flow modeling and permeability estimation using borehole flow logs in heterogeneous fractured formations a numerical model of flow in the vicinity of a borehole is used to analyze flowmeter data obtained with high resolution flowmeters the model is designed to 1 precisely compute flow in a borehole 2 approximate the effects of flow in surrounding aquifers on the measured borehole flow 3 allow for an arbitrary number n of entry exit points connected to m n far field aquifers and 4 be consistent with the practical limitations of flowmeter measurements such as limits of resolution typical measurement error and finite measurement periods the model is used in three modes 1 a quasi steady pumping mode where there is no ambient flow 2 a steady flow mode where ambient differences in far field water levels drive flow between fracture zones in the borehole and 3 a cross borehole test mode where pumping in an adjacent borehole drives flow in the observation borehole the model gives estimates of transmissivity for any number of fractures in steady or quasi steady flow experiments that agree with straddle packer test data field examples show how these cross borehole type curves can be used to estimate the storage coefficient of fractures and bedding planes and to determine whether fractures intersecting a borehole at different locations are hydraulically connected in the surrounding rock mass

mars atmospheric dynamics as simulated by the nasa ames general circulation model 2 transient baroclinic eddies a large set of experiments performed with the nasa ames mars general circulation model gcm have been analyzed to determine the properties structure and dynamics of the simulated transient baroclinic eddies the mars gcm simulations span a wide range of seasonal dates and dust loadings and include a number of special sensitivity experiments e g with flat topography there is strong transient baroclinic eddy activity in the extratropics of the northern hemisphere during the northern autumn winter and spring seasons the eddy activity remains strong for very large dust loadings though it shifts northward the eastward propagating eddies are characterized by zonal wavenumbers of 1 4 and periods of 2 10 days in several simulations the eddy variance is dominated by a single zonal wavenumber and a narrow range of periods the longer wavenumbers 1 and 2 transient eddies have a very deep vertical structure exhibiting a maximum kinetic energy density at the model top 45 50 km in many of the simulations in a simulation for early northern spring the eddies are quite shallow however the transient eddies generate the bulk of their energy baroclincally via large meridional and vertical heat fluxes at both lower and upper levels this is despite the fact that their vertical structure is typically close to equivalent barotropic above the lowest 10 km the eddies also appear to generate a substantial amount of energy barotropically via large meridional momentum fluxes at both lower and upper levels in the tropics and northern subtropics at upper levels 25 50 km there are strong transient eddy motions with structures resembling those characteristic of inertially unstable modes this eddy activity appears to be a response to the forcing of a region of marginal inertial stability by the extratropical transient baroclinic eddies as the wavenumbers and periods are the same as those in the extratropics a major surprise is the presence of very weak transient eddy activity in a number of the southern winter simulations it appears that this is partly a consequence of the stabilizing effects of the zonally symmetric topography in the gcm but it also must be associated with certain aspects of the zonal mean circulation in southern winter this is indicated by the presence of relatively large amplitude eddies in simulations for early southern autumn and spring and in a southern winter solstice simulation incorporating a different topography derived from the mars digital terrain model this topography differs from that used in most of the gcm simulations in not being characterized by steep symmetric slopes which are stabilizing to baroclinic instability in southern high latitudes it is hypothesized that the very large extent of the southern seasonal polar cap and high elevations in the south both might contribute to weakening the transient eddy activity large zonally symmetric topography in the northern hemisphere of the mars gcm also appears to have a strong impact on the transient eddies acting to increase the dominant zonal wavenumbers and phase speeds the properties of the gcm baroclinic eddies in the northern extratropics are compared in detail with analogous properties inferred from viking lander meteorology observations the gcm eddies are found to be very similar to those observed in most respects a notable exception is that the eddy amplitudes in the highly dusty gcm simulations are much larger than those observed by viking during the 1977 winter solstice dust storm this is almost certainly at least partly due to the relatively small latitudinal expansion of the hadley circulation in the highly dusty gcm experiments

