geochemistry of a spring dense karst watershed located in a complex structural setting appalachian great valley west virginia usa the distribution and chemistry of the springs in the tuscarora creek watershed is controlled by both geologic structure and karst dissolution the watershed is located in eastern west virginia in the structurally complex great valley of the appalachian valley and ridge province the upper portion of the stream parallels strike along a mapped fault zone and is bordered by clastic rocks that comprise north mountain the lower reaches of the stream flow cross strike through cambro ordovician carbonates the controlling chemical signature in the spring water is carbonate dissolution little evidence was seen for the recharge from adjacent clastic rocks although differences in the ca mg molar ratio between springs indicated the presence of localized spring basins in headwater reaches na cl and ca generally increased from upstream to downstream in the cross strike reaches comparison of stream and cumulative spring discharge was consistent with significant groundwater base flow contribution directly to the creek particularly in the strike parallel region the largest spring in the watershed 162 l s was sampled during and after a large storm event along with the adjacent creek the creek displayed a typical dilution response with each flood pulse whereas the spring had only a limited or delayed response the overall chemical and thermal stability of the spring relative to the creek indicated the lack of significant direct hydraulic connection between the two the conceptual model for the area includes localized flowpaths in the headwater region where the stream flow is parallel to strike and a thrust fault in addition to the shallow localized flowpaths a deeper more regional flowpath likely exists for a large spring further downstream

extreme detached dust layers near martian volcanoes evidence for dust transport by mesoscale circulations forced by high topography modeling suggests that thermal circulations over mars s highest volcanoes transport water vapor and dust from the surface into the middle atmosphere forming detached layers in these constituents intense vertical mixing also takes place in regional and global dust storms which can generate detached layers that are extreme in both altitude and magnitude here we employ observations by the mars climate sounder mcs on board mars reconnaissance orbiter taking advantage of improved vertical coverage in mcs s aerosol retrievals to discover a new class of extreme detached dust layers eddls observed during minimal dust storm activity and furthermore distinguished by their potentially large and measurable horizontal extent 1000 km these eddls cluster near olympus mons and the tharsis montes from which they likely originate the existence of these eddls suggests that vertical mixing by topographic circulations can be much stronger than previously modeled and more frequent than previously observed

monitoring mars with the hubble space telescope 1990 1991 observations images of mars obtained using the planetary camera on the hubble space telescope during 1990 and 1991 are described and analyzed multispectral images of mars record the martian season between ls 348 and 60 corresponding to late winter and spring in the northern hemisphere the wavelengths of these observations varied between 230 nm in the ultraviolet and 890 nm in the near infrared we use these images to discuss atmospheric and polar phenomena to constrain the aerosols and ozone in the martian atmosphere and to compare surface albedo features within this data set as well as with previous observations two methods are used to constrain the opacity of the martian atmosphere comparisons of ultraviolet images with atmospheric scattering models and examination of contrast changes of surface features observed at visible wavelengths our observations are consistent with a mars which was quite different from the planet when it was viewed by viking we estimate an upper limit of 0 1 for equatorial dust opacity near vernal equinox compared to values of 0 4 to 0 5 measured in chryse by viking lander 1 later at ls 60 an upper limit of 0 2 was found for dust in the southern hemisphere except for suggestions of local dust activity near the north polar cap in late spring there was no visual evidence of dust storms on the planet the hartley band of ozone is within the f230w filter bandpass and the 230w 336w ratio is therefore sensitive to ozone high latitude ozone is observed at a concentration similar to that observed by mariner 9 a seasonal dependence in ozone concentration was observed with concentration decreasing at northern arctic latitudes and increasing at southern midlatitudes as ls increases from 350 to 60 despite the difference in dust loading the behavior of condensate clouds and the recession of the north polar cap are consistent with those observed during viking years late winter images of the north polar region reveal an active north polar hood with a maximum uv opacity of about 0 25 near 50 latitude the hood seems to have an annular form with the central polar regions having smaller opacity clouds observed in the northern hemisphere to the south of the hood boundary are suggestive of fronts similar to those observed during the mariner 9 mission a diurnal variation in the hood clouds which is anti correlated with the amount of water vapor in the atmosphere is noted spring images show significant clouds in the tharsis elysium and arabia regions the most optically thick components of these clouds are those near elysium alba patera and tithonius in the afternoon although these regions also are bright on the morning limb the cloud associated with elysium had the largest optical depth for a cloud in the uv 0 4 most of the hst monitoring sequences were targeted on the syrtis major region an area which was intensively studied during the viking mission during viking there were major changes in the region which were attributed to the two major 1977 global dust storms on mars our series of images was projected onto map grids and photometrically corrected in order to study changes in the syrtis albedo features to first order syrtis does not change over the time period of these observations as would have been expected if they followed major global dust storms during the preceding season images were deconvolved using the richardson lucy iterative algorithm to remove the defocussing effects of the spherical aberration of the hst primary even when mars subtended less than 5 arcsec in may 1991 the images were scientifically useful and comparable to photographic images obtained at opposition although the data are subject to the solar pointing constraint for hst the relatively slow movement of the allowed observation window which is more than one half martian year with respect to the martian seasons will permit us to address the question of major variations in the martian atmosphere

preconditioning an ensemble kalman filter for groundwater flow using environmental tracer observations abstract groundwater resources management requires operational regional scale groundwater models accounting for dominant spatial variability of aquifer properties and spatiotemporal variability of groundwater recharge we test the ensemble kalman filter enkf to estimate transient hydraulic heads and groundwater recharge as well as the hydraulic conductivity and specific yield distributions of a virtual phreatic aquifer to speed up computation time we use a coarsened spatial grid in the filter simulations and reconstruct head measurements at observation points by a local model in the vicinity of the piezometer as part of the observation operator we show that the enkf can adequately estimate both the mean and spatial patterns of hydraulic conductivity when assimilating daily values of hydraulic heads from a highly variable initial sample the filter can also estimate temporally variable recharge to a satisfactory level as long as the ensemble size is large enough constraining the parameters on concentrations of groundwater age tracers here tritium and transient hydraulic head observations cannot reasonably be done by the enkf because the concentrations depend on the recharge history over longer times while the head observations have much shorter temporal support we thus use a different method the kalman ensemble generator keg to precondition the initial ensemble of the enkf on the groundwater age tracer data and time averaged hydraulic head values the preconditioned initial ensemble exhibits a smaller spread as well as improved means and spatial patterns the preconditioning improves the enkf particularly for smaller ensemble sizes allowing operational data assimilation with reduced computational effort in a validation scenario of delineating groundwater protection zones the preconditioned filter performs clearly better than the filter using the original initial ensemble

an examination of the formation of linear lee waves generated by giant martian volcanoes abstract the vertical wave displacement generated by a martian volcano at heights comparable with and above the altitude of the topography is investigated in this paper an examination is made of the leakage of this displacement into atmospheric heights well above the topography and consideration is given to two large martian volcanoes olympus mons and ascraeus mons viking orbiter imagery portraying wave clouds in the vicinity of these volcanoes is compared with theoretical results obtained by considering a simple one layer atmosphere in which the ratio of the stability factor to the square of the atmospheric velocity profile is deemed to be constant at all vertical levels it is found that a wave plume phenomenon is predicted by this theory and by comparing with visual observations information can be deduced as to the atmospheric mean structure of velocity and stability when these cloud formations occur

