gravity wave propagation and dissipation from the stratosphere to the lower thermosphere 1 one night 28 october 2003 temperature and horizontal wind measurements by a resonance sodium na wind temperature lidar at maui 20 7 n 156 3 w and temperature measurement by a rayleigh lidar at mauna loa observatory mlo 19 5 n 155 6 w hawaii were used to study gravity wave gw propagation from the lower stratosphere to the lower thermosphere a dominant wave mode was identified from 35 to 103 km the wave was partially dissipated and propagating upward with a scale height of temperature amplitude at 14 km a damping layer was present around the stratopause where the wave amplitude was small which also corresponded to a low static stability layer the vertical wavelengths were larger in the mesosphere 12 13 km than in the stratosphere 6 7 km consistent with the decreasing static stability with altitude hodograph analysis of the na lidar wind data showed that the wave was propagating northward and the horizontal wavelength was 2140 km and intrinsic period was 15 h in the region 84 103 km the apparent period was 6 h and consistent with doppler shift of the background wind it is suggested that the convective zone over the equator to the south of hawaii provided a constant gw source that is responsible for the observed gw throughout the night

modelling the generation of gravity waves by a maritime continent thunderstorm observed wind and temperature profiles are used to initialize a model calculation of a maritime continent thunderstorm and the numerical solution is used to explore the effect of tropospheric shear on the gravity wave generation the resultant convective system is qualitatively similar to that observed the modelled gravity waves propagate away from the cloud with wave fronts that are approximately circular implying that the convective clouds do not generate waves which propagate in a preferred direction the gravity wave generation is related to the oscillation of the convective updraughts about their level of neutral buoyancy while the general features of the gravity waves are similar in most respects to a previous study which used an idealized wind profile the frequency of the gravity waves is doppler shifted by the tropospheric wind shear the result is a much broader power spectrum in comparison to the idealized cases

global estimates of gravity wave parameters from gps radio occultation temperature data 1 gravity waves gws play critical roles in the global circulation and the temperature and constituent structures in the middle atmosphere they also play significant roles in the dynamics and transport and mixing processes in the upper troposphere and lower stratosphere and can affect tropospheric weather despite significant advances in our understanding of gws and their effects in different regions of the atmosphere in the past few decades observational constraints on gw parameters including momentum flux and propagation direction are still sorely lacking global positioning system gps radio occultation ro technique provides global all weather high vertical resolution temperature profiles in the stratosphere and troposphere the unprecedentedly large number of combined temperature soundings from the constellation observing system for meteorology ionosphere and climate and challenging minisatellite payload gps ro missions allows us to obtain gw perturbations by removing the gravest zonal modes using the wavelet method for each day we extended the gw analysis method of alexander et al 2008 to three dimensions to estimate the complete set of gw parameters including momentum flux and horizontal propagation direction from the gw temperature perturbations thus derived to demonstrate the effectiveness of the analysis we showed global estimates of gw temperature amplitudes vertical and horizontal wavelengths intrinsic frequency and vertical flux of horizontal momentum in the altitude range of 17 5 22 5 km during december 2006 to february 2007 consistent with many previous studies gw temperature amplitudes are a maximum in the tropics and are generally larger over land likely reflecting convection and topography as main gw sources gw vertical wavelengths are a minimum at equator likely due to wave refraction whereas gw horizontal wavelengths are generally longer in the tropics most of the waves captured in the analysis of the gps data are low intrinsic frequency inertia gws and the estimated intrinsic frequencies scaled by the coriolis parameter also show a strong maximum at equator enhanced wave fluxes are linked to convection topography and storm tracks among others as preliminary tests of the analysis in deriving horizontal propagation directions we compared the gps estimates with the corresponding estimates from the u s high vertical resolution radiosonde data using the conventional stokes parameters method and we also conducted a separate analysis of the gps data over the southern andes in south america we also showed the first global estimates of gw propagation directions from the gps data finally the sensitivity of the analysis to the temporal and spatial dimensions of the longitude latitude time cells and the uncertainties of the analysis and possible ways to reduce these uncertainties are discussed

gravity waves generated by a tropical cyclone during the step tropical field program a case study overflights of a tropical cyclone during the australian winter monsoon field experiment of the stratosphere troposphere exchange project step show the presence of two mesoscale phenomena a vertically propagating gravity wave with a horizontal wavelength of about 110 km and a feature with a horizontal scale comparable to that of the cyclone s entire cloud shield wavelength of 250 km or greater the larger feature is fairly steady though its physical interpretation is ambiguous the 110 km gravity wave is transient having maximum amplitude early in the flight and decreasing in amplitude thereafter its scale is comparable to that of 100 to 150 km diameter cells of low satellite brightness temperatures within the overall cyclone cloud shield these cells have lifetimes of 4 5 to 6 hours aircraft flights through the anvil show that these cells correspond to regions of enhanced convection higher cloud altitude and upwardly displaced potential temperature surfaces a three dimensional transient linear gravity wave simulation shows that the temporal and spatial distribution of meteorological variables associated with the 110 km gravity wave can be simulated by a slowly moving transient forcing at the anvil top having an amplitude of 400 600 m a lifetime of 4 5 6 hours and a size comparable to the cells of low brightness temperature the forcing amplitudes indicate that the zonal drag due to breaking mesoscale transient convective gravity waves is definitely important to the westerly phase of the stratopause semiannual oscillation and possibly important to the easterly phase of the quasi biennial oscillation there is strong evidence that some of the mesoscale gravity waves break below 20 km as well the effect of this wave breaking on the diabatic circulation below 20 km may be comparable to that of above cloud diabatic cooling

the origin and spread of grass dominated ecosystems in the late tertiary of north america preliminary results concerning the evolution of hypsodonty abstract sediment samples were collected in northwestern nebraska from the following lithologic units 1 the upper oligocene monroe creek formation the lower miocene harrison formation and upper harrison beds of the arikaree group and 2 the lower miocene runningwater formation and the dawes clay member box butte formation of the ogallala group the samples were processed using heavy liquid extraction and analyzed for siliceous plant microfossils phytoliths all samples yielded well preserved and diverse assemblages dominated by grass phytoliths but included phytoliths produced by woody and herbaceous dicotyledons palms and sedges the abundance of woody dicotyledons and palms decreased up section the grass assemblages consisted mainly of festucoid c3 phytolith morphotypes an index assessing the amount of tree cover d p the ratio of dicotyledon phytoliths to grass phytoliths was employed to interpret the data according to this analysis there was open c3 dominated grassland in the study area between 25 and 17 ma at least 7 ma before supposed adaptations to grasslands in ungulates hypsodonty originate

a study of the dynamics of the equatorial lower stratosphere by use of ultra long duration balloons 2 gravity waves in the late southern winter of 1998 centre national d etudes spatiales cnes the french space agency released six 10 m diameter superpressure balloons from a location near quito ecuador three balloons collapsed soon after launching but the remaining three drifted westward for a few weeks at altitudes between 19 and 20 km two of those balloons crossed the pacific ocean before falling above the maritime continent while the other completed a revolution around the earth and crossed the pacific for a second time before its final fall despite the small number and the relatively short duration of the flights the balloons provided a unique in situ data set for the lower equatorial stratosphere this part 1 of a two part paper describes this data set and analyzes outstanding features in the planetary scales part 2 focuses on gravity wave scale it is argued that balloon trajectories over the pacific are primarily determined by the westward drift during the easterly phase of the equatorial quasi biennial oscillation qbo and the meridional velocity field of a mixed rossby gravity yanai wave with an apparent period of 4 days and zonal wave number 4 this wave appears to have two episodes of amplification during the balloon flights it is also argued that the balloons show evidence of oscillations with periods between 2 and 4 days and of a kelvin wave with an apparent period close to 10 days and zonal wave number 1 in this way the balloon behavior provided a pictorial view of air parcel trajectory in the equatorial lower stratosphere it is stated that larger balloon campaigns can provide excellent in situ data sets for studies on the dynamics and composition of the middle atmosphere

