measurements of gravity wave activity within and around the arctic stratospheric vortex lidar measurements of gravity wave activity have been conducted at eureka in the high arctic since 1993 the waves are detected by the fluctuations they induce in temperature it has been found that the amount of wave energy in the upper stratosphere is related to the position of the stratospheric polar vortex in each of the four winters reported here the wave activity was a maximum within the westerly jet at the edge of the vortex a minimum inside the vortex near its centre and intermediate outside the vortex the spectra of wave induced fluctuations show that it is at the longest resolved vertical wavelengths 8 to 15 km that wave energy is being influenced by the background meteorological conditions these findings are interpreted in terms of the doppler shifting and critical level filtering that is imposed by the background wind profile

non uniform psc occurrence within the arctic polar vortex a multi year dataset of lidar measurements of polar stratospheric clouds pscs from two sites in the arctic sodankyla 67 n 27 e and ny alesund 79 n 12 e has been analyzed with respect to the existence temperature of different psc types due to the location of the measurement sites relative to the polar vortex their observations are most of the time representative of vortex edge and vortex center conditions respectively the comparison of the aerosol lidar measurements with local and trajectory temperatures reveals that psc occurrence is favored at the edge of the arctic polar vortex one possibility discussed here is a differential distribution of water vapor that could be responsible for the non uniform threshold temperatures and thus differential psc occurrence within the polar vortex

nitrogen and carbon isotopic composition in the diamonds of mbuji mayi zaire the concentration and isotopic composition of nitrogen measured in large diamonds gram size from the mbuji mayi kimberlite district zaire show a large range of variation 100 n 2100 ppm 11 2 15n 6 0 the15n depleted nitrogen is associated with the higher nitrogen concentrations the large diamonds are individually rather homogeneous in13c range of 13c 0 9 while variations occur within small octahedral diamonds from the same district range up to 5 8 the total range of 13c variation is about the same for the large diamonds 10 5 13c 5 5 the small octahedral diamonds 10 13c 4 6 and the carbonates from local kimberlites 11 8 13c 5 5 the diamond carbon isotopic data could indicate a complex story of crystallization within a deep seated system fractionating its carbon isotopes the nitrogen results indicate that nitrogen in diamonds is on the average markedly depleted in15n weighted average 5 15 relative to atmosphere sediments and upper mantle

noble gas elemental and isotopic abundances in deep sea trenches in the western pacific abstract noble gas elemental and isotopic abundances were measured in seven deep sea water samples from five different sampling sites in the nankai trough the japan trench and the kuril trench the samples were obtained by the manned submersible nautile most of the sampling sites are associated with clam colonies and or fluid venting excesses both in 3 he 4 he ratio and he concentration are observed in a seawater sample collected a few kilometers off the clam colonies which were found at a depth of 3830 m at the mouth of the tenryu canyon concentrations of noble gases ne ar kr and xe in this sample show progressive depletion from ne to xe relative to those in 1 c air saturated seawater which can be attributed to mixing of hot water 15 c with cold ambient water 1 c isotopic compositions of ne ar kr and xe in this sample are atmospheric these observations may reflect venting of hot pore water around the tenryu canyon all the other samples show a significant excess in concentration of all noble gases relative to 1 c air saturated seawater and the isotopic compositions are atmospheric this excess of noble gas concentrations may appear to be air contamination in the samples however results of hydrocarbon analyses of the kaiko samples imply that such large amount of air contamination is improbable decomposition of gas hydrate in deep sea sediments is a more likely explanation for the observed excess of noble gas concentration

search for the mantle nitrogen in the ultramafic xenoliths from san carlos arizona abstract mineral separates olivine ol clinopyroxene cp and orthopyroxene op of ultramafic xenoliths from san carlos have been analyzed for nitrogen and noble gases in an effort to evaluate the isotopic signatures for the sub continental mantle the concentrations of noble gases are generally small but in one clinopyroxene separate cp1 they are about an order of magnitude higher the gases seem mostly to be sited in fluid inclusions elevated isotopic ratios of 20 ne 22 ne 40 ar 36 ar 129 134 136 xe 132 xe with respect to air clearly show the presence of mantle noble gas components in san carlos xenoliths isotopic ratios of xe and ar show that the noble gas systematics in san carlos xenoliths can be explained as a mixture of morb and air like components nitrogen contents in these separates range from 0 1 to 1 5 ppm the 15 n varying from 2 to 5 in totals and from 9 to 10 in the temperature fractions the nitrogen data can be explained by the presence of at least three components a a light nitrogen component 15 n 9 of mantle origin b a heavy nitrogen component 15 n 15 from recycled materials and c an air like nitrogen component 15 n 0 which is incorporated during the emplacement of the host magma while the noble gas isotopic ratios cannot clearly distinguish between an atmospheric and a recycled component 15 n clearly resolves these two using the noble gas and nitrogen isotopic systematics and the end member values from the literature a contribution of 30 to 60 recycled nitrogen component has been estimated in the mantle source region of san carlos xenoliths

nitrogen isotopic compositions and concentrations in marid xenoliths abstract nitrogen isotopic compositions and concentrations in micas from kimberlite hosted marid mica amphibole rutile ilmenite diopside suite of xenoliths from the kimberley area of the kaapvaal craton south africa were measured using continuous flow isotope ratio mass spectrometry and fourier transform infrared spectroscopy fourier transform infrared spectroscopy data suggest that the nitrogen in marid phlogopite is from ammonium in the mica structure the replacement of potassium by ammonium is the major mechanism for the storage of nitrogen within these phlogopites the 15n values of micas from marid xenoliths range from 11 to 9 and nitrogen contents range between 113 and 272 ppm the 15n enrichment of most samples relative to the average upper mantle 15n value of 5 suggests that the nitrogen reflects a recycled reservoir from subducted material within their source region the presence of nitrogen from a recycled reservoir indicates that sedimentary organic nitrogen in the sub continental lithosphere is not effectively cycled to the surface resulting in a geochemically heterogeneous upper mantle

