a shear instability seeding mechanism for quasiperiodic radar echoes the quasiperiodic echoes with periods in the range of 1 10 minutes originally discovered at the middle and upper atmosphere mu radar in japan in the early 1990s are now known to be a common feature of midlatitude sporadic e a possible role of shear instabilities and the associated kelvin helmholtz structure in seeding the plasma instabilities that produce the radar echoes is suggested in this paper the proposed mechanism has the advantage that the seed structure is generated in situ as part of the same neutral wind structure that serves to initiate the generation of the sporadic e layer in addition the range of observed periods can easily be explained since the kelvin helmholtz structure is embedded in the shear flow and moves with the mean flow in the shear layer the period observed in the ground based frame is simply a product of the horizontal wavelength and the mean flow velocity at the center of the disturbance finally a typical feature of the radar observations has been that the quasiperiodic structure often ebbs and wanes in intensity over a period of 30 to perhaps 60 min recent simulations of unstable neutral shears show that the timescale for the build up and eventual restabilization of the shear flow is 30 40 min comparable to the timescale found in the observations

characteristics of mesospheric gravity waves over the southeastern tibetan plateau region the tibetan plateau tp known as third pole of the earth has important influences on global climates and local weather an important objective in present study is to investigate how orographic features of the tp affect the geographical distributions of gravity wave gw sources three year oh airglow images november 2011 to october 2014 from qujing 25 6 n 103 7 e were used to study the characteristics of gws over the southeastern tp region along with the almost concurrent and collocated meteor radar wind measurements and temperature data from saber timed satellite the propagation conditions of three types of gws freely propagating ducted or evanescent were estimated most of gws exhibited ducted or evanescent characteristics almost all gws propagate southeastward in winter the gw propagation directions in winter are significantly different from other airglow imager observations at northern middle latitudes wind data and convective precipitation fields from the european centre for medium range weather forecasts reanalysis data are used to study the sources of gws on the edge of the tp using backward ray tracing analysis we find that most of the mesospheric freely propagating gws are located in or near the large wind shear intensity region 10 km 17 km on the southeastern edge of the tp in spring and winter the averaged value of momentum flux is 11 6 5 2 m2 s2 in winter and 7 5 3 1 m2 s2 in summer this work will provide valuable information for the gw parameterization schemes in general circulation models in tp region

airglow imager observations of atmospheric gravity waves at alice springs and adelaide australia during the darwin area wave experiment dawex 1 the darwin area wave experiment occurred in australia from october to december 2001 an objective was to characterize the atmospheric gravity wave field produced from intense convective activity that is routinely observed around darwin during november and december two airglow imagers were sited at adelaide and at alice springs each located over 1000 km south of darwin waves were observed at the mesopause region propagating predominantly toward the southeast with some going to the northwest but with none observed going from east to west the lack of waves propagating toward the west suggests some wind filtering mechanism below 80 km altitude waves observed over alice springs were analyzed in detail on three nights on 16 november they were seen propagating toward the northwest it is proposed that they were generated by dynamical events associated with a cutoff low pressure system present over southwest australia on 17 and 19 november the observations are consistent with wave generation by convective activity present in the darwin area thus as proposed by walterscheid et al 1999 and hecht et al 2001a the ducting of waves from distant sources is shown to be a viable explanation for the quasi monochromatic waves frequently observed in airglow observations walterscheid et al 1999 suggested that ducting of waves from the extensive region of deep cumulus convection over northern australia explained the strong poleward directionality seen in the summer months the present study suggests that propagation from northern australia is selective and ducted waves from this region may not be the primary source of waves over adelaide when convection is occurring over central australia

trace element degassing and enrichment in the eruptive plume of the 2000 eruption of hekla volcano iceland during its last eruption in february 2000 hekla volcano iceland emitted a sub plinian plume that was condensed and scavenged down to the ground by heavy snowstorms offering the unique opportunity to study the chemistry of the gaseous plume released during highly explosive eruptions in this paper we present results on trace element and minor volatile species sulfates chlorides and fluorides concentrations in snow samples collected shortly after the beginning of the eruption the goal of this study is to better constrain the degassing and mobility of trace elements in gaseous emissions trace element volatility at hekla is quantified by means of enrichment factors ef relative to be well known volatile trace elements e g transition metals heavy metals and metalloids are considerably enriched in the volcanic plume of hekla their abundances are governed by the primary magmatic degassing of sulfate and or halide compounds which are gaseous at magmatic temperature their volatility is however slightly lower than in basaltic systems most likely because of the lower magma temperature and higher magma viscosity at hekla more surprisingly refractory elements e g ree th ba and y are also significantly enriched in the eruptive plume of hekla where their apparent volatility is two orders of magnitude higher than in mafic systems in addition ree patterns normalized to the hekla 2000 lava composition show a significant enrichment of hree over lree suggesting the presence of ree fluorides in the volcanic plume such enrichments in the most refractory elements and ree fractionation are difficult to reconcile with primary degassing processes since ree fluorides are not gaseous at magma temperature ree enrichments at hekla could be attributed to incongruent dissolution of tephra grains at low temperature by f rich volcanic gases and aerosols within the eruptive plume this view is supported by both leaching experiments performed on hekla tephra and thermodynamic considerations on ree mobility in hydrothermal fluids and modeling of glass dissolution in f rich aqueous solutions tephra dissolution may also explain the observed enrichments in other refractory elements e g th y and ba and could contribute to the degassing mass balance of some volatile trace elements provided they are mobile in f rich fluids it thus appears that both primary magmatic degassing and secondary tephra dissolution processes govern the chemistry of eruptive plumes released during explosive eruptions

airglow imaging observations of small scale structures driven by convective instability in the upper mesosphere over tirunelveli 8 7 n 1 airglow imaging observations of broadband oh meinel band emissions made on the night of 20 january 2007 from the tropical indian site tirunelveli 8 7 n 77 8 e reveal large and small scale wave features that are aligned perpendicular to each other and that are associated with gravity wave dynamics the large scale waves were the signatures of propagating quasi monochromatic qm waves whereas the small scale features were identified to be ripples generated by convective instability in the mesosphere lower thermosphere mlt region the qm waves showed consistent propagation toward the northwest direction throughout the observation period of 4 5 hr whereas the ripples that manifested as short lived patches in the airglow images were transient and did not show any prominent phase propagation in addition to these well resolved structures in images we infer the presence of waves with relatively longer observed time periods compared with the observed time period of qm waves from the spectrum of the time series generated with zenith intensity values derived from the images from the complementary wind and temperature data obtained with co located mf radar and sounding of atmosphere with broad band emission radiometry on the thermosphere ionosphere mesosphere energetics and dynamics mission an attempt is made to understand the dynamic processes occurring in the vicinity of the mesopause during the night of 20 january 2007 the uniqueness of the present observations is that there were short lived ripple patches seen in various parts of the sky during the entire observation period of 4 5 hr the precipitation rates obtained by the tropical rainfall measuring mission satellite mission suggest that the deep convective activity occurring over the equatorial eastern indian ocean provided a plausible source mechanism for sustained generation of the waves observed over tirunelveli during this night

