structural asymmetry in martian impact craters as an indicator for an impact trajectory abstract impact crater formation is a highly dynamic and complex geological phenomenon methods of structural geology are capable of giving insights into deformation processes that occur during cratering while most deformation observed in craters exhibits a generally radial symmetry recent discoveries of non radial structural elements in the central uplifts of terrestrial craters have led to the suggestion that obliquely impacting projectiles can cause non radial deformation in the central subsurface area of the crater the lack of ejecta blankets as accepted indicators of an oblique impact on earth make it difficult to correlate the observed non radial structures with the impact direction therefore in this study three martian complex impact craters were selected that exhibit an oblique ejecta blanket and layered bedrock in the central uplift the central uplifts were structurally mapped using high resolution imaging science experiment hirise imagery and additional high resolution digital terrain models dtms structural data were evaluated and show a correlation between the orientation of at least two structural criteria and the direction of impact 1 the strike of upturned bedrock layers is on average perpendicular to the impact trajectory and 2 the majority of faults show a preferred trend parallel to the impact trajectory a fourth martian crater was examined as a counterexample which had a radial ejecta blanket and thus no indication of an oblique trajectory strike in this crater showed no preferred orientation these results will help to solidify the suggested correlation between non radial structural features in impact craters and the horizontal component of momentum transferred from an obliquely impacting projectile to the target

heat tracer test in an alluvial aquifer field experiment and inverse modelling abstract using heat as an active tracer for aquifer characterization is a topic of increasing interest in this study we investigate the potential of using heat tracer tests for characterization of a shallow alluvial aquifer a thermal tracer test was conducted in the alluvial aquifer of the meuse river belgium the tracing experiment consisted in simultaneously injecting heated water and a dye tracer in an injection well and monitoring the evolution of groundwater temperature and tracer concentration in the pumping well and in measurement intervals to get insights in the 3d characteristics of the heat transport mechanisms temperature data from a large number of observation wells closely spaced along three transects were used temperature breakthrough curves in observation wells are contrasted with what would be expected in an ideal layered aquifer they reveal strongly unequal lateral and vertical components of the transport mechanisms the observed complex behavior of the heat plume is explained by the groundwater flow gradient on the site and heterogeneities in the hydraulic conductivity field moreover due to high injection temperatures during the field experiment a temperature induced fluid density effect on heat transport occurred by using a flow and heat transport numerical model with variable density coupled with a pilot point approach for inversion of the hydraulic conductivity field the main preferential flow paths were delineated the successful application of a field heat tracer test at this site suggests that heat tracer tests is a promising approach to image hydraulic conductivity field this methodology could be applied in aquifer thermal energy storage ates projects for assessing future efficiency that is strongly linked to the hydraulic conductivity variability in the considered aquifer

application of optical fiber temperature logging an example in a sedimentary environment continuous temperature depth logs especially when recorded in boreholes under thermal equilibrium conditions provide detailed information of the subsurface thermal structure which is necessary for the determination of reliable heat flow and rock thermal properties in conjunction with independent thermal conductivity determinations thermal logging data also allow the separation of heat conduction effects from thermal convection effects by fluid flow driven by various pressure differences such as pore fluid pressure the earth s thermal field is related intimately to geothermal resources and hydrocarbon resources therefore the characterization of temperature in the subsurface and its relationship to lithology is of critical importance

searching for distal ejecta on the craton the sedimentary effects of meteorite impact abstractdistal ejecta from meteorite impacts are rare and hard to spot in the field because of their thinness 5 mm diameter sediments and produce high flow regime bedforms megaripples dunes upper plane beds and possi

groundwater flow conditions in a low angle fracture zone at finnsjon sweden abstract the performance and results of a series of hydraulic head measurements and differently designed tracer tests are described a combined interpretation of the results is utilized to estimate the natural groundwater flow conditions in a low angle major fracture zone zone 2 investigated at the finnsjon study site central eastern sweden the transport of tracer labelled flushing water used during drilling of a cored borehole was utilized to determine hydraulic connections and estimations of hydraulic parameters the breakthrough of tracer was monitored at a distance of 440 m from the injection point with a mean residence time of 37 days in order to determine transport parameters of the fracture zone a tracer test was performed in conjunction with an interference test the hydraulic fracture conductivity flow porosity equivalent fracture width and dispersivity were calculated for three different tracer routes tracer was also used to detect any bypass around the packers during the interference test a series of groundwater flow determinations are also described which used the point dilution technique in packed off borehole sections carried out under natural gradient conditions the groundwater head measurements indicated that a pressure gradient from high to low exists between the adjacent rocks and zone 2 where zone 2 is located closer to the ground surface the opposite situation prevails the upper highly conductive part of the zone was found to have high natural flow rates whereas in the lower highly conductive part the groundwater flow rates were very low close to the rate of molecular diffusion

the sir c x sar synthetic aperture radar system the spaceborne imaging radar c x band synthetic aperture radar sir c x sar was a joint united states german italian space agency imaging radar system successfully flown aboard the shuttle endeavor in april 1994 and again in september october 1994 the multifaceted sir c x sar represents a major technological step forward in radar remote sensing and is the first spaceborne multifrequency polarimetric sar the united states developed sir c operated at l and c band each with quad polarization the sir c antenna was an active phased array with the capability for electronic beam steering and multiple swath width illumination the german italian x sar operated at x band with a single polarization using a slotted waveguide antenna mechanically steerable in elevation sir c and x sar were designed to operate synchronously collecting data over common sites synchronously a total of 143 hours 93 terabits of sar data were recorded on tape

ibn batutah a possible simple impact structure in southeastern libya a remote sensing study abstract the ibn batutah feature is a circular structure centered on 21 34 10 n and 20 50 15 e and located in the prefecture of the hamadat ibn batutah plateau southeastern libya it is a singular geological structure formed in nubian sandstone of most likely early cretaceous age remote sensing investigations based on landsat etm dual band l and c and dual polarization hh and hv radar sir c and srtm data reveal a morphological resemblance of the ibn batuta structure to other confirmed terrestrial simple impact structures the structure is in the form of a circular basin 2 5 km in diameter and 25 m deep surrounded by a low relief rim that rises to within 5 m of the surrounding terrains over much of its extent no endogenic geological processes such as magmatism diapirism karst dissolution and glacial or fluvial erosion can decisively explain the formation of the ibn batutah structure within a large area of flat lying mesozoic sandstones thus this paper proposes that the ibn batutah structure represents a simple impact structure verification of this hypothesis will require collection and analyses of rock samples from in and around the structure although the area is currently almost inaccessible for environmental and security reasons

improved spatial delineation of streambed properties and water fluxes using distributed temperature sensing a new method was developed for analysing and delineating streambed water fluxes flow conditions and hydraulic properties using coiled fibre optic distributed temperature sensing or closely spaced discrete temperature sensors this method allows for a thorough treatment of the spatial information embedded in temperature data by creating a matrix visualization of all possible sensor pairs application of the method to a 5 day field dataset reveals the complexity of shallow streambed thermal regimes to understand how velocity estimates are affected by violations of assumptions of one dimensional saturated homogeneous flow and to aid in the interpretation of field observations the method was also applied to temperature data generated by numerical models of common field conditions horizontal layering presence of lateral flow and variable streambed saturation the results show that each condition creates a distinct signature visible in the triangular matrices the matrices are used to perform a comparison of the behaviour of one dimensional analytical heat tracing models the results show that the amplitude ratio based method of velocity calculation leads to the most reliable estimates the minimum sensor spacing required to obtain reliable velocity estimates with discrete sensors is also investigated using field data the developed method will aid future heat tracing studies by providing a technique for visualizing and comparing results from fibre optic distributed temperature sensing installations and testing the robustness of analytical heat tracing models

