preface recent developments in microbeam cathodoluminescence with applications to mineralogy this thematic set contains a series of papers arising from a symposium of the same name at the 15th annual goldschmidt conference held at the university of moscow idaho in may of 2005 although luminescence the ability of materials to emit light upon excitation with various kinds of energy is a well established technique in physics and the material sciences its present widespread use in the geosciences was stimulated forty years ago by the introduction of the technique of cathodoluminescence cl to image the internal structure of minerals smith and stenstrom 1965 long and agrell 1965 many minerals exhibit the phenomenon of cl as a result of electron beam interaction a trait that can successfully be applied to the study and interpretation of zoning patterns in minerals and or cementation in rocks e g mariano 1988 the state of the technique of cl up to the end of the last millennium had been laid out in a comprehensive book

aragonite breunnerite calcite and dolomite in the cm carbonaceous chondrites high fidelity recorders of progressive parent body aqueous alteration abstract carbonate minerals in cm carbonaceous chondrite meteorites along with the silicates and sulphides with which they are intergrown provide a detailed record of the nature and evolution of parent body porosity and permeability and the chemical composition temperature and longevity of aqueous solutions fourteen meteorites were studied that range in petrologic subtype from mildly aqueously altered cm2 5 to completely hydrated cm2 0 all of them contain calcite whereas aragonite occurs only in the cm2 5 cm2 2 meteorites and dolomite in the cm2 2 cm2 0 all of the aragonite crystals and most of the calcite and dolomite grains formed during early stages of parent body aqueous alteration by cementation of pores produced by the melting of tens of micrometre size particles of h2o rich ice aragonite was the first carbonate to precipitate in the cm2 5 to cm2 2 meteorites and grew from magnesium rich solutions in the least altered of these meteorites the aragonite crystals formed in clusters owing to physical restriction of aqueous fluids within the low permeability matrix the strong correlation between the petrologic subtype of a meteorite the abundance of its aragonite crystals and the proportion of them that have preserved crystal faces is because aragonite was dissolved in the more altered meteorites on account of their higher permeability and or greater longevity of the aqueous solutions dolomite and breunnerite formed instead of aragonite in some of the cm2 1 and cm2 2 meteorites owing to higher parent body temperatures the pore spaces that remained after precipitation of aragonite dolomite and breunnerite cements were occluded by calcite following completion of cementation the carbonates were partially replaced by phyllosilicates and sulphides calcite in the cm2 5 cm2 2 meteorites was replaced by fe rich serpentine and tochilinite followed by mg rich serpentine in the cm2 1 and cm2 0 meteorites dolomite breunnerite and calcite were replaced by fe rich serpentine and fe ni sulphide again followed by mg rich serpentine the difference between meteorites in the mineralogy of their replacive sulphides may again reflect greater temperatures in the parent body regions from where the more highly altered cms were derived this transition from fe rich to mg rich carbonate replacement products mirrors the chemical evolution of parent body solutions in response to consumption of fe rich primary minerals followed by the more resistant mg rich anhydrous silicates almost all of the cms examined contain a second generation of calcite that formed after the sulphides and phyllosilicates and by replacement of remaining anhydrous silicates and dolomite dedolomitization the ca and co2 required for this replacive calcite is likely to have been sourced by dissolution of earlier formed carbonates and ions may have been transported over metre plus distances through high permeability conduits that were created by impact fracturing

syn and postkinematic cement textures in fractured carbonate rocks insights from advanced cathodoluminescence imaging abstract in calcite and dolomite deposits in fractures transmitted light and optical cathodoluminescence methods detect crack seal texture in some fractures but scanning electron microscope based cathodoluminescence sem cl combined with secondary electron images and element maps reveals crack seal and cement growth textures where previous sem cl imaging methods found massive or featureless deposits in a range of fractured carbonate rocks patterns and textures of calcite and dolomite cements precipitated during and after fracture growth resemble complex accumulation patterns found in quartz in sandstone fractures suggesting that some apparent differences between carbonate mineral and quartz deposits in fractures reflect the limits of previous imaging methods advances in delineating textures in widespread carbonate mineral deposits in fractures provide evidence for growth and occlusion of fracture porosity

mapping potential vorticity dynamics on jupiter i zonal mean circulation from cassini and voyager 1 data maps of ertel potential vorticity on isentropic surfaces ipv and or quasi geostrophic potential vorticity qgpv are well established in dynamical meteorology as powerful sources of insight into dynamical processes involving balanced flow in the present study we derive maps of zonal mean ipv and qgpv in jupiter s upper troposphere and lower stratosphere by making use of a combination of velocity measurements derived from the tracking of cloud features in images from the voyager 1 and 2 and cassini missions and thermal measurements from the voyager 1 iris and cassini cirs instruments ipv and qgpv are mapped and compared for the entire globe between latitudes 55 profiles of zonally averaged pv show some evidence for a step like pattern suggestive of local pv homogenization separated by strong pv gradients in association with eastward jets though on differing scales in the northern and southern hemispheres the northward gradient of pv ipv or qgpv is found to change sign in several places in each hemisphere even when baroclinic contributions are taken into account the relationship of lateral gradients of ipv and qgpv with the corresponding mean zonal flows indicate that the northern hemisphere may be closer to marginal stability with respect to arnol d s second stability theorem than the southern hemisphere copyright 2006 royal meteorological society

jupiter s great red spot as a shallow water system most current models of jupiter s great red spot grs are cast in terms of a two layer model where a thin upper weather layer which contains the vortex overlies a much deeper layer which is meant to represent the neutrally stratified deep atmosphere any motions in the deep layer are assumed to be zonal and steady this two layer model is dynamically equivalent to a one layer model with meridionally varying solid bottom topography called the reduced gravity model specifying the motions or lack thereof in the lower layer of the two layer model is equivalent to specifying the bottom topography and hence the far field potential vorticity in the reduced gravity model current models of the grs start by guessing the deep motions and then proceed to study vortices using the implied bottom topography here using the grs cloud top velocity data we derive the bottom topography up to a constant that depends on the unknown radius of deformation or equivalently the product of the reduced gravity and the mean thickness of the upper layer the bottom topography is inferred from three quantities derived from the velocity data bernoulli streamfunction kinetic energy per unit mass and absolute vorticity all of which are functions only of horizontal position in the reference frame of the vortex far from the vortex potential vorticity versus latitude is calculated from the observed cloud top zonal velocity and the derived bottom topography the results show that the deep atmosphere is in differential motion and that the far field potential vorticity gradient changes sign at several latitudes numerical shallow water experiments are performed using both the derived bottom topography and the bottom topographies prescribed by current models the results of three published studies are reproduced in our numerical experiments each of these models is successful in maintaining a long lived isolated vortex but only the present model yields absolute vorticity profiles along streamlines that agree with those observed for the grs by dowling and ingersoll in all the models large vortices form by merging with smaller vortices in the present observationally based model and in one other published model the smaller vortices arise spontaneously because the observed cloud top zonal velocity profile is unstable these two models require an additional momentum source to maintain the upper layer zonal velocity profile in the other two models the bottom topography stabilizes the zonal velocity profile if dissipation is present the latter two models require an additional source of smaller vortices to maintain the larger one a crucial unanswered question for the present model and for jupiter itself is how the cloud top zonal velocity profile is maintained in its present unstable state

