing the circulation in many of these cases the outflow and subtropical circulations are strongest into the winter hemisphere during the solstitial seasons with more symmetric signals about the equator seen in the equinoctial seasons the longitudinal positioning of the subtropical features with respect to the convection varies but is generally located due poleward or just to the east of the convection there tends to be a first baroclinic mode vertical structure to these circulations such that equatorial westerlies are present at 850 mb within the convection with closed circulations on either side of the equator resembling equatorial rossby modes especially common over the atlantic and pacific sectors as a contrast in regions located within upper level westerlies or along the margin of influence of upper westerly disturbances convection appears to be forced by upper level wave energy propagating into the deep tropics with the heating located in the upward motion region ahead of upper level troughs this occurs over the atlantic and eastern pacific sectors during northern winter and spring and over australia the south pacific and south america during southern summer when upper westerlies are at relatively low latitudes where they can interact with deep tropical convection the results confirm theoretical and modeling ideas that suggest that rossby wave energy is able to propagate into the deep tropics in regions where upper level westerlies exist in the tropics

the global range of the stratospheric decadal wave part i its association with the sunspot cycle in summer and in the annual mean and with the troposphere abstract the authors correlate the 23 yr series of reanalyzed 30 hpa heights and temperatures and 10 hpa heights with the 11 yr solar cycle for the summers of both hemispheres and for the annual mean the size and spatial pattern of the correlations in the northern hemisphere are the same as those of the correlations computed with a nearly twice as long series from the freie universitat berlin a belt of correlations that encircles the hemisphere in the outer tropics subtropics the correlation pattern is similar in the southern hemisphere the spatial distribution of correlations between 30 hpa temperatures and the solar cycle has the same configuration as the height correlations with the cycle the largest temperature correlations move with the sun from one summer hemisphere to the other the first eigenvector in a principal component analysis of the 30 hpa heights in summer and in the annual mean has the same shape as the above mentioned pattern in the correlations between the stratospheric data and th

tests for diagenesis in tooth enamel esr dating signals and carbonate contents abstract we have tested whether tooth enamel might be altered during burial by focusing on the carbonate content and electron spin resonance esr signals used for dating since oxidized carbon atoms co 2 or co 3 moieties in the apatite lattice give rise to the esr dating signal as a function of absorbed radiation dose inward or outward carbonate mobility would induce changes in the radiation sensitivity of the esr dating signal we used manometry and fourier transform infra red spectroscopy to study carbonate in 11 fossil and five modern tooth enamels from horse cow hippopotamus rhinoceros and mammoth we have shown that ungulate tooth enamel exhibits a narrow range of both carbonate content 4 5 to 5 1 wt and esr signal intensity at 300 gy radiation dose these characteristics are true both for modern and most fossil samples ranging in age up to several hundred thousand years old evidence for possible diagenesis was found only for two samples consisting of fragments of enamel which exhibited anomalous high and low carbonate contents and esr signal sizes

intra tooth study of modern rhinoceros enamel δ18o is the difference between phosphate and carbonate δ18o a sound diagenetic test abstract the carbonate and phosphate oxygen isotopic difference 18 o c p has been suggested as a test for diagenetic alteration of isotope values in fossil apatite samples the generally accepted 18 o c p value for well preserved enamel is 9 only a few studies have focussed on the potential natural variability of this difference in modern and fossil mammal teeth the aim of this study is to document the value of the carbonate phosphate oxygen isotopic fractionation factor co3 po4 at an intra tooth level we measured the enamel phosphate and carbonate oxygen isotopic compositions of two upper molars m1 and m2 of rhinoceros unicornis following a sequence from the apex to the cervix of the crown the average co3 po4 is 1 0082 0 0007 the mean value of the 18 o c p difference is 8 4 0 7 close to the literature values given for other species however we also show that the values of the 18 o c p difference for r unicornis upper molars can vary on a 2 range in the same tooth we develop a physiological model to explain the origin of inter species and intra tooth 18 o c p difference and to understand their implications on the status of 18 o c p as a tool for identifying diagenesis the results imply that by increasing the dataset of phosphate and carbonate oxygen isotopic composition for modern mammal species we will be able to define a maximal and precise envelope corresponding to the well preserved samples and to check a possible species dependence on the 18 o c 18 o p relationship