characteristics of high resolution hydraulic head profiles and vertical gradients in fractured sedimentary rocks summary accurately identifying the position of vertical hydraulic conductivity k v contrasts is critical to the delineation of hydrogeologic units that serve as the basis for conceptual and numerical models of groundwater flow high resolution head profiles have identified the position and thickness of k v contrasts in clayey aquitards but this potential has not yet been thoroughly evaluated in sedimentary rocks this paper describes an experiment in which head profiles with the highest technically feasible resolution were obtained using westbay multilevel systems mls installed in 15 cored holes at three sedimentary rock research sites with contrasting geologic and flow system conditions mlss were installed to maximum depths between 90 and 260 m with 2 5 monitoring zones per 10 m head profiles were measured over multiyear periods the vertical component of hydraulic gradient i e vertical gradient was calculated for each pair of adjacent monitoring intervals in every mls and then categorized based on its repeatability to facilitate interpretation of k v contrasts and comparisons within boreholes between boreholes at the same site and between sites the head and vertical gradient profiles from all three sites display systematic i e simple geometric shapes defined by repeatable intervals of no to minimal vertical gradient indicating relatively high k v units bounded by shorter depth intervals with large up to 50 m m vertical gradients indicating relatively low k v units the systematic nature of the profiles suggests flow in regular and interconnected fracture networks rather than dominated by a few key fractures with irregular orientations the low k v units were typically thin with their positions and thicknesses not predicted by lithostratigraphy or detailed lithologic geophysical and horizontal hydraulic conductivity data hence the position and thickness of units with contrasting k v would not be evident if mlss with the conventional number of monitoring zones had been used furthermore the detailed profiles can be strongly diagnostic of hydrogeologic unit boundaries or layers and can be used to improve the quantitative assessment of flow system conditions that is foundational to understanding contaminant plume migration

formation of polar cap patches associated with north to south transitions of the interplanetary magnetic field on january 15 1991 the sondrestrom incoherent scatter radar probed the midday high latitude ionosphere to gather evidence for the formation and entry of polar cap patches during the experiment the interplanetary magnetic field imf bz was positive and steady for few hours until 1548 ut when a short negative excursion of bz occurred prior to the bz excursion and when this parameter was directed northward the sondrestrom radar detected a quasi stationary density feature situated near the poleward boundary of the oval convergent electric fields and slightly elevated te values were seen accompanying the f region density feature a numerical model of the high latitude ionosphere that uses a steady north bz heppner and maynard convection pattern suggests that under these imf conditions a tongue of ionization toi can be formed near the midday sector but it is confined to the poleward boundary of the auroral oval it does not traverse into the polar cap this simulated bz northward toi resembles the density feature seen in the radar data prior to the bz negative excursion when the bz value was oriented southward the radar detected the density feature moving poleward and then disappearing to the north of the radar field of view at this time of bz negative the radar data also displayed elevated ti values and a new pattern of line of sight velocities nearly 34 min after the density feature departed from the field of view of the sondrestrom radar the qaanaaq digisonde measured a factor of 2 increase in the of2 values similar enhancements are typically attributed to the passage of a patch we also conducted a numerical simulation of the transit of the density feature from its initial location near the polar cap boundary up to its passage through the qaanaaq station the time that the density feature reaches qaanaaq in our simulations is in good agreement with the actual time that the enhanced patch like number density was observed at qaanaaq the bz switching mechanism does not dispute the validity of other patch formation mechanisms it merely suggests that a bz northward toi can end up as a polar cap patch if a timely reversal of bz occurs

estimation of seepage rates in a losing stream by means of fiber optic high resolution vertical temperature profiling summary vertical temperature profiling in the river beds of losing streams has been shown to be useful in obtaining seepage rates we present a method for high resolution vertical temperature profiling in surface water sediments for detailed quantification of seepage flux over depth and time the method is based on fiber optic distributed temperature sensing in which temperature profiles along an optical fiber are obtained by making use of raman scattering an optical fiber was wrapped around a 2 in pvc tube and installed vertically within the streambed sediment the wrapping transfers the spatial resolution along the fiber of 1 m to a vertical resolution of about 5 mm the high resolution temperature profiler was tested at a losing reach of the swiss prealpine river thur resulting in a 20 day long temperature time series with a temporal resolution of 10 min the time series are analyzed by means of dynamic harmonic regression to obtain the diurnal contributions of the measured time series at all depths and time points the time for the diurnal temperature signal to reach the observation depth and the associated attenuation of the signal are calculated from the phase angles and amplitudes of the diurnal contributions the time shift results in an apparent celerity of diurnal temperature propagation which is converted into an apparent seepage rate by fitting the data to the analytical solution for convective conductive heat transfer in a semi infinite uniform one dimensional domain with a sinusoidal surface temperature the high spatial resolution allows the location of discontinuities in the river bed which would have remained undetected if temperature had been measured only at a few individual depths to be identified this is a particular strength of the fiber optic high resolution temperature profiler the time series also give evidence of sporadic high infiltration rates at times of high water tables

substorm onset by new plasma intrusion themis spacecraft observations 1 recent observations from the 2 d array of high resolution themis all sky imagers asis during the 2008 tail season have shown that the majority of substorm onsets are preceded by equatorward extension of an auroral arc initiated at the poleward boundary of the aurora zone and that the aurora breakup is likely triggered when this precursor arc reaches the onset region these observations were used to suggest that substorm onset is driven by a new population of plasma having lower global entropy content than that of the preexisting plasma intruding into the inner plasma sheet we have taken advantage of conjunctions between the location of the precursor arc observed by the themis asi and themis spacecraft and identified four events where clear signatures of the proposed new plasma intrusion were observed simultaneously in both the magnetotail and ionosphere in two of the events the intrusion plasma was captured more than 10 min before substorm onset in the midtail plasma sheet the intruding plasma is characterized as the reduction of the pressure and entropy parameter associated with more dipolarized magnetic field as well as the enhancement of the duskward electric field and earthward flow in two other events the plasma intrusion was found within 2 min before onset in the inner plasma sheet region r 11 re which is very close to the onset locations these observations are consistent with the proposal that intrusion of low entropy content plasma to the onset region may provide a trigger for substorm onset we also found two plasma intrusion events not associated with substorm onset in the plasma sheet which indicates that the new plasma intrusion is not a sufficient condition for substorm onset we suggest that sufficient pressure and azimuthal pressure gradient buildup in the inner plasma sheet during growth phase should be another necessary condition

overview of results of spaceborne imaging radar c x band synthetic aperture radar sir c x sar the spaceborne imaging radar c x band synthetic aperture radar sir c x sar was launched on the space shuttle endeavour for two ten day missions in the spring and fall of 1994 radar data from these missions are being used to better understand the dynamic global environment during each mission radar images of over 300 sites around the earth were obtained returning over a terabit of data sir c x sar science investigations were focused on quantifying radar s ability to estimate surface properties of importance to understanding global change and focused studies in geology ecology hydrology and oceanography as well as radar calibration and electromagnetic theory studies in addition the second flight featured an interferometry experiment where digital elevation maps were obtained by interfering data from the first and second shuttle flight and from successive days on the second flight sir c x sar data have been used to validate algorithms which produce maps of vegetation type and biomass snow soil and vegetation moisture and the distribution of wetlands developed with earlier aircraft data