evidence of gravity wave ducting in the mesopause region from airglow network observations 1 we present observational evidence of gravity wave ducting and show for the first time that the ducting occurs over large horizontal distances in the mesopause region an optical network of four all sky imagers in japan identified two dimensional patterns of small scale gravity wave bands in oh airglow images on 13 june 2004 the wave signatures clearly showed northward propagation of more than 1800 km over a wide range of latitudes the horizontal wavelength horizontal phase speed and wave period were estimated from the airglow data as 33 4 km 42 8 m s 1 and 13 4 min respectively the wave structure lasted for the whole 5 h airglow observation period simultaneous mf radar wind data and timed saber measurements suggested that the wave was trapped and ducted at the airglow height the ducting likely contributed to the remarkable coherence of the wave as it propagated northward

first observations of poleward large scale traveling ionospheric disturbances over the african sector during geomagnetic storm conditions this paper presents first observations of poleward traveling ionospheric disturbances tids during strong geomagnetic conditions over the african sector by analyzing different data sets we have observed both positive and negative ionospheric responses during the storm period of 08 10 march 2012 considering the african region as a whole three longitudinal sectors were strategically selected to establish the entire regional response on both sides of the geomagnetic equator results show poleward shift in peak total electron content tec enhancements depletions at different times which are associated to large scale tids the observed phenomena are linked to the global ionospheric response and electrodynamics the understanding has been established using data from international gnss service receiver network radio occultation electron density profiles derived e b drift measurements from magnetometer observations and regional ground based and satellite data contrary to other related studies generated regional tec perturbation maps were not enough to show obvious directions of the large scale tids due to insufficient data over the northern hemispheric part of the african sector there appears to be a switch between positive and negative storm phases during the same storm period especially in the southern hemisphere part of the african region where enough data were available however a detailed analysis revealed that the positive storm phase corresponded to the expansion of the equatorial ionization anomaly eia toward some parts of midlatitude regions and possibly with the contribution from low latitude electrodynamics associated to equatorial electrojet while the other part recorded a negative storm phase due to storm induced changes from the auroral origin we have observed a simultaneous occurrence of both poleward and equatorward propagating tids over the african sector during the same geomagnetic storm period our results show that short lived large scale tids are possibly launched by the equatorial electrojet while the eia expansion contributes through modulation to the poleward propagation of the disturbances temporal variation of tec perturbations on a storm day over the entire african sector showed the existence of large scale tids during the main and recovery phases which can travel poleward up to 20 latitude the amplitudes of the tids have range 2 total electron content unit 1 tecu 1016 el m 2 period of 2 h and virtual velocities of 250 59 750 95 m s in midlatitude regions and up to 990 65 m s within the eia region

mesospheric gravity waves over a tropical convective region observed by oh airglow imaging in indonesia 1 from oh airglow imaging observation carried out over one year in indonesia 74 events of gravity waves in the mlt mesosphere and lower thermosphere region were extracted observed period horizontal wavelength and observed horizontal phase speeds of gravity waves were typically 5 13 min 13 45 km and 37 75 m s respectively propagation directions were mostly southward except for the period between december and february when eastward propagation was preferential spatial distributions of tropospheric clouds estimated with gms geostationary meteorological satellite were consistent with the propagation direction of gravity waves i e these clouds mainly existed in the opposite direction to the propagation direction of waves this suggests that horizontal propagation characteristics of the short period gravity waves in the low latitude mlt region are mainly affected by the distribution of the wave sources in the troposphere and the effect of the background mean wind in the middle atmosphere is smaller as it is weaker 20 m s in the equatorial region

an investigation of gravity wave activity in the low latitude upper mesosphere propagation direction and wind filtering horizontal phase speeds of up to 80 m s 1 the large scale band wave patterns horizontal wavelength between 10 and 60 km exhibited a clear seasonal dependence on the horizontal propagation direction propagating toward the southeast during the summer months and toward the northwest during the winter the direction of propagation was observed to change abruptly around the equinox period in mid march and at the end of september using a numerical simulation of gravity wave propagation in a seasonally variable climatological wind field we have determined that the observed anisotropy in the wave propagation directions can be attributed to a strong filtering of the waves in the middle atmosphere by stratospheric winds index terms 0310 atmospheric composition and structure airglow and aurora 3332 meteorology and atmospheric dynamics mesospheric dynamics 3360 meteorology and atmospheric dynamics remote sensing keywords airglow winds gravity waves wind filtering imager

an observational study of easterly waves over the eastern pacific in the northern summer using fgge data abstract fgge revel iii b data provided by the european centre for medium range weather forecasts and the outgoing longwave radiation data measured by satellites are used to investigate observationally relationships between deep cloud activity and large scale meteorological fields during the northern hemisphere summer may september of 1979 over the eastern pacific aside from the summer monsoon area over southern and eastern asia the eastern pacific is the area where strong deep convection frequently develops in the northern summer this is also one of the tropical ocean areas that have been least explored meteorologically a power spectral analysis using the maximum entropy method is made for the meridional wind component at 850 mb at various grid points in the analysis domain for each mouth from may through september the waves with a period of 4 6 days are not only stronger in july and august than those of other months but active in the regions of 100 130 w in the eastern pacific and 130 160 e i

full wave modeling of small scale gravity waves using airborne lidar and observations of the hawaiian airglow aloha 93 o 1s images and coincident na wind temperature lidar measurements measurements were made of mesospheric gravity waves in the oi 5577 a nightglow observed from maui hawaii during the airborne lidar and observations of hawaiian airglow aloha 93 campaign clear monochromatic gravity waves were observed on several nights by using a full wave model that realistically includes the major physical processes in this region we have simulated the propagation of four waves through the mesopause region and calculated the o 1s nightglow response to the waves mean winds derived from na wind temperature lidar observations were employed in the computations wave amplitudes were calculated based on the requirement that the observed and simulated relative airglow fluctuation amplitudes be equal although the extrinsic i e observed characteristics of all four waves studied were quite similar horizontal wavelengths 20 to 30 km periods 9 min horizontal phase speeds 35 to 50 m s 1 the propagation characteristics of the waves are all quite different due to the different background mean winds through which the waves propagate three of the waves encounter critical levels in the mesopause region for two of these waves the upward propagation beyond the 97 km level is severely impeded by their critical levels because the local value of the richardson number exceeds unity there the third wave is not severely attenuated at its critical level because the richardson number there is about 0 25 the fourth wave does not encounter a critical level although it is strongly doppler shifted to low frequencies over a limited height range by the mean winds it appears to be able to propagate at least to the 110 km level essentially unimpeded this study demonstrates that an accurate description of the mean winds is an essential requirement for a complete interpretation of observed wave driven airglow fluctuations the study also emphasizes that although the measured extrinsic properties of waves may be similar their propagation to higher altitudes depends very sensitively on the mean winds through which the waves propagate