hubble space telescope observations of the martian aphelion cloud belt prior to the pathfinder mission seasonal and interannual variations the presence of a globally extant equatorial belt of water ice clouds on mars is quantitatively investigated using data from three seasons of our hubble space telescope synoptic monitoring program 1993 1997 a subset of the 1996 1997 images covers the landing site of the mars pathfinder including a set of images taken after touchdown using multicolor imaging from the wide field planetary camera and the wide field planetary camera 2 we characterize both water ice cloud and dust optical depths as a function of latitude at several local times for each observing epoch the analysis technique models calibrated data using a multiple scattering radiative transfer code our results support the initial results of clancy et al 1996a regarding changes between the aphelion and perihelion climate of mars and provide a more detailed look at the development and decay of the cloud belt comparing our dust optical depths to those of the viking landers for the same seasons we note a trend toward lower dust loading in late northern winter and in spring our observations of the pathfinder site in july 1997 reveal a dust opacity in good agreement with that reported by pathfinder smith et al 1997b in addition the serendipitous occurrence of a dust storm in valles marineris in late june 1997 allows us to derive a set of dust single scattering albedos for use in more accurately modeling the dust s radiative properties and effects

spectral imaging of martian water ice clouds and their diurnal behavior during the 1999 aphelion season ls 130 abstract we report high spectral resolution 800 2300 near infrared mapping observations of mars at ls 130 april 1999 which were obtained by drift scanning the cryogenic long slit spectrometer at the kpno 2 2 m telescope across the disk data were reformatted into calibrated spectral image cubes x y spanning 2 19 to 4 12 m which distinguish atmospheric co2 features solar lines and surface and aerosol features maps of relative band depth between 3 0 and 3 5 m trace water ice clouds and show the diurnal evolution of features in the persistent northern summer aphelion cloud belt which was mapped contemporaneously but at fixed local time by the mars global surveyor thermal emission spectrometer mgs tes cloud optical depth particle sizes and ice aerosol content were estimated using a two stream single layer scattering model with mie coefficients derived from recently published ice optical constants followed by a linear spectral deconvolution process a comparison of data and model spectra shows evaporating nighttime clouds in the morning followed by afternoon growth of a prominent orographic cloud feature on the west flank of elysium mons cloud optical depth at 3 2 m evolved to 0 28 0 13 and ice aerosol column abundance to 0 9 0 3 pr m in the afternoon column abundances as large as 0 17 pr m were retrieved in nonorographic clouds within the aphelion cloud band around midday these clouds exhibit a modest decline in optical depth during the afternoon results show that ice particle radii from 4 m exist in both cloud types however large particles dominate the spectra consistent with recent mgs tes emission phase function measurements of aphelion cloud aerosol properties

mars aerosol studies with the mgs tes emission phase function observations optical depths particle sizes and ice cloud types versus latitude and solar longitude 1 emission phase function epf observations taken in 1999 2001 by mars global surveyor thermal emission spectrometer mgs tes support the broadest study of martian aerosol properties to date tes solar band and infrared ir spectral epf sequences are analyzed to obtain first time seasonal latitudinal distributions of visible optical depths particle sizes and single scattering phase functions this combined angular and wavelength coverage enables identification of two distinct ice cloud types over 45 s 45 n type 1 ice clouds exhibit small particle sizes reff 1 2 m and a distinctive backscattering increase they are most prevalent in the southern hemisphere during aphelion but also appear more widely distributed in season and latitude as topographic and high altitude 20 km ice hazes type 2 ice clouds exhibit larger particle sizes reff 3 4 m a distinct side scattering minimum at 90 100 phase angles characteristic of a change in particle shape relative to the type 1 and appear most prominently in the northern subtropical aphelion cloud belt the majority of retrieved dust visible to ir optical depth ratios are indicative of reff 1 5 0 1 m consistent with pathfinder and viking mariner 9 reanalyses however increased ratios 2 7 versus 1 7 appear frequently in the northern hemisphere over ls 50 200 indicating substantially smaller dust particles sizes reff 1 0 0 2 m at this time in addition larger reff 1 8 2 5 m dust particles were observed locally in the southern hemisphere during the peak of the 2001 global dust storm detailed spectral modeling of the tes visible band pass indicates agreement of epf derived dust single scattering albedos 0 92 0 94 with the spectrally resolved results from pathfinder observations

sublimation and transport of water from the north residual polar cap on mars several features of the viking mars atmospheric water detection observations have suggested that the residual north polar cap on mars is a major source of atmospheric water during northern summer and that the water it supplies to the atmosphere is transported equatorward to low northern latitudes by summer s end we have explored the role of the north residual cap in the current martian water cycle by constructing models to assess the ability of the cap to supply water to the atmosphere and the ability of the atmosphere to transport it out of the polar regions from our sublimation model we conclude that the residual cap can sublime the 7 1014 g of water that appears in the atmosphere after ls 80 provided surface winds are high 10 m s the cap emissivity is low 0 9 or the exposed soil in polar regions contains ice that is accessible to the atmosphere in our view these requirements seem unlikely and we are drawn to the conclusion that other sources of water exist this conclusion is further supported by the results of two dimensional transport simulations which show that most of the water sublimed from the cap remains at high latitudes the polar circulation simply lacks the intensity and scale to move water very far from the cap a weak circulation places additional constraints on cap sublimation rates since abundant clouds and significant ice deposits would form just equatorward of the cap edge according to the model if the cap is allowed to sublime 7 1014 g of water such predictions are inconsistent with available data we suggest that the nature of the additional source is water desorbing from the nonpolar regolith

some observational constraints on the global scale wind systems of mars wind direction measurements from a variety of indicators taken over several mars years and covering the entire planet have been collected these include observations of lee wave clouds not previously studied the data exhibit a high degree of consistency and seasonal reproducibility making it possible to interpret most of the observations in terms of the zonally symmetric circulation of mars we examine these data in the context of the constraints the observed wind directions place upon the thermal and polar cap mass flux fields which force the flows within the limitations of the data set mid and high latitude winds appear to be controlled by the thermal field during mid and late summer and winter and in the northern hemisphere during early spring and early summer at other times the cap flows dominate at high latitudes the strongest yearly winds are probably generated by cap formation in the north and cap recession in the south the hemispheric asymmetry seems to result primarily from the effects of global dust storms on the north polar cap turning of the prograde wind from poleward to equatorward in midautumn is observed consistent with reduced poleward mass flux and increased meridional temperature gradient at that time the latitudinal extent of the equatorial hadley cell when observed is probably larger than that predicted by nearly inviscid models of low latitude circulation the cross equational hadley cell and high latitude poleward flows which occur in both hemispheres during the summer seasons may set additional constraints on the thermal forcing mechanisms at these times