inferring transport characteristics in a fractured rock aquifer by combining single hole ground penetrating radar reflection monitoring and tracer test data 1 investigations of solute transport in fractured rock aquifers often rely on tracer test data acquired at a limited number of observation points such data do not by themselves allow detailed assessments of the spreading of the injected tracer plume to better understand the transport behavior in a granitic aquifer we combine tracer test data with single hole ground penetrating radar gpr reflection monitoring data five successful tracer tests were performed under various experimental conditions between two boreholes 6 m apart for each experiment saline tracer was injected into a previously identified packed off transmissive fracture while repeatedly acquiring single hole gpr reflection profiles together with electrical conductivity logs in the pumping borehole by analyzing depth migrated gpr difference images together with tracer breakthrough curves and associated simplified flow and transport modeling we estimate 1 the number the connectivity and the geometry of fractures that contribute to tracer transport 2 the velocity and the mass of tracer that was carried along each flow path and 3 the effective transport parameters of the identified flow paths we find a qualitative agreement when comparing the time evolution of gpr reflectivity strengths at strategic locations in the formation with those arising from simulated transport the discrepancies are on the same order as those between observed and simulated breakthrough curves at the outflow locations the rather subtle and repeatable gpr signals provide useful and complementary information to tracer test data acquired at the outflow locations and may help us to characterize transport phenomena in fractured rock aquifers

actively heated high resolution fiber optic distributed temperature sensing to quantify streambed flow dynamics in zones of strong groundwater upwelling zones of strong groundwater upwelling to streams enhance thermal stability and moderate thermal extremes which is particularly important to aquatic ecosystems in a warming climate passive thermal tracer methods used to quantify vertical upwelling rates rely on downward conduction of surface temperature signals however moderate to high groundwater flux rates 1 5 m d 1 restrict downward propagation of diurnal temperature signals and therefore the applicability of several passive thermal methods active streambed heating from within high resolution fiber optic temperature sensors a hrts has the potential to define multidimensional fluid flux patterns below the extinction depth of surface thermal signals allowing better quantification and separation of local and regional groundwater discharge to demonstrate this concept nine a hrts were emplaced vertically into the streambed in a grid with 0 40 m lateral spacing at a stream with strong upward vertical flux in mashpee massachusetts usa long term 8 9 h heating events were performed to confirm the dominance of vertical flow to the 0 6 m depth well below the extinction of ambient diurnal signals to quantify vertical flux short term heating events 28 min were performed at each a hrts and heat pulse decay over vertical profiles was numerically modeled in radial two dimension 2 d using sutra modeled flux values are similar to those obtained with seepage meters darcy methods and analytical modeling of shallow diurnal signals we also observed repeatable differential heating patterns along the length of vertically oriented sensors that may indicate sediment layering and hyporheic exchange superimposed on regional groundwater discharge

resolving centimeter scale flows in aquifers and their hydrostratigraphic controls 1 the rate of groundwater flow has long been recognized as a critical control on solute transport in the subsurface however information about groundwater flux and its variability in space is rarely available especially at the resolution required for investigations at sites of groundwater contamination recently high resolution information about vertical variations in groundwater flux was obtained using fiber optic distributed temperature sensing technology to monitor the temperature response to active heating in a well a series of vertical thermal profiles were acquired at a 1 4 cm resolution in a sand and gravel aquifer these high resolution profiles which display many of the same general features as hydraulic conductivity k profiles obtained using multiple techniques at the same well provide new insights into site hydrostratigraphy in particular the near continuous profiles reveal the existence of thin zones of relatively high or low velocity that would be difficult to detect using other methods these profiles also demonstrate that vertical variations in k may not be an accurate indicator of vertical variability in groundwater flux in highly heterogeneous aquifers

coherent mesoscale convection patterns during northward interplanetary magnetic field all sky imaging photometer asip and coincident de 2 satellite plasma drift and particle data have been combined to study polar ionospheric convection in the presence of subvisual intensity soft particle excited f region 6300 a sun aligned polar cap arcs coincident de b drift meter data identify these arcs electrodynamically as lines of negative electric field divergence based on conductivities derived from the de b low altitude plasma instrument measured particle fluxes and the measured electric field gradients the divergence of horizontal current across these particle impact excited arcs is in good quantitative agreement with upward birkeland currents carried by the measured particle fluxes although velocity structure can be found without arcs given the asip identified condition of stable weak hundreds of rayleighs 6300 a sun aligned arcs in the polar cap electric field negative divergence is consistently found these arcs of the order of 100 km in width are found by asips in the polar cap about half the time under bz 0 interplanetary magnetic field conditions they are regularly seen by asip data to extend 1000 to over 2000 km in the sunward direction and to persist in time often for over an hour we are thus led to conclude that velocity gradients of this noon midnight elongated scale are typical of bz 0 conditions we further conclude that combined polar asip images and electrostatic potentials calculated along transpolar satellite tracks offer a valuable diagnostic for polar ionospheric convection studies under bz 0 conditions the asip time continuous two dimensionality and the satellite equipotential scaling allow individual snapshots of these polar convection boundaries application here demonstrates highly anisotropic temporally stable convection with greater order than has previously been suspected

subsurface valleys and geoarcheology of the eastern sahara revealed by shuttle radar the shuttle imaging radar sir a carried on the space shuttle columbia in november 1981 penetrated the extremely dry selima sand sheet dunes and drift sand of the eastern sahara revealing previously unknown buried valleys geologic structures and possible stone age occupation sites radar responses from bedrock and gravel surfaces beneath windblown sand several centimeters to possibly meters thick delineate sand and alluvium filled valleys some nearly as wide as the nile valley and perhaps as old as middle tertiary the now vanished major river systems that carved these large valleys probably accomplished most of the erosional stripping of this extraordinarily flat hyperarid region underfit and incised dry wadis many superimposed on the large valleys represent erosion by intermittent running water probably during quaternary pluvials stone age artifacts associated with soils in the alluvium suggest that areas near the wadis may have been sites of early human occupation the presence of old drainage networks beneath the sand sheet provides a geologic explanation for the locations of many playas and present day oases which have been centers of episodic human habitation radar penetration of dry sand and soils varies with the wavelength of the incident signals 24 centimeters for the sir a system incidence angle and the electrical properties of the materials which are largely determined by moisture content the calculated depth of radar penetration of dry sand and granules based on laboratory measurements of the electrical properties of samples from the selima sand sheet is at least 5 meters recent september 1982 field studies in egypt verified sir a signal penetration depths of at least 1 meter in the selima sand sheet and in drift sand and 2 or more meters in sand dunes

substorm triggering by new plasma intrusion themis all sky imager observations 1 a critical long standing problem in substorm research is identification of the sequence of events leading to substorm auroral onset based on event and statistical analysis of themis all sky imager data we show that there is a distinct and repeatable sequence of events leading to onset the sequence having similarities to and important differences from previous ideas the sequence is initiated by a poleward boundary intensification pbi and followed by a north south n s arc moving equatorward toward the onset latitude because of the linkage of fast magnetotail flows to pbis and to n s auroras the results indicate that onset is preceded by enhanced earthward plasma flows associated with enhanced reconnection near the pre existing open closed field line boundary the flows carry new plasma from the open field line region to the plasma sheet the auroral observations indicate that earthward transport of the new plasma leads to a near earth instability and auroral breakup 5 5 min after pbi formation our observations also indicate the importance of region 2 magnetosphere ionosphere electrodynamic coupling which may play an important role in the motion of pre onset auroral forms and determining the local times of onsets furthermore we find motion of the pre onset auroral forms around the harang reversal and along the growth phase arc reflecting a well developed region 2 current system within the duskside convection cell and also a high probability of diffuse appearing aurora occurrence near the onset latitude indicating high plasma pressure along these inner plasma sheet field lines which would drive large region 2 currents