close range ground based hyperspectral imaging for mining applications at various scales review and case studies abstract detailed mapping of mineral phases at centimeter scale can be useful for geological investigation including resource exploration this work reviews case histories of ground based close range hyperspectral imaging for mining applications studies of various economic deposits are discussed as well as techniques used for data correction integration with other datasets and validation of spectral mapping results using geochemical techniques machine learning algorithms suggested for automation of the mining workflow are reviewed as well as systems for environmental monitoring such as gas leak detection three new case studies that use a ground based hyperspectral scanning system with sensors collecting data in the visible near infrared and short wave infrared portions of the electromagnetic spectrum in active and abandoned mines are presented vertical exposures in a carlin style sediment hosted gold deposit an active cu au mo mine and an active asphalt quarry are studied to produce images that delineate the extent of alteration minerals at centimeter scale to demonstrate an efficient method of outcrop characterization which increases understanding of petrogenesis for mining applications in the carlin style gold deposit clay iron oxide carbonate and jarosite minerals were mapped in the copper porphyry deposit different phases of alteration are delineated some of which correspond to greater occurrence of ore deposits a limestone quarry was also imaged which contains bitumen deposits used for road paving aggregate review of current literature suggests use of this technology for automation of mining activities thus reducing physical risk for workers in evaluating vertical mine faces

segmented african lithosphere beneath the anatolian region inferred from teleseismic p wave tomography summary lithospheric deformation throughout anatolia a part of the alpine himalayan orogenic belt is controlled mainly by collision related tectonic escape of the anatolian plate and subduction roll back along the aegean subduction zone we study the deeper lithosphere and mantle structure of anatolia using teleseismic finite frequency p wave traveltime tomography we use data from several temporary and permanent seismic networks deployed in the region approximately 34 000 p wave relative traveltime residuals measured in multiple frequency bands are inverted using approximate finite frequency sensitivity kernels our tomograms reveal segmented fast seismic anomalies beneath anatolia that corresponds to the subducted portion of the african lithosphere along the cyprean and the aegean trenches we identify these anomalies as the subducted aegean and the cyprus slabs that are separated from each other by a gap as wide as 300 km beneath western anatolia this gap is occupied by slow velocity perturbations that we interpret as hot upwelling asthenosphere the eastern termination of the subducting african lithosphere is located near the transition from central anatolia to the eastern anatolian plateau or arabian eurasian collision front that is underlain by large volumes of hot underplating asthenosphere marked by slow velocity perturbations our tomograms also show fast velocity perturbations at shallow depths beneath northwestern anatolia that sharply terminates towards the south at the north anatolian fault zone nafz the associated velocity contrast across the nafz persists down to a depth of 100 150 km hence our study is the first to investigate and interpret the vertical extent of deformation along this nascent transform plate boundary overall the resolved upper mantle structure of anatolia is directly related with the geology and tectonic features observed at the surface of the anatolian plate and suggest that the segmented nature of the subducted african lithosphere plays an important role in the evolution of anatolia and distribution of its tectonic provinces

life cycles of spots on jupiter from cassini images using the sequence of 70 day continuum band 751 nm images from the cassini imaging science system iss we record over 500 compact oval spots and study their relation to the large scale motions the 100 spots whose vorticity could be measured the large spots in most cases were all anticyclonic we exclude cyclonic features chaotic regions because they do not have a compact oval shape but we do record their interactions with spots we distinguish probable convective storms from other spots because they appear suddenly grow rapidly and are much brighter than their surroundings the distribution of lifetimes for spots that appeared and disappeared during the 70 day period follows a decaying exponential with time constant mean lifetime of 3 5 days for probable convective storms and 16 8 days for all other spots extrapolating the exponential beyond 70 days seriously underestimates the number of spots that existed for the entire 70 day period this and other evidences size shape distribution in latitude suggest that these long lived spots with lifetime larger than 70 days are from a separate population the zonal wind profile obtained manually by tracking individual features this study agrees with that obtained automatically by correlating brightness variations in narrow latitude bands porco et al 2003 some westward jets have developed more curvature and some have developed less curvature since voyager times but the number of westward jets that violate the barotropic stability criterion is about the same in the northern hemisphere the number of spots is greatest at the latitudes of the westward jets which are the most unstable regions according to the barotropic stability criterion during the 70 day observation period the great red spot grs absorbed nine westward moving spots that originated in the south equatorial belt seb where most of the probable convective storms originate although the probable convective storms do not directly transform themselves into westward moving spots their common origin in the seb suggests that moist convection and the westward jet compose a system that has maintained the grs over its long lifetime

experimental and numerical studies of an eastward jet over topography motivated by the phenomena of blocked and zonal flows in earth s atmosphere we conducted laboratory experiments and numerical simulations to study the dynamics of an eastward jet flowing over wavenumber two topography the laboratory experiments studied the dynamical behaviour of the flow in a barotropic rotating annulus as a function of the experimental rossby and ekman numbers two distinct flow patterns resembling blocked and zonal flows in the atmosphere were observed to persist for long time intervals earlier model studies had suggested that the atmosphere s normally upstream propagating rossby waves can resonantly lock to the underlying topography and that this topographic resonance separates zonal from blocked flows in the annulus the zonal flows did indeed have super resonant mean zonal velocities while the blocked flows appear subresonant low frequency variability periodic or irregular was present in the measured time series of azimuthal velocity in the blocked regime with dominant periodicities in the range of 6 25 annulus rotations oscillations have also been detected in zonal states with smaller amplitude and similar frequency in addition over a large region of parameter space the two flow states exhibited spontaneous intermittent transitions from the one to the other we numerically simulated the laboratory flow geometry in a quasi geostrophic barotropic model over a similar range of parameters both flow regimes blocked and zonal were reproduced in the simulations with similar spatial and temporal characteristics including the low frequency oscillations associated with the blocked flow the blocked and zonal flow patterns are present over wide ranges of forcing topographic height and bottom friction for a significant portion of parameter space both model flows are stable depending on the initial state either the blocked or the zonal flow is obtained and persists indefinitely showing the existence of multiple equilibria

