vertical wind shear on jupiter from cassini images 1 multifilter images of jupiter acquired by the cassini imaging science subsystem iss are used to derive zonal winds at altitudes above and below the visible cloud deck small features unique to the ultraviolet images of iss are tracked to get the systematic high altitude zonal winds comparison between the zonal winds from ultraviolet images and the vertical profile of zonal winds from the cassini composite infrared spectrometer cirs shows that the zonal winds from the ultraviolet images are from a pressure level that is 0 2 scale heights higher than the pressure level of the zonal winds from continuum band images deeper zonal winds at different latitudes of the equatorial region are measured by tracking cloud features observed within hot spots on continuum band images the deeper zonal winds in this study extend the measurement of the galileo probe to different latitudes of the equatorial region comparison between the galileo probe and this study suggests that these fast moving clouds within hot spots are deeper than 3 bars and are therefore probably water clouds

winds of neptune voyager observations of cloud motions high temporal and spatial resolution images acquired from voyager cameras have been used to measure cloud motions to improve the meridional profile of the zonal mean circulation on neptune a wide range of atmospheric periods between 12 and 21 hours is revealed by the average cloud motions consistent with the previous observations new observations have expanded latitudinal coverage improved the determination of streak motions especially near 30 n and added statistical weight to latitudes already covered by previous measurements both new and earlier observations have been subjected to quality control procedures to reduce dispersion caused by erroneous observations the resulting data set emphasizes short time intervals to maximize target recognition most reliable cloud targets last less than one neptune rotation many only a fraction of it a broad equatorial retrograde jet extends from approximately 50 s to at least 45 n the northernmost latitude at which discrete cloud features have been seen a relatively narrow prograde jet of at least 300 m s 1 is found near 70 s the wind observations have a high degree of variability some of which is due to variability of motions but at many latitudes it reflects observation errors arising from rapid evolution of neptune s clouds a bias observed in the measured meridional component is most likely due to a small discrepancy between the true rotation pole of neptune and the pole position used in the data reduction zonal motions and morphology suggest the global circulation to be symmetric about the equator

the galileo probe doppler wind experiment measurement of the deep zonal winds on jupiter during its descent into the upper atmosphere of jupiter the galileo probe transmitted data to the orbiter for 57 5 min accurate measurements of the probe radio frequency driven by an ultrastable oscillator allowed an accurate time history of the probe motions to be reconstructed removal from the probe radio frequency profile of known doppler contributions including the orbiter trajectory the probe descent velocity and the rotation of jupiter left a measurable frequency residual due to jupiter s zonal winds and microdynamical motion of the probe from spin swing under the parachute atmospheric turbulence and aerodynamic buffeting from the assumption of the dominance of the zonal horizontal winds the frequency residuals were inverted and resulted in the first in situ measurements of the vertical profile of jupiter s deep zonal winds a number of error sources with the capability of corrupting the frequency measurements or the interpretation of the frequency residuals were considered using reasonable assumptions and calibrations from prelaunch and in flight testing it is found that beneath the cloud tops about 700 mbar the winds are prograde and rise rapidly to 170 m s at 4 bars beyond 4 bars to the depth at which the link with the probe was lost nearly 21 bars the winds remain constant and strong corrections for the high temperatures encountered by the probe have recently been completed and provide no evidence of diminishing or strengthening of the zonal wind profile in the deeper regions explored by the galileo probe

planetary waves in jupiter s equatorial atmosphere abstract voyager infrared radio occultation and imaging measurements provide a variety of observational evidence and constraints for planetary scale waves latitudinally trapped within jupiter s equatorial jet the visually prominent plumes encircling the planet at 8 deg north latitude show a longitudinal organization of wavenumber n 11 13 an apparently solitary plume also appears at about 8 deg south along the with other smaller periodic cloud features deviations in cloud tracked driff speed including differences in mean values to the north and south of the equator in excess of 25 m sec 1 may be crudely indicative of the magnitude of the associated wave phase speeds radio occultation retrievals of the temperature profiles at two equatorial longitudes show harmonic variation consistent with the stratospheric propagation of two components with vertical wavelengths of approximately 3 and 0 5 scale heights these observations may be consistently interpreted in terms of specific classes of equatorially trapped wave modes the gravest equatorial rossby mode with an equivalent depth of h 2 4 km with a stratospheric wavelength of 3 4 scale heights represents the most consistent interpretation of the plumes the inferred vetical eigenmode could be ducted by a deep statically stable layer possibly imposed by a roughly solar abundant water cloud depending upon the actual details of the moist convection an estimate of the relative growth rates for the near neutral forcing of rossby modes of the inferred equivalent depth implies a maximum for zonal wavenumber 11 the solitary plume feature to the south of the equator may be interpreted as a wavenumber 1 rossby mode with the same vertical scale possibly forced by the interaction between the equatorial jet and the great red spot smaller visual features may correspond to inertia gravity modes with vertical wavelengths comparable to the small harmonic of the occultation profiles galileo orbiter and probe observations will provide an essential test of the wave analysis and substantially enhance its diagnostic utility

propagation characteristics of extratropical planetary waves observed in the atsr global sea surface temperature record this paper examines the characteristics of planetary wave signatures that have been found in the along track scanning radiometer averaged sea surface temperature asst record for 1991 1996 longitude time plots for every latitude between 5 and 50 north and south reveal westward propagating wave like patterns at many locations whose speed decreases with latitude like baroclinic rossby waves a two dimensional radon transform method is used to measure the wave speed and its variation with location and time which broadly matches the rossby wave speeds predicted by the most recent theory and those measured by topex altimetry although there are some discrepancies at low latitudes the thermally detected speeds are slower than expected a possible consequence of sampling limitations wave signatures are clearest between 25 and 40 s where the meridional temperature gradient is strongest here observed speeds are 20 30 greater than theoretical predictions planetary wave speed varies considerably with longitude in general it increases toward the west of ocean basins and distinct differences between ocean basins are evident the propagation characteristics of the waves appear to change abruptly at locations consistent with latitudinal variations in seafloor bathymetry particularly midocean ridges in addition eastward propagating signatures are found in the southern ocean the results demonstrate the value of the asst data set as a tool for studying basin scale wave processes as a complement to the use of altimetry by observing the thermal signature of rossby waves the method has the potential to clarify their influence on air sea interaction processes and to contribute to climate modeling studies

characterisation and engineering properties of tectonically undisturbed but lithologically varied sedimentary rock masses tectonically undisturbed sedimentary rocks deposited in a quiescent shallow marine environment often include a sequence of strata that may present significant lithological variety at the scale of an engineering structure such rock masses exhibit engineering properties that are significantly different from tectonically disturbed rock masses of similar composition for example molasse consists of a series of tectonically undisturbed sediments of sandstones conglomerates siltstones and marls produced by the erosion of mountain ranges after the final phase of an orogeny they behave quite differently from flysch which has the same composition but which was tectonically disturbed during the orogeny the molasses behave as continuous rock masses when they are confined at depth and the bedding planes do not appear as clearly defined discontinuity surfaces close to the surface the layering of the formations is discernible and only then similarities may exist with the structure of some types of flysch therefore extreme care is necessary in the use of geotechnical classification systems for the selection of design parameters in order to avoid penalizing the rock mass unnecessarily a discussion on the use of the geological strength index gsi for the characterisation of such rock masses is presented two gsi charts are proposed for estimating the mechanical properties of these masses one mainly for tunnels and the second for surface excavations an example is given to illustrate the process of tunnel design in molassic rocks