possible connection of polar cap flows to pre and post substorm onset pbis and streamers 1 recent analysis of a short period of observations has led to the hypothesis that enhanced meso scale flows from well within the region of open polar cap field lines may cross the nightside polar cap boundary into the closed field line region and contribute to the triggering of equatorward earthward meso scale flows across the ionospheric equatorial portion of plasma sheet fields lines and lead to pbis and streamers this includes the streamers that have been postulated to bring new plasma equatorward earthward and lead to substorm onset meso scale structure of flow within the polar cap often studied near the dayside polar cap boundary has not previously been generally recognized as significant within the nightside polar cap here we have taken advantage of new capabilities to measure polar cap convection by the resolute bay incoherent scatter radar and the rankin inlet polardarn radar coordinated with themis all sky imager observations to study flow measurements from well within the polar cap to near the polar cap boundary we present evidence that flow structures moving from the polar cap toward the nightside polar cap boundary may be important for triggering the flows that lead to substorm onset streamers the new observations also have given evidence that the flow structures come from deep within the polar cap and have given unexpected evidence that a continuation of flow structures moving from the polar cap toward the nightside polar cap boundary after substorm onset may be important in controlling the poleward expansion and duration of post onset auroral activity

day night coupling by a localized flow channel visualized by polar cap patch propagation we present unique coordinated observations of the dayside auroral oval polar cap and nightside auroral oval by three all sky imagers two super dual auroral radar network superdarn radars and defense meteorological satellite program dmsp 17 this data set revealed that a dayside poleward moving auroral form pmaf evolved into a polar cap airglow patch that propagated across the polar cap and then nightside poleward boundary intensifications pbis superdarn observations detected fast antisunward flows associated with the pmaf and the dmsp satellite whose conjunction occurred within a few minutes after the pmaf initiation measured enhanced low latitude boundary layer precipitation and enhanced plasma density with a strong antisunward flow burst the polar cap patch was spatially and temporally coincident with a localized antisunward flow channel the propagation across the polar cap and the subsequent pbis suggests that the flow channel originated from dayside reconnection and then reached the nightside open closed boundary triggering localized nightside reconnection and flow bursts within the plasma sheet

groundwater flow characterization in a fractured bedrock aquifer using active dts tests in sealed boreholes summary in recent years wireline temperature profiling methods have evolved to offer new insight into fractured rock hydrogeology important advances in wireline temperature logging in boreholes make use of active line source heating alone and then in combination with temporary borehole sealing with flexible impervious fabric liners to eliminate the effects of borehole cross connection and recreate natural flow conditions here a characterization technique was developed based on combining fiber optic distributed temperature sensing dts with active heating within boreholes sealed with flexible borehole liners dts systems provide a temperature profiling method that offers significantly enhanced temporal resolution when compared with conventional wireline trolling based techniques that obtain a temperature depth profile every few hours the ability to rapidly and continuously collect temperature profiles can better our understanding of transient processes allowing for improved identification of hydraulically active fractures and determination of relative rates of groundwater flow the advantage of a sealed borehole environment for dts based investigations is demonstrated through a comparison of dts data from open and lined conditions for the same borehole evidence for many depth discrete active groundwater flow features under natural gradient conditions using active dts heat pulse testing is presented along with high resolution geologic and geophysical logging and hydraulic datasets implications for field implementation are discussed

wind streaks on venus clues to atmospheric circulation magellan images reveal surface features on venus attributed to wind processes sand dunes wind sculpted hills and more than 5830 wind streaks have been identified the streaks serve as local wind vanes representing wind direction at the time of streak formation and allowing the first global mapping of near surface wind patterns on venus wind streaks are oriented both toward the equator and toward the west when streaks associated with local transient events such as impact cratering are deleted the westward component is mostly lost but the equatorward component remains this pattern is consistent with a hadley circulation of the lower atmosphere

interpreting tracer breakthrough tailing from different forced gradient tracer experiment configurations in fractured bedrock 1 conceptual and mathematical models are presented that explain tracer breakthrough tailing in the absence of significant matrix diffusion model predictions are compared to field results from radially convergent weak dipole and push pull tracer experiments conducted in a saturated crystalline bedrock the models are based upon the assumption that flow is highly channelized that the mass of tracer in a channel is proportional to the cube of the mean channel aperture and the mean transport time in the channel is related to the square of the mean channel aperture these models predict the consistent 2 straight line power law slope observed in breakthrough from radially convergent and weak dipole tracer experiments and the variable straight line power law slope observed in push pull tracer experiments with varying injection volumes the power law breakthrough slope is predicted in the absence of matrix diffusion a comparison of tracer experiments in which the flow field was reversed to those in which it was not indicates that the apparent dispersion in the breakthrough curve is partially reversible we hypothesize that the observed breakthrough tailing is due to a combination of local hydrodynamic dispersion which always increases in the direction of fluid velocity and heterogeneous advection which is partially reversed when the flow field is reversed in spite of our attempt to account for heterogeneous advection using a multipath approach a much smaller estimate of hydrodynamic dispersivity was obtained from push pull experiments than from radially convergent or weak dipole experiments these results suggest that although we can explain breakthrough tailing as an advective phenomenon we cannot ignore the relationship between hydrodynamic dispersion and flow field geometry at this site the design of the tracer experiment can severely impact the estimation of hydrodynamic dispersion and matrix diffusion in highly heterogeneous geologic media

substorm onset and expansion phase intensification precursors seen in polar cap patches and arcs 1 localized transient polar cap flows impinging on the poleward boundary of the nightside auroral oval have been suggested to precede poleward boundary intensifications pbis which are often followed by auroral streamers some of which propagate equatorward and appear to lead to substorm auroral onset while echo coverage often limits radar flow measurements imaging of polar cap patches and arcs has the potential to monitor localized polar cap flows by tracing emission structures previously associated with enhanced flows over long distances we use such imaging to examine if polar cap patches and arcs moving over large distances can be seen as possible precursors to presubstorm onset pbis we find evidence that such features which are longitudinally narrow propagate from the dayside polar region toward the nightside polar cap boundary prior to pre onset pbis this sequence indicates that transient activity in the dayside polar region may initiate polar cap patches and arcs that propagate across the polar cap and are followed by pre onset pbis furthermore we find evidence that expansion phase active aurora expanded poleward soon after additional polar cap patches and arcs reached close to the nightside polar cap boundary the expansion phase auroral activity significantly weakened when polar cap patches arcs disappeared our findings suggest that plasma transport originating from the dayside and reaching the nightside open closed boundary may trigger in plasma sheet flow bursts and play a crucial role in pre and post onset auroral activity polar cap imaging offers the possibility for monitoring such localized transient plasma transport over large distances

an active heat tracer experiment to determine groundwater velocities using fiber optic cables installed with direct push equipment a new approach is developed to insert fiber optic cables vertically into the ground with direct push equipment groundwater temperatures may be measured along the cables with high spatial and temporal resolution using a distributed temperature sensing system the cables may be inserted up to depths of tens of meters in unconsolidated sedimentary aquifers the main advantages of the method are that the cables are in direct contact with the aquifer material the disturbance of the aquifer is minor and no borehole is needed this cost effective approach may be applied to both passive and active heat tracer experiments an active heat tracer experiment was conducted to estimate horizontal groundwater velocities in a managed aquifer recharge system in the netherlands six fiber optic cables and a separate heating cable were inserted with a 1 m spacing at the surface the heating cable was turned on for 4 days and temperatures were measured during both heating and cooling of the aquifer temperature measurements at the heating cable alone were used to estimate the magnitude of the groundwater velocity and the thermal conductivity of the solids the direction of the velocity and heat capacity of the solids were estimated by including temperature measurements at the other fiber optic cables in the analysis the latter analysis suffered from the fact that the cables were not inserted exactly vertical the three dimensional position of the fiber optic cables must be measured for future active heat tracer experiments

severe and localized gnss scintillation at the poleward edge of the nightside auroral oval during intense substorm aurora in this paper we study how gps glonass and galileo navigation signals are compromised by strong irregularities causing severe phase scintillation 1 in the nightside high latitude ionosphere during a substorm on 3 november 2013 substorm onset and a later intensification coincided with polar cap patches entering the auroral oval to become auroral blobs using global navigation satellite systems gnss receivers and optical data we show severe scintillation driven by intense auroral emissions in the line of sight between the receiver and the satellites during substorm expansion the area of scintillation followed the intense poleward edge of the auroral oval the intense auroral emissions were colocated with polar cap patches blobs the patches did not contain strong irregularities neither before entering the auroral oval nor after the aurora had faded signals from all three gnss constellations were similarly affected by the irregularities furthermore two receivers spaced around 120km apart reported highly different scintillation impacts with strong scintillation on half of the satellites in one receiver and no scintillation in the other this shows that areas of severe irregularities in the nightside ionosphere can be highly localized amplitude scintillations were low throughout the entire interval