combination of lidar and model data for studying deep gravity wave propagation the paper presents a feasible method to complement ground based middle atmospheric rayleigh lidar temperature observations with numerical simulations in the lower stratosphere and troposphere to study gravity waves validated mesoscale numerical simulations are utilized to complement the temperature below 30 km altitude for this purpose high temporal resolution output of the numerical results was interpolated on the position of the lidar in the lee of the scandinavian mountain range two wintertime cases of orographically induced gravity waves are analyzed wave parameters are derived using a wavelet analysis of the combined dataset throughout the entire altitude range from the troposphere to the mesosphere although similar in the tropospheric forcings both cases differ in vertical propagation the combined dataset reveals stratospheric wave breaking for one case whereas the mountain waves in the other case could propagate up to about 40 km altitude the lidar observations reveal an interaction of the vertically propagating gravity waves with the stratopause leading to a stratopause descent in both cases

nitrogen in rock occurrences and biogeochemical implications 1 there is a growing interest in the role of bedrock in global nitrogen cycling and potential for increased ecosystem sensitivity to human impacts in terrains with elevated background nitrogen concentrations nitrogen bearing rocks are globally distributed and comprise a potentially large pool of nitrogen in nutrient cycling that is frequently neglected because of a lack of routine analytical methods for quantification nitrogen in rock originates as organically bound nitrogen associated with sediment or in thermal waters representing a mixture of sedimentary mantle and meteoric sources of nitrogen rock nitrogen concentrations range from trace levels 200 mg n kg 1 in granites to ecologically significant concentrations exceeding 1000 mg n kg 1 in some sedimentary and metasedimentary rocks nitrate deposits accumulated in arid and semi arid regions are also a large potential pool nitrogen in rock has a potentially significant impact on localized nitrogen cycles elevated nitrogen concentrations in water and soil have been attributed to weathering of bedrock nitrogen in some environments nitrogen released from bedrock may contribute to nitrogen saturation of terrestrial ecosystems more nitrogen available than required by biota nitrogen saturation results in leaching of nitrate to surface and groundwaters and where soils are formed from ammonium rich bedrock the oxidation of ammonium to nitrate may result in soil acidification inhibiting revegetation in certain ecosystems collectively studies presented in this article reveal that geologic nitrogen may be a large and reactive pool with potential for amplification of human impacts on nitrogen cycling in terrestrial and aquatic ecosystems

equations for determining the gas and brine volumes in sea ice samples on a etabli des equations utilisables pour determiner le taux de gaz inclus dans la glace de mer a partir de mesures de densite de salinite et de temperature dans des gammes de temperatures entre 2 c et 30 c inversement ces relations peuvent etre utilisees pour calculer la densite de la glace de mer en fonction de la temperature et de la salinite en prenant en compte a la fois la presence de gaz et de cristaux de sel dans la glace on donne aussi des equations qui permettent le calcul du volume de gaz et d eau salee dans la glace a des temperatures autres que celle pour laquelle la densite a ete determinee

the propagation of mountain waves into the stratosphere quantitative evaluation of three dimensional simulations on 6 january 1992 measurements of a mountain wave with significant amplitude were taken over the southern tip of greenland during an er 2 flight at an altitude of about 20 km this work focuses on 3d numerical simulations of the wave generation and its propagation into the stratosphere during this event the sensitivity of the simulated mountain wave to surface friction and horizontal resolution is explored a nonhydrostatic model is used for experiments with horizontal resolutions of 12 4 and 1 3 km in all simulations the flow over the southern tip of greenland generates a mountain wave which propagates into the stratosphere changes of surface friction and horizontal resolution affect mostly the amplitude of the mountain wave increasing surface friction on the slopes reduces the amplitude of the excited orographic gravity wave horizontal diffusion required for numerical stability attenuates gravity waves during their propagation into the stratosphere increasing the horizontal resolution permits a smaller diffusion and thereby results in larger stratospheric wave amplitudes the experiment with increased surface friction at 1 3 km horizontal resolution shows the best agreement with the observational data of the wave in the stratosphere the differences between the simulated and measured amplitudes of vertical displacement and temperature anomaly are less than about 20 the disparity in vertical velocity is larger downward velocities were observed up to 4 8 m s21 and simulated up to 2 7 m s21 in the experiments with lower surface friction at 4 km resolution the accuracy regarding the amplitude of vertical displacement and temperature anomalies is similar but the simulated maximum downdraft is even weaker the other experiments with increased surface friction at 4 km resolution and normal friction at 12 km resolution significantly underestimate the wave amplitude the results of the experiments suggest that the generation of orographic gravity waves and their propagation into the stratosphere can be simulated in three dimensions in a realistic manner provided that the magnitude of the parameterized surface friction is in a realistic range and the horizontal resolution is sufficient