statistical study of short period gravity waves in oh and oi nightglow images at two separated sites 1 using airglow images of the near infrared oh band 720 910 nm and oi 557 7 nm line we investigated seasonal latitudinal and local time variations of short period gravity waves the images were obtained at two locations in japan that are 1200 km apart rikubetsu 43 5 n 143 8 e and shigaraki 34 9 n 136 1 e between october 1998 and october 1999 our analysis has focused on small scale gravity waves with wavelengths less than 40 km and dominant phase speeds of 20 50 m s wave occurrences for both oh and oi at rikubetsu and shigaraki are significantly higher than 60 with a slightly larger value in summer the occurrences increase from evening to midnight there are no obvious local time dependencies in horizontal wavelength propagation direction and phase speed the propagation directions in summer are either northward or northeastward at both locations however in winter the propagation directions at rikubetsu are generally westward nw w and sw whereas those at shigaraki are only southwestward from simultaneous wind observation by the mf radars at wakkanai 45 4 n 141 7 e and yamagawa 31 2 n 130 6 e we discuss possible influences of doppler and thermal ducting wind filtering and source distribution of gravity waves propagating from the lower atmosphere to the airglow heights in the mesopause region

the origin of the calcites from pb zn veins in the harz mountains federal republic of germany abstract studies of the ree distribution in calcites from hydrothermal banded pb zn mineralizations as well as in calcites from pelitic and psammitic unmetamorphosed rocks and magmatites of the harz mountains revealed that the calcite of the banded ores crystallized from hybrid magmatic metamorphic solutions these were rather rich in ree3 fe3 and probably zn2 and pb2 ion concentrations the absence of any negative eu anomalies points to oxidizing conditions the sulphides have crystallized from a different solution it is suggested that the necessary hs rich solutions stem from near surface hydrothermal convection cells set up by nearby granitic intrusions the alternating deposition of calcite and sulphide banded ores may be explained by assuming that farther away from the intrusions the hs rich solutions were intermittedly admixed with the hybrid fluids this caused a decrease in temperature an interruption of calcite deposition and sulphide mineralization near the intrusion continuous mixing of these two fluids became more common and consequently banded ores are rather rare

an investigation of intrinsic gravity wave signatures using coordinated lidar and nightglow image measurements simultaneous observations of gravity waves using an na wind temperature lidar and a multi wavelength all sky nightglow imager were obtained for the first time during the aloha 93 campaign a novel investigation of intrinsic wave parameters has been made by combining measurements of the horizontal wave components imaged in four nightglow emissions height range 80 100 km with na lidar soundings of the horizontal wind field and temperature profiles over the same height interval on october 19 both instruments registered marked monochromatic wave motions the intrinsic periods of several of these waves have been determined and were found to vary considerably with altitude often resulting in a significant increase over their observed wave periods it is shown that these two instrumental techniques generally sampled different regions of the gravity wave spectrum the lidar exhibiting most sensitivity to short vertical wavelength waves less than about 10 km while the imager was most responsive to larger vertical wavelength waves this study illustrates the significant advantages of combining wind temperature lidar and multi wavelength image observations for intrinsic gravity wave measurements

doppler ducting of atmospheric gravity waves atmospheric gravity waves are subject to horizontal ducting in a stably stratified atmosphere that contains levels of wind maximum or minimum quite apart from any superimposed consequences of vertical variation of stability and quite apart from the existence or otherwise of critical levels the process doppler ducting is examined here for two prototype cases an isolated wind maximum and a wind minimum at ground level and for two more realistic model cases a strong tropospheric jet and a nocturnal boundary layer jet the wave structure modal behavior and dispersion curves of all four are very similar it is argued that doppler ducting is available to a part of the gravity wave spectrum in all real circumstances and that it should be considered as a possible candidate whenever observations indicate that some ducting process is operative one particular wave event is discussed in some detail and it is shown that doppler ducting in its simplest form provides a plausible alternative to a more complicated ducting process which involved critical levels and energy leakage previously inferred doppler ducting is available equally to gravity waves in the oceans when background currents vary with depth

on the nature of short period mesospheric gravity wave propagation over halley antarctica 1 as part of a collaborative program between british antarctic survey and utah state university measurements were made using an all sky airglow imager located at the u k halley station 76 s 27 w during the 2000 and 2001 austral winter seasons from april through to early september a co located imaging doppler interferometer was utilized to obtain coincident wind measurements for a total of 171 wave events this study comprises the first detailed climatological investigation of the propagation nature freely propagating doppler ducted or evanescent of individual quasi monochromatic short period wave events at a high southern latitude distributions of the derived vertical wavelength exhibit an interquartile range from 16 48 km with a median vertical wavelength of 21 km the majority of the wave events were found to be freely propagating waves with only 5 exhibiting a clear doppler ducted signature while 15 of the waves were found to be evanescent in nature although no coincident temperature measurements were available subsequent saber temperature measurements suggest that up to 28 of the measured temperature profiles are capable of providing a ducted environment for the observed wave field this is in sharp contrast to findings at mid and low latitudes where these waves have been shown to be prone to doppler ducted motion it is suggested that the relatively weak wind field and associated tidal wind amplitudes over halley are not capable of forming a significant doppler ducted region to sustain a substantial amount of ducted waves belonging to the detectable spectrum of the airglow imager as these wind fields are comparable to wind fields found at other polar latitudes we hypothesize that the majority of short period gravity waves observed in the polar mesosphere are freely propagating and thus an important source of energy transfer into the mlt region

mean winds and tides in the upper middle atmosphere at urbana 40 n 88 w during 1991 1992 a summary of the first 18 months of continuous wind observations using the urbana medium frequency mf radar is presented emphasis is placed on height time contours of monthly mean winds and on amplitudes and phases of 24 hour and 12 hour tides results are compared with data from other midlatitude stations and models below 85 km monthly mean winds are shown to agree closely with the zonal mean geostrophic wind model cira86 significant discrepancies above 85 km have been noted in comparisons between cira86 and the other mesosphere lower thermosphere mlt radar stations including mf meteor and low frequency lf radars and are also sustained in the observations reported here tidal characteristics are generally consistent with other midlatitude observations although significant differences are noted between urbana and its closest mlt network neighbor station durham 43 n 71 w the mean wind observations provide a context for the gravity wave climatology derived from na lidar observations at urbana and promise to contribute toward improvements of middle atmosphere wind and tidal models

rayleigh lidar observations of quasi sinusoidal waves in the tropical middle atmosphere 1 rayleigh lidar observations of temperature for 2 7 hours on 38 nights during the period of 18 january 5 march 1999 and for 3 hours on 29 nights during 29 february 2 april 2000 in the altitude region of 27 60 km over gadanki 13 5 n 85 e clearly show the dominance of the quasi sinusoidal waves of periods in the range of 6 13 hours in temperature in the tropical middle atmosphere during 1999 the vertical wavelength of these waves ranges from 7 1 to 17 km with a mean value of 12 0 2 4 km while during 2000 it ranges from 5 5 to 17 km with a mean value of 11 4 3 5 km the wave periods estimated from the observations during 1999 are generally greater than the observation period on each night and are estimated to be in the range of 6 5 13 1 hours with an average period of 9 7 1 8 hours which is significantly smaller than the inertial period of 53 hours the amplitudes of these waves are in the range of 1 to 8 k such sinusoidal wave modes are clearly discernible in the temperature profiles for 50 nights of observation another striking feature is that the quasi sinusoidal structure is clearly observed in the equivalent day analysis also indicating only small day to day variability in phase a property that is characteristic of atmospheric tides