the influence of topography on the stability of jets in this article the effect shelflike topography has on the stability of a jet that flows along the smooth shelf is addressed the linear stability problem is solved to determine for which nondimensional parameters a shelf can either destabilize or stabilize a jet these calculations reveal an intricate dependence of growth rate on topography in particular the authors determine that retrograde topography with the shallow water on the left always stabilizes the jet in relation to the flat bottom equivalent whereas prograde topography with the shallow water on the right can either stabilize or destabilize the jet depending on the particular values of the rossby number and topographic parameters for rossby numbers of order 1 and larger prograde topography is strictly stabilizing for small rossby numbers small amplitude topography destabilizes whereas large topography stabilizes the nonlinear evolution of these instabilities is explored to confirm the predictions from the linear theory and also to illustrate how stabilization is directly related to fluid transport across the shelf

three dimensional vp and vp vs structure at loma prieta california from local earthquake tomography p and s p times from local earthquakes and p times from explosions at seismic stations in the vicinity of the 1989 loma prieta earthquake are inverted simultaneously to produce three dimensional images of vp and vp vs structure along the rupture zone the results confirm the presence of the major heterogeneities identified in previous studies using p waves only including high vp along the rupture in areas of significant slip and a low velocity wedge along the san andreas at the se edge of the rupture a change in rock properties evidenced by a significant vp vs increase equal to a 30 poisson s ratio increase from the middle crust to the upper crust may have been responsible for the upward termination of the main shock rupture we speculate that the deep high vp body that lies along the se portion of the rupture zone consists of two bodies based on model results indicating that the sw part of the body has relatively high vp vs while the ne part has relatively low vp vs

jupiter s zonal winds are they bands of homogenized potential vorticity organized as a monotonic staircase the east west striped pattern of clouds in jupiter s weather layer is accompanied by a zonal flow containing 12 eastward going jet streams alternating in latitude with westward going jet streams based on theory simulation and observations of the earth s oceans and atmosphere it is conjectured that jupiter s weather layer is made of bands of constant potential vorticity pv where the interfaces between bands are at the latitudes of the maxima of the eastward going jet streams it is speculated that the mixing of pv on jupiter is analogous to the mixing of salt in the ocean by the phillips effect which causes the salt density to form a monotonic staircase it is hypothesized that the pv in jupiter s weather layer is also a staircase decreasing from north to south pv is a function of vorticity as well as parameters with unknown values e g the vertical stratification and the zonal flow beneath the observable weather layer therefore these hypotheses cannot be tested directly using an atmospheric model that contains these unknown parameters we solved the inverse problem and found values of the unknown parameters and their uncertainties that best fit jovian observations the unknown parameters influence how the zonal flow interacts with large vortices e g the great red spot grs the largest and longest lived jovian vortex centred at 23 s and the oval ba the second largest vortex centred at 33 s although we found that the pv distribution is approximately piecewise constant and that the peaks of the eastward going jet streams are at the latitudes of pv interfaces there is also a pv interface at 20 s where there is a westward going jet stream we find that the zonal pv is not a monotonic staircase due to the backwards interface at 20 s we show that this backwards interface is necessary to make the grs nearly round and that without that interface the red spot would be highly elongated in the east west direction and probably unstable

dynamics of the atmospheres of the outer planets post voyager measurement objectives current knowledge about dynamics and thermal structure on the outer planets is reviewed with the aim of identifying important measurements which should be made in the post voyager era the existence of jets and cloud bands is the puzzle that underlies all others discussion focuses on the particular case of jupiter because documentation is most complete recent dynamical work has successfully reproduced much of the behavior of jets and spots with simple models that contain few parameters it is argued that the gross dynamical parameters such as density stratification and rotation rate are the keys to their behaviors rather than the particular specifics of radiative forcing cloud distributions thermodynamic transformations voyager data have shown that the jet systems decay with height in the region above the visible clouds therefore the highest priority must be given to establishing dynamical parameters that characterize levels within and beneath the clouds these require determination of the deep structure of the jets of the density stratification and of the horizontal density contrasts the deep regions are not easily accessible and these measurements present challenging opportunities indirect inferences about the controlling processes may sometimes be possible by observing waves and other activity in the more easily accessible stratosphere and some of these issues are also discussed

imaging the shallow crust with local and regional earthquake tomography 1 while active source imaging seismic reflection refraction is typically used to image the shallow crust these techniques tend to suffer from energy penetration problems in complex tectonic regimes resulting in poor imaging further active sources such as air guns or vibroseis tend to be band limited resulting in poor signal to noise ratio at low frequencies 1 10 hz recent studies suggest that earthquake data may be able to solve these imaging problems however conventional earthquake tomography typically aims to image the upper mantle and lithosphere where typical station spacing tens of km and array aperture hundreds of km have resulted in the maximum resolution in this study we take advantage of the small scale and 250 m station spacing of the labarge passive seismic experiment to determine whether local and regional earthquake tomographies can be used to constrain structure in the top 5 km of the crust we also study how the inclusion of finite frequency effects impacts the final images our results indicate that local and regional events provide substantial improvements over teleseismic events alone with approximately 500 m resolution both vertically and laterally in the upper most 5 km we also find that inclusion of finite frequency data between 1 and 10 hz plays a key role in maintaining resolution in the shallowest portion of the model

prediction of a global climate change on jupiter jupiter s atmosphere as observed in the 1979 voyager space craft images is characterized by 12 zonal jet streams and about 80 vortices the largest of which are the great red spot and three white ovals that had formed1 in the 1930s the great red spot has been observed2 continuously since 1665 and given the dynamical similarities between the great red spot and the white ovals the disappearance3 4 of two white ovals in 1997 2000 was unexpected their longevity and sudden demise has been explained5 however by the trapping of anticyclonic vortices in the troughs of rossby waves forcing them to merge here i propose that the disappearance of the white ovals was not an isolated event but part of a recurring climate cycle which will cause most of jupiter s vortices to disappear within the next decade in my numerical simulations the loss of the vortices results in a global temperature change of about 10 k which destabilizes the atmosphere and thereby leads to the formation of new vortices after formation the large vortices are eroded by turbulence over a time of 60 years consistent with observations of the white ovals until they disappear and the cycle begins again