seasonal changes of the baroclinic wave activity in the northern hemisphere of mars simulated with a gcm 1 seasonal changes in baroclinic wave activity during northern autumns ls 195 225 and winters ls 280 300 are studied with a martian general circulation model for the weak dust load the simulated s 2 harmonic with 3 1 sols period dominates near the surface while s 1 5 5 sols period is more prominent at higher altitudes during autumns in winters the s 1 wave has stronger amplitudes and a deep up to 0 1 mb vertical structure these simulations are consistent with observations from mgs we provide a simple explanation for the planetary wave changes in terms of seasonal variations of the background zonal mean fields in particular the observed and simulated significant reduction of the baroclinic wave activity during strong solstitial season dust storms occurs due to the stabilization of the jet stream with respect to baroclinic disturbances and due to the associated weakening of the wave excitation

traveling waves in the martian atmosphere from mgs tes nadir data abstract we have characterized the annual behavior of martian atmospheric traveling waves in the mgs tes data set from the first two martian years of mapping there is a high degree of repeatability between the two years they are dominated by strong low zonal wavenumber waves with high amplitudes near the polar jets strongest in late northern fall and early northern winter the m 1 waves have amplitudes up to about 20 k are vertically extended and occasionally extend even into the tropics periods for m 1 range from 2 5 to 30 sols much weaker waves were identified in the south with amplitudes less than about 3 5 k traveling waves with m 2 and m 3 are also seen but their amplitudes are typically limited to less than 4 k and are generally more confined near the surface in the north they are more evident in fall and spring rather than winter solstice which is clearly dominated by m 1 waves some evidence of storm tracks has been identified in the data with accentuated weather related temperature perturbations near longitudes 200 to 320 e for both the southern and northern hemispheres near latitude 65 at the surface some evidence was also found for a sharpening of longitudinal gradients into what may be frontal systems ep flux divergences show the waves extracting energy from the zonal mean winds when the m 1 waves were strongest decelerations of the zonal jet of order 30 m s sol were measured above 1 scale height the waves extract energy from the jet predominately through barotropic processes but their character is overall mixed barotropic baroclinic inertial instabilities may exist at altitude on the equatorward flanks of the polar jets and marginal stability extends through to the tropics this may explain the coordination of the tropical behavior of the waves with that centered along the polar jet consistent with the ideas expressed in wilson et al 2002 geophys res lett 29 1684 and similar to those in barnes et al 1993 j geophys res 98 3125 3148 throughout the year there exist large regions with the meridional gradient of pv less than zero but they are strongest near winter solstice poleward of the winter jet the regions of instability reach the surface equatorward they do not these regions satisfying a necessary criterion for instability likely explain the genesis of the waves and perhaps also their bimodal character between surface faster waves and altitude slow m 1 waves

carbon dioxide ice clouds snowfalls and baroclinic waves in the northern winter polar atmosphere of mars 1 the formation of co2 ice clouds in the northern winter polar atmosphere of mars and their relation to baroclinic planetary waves which dominate local dynamics are studied using a general circulation model the simulation shows that clouds are formed at altitudes of up to 40 km and their occurrence correlates to a large degree with the cold phases of transient planetary waves ice particles formed up to 20 km can reach the surface in the form of snowfall in certain longitude regions while in others these particles likely sublimate in the lower warmer atmospheric layers the simulation suggests that about a half of the seasonal ice cap is created by co2 snow while the remaining half by direct condensation on the surface thus the occurrences of ice clouds and rates of deposition are closely linked to traveling planetary waves indicating the possibility for the reliable forecasts of co2 snow storms citation kuroda t a s medvedev y kasaba and p hartogh 2013 carbon dioxide ice clouds snowfalls and baroclinic waves in the northern winter polar atmosphere of mars geophys res lett 40 1484 1488 doi 10 1002 grl 50326