an ensemble kalman filter for the time dependent analysis of the geomagnetic field we present the application of the ensemble kalman filter to a three dimensional convection driven model of the geodynamo our implementation rests on a suitably modified version of the parallel data assimilation framework of nerger and hiller 2013 we resort to closed loop experiments for validation purposes using a dynamo model of intermediate resolution observations for these experiments consist of spectral coefficients describing the surface poloidal magnetic field with arbitrary truncation our synthetic tests demonstrate the efficacy and adaptivity of the method provided the ensemble comprises o 500 members in which case the typical spin up time we find for our system is o 1000 years in case of a poor resolution of the observations we find that the knowledge of the full covariance matrix describing the uncertainty affecting the spectral coefficients as opposed to its sole diagonal results in a much better estimate of the internal structure of the dynamo

motions in jovian hot spot plume regions using voyager images abstract we have measured the motions and wind velocity vectors in six jovian hot spot plume areas latitudes 0 to 12 using high resolution voyager 1 and 2 images separated by one jovian rotation 10 hr rapid changes in cloud forms take place in a few hours at scales from 100 to 2000 km no large scale organized motions e g diagonal convergence along the plume tails toward hot spots or circulation patterns such as those recently reported using galileo images separated by 1 hr have been found we show that particle evaporation and cloud element mixing in the upper ammonia cloud could be fast enough to dissipate the small cloud elements such as those used as tracers by the galileo ssi team in less than 10 hr

reconstructing holocene geomagnetic field variation new methods models and implications reconstructions of the holocene geomagnetic field and how it varies on millennial timescales are important for understanding processes in the core but may also be used to study long term solar terrestrial relationships and as relative dating tools for geological and archaeological archives here we present a new family of spherical harmonic geomagnetic field models spanning the past 9000 yr based on magnetic field directions and intensity stored in archaeological artefacts igneous rocks and sediment records a new modelling strategy introduces alternative data treatments with a focus on extracting more information from sedimentary data to reduce the influence of a few individual records all sedimentary data are resampled in 50 yr bins which also means that more weight is given to archaeomagnetic data during the inversion the sedimentary declination data are treated as relative values and adjusted iteratively based on prior information finally an alternative way of treating the sediment data chronologies has enabled us to both assess the likely range of age uncertainties often up to and possibly exceeding 500 yr and adjust the timescale of each record based on comparisons with predictions from a preliminary model as a result of the data adjustments power has been shifted from quadrupole and octupole to higher degrees compared with previous holocene geomagnetic field models we find evidence for dominantly westward drift of northern high latitude high intensity flux patches at the core mantle boundary for the last 4000 yr the new models also show intermittent occurrence of reversed flux at the edge of or inside the inner core tangent cylinder possibly originating from the equator less

the structure and temporal stability of jupiter s zonal winds a study of the north tropical region abstract this paper investigates possible long term zonal wind variations using voyager 1979 hubble space telescope hst 1995 1997 1998 and galileo orbiter 1997 data that has all been processed and analyzed in the same manner for consistency previous attempts to measure the zonal wind profile in voyager data had yielded inconsistent results for the maximum eastward jet near 23 7 n latitude from different studies a p ingersoll et al 1979 nature 280 773 775 ibid 1981 j geophys res 86 8733 8743 t maxworthy 1984 planet space sci 32 1053 1058 s limaye 1986 icarus 65 335 352 this paper compares previous measurements and includes new independent analysis to conclude that the correct wind jet velocity at the time of voyager is close to 182 m s 1 most consistent with the reported results of maxworthy 1984 in the data sets from different epochs the overall shape of the wind profile and locations of the prograde and retrograde jets remain constant but there are amplitude changes at a few latitudes the largest velocity deviations between the voyager and the 1995 1997 hst profiles occurred in the maximum eastward jet near 23 7 n and at 6 s and 20 s planetographic latitude possible causes for an apparent zonal wind decrease were explored using galileo visible and hst near infrared data and the wind velocity change was determined to be real a very definite change in cloud structure and brightness has also occurred at 23 7 n additionally surface brightness changes seen at 6 s and 20 s also correlated with changes in wind speed hst wfpc2 data obtained in 1998 showed the recovery of the 23 7 n region to a voyager like appearance and an increase in wind velocity to the voyager value

the time dependence of intense archeomagnetic flux patches 1 the long term temporal behavior of intense geomagnetic flux patches at the core mantle boundary and the relation with lower mantle lateral heterogeneity are under debate we apply an algorithm to detect centers of intense flux patches and track their time evolution in a recent archeomagnetic field model in order to study the kinematics of such intense magnetic flux patches on millennial timescale we find that most intense flux patches appear near the edge of the tangent cylinder quasi stationary periods with small oscillations of patches occur more than drifts detailed comparison of the archeomagnetic patches behavior with that seen in numerical dynamos with tomographic heat flux boundary conditions suggests that core mantle thermal coupling could be the cause of a statistical preference for some longitudes on the long term which does not exclude significant time spent away from the preferred longitudes this could explain the roughly coincident locations of high latitude patches in the historical geomagnetic field with that of the time average paleomagnetic field together with the much weaker patches intensity in the latter alternating eastward and westward drifts are also observed the drifts are more westward than eastward especially in the southern hemisphere indicating that the time average zonal core flow may also be driven by core mantle thermal coupling an average patch lifetime of 300 years is found which we hypothesize may indicate the vortex lifetime in the outer core

geomagnetic field evolution during the laschamp excursion abstract since the last geomagnetic reversal 780 000 years ago the earth s magnetic field repeatedly dropped dramatically in intensity this has often been associated with large variations in local field direction but without a persistent global polarity flip the structure and dynamics of geomagnetic excursions and especially the difference between excursions and polarity reversals have remained elusive so far for the best documented excursion the laschamp event at 41 000 years bp we have reconstructed the evolution of the global field morphology by using a bayesian inversion of several high resolution palaeomagnetic records we have obtained an excursion scenario in which inverse magnetic flux patches at the core mantle boundary emerge near the equator and then move poleward contrary to the situation during the last reversal leonhardt r fabian k 2007 paleomagnetic reconstruction of the global geomagnetic field evolution during the matuyama brunhes transition iterative bayesian inversion and independent verification earth planet sci lett 253 172 195 these flux patches do not cross the hydrodynamic boundary of the inner core tangent cylinder while the last geomagnetic reversal began with a substantial increase in the strength of the non dipolar field components prior to the laschamp excursion both dipolar and non dipolar field decay at the same rate this result suggests that the nature of an upcoming geomagnetic field instability can be predicted several hundred years in advance even though during the laschamp excursion the dipolar field at the earth s surface was dominant the reconstructed dynamic non dipolar components lead to considerable deviations among predicted records at different locations the inverse model also explains why at some locations no directional change during the laschamp excursion is observed

can downwelling at the top of the earth s core be detected in the geomagnetic secular variation abstract it has been argued based on recent seismic and mineral physics studies that the top of earth s liquid outer core is stably stratified here i analyze persistent geomagnetic secular variation features on the core mantle boundary to examine whether a kinematic signature of core fluid upwelling downwelling can be detected i focus on regions of intense high latitude geomagnetic flux patches that may be maintained by fluid downwelling in order to identify persistent patterns the radial field and its secular variation are stacked in the flux patch moving reference frame these stacked images are compared with forward solutions to the radial induction equation based on idealized field flow models clear advective secular variation signature below north america indicates that these intense flux patches may exhibit significant mobility stretching signature in the form of persistent positive secular variation correlated with the intense flux patch below the southern indian ocean may be considered as regional scale geomagnetic evidence for whole core convection although pure toroidal flow cannot be outruled