dolomite calcitization and cement zonation related to uplift of the raisby formation zechstein carbonate northeast england abstract the raisby formation is the basal zechstein carbonate of northeast england it has undergone a complex diagenetic history during burial including multiphase dolomitization and replacement by sulphates upon uplift meteoric derived fluids have dissolved this replacive sulphate and precipitated calcite cements in the resultant porosity study of these cements by cathodoluminescence and trace element geochemistry shows that they are zoned and different cathodoluminescence zones correlate well with iron and manganese geochemical changes demonstrating a gradual increase in oxygenation of the precipitating fluids through time major diagenetic processes during cement growth include precipitation of anhydrite fluorite and barite calcitization of dolomite and internal sedimentation relating these processes to cement zonation allows this complex diagenesis to be explained in terms of uplift under the influence of meteoric derived groundwaters of constantly changing geochemical and electrochemical characteristics

mount etna dense array local earthquake p and s tomography and implications for volcanic plumbing inversion for the three dimensional velocity structure of mount etna is performed with a data set of arrival times of p and s waves of local earthquakes from temporary dense arrays of three component seismographs a high v p body revealed by the original tomography without nearby stations is confirmed and its image is sharpened using new velocity constraints provided by refraction data synthetic tests of v p and v p v s and comparison with an independent artificial source tomography with a fundamentally different geometry consistently calibrate the significance threshold of the resolution indicators the trustworthy part of the image shows a high v p body centered under the southern part of valle del bove above the 6 km below sea level deep basement which extends towards sea level and may be rooted in or through the crust it has a large contrast of over 1 km s with the surrounding sediments and sharp lateral limits and can thus be regarded as made of intrusive material of magmatic origin the massive high v p body is heterogeneous in v p v s the regions inside it where v s is relatively low can then be suspected of containing a proportion of melt or be fractured and act as pressure links or transport zones such features may be structurally linked and appear to be activated in eruptive phenomena by taking into account the heterogeneities in structure and physical state retrieved by seismic tomography a succession of seismic events deformational episodes and geochemical variation in lavas can be discussed with respect to the well observed eruptions

imaging the shallow crust with teleseismic receiver functions summary teleseismic receiver functions rfs represent an estimate of the site response to incoming seismic energy this technique has long been a staple of the global earthquake community as rfs are sensitive to impedance contrasts associated with major discontinuities in the crust and upper mantle however there is substantial debate in the community concerning the lateral and vertical resolution limits possible using these methods due to limitations resulting from ambient noise and non uniform spatial sampling of finite frequency wave kernels here we take advantage of data from the labarge passive seismic experiment to examine these questions in more detail we find 1 that rfs can provide a robust image of the near surface 5 km structure 2 that vertical resolution may exceed 500 m and 3 that our results compare favourably to nearby wells these results indicate that rf analysis can provide high resolution images of the shallow crust which has potential value for hydrocarbon exploration

moist convection as an energy source for the large scale motions in jupiter s atmosphere jupiter s dominant large scale weather patterns dimensions 10 000 km are zonal jets and long lived ovals the jets have been flowing east and west at constant speeds of up to 180 m s 1 for over 100 years these jets receive energy from small scale eddies which pump eastward momentum into the eastward jets and westward momentum into the westward jets this momentum transfer was predicted by numerical models before it was observed on jupiter the large ovals roll between the jets in an anticyclonic direction clockwise in the northern hemisphere and counterclockwise in the southern hemisphere where they regularly assimilate small anticyclonic eddies but from where the eddies receive their energy has been an open question here we argue that the eddies which ultimately drive both the jets and the ovals receive their energy from moist convection this hypothesis is consistent with observations of jovian lightning which is an indicator of moist convection it also explains the anticyclonic rotation and poleward drift of the eddies and suggests patterns of upwelling and downwelling that resemble the patterns of large scale axisymmetric overturning in the earth s atmosphere

thermal structure and composition of jupiter s great red spot from high resolution thermal imaging abstract thermal ir imaging from space borne and ground based observatories was used to investigate the temperature composition and aerosol structure of jupiter s great red spot grs and its temporal variability between 1995 and 2008 an elliptical warm core extending over 8 of longitude and 3 of latitude was observed within the cold anticyclonic vortex at 21 s the warm airmass is co located with the deepest red coloration of the grs interior the maximum contrast between the core and the coldest regions of the grs was 3 0 3 5 k in the north south direction at 400 mbar atmospheric pressure although the warmer temperatures are present throughout the 150 500 mbar range the resulting thermal gradients cause counter rotating flow in the grs center to decay with altitude into the lower stratosphere the elliptical warm airmass was too small to be observed in irtf imaging prior to 2006 but was present throughout the 2006 2008 period in vlt subaru and gemini imaging spatially resolved maps of mid ir tropospheric aerosol opacity revealed a well defined lane of depleted aerosols around the grs periphery and a correlation with visibly dark jovian clouds and bright 4 8 m emission ammonia showed a similar but broader ring of depletion encircling the grs this narrow lane of subsidence keeps red aerosols physically separate from white aerosols external to the grs the visibility of the 4 8 m bright periphery varies with the mid ir aerosol opacity of the upper troposphere compositional maps of ammonia phosphine and para h 2 within the grs interior all exhibit north south asymmetries with evidence for higher concentrations north of the warm central core and the strongest depletions in a symmetric arc near the southern periphery small scale enhancements in temperature nh 3 and aerosol opacity associated with localized convection are observed within the generally warm and aerosol free south equatorial belt seb northwest of the grs the extent of 4 8 m emission from the seb varied as a part of the 2007 global upheaval though changes during this period were restricted to pressures greater than 500 mbar finally a region of enhanced temperatures extended southwest of the grs during the survey restricted to the 100 400 mbar range and with no counterpart in visible imaging or compositional mapping the warm airmass was perturbed by frequent encounters with the cold airmass of oval ba but no internal thermal or compositional effects were noted in either vortex during the close encounters