widespread solid particle formation by mountain waves in the arctic stratosphere observations of polar stratospheric clouds pscs by lidar show that the clouds often contain solid particles which are most likely composed of nitric acid hydrates however laboratory experiments indicate that such hydrate particles are not easily formed under arctic synoptic scale conditions suggesting that solid psc particles should be rather rare here we show results from a model study indicating that mountain induced mesoscale temperature perturbations may be an important source of nitric acid hydrate particles in the arctic multiple arctic vortex trajectories were combined with a global mountain wave forecast model to calculate the potential for solid particle formation during december and january 1994 1995 the mountain wave model was used to calculate adiabatic cooling over several thousand ridge elements nitric acid hydrate particles were assumed to form in the mountain waves according to several microphysical mechanisms and were then advected using polar vortex filling synoptic trajectories to generate maps of solid particle occurrence the calculations show that mountain waves may be a significant source of pscs containing solid particles that are observed on the synoptic scale in particular the east coast of greenland the norwegian mountains and the urals are found to be solid particle sources with the pscs often predicted to survive several thousand kilometers downstream

a three dimensional mountain wave imaged in satellite radiance throughout the stratosphere evidence of the effects of directional wind shear swath scanned thermal radiances from the advanced microwave sounding units amsu a on the noaa and aqua satellites are used to image the horizontal temperature structure of a long wavelength mountain wave that formed over southern scandinavia on 14 january 2003 data from all six stratospheric channels show this wave propagating through the full depth of the stratosphere in channels 9 11 altitudes 20 90 hpa the imaged wave has a phase structure broadly consistent with a stationary wave radiated by the southeastward flow over and above the quasi elliptical terrain of southern norway channel 12 radiances at 10 hpa however show a remarkable abrupt change in imaged wave structure the horizontal wavelength contracts phase lines rotate anticlockwise by 30 40 and peak activity migrates to the south to lie over denmark and northern germany similar structure persists in channels 13 and 14 at 2 5 hpa with progessively increasing radiance amplitudes these features are stable over the 10 hours of amsu a measurements from five separate overpasses and are validated against independent radiances acquired by the atmospheric infrared sounder airs and retrieved airs amsu a temperature profiles from the aqua overpass this change at the channel 11 12 interface coincides with an onset of anticlockwise rotation backing and intensification of background stratospheric winds with height fourier ray and spatial ray modelling incorporating these directionally sheared winds and simplified orographic forcing reproduce the salient features of the observations but only after wave induced temperature perturbations have been converted to channel radiances using a forward model the differential visibility of various components of this three dimensional mountain wave to the amsu a channel weighting functions has a first order impact on the observations at heights above 10 hpa once that is factored in the combined observations and modelling provide direct experimental support for the shutts model s predictions of how backing wind vectors affect the vertical evolution of three dimensional mountain waves implications of these observations for orographic gravity wave drag parametrization are briefly discussed copyright 2007 royal meteorological society

helium neon and argon systematics of the european subcontinental mantle implications for its geochemical evolution in this study we present a comprehensive noble gas study of mantle xenoliths from various european cenozoic volcanic provinces the main body of samples is from the massif central france and the eifel germany smaller subsets of samples are from spitsbergen and the graz basin austria in all the helium neon and argon isotopic abundances of a total of forty five mantle xenoliths phenocrysts and xenocrysts were determined the 3he 4he ratios within each volcanic province are very uniform irrespective of the diverse lithologies and p t conditions which are represented by our sample suite mean 3he 4he ratios of the massif central eifel spitsbergen and kapfenstein are 6 53 25 6 03 14 6 65 25 and 6 1 7 1 times the atmospheric ratio ra respectively the strontium and neodymium isotopic composition of some of the cpx separates are highly variable and therefore in contrast to the uniform he signature we thus conclude that he and probably also the other noble gases in the xenoliths are effectively decoupled from the non volatile elements therefore the he signature that is preserved in the xenoliths is actually that of their host magmas published strontium neodymium and lead isotope data of the unevolved host magmas of the xenoliths correlate well with our xenolith he data the position of the fields of the investigated volcanic provinces in hesr hend and hepb variation diagrams depict ternary mixtures between dmm em himu endmembers as the source the host magmas and their volatiles the neon isotopic composition of the gases released from the xenoliths is in most cases atmospheric and probably reflects atmospheric contamination only a few samples reveal indications for morb type ne or evidence of mass fractionation the 40ar 36ar ratios of the xenoliths are mostly radiogenic with the highest ratio being 17 000 however all samples have suffered a certain degree of atmospheric contamination we calculate that the uncontaminated 40ar 36ar ratio of the european subcontinental mantle is 30 000 the4he 40ar ratios have been fractionated since with values around 0 25 they are below both the current production ratio and the morb ratio they cannot be explained by atmospheric contamination as the samples with high 40ar 36ar ratios also have low 4he 40ar ratios helium and ar were probably fractionated during initial closed system degassing of the host magma we calculate the original unfractionated 4he 40ar ratios of the massif central and eifel magma source which are 2 56 18 and 2 71 17 respectively the noble gas systematics are compatible with the notion that addition of crustal material has modified a former morb source signature we use our mean 3he 4 he ratios and reconstructed 4he 40ar ratios to model the time and degree of contamination of a morb like source with crustal material combining our model with evidence from published oxygen strontium neodymium and lead isotope data we judge that the source of the massif central and eifel magmas became enriched in k u and th shortly prior or during the variscan orogeny pre collisional collisional in this case the enrichment in these elements is therefore most probably related to subduction of crustal material in a destructive continental margin setting

evidence for critical level filtering of atmospheric gravity waves radiosonde measurements were used to investigate gravity wave activity within the lower stratosphere above the canadian high arctic the sondes were launched from the weather station at eureka 80 n 86 w on ellesmere island gravity waves were detected by the fluctuations they induced in temperature and the associated perturbation potential energy density was used to gauge the amount of wave activity it was found that over a 15 month period there were isolated episodes of enhanced wave activity rather than any distinct seasonal cycle profiles of wind velocity were also measured and used here to show that periods of high wave activity occurred only when there would be no or very little critical level filtering of the stationary waves generated by flow over the rough terrain in the vicinity of eureka it was also found that the potential energy spectral density was enhanced at all resolvable scales during the periods of high wave activity