the solsticial pause on mars 2 modelling and investigation of causes 2015 elsevier inc the martian solsticial pause presented in a companion paper lewis et al this issue icarus was investigated further through a series of model runs using the uk version of the lmd uk mars global climate model it was found that the pause could not be adequately reproduced if radiatively active water ice clouds were omitted from the model when clouds were used along with a realistic time dependent dust opacity distribution a substantial minimum in near surface transient eddy activity formed around solstice in both hemispheres the net effect of the clouds in the model is by altering the thermal structure of the atmosphere to decrease the vertical shear of the westerly jet near the surface around solstice and thus reduce baroclinic growth rates a similar effect was seen under conditions of large dust loading implying that northern midlatitude eddy activity will tend to become suppressed after a period of intense flushing storm formation around the northern cap edge suppression of baroclinic eddy generation by the barotropic component of the flow and via diabatic eddy dissipation were also investigated as possible mechanisms leading to the formation of the solsticial pause but were found not to make major contributions zonal variations in topography were found to be important as their presence results in weakened transient eddies around winter solstice in both hemispheres through modification of the near surface flow the zonal topographic asymmetry appears to be the primary reason for the weakness of eddy activity in the southern hemisphere relative to the northern hemisphere and the ultimate cause of the solsticial pause in both hemispheres the meridional topographic gradient was found to exert a much weaker influence on near surface transient eddies

maintenance of zonal wind variability associated with the annular mode on mars 1 results from a mars general circulation model mgcm were used to investigate the maintenance of the annular mode in the martian atmosphere analysis of the martian northern winter as represented by the mgcm revealed a prominent transient wave with zonal wave number 1 that had a baroclinic instability structure an empirical orthogonal function eof decomposition showed that the first two modes of the eof contained features of the transient wave with wave number 1 the third eof mode had an annular structure about the martian north pole and an equivalent barotropic structure in the vertical each term in the transformed eulerian mean equation was estimated from the mgcm output to investigate the maintenance of the annular mode wave forcing eliassen palm flux divergence played an important role in maintaining the mode in the wave forcing term contributions from transient baroclinic waves with wave numbers 1 and 2 were important

semiannual oscillations in the atmosphere of mars 1 we report on the first detection of the semiannual oscillation sao in the martian atmosphere the semiannual periodicity is found in the difference between day and night time atmospheric temperatures a good proxy for solar tides measured from mars global surveyor simulations with a general circulation model proved that this modulation of tidal amplitudes is a manifestation of the sao of zonal winds in martian tropics our numerical experiments revealed significant differences in driving mechanisms of the sao between mars and earth on mars unlike on earth equatorial kelvin waves supply only small retrograde torque to the mean circulation instead thermal tides and quasi stationary planetary waves induced by martian topography contribute strongly to the prograde super rotation acceleration the existence of the sao on mars suggests that this phenomenon is not a result of the unique terrestrial environment but a more general consequence of wave mean flow interactions in atmospheres of fast rotating planets

radio occultation measurements of transient eddies in the northern hemisphere of mars 1 we have characterized the behavior of transient eddies in the northern hemisphere of mars through analysis of radio science rs occultation data from mars global surveyor mgs the weather in the lowest scale height above the surface at 55 n 80 n is dominated by shallow eastward moving baroclinic eddies distinguished by their intensity and coherence the vertical structure of these eddies is fully resolved by the rs measurements which also yield unique estimates of the near surface meridional winds implied by geostrophic balance we identified and characterized the most prominent eddies through space time analysis of rs measurements of geopotential height at 610 pa a few kilometers above the surface eddy activity appears as well defined modes with zonal wave numbers 1 3 and variations in the amplitudes of these modes tend to be anticorrelated so that a large amplitude in one mode is often accompanied by a small amplitude in the others the wave number and period of the dominant mode shift at intervals of 30 50 sols eddy winds near the surface vary distinctively with season in response to changes in eddy amplitude and zonal wave number the meridional winds peak sharply in two seasonal windows one in early to middle autumn and the other in middle to late winter separated by a lull around winter solstice comparisons with previous results reveal close connections with the transient eddies observed by the viking landers and with distinctive southward moving frontal dust storms observed by the mgs mars orbiter camera