mars south polar hood as observed by the mars climate sounder 1 we have used observations from the mars climate sounder to investigate south polar hood water ice clouds at 12 m including the first systematic examination of the vertical 5 km resolution and nighttime structure we find that the structure and evolution of the polar hood is controlled more strongly by atmospheric temperature variations than by intrinsic fluctuations in water vapor abundance the clouds form as a belt during ls 10 70 phase 1 and ls 100 200 phase 2 during phase 1 the cloud belt extends over a wide latitude range between 30 s and 75 s with a visible column optical depth between 0 075 and 0 15 the cloud belt then evaporates as temperatures warm during phase 2 the cloud belt reappears due to an increase in water vapor as a partial band of low opacity clouds south of the tharsis region and eventually becomes continuous in longitude with a visible column opacity between 0 125 and 0 25 as the southern spring equinox approaches the cloud belt shifts southward following the seasonal cap edge from ls 140 to ls 200 the daytime belt lies about 15 farther south than the nighttime belt due to tidally driven diurnal temperature differences the vertical structure of the cloud belt is consistent within and between the two seasonal phases and is characterized by a thick lower cloud deck and an upper layer whose altitude shifts between the nighttime and daytime because of thermal tidal control of the condensation altitudes overall the southern polar hood is observed to rapidly form and dissipate as the temperature crosses the saturation point of water vapor

variations in martian surface composition and cloud occurrence determined from thermal infrared spectroscopy analysis of viking and mariner 9 data viking infrared thermal mapper irtm and mariner 9 infrared interferometer spectrometer iris data were examined for evidence of spatial variations in the composition of surface materials and the abundance of atmospheric condensates the irtm instrument collected broadband spectral radiance in bands centered at 7 9 11 and 20 m these measurements were converted to emissivities at 9 11 and 20 m and used to construct multispectral images at five seasons ls 90 180 180 360 0 90 90 180 and 180 360 and at local times of 6 8 8 10 10 12 12 14 and 14 16 h 24 h equals one martian day during dusty periods ls 180 360 these images clearly revealed the presence of suspended dust during clear periods ls 0 180 the seasonal and diurnal variations in water ice cloud occurrence could be mapped using the 11 m irtm band clouds tended to occur over the tharsis region and the region between 0 and 60 w near the equator and to evolve from dispersed hazes to more localized hazes during the day as northern summer progressed during the viking period the northern clouds transitioned from a diffuse haze to a more concentrated zone of clouds in the equatorial region with a well defined northern boundary during clear periods the irtm multispectral data reveal significant absorptions at 9 11 and 20 m that are strongly correlated with surface albedo these absorptions are produced by surface materials and individual four point spectra show compositional variations within both dark and bright material types the iris instrument collected high spectral resolution 2 4 cm 1 data from 6 to 50 m unfortunately only 85 daytime spectra out of the 21 000 total collected were acquired after the intense global dust storm of 1971 subsided after ls 330 the close agreement of these spectra convolved to irtm resolution with the irtm surface spectra confirms that they also represent surface rather than atmospheric materials the irtm four point spectra show similarities with plagioclase feldspar minerals clays and pyroxenes although the low spectral resolution of irtm prevents definitive mineral identification carbonates do not compose a significant fraction of the dark region materials the iris surface spectra show similarities with feldspars clays and pyroxenes in the 8 12 m region but do not match any of these minerals well in the 18 25 m region overall the irtm and iris data are consistent with previous suggestions of mafic to ultramafic compositions but data provide stronger evidence that unweathered plagioclase feldspars may be significant components of the present surface together the irtm and iris reveal the presence of absorption features associated with surface materials which should permit detailed surface compositional mapping using future thermal ir spectral measurements

mars south polar spring and summer behavior observed by tes seasonal cap evolution controlled by frost grain size thermal emission spectrometer tes observations of the recession phase of mars south polar cap are used to quantitatively map this recession in both thermal and visual appearance geographically nonuniform behavior interior to the cap is characterized by defining several small regions which exemplify the range of behavior for most of the cap while temperatures remain near the co2 frost point albedos slowly increase with the seasonal rise of the sun then drop rapidly as frost patches disappear over a period of 20 days a cryptic region remains dark and mottled throughout its cold period tes observations are compared with first order theoretical spectra of solid co2 frost with admixtures of dust and h2o the tes spectra indicate that the cryptic region has much larger grained solid co2 than the rest of the cap and that the solid co2 here may be in the form of a slab the mountains of mitchel remain cold and bright well after other areas at comparable latitude apparently as a result of unusually small size of the co2 frost grains we found little evidence for a significant presence of h2o although co2 grain size may be the major difference between these regions incorporated dust is also required to match the observations a self cleaning process carries away the smaller dust grains comparisons with viking observations indicate little difference in the seasonal cycle 12 martian years later the observed radiation balance indicates co2 sublimation budgets of up to 1250 kg m 2 regional atmospheric dust is common localized dust clouds are seen near the edge of the cap prior to the onset of a regional dust storm and interior to the cap during the storm

inter comparison exercises on dissolved gases for groundwater dating 1 goals of the exercise and site choice validation of the sampling strategy abstract two international inter comparison exercises devoted to dissolved gases and isotope analyses in groundwater used as tools for groundwater dating were organized in 2012 in france ides universite paris sud cnrs and osur universite rennes 1 cnrs the goal was to compare sampling and analytical protocols through results obtained by the community of groundwater dating laboratories the two exercises were gdat1 on three supply boreholes in a homogeneous sand aquifer of fontainebleau paris basin france and gdat2 on two supply boreholes shallow and deep in a fractured rock aquifer in french brittany this two step exercise is the first exercise which included a large number of gases and isotopes usually used in groundwater as dating tools and also permit to discuss the uncertainties related to sampling protocols issuing from each laboratory methods the two tests allowed 31 laboratories from 14 countries to compare their protocols for both sampling and analyses this paper presents the participants and parameters measured and focuses on the validation of the sampling strategy two laboratories analyzed cfc and sf6 samples collected at regular intervals during the sampling operations in order to verify water homogeneity the results obtained by the two reference laboratories along with monitoring of field parameters showed no clear trend of gas concentration or physic chemical properties it can be concluded that the pumped groundwater composition remained constant during sampling this study also shows the potential for relatively constant pumped groundwater composition from a specific well despite the complexity and or mixing processes that may occur at a larger scale in the aquifer