reply to recycled volatiles in mantle derived diamonds evidence from nitrogen and noble gas isotopic data abstract in a reinterpretation of our published rare gas data obtained on polycrystalline diamonds from the orapa kimberlite botswana c e gautheron p cartigny m moreira j w harris and c j allegre evidence for a mantle component shown by rare gases c and n isotopes in polycrystalline diamonds from orapa botswana earth planet sci lett 240 2005 559 572 mohapatra and honda r k mohapatra and m honda recycled volatiles in mantle derived diamonds evidence from nitrogen and noble gas isotopic data earth planet sci lett this issue 2006 claim that mixing between a priori defined proportions of subducted seawater subducted recycled oceanic crust recycled sediments air and the mantle would be more appropriate to account for the observations this view sharply contrasts with our conclusions that the chemical and isotope compositions of rare gases record diamond formation from mantle derived fluid s together with mantle post crystallization radiogenic nucleogenic fissiogenic ingrowth and preferential diffusion of the lightest atoms out of the diamonds in the mantle c e gautheron p cartigny m moreira j w harris and c j allegre evidence for a mantle component shown by rare gases c and n isotopes in polycrystalline diamonds from orapa botswana earth planet sci lett 240 2005 559 572 we present here reasons why the alternative view of mohapatra and honda r k mohapatra and m honda recycled volatiles in mantle derived diamonds evidence from nitrogen and noble gas isotopic data earth planet sci lett this issue 2006 is not supportable

noble gases in mafic phenocrysts and xenoliths from new zealand we have determined the elemental and isotopic compositions of noble gases in young subduction related phenocrystic olivine and clinopyroxene samples from the taupo volcanic zone central north island new zealand and in behind arc intraplate phenocrystic and xenolithic olivine samples from the northland and auckland volcanic provinces northern north island new zealand helium isotopic ratios range from morb like 3he4he values of about 11 10 6 to lower values of about 6 10 6 consistent with previous measurements of helium isotopic ratios in subduction related samples 40ar36ar and 21ne22ne ratios range from atmosphere like compositions to maximum values of about 700 and 0 033 respectively in contrast most of the 21ne22neratios are generally indistinguishable from atmospheric values the variations in helium neon and argon isotopic ratios are interpreted as resulting from mixing of 1 a a primordial 3he rich component derived from the upper mantle and characterised by morb like 3he4he ratios of about 12 10 6 2 b a radiogenic 4he rich component derived from crustal materials and characterised by a 3he4he ratio of less than 2 10 7 and 3 c a helium poor atmosphere derived component which dominates the heavier noble gases by combining the helium and argon isotopic results it is possible to estimate the relative contribution of each of these three components to the total 40ar observed in each sample based on the present understanding of the origin and evolution of arc magmas a simple qualitative model of the mechanisms which introduce noble gases to the parent magmas of the samples is developed however it remains uncertain whether the atmospheric and crustal derived noble gas components are introduced to the mantle source regions of the magmas by subduction or alternatively are introduced by interactions between the ascending parent magmas and the overlying crust

solubility and partitioning of ne ar kr and xe in minerals and synthetic basaltic melts we have measured the solubilities of ne ar kr and xe in natural samples of anorthite diopside forsterite spinel and in synthetic basaltic melts the minerals and melts represent equilibrium pairs in the fo an di sio2 system samples were suspended in individual crucibles in a one bar flowing mixed noble gas atmosphere at 1300 or 1332 c for times ranging from 7 18 days the solubilities in the minerals increase with increasing noble gas atomic number and typical solubility values are surprisingly high samples of a particular mineral i e anorthite that came from different localities yield distinctly different and reproducible solubility values this indicates that properties intrinsic to individual samples can influence solubility noble gases are likely to be sited in lattice vacancy defects in contrast the solubilities in the melts decrease with increasing atomic number our data overlap the low end of the range defined previously for natural basalts however the dynamic range of the values from ne to xe is not as great as for the natural melts solubilities correlate well with melt molar volume but poorly with density the partition coefficients increase with increasing noble gas atomic number for all mineral melt pairs such trends imply that the terrestrial planet atmospheres were not derived from partial melting of chondritic source material significant fractionation of kr relative to xe is not observed ruling out an origin for earth s missing xe via magmatic fractionation partition coefficient absolute values are frequently near or greater than unity for example the ranges for five diopside measurements are the following dnel 0 013 0 37 darl 0 15 0 84 dkrl 0 31 2 4 and dxel 3 2 47 this indicates that magmatic transport is not an efficient mechanism for degassing the terrestrial planets our results favor a catastrophic origin for the atmospheres

recycled volatiles in mantle derived diamonds evidence from nitrogen and noble gas isotopic data abstract noble gas isotopic data from diamonds are commonly interpreted as a two component mixture of gases from the mantle source of mid oceanic ridge basalt morb and air the air like component in diamonds is generally considered to have been acquired secondarily through atmospheric contamination in a recent study c gautheron p cartigny m moreira j w harris c j allegre evidence for a mantle component shown by rare gases c and n isotopes in polycrystalline diamonds from orapa botswana earth planet sci lett 240 2005 559 572 that involved analyses of noble gases carbon and nitrogen such interpretation based on noble gases is used to constrain the sources of carbon and nitrogen in diamond to be solely from the mantle with the help of heavy noble gas and nitrogen isotopic data from diamonds we show here that the air like noble gas component in diamonds is actually a mixture of contributions derived from recycled materials and minor air contamination this in turn suggests that some of the carbon in diamonds may also have a recycled origin