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

a reduced stochastic model of core surface dynamics based on geodynamo simulations we make use of recent geodynamo simulations to propose a reduced stochastic model of the dynamics at the surface of earth s core on decadal and longer periods this model replicates the most energetic eigen directions of the geodynamo computation towards shorter timescales it proposes a compensation for weaknesses of these simulations this model furthermore accounts for the signature in the geomagnetic secular variation of errors of representativeness associated with unresolved processes we incorporate the reduced stochastic model into a geomagnetic data assimilation algorithm an augmented state ensemble kalman filter and apply it to re analyze magnetic field changes over the period 1880 2015 errors of representativeness appear to be responsible for an important fraction of the observed changes in the secular variation as it is the case in the dynamo simulation recovered core surface motions are primarily symmetric with respect to the equator we observe the persistence of the eccentric westward gyre over the whole studied era and vortices that partly follow isocontours of the radial magnetic field at the core surface our flow models provide a good fit to decadal changes in the length of day and predict its interannual variations over 1940 2005 the largest core flow acceleration patterns are found in an equatorial belt below 10 in latitude and are associated with non axisymmetric features no systematic longitudinal drift of acceleration patterns is found even over the past decades where satellite data are available the acceleration of the high latitude westward jet in the pacific hemisphere is during the satellite era a factor 5 smaller than previously reported and its structure shows some evidence for equatorial asymmetry the era 1 of continuous satellite records provides enhanced contrast on the rapid core flow variations the proposed assimilation algorithm offers the prospect of evaluating earth likeness of geodynamo simulations

coupled dynamics of earth s geomagnetic westward drift and inner core super rotation this phd work focuses on the rotational dynamics of the coupled inner core outercore mantle system the conservation of the angular momentum our coupled earth model indeed involves two direct electromagnetic torques at the fluid core boundaries and a remote gravitational torque between the inner core and the mantle the rotational dynamics is described by four typical shears and studied in convective numerical simulations of the geodynamo which are able to reproduce the main characteristics of the geomagnetic field and its secular variation this secular variation is mainly embodied by the westward drift of magnetic flux patches at the cmb concentrated on the equator of the atlantic hemisphere and is well documented for the last four centuries we provide constrains on the inner core differential rotation by expressing its link to the geomagnetic westward drift this is performed through the formulation and the validation of dynamical electromagnetic torque models which are then introduced in the conservation of the angular momentum of the system in the long term state the global shear in the fluid outer core is distributed between the westward drift and the differential rotation of the inner core in proportions controlled by the state of couplings as a present day estimate of this shear is close to the observed westward drift we conclude there is no differential rotation of the inner core on time average in the time dependent state we observed that the strength of gravitational coupling is the dominant parameter this places limit on the decadal fluctuations of the inner core differential rotation which should not exceed a few hundredths of degree per year

jupiter s interior and deep atmosphere the initial pole to pole passes with the juno spacecraft on 27 august 2016 the juno spacecraft acquired science observations of jupiter passing less than 5000 kilometers above the equatorial cloud tops images of jupiter s poles show a chaotic scene unlike saturn s poles microwave sounding reveals weather features at pressures deeper than 100 bars dominated by an ammonia rich narrow low latitude plume resembling a deeper wider version of earth s hadley cell near infrared mapping reveals the relative humidity within prominent downwelling regions juno s measured gravity field differs substantially from the last available estimate and is one order of magnitude more precise this has implications for the distribution of heavy elements in the interior including the existence and mass of jupiter s core the observed magnetic field exhibits smaller spatial variations than expected indicative of a rich harmonic content

jupiter new estimates of the mean zonal flow at the cloud level abstract previous estimates of the mean zonal flow on jupiter from voyager images by ingersoll et al a p ingersoll r f beebe j l mitchell g w garneau g m yagi and j p mueller 1981 j geophys res 86 8733 8743 and by limaye et al s s limaye h e revercomb l a sromovsky r j krauss v e suomi s a collins and c c avis 1982 j atmos sci 39 1413 1432 showed good agreement in the locations of the easterly and westerly jets but differed somewhat in magnitude recent measurements of the high speed jet located near 24 north plane topographic latitude by t maxworthy 1984 planet space sci 32 1053 1058 from high spatial and temporal resolution voyager images indicate that both ingersoll et al and limaye et al underestimated the magnitude of the jet by more than 30 40 msec 1 in an attempt to examine the differences in the magnitude of the jovian jets determined from voyager 1 and 2 images a new approach to determine the zonal mean east west component of motion was investigated the new technique based on simple digital pattern matching approach and applied on pairs of mapped images cylindrical mosaics yields a profile of the mean zonal component that reproduces the exact locations of the easterly and westerly jets between 60 latitude not only do the jet magnitudes but also the wings of the jets agree remarkably well from mosaic pair to pair further the latitudinal resolution is five midlatitudes to eight times equatorial greater than previous results results have been obtained for all of the voyager 1 and 2 cylindrical mosaics the correlation coefficient between voyager 1 and voyager 2 average mean zonal flow between 60 latitude determined from violet filter mosaics is 0 998 a slight latitude offset possibly due to navigation errors is detectable 0 2 latitude average in the voyager 1 data independent cloud motion measurements in two high resolution image pairs orange and violet acquired from voyager 1 cameras agree well with the average mean zonal flow for the fastest jovian jet at 23 8 n latitude comparison with maxworthy s 1984 results suggests longitudinal variations in cloud motions approaching about 20 msec 1 in particular the jet magnitude is about 163 7 rms msec 1 which compares well with 182 10 msec 1 reported by maxworthy there is excellent agreement in the location of the peak magnitude as well as its shape the time average voyager 2 mean zonal flow profile with latitude is presented in a table

on the latitude dependence of drift velocity of the geomagnetic main field and its secular variation abstract there is an apparent difference in the westward drift between the geomagnetic main field and its time derivative secular variation the drift velocity of the main field is about 0 2 year definitely lower than that of the secular variation 0 3 year the drift velocity of the main field appears to change with latitude being low at high latitudes and higher at low latitudes whereas the velocity of the secular variation is nearly constant irrespective of latitude this paper examines what causes this difference by adopting the drifting and standing field model that assumes the geomagnetic field consists of the field steadily drifting westwards and the field remaining at nearly the same location in this study we confirm that the existence of the non drifting standing field significantly affects the estimate of the drift velocity of the total field i e the main field and makes it slower than that of the secular variation the drifting field is intense in low latitudes with its maximum at the equator while the standing field dominates in higher latitudes as a consequence reduction of the apparent drifting velocity of the total field by the standing field is conspicuous in higher latitudes and less so in low latitudes this creates the observed latitudinal structure of the drift velocity of the main field on the other hand the drift velocity of the secular variation is less affected by existence of the standing field and mostly reflects the velocity of the drifting field that is almost constant with latitude the velocity of the secular variation thus becomes almost uniform independent of latitude the observed difference between the main field and the secular variation is naturally derived from the drifting and standing field model this implies that physical mechanisms to generate the drifting and standing fields can be considered independently