the high resolution sequence stratigraphy and the mammal fossil record a test in the middle upper pleistocene deposits of the roman basin latium italy abstract in the campagna romana area pleistocene vertebrate fossil remains are preserved both in continental and marine sedimentary successions this fact favoured the identification of faunal complexes in agreement with the biochronologic setting proposed for the plio pleistocene large mammal faunas of the italian peninsula at the same time the detailed facies and sequence stratigraphic analyses carried out in the last years on such deposits have allowed establishment of a regional and local chronostratigraphic framework which sets some physical and temporal limits to the occurrence of faunal complexes in this light the study of the pleistocene deposits of the roman basin based on sequence stratigraphy and mammal biochronology approach can constitute a significant tool to test the relationships among physical stratigraphic units faunal complexes and faunal units in the examined area the fossiliferous levels are essentially found in transgressive fluvial and fluvio palustrine deposits filling incised valleys tst and in highstand barrier island lagoon deposits hst excluding some cases where bones show a probable exhumation process whole discovered mammal remains are mostly coeval with deposits containing them based on taphonomic considerations and on depositional and physical stratigraphic settings a correlation scheme among roman pleistocene sequence stratigraphic units local faunal complexes and italian mammal biochrons is proposed nevertheless many problems remain to be clarified before either the correlation between events and the geochronological framework or the significance and the biochronological value of each faunal assemblage can be considered as definitive

coupling tooth microwear and stable isotope analyses for palaeodiet reconstruction the case study of late middle pleistocene elephas palaeoloxodon antiquus teeth from central italy rome area the identification of mammal palaeodiet is a useful tool for the reconstruction of palaeoenvironmental conditions from the second half of the last century two methodological approaches based on microwear enamel defects produced on tooth enamel by the attrition with food particles and on stable isotope analyses have been of increasing interest the analysis performed on the two sets of elephas palaeoloxodon antiquus falconer and cautley 1847 last molars belonging to late middle pleistocene faunas from la polledrara di cecanibbio and casal de pazzi central italy rome area highlights the possibility of establishing the dietary adaptation of elephants on the basis of a large data set and of a multidisciplinary approach elephants from la polledrara di cecanibbio and casal de pazzi are characterised by prevalently an intermediate type of dietary adaptation grasses leaves bark and coarse stem although the average microwear topographies of the samples are different in the two sets in la polledrara di cecanibbio molars coarse often crossed scratches prevail and pits either large or small occur in about the same percentage as striations the casal de pazzi sample is characterised by a larger number of mixed coarse and fine scratches and a lower percentage of pits for these elephants the amount in their diet of gramineae or vegetables relatively rich in phytoliths was important during the deposition of fossiliferous levels similar features characterised the palaeoenvironment wooded grassland in moderately humid and temperate climate conditions the results of isotope analyses suggest differences in terms of temperature or humidity warmer or more arid conditions for la polledrara than for casal de pazzi taking into account that grazing among elephants may be related to increasing availability of grass during more humid periods whereas browsing is augmented when the grass tend to be withered as reported for extant savannah the different patterns in microwear seem to be consistent with oxygen isotope data carbon isotope measurements on structural carbonate of biogenic apatite enamel suggest a more closed canopy forest at casal de pazzi and more arid climate at la polledrara di cecanibbio strontium isotope composition 87sr 86sr helps to define the geographical area where the two populations were living which is confirmed to be limited to the volcanic province of latium

the bear necessities a new dental microwear database for the interpretation of palaeodiet in fossil ursidae abstract this study presents a new database of dental microwear features for extant bear species which is used to interpret palaeodiet in brown bear ursus arctos from the late middle pleistocene site of grays thurrock u k applying light stereomicroscopy techniques in dental microwear analysis we highlight for the first time that the talonid area of the first lower molar m1 in extant ursids is most effective in the differentiation of dietary ecospaces extant bear species can be separated into different parts of a dietary ecospace revealing microwear features that mirror their dietary preferences of particular note is the differentation of ecospaces within modern brown bear populations from different geographical regions and the potential for identifying seasonal variation in diet the results demonstrate that the diet of thelate middle pleistocene brown bear from the interglacial site of grays thurrock was closely comparable to that of the modern u arctos from northern europe the american black bear ursus americanus and the sun bear helarctos malayanus this suggests the dietary importance of fibrous food as well as soft fruits and invertebrates and a small vertebrate component this finding is in agreement with climatic conditions and habitats inferred for the mis 9 interglacial the creation and testing of a dental microwear database for all modern bear species provides a foundation for subsequent application to other extinct pleistocene bear populations