large potential energy of gravity waves over a smooth surface with little convection simulation and observation 1 a numerical experiment is conducted using an atmospheric general circulation model agcm to investigate the presence of the large potential energy over a region of low topography and little convective activity focusing on the tropical atlantic region 10 e to 20 w 0 to 20 s it is found that gravity waves with a time period of 24 hours are excited near the equator 5 15 n in a region of large moist heating extending vertically up to 10 13 km the gravity waves propagate upward from this region with a bias toward the south and are manifested as large energy fluxes in the cross equatorial region enhanced energy fluxes are therefore simulated at 20 30 km altitude over a region with no significant source of gravity waves and are confirmed using global positioning satellite meteorology gps met experiment data

sequence stratigraphy of carbonate evaporite basins models and application to the upper permian zechstein of northeast england and adjoining north sea the successions of carbonate evaporite basins which are periodically cut off from the world ocean are considered in terms of their sequence stratigraphy two basin types are distinguished those where incomplete drawdown takes place and those showing complete drawdown and wholesale basin desiccation it is argued that following relative sea level falls sequences begin with the evaporites precipitated as marginal lowstand gypsum wedges in the first basin type and as lowstand basin centre halite fills in the second the evaporites pass up into carbonate sediments which are mainly deposited on shallow water platforms around the basin during transgressive and highstand systems tracts the concepts and models developed are applied to the zechstein upper permian strata of northeast england and adjoining north sea seven sequences are proposed with some containing thin parasequences the sequence approach to carbonate evaporite basins which considers both basin margin and basin centre facies gives a more encompassing perspective of sedimentation than the traditional cycle concept with its emphasis on the basin centre

sulfate oxygen 17 anomaly in an oligocene ash bed in mid north america was it the dry fogs 1 the oxygen and sulfur isotope compositions of sulfate particularly the oxygen 17 anomaly provide clues to the origin of sulfate we report a variable oxygen 17 anomaly for water and acid leached sulfate from an oligocene volcanic ash bed in the northern high plains u s a we find no sulfate o 17 anomaly however in freshly collected ashes from recent eruptions around the world the oligocene paleoclimatic and sedimentary evidence argues against a hyperarid condition in the high plains thus a long term background atmospheric sulfate accumulation is less likely the origin combining sulfur isotope data we suggest that the anomalous sulfate was associated with volcanic eruptions in the west but was not directly carried by ash falls extreme dry fog sulfate haze events resulting from tropospheric oxidation of volcanic sulfur gases might provide a viable explanation for the sulfates in the ash bed that carry the oxygen 17 anomaly

a numerical study of gravity waves induced by convection associated with typhoon rusa 1 typhoon rusa 2002 is simulated using a three dimensional mesoscale model mm5 and the characteristics of gravity waves generated by convection associated with the typhoon are investigated the gravity waves in the stratosphere propagate in two directions northwestward and southeastward according to the convective bands propagating in the same directions although the typhoon itself moves north northeastward spectral analyses show that the inertio gravity waves igws in the stratosphere generated by rusa have a dominant horizontal wavelength of 300 600 km a vertical wavelength of 3 11 km and a period of 6 11 hrs a large fraction of the igws is filtered out in the upper troposphere and stratosphere mainly due to the critical level filtering process the decreased magnitude of the momentum flux with height in a non filtered region is likely due to the damping process with a minor contribution by the wave breaking process that can occur exclusively near the critical level phase speeds

wavelet analysis of stratospheric gravity wave packets over macquarie island 1 wave parameters we describe a technique to detect gravity wave packets in high resolution radiosonde soundings of horizontal wind and temperature the vertical profiles of meridional and zonal wind speeds are transformed using the morlet wavelet and regions of high wind variance in height wavenumber space are identified as gravity wave packets application of the stokes parameter analysis to horizontal wind and temperature profiles of the reconstructed wave packets yields the wave parameters the technique was applied to twice daily radiosonde launches at macquarie island 55 s 159 e between 1993 and 1995 a strong seasonal cycle in the total wave variance was found with a maximum in winter the amount of wave energy propagating downward from the upper stratosphere also maximized in winter waves propagated predominately toward the southwest in winter but in summer propagation directions were approximately isotropic the intrinsic frequencies were close to the inertial frequency and the waves had inferred horizontal wavelengths of several hundred kilometers

characteristics of high frequency gravity waves generated by tropical deep convection case studies 1 high frequency gravity waves generated by tropical deep convection play a major role in shaping the general circulation of the middle atmosphere special experiments were conducted to capture two convective events on 16 may and 5 june 2006 using vhf radar located at gadanki 13 5 n 79 2 e a tropical indian station control day observations were also made for necessary comparisons background wind and temperature information was obtained by gps radiosonde flights launched from the same site this work has utilized these valuable data sets to delineate characteristics of convectively generated gravity waves a superposition of gravity waves is observed with different scales after the deep convective events vertical wave number spectra of radial velocities show steeper slopes and higher power spectral densities during convection which slowly reduce to their normal values the present case studies suggest the mechanical oscillator mechanism to be a major source of convective gravity wave generation in the tropics estimates of vertical wind variances and momentum fluxes of short period 2 h wind fluctuations show large enhancements on convective days in comparison to control days the momentum flux frequency spectra revealed a higher contribution of 30 65 min wave periods to the mean profile in the lower stratosphere the wavelet transform momentum flux spectra displayed the temporal variability and discretization of the gravity wave momentum fluxes in frequency and time

a threshold in soil formation at earth s arid hyperarid transition the soils of the atacama desert in northern chile have long been known to contain large quantities of unusual salts yet the processes that form these soils are not yet fully understood we examined the morphology and geochemistry of soils on post miocene fans and stream terraces along a south to north 27 to 24 s rainfall transect that spans the arid to hyperarid transition 21 to 2 mm rain y 1 landform ages are 2 my based on cosmogenic radionuclide concentrations in surface boulders and ar isotopes in interbedded volcanic ash deposits near the driest site indicate a maximum age of 2 1 my a chemical mass balance analysis that explicitly accounts for atmospheric additions was used to quantify net changes in mass and volume as a function of rainfall in the arid 21 mm rain y 1 soil total mass loss to weathering of silicate alluvium and dust 1030 kg m 2 is offset by net addition of salts 170 kg m 2 the most hyperarid soil has accumulated 830 kg m 2 of atmospheric salts including 260 kg sulfate m 2 and 90 kg chloride m 2 resulting in unusually high volumetric expansion 120 for a soil of this age the composition of both airborne particles and atmospheric deposition in passive traps indicates that the geochemistry of the driest soil reflects accumulated atmospheric influxes coupled with limited in soil chemical transformation and loss long term rates of atmospheric solute addition were derived from the ion inventories in the driest soil divided by the landform age and compared to measured contemporary rates with decreasing rainfall the soil salt inventories increase and the retained salts are both more soluble and present at shallower depths all soils generally exhibit vertical variation in their chemistry suggesting slow and stochastic downward water movement and greater climate variability over the past 2 my than is reflected in recent 100 y rainfall averages the geochemistry of these soils shows that the transition from arid to hyperarid rainfall levels marks a fundamental geochemical threshold in wetter soils the rate and character of chemical weathering results in net mass loss and associated volumetric collapse after 105 to 106 years while continuous accumulation of atmospheric solutes in hyperarid soils over similar timescales results in dramatic volumetric expansion the specific geochemistry of hyperarid soils is a function of atmospheric sources and is expected to vary accordingly at other hyperarid sites this work identifies key processes in hyperarid soil formation that are likely to be independent of location and suggests that analogous processes may occur on mars