gravity waves and mesospheric clouds in the summer middle atmosphere a comparison of lidar measurements and ray modeling of gravity waves over sondrestrom greenland 1 we conducted gravity wave ray tracing experiments within an atmospheric region centered near the arclite lidar system at sondrestrom greenland 67 n 310 e in efforts to understand lidar observations of both upper stratospheric gravity wave activity and mesospheric clouds during august 1996 and the summer of 2001 the ray model was used to trace gravity waves through realistic three dimensional daily varying background atmospheres in the region based on forecasts and analyses in the troposphere and stratosphere and climatologies higher up reverse ray tracing based on upper stratospheric lidar observations at sondrestrom was also used to try to objectively identify wave source regions in the troposphere a source spectrum specified by reverse ray tracing experiments in early august 1996 when atmospheric flow patterns produced enhanced transmission of waves into the upper stratosphere yielded model results throughout the remainder of august 1996 that agreed best with the lidar observations the model also simulated increased vertical group propagation of waves between 40 km and 80 km due to intensifying mean easterlies which allowed many of the gravity waves observed at 40 km over sondrestrom to propagate quasi vertically from 40 80 km and then interact with any mesospheric clouds at 80 km near sondrestrom supporting earlier experimentally inferred correlations between upper stratospheric gravity wave activity and mesospheric cloud backscatter from sondrestrom lidar observations a pilot experiment of real time runs with the model in 2001 using weather forecast data as a low level background produced less agreement with lidar observations we believe this is due to limitations in our specified tropospheric source spectrum the use of climatological winds and temperatures in the upper stratosphere and mesosphere and missing lidar data from important time periods

origin of air like noble gases in oceanic basalts noble gas studies of oceanic basalts show the ubiquitous presence of an air like component which is usually attributed to a simple atmospheric contamination however simultaneous nitrogen and argon isotopic study shows the presence of heavy nitrogen with an isotopic composition 15n 18 accompanied by 40ar 36ar values much lower than the mantle value such a component can be attributed to recycled materials from subduction zones which are incorporated into these basaltic magmas during their ascent through a shallow enriched region in the mantle this suggests that a part of the air like noble gases in oceanic basalts is due to recycled atmospheric gases thus the air like noble gases in the oceanic basalts hitherto considered a hindrance provide useful clues for understanding the geochemical evolution of these samples

meteorology of the polar vortex spring 1997 the 1996 1997 northern hemisphere spring polar vortex was very strong cold and symmetric somewhat similar to those found in the antarctic spring vortex the vortex did not form until late in december and was very symmetric from february into late april the spring vortex was characterized by record low temperatures record low ozone amounts as measured from the total ozone mapping spectrometer toms instruments and a wide band of strong winds in the lower stratosphere spring wave activity was greatly reduced with 100 hpa february march eddy heat fluxes that were lower by a factor of 2 from any previously observed values over the last 18 years

relevance of mountain wave cooling for the formation of polar stratospheric clouds over scandinavia mesoscale dynamics and observations for january 1997 the effect of mesoscale mountain wave induced temperature anomalies on the formation potential of polar stratospheric clouds above northern scandinavia is analyzed with a one month mesoscale model integration the simulation results are contrasted with synoptic scale analyses and compared with remote sensing and in situ observations the mesoscale mass flux of air parcels with temperatures below the threshold for cloud formation through a control volume is compared with its synoptic scale counterpart a classification of the synoptic scale flow into periods of large and small mountain wave activity in the stratosphere is proposed the derived classification will be used for a climatology of stratospheric mountain wave activity above scandinavia

isotopic variations of the fixed nitrogen in metamorphic rocks the content and isotopic composition of fixed nitrogen nh 4 n in metasedimentary rocks phyllites mica schists and gneisses from prograde metamorphic zones in the erzgebirge saxon ore mountains g d r were measured and show that the nitrogen content decreases and 15n increases with increasing metamorphic grade the geochemical and isotopic behaviour of nitrogen during contact metamorphism was investigated in a mica schist profile through the contact aureole of a granitic pluton the nitrogen concentrations of the wall rocks decrease towards the contact whereas the 15n values become higher various model experiments were carried out in the laboratory to explain the changes observed in the rock samples the nitrogen isotope fractionation factor was determined for the isotopic exchange in the system ammonium sulphate ammonia at 250 c 1 0143 0 0012 and 350 c 1 0128 0 0006 in accordance with the model experiments the conclusion seems warranted that the change in nitrogen content and its isotopic composition in rocks during metamorphic processes depend mainly on the metamorphic temperature

global observations of gravity waves from high resolution dynamics limb sounder temperature measurements a yearlong record of temperature amplitude and vertical wavelength 1 global observations of gravity waves have been performed using the high resolution dynamics limb sounder hirdls temperature data a background field that was derived by dynamically calculating 31 day 15 day means to block the stationary component and the slowly varying planetary scale waves was first subtracted from the hirdls temperature measurements an additional step was then taken to remove rapidly moving planetary scale waves by developing an along track temperature filter which was created by averaging the profiles within a 1000 km along track window finally each individual temperature perturbation vertical profile was analyzed using a fast fourier transform to estimate gravity wave temperature amplitudes and vertical wavelengths the investigation of the monthly mean gravity wave temperature amplitudes for the year 2006 found that gravity wave activity in the stratosphere is highly variable with season and can be very orographically dependent especially in the winter extratropics the monthly zonal means show that the peak vertical wavelengths correspond closely to the peak amplitudes the increasing amplitudes and vertical wavelengths are faster and generated at lower altitudes in the winter extratropical and high latitude stratosphere than those in the summer tropical stratosphere this is consistent with the lower source altitudes of orographic gravity waves in the extratropics and high latitudes and the higher source altitudes of convectively generated gravity waves in the tropics three cases were studied for the observed gravity waves over large mountain ranges using the european centre for medium range weather forecasts wind data investigations of episodes of enhanced gravity wave activity over the southern andes the cascade range and the rockies in winter months of 2006 indicate that orographic gravity waves refract downwind from the mountains and propagate along the direction of the intense winds by way of contrast observations of gravity waves around the himalayas show a strong relationship with the cyclones in that region