origin and evolution of a cold based tropical mountain glacier on mars the pavonis mons fan shaped deposit 1 each of the large tharsis montes volcanoes in the equatorial region of mars has an unusual amazonian aged fan shaped deposit on its west northwestern flank on the basis of viking orbiter data the origin of these deposits has been variously ascribed to volcanic mass wasting tectonic and glacial processes using new mgs and odyssey data combined with recent developments in the study of cold based glaciers we reassess the geology and mode of origin for these deposits with particular emphasis on pavonis mons the deposits share three characteristic facies including 1 a ridged facies consisting of tens to 100 parallel concentric ridges around the margins of the deposits 2 a knobby facies composed of irregular hills and hummocks and 3 a smooth facies of broad lobate plains that superposes all other units within the deposits on the basis of morphology topography superposition relationships and close terrestrial analogs in the dry valleys of antarctica we interpret the pavonis fan shaped deposit as the depositional remains of a cold based glacier that formed on the northwestern flank in recent martian history we interpret the ridged facies as drop moraines formed around the margins of a retreating cold based glacier the knobby facies as a sublimation till derived from in situ down wasting of cold based glacial ice and the smooth facies as extant debris covered glacial ice in addition to the three main facies the fan shaped deposit at pavonis mons contains several unique features including arcuate scarps high relief flow like features and radial ridges which suggest that volcanism played a role during its formation using recent results from mars general circulation model simulations we outline a model of glacier formation involving atmospheric deposition of water ice on the northwestern flanks of the tharsis montes during periods of high mean obliquity reconstructed ice sheet profiles for each of the tharsis montes glaciers suggest that the ice sheets attained average thicknesses of 1 6 2 4 km values that are consistent with a cold based glacial origin analysis of crater size frequency distributions using new data indicates that the age of the glaciation lies within the late amazonian 10 200 ma thus our results suggest that multiple phases of tropical mountain glaciation occurred on mars within the past few hundred myr and that significant amounts of near surface equatorial ice may remain within the deposit today

crustal structure and composition of the oslo graben norway abstract although more than 250 my old the oslo graben has retained a distinctive distribution of p wave velocities associated with rifting intrusion and underplating of the thinned crustal section we calculate poisson s ratio values from crustal p and s wave velocities along an 400 km long profile across the southern scandinavian peninsula with a focus on the oslo graben plutonic rocks are now exposed at the surface in the graben due to post rifting erosion and the corresponding low 5 5 km s p wave velocities extend to depths of 3 km the p wave velocity and poisson s ratio between depths of 6 and 34 km are 5 higher inside than outside the rift boundaries which together with thickening of the 7 km s lower crust beneath the rift indicate magmatic intrusions poisson s ratio of 0 27 and high 7 1 7 4 km s velocities indicate a heterogeneous composition lower crust the thickened high velocity lower crust is 1 5 times wider than the surface expression of the rift and extends to both the east and west of the main rift axis depth dependant extension may have occurred within the rift and may account for the significant volumes of volcanic output despite the small surface extension observed the added volume of intrusive material may explain why the moho up warp is small as little as 2 km at the rift based on the new p wave velocities poisson s ratio measurements and the thickness of the magmatic underplate apparent values for the rift are estimated to be 1 5 but when intrusion within the crust is included could be as high at 2 3

infrared spectral imaging of martian clouds and ices abstract multispectral images of mars taken at the nasa infrared telescope facility irtf near and at the 1995 opposition are used to identify and track its atmospheric clouds and ground ices band depth mapping is used to help distinguish between the composition of volatiles and provide a check for the techniques of principal components analysis pca and linear mixture modeling lmm pca lmm are used to create maps that track clouds and volatiles a technique that requires no a priori spectral information in order to create these maps band depth maps at 3 33 m which have been shown to trace co 2 frosts show some transient features which could indicate polar co 2 clouds at the time of these observations we show that band depth maps at 2 25 m are good tracers of h 2 o frosts and that band depth maps at 3 69 m can distinguish between coarse and fine grained water frosts these maps have allowed the detection of fine grained water frosts in the north polar region and along the morning and evening limb regions from the pca technique we find that just two principal components can account for over 99 of the data variance the first of these is an infrared albedo unit and the second is an ice thermal unit plotting the spectral data cubes in this new vector space we find that most of the martian disk can be modeled by spectrally mixing three endmember spectra having extreme values of these principal components the morning and evening regions of mars are composed of 40 60 of the north polar ice thermal component endmember indicating a frost component there consistent with the band depth mapping results with a combination of these techniques it is possible to not only identify the extensive martian clouds but to also determine composition these new results are particularly relevant in light of recent mars pathfinder descent temperature profile data that indicated upper atmosphere temperatures below the co 2 frost condensation point implying that co 2 ice clouds may be an important radiative component of the current martian climate

the spatial and seasonal distribution of martian clouds and some meteorological implications the spatial and seasonal distributions of martian atmospheric clouds organized according to simple morphologic criteria exhibit distinct patterns when interpreted self consistently using analogies to terrestrial cloud forms and martian temperature wind direction and water vapor measurements patterns of cloud occurrence provide some loose constraints on global scale near surface wind speed static stability and humidity we have examined all mariner 9 and viking orbiter images for this study we concentrate primarily on the larger viking data set whenever observations are possible relatively high near surface winds appear to follow the seasonal cap edges during early fall late winter and spring moderate to high winds are also inferred in mid latitudes for mid southern winter and in low latitudes mainly in the steeply sloping areas of tharsis near the solstices at other times lower winds are suspected hemispheric asymmetries are traced to differences in atmospheric hydration state and to global dust storm related effects on the atmospheric temperature structure and the north polar cap recession schedule cloud occurrence data suggest that the near surface daytime static stability is low in the northern hemisphere during summer and at low latitudes during mid northern spring relatively high static stability is deduced near the winter poles and globally during the dust storm season in spite of low atmospheric temperatures the correspondingly low absolute humidity apparently precludes the formation of thick water ice clouds at high latitudes in mid to late autumn and winter in both hemispheres and in southern mid latitudes during early winter during northern spring and summer saturation conditions seem to be easily achieved at mid latitudes and condensate clouds are abundant the situation is complicated by atmospheric dust in southern spring and summer low latitudes generally appear to be farther from saturation than mid latitudes and clouds generally form more easily in the northern hemisphere than in the south during corresponding seasons

natural cf4 and sf6 on earth the occurrence of cf4 and sf6 in natural fluorites caf2 is reported contents are found to be typically 200 2000 ppt mass for cf4 and 50 100 ppt mass for sf6 cf4 and sf6 were also detected in granites where fluorite is an accessory mineral cf4 and sf6 thus possess a large reservoir in the continental crust that by degassing can sustain natural atmospheric background levels of 40 ppt mole and up to 0 01 ppt mole respectively the article also discusses how natural sf6 may cause interference in hydrological tracer studies

seismic structure and composition of the crust beneath the southern scandes norway abstract new results on p and s wave seismic velocity structure in southern norway indicate that the crust has an average poisson s ratio of 0 25 is predominantly of felsic intermediate composition and lacks a significant mafic lower crust a crustal scale refraction seismic study magnus rex mantle investigations of norwegian uplift structure refraction experiment acquired data along three 300 to 400 km long active source seismic profiles across the southwest scandinavian domain in southern norway the youngest section of the fennoscandian shield moho depths in the domain are 36 40 km thinning towards the continental shelf and oslo graben the high vp lower crust beneath the southwest scandinavian domain vp 7 km s is around 4 km thick crustal structure in the adjacent svecofennian domain differs significantly moho depths reach 50 km and an up to 24 km thick high vp lower crust is present strong p and s wave arrivals are recorded from magnus rex from which poisson s ratio for the crust is calculated the unusually strong s wave arrivals allow rare insight into crustal poisson s ratio structure that is not commonly available from active source data the thinness of the mafic lower crust in southern norway is in significant contrast to other parts of the fennoscandian shield and delamination or convective removal of the lower crust is proposed tectonic events that may have triggered detachment of the lower crust include extensional collapse after the caledonian orogeny and permian extension