low limit of mn2 activated cathodoluminescence of calcite state of the art in the literature the lower limit for mn2 activated cathodoluminescence cl of calcite is variously reputed to over a very wide range of values above 10 ppm mn our spectroscopic investigations of the cl response in natural calcite reveal that below 10 ppm manganese content mn2 activation is also present using the quantitative high resolution spectral analysis of cl qhrs cl an activation by mn2 in the range of 700 ppb is proved which cannot be determined visually so if not quenched the minimum mn2 content for mn2 activation is one atom in the irradiated calcite crystal lattice volume as the intrinsic background blue luminescence is used to determine non altered biogenic calcite the limit of mn2 activation plays an important role in the interpretation of diagenetic processes our results of spectroscopic analyses require a revision of current opinions about the diagenesis of calcite as revealed by cl investigation

epic simulations of bright companions to neptune s great dark spots abstract we present a three dimensional model of the bright companion clouds associated with neptune s great dark spots gdss our results support the hypothesis that the bright companions of the southern hemisphere gds discovered in 1989 and of the northern hemisphere gds discovered in 1994 are methane clouds that form at or just below the tropopause and that they are caused by lifting in a manner analogous to the formation of orographic clouds we vary the vertical position of the gds and find that the companion cloud is a robust feature except when the anticyclone itself does not survive when a gds is started with its top in the stratosphere it drifts much too rapidly toward the equator and quickly disperses on the other hand if its top is well below the tropopause there is a tendency for the companion clouds to be too large hence the top of a gds is probably at the tropopause along an open streamline that threads a bright companion the typical pressure and temperature drops are about 3 mb and 1k respectively corresponding to a lift of about half a kilometer or 4 of the pressure scale height and the relative horizontal wind speed is about 45 m s 1 eastward through the cloud

jupiter s unearthly jets a new turbulent model exhibiting statistical steadiness without large scale dissipation abstracta longstanding mystery about jupiter has been the straightness and steadiness of its weather layer jets quite unlike terrestrial strong jets with their characteristic unsteadiness and long wavelength meandering the problem is addressed in two steps the first is to take seriously the classic dowling ingersoll di 1 layer scenario and its supporting observational evidence pointing toward deep massive zonally symmetric zonal jets in the underlying dry convective layer the second is to improve the realism of the model stochastic forcing used to represent the effects of jupiter s moist convection as far as possible within the 1 layer dynamics of the di scenario the real moist convection should be strongest in the belts where the interface to the deep flow is highest and coldest and should generate cyclones as well as anticyclones with the anticyclones systematically stronger the new model forcing reflects these insights also it acts quasi frictionally on large scales to produce statisti

earthworms produce granules of intricately zoned calcite earthworms of the family lumbricidae which includes many common species produce and secrete up to millimeter sized calcite granules and the intricate fine scale zoning of their constituent crystals is unique for a biomineral granule calcite is produced by crystallization of amorphous calcium carbonate acc that initially precipitates within the earthworm calciferous glands then forms protogranules by accretion on quartz grain cores crystallization of acc is mediated by migrating fluid films and is largely complete within 24 h of acc production and before granules leave the earthworm variations in the density of defects formed as a byproduct of trace element incorporation during calcite crystal growth have generated zoning that can be resolved by cathodoluminescence imaging at ultraviolet to blue wavelengths and using the novel technique of scanning electron microscope charge contrast imaging mapping of calcite crystal orientations by electron backscatter diffraction reveals an approximate radial fabric to the granules that reflects crystal growth from internal nucleation sites toward their margins the survival within granules of acc inclusions for months after they enter soils indicates that they crystallize only within the earthworm and in the presence of fluids containing biochemical catalysts the earthworm probably promotes crystallization of acc in order to prevent remobilization of the calcium carbonate by dissolution calcite granules vividly illustrate the role of transient precursors in biomineralization but the underlying question of why earthworms produce granules in volumes sufficient to have a measurable impact on soil carbon cycling remains to be answered

jupiter s great red spot fine scale matches of model vorticity patterns to prevailing cloud patterns abstract we report on a set of six new matches between fine scale features in the vorticity field of a three dimensional 3d primitive equation finite difference model of jupiter s great red spot that includes no clouds or cloud physics and quasi permanent structures in reflected visible band images of the clouds these add to similar success by cho et al cho j de la torre juarez m ingersoll a p dritschel d g 2001 j geophys res 106 5099 5106 who earlier captured four characteristic features of the grs also reproduced here using a 3d quasi geostrophic cloud free contour dynamics model in that study and this the key enabling model attribute is sufficient horizontal resolution rather than the moist convective and cloud microphysics processes often required to match the patterns of clouds in terrestrial hurricanes the only significant feature that these dry models do not capture is the episodic moist convective plumes seen in the northwest quadrant adjacent to the grs we initialize with jupiter s averaged zonal winds plus an approximately balanced smooth 3d ellipsoidal anticyclone the threshold horizontal grid resolution to obtain the fine scale matches is approximately y ld 0 15 where y 300 km is the meridional grid spacing and ld 2000 km the rossby deformation length for models with this or finer horizontal resolution the best correspondence with observations is reached after about six vortex turnaround times from initialization 30 earth days but good facsimiles of nearly all the studied features appear after only 1 5 turnaround times 7 8 days we conclude that in images of jupiter it is not accurate to associate clouds with upward motion since these dry models reproduce the observed cloud patterns without this association and indeed the synoptic scale vertical motions in the model as well as those deduced from observations do not at all correspond to the observed cloud patterns instead jupiter s cloud top patterns indicate the effects of local shear in the manner of passive tracer fields as a corollary the water clouds on jupiter which lie unseen below its visible clouds are the only ones on the planet likely to correlate with upwelling in the manner that clouds do on earth the next step is to extend studies such as this past the reflected visible band for example to include the grs s 5 m emission bright collar which may require the inclusion of cloud physics to enable the successful simulation of large voids

merging circulations on jupiter observed differences between cyclonic and anticyclonic mergers abstract the dynamics of mergers of large circulations in jupiter s atmosphere may permit different models of the atmosphere to be tested we report well resolved observations of such events at visible wavelengths three anticyclonic and three cyclonic events a merger of anticyclonic white ovals in the south south temperate domain 2002 march is compared with the previously reported merger of ovals be and fa in the south temperate domain 2000 march in each case the two similar sized ovals converged rapidly once they were separated by less than the sum of their diameters they orbited around each other anticyclonically during the merger the merged oval initially had the same rapid drift as the western parent and in an unexpected similarity a cyclonic oval emerged westward from the point of merger evidence suggests that a merger of smaller ovals in the north north temperate domain 2002 february had similar dynamics in contrast mergers of cyclonic ovals in the north equatorial belt barges 2001 november 2005 may proceeded in a different manner the two parent barges showed no consistent acceleration towards each other as they converged on contact there was no obvious sign of mutual circulation and the low albedo regions had almost passed each other before they finally merged and the resulting barge had a drift rate intermediate between the two parents and a length that was greater than either parent again a third such event involving a smaller barge 2002 december showed many of the same characteristics these observations define different dynamical behaviour during anticyclonic and cyclonic mergers