quantifying sulfate components and their variations in soils of the mcmurdo dry valleys antarctica 1 many soils of the mcmurdo dry valleys mdv antarctica being old hyperarid and frigid have accumulated abundant atmospheric salts over the last several million years this salt repository offers an opportunity to study atmospheric chemistry past and present the origin and transport of ions in soils the weathering activity of soils and postdepositional soil leaching processes within this unique environment in particular soil sulfate in the mdv is known to have multiple origins but the precise proportions of different sulfate components remain elusive here we test a hypothesis that soil sulfate in the mdv is a predictable mixture of three major components sea salt sulfate non sea salt sulfate and background sulfate derived from weathering and volcanic sources that to a large extent varies as a function of elevation and distance from the coast by measuring sulfate s three stable isotope parameters i e 17o 18o and 34s plus estimating independently the end member stable isotope parameters for the three components on the basis of published reports and our measured data we solve explicitly the mixing proportion for each component using a set of three simultaneous linear equations the results from four spatially representative soil profiles show that the sum of such calculated proportions for the three components is very close to unity in most samples suggesting that a simple three component mixing model is a good representation of the soil sulfate budget while significant uncertainties still exist in the isotope compositions of different sulfate end members these data provide important initial constraints on sulfate diversity as well as its spatial and vertical distribution in the mdv

momentum flux estimates accompanying multiscale gravity waves over mount cook new zealand on 13 july 2014 during the deepwave campaign observations performed with a rayleigh lidar and an advanced mesosphere temperature mapper aboard the national science foundation national center for atmospheric research gulfstream v research aircraft on 13 july 2014 during the deep propagating gravity wave experiment deepwave measurement program revealed a large amplitude multiscale gravity wave gw environment extending from 20 to 90 km on flight tracks over mount cook new zealand data from four successive flight tracks are employed here to assess the characteristics and variability of the larger and smaller scale gws including their spatial scales amplitudes phase speeds and momentum fluxes on each flight a large scale mountain wave mw having a horizontal wavelength 200 300 km was observed smaller scale gws over the island appeared to correlate within the warmer phase of this large scale mw this analysis reveals that momentum fluxes accompanying small scale mws and propagating gws significantly exceed those of the large scale mw and the mean values typical for these altitudes with maxima for the various small scale events in the range 20 105 m2 s 2

the origin of gypsum in vertisols in new caledonia determined by isotopic characteristics of sulphur abstract gypsum crystals occur in vertisols on the west coast of new caledonia these soils are derived from the weathering of basic rocks that contain no gypsum the sulphur isotopic ratio 34 s 32 s was used as tracer to identify the origin of the gypsum a total of 26 measurements of 34 s were made on gypsum crystals from the vertisols and compared to those of continental sulphates and to marine gypsum in tidal flats the 34 s value of the crystals located in new caledonian vertisols decreases with increasing distance from the coast this suggests that the gypsum in the vertisols comes from two sources an oceanic source where the major part of the sulphur is introduced by atmospheric precipitation and a continental source where sulphides disseminated in various subsurface deposits are oxidized gypsum from atmospheric precipitation penetrates the vertisols through vertical cracks that probably formed in dry seasons during the last glacial period

sulfate oxygen 17 anomalies in desert varnishes rock varnishes are ubiquitous in arid regions on earth and are believed to be commonly present on mars here we report high water soluble sulfate and nitrate contents in desert varnishes from the death valley region of southwestern u s a and that sulfate in varnishes possess 17o 18o ratios that do not fall on terrestrial mass dependent fractionation line sulfate from wet and dry atmospheric deposition is probably the source of the 17o anomalies the anomalies are only moderately lower than that of aerosol sulfates collected from the greater los angeles area indicating probably more than half of the sulfate in desert varnish is supplied by atmospheric deposition this finding suggests that earth surface environments are constantly accumulating 17o anomalous sulfate from the atmosphere arid and stable conditions facilitate the preservation of these atmospheric signatures this finding also indicates that different 17o 18o ratios found in different components in the martian meteorites may result from atmospheric chemical processes

gravity waves generated by deep tropical convection estimates from balloon observations and mesoscale simulations 1 convective gravity waves in the tropics are studied by analyzing in situ measurements from long duration stratospheric balloons launched during the preconcordiasi campaign 2010 and mesoscale simulations an improved temporal resolution of the observations as well as the balloon quasi lagrangian behavior allow an unprecedented investigation of the whole gravity wave spectrum first a case study of gravity waves generated by a developing cyclone tropical storm gelane february 2010 is carried out using observations complemented by numerical simulations with the weather research and forecast model with a resolution down to 1 km distributions of momentum fluxes obtained from both data show reasonable agreement and emphasize waves with short wavelengths 15 km and short periods 20 min still some differences are also found which can likely be related to errors of the modeled background flow second observations from the whole preconcordiasi flights are analyzed with an emphasis on gravity wave momentum fluxes their phase speed distribution has a robust shape with maximum fluxes with near zero ground based phase speeds yet significant momentum fluxes are also found for larger values yielding a mean phase speed of about 27 ms 1 the momentum fluxes are concentrated in short episodes with intense values and their intermittency is quantified using probability distribution functions and the gini coefficient 0 5 0 6 the relative importance of convective and topographic sources are investigated suggesting comparable intensities but a greater occurrence frequency of convective events waves emitted by tropical storm gelane do not stand out relative to other convective events

mesoscale gravity waves in the mei yu front system abstracthigh resolution cloud permitting simulations with the weather research and forecasting wrf model are performed to study the generation structure and characteristics of mesoscale gravity waves in an idealized mei yu front system two classes of waves are generated successively during the control simulation the first class of waves which is typical of vertically propagating waves excited by the front itself appears as the front develops before the generation of the prefrontal moist convection and has a coherent fanlike pattern from the troposphere to the lower stratosphere the second class of waves which is much stronger than the fanlike waves appears accompanied by the generation of the moist convection it is nearly vertically trapped in the troposphere while it propagates vertically upstream and downstream in the lower stratosphere the source function analysis is introduced to demonstrate that the mechanical oscillator mechanism plays a dominant role in the generation of convective gr

numerical modeling of gravity wave generation by deep tropical convection although convective clouds are known to generate internal gravity waves the mechanisms responsible are not well understood the present study seeks to clarify the dynamics of wave generation using a high resolution numerical model of deep convection over the tiwi islands australia the numerical calculations presented explicitly resolve both the mesoscale convective cloud cluster and the gravity waves generated as the convective clouds evolve they excite gravity waves which are prominent features of the model solutions in both the troposphere and stratosphere the source location is variable in time and space but is related to the development of individual convective cells the largest amplitude gravity waves are generated when the cloud tops reach the upper troposphere a new analysis technique is introduced in which the nonlinear terms in the governing equations are taken as the forcing for linear gravity waves the analysis shows that in the present calculation neither the shear nor the diabatic heating are the dominant forcing terms instead the wave source is most easily understood when viewed in a frame of reference moving with the wind at the level of neutral buoyancy whereupon the source may be described as a vertically oriented oscillating convective updraft this description is consistent with the properties of the modeled stratospheric waves