gravity wave characteristics in the mesopause region revealed from oh airglow imager observations over northern colorado using 5 years of all sky oh airglow imager data over yucca ridge field station co 40 7 n 104 9 w from september 2003 to september 2008 we extract and deduce quasi monochromatic gravity wave gw characteristics in the mesopause region the intrinsic periods are clustered between approximately 4 and 10 min and many of them are unstable and evanescent gw occurrence frequency exhibits a clear semiannual variation with equinoctial minima which is likely related to the seasonal variation of background wind the anomalous propagation direction in january 2006 with strong southward before major warming starting in 21 january and weak southward propagation afterward was most likely affected by stratospheric sudden warming the momentum fluxes show strongly anticorrelated with the tides with 180 out of phase in the zonal component while in the meridional component the easterly maximum occurred approximately 2 6 h after maximum easterly tidal wind however the anticorrelations are both weakest during the summer the dissipating and breaking of small scale and high frequency gw s components could have a potential impact on the general circulation in the mesopause region

imaging of atmospheric gravity waves in the stratosphere and upper mesosphere using satellite and ground based observations over australia during the twpice campaign 1 during the tropical warm pool international cloud experiment twpice an intense tropical low was situated between darwin and alice springs australia observations made on 31 january 2006 by the atmospheric infrared sounder instrument on the nasa aqua satellite imaged the presence of atmospheric gravity waves agws at approximately 40 km altitude with horizontal wavelengths between 200 and 400 km that were originating from the region of the storm airglow images obtained from alice springs about 600 km from the center of the low showed the presence of similar waves with observed periods of 1 to 2 h the images also revealed the presence of 30 to 45 km horizontal wavelength agws with shorter observed periods of near 15 to 25 min ray tracing calculations show that 1 some of the long wavelength waves traveled on rays without ducting to the altitudes where the observations were obtained and 2 shorter period waves rapidly reached 85 km altitude at a horizontal distance close to the storm thus occurring over alice springs only if they were trapped or ducted the mesospheric inversion layer seen in the measured temperature data almost forms such a trapped region the winds therefore critically control the formation of the trapped region wind profiles deduced from the available data show the plausibility for the formation of such a trapped region variations in the wind however would make ideal trapped region conditions short lived and this may account for the sporadic nature of the short period wave observations

climatology and modeling of quasi monochromatic atmospheric gravity waves observed over urbana illinois from analyzing nine months of airglow imaging observations of atmospheric gravity waves agws over adelaide australia 35 s walterscheid et al 1999 have proposed that many of the quasi monochromatic waves seen in the images were primarily thermally ducted here are presented 15 months of observations from february 1996 to may 1997 for agw frequency and propagation direction from a northern latitude site urbana illinois 40 n as adelaide urbana is geographically distant from large orographic features similar to what was found in adelaide the agws seem to originate from a preferred location during the time period around summer solstice in conjunction with these airglow data there exists mf radar data to provide winds in the 90 km region and near simultaneous lidar data which provide a temperature climatology the temperature data have previously been analyzed by states and gardner 2000 the temperature and wind data are used here in a full wave model analysis to determine the characteristics of the wave ducting and wave reflection during the 15 month observation period this model analysis is applied to this and another existing data set recently described by nakamura et al 1999 it is shown that the existence of a thermal duct around summer solstice can plausibly account for our observations however the characteristics of the thermal duct and the ability of waves to be ducted is also greatly dependent on the characteristics of the background wind a simple model is constructed to simulate the trapping of these waves by such a duct it is suggested that the waves seen over urbana originate no more than a few thousand kilometers from the observation site

characteristics of mesospheric gravity waves over antarctica observed by antarctic gravity wave instrument network imagers using 3 d spectral analyses we have obtained horizontal phase velocity distributions of the gravity waves around 90 km from four antarctic airglow imagers which belong to an international airglow imager instrument network known as angwin antarctic gravity wave instrument network results from the airglow imagers at syowa 69 s 40 e halley 76 s 27 w davis 69 s 78 e and mcmurdo 78 s 167 e were compared using a new statistical analysis method based on 3 d fourier transform matsuda et al 2014 for the observation period between 7 april and 21 may 2013 significant day to day and site to site differences were found the averaged phase velocity spectrum during the observation period showed preferential westward direction at syowa mcmurdo and halley but no preferential direction at davis gravity wave energy estimated by i i was 5 times larger at davis and syowa than at mcmurdo and halley we also compared the phase velocity spectrum at syowa and davis with the background wind field and found that the directionality only over syowa could be explained by critical level filtering of the waves this suggests that the eastward propagating gravity waves over davis could have been generated above the polar night jet comparison of nighttime variations of the phase velocity spectra with background wind measurements suggested that the effect of critical level filtering could not explain the temporal variation of gravity wave directionality well and other reasons such as variation of wave sources should be taken into account directionality was determined to be dependent on the gravity wave periods

characteristics of instabilities in the mesopause region over maui hawaii 1 characteristics of convective and dynamical instabilities in the mesopause region between 85 and 100 km over maui hawaii 20 7 n 156 3 w are investigated using 19 nights 133 hours of high resolution wind and temperature data obtained by the university of illinois na wind temperature lidar during the maui mesosphere and lower thermosphere maui malt campaigns the mean probabilities of convective and dynamical instabilities are observed to be 3 and 10 respectively but there is considerable night to night variation at any given time the probability that an unstable condition is found at some altitudes in the 85 100 km range is 90 the maui malt data exhibit a distinct trend for n2 to increase with wind shear and vice versa this correlation has important implications in the understanding of the development of instabilities the night of 11 april 2002 is studied in detail in order to investigate the spatial and temporal structures of n2 wind shear and convective and dynamical instabilities a close linkage between instability and the mesosphere inversion layers mils is identified most of the convectively and dynamically unstable regions are located above the mils with a tendency for dynamical instability to develop below convective instability it is found that the vertical variations of n2 are often correlated with those of wind shear but with a phase shift such that the maxima and minima of n2 are located 0 5 1 km below those of wind shear because of this shift dynamical instability tends to develop in the region above the maximum wind shear where relatively small n2 is observed to be associated with large wind shear we also found that the wind shear is dominated by the contribution of the meridional wind especially when the wind shear is strong possible mechanisms for the observed features are discussed