nitrogen isotopic composition of the morb mantle a reevaluation 1 nitrogen in the mantle source of mid oceanic ridge basalts morbs is commonly believed to have 15n 5 this is based on a selective statistical average drawn from nitrogen isotopic data obtained simultaneously with argon from morbs however on critical evaluation using the accompanying 40ar 36ar data we show this approach to be somewhat ambiguous considering the fact that morbs can have a number of geochemical components in them as has been shown by several recent studies the approach of statistical averaging may actually point to a mixture rather than the true mantle end member a more reasonable approach also used for deriving the mantle noble gas signatures suggests nitrogen in the morb mantle to be much lighter 15 in its isotopic composition such a signature is consistent with nitrogen data from morbs as well as from other mantle derived samples that are believed to have sampled volatiles from the morb mantle

nitrogen 15 enriched precambrian kerogen and hydrothermal systems 1 nitrogen isotope data are reported for kerogen from precambrian black shales at prehnite pumpellyite to greenschist facies and for micas from postmetamorphic hydrothermal quartz vein systems nitrogen in micas was acquired from n bearing aqueous metamorphic hydrothermal fluids generated from breakdown of sedimentary kerogen and dehydration of k silicates at deeper crustal levels the 2 7 ga kerogens and hydrothermal k micas yield 15n values of 15 24 compared to existing data of 2 6 in phanerozoic counterparts paleoproterozoic equivalents have intermediate 15n of 7 12 implying a secular decrease in 15n of shale kerogen the 15n enriched nitrogen in archean shales and hydrothermal vein systems cannot be caused either by n isotopic shifts accompanying metamorphism or rayleigh fractionation because premetamorphic and postmetamorphic samples from the same terrane are both enriched and lack covariation of 15n with n c n ratios or metamorphic grade the magnitude of shifts during progressive metamorphism of sedimentary rocks in previous studies is constrained at 1 to greenschist and about 3 to amphibolite facies furthermore 15n enriched values cannot stem from long term preferential diffusional loss of 14n as samples were selected from terranes where 40ar 39ar ages are within a few million years of concordant u pb ages nitrogen is structurally bound in micas whereas ar is not it is possible that the 15n enriched values stem from a different n cycle in the archean with large biologically mediated fractionations yet the magnitude of the fractionations observed exceeds any presently known and chemoautotrophic communities tend to depleted values earlier results on archean cherts show a range from 6 to 30 given the temporal association of chert banded iron formation with mantle plumes the range is consistent with mixing between mantle n2 of 5 and the enriched marine reservoir identified in this study we attribute the secular trend from archean kerogen of 15 24 to phanerozoic kerogen averaging 3 4 to a secondary atmosphere derived from ci chondrite like material and comets with 15n of 30 42 shifts of 15n to its present values of 0 can be accounted for by a combination of sequestration of atmospheric n2 into sedimentary rocks and mantle degassing of 5 mantle n2

noble gases in ultramafic xenoliths from san carlos arizona this work reports the results of noble gas ne ar kr xe analyses of accidental mantle xenoliths from san carlos arizona except for the addition of radiogenic 40ar and mass fractionation effects the isotopic structures of these gases are indistinguishable from atmospheric composition the absence of 129xe excesses in these rocks may reflect indirect mixing of atmospheric gases with the source region of the xenoliths the dominant influence on the noble gas abundances in the san carlos xenoliths appears to have been diffusive gas loss which may have occurred in a mantle metamorphic event or during contact with the host basanite magma evidence is presented for the partitioning of significant amounts of the heavy noble gases into fluid inclusions in the xenolith minerals the proportion of each gas in the inclusions increases with increasing atomic weight of the gas possibly reflecting solubility effects the noble gases are present in greater concentration in pyroxenes than in olivine similar to the behavior of other incompatible elements

15n 14n variations in cretaceous atlantic sedimentary sequences implication for past changes in marine nitrogen biogeochemistry at two locations in the atlantic ocean dsdp sites 367 and 530 early to middle cretaceous organic carbon rich beds black shales were found to have significantly lower 15n values lower15n 14n ratios than adjacent organic carbon poor beds white limestones or green claystones while these lithologies are of marine origin the black strata in particular have 15n values that are significantly lower than those previously found in the marine sediment record and most contemporary marine nitrogen pools in contrast black organic carbon rich beds at a third site dsdp site 603 contain predominantly terrestrial organic matter and have c and n isotopic compositions similar to organic matter of modern terrestrial origin the recurring15n depletion in the marine derived cretaceous sequences prove that the nitrogen they contain is the end result of an episodic and atypical biogeochemistry existing isotopic and other data indicate that the low15n relative abundance is the consequence of pelagic rather than post depositional processes reduced ocean circulation increased denitrification and hence reduced euphotic zone nitrate availability may have led to cretaceous phytoplankton assemblages that were periodically dominated by n2 fixing blue green algae a possible source of this sediment15n depletion lack of parallel isotopic shifts in cretaceous terrestrially derived nitrogen site 603 argues that the above change in nitrogen cycling during this period did not extend beyond the marine environment