dynamics of jupiter s equatorial region at cloud top level from cassini and hst images abstract we present a study of the equatorial region of jupiter between latitudes 15 s and 15 n based on cassini iss images obtained during the jupiter flyby at the end of 2000 and hst images acquired in may and july 2008 we examine the structure of the zonal wind profile and report the detection of significant longitudinal variations in the intensity of the 6 n eastward jet up to 60 m s 1 in cassini and hst observations these longitudinal variations are in the hst case associated with different cloud morphology photometric and radiative transfer analysis of the cloud features used as tracers in hst images show that at most there is only a small height difference no larger than 0 5 1 scale heights between the slow 100 m s 1 and fast 150 m s 1 moving features this suggests that speed variability at 6 n is not dominated by vertical wind shears but instead we propose that rossby wave activity is the responsible for the zonal variability removing this variability we find that jupiter s equatorial jet is actually symmetric relative to equator with two peaks of 140 150 m s 1 located at latitudes 6 n and 6 s and at a similar pressure level we also study the local dynamics of particular equatorial features such as several dark projections associated with 5 m hot spots and a large long lived feature called the white spot ws located at 6 s convergent flow at the dark projections appears to be a characteristic which depends on the particular morphology and has only been detected in some cases the internal flow field in the white spot indicates that it is a weakly rotating quasi equatorial anticyclone relative to the ambient meridionally sheared flow

geomechanical characterisation of rock masses in alpine regions the basque arc basque cantabrian basin northern spain the geomechanical characterisation of rock masses in alpine regions is one of the main challenges currently facing rock mechanics these rock masses made up of very different materials and frequently tectonically disturbed are affected by engineering works giving rise to potentially important problems thus in the basque country these materials are at the cause of important fatalities occurring in recent years in this context we aim at characterising these materials with the ultimate purpose of predicting their behaviour the characterisation is initially approached based on the gsi mi and ci parameters following the hoek brown failure criterion this information is supplemented with field and laboratory measurements and by obtaining the rqd and rmr indices using the information obtained from 99 metering stations we develop a graphic classification procedure which allows us to distinguish materials based on their characteristics behaviour type and degree of associated problems and type and effectiveness of solutions provided eight classes of material are established

discrete element modelling of deformation and damage of a roadway driven along an unstable goaf a case study abstract roadways driven alongside a previously extracted longwall panel goaf are a common situation in underground coal mining the unstable goaf can have a significant detrimental impact on the stability of the roadway this paper presents a combined srm udec trigon numerical approach to investigate the failure mechanism of a roadway driven alongside an unstable goaf the synthetic rock mass srm method is used to derive the rock mass properties and the newly developed udec trigon approach is used for simulating brittle fracture and consequent roadway damage the results indicate that the roadway suffers asymmetric damage characterized by a major rib convexity a severe floor heave and a relatively stable roof with limited fracturing this failure mechanism is consistent with field observations a quantitative evaluation of the damage around the roadway indicates that shear failure plays a major role in the roadway damage our study suggests that the proposed combination of srm and the udec trigon is well suited to the evaluation of failure mechanisms around underground coal mine excavations

a study of the stability of jovian zonal winds from hst images 1995 2000 abstract we present a five year study of the temporal stability of jupiter s zonal wind velocity profile at cloud level based on hubble space telescope images obtained from 1995 to 2000 we used the correlation of east west albedo scans in pairs of images separated by one jovian rotation to retrieve the zonal winds the resolution in the hst images ranged from 140 to 190 km pixel 1 independent measurements of the motions of individual cloud tracers were used to control the above profiles three wavelengths were used in this analysis 410 nm violet continuum 892 nm methane absorption band and 953 nm red continuum our study indicates that globally jupiter s zonal flow did not change during this five year interval and it does not depend on the observed wavelengths when comparing our mean profile with that obtained 16 years ago using voyager data we find a reasonable agreement we note however a small shift in the latitude of the jets poleward of latitude 30 probably due to image navigation uncertainties however true changes in the intensity of the jets at 24 n and 32 n are found results also indicate that the 7 s jet has remained stable since the voyager era in addition we extend in this paper our previous study of the 24 n with new data from year 2000 the new data confirm the jet s stability during the 1995 2000 period finally we present the average profile for this period including error estimation in a table that extends the latitudinal coverage of limaye s 1986 icarus 65 335 352 voyager profile up to latitudes 68 s and 77 n

galileo imaging of jupiter s atmosphere the great red spot equatorial region and white ovals during the first six orbits of the galileo spacecraft s prime mission the solid state imaging ssi system acquired multispectral image mosaics of jupiter s great red spot an equatorial belt zone boundary a 5 m hot spot similar to the galileo probe entry site and two of the classic white ovals we present mosaics of each region approximating their appearance at visible wavelengths and showing cloud height and opacity variations the local wind field is derived by tracking cloud motions between multiple observations of each region with time separations of roughly 1 and 10 hr vertical cloud structure is derived in a companion paper by banfieldet al icarus135 230 250 galileo s brief high resolution observations complement earth based and voyager studies and offer local meteorological context for the galileo probe results our results show that the dynamics of the zonal jets and large vortices have changed little since voyager with a few exceptions we detect a cyclonic current within the center of the predominantly anticyclonic great red spot the zonal velocity difference between 0 s and 6 s has increased by 20 m sec 1 we measure a strong northeast flow approaching the hot spot this flow indicates either massive horizontal convergence or the presence of a large anticyclonic vortex southeast of the hot spot the current compact arrangement of two white ovals and a cyclonic structure greatly perturbs the zonal jets in that region

earth s core internal dynamics 1840 2010 imaged by inverse geodynamo modelling inverse geodynamo modelling seeks to estimate the dynamic state of earth s core from geo magnetic data and the statistical information brought by a prior self consistent 3 d numerical model of the geodynamo the method rests on the use of least squares inversions under constraints and estimates hidden quantities by taking advantage of linear relations and long range statistical correlations with the magnetic observations the data together with their error statistics are provided by geomagnetic field models cov obs gufm sat q3 and cm4 covering epochs 1840 2010 the prior numerical model is the recently published coupled earth dynamo the output of which presents a high degree of morphological semblance to the geomagnetic field while reproducing the main features of its secular variation an analysis of the inversion misfits to the data shows that the prior model generally accounts well for the main field and secular variation data within their specified errors throughout the investigated time period inverted core flows are confirmed to be mainly organized in columns parallel to the earth s rotation axis a previously observed giant eccentric columnar gyre of westward drifting flow is found to be present from epoch 1870 onwards and its structure is shown to slowly rotate westwards at a rate up to 0 1 yr 1 confirming an earlier prediction based on direct numerical modelling temporal variations in the axisymmetric part of the gyre accurately account for observed variations of the length of the day in recent epochs inverted magnetic structures support a mechanism of azimuthal flux expulsion by convective columns to explain the origin of low latitude magnetic flux patches existing beneath the atlantic the 1840 2010 time average of the inverted density anomaly field has a longitudinal hemispheric structure with most of the buoyancy in the eastern hemisphere consistent with rapid surges of convective columns imaged in this hemisphere with earlier proposals of a faster inner core freezing there and with a possible east to west convective translation of the solid inner core the typical timescales of flow variation observed in the inversions are two to three times shorter than those naturally produced by a direct simulation of the prior model underlining its limits in fully rendering the earth s core short timescale dynamics