global imaging of mars by hubble space telescope during the 1995 opposition hubble space telescope hst imaging of mars near the 1995 opposition resulted in excellent synoptic scale images of the planet during the spring season in the northern hemisphere because this season coincides with the aphelion position of mars in its orbit it is therefore the most difficult for ground based observation because of the relatively small angular size of mars this is the first sequence of images fully utilizing the capability of the new planetary camera to produce global synoptic images of the planet the images reveal bright discrete clouds associated with topographic features superimposed on a zonal band of condensate clouds between latitudes 10 and 30 the maximum violet optical depth of the cloud band is about 0 3 in a few instances the appearance of clouds beyond the morning terminator can be used to infer cloud heights of roughly 8 km a large dark albedo feature in the cerberus region observed for many years by ground based observers has almost disappeared in the 1995 hst images other aspects of mars such as the north polar cap appear much as they did during previous oppositions although cloudy regions were observed by spacecraft during this season the hst images uniquely reveal the global extent of significant optical depth clouds

water ice nucleation characteristics of jsc mars 1 regolith simulant under simulated martian atmospheric conditions 1 water ice clouds in the martian atmosphere are governed by parameters such as number density and particle size distribution that in turn affect how they influence the climate with some of the underlying properties of cloud formation well known only for earth extrapolations to mars are potentially misleading we report here continued laboratory experiments to identify critical onset conditions for water ice formation under martian cloud forming temperatures and water partial pressures 155 182 k 7 6 10 5 to 7 7 10 3 pa h2o by observing the 3 m infrared band to monitor nucleation and growth we observe significant temperature dependence in the nucleation of ice on jsc mars 1 regolith simulant with critical saturation ratios scrit as high as 3 8 at 155 k at temperatures below 180 k ice nucleation on jsc mars 1 requires significant supersaturation potentially impacting the martian hydrological cycle

mars w cloud evidence of nighttime ice depositions 1 water clouds on mars their current and past connections with other forms of water along with surface features that suggest the early existence of flowing water continue to be intriguing aspects of the red planet discrete afternoon mountain clouds were one of the earliest atmospheric features to be observed on mars their exclusive formation near the high mountains led to the common belief that air lifting associated with local circulation induced by the mountains underlies their formation we demonstrate that an additional local source of water vapor is needed for the formation of opaque discrete afternoon clouds on the mountains of mars including the so called w formation we suggest that the possible deposition of ice from the thick aphelion cloud belt during the night is capable of providing this additional source this direct cloud water deposition on mountains on mars bears many similarities with the well known interception of water by mountains frequently immersed in fogs on earth

cloud formation under mars pathfinder conditions temperature data taken during the mars pathfinder entry are applied to a time dependent microphysical model of cloud formation our goal is to reproduce the characteristics of clouds observed at the pathfinder site we assume that the total water column abundance is 11 percipitable microns we also assume that the atmospheric dust initially has a lognormal size distribution with a modal radius of 0 6 m r eff 1 5 m and an optical depth of 0 5 three temperature profiles are used in the model calculations the first is the pathfinder entry observation the second is this same profile but with the inversion at 10 km removed the third simulation uses the temperature profiles calculated by the ames mars general circulation model for mars pathfinder conditions in all cases clouds form at altitudes of 35 45 km in addition lower thicker clouds form within the 10 km inversion of the unaltered profile while peak cloud formation occurred near local noon at 20 km for the gcm calculated profiles given a combination of all three temperature scenarios cloud optical depths particle sizes and colors are consistent with imp observations

long cloud observations on mars and implications for boundary layer characteristics over slopes viking orbiter images of mars show several instances of long continuous cloud formations on the slopes of arsia and pavonis mons we have searched all the images of the planet for occurrences of such formations only in the tharsis region were long clouds unambiguously identified we have measured the times and locations of occurrence the wavelengths and when possible the apparent velocity of motion of these clouds we have also tabulated the wavelengths of patches of ripple clouds that are often found with the long formations the long clouds are observed only in the early morning hours suggesting that they are associated with drainage winds due to a cold planetary boundary layer we develop simple mathematical models to examine various aspects of such boundary layer winds these allow us to construct a complete and self consistent explanation of all the observed features of the cloud formations we use the results to characterize some physical properties of the mars boundary layer there is strong downslope flow in the boundary layer on the high slopes of both volcanos in the saddle region between the peaks the flow slows and undergoes a hydraulic jump producing the long clouds downstream of the jump standing internal gravity waves can exist and are excited by flow over surface irregularities small variations in their observed wavelengths behind the jump may be attributed to variation in the flow speed and depth finally we can account for the location of the jumps by the variation of relative strength of the boundary layer flows on the two volcanos

dissolved gases in groundwater and groundwater dating methods how useful for hydrogeological modeling foreword to the special issue one of the major challenges in hydrogeology is the basic spatial lack of continuous data as this is restricted to available boreholes basic information is provided by the measurements of physical parameters e g porosity and permeability at the well scale information related to a larger part of the aquifer are provided for example by continuous measurement of piezometric levels or spring flow temporal information is extremely powerful in order to characterize aquifer functioning globally groundwater dating has thus been developed in order to provide time constraints in aquifer studies

numerical simulations of the formation and evolution of water ice clouds in the martian atmosphere abstract a one dimensional aerosol model was used to study the microphysics of water ice cloud formation and evolution on mars the time dependent nature of the model permits realistic simulations of diurnal cycles the results are sensitive to the choice of the temperature profile the eddy diffusion coefficient the efficiency of nucleation of the condensation nuclei and the condensation history of the cloud simulations having a large diurnal temperature variation yield condensed water total optical depths of a few tenths in good agreement with the viking lander opacity data ice clouds are typically simulated at 25 30 km altitude with mean particle radii of 0 2 5 0 m we also obtain good agreement with the particle extinction observed in the viking orbiter limb data for a temperature profile constrained by the infrared thermal mapper data in order for repeated cloud formation to occur each day we need to include a vertical and or horizontal resupply of water and dust to the higher altitudes where the condensation occurs because of loss by sedimentation this can take the form of a micrometeoritic influx of particles at the top of the atmosphere or a latitudinal transport of material the efficiency of the nucleation process is determined by the contact angle changing this angle from 0 945 to 0 999 can have the effect of doubling the total ice optical depth of the cloud the time evolution of the cloud is important for comparison with the observations if a diurnal temperature change exists under these conditions the optical thickness of the cloud is dependent on the number of condensation cycles having previously occurred and the time of day this time dependence and the need for a resupply of material into the condensing region show that the cloud formation process cannot be considered a steady state phenomenon we have shown that the eddy diffusion coefficient and particle radii cannot be constrained by the available data even if a detailed model is used for the interpretation of the observations in our simulations there is an extensive vertical redistribution of water by clouds however water is only lost to the surface when the temperature is at the frost point near the ground precipitation across subsaturated layers is not significant