first observations of intraseasonal oscillations in the equatorial mesosphere and lower thermosphere we present the first evidence of strong intraseasonal 10 100 day variability of the equatorial mesosphere and lower thermosphere drawn from spectral analysis of three years of radar wind measurements of the region at christmas island 2 n 157 w oscillations in the zonal wind as large as 20 m s 1 are observed with periods 60 days at 85 95 km amplitudes attenuate near 80 km then reintensify near 75 km where they are usually of longer period and are out of phase with the upper level oscillations oscillations with periods 35 40 days are also observed at 85 95 km these oscillations are transient and usually appear when the background flow is westward similar signals are not observed in the meridional winds these facts suggest that they could be kelvin waves similar to intraseasonal variability in the equatorial lower atmosphere associated with the madden julian oscillation somewhat different time height activity at 20 days could be related to the 1 3 rossby normal mode or the 20 25 day tropospheric oscillation as it is unlikely that any of these oscillations could propagate to these heights from the lower atmosphere we postulate that they arise due to variations in gravity wave activity and transmissivity induced by intraseasonal oscillations lower down which is transferred into the mean flow when these gravity waves dissipate in the mesosphere this may mean that this intraseasonal activity is a time varying mean wind rather than a forced planetary wave

deformation structures and an alteration zone linked to deposition of volcanogenic sulphate in an ancient playa oligocene of nebraska usa historic sulphur rich volcanic eruptions have altered global climate for as much as five years and much larger events are known from the geologic record at scotts bluff nebraska early oligocene strata of the lower arikaree group contain a tephra bed with abundant calcite pseudomorphs after gypsum previous work has shown sulphate from the pseudomorphs in this tephra bears a high 17 o anomaly indicative of oxidation of sulphur gases by ozone or hydrogen peroxide in the atmosphere possible sources of the tephra were caldera eruptions at about 28 ma in the san juan volcanic field of southwestern colorado 500 km sw of the study site and the eastern great basin 1000 km wsw the present sedimentological study shows that tephra and volcanogenic sulphate were deposited and preserved within a small surfacedischarging playa that developed on the irregular upper surface of aeolian siltstones of the subjacent white river group sulphate solutions including perhaps sulphuric acid percolated downward within the vadose zone dissolving early formed smectite cement within underlying volcaniclastic sandstones reddening these rocks along an irregular alteration front preserved fine scale stratification within the sandstones precludes the possibility that reddening took place during pedogenesis displacive growth of gypsum at the playa centre folded tephra beds and forced tephra into underlying sandstones forming elongate cones the large mass fraction of gypsum now replaced by calcite in the playa sediments suggests a huge long distance delivery of sulphate aerosols some of the sulphate and tephra may have come from the same eruption or the fine grained tephra may simply have aided preservation of dry fog sulphate derived from an unrelated effusive eruption of lava

anomalous 17o compositions in massive sulphate deposits on the earth the variation of 18o that results from nearly all physical biological and chemical processes on the earth is approximately twice as large as the variation of 17o this so called mass dependent fractionation is well documented in terrestrial minerals1 2 evidence for mass independent fractionation 17o 17o 0 52 18o where deviation from this tight relationship occurs has so far been found only in meteoritic material and a few terrestrial atmospheric substances3 in the rock record it is thought that oxygen isotopes have followed a mass dependent relationship for at least the past 3 7 billion years ref 4 and no exception to this has been encountered for terrestrial solids5 here however we report oxygen isotope values of two massive sulphate mineral deposits which formed in surface environments on the earth but show large isotopic anomalies 17o up to 4 6 these massive sulphate deposits are gypcretes from the central namib desert and the sulphate bearing miocene volcanic ash beds in north america the source of this isotope anomaly might be related to sulphur oxidation reactions in the atmosphere and therefore enable tracing of such oxidation these findings also support the possibility of a chemical origin of variable isotope anomalies on other planets such as mars6

rock acoustics and rock mechanics their link in petroleum engineering seismic data represent the most important source of information about underground formations that have not been accessed by excavations or drilling when target formations can be reached by drilling more accurate velocity data are available via logging the primary use of the seismic information is still to map structure however there is a growing interest in using seismic data to derive intrinsic information about rock properties such as porosity clay content etc porosity estimation has traditionally also been the main application of sonic logs in fact an established school of thought holds that velocities in sedimentary rocks are primarily a measure of porosity the lower the velocity the higher the porosity

a late amazonian alteration layer related to local volcanism on mars hydrated minerals on mars are most commonly found in ancient terrains dating to the first billion years of the planet s evolution here we discuss the identification of a hydrated light toned rock unit present in one chasma of the noctis labyrinthus region stratigraphy and topography show that this alteration layer is part of a thin unit that drapes pre existing bedrock crism spectral data show that the unit contains hydrated minerals indicative of aqueous alteration potential minerals include sulfates such as bassanite caso4 1 2h2o or possibly hydrated chloride salts the proximity of a smooth volcanic plain and the similar crater model age late amazonian 100 myr of this plain and the draping deposits suggest that the alteration layer may be formed by the interaction of water with ash layers deposited during this geologically recent volcanic activity the alteration phases may have formed due to the presence of snow in contact with hot ash or eventually solid gas interactions due to the volcanic activity the relatively young age of the volcanic plain implies that recent alteration processes have occurred on mars in relation with volcanic activity but such local processes do not require conditions different than the current climate

stress dependent wave velocities in sedimentary rock cores why and why not abstract rocks exhibit stress dependent wave velocities when their constitutive behaviour shows nonlinear elasticity the main physical mechanism responsible for stress dependency is opening or closure of cracks which is particularly important in brittle rocks crack formation is also associated with breaking of grain contacts we observe by using synthetic sandstones formed under stress a strong stress dependence during unloading simulated coring the reloaded material also shows a strong stress dependency in particular at stress levels below the virgin stress state but also above thus stress dependency as seen in cores taken from great depth is mainly a result of core damage stress independency is associated with linear elasticity such as in well cemented rocks or near the virgin stress conditions as observed here with synthetic sandstones but also occurs in ductile materials where there is a strong component of plasticity we demonstrate stress independence in synthetic sandstone at stress close to the virgin stress state in the elastic regime but also well above in the non elastic deformation regime high porosity high clay content shale was found to rather stress insensitive this is thought to be a result of the ductility of the rock caused mainly by the strong affinity of water to clay mineral surfaces

large amplitude mountain waves in the mesosphere accompanying weak cross mountain flow during deepwave research flight rf22 mountain wave mw propagation and dynamics extending into the upper mesosphere accompanying weak forcing are examined using in situ and remote sensing measurements aboard the national science foundation national center for atmospheric research gulfstream v gv research aircraft and the german aerospace center falcon the measurements were obtained during falcon flights ff9 and ff10 and gv research flight rf22 of the deep propagating gravity wave experiment deepwave performed over mount cook new zealand on 12 and 13 july 2014 in situ measurements revealed both trapped lee waves having zonal wavelengths of x 12 km and less and larger scale vertically propagating mws primarily at x 20 60 km and 100 300 km extending from west to 400 km east of mount cook gv rayleigh lidar measurements from 25 to 60 km altitudes showed that the weak forcing and zonal winds that increased from 12 m s at 12 km to 40 and 130 m s at 30 and 55 km respectively enabled largely linear mw propagation and strong amplitude growth with altitude into the mesosphere