all sky imaging observations of mesospheric fronts in oi 557 7 nm and broadband oh airglow emissions analysis of frontal structure atmospheric background conditions and potential sourcing mechanisms 1 all sky imaging observations of distinct large horizontal transient mesospheric structures with a spatial scale of 100 km detected in images of broadband oh and oi 557 7 nm airglow emissions were made over clemson south carolina on the night of 14 15 october 2001 we designate these structures as mesospheric fronts and present a detailed summary of this night series of observations paying particular attention to the details of the different frontal structures the wave like activity seen throughout the night and the background atmospheric conditions these data are compared to other observations of similar mesospheric fronts found in the literature and we seek to understand them in relation to mesospheric bores ducted gravity waves mesospheric wall events and nonlinear gravity wave interactions we find that the observed frontal characteristics and the atmospheric background structure exhibit a close resemblance to previous observations of mesospheric bores owing to this similarity and supported by gravity wave ray tracing experiments we propose a sequence of events that generated the mesospheric fronts observed in the airglow emission furthermore we note this similarity in atmospheric structure suggests a potential means of predicting the occurrence of such mesospheric phenomena

estimating the propagation characteristics of large scale traveling ionospheric disturbances using ground based and satellite data 1 in this article the propagation characteristics of large scale traveling ionospheric disturbances ls tids are estimated during the geomagnetic storm periods of 14 16 may 2005 and 25 27 september 2011 over south africa one and two gps arrays have been independently considered for the storms of 15 may 2005 and 26 september 2011 respectively the average periods of dominant modes 2 5 3 5h in the time series data were determined by applying wavelet analysis on both ionosonde and gps data the consideration of diurnal gps total electron content tec variability from receivers along three different longitude sectors showed a time shift in tec enhancement with increasing latitude the first indication of equatorward motion of the traveling ionospheric disturbances tids the statistical method based on gps radio interferometry employed shows that these tids were mostly propagating nearly equatorward for both storm periods which is consistent with the existing literature about storm induced tids on storm days tid horizontal velocities have been determined in the range of 200 500m s the analysis of diurnal tec response from different stations confirmed that the positive storm effect observed on 15 may 2005 was a result of the large scale tids of wavelength 4000 km on the other hand the estimated wavelengths of ls tids on 26 september 2011 were 2400 3400km between 10 and 17 ut a time lag is observed between the times at which enhancements in tec ionosonde fof2 and hmf2 data are revealed and this has been attributed to the passage of the tid

rare earth element systematics in hydrothermal fluids abstract rare earth element concentrations have been measured in hydrothermal solutions from geothermal fields in italy dominica valles caldera salton sea and the mid atlantic ridge the measured abundances show that hydrothermal activity is not expected to affect the ree balance of either continental or oceanic rocks the ree enrichment of the solutions increases when the ph decreases high temperature solutions 230 c percolating through different rock types may show similar ree patterns

new statistical analysis of the horizontal phase velocity distribution of gravity waves observed by airglow imaging we have developed a new analysis method for obtaining the power spectrum in the horizontal phase velocity domain from airglow intensity image data to study atmospheric gravity waves this method can deal with extensive amounts of imaging data obtained on different years and at various observation sites without bias caused by different event extraction criteria for the person processing the data the new method was applied to sodium airglow data obtained in 2011 at syowa station 69 s 40 e antarctica the results were compared with those obtained from a conventional event analysis in which the phase fronts were traced manually in order to estimate horizontal characteristics such as wavelengths phase velocities and wave periods the horizontal phase velocity of each wave event in the airglow images corresponded closely to a peak in the spectrum the statistical results of spectral analysis showed an eastward offset of the horizontal phase velocity distribution this could be interpreted as the existence of wave sources around the stratospheric eastward jet similar zonal anisotropy was also seen in the horizontal phase velocity distribution of the gravity waves by the event analysis both methods produce similar statistical results about directionality of atmospheric gravity waves galactic contamination of the spectrum was examined by calculating the apparent velocity of the stars and found to be limited for phase speeds lower than 30 m s in conclusion our new method is suitable for deriving the horizontal phase velocity characteristics of atmospheric gravity waves from an extensive amount of imaging data

trace elements and c o isotopes of calcite from carlin type gold deposits in the youjiang basin sw china constraints on ore forming fluid compositions and sources abstract the carlin type gold deposits in the youjiang basin sw china can be further classified into three sub types strata bound fault controlled and diabase associated the compositions and sources of the ore forming fluids for each deposit type are evaluated using the texture of calcite by cl cathode luminescence its chemistry by empa electron probe microanalysis and la icp ms laser ablation inductively coupled plasma mass spectrometry and its c o isotopic compositions by sims secondary ion mass spectroscopy the studied deposits are the stratabound zimudang deposit the fault controlled lannigou deposit and the diabase associated badu deposit calcite in the zimudang and lannigou deposits formed at three different stages pre ore stage pore filling and massive calcite cal 1 late ore stage vein calcite cal 2 associated with realgar and pyrite and post ore stage vein calcite cal 3 calcite in the badu deposit formed in two stages ore stage vein and replacement calcite cal 2 associated with pyrite and post ore stage calcites cal 3 calcite with brighter red cl color has higher mn and lower fe content than calcite with darker red cl color furthermore the higher the total ree content the brighter the cl color the host rocks are characterized by light ree rare earth element enrichments in contrast the ore stage calcite shows middle ree enrichments the ore stage calcite has higher concentrations of fe mn mg si and sr and lower concentrations of cu sb and zn than both the pre and post ore calcite the ranges of carbon pdb and oxygen smow isotope compositions of calcite are from 11 29 to 6 89 and from 16 49 to 22 60 for the zimudang deposit from 13 31 to 2 80 and from 9 12 to 29 71 for the lanningou deposit and from 11 94 to 0 49 and from 10 51 to 18 97 for the badu deposit generally the ore stage calcite has a wider range of 13c and 18o values than the other stage calcite the isotope data indicate that a deep crustal fluid was involved in the formation of all of these three deposits meteoric water containing abundant organic matter was also involved in the formation of the badu deposit as well as the zimudang deposit whereas a basin brine was also involved in the formation of the lanningou deposit

microwave limb sounder observations of gravity waves in the stratosphere a climatology and interpretation high horizontal resolution temperature data from the microwave limb sounder mls are analyzed to obtain information about high intrinsic frequency gravity waves in the stratosphere global climatologies of temperature variance at solstice are computed using six years of data a linear gravity wave model is used to interpret the satellite measurements and to infer information about tropospheric wave sources globally uniform sources having several different spectral shapes are examined and the computed variances are filtered in three dimensional space in a manner that simulates the mls weighting functions the model is able to reproduce the observed zonal mean structure thus indicating that the observations reflect changes in background wind speeds and provide little information about the latitudinal variation of wave sources longitudinal variations in the summer hemisphere do reflect source variations since the modeled variances exhibit much less variation in this direction as a consequence of the zonal symmetry of the background winds a close correspondence between the mls variances and satellite observations of outgoing longwave radiation suggests that deep convection is the probable source for these waves the large variances observed over the tip of south america in winter are most certainly linked to orographic forcing but inferences about wave sources in northern hemisphere winter are difficult to make as a result of the high degree of longitudinal and temporal variability in the stratospheric winds comparisons of model results using different source spectra suggest that the tropospheric sources in the subtropics in summer have a broader phase speed spectrum than do sources at middle latitudes in winter