a global view of gravity waves in the martian atmosphere inferred from a high resolution general circulation model global characteristics of the small scale gravity wave gw field in the martian atmosphere obtained from a high resolution general circulation model gcm are presented for the first time the simulated gw induced temperature variances are in a good agreement with available radio occultation data in the lower atmosphere between 10 and 30 km the model reveals a latitudinal asymmetry with stronger wave generation in the winter hemisphere and two distinctive sources of gws mountainous regions and the meandering winter polar jet orographic gws are filtered while propagating upward and the mesosphere is primarily dominated by harmonics with faster horizontal phase velocities wave fluxes are directed mainly against the local wind gw dissipation in the upper mesosphere generates body forces of tens of m s 1 per martian solar day sol 1 which tend to close the simulated jets the results represent a realistic surrogate for missing observations which can be used for constraining gw parameterizations and validating gcm simulations

wavenumber spectra of planetary scale disturbances in the mars atmosphere abstract wavenumber spectra of the martian atmosphere covering zonal wavenumbers s 1 6 were obtained as a function of latitude and season for the first time from the temperatures measured by the thermal emission spectrometer onboard the mars global surveyor the stationary component tends to peak at s 2 where the martian topography has large amplitude and drops rapidly at higher wavenumbers the transient component in the middle and high latitudes tends to peak at s 1 which is lower than the most unstable wavenumber based on linear theories and exhibits spectral slopes much flatter than the stationary component in the equatorial region the spectra of the transient component are almost flat indicating that the organization of large scale structures is less efficient in this region the spectral shapes are similar between the 0 5 and 2 2 hpa surfaces except that the slopes are slightly steeper at 0 5 than at 2 2 hpa probably due to selective vertical transmission at low wavenumbers the seasonal variation is relatively large in the middle and high latitudes where the maximum power occurs in winter and the minimum occurs in summer with an exception that the transient component is maximum in spring in the southern hemisphere intensification of s 1 transient waves is observed around the period of the initiation of global dust storms

the relative importance of head flux and prior information in hydraulic tomography analysis using cross correlation analysis we demonstrate that flux measurements at observation locations during hydraulic tomography ht surveys carry nonredundant information about heterogeneity that are complementary to head measurements at the same locations we then hypothesize that a joint interpretation of head and flux data even when the same observation network as head has been used can enhance the resolution of ht estimates subsequently we use numerical experiments to test this hypothesis and investigate the impact of flux conditioning and prior information such as correlation lengths and initial mean models i e uniform mean or distributed means on the ht estimates of a nonstationary layered medium we find that the addition of flux conditioning to ht analysis improves the estimates in all of the prior models tested while prior information on geologic structures could be useful its influence on the estimates reduces as more nonredundant data i e flux are used in the ht analysis lastly recommendations for conducting ht surveys and analysis are presented

relationship between frontal dust storms and transient eddy activity in the northern hemisphere of mars as observed by mars global surveyor we have compiled a catalog of frontal dust storms in the northern hemisphere using mars orbiter camera daily global maps spanning 2 3 martian years of mars global surveyor mgs observations from 1999 to 2003 the most vigorous frontal storms that flush dust to the low latitudes occur in early mid fall and mid late winter away from the northern winter solstice while many streaks are observed in the polar hood during the winter solstice period no frontal dust storms are observed in the vicinity of the north polar region we have also analyzed simultaneous mgs thermal emission spectrometer tes temperature data and found statistically significant negative temperature anomalies associated with frontal storms in the lowest scale height of the atmosphere the geographical and seasonal distributions of temperature standard deviations associated with transient variations agree well with the distributions of frontal storms the correlation deteriorates with increasing altitude suggesting that lower level temperature waves are associated with the frontal dust storms specifically eastward traveling m 3 waves with periods of 2 3 sols appear to be closely related to the development of flushing frontal storms