sulfate in modern playa settings and in ash beds in hyperarid deserts implication for the origin of 17o anomalous sulfate in an oligocene ash bed abstract a large amount of calcite pseudomorphs after gypsum were discovered in a volcanic ash bed and its underlying sand siltstone in the gering formation late oligocene northwestern ne usa the highly positive 17o anomalies in the residual sulfate indicate that the sulfate could only have come from the oxidation of sulfur gases by ozone in the atmosphere we previously proposed that it was most likely the result of an extreme tropospheric sulfate haze dry fog event that was associated with volcanic eruptions in the west to test the dry fog hypothesis we examine here two alternative scenarios that also involve atmospheric sulfate deposition but do not imply a dramatic volcanic and dry fog source 1 is it possible that some playas in arid or semiarid regions accumulate the type of atmospheric sulfate deposits as we see in the mid gering bed by the inflow of surface water or groundwater 2 could a period of hyperaridity and stability during the late oligocene have caused a significant accumulation of atmospheric background sulfate onto the mid gering ash bed surface sulfates from a variety of playa settings were collected and measured for their 17o anomalies the sulfate isotope both o and s and concentration profiles of two volcanic ash beds that are currently exposed in the central atacama desert chile and in taylor valley of the antarctica dry valleys were studied along with their sedimentary features these two ash beds were chosen for comparison because of their significant levels of atmospheric sulfate accumulated during prolonged and hyperarid climatic conditions results showed no or minimal 17o anomalies in any of the playa sulfate samples from around the world and none of the parameters in the mid gering ash profile matches those in either of the two volcanic ash profiles in modern hyperarid settings conclusion the observed 17o anomalous gypsum deposit in the mid gering ash bed is most likely the result of a series of extreme dry fogs that resulted in an intense pulse of atmospheric sulfate deposition to a semiarid playa setting

extremely acid permian lakes and ground waters in north america evaporites hosted by red beds red shales and sandstones some 275 265 million years old extend over a large area of the north american mid continent1 they were deposited in non marine saline lakes pans and mud flats2 settings that are typically assumed to have been alkaline here we use laser raman microprobe analyses of fluid inclusions trapped in halites from these permian deposits to argue for the existence of highly acidic ph 1 lakes and ground waters these extremely acidic systems may have extended over an area of 200 000 km2 modern analogues of such systems may be natural acid lake and groundwater systems ph 2 4 in southern australia3 4 5 6 7 8 9 both the ancient and modern acid systems are characterized by closed drainage arid climate low acid neutralizing capacity and the oxidation of minerals such as pyrite to generate acidity the discovery of widespread ancient acid lake and groundwater systems demands a re evaluation of reconstructions of surface conditions of the past and further investigations of the geochemistry and ecology of acid systems in general

using strontium isotopes to determine the age and origin of gypsum and anhydrite beds the variation of 87sr 86sr in seawater with time can be used to determine the age of calcium sulfate beds precipitated from brine derived from seawater the determination of a marine origin can be established by the consistency of strontium isotope results from samples at different stratigraphic levels in a single gypsum anhydrite bed collected at separated sites the scatter of strontium isotope results in the gypsum anhydrite samples examined here is interpreted to result from the contribution of meteoric strontium to the salina strontium isotope results from three evaporite settings the jurassic todilto formation from new mexico the permian blaine formation from blaine county oklahoma and the permian salado formation from new mexico are used to determine the age and origin of the parent brine for these gypsum anhydrite beds the calcium sulfate beds from each of these formations precipitated from salinas that originated with a marine flooding but show at different times and localities volume do

a transient method of measuring the thermal properties of rocks the aim of the paper is to describe a new rapid transient method for the determination of thermal diffusivity and thermal conductivity of rocks the present transient method is based on the application of a constant heat flux to the top surface of a block of rock that is insulated on all other surfaces results of a sensitivity analysis of the method indicate that thermal diffusivity can be measured to a best accuracy of about 3 percent and thermal conductivity of saturated rocks can be determined to a best accuracy of about 8 percent the method provides estimates of thermal conductivity that are consistent with estimates made using the steady state divided bar apparatus the method is applied to determine the thermal conductivity of a suite of rocks from western australian sedimentary basins

gravity wave activity associated with tropical convection detected in toga coare sounding data upper air sounding data collected at santa cruz 10 s 165 e in the western tropical pacific ocean during november 1992 february 1993 have been used to estimate the gravity wave activity in the upper troposphere and lower stratosphere large amplitude gravity waves with vertical wavelengths of 2 5 km were found in almost all the soundings time series describing the wave activity in two height ranges 10 17 km the upper troposphere and 17 24 km the lower stratosphere are presented and compared to simple measures of the convective cloud activity there is enhanced gravity wave activity associated with increased convection on intraseasonal timescales

seasonal evolution of rossby and gravity wave induced laminae in ozonesonde data obtained from wallops island virginia a method for evaluating the seasonal evolution of ozone laminae using ozonesonde data is discussed the method uses the correlation between small scale ozone and potential temperature variations to distinguish between laminae generated by quasi isentropic filamentation by rossby waves and by vertical displacements of material surfaces by gravity waves data from wallops island virginia show that rossby wave induced ozone laminae are most frequently encountered at wallops during the winter months near 15 km while statistically significant gravity wave induced laminae occur above 15 km during the early winter and at the tropopause from late winter through early spring

numerical simulations of interactions between gravity waves and deep moist convection abstract this study uses a numerical model to simulate deep convection both in the tropics over the ocean and the midlatitudes over land the vertical grid that was used extends into the stratosphere allowing for the simultaneous examination of the convection and the vertically propagating gravity waves that it generates a large number of trajectories are used to evaluate the behavior of tracers in the troposphere and it is found that the tracers can be segregated into different types based upon their position in a diagram of normalized vertical velocity versus displacement conditional sampling is also used to identify updrafts in the troposphere and calculate their contribution to the kinetic energy budget of the troposphere in addition fourier analysis is used to characterize the waves in the stratosphere it was found that the waves simulated in this study have similarities to those observed and simulated by other researchers finally this study examines the wave energy flux as a means to provid

non biological fractionation of stable ca isotopes in soils of the atacama desert chile abstract we measured ca stable isotope ratios 44 40 ca in an ancient 2 my hyperarid soil where the primary source of mobile ca is atmospheric deposition most of the ca in the upper meter of this soil 3 5 kmol m 2 is present as sulfates 2 5 kmol m 2 and to a lesser extent carbonates 0 4 kmol m 2 in aqueous extracts of variably hydrated calcium sulfate minerals 44 40 ca e values vs bulk earth increase with depth 1 4 m from a minimum of 1 91 to a maximum of 0 59 the trend in carbonate 44 40 ca in the top six horizons resembles that of sulfate 44 40 ca but with values 0 1 0 6 higher the range of observed ca isotope values in this soil is about half that of 44 40 ca values observed on earth linear correlation among 44 40 ca 34 s and 18 o values indicates either a a simultaneous change in atmospheric input values for all three elements over time or b isotopic fractionation of all three elements during downward transport we present evidence that the latter is the primary cause of the isotopic variation that we observe sulfate 34 s values are positively correlated with sulfate 18 o values r 2 0 78 and negatively correlated with sulfate 44 40 ca e values r 2 0 70 if constant fractionation and conservation of mass with downward transport are assumed these relationships indicate a 44 40 ca fractionation factor of 0 4 in caso 4 the overall depth trend in ca isotopes is reproduced by a model of isotopic fractionation during downward ca transport that considers small and infrequent but regularly recurring rainfall events near surface low ca isotope values are reproduced by a rayleigh model derived from measured ca concentrations and the ca fractionation factor predicted by the relationship with s isotopes this indicates that the primary mechanism of stable isotope fractionation in caso 4 is incremental and effectively irreversible removal of an isotopically enriched dissolved phase by downward transport during small rainfall events