fluorine in basalts from iceland the fluorine content of icelandic tholeiitic and alkaline basalts matches values found in similar rocks from other areas covariation between fluorine and incompatible minor elements such as potassium or phosphorus is found in evolved tholeiites and alkali basalts lack of such covariation in primitive olivine tholeiites indicates that fluorine and other incompatible minor and trace elements are not controlled by minerals such as amphibole mica or apatite in the mantle residue and that the covariation between these elements in the evolved basalts cannot be inherited from the mantle model calculations on rocks from the langjokull area show that olivine tholeiite suites are if derived by simple fractional crystallization enriched in incompatible elements much in excess of the increase due to crystal removal these observations are taken to indicate that the well documented covariation between fluorine and other incompatible elements is not established until evolution of the basaltic magma has started in crustal holding chambers the constancy of element ratios and enrichment in excess of what can be accounted for by crystal fractionation or incremental addition of new batches of primitive magmas does indicate 1 mineral control involving amphibole mica or apatite and 2 addition of fluorine potassium and phosphorous from an external source it is argued that this source is the crustal envelope of the holding chamber

planetary waves and intraseasonal oscillations at davis antarctica from undersampled time series 1 nine years 1997 to 2005 of nighttime hydroxyl 6 2 band rotational temperatures were measured with a scanning spectrometer over davis station antarctica 68 6 s 78 0 e a novel time series analysis technique is employed to create continuous long term time series and local spectral analysis of these temperature time series was performed to search for planetary wave and intraseasonal oscillations many significant wave signatures were observed coincident observations are found in a comparison between these temperature wave signatures and horizontal wind measurements made from a collocated mf radar several very long term wave signatures 30 to 50 days are seen in the oh temperatures which are absent from the mf radar winds an increase in wave activity is seen in the late winter season interannual variations are also shown indicating a peak in 2002 the year of the southern hemisphere stratospheric warming event

the 1991 eruption of hekla iceland the eruption that started in the hekla volcano in south iceland on 17 january 1991 and came to an end on 11 march produced mainly andesitic lava this lava covers 23 km2 and has an estimated volume of 0 15 km3 this is the third eruption in only 20 years whereas the average repose period since 1104 is 55 years earthquakes as well as a strain pulse recorded by borehole strainmeters occurred less than half an hour before the start of the eruption the initial plinian phase was very short lived producing a total of only 0 02 km3 of tephra the eruption cloud attained 11 5 km in height in only 10 min but it became detached from the volcano a few hours later several fissures were active during the first day of the eruption including a part of the summit fissure by the second day however the activity was already essentially limited to that segment of the principal fissure where the main crater subsequently formed the average effusion rate during the first two days of the eruption was about 800 m3 s 1 after this peak the effusion rate declined rapidly to 10 20 m3 s 1 then more slowly to 1 m3 s 1 and remained at 1 12 m3 s 1 until the end of the eruption site observations near the main crater suggest that the intensity of the volcanic tremor varied directly with the force of the eruption a notable rise in the fluorine concentration of riverwater in the vicinity of the eruptive fissures occurred on the 5th day of the eruption but it levelled off on the 6th day and then remained essentially constant the volume and initial silica content of the lava and tephra the explosivity and effusion rate during the earliest stage of the eruption as well as the magnitude attained by the associated earthquakes support earlier suggestions that these parameters are positively related to the length of the preceeding repose period the chemical difference between the eruptive material of hekla itself and the lavas erupted in its vicinity can be explained in terms of a density stratified magma reservoir located at the bottom of the crust we propose that the shape of this reservoir its location at the west margin of a propagating rift and its association with a crustal weakness all contribute to the high eruption frequency of hekla

maui mesosphere and lower thermosphere maui malt observations of the evolution of kelvin helmholtz billows formed near 86 km altitude 1 small scale less than 15 km horizontal wavelength structures known as ripples have been seen in oh airglow images for nearly 30 years the structures have been attributed to either convective or dynamical instabilities the latter are mainly due to large wind shears while the former are produced by superadiabatic temperature gradients dynamical instabilities produce kelvin helmholtz kh billows which have been known for many years however models and laboratory experiments suggest that these billows often spawn a secondary instability that is convective in nature while laboratory investigations see evidence of such structures the evolution of these instabilities in the atmosphere has not been well documented the maui mesosphere and lower thermosphere maui malt observatory located on mt haleakala is instrumented with a na wind temperature lidar that can detect dynamic or convective instabilities with 1 km vertical resolution over the altitude region from about 85 to 100 km the observatory also includes a fast oh airglow camera sensitive to emissions coming from approximately 82 to 92 km altitude which obtains images every 3 s at sufficient resolution and signal to noise to see the ripples on 15 july 2002 ripples were observed moving at an angle to their phase fronts after a few minutes structures appeared to form approximately perpendicular to the main ripple phase fronts the lidar data showed that a region of dynamical instability existed from approximately 85 5 to 87 km and that the direction of the wind shear in this region was consistent with the phase fronts of the ripple features the motion of the ripples themselves was consistent with the wind velocity at 85 9 km thus in this case the observed ripple motion was the advection of kh billows by the wind the perpendicular structures were seen to be associated with the kh billows they formed at the time when the atmosphere briefly became convectively unstable within the region where the kh billows most likely formed because of this and because the ripples were oriented approximately perpendicular to and moved with the billows we speculate that they are the secondary instabilities predicted by models of kh evolution the primary and perpendicular features were seen to decay into unstructured regions suggestive of turbulence while the formation and decay time appear consistent with models the horizontal wavelength of the perpendicular structures seems to be larger than models predict for the secondary instability features

evolution of a mesospheric bore in a duct observed by ground based double layer imagers and satellite observations over the tibetan plateau region

correlation of homogenization temperatures of accessory minerals from sphalerite bearing deposits and ga ge model temperatures abstract the ga ge ratio in sphalerite can be related to the temperature of the initial fluids from which the sphalerite grew after mixing with various amounts of fluids from different origins the extent of mixing of the two fluids can be qualitatively derived from the pressure corrected homogenization temperature which represents the temperature after mixing of the fluids and the ga ge temperatures of sphalerite which indicates the temperature of the hot metal bearing initial fluids different temperature information strongly indicate that mixing of fluids did occur prior to sulphide formation