on the importance of interplanetary magnetic field by on polar cap patch formation 1 a number of poleward moving events were observed between 1130 and 1300 ut on 11 february 2004 during periods of southward interplanetary magnetic field imf while the steerable antenna of the european incoherent scatter eiscat svalbard radar esr and the tromso vhf radar pointed nearly northward at low elevation in this interval simultaneous superdarn cutlass finland radar measurements showed poleward moving radar aurora forms pmrafs which appeared very similar to the density enhancements observed by the esr northward pointing antenna these events appeared quasiperiodically with a period of about 10 min comparing the observations from the above three radars it is inferred that there is an almost one to one correspondence between the poleward moving plasma concentration enhancements pmpces observed by the esr and the vhf radar and the pmrafs measured by the cutlass finland radar these observations are consistent with the interpretation that the polar cap patch material was generated by photoionization at subauroral latitudes and that the plasma was structured by bursts of magnetopause reconnection giving access to the polar cap there is clear evidence that plasma structuring into patches was dependent on the variability in imf by the duration of these events implies that the average evolution time of the newly opened flux tubes from the subauroral region to the polar cap was about 33 min

bias in groundwater samples caused by wellbore flow design of physical installations and sampling procedures for ground water monitoring networks particularly for detection and analysis of possible contaminants is a topic of great scientific and practical interest at the present time recent practice in the design of monitoring networks associated with known contaminant sources sometimes includes an array of monitoring wells with long well screens up to 50 feet or more numerical experiments with a detailed three dimensional ground water flow model indicate that significant wellbore flow can occur in contaminant monitoring wells with long well screens that are embedded in homogeneous aquifers with very small vertical head differences in the aquifer this short circuiting of flow through boreholes should exist at some level on all scales consideration of the general flow pattern within the borehole the flow pattern in the aquifer adjacent to the borehole and the process of obtaining water samples from the borehole suggests that in many situations

thermal attenuation and lag time in fractured rock theory and field measurements from joint heat and solute tracer tests the modelling and prediction of heat transfer in fractured media is particularly challenging as hydraulic and transport properties depend on a multiscale structure that is difficult to resolve in addition to advection and dispersion heat transfer is also impacted by thermal attenuation and lag time which results from fracture matrix thermal exchanges here we derive analytical expressions for thermal lag time and attenuation coefficient in fractured media which quantify the effect of fracture geometry on these key factors we use the developed expressions to interpret the results of single well thermal tracer tests performed in a crystalline rock aquifer at the experimental site of ploemeur h observatory network thermal breakthrough was monitored with fiber optic distributed temperature sensing fo dts which allows temperature monitoring at high spatial and temporal resolution the observed thermal response departs from the conventional parallel plate fracture model but is consistent with a channel model representing highly channelized fracture flow these findings which point to a strong reduction of fracture matrix exchange by flow channeling show the impact of fracture geometry on heat recovery in geothermal systems this study also highlights the advantages to conduct both thermal and solute tracer tests to infer fracture aperture and geometry

localized polar cap precipitation in association with nonstorm time airglow patches although airglow patches are traditionally regarded as high density plasma unrelated to local precipitation past observations were limited to disturbed conditions recent non storm time observations show patches to be associated with ionospheric flow channels and localized field aligned currents we examine whether non storm time patches are related also to polar cap precipitation using fast imager conjunctions we have identified localized precipitation that is enhanced within patches in comparison to the weak polar rain outside patches the precipitation consists of structured or diffuse soft electron fluxes while the latter resembles polar rain only with higher fluxes the former consists of discrete fluxes enhanced by 1 2 orders of magnitude from several to several hundred ev therefore patches should be regarded as part of a localized magnetosphere ionosphere coupling system along open magnetic field lines and their transpolar evolution as a reflection of mesoscale magnetotail lobe processes the precipitation is not a major contributor to patch ionization

investigation of shuttle radar topography mission data of the possible impact structure at serra da cangalha brazil the serra da cangalha crater structure in northeast brazil 13 km in diameter has long been widely considered to be a confirmed impact structure based on reports of shatter cone findings only very limited field work has been carried out at this crater structure landsat thematic mapper tm and shuttle radar topography mission srtm data sets for the region around this crater structure are compared here with regard to their suitability to determine first order structural detail of impact crater structures the srtm data provide very detailed information regarding drainage patterns and topography a pronounced central ring of up to 300 m elevation above the surrounding area two comparatively subdued intermediate rings of 6 and 10 5 km diameter respectively and the broad complex crater rim of up to 100 m elevation can be distinguished in the serra da cangalha data the maximum cratering related regional deformation radial and concentric features seems to be limited to a radial distance of 16 18 km from the center of the structure a first comparison of macrostructural information from several impact structures with that from serra da cangalha does not yield firm trends but the database is still very small at this stage the varied nature of the target geology strongly influences the development of structural features in any impact event

wolfe creek crater a continuous sediment fill in the australian arid zone records changes in monsoon strength through the late quaternary abstract a bolide that impacted nw australia during the late quaternary left a circular depression more than 100 m deep and nearly a kilometer in diameter with a crater rim 30 m above the regional terrain the resultant crater is a window into the regional water table the surface of the contemporary central pan is 25 m below the adjacent terrain coincident with the late holocene regional water table modified by local evaporative processes shielded from aeolian deflation by the crater rim the central depression has slowly filled with dust sand and chemical precipitates estimated to be 20 100 m thick based on geophysical surveys one of the few continuous depocenters in the australian arid zone the nature of the crater s sediment fill is controlled by interactions between the water table primarily in response to changes in summer monsoon rain changes in the delivery of sand and dust to the crater by the prevailing easterly winds and the level of the sedimentary fill surface optically stimulated luminescence osl and 14c dates constrain an age model indicating the upper 10 m of sediment fill recovered from the central pan span the past 60 ka the lowest 3 m consist of clayey sand deposited in perennial water during marine isotope stage mis 3 the water table subsequently dropped rapidly 35 ka and remained more than 7 m below the late holocene level through most of mis 2 during which 2 m of sandy clay was deposited on a dry crater floor confirming a dry and dusty last glacial maximum lgm climate by 14 ka a rising water table intersected the crater surface modifying the upper 50 cm of lgm sediment and syndepositionally modifying another 60 cm of subsequent sandy clay deposition aeolian sediment delivery effectively ceased 13 ka and the upper 4 8 m is a gypsum dominated precipitate which initially accumulated rapidly before equilibrating with the late holocene water table shortly after 6 ka lacustrine carbonate encrustations on rocks at the base of the crater wall and 4 m above the central pan with 14c ages 40 ka document a time when regional groundwater maintained a water body in the crater 3 5 4 5 m above the modern groundwater level the crater wall deflected the prevailing easterly winds creating a horseshoe dune extending westerly on both sides of the crater with an extension rate of 35 m ka 1 an augered hole through the northern dune revealed 10 m of sediment overlying ferricrete the lowest meter is a mixture of broken ferricrete and sand that we interpret to be debris from the bolide impact three osl dates through the dune project an age for the debris dune contact of 120 10 ka changes in physical properties and bulk sediment 13c through the 9 m of aeolian sediment indicate the lowest 1 8 m was deposited during mis 5 120 85 ka under a uniformly wetter climate than present the overlying 4 3 m of sediment was deposited between 85 and 14 ka mis 4 3 2 and exhibits transitional characteristics between the lower unit and the upper 3 8 of sand which was deposited primarily during the holocene large changes in the regional water table occurred over the past 60 ka including an lgm water table persistently 7 m lower than late holocene levels and 3 5 4 5 m higher prior to 40 ka plausibly in mis 5 indicative of a stronger australian summer monsoon than at any time subsequently age models and sediment properties from the two sedimentary records indicate the crater was formed 60 ka and most likely 120 ka more recently than previous estimates