coupling of the quasi biennial oscillation and the extratropical circulation in the stratosphere through planetary wave transport abstract a significant fraction of the interannual variability of the wintertime stratosphere in the northern hemisphere is related to the quasi biennial oscillation qbo in tropical winds disturbed conditions of the polar night vortex are favored in years when the winds over the equator are easterly more quiescent conditions prevail at high latitudes when the phase of the tropical qbo is westerly the effects of tropical winds on the extratropical circulation are studied in the equivalent barotropic framework on the sphere calculations are performed with the tropical flow representative of easterly and westerly phases of the qbo with planetary wave forcing representative of conditions in the lower stratosphere the wintertime polar vortex is highly disturbed during the easterly phase of the qbo the evolution taking the form of a canadian warming in contrast more quiescent conditions prevail with the same forcing but with tropical winds representative of the westerly phase of the qbo the vortex

the tropical tropopause and the el nino of 1982 1983 an earlier study of the behavior of the tropical tropopause during 1982 is extended through 1984 the earlier study focused on the influence of the el chichon volcanic eruption but it also considered the influence of the 1982 1983 el nino event during its onset phase in the latter half of 1982 here we present anomalies of tropopause height tropopause potential temperature and lower stratospheric potential temperature through 1984 these anomalies clearly show a much warmer than normal tropopause potential temperature over the western tropical pacific associated with el nino the abnormally warm tropopause potential temperature which was evident in late 1982 reaches a peak in early 1983 and continues abnormally warm until about october 1983 during this period the tropopause is also abnormally high but the lower stratospheric potential temperature is near normal

accompanying seismic refraction investigations along the profile dekorp 2 north seismic refraction measurements were carried out along the dekorp 2 n reflection line traveltime data have been inverted to velocity depth distributions using x t inversion und ray tracing methods the velocity model shows alternating layers of high and low velocity high velocity values range from 6 0 to 6 6 km s in the upper crust and from 70 to 8 2 km s in the lower crust in low velocity zones velocities do not exceed 6 25 km s the crust mantle boundary lies in about 28 30 km depth correlations exist between the velocity model of refraction seismics and the line drawing section of reflection seismics

development characteristics and dynamic structure of tropical intraseasonal convection anomalies abstract the development and dynamical structure of intraseasonal low frequency convection anomalies in the equatorial region are investigated using 10 years 1975 85 of outgoing longwave radiation olr and 7 years 1979 85 of 200 and 850 mb wind data the composite olr anomalies for 36 cases show a four stage development process initiation over equatorial africa rapid intensification when passing through the indian ocean mature evolution characterized by a weakening in the maritime continent and redevelopment over the western pacific and dissipation near the date line in moderate events or emanation from the equator toward north america and southeastern pacific in strong events a noticeable feature in vertical structure is that the 850 mb convergence leads convection and midtropospheric upward motion by about 30 degrees longitude in both developing and mature phases equatorial upper lower level easterly westerly anomalies and associated twin anomalous anticyclonic cyclonic circulation an

statistics and dynamics of persistent anomalies abstract persistent anomalies with recurrent spatial patterns play an important role in the atmosphere s low frequency variability we establish a connection between statistical and dynamical methods of description and prediction of persistent anomalies this is done by computing and analyzing the empirical orthogonal functions eofs in a simple deterministic model on the one hand and in southern hemisphere geopotential heights on the other the dynamical model is governed by the fully nonlinear equivalent barotropic vorticity equation on the sphere with simplified forcing dissipation and topography model solutions exhibit persistent anomalies identifiable with blocked zonal and wave train anomalies in northern hemisphere atmospheric data flow structures similar to the patterns above occur as high variance eofs of this nonlinear model the southern hemisphere data we analyze consist in gridded daily maps of 500 mb heights from june 1972 to july 1983 two types of persistent anomalies appear in t