observations and simulations of a large amplitude mountain wave breaking over the antarctic peninsula 1 a case study of a large amplitude orographic gravity wave occurring over the antarctic peninsula is presented based on observations from the vorcore balloon campaign and on mesoscale numerical simulations the vorcore campaign september 2005 to february 2006 consisted in the flight of 27 superpressure balloons in the core of the southern hemisphere stratospheric polar vortex at altitudes of 16 19 km from september 2005 to february 2006 on 7 october 2005 one of the balloons exploded as it was flying above the antarctic peninsula the observations collected by another balloon that was flying during the same time period above the peninsula suggest the presence of a very intense gravity wave peak to peak amplitude of the order of 25 30 m s 1 in zonal and meridional velocity disturbances the wave packet is likely undersampled in the balloon observations because of its high intrinsic frequency but the balloon data set is complemented with high resolution numerical simulations carried out with the weather research and forecast model the simulations are validated by comparison with the balloon measurements and show that the wave was breaking in the lower stratosphere at the time and height where the balloon exploded the simulations highlight several consequences of the mountain wave on the stratosphere forcing of the mean flow generation of secondary inertia gravity waves and turbulence and mixing in particular the momentum fluxes are calculated and are found to compare well with the estimates from balloon measurements the large values found are likely extreme values which raises the issue of their representativity to discuss this the balloon measurements are used in conjunction with operational analyses to estimate the frequency of such large amplitude gravity waves i e to provide an estimate of their intermittency

a re assessment of the nitrogen geochemical behavior in upper oceanic crust from hole 504b implications for subduction budget in central america abstract the geochemical behavior of n during seawater oceanic crust alteration remains poorly constrained yet it is a central parameter to assess the flux of n to subduction zones most studies proposed that hydrothermally altered basaltic rocks are enriched in n relative to fresh basalts however published data from dsdp odp hole 504b a reference site for the composition of the oceanic crust suggest that seawater alteration leads to the n depletion of the upper ocean crust to better address this issue we analyzed n concentration and isotope composition of 21 altered basalts from the lavas and sheeted dikes sampled by hole 504b these new analyses show significant n enrichment up to 14 1 ppm relative to fresh degassed morb 1 ppm the differences observed between earlier and modern data are interpreted as resulting from analytical artifact due to the earlier use of a molybdenum crucible for n extraction furthermore our new data show a progressive decrease of n concentration with depth from 14 1 to 1 4 ppm nitrogen isotope compositions display a large range with 15 n values from 0 9 to 7 3 and most likely reflect multiple stages of alteration with fluids of various compositions in contrast to n concentration 15 n values do not show a global depth trend but oscillate around a mean value of 3 0 2 2 1sd the n concentration shows a positive correlation with bulk rock 18 o values suggesting that n behavior during alteration process is mainly controlled by temperature we propose that n speciation in the hydrothermal fluid is dominated by nh3 nh4 at low temperature 200 c these new data are used to re evaluate the global flux of n input into central american subduction zone showing that the upper basaltic crust represent about 20 of the total n buried in subduction zone a comparison with previous results obtained on n degassed in volcanic arc illustrates that in warm subduction zone like central america up to 50 of the subducted n may be transferred to the deep mantle this contrasts with cold subduction environments where 80 of the n inputs escape sub arc slab devolatilization and supports that the geothermal gradient plays a major role in determining the n fate in subduction zones

mixing processes within the polar night jet abstract lagrangian material line simulations are performed using u k meteorological office assimilated winds and temperatures to examine mixing processes in the middle and lower stratospheric polar night jet during the 1992 southern hemisphere spring and northern hemisphere winter the lagrangian simulations are undertaken to provide insight into the effects of mixing within the polar night jet on observations of the polar vortex made by instruments onboard the upper atmosphere research satellite during these periods a moderate to strong kinematic barrier to large scale isentropic exchange similar to the barrier identified in gcm simulations is identified during both of these periods characteristic timescales for mixing by large scale isentropic motions within the polar night jet range from 20 days in the southern hemisphere lower stratosphere to years in the northern hemisphere middle stratosphere the long mixing timescales found in the northern hemisphere polar night jet do not persist instead

a preliminary study of 15n14n in octahedral growth form diamonds abstract the 13 c 15 n and nitrogen concentrations have been determined in 43 octahedral diamonds from southern africa australia and north america the sample set included locations such as finsch south africa a mine which produces diamonds having 13c values close to 5 and argyle australia a mine which produces 13c depleted diamonds the nitrogen within high 13c diamonds 13 c 6 4 to 2 9 was generally depleted in 15n relative to atmospheric nitrogen 15n 12 3 to 5 9 mode 4 similar to the results which have been obtained previously from fibrous diamond it is believed that the volatiles from which these diamonds grew are primitive being derived from a source located beneath the continental lithosphere which may have changed little in terms of 13c and 15n since the mid archean the low 13c diamonds 13c 19 4 to 9 5 contained nitrogen generally enriched in 15n relative to air 15n 3 0 to 16 4 mode 5 it is suggested that the major carbon isotope heterogeneity within the mantle as represented by diamonds such as these is located in deep mechanically unstable regions of the continental lithosphere the isotopic compositions of both c and n are consistent with this heterogeneity resulting from the subduction of crustal material however isotope fractionation related directly to diamond growth cannot be ruled out