low latitude gravity wave variances in the mesosphere and lower thermosphere derived from saber temperature observation and compared with model simulation of waves generated by deep tropical convection a portion of waves generated by deep convection have scales and amplitudes large enough to be detected by space borne instruments we have analyzed temperature data from the sounding of the atmosphere using broadband emission radiometry saber instrument on the thermosphere ionosphere mesosphere energetics dynamics timed satellite for sub tidal scale fluctuations filtering was applied both vertically and horizontally to extract wave variances we have analyzed the altitude region between 70 and 130 km and focus on the variances at equatorial latitudes for the altitude region between 70 and 120 km as a function of season local time intervals geographical location and altitude we find significant variances where convection is particularly prolific intertropical convergence zone and at altitudes where wave trapping is known to be favored e g the lower thermospheric duct the locations of significant variances persist from year to year standard deviations of a few of tens of kelvins are found we have also performed simulations of the response to deep tropical convection with a time dependent high resolution fully compressible dynamical model our simulations give wave amplitudes that agree reasonably well with the observed amplitudes and show layering that is consistent with the observations our main finding is that significant variations seen in timed saber temperature data have a convective wave source and are concentrated in layers where thermal ducts occur

statistical investigation of horizontal propagation of gravity waves in the ionosphere over europe and south africa 1 a statistical investigation into the horizontal propagation of 8 30 min gravity waves gws in the ionosphere over a 1 year period from june 2010 to may 2011 is presented the gws were observed by multipoint continuous doppler sounding systems installed in the czech republic and in the western cape south africa measurements of gw propagation in the ionosphere over south africa have never been presented before simultaneous measurements from nearby ionosondes made it possible to estimate the height of the gw observations and show that the analyzed gws propagated at altitudes from 150 to 250 km the analyzed waves were mainly observed after sunrise and around sunset our statistical study shows that the analyzed gws propagated with horizontal velocities from 70 to 250 m s the average observed horizontal velocities were 100 m s in the local summer and 125 150 m s in the local winter the waves propagated approximately poleward in the local summer whereas roughly equatorward propagation was observed in the local winter westward propagation was rarely observed in the czech republic and eastward southeast propagation was seldom observed in south africa a comparison with neutral wind velocities shows that the analyzed gws propagated approximately against the neutral winds calculated by the hwm07 model the estimated horizontal wavelengths of the analyzed waves were 100 300 km

variability of alkali and heavy metal fluxes released by mt etna volcano sicily between 1991 and 1995 abstract we regularly collected volcanic gases and aerosols at mt etna volcano over a long period 1991 1995 and measured their chemical composition by icp ms based on these data we present new evidence on the high volatility of both alkali and some heavy metals in contrast both lanthanides and actinides are not produced as significant gaseous compounds at magmatic temperatures and can be used as tracers of spattered materials all metals of each chemical family maintained systematic trends during the study period at both summit craters and effusive vents located in the valle del bove during the 1991 1993 eruption during the eruption we observed high metal enrichments at effusive vents these enrichments seem to be characteristic of the secondary degassing of a magma previously degassed under the summit area lower metal enrichments are recorded in aerosols sampled in summit crater plumes according to the primary degassing type occurring at these vents while a primary degassing type still occurs at both bocca nuova and voragine during the post eruptive period sud est crater exhibits a transition from primary to secondary type according to the variations of the volcanic activity level we confirm that the alkali metals fractionate systematically within their family as they cross the melt vapour interface the heavier members being always more enriched than the lighter ones in aerosols we also show that this fractionation is not related to the volcanic activity and the degassing type but seems to be a significant feature of the alkali family itself estimation of new emanation coefficients for rubidium caesium tin and thallium 0 07 0 15 0 50 and 21 respectively yields annual outputs around 1000 t yr 60 t yr 240 t yr and 1600 t yr respectively mount etna is a very important source of metals injected into the atmosphere contributing to the global volcanic budget about 16 for heavy metals and 19 for alkali metals in eruptive periods and only 2 and 4 respectively in quiet periods

element partitioning in calcite as a function of solution flow rate a study on vein calcites from the harz mountains a semi empirical treatment of isothermal element partitioning caused by flow rate dependent calcite growth from hydrothermal solutions yields element ca ratios that are qualitatively similar to those observed in calcite bands of the pb zn banded ores from the harz mountains germany the comparison of the calculations with the analytical results suggests that flow rates varied between episodes of calcite precipitation as well as during formation of individual bands based on a flow rate dependent element partition coefficient changing element ca ratios in precipitates from a hydrotherm are therefore not necessarily indicative of changing compositions of the fluid the variations in element ca ratios to be envisaged could be as much as a factor of three

fluid rock interaction during formation of metamorphic quartz veins a ree and stable isotope study from the rhenish massif germany we have investigated fluid rock interaction processes during formation of metamorphic quartz veins that are abundant in the fold and thrust belt of the rhenish massif southwest germany these veins record two successive assemblages that were formed in a different fluid rock environment which are 1 massive vein filling elongate blocky quartz chlorite apatite albite and 2 open space filling euhedral quartz crystals ankerite dolomite calcite sulfides building on previous work that studied the field relationships mineralogy vein textures fluid inclusion and wall rock alteration features we have performed a detailed ree and stable isotope investigation of vein minerals altered wall rocks selvages and least altered host rock metapelites the ree and oxygen isotope data of vein quartz and altered wall rocks in conjunction with mass balance analysis support the conclusion that local mobilization of material was dominant during formation of the early massive vein filling assemblage but that contributions from advecting fluids were also important the pronounced shift in k na ratios in altered wall rocks and model fluid temperatures that are substantially higher 350 400 c than estimates for the surrounding host rocks clearly point to substantial fluid advection formation of the veins can be essentially explained by a crack flow seal model which involves multiple repetition of vein opening fluid advection and vein sealing events consistent with the elongate blocky textures of massive vein quartz each cycle was initiated with vein opening resulting in enhanced permeability and considerable fluid advection leading to hydrothermal alteration of wall rocks conditions during each cycle then evolved towards a decrease in fluid advection coupled with substantial diffusional leaching of silica from the wall rocks and precipitation in the veins the formation of the later open space filling assemblage records a transition from an overall advection to a diffusion dominated regime this is supported by vein mineral and fluid inclusion textures recording conditions of slow and undisturbed mineral growth fluid inclusion data that point to a thermally equilibrated state 150 200 c and stable isotope data that demonstrate a local source for the vein minerals

geochemical surveillance of magmatic volatiles at popocatepetl volcano mexico surveillance of popocatepetl volcanic plume geochemistry and so 2 flux began in early 1994 after fumarolic and seismic activity increased significantly during 1993 volatile traps placed around the summit were collected at near monthly intervals until the volcano erupted on december 21 1994 additional trap samples were obtained in early 1996 before the volcano erupted again emplacing a small dacite dome in the summit crater abundances of volatile constituents ppm day of cl s total f co 2 hg and as varied but most constituents were relatively high in early and late 1994 however ratios of these constituents to cl were highest in mid 1994 34 s s total in trap solutions ranged from 1 5 to 6 4 lowest values generally occurred during late 1994 13 c co 2 of trap solutions were greatly contaminated with atmospheric co 2 and affected by absorption kinetics when trap data are combined with so 2 flux measurements made through november 1996 popocatepetl released about 3 9 mt so 2 16 mt co 2 0 75 mt hcl 0 075 mt hf 260 t as 2 6 t hg and roughly 200 mt h 2 o near vent gas concentrations in the volcanic plume measured by correlation spectrometer cospec and fourier transform infrared ftir commonly exceed human recommended exposure limits and may constitute a potential health hazard volatile geochemistry combined with petrologic observations and melt inclusion studies show that mafic magma injection into a preexisting silicic chamber has accompanied renewed volcanism at popocatepetl minor assimilation of cretaceous wall rocks probably occurred in mid 1994