titaniferous magnetite ilmenite thermometry and titaniferous magnetite ilmenite orthopyroxene quartz oxygen barometry in granulite facies gneisses bamble sector se norway implications for the role of high grade co 2 rich fluids during granulite genesis oxygen fugacities have been estimated for a wide distribution of samples from the granulite facies terrane region c of the bamble sector se norway using both the titaniferous magnetite ilmenite and orthopyroxene titaniferous magnetite quartz oxygen barometers these oxygen fugacities are estimated using temperatures calculated from the titaniferous magnetite ilmenite thermometer of ghiorso and sack 1991 and are both internally consistent with each other as well with the thermometer in samples for which the estimated temperature is high the two oxygen barometers show good agreement whereas agreement is poor for low temperature samples in these low temperature samples oxygen fugacities estimated from titaniferous magnetite ilmenite are considerably less than those estimated from orthopyroxene titaniferous magnetite quartz an increase in this discrepancy with decrease in temperature appears to reflect preferential resetting of the hematite component in the ilmenite grains without significant alteration of the more numerous titaniferous magnetite grains this is due in part to greater re equilibration of the ilmenite grains during retrograde interoxide resetting between the ilmenite grains and the titaniferous magnetite grains the mean temperature for the non reset samples 791 17 c 1 is in good agreement with temperatures obtained from garnet orthopyroxene kd exchange thermometry in the same region 785 795 c 1 harlov 1992 2000a most non reset oxygen fugacities range from log10 f o2 14 to 11 8 or approximately 0 5 1 5 log units above quartz fayalite magnetite at 7 5 kbar both these temperatures and the range of oxygen fugacities are in good agreement with those estimated using the titaniferous magnetite ilmenite thermometer oxygen barometer of andersen et al 1991 the quilp equilibrium quartz ulvospinel ilmenite pyroxene is used to project self consistent equilibrium temperatures and oxygen fugacities for samples reset due to hematite loss from the ilmenite grains these projected temperatures and oxygen fugacities agree reasonably well with the non reset samples the mean projected quilp temperature is 823 6 c 1 this result supports the conclusion that low titaniferous magnetite ilmenite temperatures down to 489 c and accompanying low oxygen fugacities are the result of hematite loss from the ilmenite grains non reset oxygen fugacities lie approximately 1 5 log10 units above the upper graphite stability curve indicating that the stable c o h fluid phase interacting with these gneisses whether regionally or locally was co2 this is borne out by the presence of numerous co2 rich fluid inclusions in these rocks

dating groundwater with trifluoromethyl sulfurpentafluoride sf5cf3 sulfur hexafluoride sf6 cf3cl cfc 13 and cf2cl2 cfc 12 1 a new groundwater dating procedure using the transient atmospheric signal of the environmental tracers sf5cf3 cfc 13 sf6 and cfc 12 was developed the analytical procedure determines concentrations of the four tracers in air and water samples sf5cf3 and cfc 13 can be used to date groundwaters in some environments where the cfcs and sf6 have previously failed because these new tracers have increasing atmospheric input functions no known terrigenic source and are believed to be stable under reducing conditions sf5cf3 has a dating range from 1970 to modern the mixing ratio mole fraction in north american air has increased from the detection limit of 0 005 parts per trillion ppt to the 2006 mole fraction of about 0 16 ppt no evidence was found for degradation of sf5cf3 in laboratory anaerobic systems the solubility of sf5cf3 was measured in water from 1 to 35 c groundwater samples that contained large amounts of terrigenic sf6 did not contain terrigenic sf5cf3 cfc 13 is a trace atmospheric gas with a dating range in groundwater of about 1965 to modern cfc 13 has been used primarily in very low temperature refrigeration thus groundwater environments are less likely to be contaminated with nonatmospheric sources as compared to other widely used cfcs because of the low solubility of sf5cf3 and cfc 13 in water an excess air correction must be applied to the apparent ages the new dating procedure was tested in water samples from wells and springs from maryland virginia and west virginia

curvilinear features in the southern hemisphere observed by mars global surveyor mars orbiter camera abstract we have used the complete set of mars global surveyor mgs mars daily global maps mdgms to study martian weather in the southern hemisphere focusing on curvilinear features including frontal events and streaks frontal events refer to visible events that are morphologically analogous to terrestrial baroclinic storms mdgms show that visible frontal events were mainly concentrated in the 210 300 e 60 150 w sector and the 0 60 e sector around the southern polar cap during l s 140 250 and l s 340 60 the non uniform spatial and temporal distributions of activity were also shown by mgs thermal emission spectrometer transient temperature variations near the surface streaks refer to long curvilinear features in the polar hood or over the polar cap they are an indicator of the shape of the polar vortex streaks in late winter usually show wavy segments between the 180 meridian and argyre model results suggest that the zonal wave number m 3 eastward traveling waves are important for their formation

interannual variability of water ice clouds over major martian volcanoes observed by moc abstract using mars global surveyor mars orbiter camera daily global maps cloud areas have been measured daily for water ice clouds associated with the topography of the major volcanoes olympus mons ascraeus mons pavonis mons arsia mons elysium mons and alba patera this study expands on that of benson et al benson j l bonev b p james p b shan k j cantor b a caplinger m a 2003 icarus 165 34 52 by continuing their cloud area measurements of the tharsis volcanoes olympus mons and alba patera for an additional martian year august 2001 may 2003 and by also including elysium mons measurements from march 1999 through may 2003 the seasonal trends in cloud activity established by benson et al benson j l bonev b p james p b shan k j cantor b a caplinger m a 2003 icarus 165 34 52 for the five volcanoes studied earlier are corroborated here with an additional year of coverage for volcanoes other than arsia mons interannual variations that could be associated with the large 2001 planet encircling dust storm are minimal at arsia mons where cloud activity was continuous in the first two years clouds disappeared totally for 85 of l s l s 188 275 due to the dust storm elysium mons cloud activity is similar to that of olympus mons however the peak in cloud area is near l s 130 rather than near l s 100

martian north polar hazes and surface ice results from the viking survey completion mission viking infrared observations of the martian north polar regions taken during the 1979 1980 viking survey completion mission have been used to determine the location and nature of the retreating polar cap edge and of an accompanying atmospheric ice haze the haze is composed of water ice and its visible opacity is approximately unity equivalent to 1 2 precipitable microns of water ice during the polar cap retreat aerocentric longitude ls 340 60 the haze is nearly always present and extends from at most a few degrees south of the polar cap edge to an undetermined distance over the cap interior the transition from ice free ground to a predominantly ice covered surface at the cap edge spans 5 10 of latitude the ability of the viking infrared observations to distinguish haze from surface condensate yields a more accurate seasonal regression for the polar cap than can be determined from visual images generally the infrared observations presented here yield a regression similar to those determined from earth based and or spacecraft visual data for the same and for previous northern springs however there are differences concerning details of the cap retreat the thermal data indicate that the martian seasonal polar cap did extend south of 60 n during this particular late winter and that the midspring resumption of the cap retreat occurs at ls 50