how to overcome imaging problems associated with carbonate minerals on sem based cathodoluminescence systems on sem based cathodoluminescence systems scanned cl methods are needed to overcome image quality problems caused by persistent luminescence of carbonate minerals an effective solution to the persistence problem is to acquire images using only the shorter wavelengths most easily done by using a broadband short wavelength uv blue range filter the filter used provides 80 to 90 transmissivity in the range of 385 to 495 nm and some transmissivity as low as 350 nm the filter allows transmission of the relatively nonpersistent uv violet luminescence present in most carbonates in the range of 350 to 425 nm but blocks the common orange red wavelength luminescence found in carbonates the lack of imaging problems in subsequent images shows that persistent luminescence in carbonates is primarily in the orange red wavelengths cathodoluminescence images produced using a short wavelength filter are comparable in detail to those obtained from conventional light microscope based cathodoluminescence systems in almost all examples features visible in the orange red wavelengths show corresponding variations in luminescence in the shorter wavelengths

seismic heterogeneity and small scale convection in the southern california upper mantle we invert traveltime residuals of teleseismic p and s phases for 3 d perturbations in vp vs and vp vs structures in the southern california upper mantle the tomographic inversion uses frequency dependent 3 d sensitivity kernels to interpret traveltime residuals measured in multiple frequency bands and recent advances in regional crustal thickness and velocity models to better isolate the mantle component of traveltime residuals in addition to separate vp and vs tomography we jointly invert the p and s data sets for vp vs perturbations by imposing a smoothness constraint on the lnvs lnvp field the regional upper mantle is very heterogeneous with the greatest amplitude of velocity and vp vs perturbations in the upper 200 km and mantle structures that correlate spatially with the major physiographic provinces of southern california our imaging improves the resolution of the geometry and amplitude of these features in addition to the major structures imaged and discussed in previous papers we find a large high velocity anomaly at depths between 340 and 500 km beneath the borderland transverse ranges and northern peninsular ranges this anomaly is separate from the well known uppermost mantle transverse ranges anomaly which extends no deeper than 175 200 km the strongest low velocity high vp vs anomaly is found beneath and west of the salton trough and is attributed to relatively high partial melt in the asthenosphere as a result of lithospheric thinning the magnitudes of vp vs and vp vs perturbations and knowledge of regional 1 d velocity and attenuation lead us to conclude that the asthenosphere contains up to 1 partial melt extending to depths as great as 150 200 km

dynamics and interaction between a large scale vortex and the great red spot in jupiter abstract a unique large scale vortex the white tropical oval wtro was first observed in the south tropical zone of jupiter at the latitude of the great red spot grs in 1983 its origin is probably related to a period of intense formation of eddies in the southern edge of the south equatorial belt at latitude 20 the wtro survived many changes in the cloud structure of the south equatorial belt however in mid may 1997 the wtro was entrained by the grs peripheral flow because of its large size the wtro did not circulate around the grs s collar as other smaller eddies do but instead after travelling one quarter of the grs ellipse it was expelled and finally destroyed when it became advected by the grs s surrounding zonal flow the grs responded to this interaction by exhibiting small latitude and longitude displacements 3 the main properties of the wtro based on our prolonged imaging program 14 years were the following average latitude graphic 21 5 extremes 20 5 to 23 5 zonal velocity relative to system iii 4 m s extremes 2 to 7 m s major axis east west 8100 km minor axis north south 5100 km its average zonal velocity showed a significant departure relative to the ambient flow velocity of 35 ms 1 the tangential velocity along the southern flank of the vortex was 8 to 40 ms 1 giving an area averaged anticyclonic vorticity 1 35 10 5 s 1 this value is close to that of the ambient flow indicating that the wtro was a weak vortex most of the time the wtro showed a white oval form surrounded by a darker ring although during some months in 1993 the southern part turned redder with a color similar to that of the grs the relative spectral reflectivity from 230 nm to 2 3 m suggests that the wtro had a cloud structure similar to other well known jovian anticyclones

moist convection and the 2010 2011 revival of jupiter s south equatorial belt fletcher was supported by a royal society research fellowship at the university of leicester giles was supported by a royal society research grant at the university of oxford the uk authors acknowledge the support of the science and technology facilities council stfc a portion of this work was performed by orton and payne at the jet propulsion laboratory california institute of technology under a contract with nasa this research used the alice high performance computing facility at the university of leicester we are extremely grateful for the combined efforts of the numerous amateur observers including those listed in the figure captions for sharing their data and for the jupos software developed by grischa hahn and hans jorg mettig to reproject the visible light data this investigation was partially based on thermal infrared observations acquired at i the eso very large telescope paranal ut3 melipal observatory using directors discretionary time program id 286 c 5009 and regular service time program id 087 c 0024 ii the subaru telescope which is 27 operated by the national astronomical observatory of japan program id o11154 iii nasa s infrared telescope facility which is operated by the university of hawaii under contract nnh14ck55b with the national aeronautics and space administration program ids 2010b010 2011a010 2011b027 and iv observations obtained at the gemini observatory program ids gn 2010b dd 3 gs 2010b q 8 and gs 2011aq 11 which is operated by the association of universities for research in astronomy inc under a cooperative agreement with the nsf on behalf of the gemini partnership the national science foundation united states the national research council canada conicyt chile ministerio de ciencia tecnolog ia e innovacion productiva argentina and ministerio da ci encia tecnologia e inovac ao brazil we wish to recognise and acknowledge the very significant cultural role and reverence that the summit of mauna kea has always had within the indigenous hawaiian community we are most fortunate to have the opportunity to conduct observations from this mountain