caliche as a geological repository for atmospheric sulfate 1 recent studies demonstrate that important information on sulfur source oxidation pathway transport pattern and reaction kinetics of atmospheric oxidation of sulfur gases can be uncovered by measuring multiple isotope compositions of the oxidation product secondary atmospheric sulfate sas sas from earth s distant past however is rarely preserved in the rock records because of its high solubility and small quantity we report here from the measurement of 47 modern and fossil caliche samples that caliches contain variable amounts of carbonate associated sulfate cas and the 17o values of the cas range from 0 12 to 2 32 with most values higher than the background value of 0 05 for seawater sulfate indicating the presence of an sas component derived from the oxidation of sulfur gases by atmospheric ozone or related oxidants this study demonstrates that caliche a pedogenic carbonate common in the geologic record could serve as a repository for ancient sas

the gravity wave response above deep convection in a squall line simulation abstract high frequency gravity waves generated by convective storms likely play an important role in the general circulation of the middle atmosphere yet little is known about waves from this source this work utilizes a fully compressible nonlinear numerical two dimensional simulation of a midlatitude squall line to study vertically propagating waves generated by deep convection the model includes a deep stratosphere layer with high enough resolution to characterize the wave motions at these altitudes a spectral analysis of the stratospheric waves provides an understanding of the necessary characteristics of the spectrum for future studies of their effects on the middle atmosphere in realistic mean wind scenarios the wave spectrum also displays specific characteristics that point to low physical mechanisms within the storm responsible for their forcing understanding these forcing mechanisms and the properties of the storm and atmosphere that control them are crucial first steps toward developing

small scale gravity waves in the upper mesosphere and lower thermosphere generated by deep tropical convection a time dependent nonlinear fully compressible axisymmetric plane numerical model is used to simulate the generation of small scale gravity waves in the upper mesosphere and lower thermosphere by intense deep convection in the troposphere the simulations show that major convective storms in the tropics excite a broad spectrum of upper mesosphere lower thermosphere gravity waves above the storm centers the wave field includes a component that is guided in a thermal duct in the lower thermosphere and propagates horizontally outward from above the storm storms excite oscillations over the source which are initially confined to a stratospheric duct but leak into the thermospheric duct over time generating a long train of small scale ducted waves this ringing phenomenon persists for several hours after the storm has ended the ducted disturbances may propagate large distances from the source and explain observations of a strong summertime anisotropy favoring southward propagation of small scale waves observed in the airglow over adelaide more than 2000 km to the south of the storm events

petrophysical laboratory measurements for basin and reservoir evaluation the quality of computer modelling in basin and reservoir studies critically depends on the quality of input data core measurements may directly provide such data cores also help establish correlations between log measured parameters and parameters required in basin or reservoir evaluation correlations may also permit simple index measurements to be used for data assessment instead of more tedious laboratory procedures this paper summarizes different petrophysical laboratory techniques that can be utilized for these purposes the importance of performing laboratory measurements under representative conditions and to account for core damage effects is underlined

physical properties of shale at temperature and pressure deformational properties p wave and s wave velocities and electrical resistivity were measured for three north sea malm shales in the laboratory under pressures to 800 bars and temperatures to 100 c these data were used to evaluate how factors such as mineralogy microstructure compaction and pore fluid conductivity affect a shale s seismic and electrical responses deformation in the shales is dominated by inelastic processes which cause time dependent changes in velocity resistivity and pore pressure overall shales are less sensitive to pressure changes as compared to sandstones of similar porosity however changes in temperature result in large changes in physical properties as compared to sandstones or shaly sands p wave and s wave velocities may decrease by as much as 10 percent over the temperature range studied and calculated activation energies for surface conduction are nearly twice those observed in shaly sands these comparisons emphasize fundamental differences in fabric among the

quantification of gravity wave forcing in driving the stratospheric quasi biennial oscillation 1 using long term rayleigh lidar temperature observations during april 1998 april 2005 in the lower stratospheric region momentum flux divergence of the gravity waves of periods 0 5 1 and 2 4 hours are estimated over gadanki 13 5 n 79 2 e india monthly mean zonal winds from ncep ncar reanalysis data over gadanki at two pressure levels 10 and 20 hpa are used to study the characteristics of the quasi biennial oscillation qbo and its month to month acceleration this observed mean flow acceleration is compared with that estimated from the momentum flux divergence of gravity waves which led to a better insight into the role of gravity waves in driving the qbo the present analysis reveals that the contribution of gravity waves towards the westerly phase of qbo varies from 10 60 while that during easterly phase from 10 30 the present study thus quantifies the role of gravity waves in driving the easterly and westerly phases of qbo

determination of matrix thermal conductivity from dry drill cuttings this paper reports experimental data relating the observed dry bulk thermal conductivities of powdered minerals to the porosities of the powdered aggregates the mineral samples were obtained by crushing quartz calcite and feldspar crystals experiments also were conducted on clays from various sources the experimental data suggest an exponential relationship between the dry bulk thermal conductivity and the aggregate porosity the thermal conductivities of the original quartz calcite and feldspar crystals were determined in a dry state to estimate their matrix thermal conductivities an empirical relationship was determined among dry bulk thermal conductivity aggregate porosity and matrix thermal conductivity this empirical relationship provided estimates of matrix thermal conductivity that were consistent with theoretical mix formulae for 50 50 mixtures of combinations of the minerals quartz calcite and feldspar and also a sample of flag sandstone from the north west shelf australia the method was used to estimate heat flows at the sites of two australian north west shelf wells dampier 1 and tryal rocks 1 which are 47 4 mw m2 and 79 7 mw m2 respectively these values are less than sea floor estimates of heat flow in the same region and suggest nonconductive heat transfer processes within the north west shelf sedimentary section

different sulfate sources and their post depositional migration in atacama soils abstract sulfate is one of the major salts accumulated in the hyperarid atacama desert chile its origin has been attributed to local weathering volcanic source sea salt and atmosphere deposition previous studies concluded that atmospheric sulfate is present in the desert but this term was poorly defined in terms of chemical origin and its contribution to the total sulfate budget in soil is debated the contribution of each potential sulfate source is expected to vary geographically due to different source locations efforts to quantify the contribution from each source have been hampered by the lack of well defined isotopic compositions for its end members in this study we discard the vague term of atmospheric sulfate by recognizing two major sulfate sources on the basis of their formation pathways primary and secondary sulfate primary sulfate including those from rock weathering sea salt and volcanic ash leachates do not have an 17o anomaly secondary sulfate derived from the oxidation of reduced sulfur gases biological or volcanic emissions by atmospheric ozone or hydrogen peroxide however has an 17o anomaly we developed a method to extract water soluble anions sequentially or entirely from bulk soil samples and analyzed the sulfate concentrations and 17o anomalies for four geographically representative soil profiles in the central atacama desert 23 s to 25 5 s we found that sequential sulfate extractions on the same soil sample produce sulfate with decreasing 17o values except for a positive bulge at 20 to 50 cm in depth there is a general increase in the 17o value for total sulfate with soil depth for all the four soil profiles that we examined these findings are consistent with the hypothesis that secondary sulfates 17o anomalous sulfates are more soluble and thus preferentially leached in liquid water than primary sulfate the finding also warns that incomplete sulfate extraction from sulfate rich soils yields unpredictable results we infer a 17o value of 4 6 for secondary sulfate based on data from partial sulfate extraction experiments total contribution of secondary sulfate in the central atacama desert is estimated to range from 9 to 24 with the highest percentage in the central depression