dusty deep convection in the mars year 34 planet encircling dust event dusty convection convective activity powered by radiative heating of dust is a ubiquitous phenomenon in mars s atmosphere but is especially deep that is impactful on the middle atmosphere and widespread during planet encircling dust events pede that occur every few mars years my yet the relative roles of dusty deep convection and global dynamics such as the principal meridional overturning cell pmoc and the radiative tides in dust storm development and the vertical transport of dust and water are still unclear here observations from the mars climate sounder on board mars reconnaissance orbiter mro mcs are used to study dusty deep convection and its impact on middle atmospheric water content during the my 34 pede commenced june 2018 additional context is provided by mro mcs observations of the my 28 pede commenced june 2007 this investigation establishes that a few localized centers of dusty deep convection in the tropics formed in the initial phases of both pede simultaneously with a substantial increase in middle atmospheric water content the growth phase of the my 34 pede was defined by episodic outbreaks of deep convection along the acidalia and utopia storm tracks as opposed to less episodic more longitudinally distributed convective activity during the my 28 pede the most intense convection during both pede was observed in southern eastern tharsis where mro mcs observed multiple instances of deep convective clouds transporting dust to altitudes of 70 90 km these results suggest that martian pede typically contain multiple convectively active mesoscale weather systems

marci and moc observations of the atmosphere and surface cap in the north polar region of mars abstract we used mgs moc and mro marci daily mapping images of the north polar region of mars from 16 august 2005 ls 270 to 21 may 2009 ls 270 covering portions of three consecutive martian years my 27 my 29 to observe the seasonal behavior of the polar ice cap and atmospheric phenomena the rate of cap regression was similar in my 28 and my 29 but was advanced by 3 5 of ls 7 8 sols in my 29 the spatial and temporal behaviors of dust and condensate clouds were similar in the two years and generally in accord with prior years dust storms 100 km2 were observed in all seasons with peak activity occurring at ls 10 20 from 50 n to 70 n and at ls 135 140 from 70 n to 90 n the most active quadrant was 0 90 w in my 28 shifting to 180 270 w in my 29 the majority of regional storms in both years developed in longitudes from 10 w to 60 w during late summer the larger storms obscure the north polar region in a cloud of dust that transitions to north polar hood condensate clouds around autumnal equinox changes in the distribution of perennial ice deposits especially in olympia planum were observed between the 2 years with the my 29 ice distribution being the most extensive observed to date modeling suggests that the small bright ice patches on the residual cap are not the result of slope or elevation effects rather we suggest that they are the result of local meteorological effects on ice deposition the annual darkening and brightening of peripheral areas of the residual cap around summer solstice can be explained by the sublimation of a brighter frost layer revealing an underlying darker ice rich layer that itself either sublimes to reveal brighter material below or acts as a cold trap attracting condensation of water vapor that brightens the surface an alternative explanation invokes transport and deposition of dust on the surface from the cap interior and later removal of that dust the decrease in cap albedo and accompanying increase in near surface atmospheric stability may be related to the annual minimum of polar storm activity near northern summer solstice

tropical mountain glaciers on mars altitude dependence of ice accumulation accumulation conditions formation times glacier dynamics and implications for planetary spin axis orbital history abstract fan shaped deposits up to 166 000 km 2 in area are found on the northwest flanks of the huge tharsis montes volcanoes in the tropics of mars recent spacecraft data have confirmed earlier hypotheses that these lobate deposits are glacial in origin increased knowledge of polar latitude terrestrial glacial analogs in the antarctic dry valleys has been used to show that the lobate deposits are the remnants of cold based glaciers that formed in the extremely cold hyper arid climate of mars mars atmospheric general circulation models gcm show that these glaciers could form during periods of high obliquity when upwelling and adiabatic cooling of moist air favor deposition of snow on the northwest flanks of the tharsis montes we present a simulation of the tharsis montes ice sheets produced by a static accumulation pattern based on the gcm results and compare this with the nature and extent of the geologic deposits we use the fundamental differences between the atmospheric snow accumulation environments mass balance on earth and mars geological observations and ice sheet models to show that two equilibrium lines should characterize ice sheet mass balance on mars and that glacial accumulation should be favored on the flanks of large volcanoes not on their summits as seen on earth predicted accumulation rates from such a parameterization together with sample spin axis obliquity histories are used to show that obliquity in excess of 45 and multiple 120 000 year obliquity cycles are necessary to produce the observed deposits our results indicate that the formation of these deposits required multiple successive stages of advance and retreat before their full extent could be reached and thus imply that spin axis obliquity remained at these high values for millions of years during the late amazonian period of mars history spin axis obliquity is one of the main factors in the distribution and intensity of solar insolation and thus in determining the climate history of mars unfortunately reconstruction of past climate history is inhibited by the fact that the chaotic nature of the solution makes the calculation of orbital histories unreliable prior to about 20 ma ago we show however that the geological record combined with glacial modeling can be used to provide insight into the nature of the spin axis orbital history of mars in the late amazonian and to begin to establish data points for the geologically based reconstruction of the climate and orbital history of mars

rapid cross density ocean mixing at mid depths in the drake passage measured by tracer release diapycnal mixing across density surfaces is an important process in the global ocean overturning circulation1 2 3 mixing in the interior of most of the ocean however is thought to have a magnitude just one tenth of that required to close the global circulation by the downward mixing of less dense waters4 some of this deficit is made up by intense near bottom mixing occurring in restricted hot spots associated with rough ocean floor topography5 6 but it is not clear whether the waters at mid depth 1 000 to 3 000 metres are returned to the surface by cross density mixing or by along density flows7 here we show that diapycnal mixing of mid depth 1 500 metres waters undergoes a sustained 20 fold increase as the antarctic circumpolar current flows through the drake passage between the southern tip of south america and antarctica our results are based on an open ocean tracer release of trifluoromethyl sulphur pentafluoride we ascribe the increased mixing to turbulence generated by the deep reaching antarctic circumpolar current as it flows over rough bottom topography in the drake passage scaled to the entire circumpolar current the mixing we observe is compatible with there being a southern component to the global overturning in which about 20 sverdrups 1 sv 106 m3 s 1 upwell in the southern ocean with cross density mixing contributing a significant fraction 20 to 30 per cent of this total and the remainder upwelling along constant density surfaces the great majority of the diapycnal flux is the result of interaction with restricted regions of rough ocean floor topography

tes spectroscopic identification of a region of persistent water ice clouds on the flanks of arsia mons volcano mars 1 as part of a search for small scale spectrally anomalous regions within the mars global surveyor thermal emission spectrometer mgs tes data set we have identified a region 100 km in diameter on the southwest flanks of the volcano arsia mons that exhibits remarkable and persistent water ice cloud cover high opacity clouds by martian standards occur in this region in all of the 400 tes spectra covering this area regardless of season as well as in all of the mgs wide angle camera images of this same region we have also found evidence for similar persistent cloudiness at other local solar times of day in this region based on hubble space telescope uv imaging modeling of the tes spectra identifies the clouds as water ice and reveals average ir cloud optical depths near 0 5 and typical cloud particle sizes of 3 m the presence of persistent cloudiness in this area even during the relatively warm and cloud free season near perihelion may indicate unique local circulation processes perhaps related to orographic effects or the interaction between the global circulation and the tharsis region in general our analysis also demonstrates that through careful modeling it is possible to extend the search for unique spectral features in the tes data far into the wings of the strong 15 m co2 band