in situ 87sr 86sr of scheelite and calcite reveals proximal and distal fluid rockinteraction during orogenic w au mineralization otago schist new zealand

traveling waves in the northern hemisphere of mars 1 analysis of temperature retrievals from mars global surveyor thermal emission spectrometer data has revealed the presence of regular eastward propagating waves in the northern hemisphere a large amplitude zonal wave 1 with a long 20 sol period is particularly prominent during early winter ls 220 270 after ls 270 a weaker and more rapidly propagating 6 5 sol period zonal wave 1 is dominant these waves have a deep vertical structure 40 km correlated with the axis of the winter hemisphere westerly jet simulations with a mars general circulation model suggest that the fast wave is associated with baroclinic instability due to the strong meridional temperature gradient at the surface and is consistent with surface pressure oscillations seen in viking lander data by contrast the slow wave has the appearance of a large amplitude rossby wave that is coupled with an inertially unstable region in the subtropics

laboratory studies on a new laser doppler velocimeter system for horizontal groundwater velocity measurements in a borehole this paper introduces a new instrument for measuring groundwater velocity in a borehole using a laser doppler velocimeter ldv technique the major improvement of the proposed ldv system is that the probe can be inserted into a borehole that has a minimum diameter of 10 cm and that a disk type rotating grating is used as a frequency shifter for low velocities in order to determine the velocity sign the speed of the glass plate passing through the ldv measurement point is calibrated to demonstrate the accuracy of the new ldv system from a comparison with the true constant speed of the glass plate we confirm that the new ldv system can measure low speeds in the range from 10 5 to 10 2 cm s at a measurement error of less than 8 laboratory experiments were carried out to investigate the performance of the new ldv system for the horizontal velocity measurement of groundwater in a borehole the result obtained by the proposed ldv system shows that the horizontal velocity at the center of an unscreened borehole is 3 times larger than the seepage velocity in a confined aquifer this result agrees with the theoretical solution for groundwater flow in a borehole derived by sano 1983 the validity of the theoretical solution is experimentally verified in the laboratory using the current ldv system although the detectable minimum velocity in a borehole is limited by the velocity fluctuations due to the brownian motion of scattering particles results obtained in the experiments using 0 804 m polystyrene particles show that the ldv system described in this paper can measure with a sufficient accuracy both the magnitude and the direction of groundwater velocity down to 10 4 cm s in a borehole

observations of particle movement in a monitoring well using the colloidal borescope abstract the colloidal borescope consists of a set of lenses and miniature video cameras capable of observing natural particles in monitoring wells based on field observations of these particles it appears possible to measure in situ groundwater velocity in a well bore field observations have shown that directional measurements using the colloidal borescope are generally in good agreement with expected flow directions however the magnitude of flow velocity is higher compared with values based on conventional test methods high relative flow velocities even after correction factors have been applied to compensate for well bore effects are believed to be due to preferential flow zones in the surrounding aquifer low flow zones exhibit swirling multidirectional flow that does not allow for a linear velocity measurement consequently groundwater flow velocities measured by the colloidal borescope in heterogeneous aquifers will be biased toward the maximum velocity values present in the aquifer a series of laboratory experiments was conducted to assess the reliability of the instrument based on this work a seepage velocity correction factor of 1 4 was found for quantifying groundwater seepage velocity in the adjacent aquifer from observations in a well bore laboratory measurements also indicate that preferential flow in the surrounding aquifer dominates flow in the well results of this work suggest the possibility of quantifying higher flow velocities associated with preferential flow zones in the subsurface