meteorology of jupiter s equatorial hot spots and plumes from cassini we present an updated analysis of jupiter s equatorial meteorology from cassini observations for two months preceding the spacecraft s closest approach the imaging science subsystem iss onboard regularly imaged the atmosphere we created time lapse movies from this period in order to analyze the dynamics of equatorial hot spots and their interactions with adjacent latitudes hot spots are relatively cloud free regions that emit strongly at 5 lm improved knowledge of these features is crucial for fully understanding galileo probe measurements taken during its descent through one hot spots are quasistable rectangular dark areas on visible wavelength images with defined eastern edges that sharply contrast with surrounding clouds but diffuse western edges serving as nebulous boundaries with adjacent equatorial plumes hot spots exhibit significant variations in size and shape over timescales of days and weeks some of these changes correspond with passing vortex systems from adjacent latitudes interacting with hot spots strong anticyclonic gyres present to the south and southeast of the dark areas appear to circulate into hot spots impressive bright white plumes occupy spaces in between hot spots compact cirrus like scooter clouds flow rapidly through the plumes before disappearing within the dark areas these clouds travel at 150 200 m s 1 much faster than the 100 m s 1 hot spot and plume drift speed this raises the possibility that the scooter clouds may be more illustrative of the actual jet stream speed at these latitudes most previously published zonal wind profiles represent the drift speed of the hot spots at their latitude from pattern matching of the entire longitudinal image strip if a downward branch of an equatorially trapped rossby wave controls the overall appearance of hot spots however the westward phase velocity of the wave leads to underestimates of the true jet stream speed

emergence and evolution of the south atlantic anomaly revealed by the new paleomagnetic reconstruction shawq2k abstract the south atlantic anomaly saa is one of the most outstanding features of the present geomagnetic field thus a good knowledge of the saa is clue for a better understanding of the dynamical behavior of the geomagnetic field to achieve this goal paleomagnetic data are crucial since they provide the unique way to investigate past changes in the earth s magnetic field here we present a new global geomagnetic field reconstruction the shawq2k model which is based on a critical revision of the global archeomagnetic and volcanic dataset the new model provides an improved description of the geomagnetic field during the last 2 millennia and yields surprising outcomes about the emergence and development of the saa it shows that the reversed flux patch observed at the core mantle boundary and linked to the saa emerged in the southern hemisphere from at least 950 ad this patch moved westward from the equator to southern latitudes being clearly isolated after 1400 ad in addition since 1550 ad a second reversed flux patch moving northeastward is observed in the north atlantic the new data now available for the southern hemisphere coming from africa and south america together with the use of an appropriated weighting scheme in the modeling process have improved our understanding of past geomagnetic field behavior and showed new evolutionary aspects of the saa

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

drifting and standing fields in the geomagnetic field for the past 400 years abstract based on the field model by jackson et al 2000 we reanalyzed the data of historical times and decomposed the geomagnetic field into drifting and standing fields it has been confirmed that the results are consistent with the earlier analyses when the field is expressed in a spherical harmonic series the drifting field is characterized by two remarkable features one is that the drifting field is represented mostly by sectorial harmonics and the other is that the drift velocity does not differ significantly between the harmonics the standing field that remains after subtraction of the drifting field from the main geomagnetic field is stronger than the drifting field the predominance of sectorial terms in the drifting field means that the vertical component for instance of the drifting field is symmetric about the equator on the other hand the standing field is antisymmetric due to this difference the drifting field largely controls the geomagnetic secular variation in the low latitude region whereas the standing field dominates in the middle and higher latitudes

cassini imaging of jupiter s atmosphere satellites and rings the cassini imaging science subsystem acquired about 26 000 images of the jupiter system as the spacecraft encountered the giant planet en route to saturn we report findings on jupiter s zonal winds convective storms low latitude upper troposphere polar stratosphere and northern aurora we also describe previously unseen emissions arising from io and europa in eclipse a giant volcanic plume over io s north pole disk resolved images of the satellite himalia circumstantial evidence for a causal relation between the satellites metis and adrastea and the main jovian ring and information on the nature of the ring particles

relating the south atlantic anomaly and geomagnetic flux patches abstract the south atlantic anomaly saa is a region of weak geomagnetic field intensity at the earth s surface which is commonly attributed to reversed flux patches rfps on the core mantle boundary cmb while the saa is clearly affected by the reversed flux region below the south atlantic we show that the relation between the intensity minimum at earth s surface and rfps is not straightforward we map a field dependent intensity kernel constable 2007a to study the relation between the radial geomagnetic field at the cmb and the field intensity at earth s surface synthetic tests highlight the role of specific patches reversed and normal in determining the location of the surface intensity minimum and demonstrate that the saa can indeed be explained by a few intense patches we show that the level of axial dipolarity of the field determines the stability of the relation between the saa minimum and rfps the present position of the saa minimum is determined by the interplay among several robust geomagnetic flux patches at the cmb the longitude of the saa minimum appears near the longitude of the patagonia rfp due to the low latitude normal flux patches nfps near africa and mid atlantic which diminish the effect of the africa rfps the latitude of the saa minimum is lower than the patagonia rfp latitude due to the south pacific high latitude nfp and the axial dipole effect the motion of the saa minimum is explained by the motions and changes in intensity of these robust geomagnetic flux patches simple secular variation sv scenarios suggest that while the saa path can be explained by advection its intensity decrease requires magnetic diffusion in addition these sv scenarios provide some speculative predictions for the saa

longitudinal variation and waves in jupiter s south equatorial wind jet abstract a detailed study of the chevron shaped dark spots on the strong southern equatorial wind jet near 7 5 s planetographic latitude shows variations in velocity with longitude and time the presence of the large anticyclonic south equatorial disturbance sed has a profound effect on the chevron velocity causing slower velocities to its east and increasing with distance from the disturbance the chevrons move with velocities near the maximum wind jet velocity of 140 m s as deduced by the history of velocities at this latitude and the magnitude of the symmetric wind jet near 7 n latitude their repetitive nature is consistent with a gravity inertia wave n 75 100 with phase speed up to 25 m s relative to the local flow but the identity of this wave mode is not well constrained however for the first time high spatial resolution movies from cassini images show that the chevrons oscillate in latitude with a 6 7 0 7 day period this oscillating motion has a wavelength of 20 and a speed of 101 3 m s following a pattern similar to that seen in the rossby wave plumes of the north equatorial zone and possibly reinforced by it all dates show chevron latitude variability but it is unclear if this larger wave is present during other epochs as there are no other suitable time series movies that fully delineate it in the presence of multiple wave modes the difference in dominant cloud appearance between 7 n and 7 5 s is likely due to the presence of the great red spot either through changes in stratification and stability or by acting as a wave boundary