combining fiber optic dts cross hole ert and time lapse induction logging to characterize and monitor a coastal aquifer the characterization of saline water intrusion swi and its hydrodynamics is a key issue to understand submarine groundwater discharge sgd and manage groundwater resources in coastal areas to test and compare different methods of characterization and monitoring a new experimental site has been constructed in a coastal alluvial aquifer north of barcelona city catalonia spain the site is located between 30 and 90 m from the seashore and comprises 16 shallow piezometers organized in nests of three with depths ranging between 15 and 25 m and 4 solitary piezometers the objective of this paper is to combine different recently developed monitoring techniques to evaluate temporal variations in the aquifer hydrodynamics of the site at different spatial scales before and after the dry season of 2015 at the site scale fibre optic distributed temperature sensing fo dts for the first time applied to study swi and cross hole electrical resistivity tomography chert has been applied at the meter borehole scale electrical conductivity of the formation has been applied not only in a repeated manner time lapse but also for the first time at relatively high frequency 1 sample every 10 min chert has provided a better characterization of the seawater intrusion than electrical conductivity data obtained from piezometers the combination of techniques has allowed improving the understanding of the system by 1 characterizing the extent and shape of swi 2 differentiating two different dynamics in the aquifer and 3 identifying preferential flow paths over different time and spatial intervals future challenges and the application of these techniques in other areas are also discussed

aeolian features on venus preliminary magellan results magellan synthetic aperture radar data reveal numerous surface features that are attributed to aeolian or wind processes wind streaks are the most common aeolian feature they consist of radar backscatter patterns that are high low or mixed in relation to the surface on which they occur a data base of more than 3400 wind streaks shows that low backscatter linear forms long narrow streaks are the most common and that most streaks occur between 17 s to 30 s and 5 n to 53 n on smooth plains moreover most streaks are associated with deposits from certain impact craters and some tectonically deformed terrains we infer that both of these geological settings provide fine particulate material that can be entrained by the low velocity winds on venus turbulence and wind patterns generated by the topographic features with which many streaks are associated can account for differences in particle distributions and in the patterns of the wind streaks thus some high backscatter streaks are considered to be zones that are swept free of sedimentary particles to expose rough bedrock other high backscatter streaks may be lag deposits of dense materials from which low density grains have been removed dense materials such as ilmenite or pyrite have dielectric properties that would produce high backscatter patterns wind streaks generally occur on slopes 2 and tend to be oriented toward the equator consistent with the hadley model of atmospheric circulation in addition to wind streaks other aeolian features on venus include yardangs and dune fields the aglaonice dune field centered at 25 s 340 e covers 1290 km 2 and is located in an ejecta flow channel from the aglaonice impact crater the meshkenet dune field located at 67 n 90 e covers 17 120 km 2 in a valley between ishtar terra and meshkenet tessera wind streaks associated with both dune fields suggest that the dunes are of transverse forms in which the dune crests are perpendicular to the prevailing winds dunes on venus signal the presence of sand size 60 to 2 000 m grains the possible yardangs are found at 9 n 60 5 e about 300 km southeast of the crater mead although most aeolian features are concentrated in smooth plains near the equator the occurrence of wind streaks is widespread and some have been found at all latitudes and elevations they demonstrate that aeolian processes operate widely on venus the intensity of wind erosion and deposits however varies with locality and is dependent on the wind regime and supply of particles

in situ measurement of a newly created polar cap patch 1 the investigation of cusp irregularities 2 sounding rocket was launched 5 december 2008 at 1035 ut we present an overview of the associated solar wind and auroral conditions and we look in detail at the relationship between poleward moving auroral forms pmafs and the creation of polar cap patches using ground based optical and radar data as well as in situ data from the rocket payload the solar wind was found to be dominated by a stable interplanetary magnetic field imf bz 0 situation the aurora was characterized by a series of pmafs throughout the period of interest associated with each pmaf were polar cap patches seen to emerge from the most poleward location of the pmafs on the basis of the available data we present a conceptual model explaining the creation of the polar cap patches under the given solar wind and ionospheric conditions

enhanced detection of hydraulically active fractures by temperature profiling in lined heated bedrock boreholes summary the effectiveness of borehole profiling using a temperature probe for identifying hydraulically active fractures in rock has improved due to the combination of two advances improved temperature sensors with resolution on the order of 0 001 c and temperature profiling within water inflated flexible impermeable liners used to temporarily seal boreholes from hydraulic cross connection the open hole cross connection effects dissipate after inflation so that both the groundwater flow regime and the temperature distribution return to the ambient background condition this paper introduces a third advancement the use of an electrical heating cable that quickly increases the temperature of the entire static water column within the lined hole and thus places the entire borehole and its immediate vicinity into thermal disequilibrium with the broader rock mass after heating for 4 6 h profiling is conducted several times over a 24 h period as the temperature returns to background conditions this procedure referred to as the active line source als method offers two key improvements over prior methods first there is no depth limit for detection of fractures with flow second both identification and qualitative comparison of evidence for ambient groundwater flow in fractures is improved throughout the entire test interval the benefits of the als method are demonstrated by comparing results from two boreholes tested to depths of 90 and 120 m in a dolostone aquifer used for municipal water supply and in which most groundwater flow occurs in fractures temperature logging in the lined holes shows many fractures in the heterothermic zone both with and without heating but only the als method shows many hydraulically active fractures in the deeper homothermic portion of the hole the identification of discrete groundwater flow at many depths is supported by additional evidence concerning fracture occurrence including continuous core visual inspection acoustic televiewer logs and tests for hydraulic conductivity using straddle packers as well as rock core voc data where available that show deep penetration and many migration pathways confidence in the use of temperature profiles and the conceptual model is provided by numerical simulation and the demonstrated reproducibility of the evolution of the temperature signal measured in the lined holes with and without heating this approach for using temperature profiling in lined holes with heating is a practical advance in fractured rock hydrogeology because the liners are readily available the equipment needed for heating is low cost and rugged and the time needed to obtain the profiles is not excessive for most projects

comparison of remote sensing observations of planetary wind streaks abstract wind streaks are common aeolian features observed on terrestrial planets they were first identified on mars thus the associated terminology is based on mars related observations usually describing surface patterns with distinct albedos however terms related to reflected tones are only relevant to past knowledge for mars and not necessarily suitable for description of radar visible streaks located on venus titan or earth furthermore the sensor type used to observe wind streaks can influence the subsequent data analysis the purpose of this study was to examine the effects of sensor type on wind streak identification and interpretation six case studies featuring wind streaks on earth were performed using imaging by both radar and optical sensors the results indicate that wind streak identification is constrained to a specific combination of sensor settings appropriate for the local surface properties only half the optically visible wind streaks considered in this study were also radar visible but all the wind streaks observable in the radar images also appeared in the optical images furthermore bright and dark reflectance and backscatter are relative terms and should be used with caution these results suggest that the venusian wind streak database is most likely far from complete and that many more streaks exist