first continuous gps soundings of temperature structure over antarctic winter from formosat 3 cosmic constellation 1 the formosat 3 cosmic mission provides unprecedented spatial coverage of daily sounding profiles of the antarctic atmosphere our analysis shows that temperature profiles from these global positioning system gps soundings agree well with the radiosondes over the south pole and neumayer stations during the 2006 southern hemisphere sh winter season these gps soundings reveal a vertical domain of low temperature e g t 78 c at 28 km altitude that is not clearly defined by the antarctic radiosondes latitudinal analysis of the gps soundings shows that regions with t 78 c occur from about 10 km to 28 km altitudes indicating an 18 km thick of the cold vertical layer the extremely cold regions are found at latitudes between 71 s and 87 s and in altitudes between 15 and 25 km not coinciding with the geographical south pole these results demonstrate the potential of the formosat 3 cosmic data for polar studies

multiple growth events during diamond genesis an integrated study of carbon and nitrogen isotopes and nitrogen aggregation state in coated stones the internal structure and growth history of diamonds have been investigated by the study of carbon isotopes and the abundance isotope composition and aggregation state of nitrogen polished plates of zoned diamonds coated stones were laser sectioned for infrared mapping and isotope profiling nine small cubic and three small octahedral diamonds from zaire and two coated stones and five small cubic diamonds specifically from the mbuji mayi area of that country were also investigated the isotope composition and infrared characteristics of the diamonds of cubic habit including coats were found to be indistinguishable with 13c in the range 5 9 to 7 5 and all the nitrogen being present as the paired structure iaa with a 15n of between 3 1 and 8 0 the diamonds of octahedral habit including the cores of the coated stones were more variable 13c varied from 4 9 to 9 8 infrared spectra of the octahedral diamond exhibited either strong iaa characteristics or a combination of iaa and iab platelets were present in most cases 15n values from octahedral diamonds varied from 5 8 to 13 4 the data suggest that the octahedral diamonds represent a variety of growth events separated in time and or space and that the diamonds resided in the lithosphere for a period sufficient for thermal maturation in the case of the coated stones the octahedral diamonds were later involved in an event which added a component from a single relatively homogeneous reservoir cubic habit diamonds were formed at the same time this latter event is believed to be related to the kimberlite eruption comparison of the data with carbon isotope analyses of cubic diamond from other sources suggests that this reservoir could be widespread

noble gas state of the ancient mantle as deduced from noble gases in coated diamonds cores and coats of five coated diamonds one from botswana and four from zaire were separately analyzed for their noble gases noble gases in the diamonds are essentially of a trapped origin including radio and nucleogenic components such as4he 40ar 21neexcess and excesses in xe isotopes 129 131 136 the fairly precise elemental and isotopic abundances allow us to infer the noble gas state in the ancient mantle 20ne 22ne ratios are fairly constant 11 8 0 4 and very close to that of sep solar energetic particle ne but distinctly different from the atmospheric ratio 21ne 22ne ratios range from 0 028 to 0 06 which is attributed to nucleogenic 21ne from 18o n 21ne and 24mg n 21ne reactions the difference in 20ne 22ne between atmosphere and mantle can be attributed to the hydrodynamic escape of hydrogen from the primitive atmosphere during the very early stage in the earth s history 38ar 36ar and kr isotopic ratios are identical to the atmospheric values within 1 after correction for 238u or 244pu fission xe the 131 136xe abundance ratios are indistinguishable from atmospheric ratios lighter xe isotopes 124 128xe are also likely to be atmospheric but a final conclusion must wait until better data are obtained in a 136xe 130xe 129xe 130xe diagram diamond data lie on the same line as defined for morb the observed identical correlation for both diamonds and morb s appears to suggest that the progenitor of the excess131 136xe is 244pu but not238u though the direct xe isotopic measurements was not precies enough to decide unanimously the progenitor

southern hemisphere extratropical gravity wave sources and intermittency revealed by a middle atmosphere general circulation model abstractsouthern hemisphere extratropical gravity wave activity is examined using simulations from a free running middle atmosphere general circulation model called kanto that contains no gravity wave parameterizations the total absolute gravity wave momentum flux mf and its intermittency diagnosed by the gini coefficient are examined during january and july the mf and intermittency results calculated from the kanto model agree well with results from satellite limb and superpressure balloon observations the analysis of the kanto model simulations indicates the following results nonorographic gravity waves are generated in kanto in the frontal regions of extratropical depressions and around tropopause level jets regions with lower higher intermittency in the july midstratosphere become more less intermittent by the mesosphere as a result of lower level wave removal the gravity wave intermittency is low and nearly homogeneous throughout the sh middle atmosphere during january this indicates t

growth rate and salinity profile of first year sea ice in the high arctic this paper describes the growth of sea ice and the salinity profiles observed in eclipse sound near pond inlet baffin island canada during the winter of 1977 78 a numerical method of calculation has been developed to incorporate the variations in snow conditions and physical properties of ice and snow during the growth season it is shown that the growth rate can be predicted reasonably well it is also shown that the vertical salinity profile in the ice towards the end of the season provides a record of previous climatological conditions a dependence has been shown between the predicted growth rate and the measured salinity

observations of vertically thick polar stratospheric clouds and record low temperature in the arctic vortex on 12 and 13 january 2001 backscatter sondes launched at sodankyla finland 67 n 27 e detected an extraordinarily thick polar stratospheric cloud layer of more than 8 km vertical extent on these days the polar vortex passed over northern scandinavia this provided synoptic scale low stratospheric temperatures leading to the formation of both liquid and solid phase particles two days later on 15 january 2001 a regular radiosonde measured record low temperature of 176 7 k at an altitude of 25 2 km at the vortex edge high vertical resolution radiosonde profiles and meteorological analyses indicate strong mountain wave activity on this day this provides further evidence that the coldest temperatures in the arctic lower stratosphere occur as a consequence of mountain wave cooling under cold synoptic scale background conditions