modelling the palaeo evolution of the geodynamo although it is known that the geodynamo has been operating for at least 3 2 ga it remains difficult to infer the intensity dipolarity and stability occurrence of reversals of the precam brian magnetic field of the earth in order to assist the interpretation of palaeomagnetic data we produce models for the long term evolution of the geodynamo by combining core ther modynamics with a systematic scaling analysis of numerical dynamo simulations we update earlier dynamo scaling results by exploring a parameter space which has been extended in order to account for core aspect ratios and buoyancy source distributions relevant to earth in the precambrian our analysis highlights the central role of the convective power which is an output of core thermodynamics and the main input of our updated scalings as the thermal evolution of the earth s core is not well known two end member models of heat flow evolution at the core mantle boundary cmb are used respectively terminating at present heat flows of 11 tw high power scenario and 3 tw low power scenario the resulting models predict that until the appearance of the inner core a thermal dynamo driven only by secular cooling and without any need for radioactive heating can produce a dipole moment of strength comparable to that of the present field thus precluding an interpretation of the oldest palaeomagnetic records as evidence of the inner core presence the observed lack of strong long term trends in palaeointensity data throughout the earth s history can be rationalized by the weakness of palaeointensity variations predicted by our models relatively to the data scatter specifically the most significant internal magnetic field increase which we predict is associated to the sudden power increase resulting from inner core nucleation but the dynamo becomes deeper seated in the core thus largely cancelling the increase at the core and earth surface and diminishing the prospect of observing this event in palaeointensity data our models additionally suggest that the geodynamo has lied close to the transition to polarity reversals throughout its history in the precambrian we predict a dynamo with similar dipolarity and less frequent reversals than at present times due to conditions of generally lower convective forcing quantifying the typical cmb heat flow variation needed for the geodynamo to cross the transition from a reversing to a non reversing state we find that it is unlikely that such a variation may have caused superchrons in the last 0 5 ga without shutting down dynamo action altogether

new approaches to the characterization of clay bearing densely jointed and weak rock masses various classification systems for rock masses have been used in engineering applications however these systems are not sufficient to classify clay bearing densely jointed and weak rock masses among the factors that cause this deficiency are the damaging effect of water on rocks which has not sufficiently been described in the existing classification systems this factor was allowed for by the inclusion of new parameters in the modified rock mass classification m rmr system developed in recent years the aim of this study is to make contributions to the m rmr classification system and to overcome the difficulties encountered in the classification procedure for this purpose data were collected for rock mass classification from 13 clay bearing densely jointed and weak rock masses in four regions yatagan soma baskoyak and guvenc located in the western and middle parts of turkey the discontinuity data were collected by the line survey technique and evaluated by statistical methods in addition to the uniaxial compressive strength test for the determination of the rating for intact rock strength the block punch index test was also considered as an alternative parameter and the slake durability index test and x ray diffraction analyses were performed on 104 samples collected from the studied rock masses further the weathering coefficient wc determined by schmidt hammer was considered as an alternative parameter for the determination of the rating for joint weathering as a result of statistical evaluation of data obtained from the field and laboratory studies it has been concluded that the block punch index bpi could be used as an alternative parameter for the determination of the rating for intact rock strength in the m rmr classification system it was also found that the slake durability index id determined at the fourth cycle would be a more effective approach than the second cycle index that has previously been used to express the unfavourable effect of water on the rock mass the propositions made in the present work to contribute to the m rmr system were tested in back analyses of three previously failed slopes and the performance of the system with the newly introduced improvements appeared to be satisfactory

modelling the geomagnetic field from syntheses of paleomagnetic data abstract this review examines results from time varying geomagnetic field models that span several thousand years and from variations in dipole moment strength up to million year time scales for the past 400 years twin magnetic flux lobes bordering the inner core tangent cylinder in both northern and southern hemispheres dominate the geomagnetic field and appear more or less fixed in location in contrast the millennial scale view shows that such features are quite mobile and subject to morphological changes on time scales of a few centuries to a thousand years possibly reflecting large scale reorganization of core flow the lobes rarely venture into the pacific hemisphere and average fields over various time scales generally reveal two or three sets of lobes of diminished amplitude thus millennial scale models are suggestive of thermal core mantle coupling generating a weak bias in the average field rather than a strong inhibition of large scale field changes the recovery of variations in dipole moment on million year time scales allows frequency domain analyses to search for characteristic time scales for core dynamics that might be associated with excursion and reversal rate time taken for reversals or any signs of control by earth s orbital parameters the spectrum is characteristically red for the time interval 0 160 ma suggesting non stationarity associated with average reversal rate changes probably reflecting the impact of superchrons and a continually evolving core distinct regimes of power law decay with frequency may reflect different physical processes contributing to the secular variation evidence for non stationarity at shorter time scales is also present in dipole moment variations over 0 2 ma with average growth rate faster than the decay process rates of change of dipole moment and rapid local field variations found in the paleomagnetic record are evaluated in the context of the 400 year historical record and the spectrum of geomagnetic variations for 0 160 ma

peering through jupiter s clouds with radio spectral imaging radio wavelengths can probe altitudes in jupiter s atmosphere below its visible cloud layers we used the very large array to map this unexplored region down to 8 bar 100 kilometers below the visible clouds our maps reveal a dynamically active planet at pressures less than 2 to 3 bar a radio hot belt exists consisting of relatively transparent regions a low ammonia concentration nh3 being the dominant source of opacity probing depths to over 8 bar these regions probably coincide with 5 micrometer hot spots just to the south we distinguish an equatorial wave bringing up ammonia gas from jupiter s deep atmosphere this wave has been theorized to produce the 5 micrometer hot spots we observed the predicted radio counterpart of such hot spots

characterization of jointed rock masses for geotechnical classifications utilized in mine shaft stability analyses abstract in the divrigi open pit iron mine in turkey extracted ore is initially crushed in an underground chamber this chamber was previously located 54 m below the bottom level of the mine which was linked by a vertical shaft because of the progression in the mine operations the mine management decided to shift the chamber to a depth of 264 15 m below the surface a borehole called as ynk 3 which was no closer than 15 m to the existing shaft that was 4 m in diameter and 54 m in length was drilled to a vertical distance of 264 15 m although the first 54 m was drilled in a coreless manner the drill cores obtained from the remaining 210 15 m were used in the rock mass characterization studies for the design of the shaft support the rock formations encountered during shaft sinking which were generally jointed rock masses were classified into structural regions and domains for geological and geotechnical definition initially the original rock mass rating rmr and quality q systems were used for rock mass characterization but difficulties were experienced in determining a number of input parameters required particularly by the rmr system a comprehensive examination of the drawbacks encountered directed us to the modified rmr m rmr system in this paper the original rmr and q and modified m rmr rock mass classification systems are compared in a detailed discussion of our results in addition the classification results were tested using the hoek brown failure criterion to compare the ratings presented by classification systems