diet reconstructions for end pleistocene mammut americanum and mammuthus based on comparative analysis of mesowear microwear and dental calculus in modern loxodonta africana abstract we analyse mesowear microwear and dental calculus for end pleistocene mammut and mammuthus from north america and modern loxodonta africana to reconstruct diet these three methods allow both short and long term diets to be distinguished as microwear analysis shows a negative correlation between the numbers of pits and scratches counted the proportions of pits pits scratches were used for analyses rather than gross counts the three types of analyses confirm that modern loxodonta africana are grazers or mixed feeders microwear analysis demonstrates that end pleistocene mammut were primarily browsers but may have changed their diets opportunistically or seasonally to graze mesowear analysis of end pleistocene mammuthus indicates a grazing diet but microwear analysis indicates a mixed feeding diet dental calculus analysis demonstrates that all three species were mixed feeding to varying degrees results show that extinct proboscidean diet was more complex than previously thought and may contradict previous work suggesting that mammut were browsers and mammuthus were grazers using mesowear and microwear we found no significant differences in pre and post glacial diet for fossil proboscideans however using dental calculus we found that for pre glacial specimens there was a larger proportion of tiny i e less than 8 m wide grass starch granules whereas for post glacial specimens there is a larger proportion of large i e greater than 20 m wide grass starch granules with lamellae suggesting with a shift in mammut and mammuthus diet during the end pleistocene specimens commonly had different dietary signals depending on the method utilized suggesting that a multi faceted approach is required to fully elucidate proboscidean diet

quasi biennial modulation of the southern hemisphere stratospheric polar vortex observations reveal that the wintertime southern hemisphere stratospheric polar vortex is modulated by the phase of the equatorial quasi biennial oscillation qbo the high latitude southern stratosphere is shown to be slightly colder throughout the winter and the final warming occurs later when the qbo is in its west phase during may october the modulation of winds by the qbo is confined to midlatitudes at the edge of the polar vortex the difference between west and east phase composites of zonal mean wind during november at the time of the final warming in the southern hemisphere exceeded 14 ms 1 this difference is very similar to that in january in the northern hemisphere while northern hemisphere qbo effects are optimized using equatorial winds near 40 hpa southern hemisphere effects are best seen using 25 hpa winds

the generation of global rotational flow by steady idealized tropical divergence abstract tropical convective heating is balanced on the large scale by the adiabatic cooling of ascent the horizontal divergence of the wind above this heating may be viewed as driving the upper tropospheric rotational wind field a vorticity equation model is used to diagnose this relationship it is shown that because of the advection of vorticity by the divergent component of the flow the rossby wave source can be very different from the simple fd source often used in particular an equatorial region of divergence situated in easterly winds can lead to a rossby wave source in the subtropical westerlies where it is extremely effective this part of the source can be relatively insensitive to the longitudinal position of the equatorial divergence a divergence field which is asymmetric about the equator can lead to a quite symmetric rossby wave source for a steady frictionless flow the rossby wave source averaged over regions within closed streamfunction or absolute vorticity contours is under cert

chronology of the palmer deep site antarctic peninsula a holocene palaeoenvironmental reference for the circum antarctic palmer deep sediment cores are used to produce the first high resolution continuous late pleistocene to holocene time series from the antarctic marine system the sedimentary record is dated using accelerator mass spectrometer radiocarbon methods on acid insoluble organic matter and foraminiferal calcite fifty four radiocarbon analyses are utilized in the dating which provides a calibrated timescale back to 13 ka bp reliability of resultant ages on organic matter is assured because duplicates produce a standard deviation from the surface age of less than laboratory error i e 50 years in addition surface organic matter ages at the site are in excellent agreement with living calcite ages at the accepted reservoir age of 1260 years for the antarctic peninsula spectral analyses of the magnetic susceptibility record against the age model reveal unusually strong periodicity in the 400 200 and 50 70 year frequency bands similar to other high resolution records from the holocene but so far unique f