aragonite in the murray cm2 carbonaceous chondrite implications for parent body compaction and aqueous alteration the matrix of the cm2 carbonaceous chondrite murray contains rare micrometer sized prismatic crystals of aragonite that formed during late stage parent body aqueous alteration the aragonite was identified by x ray microanalysis coupled with electron backscatter diffraction ebsd tem selected area electron diffraction and cathodoluminescence spectroscopy the sixteen crystals found all occur within loose and elongate submillimeter sized clusters and one cluster is present in each of the two thin sections studied orientation determinations using ebsd show that the c axes of aragonite crystals within each cluster lie roughly in a plane itself aligned approximately parallel to the long axis of the host cluster aragonite is inferred to have crystallized after calcite but before completion of static impact related compaction the clusters developed by growth of aragonite within films of aqueous fluids that had a relatively high mg ca ratio these fluids were focused within zones of high porosity and permeability along a weak compactional fabric in the matrix and this fabric is also likely to have influenced the orientations of aragonite crystals as they grew these results suggest that aragonite probably occurs in most of those carbonaceous chondrites that have undergone moderate degrees of parent body aqueous alteration and may provide further insights into the evolution of pore fluid compositions and volumes and the chronology of asteroidal evolution

imaging of cathodoluminescence zoning in calcite by scanning electron microscopy and hyperspectral mapping abstract imaging of cathodoluminescence cl emission from carbonate minerals by scanning electron microscopy sem is problematic owing to the slow rate at which cl decays from each point as the electron beam is scanned over an area the phenomenon of phosphorescence using sem cl and a newly developed electron probe based technique of hyperspectral mapping we have evaluated methods that have been proposed to overcome phosphorescence with the dwell time technique the duration of time that the electron beam is static is increased such that cl emission from a given point makes a negligible contribution to the total signal from subsequent points the dwell time required to form sharp sem cl images of calcite that has a high intensity of luminescence at orange wavelengths is equal to or greater than 6 4 milliseconds whereas calcite that luminesces predominantly at ultraviolet to blue wavelengths can be imaged using submillisecond dwell times by using longer dwell times 1000 ms cl and x ray spectra can also be acquired from each point to form hyperspectral maps the limited wavelength imaging technique employs optical filters to excise slowly decaying long wavelength emission so that the image is formed only using the more rapidly decaying ultraviolet to blue wavelengths allowing shorter dwell times to be used both techniques have some disadvantages the main drawback of the dwell time technique is the long period of time required to acquire high resolution images whereas the success of limited wavelength imaging may depend on the sensitivity of the cl detector being used cl images and emission spectra acquired by hyperspectral mapping also show that there is a nonlinear relationship between luminescence intensity variations at ultraviolet to blue wavelengths and intensity variations at orange wavelengths indicating that short wavelength emission is an imperfect proxy for zoning at longer wavelengths additionally we have been unable to identify the controls on spatial variations in the intensity of ultraviolet to blue luminescence although our data discount fe2 concentrations as being the sole determinant by using hyperspectral mapping in combination with electron probe microanalysis to obtain cl and x ray spectra from the same micrometer sized volume of a material it is now possible to understand and quantify the controls on activation and quenching of cl in calcite and other minerals such as apatite and zircon

combined cathodoluminescence hyperspectral imaging and wavelength dispersive x ray analysis of minerals the usefulness of cathodoluminescence cl in mineralogy and petrology is largely due to its high sensitivity to variations in the chemical compositions of minerals difficulty in interpretation of cl images however often limits their use beyond the identification of growth zones which are then analyzed using other more readily quantifiable techniques the use of scanning electron microscopy sem cl in hyperspectral imaging mode combined with simultaneously acquired x ray composition mapping extends the technique by allowing the separation of spectral features and their correlation with elemental composition in this paper we describe the use of such measurements in conjunction with multivariate statistical analysis to automatically identify and characterize zones in calcite and zircon we demonstrate that this novel combination of techniques significantly increases the effectiveness of cl as a diagnostic tool for earth science applications

cassini imaging of saturn southern hemisphere winds and vortices high resolution images of saturn s southern hemisphere acquired by the cassini imaging science subsystem between february and october 2004 are used to create maps of cloud morphology at several wavelengths to derive zonal winds and to characterize the distribution frequency size morphology color behavior and lifetime of vortices nonequatorial wind measurements display only minor differences from those collected since 1981 and reveal a strong prograde flow near the pole the region just southward of the velocity minimum at 40 7 s is especially active containing numerous vortices some generated in the proximity of convective storms the two eastward jets nearest the pole display periodicity in their longitudinal structure but no direct analogs to the northern hemisphere s polar hexagon or ribbon waves were observed characteristics of winds and vortices are compared with those of saturn s northern hemisphere and jupiter s atmosphere

on the interaction of jupiter s great red spot and zonal jet streams abstract in this paper jupiter s great red spot grs is used to determine properties of the jovian atmosphere that cannot otherwise be found these properties include the potential vorticity of the grs and its neighboring jet streams the shear imposed on the grs by the jet streams and the vertical entropy gradient i e rossby deformation radius the cloud cover of the grs which is often used to define the grs s area and aspect ratio is found to differ significantly from the region of the grs s potential vorticity anomaly the westward going jet stream to the north of the grs and the eastward going jet stream to its south are each found to have a large potential vorticity jump the jumps have opposite signs and as a consequence of their interaction with the grs the shear imposed on the grs is reduced the aspect ratio of the grs s potential vorticity anomaly depends on the ratio of the imposed shear to the strength of the anomaly the east west to north south aspect ratio is found to be 2 1

cathodoluminescence in calcite cements new insights on pb and zn sensitizing mn activation and fe quenching at low trace element concentrations abstract the role of pb and zn as sensitizers of cathodolumines cl in sedimentary carbonates is still speculative as is the relationship between mn fe and cl intensity at low concentrations of mn and fe we address these questions using calcite cements from the lower oligocene suwannee formation of florida which have mean mn pb zn and fe concentrations less than 45 ppm only a small fraction of these cements exhibit visible cl but when present the luminescence is orange to reddish orange trace element contents were measured using a synchrotron x ray fluorescence microprobe and cl intensity was approximated by spot metered photomicrograph exposure times based on mn and fe contents four cement populations can be defined group i is luminescent calcite with mn 25 ppm and molar mn fe 1 8 group ii contains both luminescent and nonluminescent cements all with mn 25 ppm molar mn fe 25 ppm molar mn fe 100 ppm group iv is nonluminescent calcite with mn 25 ppm and variable fe these groupings and statistical analyses of the data mann whitney tests and factor analyses confirm that 25 ppm mn is necessary to initiate visible cl and that mn is the sole control on cl intensity when mn and fe contents are very low 100 ppm the data also establish 100 ppm fe as a new minimum for the quenching of cl when mn is below 200 ppm there is no evidence in our data that pb or zn concentrations in tens of parts per million either activate or sensitize cl the mann whitney test shows that there is no statistical evidence at the 95 confidence level to indicate that luminescent and nonluminescent cements reflect different populations of pb and zn except for group ii cements that have more pb in nonluminescent cements than in otherwise chemically equivalent luminescent cements factor analysis shows that cl intensity in all luminescent cements is unrelated to pb or zn concentrations given that pb or zn sensitizing is lacking in low mn calcites like the suwannee cements it is hard to imagine how these elements could play a significant role in calcites containing even more mn as is typical of most sedimentary carbonates