occurrence frequency of convective gravity waves during the north american thunderstorm season 1 convective gravity waves are an important driver of the equator to pole circulation in the stratospheric summer hemisphere but their nature is not well known previous studies showing tight relationships between deep convection and convective waves mainly focus on tropical latitudes for midlatitudes most analyses are based on case studies here we present a new multiyear occurrence frequency analysis of convective waves at midlatitudes the study is based on radiance measurements made by the atmospheric infrared sounder airs satellite experiment during the north american thunderstorm season may to august in the years 2003 2008 for this study we optimized an existing algorithm to detect deep convection in airs data to be applicable at midlatitudes we also present a new detection algorithm for gravity waves in airs data based on a variance filter approach for 4 3 m brightness temperatures the new algorithm can detect plane wave perturbations in the altitude range from 20 to 65 km with vertical wavelengths larger than 15 km and horizontal wavelengths from 50 to 1000 km by analyzing spatial and temporal correlations of the individual airs observations it can be shown that more than 95 of the observed gravity waves in a core region over the north american great plains are related to deep convective clouds i e are likely being classified appropriately as convective waves we conclude that the core region is a good location to observe and characterize the properties of convective waves at midlatitudes the statistical analyses presented here are also valuable to validate parameterization schemes for convective gravity waves for completeness it should be mentioned that our analyses cover not only the u s midwest but the north american continent as well as the surrounding ocean regions in general our analysis also reveals interesting details about tropical convection and related gravity wave activity as well as the capability of the airs instrument to observe these

climatology of mesospheric gravity wave activity over urbana illinois 40 n 88 w a 5 year 1991 1995 climatology of mesospheric gravity wave activity observed with the urbana medium frequency mf radar is presented we focus on the monthly mean horizontal wind variances associated with gravity waves with observed periods between 10 min and 8 hours these results are compared with the seasonal characteristics from other gravity wave observations the total wave variance displays a dominant semiannual variation maxima summer winter minima spring fall below 87 km with little seasonal variation above 87 km the zonal wave variance exceeds the meridional wave variance except around regions of zonal wind reversal in all seasons the observed variance scale height is greater than that of a nondissipating wave field a simple zero mean wind model based on linear saturation theory is found to be inadequate in reproducing the seasonal characteristics of the observed wave variances an alternative model based on critical layer filtering by a height dependent wind field can reproduce the observed semiannual oscillation in the wave variance given a specific source input

gravity wave characteristics over tromelin island during the passage of cyclone hudah 1 the time and spatial evolution of gravity wave characteristics are analysed using wavelets in vertical profiles of temperature and winds at tromelin island 15 53 s 54 31 e during the passage of the intense tropical cyclone hudah in the southern ocean indian basin in 2000 inertia gravity waves were observed in the upper troposphere and the lower stratosphere with dominant vertical wavelengths of 1 5 3 km horizontal wavelengths 2000 km and periods of 0 6 1 6 days large amounts of gravity wave energy were detected during landfalls of the tropical cyclone the distribution of total energy indicates that mesoscale convective structures such as tropical cyclones are important gravity wave sources in the upper troposphere

mesoscale disturbances in the tropical stratosphere excited by convection observations and effects on the stratospheric momentum budget abstract the importance of the momentum flux of topographically generated mesoscale gravity waves to the extratropical middle atmosphere circulation has been well established for over a decade estimates of the zonal forcing due to tropical mesoscale gravity waves however are hampered by lack of data on their primarily convective sources the advent of aircraft measurements over tropical convective systems now makes such estimates possible without the use of ad hoc assumptions about amplitudes and phase speeds aircraft measurements from nasa s 1980 panama and 1987 step australia missions show that convectively generated disturbances observed just above the tropopause have horizontal scales comparable to those of the underlying anvils about 50 100 km with peak to peak isentropic surface variations of about 300 400 m satellite imagery of tropical anvil evolution indicates a typical lifetime of about five hours assuming that each convective system s impact on the stratosphere can be modeled as a time

intercomparison of gravity waves in global convection permitting models abstractlarge uncertainties remain with respect to the representation of atmospheric gravity waves gws in general circulation models gcms with coarse grids insufficient parameterizations resul

more than ten million years of hyper aridity recorded in the atacama gravels abstract the atacama desert s hyper aridity is closely linked to the development of world class copper and nitrate iodine ores and to regional tectonics and global paleoclimate changes in the cenozoic era the timing when the hyper aridity commenced remains controversial with proposed ages ranging from late oligocene to pleistocene in this study we provide an independent constraint on the initiation of atacama hyper aridity utilizing a 100 m deep profile within the atacama gravels and underneath porphyry copper deposit in spence northern chile the overall high concentration of sulfate up to 10 wt and a multimodal distribution of water soluble salt sulfates chlorides and nitrates indicate multiple generations of sedimentation and salt accumulation events under semi arid to hyper arid climate conditions the multiple sulfate isotope compositions 17o 18o 34s of the upper section 15 0 to 34 5 m are close to those of modern hyperarid surface sulfates while the lower section 34 5 to 65 m displays a depth dependent isotope trend that is best interpreted as marking a period of climate change from semi arid to hyper arid when these data are combined with new chronological 40ar 39ar dates obtained from a volcanic ash layer at depth of 28 0 m our results show that hyper arid condition in the atacama desert was prevailing at least prior to 9 47 ma and may go back as old as the middle miocene

stretching the envelope of past surface environments neoproterozoic glacial lakes from svalbard the oxygen isotope composition of terrestrial sulfate is affected measurably by many earth surface processes during the neoproterozoic severe snowball glaciations would have had an extreme impact on the biosphere and the atmosphere here we report that sulfate extracted from carbonate lenses within a neoproterozoic glacial diamictite suite from svalbard with an age of similar to 635 million years ago falls well outside the currently known natural range of triple oxygen isotope compositions and indicates that the atmosphere had either an exceptionally high atmospheric carbon dioxide concentration or an utterly unfamiliar oxygen cycle during deposition of the diamictites