evidence for geographic variation in the diets of late pleistocene and early holocene bison in north america and differences from the diets of recent bison abstract during the late pleistocene and early holocene bison was widely dispersed across north america and occupied most regions not covered by ice sheets a dietary study on bison paleopopulations from alaska new mexico florida and texas was performed using two methods that relate dental wear patterns to diet mesowear analysis and microwear analysis these data were compared to a mixed sample of extant bison from the north american central plains extant wood bison from alberta canada and a variety of other modern ungulates mesowear relates macroscopic molar facet shape to levels of dietary abrasion the mesowear signature observed on fossil bison differs significantly from the hyper abrasive grazing diet of extant bison tooth microwear examines wear on the surface of enamel at a microscopic scale the microwear signal of fossil samples resembles to modern bison but the fossil samples show a greater diversity of features suggesting that fossil bison populations regularly consumed food items that are texturally inconsistent with the short grass diet typical of modern plains bison mesowear and microwear signals of fossil bison samples most closely resemble a variety of typical mixed feeding ungulates all with diets that are substantially less abrasive than what is typical for modern plains bison furthermore statistical tests suggest significant differences between the microwear signatures of the fossil samples thus revealing geographic variability in pleistocene bison diets this study reveals that fossils are of value in developing an understanding of the dietary breadth and ecological versatility of species that in recent times are rare endangered and occupy only a small remnant of their former ranges

intraseasonal behavior of clouds temperature and motion in the tropics abstract the spectral character of tropical convection is investigated in an 11 yr record of outgoing longwave radiation from the advanced very high resolution radiometer to identify interaction with the tropical circulation along the equator in the eastern hemisphere the space time spectrum of convection possesses a broad peak at wave numbers 1 3 and eastward periods of 35 95 days significantly broader than the dynamical signal of the madden julian oscillation mjo this quasi discrete convective signal is associated with a large scale anomaly that propagates across and modulates time mean or climatological convection over the equatorial indian ocean and western pacific outside that region the convective signal is small even though under amplified conditions coherence can be found east of the date line and in the subtropics having a zonal scale of approximately wavenumber 2 anomalous convection propagates eastward at some 5 m s 1 and suppresses as well as reinforces climatological convection

dietary adaptations in an ungulate community from the late pliocene of greece abstract the dietary morphological methods of mesowear and microwear were applied to ungulates of the late pliocene fauna of sesklo thessaly greece the results provide evidence for the predominance of open grassland in the area as the most common species equus stenonis was a strict grazer the rare cervid cf croizetoceros ramosus was the only browser the antelopes genera gazella and gazellospira yielded discrepant microwear and mesowear results this is interpreted as an indication of regional or seasonal dietary resource differentiation inferring that the antelopes were probably mixed feeders that grazed occasionally or periodically

the preservation of glacial interglacial climatic signatures in the oxygen isotopes of elephant skeletal phosphate abstract phosphate 18o values 18op of modern elephant bone and teeth are found to vary linearly according to the 18o of local meteoric water 18omw a parameter with close ties to regional and local climatic conditions enamel dentine cementum and bone separates from individual fossil elephant specimens of late pleistocene age have op values which vary by up to elephant specimens the larger spread in the 18op values of the various skeletal phases for the fossil samples is interpreted as evidence for post depositional alterantion of primary 18op signatures of some if not all of these fossil skeletal components in the fossil samples investigated enamel and dentine phases have systematically lower 18o values than associated bone and cementum phases differential re equilibration with soil waters either by the wholesale replacement of primary apatite or by processes of isotopic exchange is suggested as a mechanism to account for the observed spread in the fossil phosphate 18o data