charge contrast imaging cci revealing enhanced diagenetic features of a coquina limestone abstract charge contrast imaging cci is a low vacuum scanning electron microscope lv sem technique that can be induced through partial surface charge suppression of uncoated nonconductive samples imaged with a suitable detector such as a gaseous secondary electron detector gsed the technique commonly produces results similar in style to that of sem cathodoluminescence sem cl providing information on zoning twinning annealed fractures and subtle chemical changes the current work outlines an example from a brazilian lower cretaceous coquina limestone in which both optical and sem cl imaging produces a limited response from much of the sample backscattered electron bse imaging typically suggests only a hint of the cement present whereas cci clearly displays a rich and varied cement stratigraphy the earliest cement displays strong cci but appears mainly dark under cl imaging conditions sem cl and optical cl later stage manganese enriched carbonate cement displays luminescence with both optical and sem cl as well as a cci response therefore cci can provide additional information on cement zonation in an area where cl cannot

long term tracking of circumpolar cyclones on jupiter from polar observations with junocam abstract we use observations from the junocam instrument on the juno spacecraft to map the polar regions of jupiter between 2016 and 2018 these polar maps track the long term evolution of the pentagonal and octagonal structures of circumpolar cyclones cpcs the south polar pentagonal and north polar octagonal arrangements of the cpcs have remained largely stable over the last 2 years of observation the morphologies of individual cyclones also remain largely stable for 1 2 years although some changes are observed so that the location of each cpc is uniquely identifiable at both north and south poles individual cyclones move around the center to a limited extent and there is a gap of variable width between one pair of south polar cpcs measurements at consecutive closest approaches perijoves 53 days apart show small movements of individual cyclones both eastward and westward however the south polar cpcs have a long term systematic westward drift rate of 1 5 0 2 per orbit or 0 040 0 005 m s whereas north polar cpcs do not show a consistent drift in longitude around the perimeter of the southern pentagon we detect no rapid jet in short term animations and we provide evidence that anticyclonic white ovals may have a range of longitudinal drifts between 44 and 15 per orbit 1 8 to 0 7 m s measurement of the angular velocities within the cyclones shows increasing angular velocity with decreasing radius except in the inner bright cloud deck of one class of northern cpcs which are inferred to have smaller or even negative angular velocities very near the center tangential wind velocities within the cyclones range up to 100 m s and even 100 m s in the southern polar cyclone and are maximal between radii of 900 1600 km overall we find that the behavior of the polar cyclones constellations compares well to vortex crystal theory even though the theory does not include anticyclonic vorticity

origin of jupiter s cloud level zonal winds remains a puzzle even after juno how far jupiter s cloud level zonal winds penetrate into its interior a question related to the origin of the winds has long been a major puzzle about jupiter there exist two different views the shallow scenario in which the cloud level winds are confined within the thin weather layer at cloud top and the deep scenario in which the cloud level winds manifest thermal convection in the deep interior we interpret using two different models corresponding to the two scenarios the high precision measurements of jupiter s equatorially antisymmetric gravitational field by the juno spacecraft we demonstrate based on the thermal gravitational wind equation that both the shallow and deep cloud level winds models are capable of explaining the measured odd gravitational coefficients within the measured uncertainties reflecting the nonunique nature of the gravity inverse problem we conclude that the high precision juno gravity measurements cannot provide an answer to the long standing question about the origin of jupiter s cloud level zonal winds

atmospheric waves and dynamics beneath jupiter s clouds from radio wavelength observations abstract we observed jupiter at wavelengths near 2 cm with the karl g jansky very large array vla in february 2015 these frequencies are mostly sensitive to variations in ammonia abundance and probe between 0 5 2 0 bars of pressure in jupiter s atmosphere within and below the visible cloud deck which has its base near 0 7 bars the resultant observed data were projected into a cylindrical map of the planet with spatial resolution of 1500 km at the equator we have examined the data for atmospheric waves and observed a prominent bright belt of radio hotspot features near 10 n likely connected to the same equatorial wave associated with the 5 m hotspots we conducted a passive tracer power spectral wave analysis for the entire map and latitude regions corresponding to eastward and westward jets and compare our results to previous studies the power spectra analysis revealed that the atmosphere sampled in our observation excluding the neb region is in a 2 d turbulent regime and its dynamics are predominately governed by the shallow water equations the great red spot grs is also very prominent and has a noticeable meridional asymmetry and we compare it and nearby storms with optical images we find that the meridional radio profile has a global north south hemisphere distinction and find correlations of it to optical intensity banding and to shear zones of the zonal wind profile over select regions of latitude amateur optical images taken before and after our observation complemented the radio wavelength map to investigate dynamics of the equatorial region in jupiter s atmosphere we find that two radio hotspots at 2 cm are well correlated with optical plumes in the neb additionally revealing they are not the same 5 m hotspot features correlated with optical dark patches between adjacent plumes this analysis exploits the vla s upgraded sensitivity and explores the opportunities now possible when studying gas giants especially atmospheric dynamics of layers beneath upper level clouds

hst imaging of atmospheric phenomena created by the impact of comet shoemaker levy 9 hubble space telescope hst images reveal major atmospheric changes created by the collision of comet shoemaker levy 9 with jupiter plumes rose to 3000 kilometers with ejection velocities on the order of 10 kilometers second 1 some plumes were visible in the shadow of jupiter before rising into sunlight during some impacts the incoming bolide may have been detected impact times were on average about 8 minutes later than predicted atmospheric waves were seen with a wave front speed of 454 20 meters second 1 the hst images reveal impact site evolution and record the overall change in jupiter s appearance as a result of the bombardment