observational evidence of wave ducting and evanescence in the mesosphere a collaborative radar and imaging study of gravity waves over the hawaiian islands was performed during october 1993 as part of the airborne lidar and observations of hawaiian airglow 1993 coupling and dynamics of regions equatorial aloha 93 cadre campaign to investigate the propagation characteristics of short period 1 hour waves at nightglow altitudes the horizontal wavelengths and apparent phase speeds of quasi monochromatic wave events were measured in four separate nightglow emissions using data obtained by a high resolution ccd imager this information was correlated with simultaneous mf radar wind measurements over the same height interval 80 100 km to infer intrinsic wave parameters in each case correlating the two data sets allowed the determination of the local vertical wavenumber for each event in particular whether it be real indicative of freely propagating waves or imaginary indicative of ducted or evanescent waves the results of this study indicate a preponderance of ducted or evanescent waves at 80 100 km during the time of the observations with up to 75 of the events recorded exhibiting ducted or evanescent behavior also noted was a tendency for ducted behavior to be more prevalent among waves with shorter horizontal wavelengths in agreement with doppler ducting theory these results suggest that ducted waves are relatively common in the upper mesosphere and lower thermosphere region at least over the mid pacific ocean as small scale waves which are ducted have the potential to travel much longer horizontal distances than freely propagating waves the frequency of their occurrence should be taken into account in efforts to quantify gravity wave effects at these altitudes

textural evolution and trace element chemistry of hydrothermal calcites from archean gold deposits in the hattu schist belt eastern finland indicators of the ore forming environment abstract orogenic style gold mineralizations in the archean hattu schist belt e finland are present in all major host rock lithologies including epiclastic sedimentary rocks volcanic rocks and felsic intrusives the gold deposits are related to extensive quartz dominated vein networks and the gold mineralization occurs as dissemination in altered wall rocks and within hydrothermal quartz veins the quartz dominated veins frequently contain calcite which is also present within the country rocks we analyze and compare the major and trace element chemistry of these calcites and test whether they carry the signatures of the origin of hydrothermal fluids associated with the gold deposits or record fluid interaction with the local wall rocks the calcites show textural growth and chemical zoning considerable chemical variations within samples and the chemical data do show some overlap between the samples all calcites contain dominantly ca with other elements being typically below 2 wt and they are accordingly classified as rather pure calcites amongst minor elements both mg and fe show larger variations than mn the concentrations of most trace elements analyzed are relatively low except for sr and y which can attain values up to 1 wt and 200 ppm respectively some of the trace elements or trace element ratios in hydrothermal calcite including sr y mn la lu n and ree show correlations with the respective host rock lithologies this indicates that interaction between hydrothermal fluids and adjacent and diverse host rocks has strongly affected the trace element chemistry of calcite chemically variable growth zones in large calcite crystals and distinct grain populations within individual samples cannot be readily explained by host rock control but instead they are interpreted to reflect changes in fluid composition over time the hydrothermal calcites have chondrite normalized ree patterns that are mostly hree enriched relative to lree with very few exceptions that show unfractionated flat or lree enriched relative to the hree patterns the ree patterns of the calcites are very different from those of their immediate host rocks suggesting that they are inherited from the hydrothermal fluid s from which they precipitated the hree enrichment relative to the lree visible in the patterns resembles the ree patterns of calcites from hydrothermal vein type deposits of metamorphic origin elsewhere and contrasts with the ree patterns of calcites from magmatic hydrothermal environments the ree patterns of the hydrothermal calcites in the hattu schist belt deposits would therefore be compatible with formation from a fluid system that is essentially derived from metamorphic sources in agreement with conclusions drawn from the fluid inclusion chemistry

new insights into geochemical behaviour in ancient marine carbonates upper jurassic ammonitico rosso novel proxies for interpreting sea level dynamics and palaeoceanography elemental concentrations in phanerozoic sea water are known to fluctuate both in time and space with regard to carbonates precipitated from marine fluids elemental concentrations in the carbonate crystal lattice are affected by a complex array of equilibrium and non equilibrium as well as post depositional alteration processes to assess the potential of carbonate elemental chemostratigraphy seven upper jurassic sections were investigated along a proximal to distal transect across the south east iberian palaeomargin the aim was to explore stratigraphic and spatial variations in calcium strontium magnesium iron and manganese elemental abundances the epicontinental geochemical record is influenced by the combination of continental runoff and a significant diagenetic overprint in contrast the epioceanic geochemical record agrees with reconstructed open marine sea water values reflecting a moderate degree of syn depositional to early marine pore water diagenesis establishing a fair degree of preservation of matrix micrite a thorough statistical approach was applied and elemental associations tested for their environmental significance principal component and hierarchical cluster analyses revealed a persistent relation between carbonate magnesium iron and strontium abundances processes related to early diagenetic nodulation in ammonitico rosso facies most probably account for the incorporation of these elements in the calcium carbonate lattice the clear decoupling of carbonate manganese abundance with respect to the remaining elements is documented and related to high sea floor spreading rates and hydrothermal activity during the late jurassic the investigation of potential time fluctuation of geochemical patterns was approached through variogram computation the observed temporal behaviour is most likely to be forced by relative sea level dynamics reflecting late jurassic palaeoceanographic conditions and potential planetary interactions the data obtained in this study highlight the utility of elemental data from carbonate matrix micrites as geochemical proxies for studying the influence of remote trigger factors

observations of the phase locked 2 day wave over the australian sector using medium frequency radar and airglow data 1 the quasi 2 day wave with a nominal mean period just above 50 h is a significant feature of the 80 100 km altitude region in both hemispheres it becomes particularly prominent in the southern hemisphere summer at midlatitudes where a short time after summer solstice its amplitude rapidly increases and its mean period is found to be approximately 48 h producing an oscillation phase locked in local time this lasts for a few weeks presented here are observations of the meridional winds and airglow over two sites in australia for 4 years during the austral summers of 2003 2006 we show that during those times when the large amplitude phase locked 2 day wave pl tdw is present the diurnal tide greatly decreases this is consistent with the walterscheid and vincent 1996 model in which the pl tdw derives its energy from a parametric excitation by the diurnal tide these data also show that the diurnal tide is more suppressed and the pl tdw amplitude is larger in odd numbered years suggesting a biannual effect the airglow data indicated that for the pl tdw the winds and temperature are nearly out of phase when the pl tdw is present airglow amplitudes can become quite large a result dependent on the local time of the pl tdw maximum the airglow intensity response was in general much larger than what would be expected from the airglow temperature response suggesting that the pl tdw is causing a significant composition change possibly due to minor constituent transport