rare sulfur and triple oxygen isotope geochemistry of volcanogenic sulfate aerosols we present analyses of stable isotopic ratios 17 o 16 o 18 o 16 o 34 s 32 s and 33 s 32 s 36 s 32 s in sulfate leached from volcanic ash of a series of well known large and small volcanic eruptions we consider eruptions of mt st helens washington 1980 1 km 3 mt spurr alaska 1953 1 km3 gjalp iceland 1996 1998 1 km 3 pinatubo phillipines 1991 10 km 3 bishop tuff long valley california 0 76 ma 750 km 3 lower bandelier tuff toledo caldera new mexico 1 61 ma 600 km 3 and lava creek and huckleberry ridge tuffs yellowstone wyoming 0 64 ma 1000 km 3 and 2 04 ma 2500 km 3 respectively this list covers much of the diversity of sizes and the character of silicic volcanic eruptions particular emphasis is paid to the lava creek tuff for which we present wide geographic sample coverage this global dataset spans a significant range in 34 s 18 o and 17 o of sulfate 29 30 and 3 3 respectively with oxygen isotopes recording mass independent 17 o 0 2 and sulfur isotopes exhibiting mass dependent behavior products of large eruptions account for most of these isotopic ranges sulfate with 17 o 0 2 is present as 1 10 m gypsum crystals on distal ash particles and records the isotopic signature of stratospheric photochemical reactions sediments that embed ash layers do not contain sulfate or contain little sulfate with 17 o near 0 suggesting that the observed sulfate in ash is of volcanic origin mass dependent fractionation of sulfur isotopic ratios suggests that sulfate forming reactions did not involve photolysis of so2 like that inferred for pre 2 3 ga sulfates from archean sediments or antarctic ice core sulfate associated with few dated eruptions even though the sulfate sulfur isotopic compositions reflect mass dependent processes the products of caldera forming eruptions display a large 34 s range and exhibit fractionation relationships that do not follow the expected equilibrium slopes of 0 515 and 1 90 for 33 s 32 s vs 34 s 32 s and 36 s 32 s vs 34 s 32 s respectively the data presented here are consistent with modification of a chemical mass dependent fractionation of sulfur isotopes in the volcanic plume by either a kinetic gas phase reaction of volcanic so 2 with oh and or a rayleigh processes involving a residual rayleigh reactant volcanic so 2 gas rather than a rayleigh product these results may also imply at least two removal pathways for so 2 in volcanic plumes above zero 17 o values and their positive correlation with 18 o in sulfate can be explained by oxidation by high 18 o and high 17 o compounds such as ozone and radicals such as oh that result from ozone break down large caldera forming eruptions have the highest 17 o values and the largest range of 18 o which can be explained by stratospheric reaction with ozone derived oh radicals these results suggest that massive eruptions are capable of causing a temporary depletion of the ozone layer such depletion may be many times that of the measured 3 8 depletion following 1991 pinatubo eruption if the amount of sulfur dioxide released scales with the amount of ozone depletion

some effects of model resolution on simulated gravity waves generated by deep mesoscale convection abstract over the past decade numerous numerical modeling studies have shown that deep convective clouds can produce gravity waves that induce a significant vertical flux of horizontal momentum such studies used models with horizontal grid spacings of o 1 km and produced strong gravity waves with horizontal wavelengths greater than about 20 km this paper is an examination of how simulated gravity waves and their momentum flux are sensitive to model resolution it is shown that increases in horizontal resolution produce more power in waves with shorter horizontal wavelengths this change in the gravity waves spectra influences their vertical propagation in some cases gravity waves that were vertically propagating in coarse simulations become vertically trapped in fine simulations which strongly influences the vertical flux of horizontal momentum

a strontium and sulfur isotopic study of permo triassic evaporites in the northern calcareous alps austria pervasively deformed permian and to a lesser extent triassic evaporites of the northern calcareous alps form a tectonic melange collectively known as alpine haselgebirge isotopic compositions of s and sr and trace element concentrations of sr and ba in ca sulfate minerals were investigated in terms of their stratigraphic and paleoenvironmental significance the majority of the samples yielded 34s values ranging from 9 8 to 13 8 indicating precipitation from late permian seawater with local modifications due to bacterial sulfate reduction bsr 87sr86sr ratios of these samples range widely from 0 7070 to 0 7098 but most samples show sr isotope values between 0 7070 and 0 7074 overlapping with the accepted late permian seawater values comparison of both s and sr isotopic compositions of individual samples reveals distinct trends of isotopic enrichment and depletion that can be linked to early diagenetic bsr mixing with continental surface or groundwaters and burial diagenesis concentrations of sr tend to be lower and ba values show a tendency toward values higher than those reported from marine evaporites implying variable diagenetic alteration triassic evaporites are volumetrically less important in the haselgebirge than their permian counterparts and are characterized by marine upper scythian to lower anisian s and sr isotope values in three localities hitherto unknown inclusions of these triassic evaporites were identified within the haselgebirge melange

gravity wave generation in the lower stratosphere due to passage of the typhoon 9426 orchid observed by the mu radar at shigaraki 34 85 n 136 10 e 1 intense gravity wave activities were investigated in the lower stratosphere during the typhoon 9426 strong vertical winds were observed just a few hours before the arrival of the typhoon center at the mu radar site about 30 min to 1 hour after the typhooncenter had passed a considerable reduction in vertical wind amplitude was detected dominant gravity waves showed time period in the range of 7 8 min 15 min and 40 60 min in the upper troposphere and lower stratosphere in the vicinity of the central region of the typhoon a gravity wave was observed which was monochromatic in nature with a vertical wavelength 3 km between 1 5 km and 23 km height in the lower stratosphere the horizontal wavelength for the prominent period was detected in the range of 10 15 km for 15 min wave period and 25 50 km for 40 60 min wave period the vertical wavelength of these waves was examined from 2 5 km to 4 0 km in the horizontal direction the intrinsic group velocity was estimated between 9 2 and 11 2 m s near the tropopause the average direction of group velocity was assessed at about 20 3 from the horizontal the generation of gravity wave like features in the lower stratosphere is believed induced by convection as the low temperature of the clouds indicates a deep penetration over the radar region as seen in the satellite gms images index terms 3314 meteorology and atmospheric dynamics convective processes 3334 meteorology and atmospheric dynamics middle atmosphere dynamics 0341 0342 3329 meteorology and atmospheric dynamics mesoscale meteorology 3384 meteorology and atmospheric dynamics waves and tides 6952 radio science radar atmospheric physics keywords convective updrafts gravity waves troposphere lower stratosphere

mass independent isotopic signatures of volcanic sulfate from three supereruption ash deposits in lake tecopa california abstract hundreds to thousands of megatons of sulfur dioxide released by supereruptions can change chemical and physical properties of the atmosphere and thus induce climate perturbations we present oxygen and sulfur isotope analyses of sulfate in 48 volcanic ash samples and 26 sediment samples from dry lake beds in the tecopa basin california usa these ash layers represent three supereruptions including the 0 64 ma lava creek tuff 2 04 ma huckleberry ridge tuff and 0 76 ma bishop tuff mass independent oxygen signatures 17o up to 2 26 that are present in these ash units and not in associated sediments indicate oxidation of volcanic so2 by mass independent ozone and its products in this study we consider the formation deposition preservation and dilution of mass independent volcanic sulfate mivs using the isotopic compositions of the sulfates we construct a mixing model that demonstrates that the main source of sulfate in lake tecopa is mass dependent sediment derived sulfate mdsds 77 however ash beds still preserve up to 23 of mivs that initially had undiluted 17o value around 8 and 33s as low as 0 35 and 36s up to 1 08 therefore despite potential dilution by mdsds the mivs signatures can be preserved in the geologic record for few million years if deposited as gypsum in arid environments alkaline or saline lake the oxygen and sulfur mass independent signatures of the volcanic sulfates indicate that photolysis and oxidation of volcanic so2 has been achieved in the upper atmosphere since only supervolcanic eruptions were shown to generate massive amount of mass independent sulfate it requires that up to 20 60 of the global ozone layer is consumed as a result of supervolcanic so2 released this may occur as a result of a strong physical and chemical degradation of the tropopause we speculate that the distinction between the high troposphere and the low stratosphere at least locally could be erased by supereruptions and recorded by mivs