space time variability of equatorial kelvin waves and intraseasonal oscillations around the tropical tropopause 1 using the ecmwf 40 year reanalysis data large scale variations of temperature and zonal wind around the tropical tropopause are investigated from the space time spectral analysis two dominant spectral regions in the eastward propagating domain are found one for kelvin waves and the other for intraseasonal oscillations isos to investigate activities of kelvin waves and isos we reconstructed the grid data for the two spectral windows and calculated the square amplitude at each grid point kelvin wave activities in zonal wind are vigorous during two seasons around february and july in the upper troposphere up to 100 hpa however the longitudinal maxima are found in the eastern hemisphere at 100 hpa and in the western hemisphere at 150 hpa and below activities calculated from the outgoing longwave radiation data for the kelvin wave spectral window are different from those in zonal wind about their maximum longitudes and seasons as the climatological background zonal wind in the upper troposphere is easterly in the eastern hemisphere and westerly in the western hemisphere it seems that the difference of kelvin wave activities between 100 hpa and 150 hpa is closely related to the background wind field affecting kelvin wave propagation and dissipation iso activities in zonal wind at 100 hpa are vigorous in the western pacific during northern winter and we may find relation to those in olr this indicates that the eastward moving disturbance with the iso time scale is coupled with the organized convective system such as the madden julian oscillation

intraseasonal variations of the tropical total ozone and their connection to the madden julian oscillation we investigate the intraseasonal 30 90 day variations in satellite observed tropical total ozone o 3 and their connection to the madden julian oscillation mjo tropical total o 3 intraseasonal variations are large 10 du and comparable to those in annual and interannual time scales these o 3 anomalies are mainly evident in the subtropics over the pacific and eastern hemisphere and propagate slowly eastward 5 m s 1 the subtropical negative positive o 3 anomalies are typically collocated with the subtropical upper troposphere anticyclones cyclones generated by equatorial mjo convection and flank or lie to the west of the equatorial enhanced suppressed mjo convection the subtropical o 3 are anti correlated with geopotential height anomalies near the tropopause and thus mainly associated with the o 3 variability in the stratosphere rather the troposphere over the equatorial regions total o 3 anomalies are small

thermal excursions in the ocean at the cretaceous tertiary boundary northern morocco δ18o record of phosphatic fish debris c lecuyer p grandjean j r o neil h cappetta and f martineau 1993 thermal excursions in the ocean at the cretaceous tertiary boundary northern morocco c lso record of phosphatic fish debris palaeogeogr palaeoclimatol palaeoecol 105 235 243 high precision oxygen isotope analyses were made of phosphate extracted from 17 samples of nektonic and benthic fish debris sampled across the stratigraphic cretaceous tertiary boundary in northern morocco a refinement of the silver phosphate method was used to isolate phosphate from biogenic materials measured 180 values of 18 6 20 5 o are interpreted as reflecting high resolution thermal variations that affected the ocean water column of the western tethys the warm 27 c water masses that characterized maastrichtian times underwent rapid cooling and stabilized at an average temperature of 19 c during the dano montian and thanetian this period of constant and cool temperature was followed by a relatively rapid but more gradual warming to about 25 c achieved in the middle ypresian significant small shifts in 6180 values between nektonic and benthic fauna recorded only during the stages of rapid warming or cooling may correspond to averaged thermal differences within the water column that developed in response to global climatic changes the indicated temperature distribution could have been caused by thermal changes in the atmosphere rather than some signal carried by deep ocean currents the oxygen isotope data coupled with previous measurements of ree and end ti on the same samples support the suggestion that paleo pacific westward currents progressed as far as the northwestern part of the african platform at the end of the cretaceous period

vertically propagating kelvin waves and tropical tropopause variability abstract the relationship between local convection vertically propagating kelvin waves and tropical tropopause height variability is examined this study utilizes both simulations of a global primitive equation model and global observational datasets regression analysis with the data shows that convection over the western tropical pacific is followed by warming in the upper troposphere ut and cooling in lower stratosphere ls over most longitudes which results in a lifting of the tropical tropopause the model results reveal that these ut ls temperature anomalies are closely associated with vertically propagating kelvin waves indicating that these kelvin waves drive tropical tropopause undulations at intraseasonal time scales the model simulations further show that regardless of the longitudinal position of the imposed heating the ut ls kelvin wave reaches its maximum amplitude over the western pacific this result together with an analysis based on wave action conservation is used to contend