on core surface flows inferred from satellite magnetic data abstract satellite data allows the magnetic field produced by the dynamo within the earth s core to be imaged with much more accuracy than previously possible with only ground based data changes in this magnetic field can in turn be used to make some inferences about the core surface flow responsible for them in this paper we investigate the improvement brought to core flow computation by new satellite data based core magnetic field models it is shown that the main limitation now encountered is no longer the now high accuracy of those models but the non modelled secular variation produced by interaction of the non resolvable small scales of the core flow with the core field and by interaction of the partly resolvable large scales of the core flow with the small scales of the core field unfortunately masked by the crustal field we show how this non modelled secular variation can be taken into account to recover the largest scales of the core flow in a consistent way we also investigate the uncertainties this introduces in core flows computed with the help of the frozen flux and tangentially geostrophic assumptions it turns out that flows with much more medium and small scales than previously thought are needed to explain the satellite data based core magnetic field models it also turns out that a significant fraction of this flow unfortunately happens to be non recoverable being either non resolvable because too small scale or invisible because in the kernel of the inverse method even though it produces the detectable non modelled secular variation applying this to the magsat 1980 to orsted 2000 field changes leads us to conclude that a flow involving at least strong retrograde vortices below the atlantic hemisphere some less resolved prograde vortices below the pacific hemisphere and some poorly resolved and partly non resolvable polar vortices is needed to explain the 1980 2000 satellite era average secular variation the characteristics of the fraction of the secular variation left unexplained by this flow are also discussed

changes in jupiter s zonal velocity between 1979 and 2008 abstract we show that the peak velocity of jupiter s visible cloud level zonal winds near 24 n planetographic increased from 2000 to 2008 this increase was the only change in the zonal velocity from 2000 to 2008 for latitudes between 70 that was statistically significant and not obviously associated with visible weather we present the first automated retrieval of fast 130 m s 1 zonal velocities at 8 n planetographic latitude and show that some previous retrievals incorrectly found slower zonal winds because the eastward drift of the dark projections associated with 5 m hot spots fooled the retrieval algorithms we determined the zonal velocity in 2000 from cassini images from nasa s planetary data system using a global method similar to previous longitude shifting correlation methods used by others and a new local method based on the longitudinal average of the two dimensional velocity field we obtained global velocities from images acquired in may 2008 with the wide field planetary camera 2 wfpc2 on the hubble space telescope hst longer term variability of the zonal winds is based on comparisons with published velocities based on 1979 voyager 2 and 1995 1998 hst images fluctuations in the zonal wind speeds on the order of 10 m s 1 on timescales ranging from weeks to months were found in the 1979 voyager 2 and the 1995 1998 hst velocities in data separated by 10 h we find that the east west velocity uncertainty due to longitudinal fluctuations are nearly 10 m s 1 so velocity fluctuations of 10 m s 1 may occur on timescales that are even smaller than 10 h fluctuations across such a wide range of timescales limit the accuracy of zonal wind measurements the concept of an average zonal velocity may be ill posed and defining a temporal mean zonal velocity as the average of several zonal velocity fields spanning months or years may not be physically meaningful at 8 n we use our global method to find peak zonal velocities of 110 m s 1 in 2000 and 130 m s 1 in 2008 zonal velocities from 2000 cassini data produced by our local and global methods agree everywhere except in the vicinity of 8 n there the local algorithm shows that the east west velocity has large variations in longitude vast regions exceed 140 m s 1 our global algorithm and all of the velocity extraction algorithms used in previously published studies found the east west drift velocities of the visible dark projections rather than the true zonal velocity at the visible cloud level therefore the apparent increase in zonal winds between 2000 and 2008 at 8 n is not a true change in zonal velocity at 7 3 n the galileo probe found zonal velocities of 170 m s 1 at the 3 bar level if the true zonal velocity at the visible cloud level at this latitude is 140 m s 1 rather than 105 m s 1 then the vertical zonal wind shear is much less than the currently accepted value

simple models of fluid flow at the core surface derived from geomagnetic field models summary we examine the problem of determining the fluid flow at the core surface given a model of the temporal variation of the magnetic field seeking to fit the field over a finite time interval the flow is assumed steady over the time interval and we adopt the frozen flux approximation we produce a range of solutions of varying complexity and subject to different constraints estimate the errors on the solutions and assess their consistency with the underlying assumptions we find both direct evidence for ageostrophic flow in the form of flow across the geographical equator and indirect evidence in the form of poorer fits to the field when the flow is contained to be geostrophic on account of this evidence we do not adopt the geostrophic approximation however we find that unconstrained flows are poorly determined and consider the various alternatives for producing better determined solutions we choose to restrict our attention to determining the large scale toroidal part of the flow and find a simple pattern of flow which is nearly symmetric about the equator from a sequence of maps of the flow over 5 year time intervals back to 1915 we are still able to identify many of the basic aspects of this simple pattern but changes in the flow pattern are discernible although our models of the flow explain a large proportion of the signal typically 95 per cent of the variance the fits which we obtain are not as good as might be expected failure of the underlying assumptions together with our decision to map only the large scale toroidal part of the flow explains the poorer than expected fit

changes in jupiter s zonal wind profile preceding and during the juno mission abstract we present five epochs of wfc3 hst jupiter observations taken between 2009 2016 and extract global zonal wind profiles for each epoch jupiter s zonal wind field is globally stable throughout these years but significant variations in certain latitude regions persist we find that the largest uncertainties in the wind field are due to vortices or hot spots and show residual maps which identify the strongest vortex flows the strongest year to year variation in the zonal wind profiles is the 24 n jet peak numerous plume outbreaks have been observed in the northern temperate belt and are associated with decreases in the zonal velocity and brightness we show that the 24 n jet peak velocity and brightness decreased in 2012 and again in late 2016 following outbreaks during these years our february 2016 zonal wind profile was the last highly spatially resolved measurement prior to juno s first science observations the final 2016 data were taken in conjunction with juno s perijove 3 pass on 11 december 2016 and show the zonal wind profile following the plume outbreak at 24 n in october 2016

a dispersive wave pattern on jupiter s fastest retrograde jet at 20 s abstract a compact wave pattern has been identified on jupiter s fastest retrograding jet at 20 s the sebs on the southern edge of the south equatorial belt the wave has been identified in both reflected sunlight from amateur observations between 2010 and 2015 thermal infrared imaging from the very large telescope and near infrared imaging from the infrared telescope facility the wave pattern is present when the seb is relatively quiescent and lacking large scale disturbances and is particularly notable when the belt has undergone a fade whitening it is generally not present when the seb exhibits its usual large scale convective activity rifts tracking of the wave pattern and associated white ovals on its southern edge over several epochs have permitted a measure of the dispersion relationship showing a strong correlation between the phase speed 43 2 to 21 2 m s and the longitudinal wavelength which varied from 4 4 to 10 0 longitude over the course of the observations infrared imaging sensing low pressures in the upper troposphere suggest that the wave is confined to near the cloud tops the wave is moving westward at a phase speed slower i e less negative than the peak retrograde wind speed 62 m s and is therefore moving east with respect to the sebs jet peak unlike the retrograde nebn jet near n which is a location of strong vertical wind shear that sometimes hosts rossby wave activity the sebs jet remains retrograde throughout the upper troposphere suggesting the sebs pattern cannot be interpreted as a classical rossby wave 2d windspeeds and thermal gradients measured by cassini in 2000 are used to estimate the quasi geostrophic potential vorticity gradient as a means of understanding the origin of the a wave we find that the vorticity gradient is dominated by the baroclinic term and becomes negative changes sign in a region near the cloud top level 400 700 mbar associated with the sebs such a sign reversal is a necessary but not sufficient condition for the growth of baroclinic instabilities which is a potential source of the meandering wave pattern