two dimensional ionospheric flow pattern associated with auroral streamers 1 we present direct two dimensional flow observations and auroral images from the super dual auroral radar network superdarn radar and wideband imaging camera onboard imager for magnetopause to aurora global exploration image wic imager to investigate the ionospheric flow pattern associated with auroral streamers for four events using the superdarn observations allows us to observe the flow associated with the streamers in the context of the larger scale background convection for all four cases studied streamers developed from preexisting east west ew arcs that initiated from bead like or small scale auroral intensifications around the auroral poleward boundary we find a vortex like flow pattern with clockwise sense surrounding both the initial auroral forms and the ensuing streamers we also found in three cases signatures of flow bifurcations at the equatorward end of the streamers which suggests a double vortex like flow pattern with the counterclockwise vortex east of the clockwise one our results are consistent with the double vortex flow structure that results from interchange convection associated with a plasma sheet bubble predicted by different numerical simulations this supports several previous studies and offers more complete observational evidence that the observed flow pattern may be the ionospheric manifestation of interchange instability in the plasma sheet

polar cap precursor of nightside auroral oval intensifications using polar cap arcs recent radar and optical observations suggested that localized fast flows in the polar cap precede disturbances within the nightside auroral oval however how commonly this connection occurs has been difficult to examine due to limited coverage of radar flow measurements and diffuse and dim nature of airglow patches polar cap arcs are also associated with fast flows in the polar cap and appear much brighter than patches allowing evaluation of the interaction between polar cap structures and nightside aurora more definitively we have surveyed data during six winter seasons and selected quasi steady polar cap arcs lasting 1 h thirty four arcs are found and for the majority 85 of them as they extend equatorward from high latitude their contact with the nightside auroral poleward boundary is associated with new and substantial intensifications within the oval these intensifications are localized 1 h magnetic local time mlt and statistically occur within 10 min and 1 h mlt from the contact they appear as poleward boundary intensifications in a thick auroral oval or an intensification of the only resolvable arc within a thin oval and the latter can also exhibit substantial poleward expansion when radar echoes are available they corroborate the association of polar cap arcs with localized enhanced antisunward flows that the observed oval intensifications are major disturbances that only occur after the impingement of polar cap arcs and near the contact longitude suggest that they are triggered by localized fast flows coming from deep in the polar cap

dynamic temporal evolution of polar cap tongue of ionization during magnetic storm 1 during a magnetic storm on 14 16 december 2006 a polar cap tongue of ionization toi was detected by an all sky imager asi at resolute bay canada 74 73 n 265 07 e we investigate the temporal evolution and spatial structure of the toi in detail by combining the optical data with other observations e g solar wind gps total electron content superdarn and dmsp and noaa poes satellites the toi was observed as a bright and elongated 630 nm airglow plume for 4 h during the main phase of the storm this interval corresponded to a period of prolonged stable large amplitude southward imf during a coronal mass ejection cme one to one and a half hours before the appearance of toi the polar cap boundary expanded rapidly far equatorward and a positive ionospheric storm occurred this implies that both the expansion of the high latitude plasma convection and build up of the source plasma in the midlatitudes are necessary conditions for the formation of a toi because both of them were triggered by a major southward turning of the imf the prolonged large amplitude southward imf orientation in the trailing part of the cme was primarily responsible for the generation of toi after its appearance the toi exhibited dynamic motion in the dawn to dusk direction simultaneous superdarn data suggest that a longitudinal progression of subauroral polarization stream controlled this dynamic motion the optical toi was found to be a continuous stream elongated in the noon midnight direction although it contained some mesoscale patterns absence of large scale temporal changes in the cusp plasma flow during the stable imf period allowed the toi to remain continuous without being broken into polar cap patches the mesoscale structures within the toi were probably produced by small scale velocity fluctuations in the cusp plasma flow the toi as visualized with the all sky airglow imager was found to be much more dynamic and much more complicated than we ever thought the current study indicates that such a behavior of the toi was presumably caused by a combination of temporal variations in the global scale plasma circulation system expansion and contraction of the polar cap area and plasma density changes in the dayside low to midlatitudes

thermal conductivity from core and well log data abstract the relationships between thermal conductivity and other petrophysical properties have been analysed for a borehole drilled in a tertiary flysch sequence we establish equations that permit us to predict rock thermal conductivity from logging data a regression analysis of thermal conductivity bulk density and sonic velocity yields thermal conductivity with an average accuracy of better than 0 2 w m k 1 as a second step logging data are used to compute a lithological depth profile which in turn is used to calculate a thermal conductivity profile from a comparison of the conductivity depth profile and the laboratory data it can be concluded that thermal conductivity can be computed with an accuracy of less than 0 3 w m k 1 from conventional wireline data the comparison of two different models shows that this approach can be practical even if old and incomplete logging data are used the results can be used to infer thermal conductivity for boreholes without appropriate core data that are drilled in a similar geological setting

detailed hydraulic head profiles as essential data for defining hydrogeologic units in layered fractured sedimentary rock this paper describes a study in southern wisconsin where vertical hydraulic head profiles measured in exceptional detail provided the key data for defining hydrogeologic units hgus in a layered sequence of sandstone siltstone shale and dolostone the most important data were obtained from corehole mp 6 which was cored 131 m into bedrock and instrumented using a westbay multilevel system with 36 depth discrete monitoring intervals the resulting head profile is consistant over time and shows eight distinct inflections in hydraulic head several of the inflections occur between adjacent permeable units and are likely due to poor vertical connectivity of fracture sets rather than distinct lower permeability layers or aquitards in the conventional sense no other type of data was capable of identifying the position of such distinct hydrogeologic features these zones of abrupt head loss provide the primary dataset for delineation of eleven hgus at mp 6 and are supported by less detailed head profiles at other locations although the detailed head profiles are essential core logs and geophysical logs from other boreholes are nessessary to fully establish the lateral continuity of the hgus

space shuttle observations of terrestrial impact structures using sir c and x sar radars ten terrestrial impact structures were imaged during two flights of the 1994 space radar laboratory srl experiment these craters include wolf creek australia roter kamm namibia zhamanshin kazakhstan b p and oasis libya aorounga chad amguid algeria and spider connolly basin and henbury australia srl contained two co registered instruments the united states sir c polarimetric radar system operating in l band 24 cm and c band 5 6 cm and the joint german italian x sar vertically polarized radar operating in x band 3 cm comparisons show srl images to be complementary to or in some cases superior to corresponding optical images for evaluating size location and relative age of impact features regardless of wavelength or polarization craters with significant relief appear prominently on radar as a result of slope and roughness effects in desert regions longer wavelengths penetrate dry sand mantles to reveal hidden crater dimensions or associated buried landforms radar polarities and wavelengths are particularly sensitive to vegetation surface roughness and soil moisture or electrical properties in the more temperate environments of kazakhstan and australia srl images show detailed stream patterns that reveal the location and structure of otherwise obscured impact features

impact crater related surficial deposits on venus multipolarization radar observations with arecibo 1 the distribution of surficial deposits in the vicinity of impact craters on venus was studied using measurements of the polarization properties of the reflected radar wave subsurface scattering of an incident circularly polarized radar signal results in a linearly polarized component in the radar echo due to the differing transmission coefficients at a smooth at wavelength scales atmosphere surface boundary for the horizontal h and vertical v linearly polarized components of the incident wave arecibo 12 6 cm wavelength radar observations in 1999 and 2001 provided images of the surface of venus in the full stokes polarization parameters of the reflected echo from which images in the degree of linear polarization were derived these images show that substantial areas of sedna guinevere and lavinia planitias return a radar echo with a significant degree of linear polarization indicating that mantling deposits may be relatively widespread on the plains of venus the areas showing linear polarization enhancements are strongly correlated with topographic features primarily impact craters dome fields and windblown deposits including dune fields a strong linearly polarized echo component 10 40 linear polarization is found from regions near 45 impact craters including 5 parabolas these linear polarization features typically correspond to diffuse higher backscatter cross section bright regions in magellan images the linearly polarized component in these regions is attributed to subsurface echoes from a mantled substrate or from buried rocks