recent large scale changes in the extratropical southern hemisphere atmospheric circulation abstract the zonal anomalies in the 500 hpa geopotential height field of the southern hemisphere are examined using the national centers for environmental prediction national center for atmospheric research reanalyses 1958 96 the zonal anomalies were constructed by removing the zonal mean from each grid point and principal components analysis was performed on the resulting spatial anomalies the principal components of the leading eof of the seasons march april may mam to september october november son indicate that a change has occurred in the extratropical large scale atmospheric circulation of the southern hemisphere it is estimated to have begun after 1975 and is limited to the southern late fall winter and early spring the elements of this change are a deeper pacific trough and higher indian ocean ridge at subtropical latitudes at higher latitudes the ridge over the pacific strengthened and shifted east while troughing occurred in the southwest atlantic weddell sea region consistent wi

clouds associated with the madden julian oscillation a new perspective from cloudsat abstractthe evolution of total cloud cover and cloud types is composited across the madden julian oscillation mjo using cloudsat data for june 2006 may 2010 two approaches are used to define mjo phases 1 the local phase is determined at each longitude and time from filtered outgoing longwave radiation and 2 the global phase is defined using a popular real time multivariate mjo rmm index which assigns the tropics to an mjo phase each day in terms of local phase cloudsat results show a familiar evolution of cloud type predominance in the growing stages shallow clouds coexist with deep intense but narrow convective systems widespread cloud coverage and rainfall appear during the active phases becoming more anvil dominated with time and finally suppressed conditions return results are compared to the convectively coupled kelvin wave which has a similar life cycle to the mjo convection in the mjo tends to be modulated more by moisture variations compared to the kelvin wave in terms of globa

radiosonde observations of equatorial atmosphere dynamics over indonesia 1 equatorial waves and diurnal tides this paper describes the characteristics of the mean winds equatorial waves with periods ranging from 4 to 20 days and diurnal tides determined by analyzing the profiles of wind velocity temperature and humidity obtained every 5 7 hours in the height range up to about 35 km with a height resolution of 150 m during an observation campaign conducted february 27 to march 22 1990 in east java indonesia the structures of the mean winds in the troposphere and lower stratosphere seemed to be affected by the australian monsoon and the quasi biennial oscillation respectively frequency spectra indicated that the equatorial waves as well as the diurnal tides were dominant below about 25 km while gravity waves with periods shorter than 4 days became more significant above 25 km a 7 day oscillation showing an antiphase relation between the eastward and northward components and exhibiting large amplitudes was observed in the lower troposphere the time height variations of the activity of this 7 day oscillation were clearly correlated with a region of high relative humidity perturbations in the zonal wind and temperature with wave periods varying from 15 to 17 days were also enhanced in the troposphere while kelvin waves with periods of about 7 and 20 days were detected in the lower stratosphere and activity near the tropopause was conspicuously enhanced we found that the 20 day kelvin wave greatly modified the structure of the tropopause such as the minimum temperature the tropopause height and the values of the brunt vaisala frequency squared n2 which further suggests the effects of kelvin waves on the transportation of tropospheric water vapor into the stratosphere and on the downward mixing of stratospheric minor constituents into the troposphere the observed profiles of the diurnal oscillation were compared with those of a numerical model assuming only migrating tides which reasonably agreed above about 25 km below 25 km however the observed amplitudes were 1 1 5 m s exceeding those of the model about 10 times moreover the phase profiles involved fluctuations with small vertical scales suggesting interference by many nonmigrating tides with short vertical wavelengths

modeling the quasi biennial oscillation s effect on the winter stratospheric circulation abstract the influence of the equatorial quasi biennial oscillation qbo on the winter middle atmosphere is modeled with a mechanistic global primitive equation model the model s polar vortex evolution is sensitive to the lower stratosphere s tropical winds with the polar vortex becoming more less disturbed as the lower stratospheric winds are more easterly westerly this agrees with the observed relationship between wintertime polar circulation strength and the phase of the qbo in the lower stratosphere in these experiments it is the extratropical planetary rossby waves that provide the tropical extratropical coupling mechanism more easterly tropical winds in the lower stratosphere act to confine the extratropical rossby waves farther north and closer to the vortex at the qbo altitudes weakening the vortex relative to the case of westerly qbo phase while the qbo winds occur in the lower stratosphere the anomaly in the polar vortex strength is strongest at higher levels