equatorially dominated magnetic field change at the surface of earth s core slow temporal variations in earth s magnetic field originate in the liquid outer core we analyzed the evolution of nonaxisymmetric magnetic flux at the core surface over the past 400 years we found that the most robust feature is westward motion at 17 kilometers per year in a belt concentrated around the equator beneath the atlantic hemisphere surprisingly this motion is dominated by a single wavenumber and persists throughout the observation period this phenomenon could be produced by an equatorial jet of core fluid by hydromagnetic wave propagation or by a combination of both discrimination between these mechanisms would provide useful constraints on the dynamics of earth s core

rapidly changing flows in the earth s core variations in the earth s magnetic field over a span of a few months can be resolved despite the potential filtering effects of the electrically conducting mantle and are indicative of rapid flow in the earth s outer core

estimation of rock mass deformation modulus and strength of jointed hard rock masses using the gsi system abstract rock mass characterization is required for many applications in rock engineering practice including excavation design support design stope design amongst others for these purposes it is necessary to obtain design input parameters such as deformation moduli and strength parameters for numerical modeling although such parameters can ultimately be determined from in situ tests at the preliminary design stage where access to underground is limited the practical way to obtain these parameters is to apply a rock mass classification system to characterize the rock mass and estimate the rock mass properties over the years many classification systems such as rqd rock mass rating q and geological strength index gsi systems have been developed amongst them the q system is widely used for rock support system design and the gsi system is used for estimating design parameters the gsi system is the only rock mass classification system that is directly linked to engineering parameters such as mohr coulomb hoek brown strength parameters or rock mass modulus however the application of the existing gsi system is hindered by the facts that the use of the system is to some extent subjective and requires long term experience in the present study a quantitative approach to assist in the use of the gsi system is presented it employs the block volume and a joint condition factor as quantitative characterization factors the approach is built on the linkage between descriptive geological terms and measurable field parameters such as joint spacing and joint roughness the newly developed approach adds quantitative means to facilitate use of the system especially by inexperienced engineers the gsi system is applied to characterize the jointed rock masses at two underground powerhouse cavern sites in japan gsi values are obtained from block volume and joint condition factor which in turn are determined from site construction documents and field mapping data based on gsi values and intact rock strength properties equivalent mohr coulomb strength parameters and elastic modulus of the jointed rock mass are calculated and compared to in situ test results the point estimate method is implemented to approximate the mean and variance of the mechanical properties of the jointed rock masses it is seen that both the means and variances of strength and deformation parameters predicted from the gsi system are in good agreement with field test data

on the geomagnetic secular variation in the pacific region abstract it is widely believed that in the pacific region the geomagnetic secular variation is low and that the non dipole field is weak this is also known as hemispherical asymmetry between the pacific and the atlantic hemispheres representing the low secular variation in the pacific hemisphere with this characteristic feature a question has been left unsolved whether it is a permanent feature or a transient one reexamination of the geomagnetic field for the past 400 years indicates that in the early 17th century the non dipole field was not weak nor the secular variation was low in the pacific region implying that the hemispherical asymmetry is not a permanent phenomenon this paper examines the secular variation for the past 400 years from viewpoint of drifting and standing field model it has been found that the low secular variation in the pacific region is mainly caused by the drift of the drifting field at the earth s surface the drifting field is dominated by spherical harmonics y 2 2 with two pairs of ridges and troughs with their axes aligned in the meridional direction the two pairs are not equal one pair is stronger than the other movements of the different magnitude of the pairs are considered to have caused the hemispherical asymmetry of the secular variation for recent years giving rise to the non weak field in the pacific region in the early 17th century

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

geomagnetic secular variation we analyse over 175000 magnetic observations from an interval spanning 1695 1980 to produce a sequence of maps of the magnetic field at the core mantle boundary we find that even the earlier data enable us to determine reliable maps we produce these maps at approximately 60 year intervals through the eighteenth and nineteenth centuries and at 10 year intervals in the twentieth century this span of maps is long enough to render straightforward the distinction between static and drifting features in the field we observe that some features show no sign whatsoever of drift over the entire 285 year time interval although others drift westwards in particular we observe that the secular variation is very low beneath the pacific ocean but beneath southern africa and the south atlantic ocean we observe rapid secular variation we interpret the morphology of the static field in terms of a simple model of the dynamo and conjecture that interactions between the core and the mantle are an important element of the process as part of the static field we identify four main concentrations of flux two in each hemisphere at high latitudes these features largely account for the earth s axial dipole moment we find unequivocal evidence that magnetic flux has not remained frozen over the time span of our models much of the diffusive behaviour that we identify is associated with the formation of a pair of flux spots a core spot beneath southern africa early in this century nevertheless we are able to construct maps that satisfy a set of necessary conditions for frozen flux and use these maps to construct maps of the core surface fluid flow based on the steady flow hypothesis although we find no strong evidence against the steady flow hypothesis we do find some grounds on which to doubt the validity of the flow maps

mantle driven geodynamo features effects of compositional and narrow d anomalies abstract lower mantle heterogeneity could cause deviations from axial symmetry in geodynamo properties global tomography models are commonly used to infer the pattern of core mantle boundary heat flux via a linear relation that corresponds to a purely thermal interpretation of lower mantle seismic anomalies ignoring both non thermal origins and non resolved small scales here we study the possible impact on the geodynamo of narrow thermal anomalies in the base of the mantle originating from either compositional heterogeneity or sharp margins of large scale features a heat flux boundary condition composed of a large scale pattern and narrow ridges separating the large scale positive and negative features is imposed on numerical dynamos we find that hot ridges located to the west of a positive large scale core mantle boundary heat flux anomaly produce a time average narrow elongated upwelling a flow barrier at the top of the core and intensified low latitudes magnetic flux patches when the ridge is located to the east of a positive core mantle boundary heat flux anomaly the associated upwelling is weaker and the homogeneous dynamo westward drift leaks precluding persistent intense low latitudes magnetic flux patches these signatures of the core mantle boundary heat flux ridge are evident in the north south component of the thermal wind balance based on the pattern of lower mantle seismic tomography masters et al 2000 we hypothesize that hot narrow thermal ridges below central asia and the indian ocean and below the american pacific coast produce time average fluid upwelling and a barrier for azimuthal flow at the top of the core east of these ridges below east asia and oceania and below the americas time average intense geomagnetic flux patches are expected

numerical investigation of the scale effect and anisotropy in the strength and deformability of coal abstract the decrease in strength and stiffness of coal with increase in specimen size has long been recognized as scale effect in this study a synthetic rock mass srm approach has been used to investigate this scale effect and the anisotropy of coal a discrete fracture network dfn for the coal was created and then embedded into bonded particle models to form a range of varying size of srm coal specimens unconfined compression tests on the srm specimens showed that the srm approach is capable of quantitatively reproducing the dependency of the strength and stiffness on the size of the coal specimens the strength and stiffness anisotropy of coal can also be reproduced the numerical results are shown to be in good agreement with published laboratory and field test results

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