field validation of thermal tracer tomography for reconstruction of aquifer heterogeneity in the summer of 2015 a series of thermal tracer tests were conducted at the widen field site in northeast switzerland to validate travel time based thermal tracer tomography for reconstruction of aquifer heterogeneity repeated thermal tracer tests and distributed temperature observations were used to obtain a multisource multireceiver tomographic experimental setup after creating forced hydraulic gradient conditions heated water was injected as a pulse temperature signal via a double packer system with this solution long temperature recovery periods were not required between the repeated injections at the expense of smaller observed temperatures the recorded temperature breakthrough curves delivered a tomographic travel time data set that was inverted assuming advection dominated condition the obtained hydraulic conductivity tomogram for a small aquifer profile is validated with the results of the findings from previous field investigations at the same site the reconstructed profile confirms the presence of a thin sand layer with low permeability and reveals a previously unknown low permeable zone close to the bottom of the aquifer the inverted hydraulic conductivity values also correspond with those from previous tracer tests thus the results of this study demonstrate the potential of thermal tracer tomography for resolving structures and transport characteristics of heterogeneous aquifers

investigation of aquifer estuary interaction using wavelet analysis of fiber optic temperature data fiber optic distributed temperature sensing fodts provides sub minute temporal and meter scale spatial resolution over kilometer long cables compared to conventional thermistor or thermocouple based technologies which measure temperature at discrete and commonly sparse locations fodts offers nearly continuous spatial coverage thus providing hydrologic information at spatiotemporal scales previously impossible large and information rich fodts datasets however pose challenges for data exploration and analysis to date fodts analyses have focused on time series variance as the means to discriminate between hydrologic phenomena here we demonstrate the continuous wavelet transform cwt and cross wavelet transform xwt to analyze fodts in the context of related hydrologic time series we apply the cwt and xwt to data from waquoit bay massachusetts to identify the location and timing of tidal pumping of submarine groundwater

motion of polar cap patches a statistical study with all sky airglow imager at resolute bay canada 1 a highly sensitive all sky airglow imager part of the optical mesosphere thermosphere imagers omtis has been operating for 3 years at resolute bay canada geographic latitude 74 7 n geomagnetic latitude 82 9 n since january 2005 one of its major applications is the observation of polar cap patches polar cap patches are generated in the vicinity of the cusp during southward interplanetary magnetic field imf conditions and they exhibit dynamic movement possibly in association with the changes in the imf orientation in order to determine how their motions are controlled by the upstream imf conditions we applied a motion tracking algorithm that was based on two dimensional cross correlation analysis to consecutive images obtained from january 2005 to december 2007 by the all sky airglow imager at resolute bay we identified and extracted 561 individual patches and then carried out a statistical study of their motion it is demonstrated that the speed of patches is primarily controlled by the imf bz furthermore the dawn dusk component of the patch drift velocities is well correlated with the imf by which is in good agreement with the published by dependence of the nightside polar cap convection this enables us to monitor the plasma convection within the polar cap by using polar cap patches as tracers

unsolved problems mesoscale polar cap flow channels structure propagation and effects on space weather disturbances recent evidence indicates that the magnetosphere ionosphere system is frequently driven by dynamic mesoscale flow structures that are first seen near the dayside cusps move across the open field line regions of the polar caps and then enter the plasma sheet where they lead to a large variety of space weather disturbances it will be important to uncover the features of these flow enhancements including their structure how they propagate across the polar cap and what controls their dynamic effects after reaching the nightside plasma sheet

estimating drift velocity of polar cap patches with all sky airglow imager at resolute bay canada 1 highly sensitive all sky airglow imager has been operative at resolute bay canada 74 73 n 265 07 e aacgm latitude 82 9 since january 2005 we present as a first result from the imager an event of polar cap patches drifting anti sunward during the southward imf conditions magnitude and direction of patch drift velocities are computed with a temporal resolution of 2 min by using the newly developed patch tracking algorithm based on 2d cross correlation analysis it is well visualized that the patches change their moving speed and direction drastically in a short time scale a few minutes speed of the patch is primally controlled by the imf bz dawn dusk component of the patch drift velocities is well correlated with the imf by in agreement with published by dependence of the nightside polar cap convection however response of the patch drift direction to the imf by is found to be much slower 20 min than that of the drift speed to the imf bz almost instantaneous

characterizing groundwater flow and heat transport in fractured rock using fiber optic distributed temperature sensing 1 we show how fully distributed space time measurements with fiber optic distributed temperature sensing fo dts can be used to investigate groundwater flow and heat transport in fractured media heat injection experiments are combined with temperature measurements along fiber optic cables installed in boreholes thermal dilution tests are shown to enable detection of cross flowing fractures and quantification of the cross flow rate a cross borehole thermal tracer test is then analyzed to identify fracture zones that are in hydraulic connection between boreholes and to estimate spatially distributed temperature breakthrough in each fracture zone this provides a significant improvement compared to classical tracer tests for which concentration data are usually integrated over the whole abstraction borehole however despite providing some complementary results we find that the main contributive fracture for heat transport is different to that for a solute tracer

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

using flowmeter pulse tests to define hydraulic connections in the subsurface a fractured shale example cross borehole flowmeter pulse tests define subsurface connections between discrete fractures using short stress periods to monitor the propagation of the pulse through the flow system this technique is an improvement over other cross borehole techniques because measurements can be made in open boreholes without packers or previous identification of water producing intervals the method is based on the concept of monitoring the propagation of pulses rather than steady flow through the fracture network in this method a hydraulic stress is applied to a borehole connected to a single permeable fracture and the distribution of flow induced by that stress monitored in adjacent boreholes the transient flow responses are compared to type curves computed for several different types of fracture connections the shape of the transient flow response indicates the type of fracture connection and the fit of the data to the type curve yields an estimate of its transmissivity and storage coefficient the flowmeter pulse test technique was applied in fractured shale at a volatile organic contaminant plume in watervliet new york flowmeter and other geophysical logs were used to identify permeable fractures in eight boreholes in and near the contaminant plume using single borehole flow measurements flowmeter cross hole pulse tests were used to identify connections between fractures detected in the boreholes the results indicated a permeable fracture network connecting many of the individual boreholes and demonstrated the presence of an ambient upward hydraulic head gradient throughout the site

development of in aquifer heat testing for high resolution subsurface thermal storage capability characterisation the ongoing transition from fossil fuels to alternative energy source provision has resulted in increased geothermal uses as well as storage of the shallow subsurface existing approaches for exploration of shallow subsurface geothermal energy storage often lack the ability to provide information concerning the spatial variability of thermal storage parameters however parameter distributions have to be known to ensure that sustainable geothermal use of the shallow subsurface can take place especially when it is subject to intensive usage in this paper we test a temperature decay time approach to obtain in situ direct qualitative spatial high resolution information about the distribution of thermal storage capabilities of the shallow subsurface to achieve this temperature data from a high resolution fibre optic distributed temperature sensing device as well as data from conventional pt100 temperature sensors were collected during a heat injection test the latter test was used to measure the decay time of temperature signal dissipation of the subsurface signal generation was provided by in aquifer heating with a temperature self regulating electric heating cable heating was carried out for 4 5 days after this a cooling period of 1 5 weeks was observed temperature dissipation data was also compared to direct push derived high resolution hydro geological data the results show that besides hydraulic properties also the bedding and compaction state of the sediment have an impact on the thermal storage capability of the saturated subsurface the temperature decay time approach is therefore a reliable method for obtaining information regarding the qualitative heat storage capability of heterogeneous aquifers for the use with closed loop system geothermal storage systems furthermore this approach is advantageous over other commonly used methods e g soil sampling and laboratory analysis as even small changes in hydro geological properties lead to strong variances in observed heat storage capabilities at the investigated case study site by using fibre optic thermometers nearly every requested spatial resolution can be achieved and easily be adjusted to the needs of actual test sites for shallow geothermal storage exploration