oblique terrane assembly in the late paleoproterozoic during the labradorian gothian orogeny in southern scandinavia the earliest deformation of the curved kongsberg bamble belt in norway produced a northwestward directed tectonic wedge suggesting oblique nw se collision during the labradorian gothian orogeny in southern scandinavia oblique terrane assembly with the outboard western units colliding last explains the trapping of the ostfold marstrand island arc formed at c 1760 ma between younger 1700 1600 ma terranes the apparent lack of svecofennian crust west of the trans scandinavian igneous belt and the apparent lack of labradorian gothian age crust in the british isles the labradorian of north america may have also resulted from oblique terrane assembly

daily and seasonal viking observations of martian bore wave systems a martian atmospheric phenomenon called a bore wave has been observed by the viking imaging system during late spring and early summer of two martian years in the tharsis ridge region of the planet the observational data are presented and a tentative explanation is offered for the occurrence of this feature formed by airflow and which behaves like a thermally induced diurnal katabatic breeze

moc observations of the 2001 mars planet encircling dust storm abstract from 15 september 1997 through 21 january 2006 only a single planet encircling martian dust storm was observed by mgs moc the onset of the storm occurred on 26 june 2001 l s 184 7 earliest recorded to date it was initiated in the southern mid to low latitudes by a series of local dust storm pulses that developed along the seasonal cap edge in malea and in hellas basin l s 176 2 184 4 the initial expansion of the storm though asymmetric was very rapid in all directions 3 32 m s 1 the main direction of propagation however was to the east with the storm becoming planet encircling in the southern hemisphere on l s 192 3 several distinct centers of active dust lifting were associated with the storm with the longest persisting for 86 sols syria claritas these regional storms helped generate and sustain a dust cloud haze which reached an altitude of about 60 km and a peak opacity of dust 5 0 by l s 197 0 the cloud had encircled the entire planet between 59 0 s and 60 0 n obscuring all but the largest volcanoes the decay phase began around l s 200 4 with atmospheric dust concentrations returning to nominal seasonal low levels at l s 304 0 exponential decay time constants ranged from 30 117 sols the storm caused substantial regional albedo changes darkening and brightening as a result of the redistribution removal and deposition of a thin veneer of surface dust at least 0 1 11 1 m thick it also caused changes in meteorological phenomena i e dust storms dust devils clouds recession of the polar caps and possibly surface temperatures that persisted for just a few weeks to more than a single mars year the redistribution of dust by large annual regional storms might help explain the long period 30 years between the largest planet encircling dust storms events

the reflectivity of mars at 1064 nm derivation from mars orbiter laser altimeter data and application to climatology and meteorology abstract the mars orbiter laser altimeter mola on board mars global surveyor mgs made 10 8 measurements of the reflectivity of mars at 1064 nm r 1064 by both active sounding and passive radiometry past studies of r 1064 neglected the effects of atmospheric opacity and viewing geometry on both active and passive measurements and also identified a potential calibration issue with passive radiometry therefore as yet there exists no acceptable reference r 1064 to derive a column opacity product for atmospheric studies and planning future orbital lidar observations here such a reference r 1064 is derived by seeking r 1064 m n a minnaert corrected normal albedo under clear conditions and assuming minimal phase angle dependence over darker surfaces r 1064 m n and the absolute level of atmospheric opacity were estimated from active sounding over all surfaces the opacity derived from active sounding was used to exclude passive radiometry measurements made under opaque conditions and estimate r 1064 m n these latter estimates then were re calibrated by comparison with r m n derived from hubble space telescope hst observations over areas of approximately uniform reflectivity estimates of r 1064 m n from re calibrated passive radiometry typically agree with hst observations within 10 the resulting r 1064 m n is then used to derive and quantify the uncertainties of a column opacity product which can be applied to meteorological and climatological studies of mars particularly to detect and measure mesoscale cloud aerosol structures

springwater provenance and flowpath evaluation in blue lake bonneville basin utah abstract water in utah and nevada is important for agriculture municipal use solute transport and ecosystem preservation large spring wetland systems occur on the playa margin of the bonneville basin including blue lake 15 km south of the bonneville salt flats on the utah nevada state border large spring systems have historically been studied as water budgets don t apparently balance from direct mountain front recharge nelson and mayo 2014 gardner and heilweil 2014 and others blue lake is no exception prior studies here have suggested discharge rates 0 04 0 05 km3 yr louderback and rhode 2009 greater than expected for modelled recharge in the surrounding mountain range 0 03 km3 yr three hypothesized recharge mechanisms for blue lake are tested mountain front recharge interbasinal groundwater flow and infiltration from historic lake bonneville remote sensing suggests that a conservative estimate of blue lake discharge constitutes 50 64 of modelled mountain front recharge flint et al 2011 major ions 18o 2h dissolved gases 14c 3he 4he ne ar kr xe and trace elements sr and 87sr 86sr isotopes comprehensively constrain recharge conditions water rock interactions flowpaths and groundwater provenance of this large spring system 14c signatures suggest that blue lake discharge has a transit time between 5 600 and 12 200 years older than that of fish springs noble gas concentrations in blue lake water suggest an elevated recharge temperature greater than 19 c and low salinity indicating a deep water table and high geothermal gradient in the recharge area 87sr 86sr ratios of playa margin springs are elevated from that of mid playa groundwaters springwaters from the adjacent mountain range and alluvial fill groundwater from the valley directly south of blue lake playa margin spring sr isotope values 0 713 0 714 are most similar to direct runoff from the deep creek range granodiorite outcrop 0 713 interbasinal groundwater flow in combination with mountain front recharge is best supported by chemical data rather than mountain front recharge alone or the slow discharge of regional aquifers recharged by lacustrine infiltration from lake bonneville

the vertical structure of limb hazes in the martian atmosphere abstract profiles of scattered light above the planetary limb from over 100 viking orbiter images are used to constrain the temporal and spatial behavior of earosols suspended in the martian atmosphere the data cover a wide range of seasons locations and viewing geometry providing information about the aerosol optical properties and vertical distribution the vertical resolution of the data is about 1 5 km with an absolute elevation accuracy of 1 to 4 km viking orbiter camera colibration algorithms provided reflectance accuracies to 7 absolute allowing meaningful radiometric analysis the typical atmospheric column contains one or more discrete optically thin ice like haze layers between 30 and 90 km elevation depending on season whose composition is inferred to be water ice below the detached hazes there is a continuous haze extending to the surface the continuous haze is rarely observed above 50 km and is much redder in color than the detached hazes above implying a composition that has a strong dust component the aerosol distribution exhibits a strong seasonal control inferred to be driven by the variable solar flux around the orbit of mars

north polar frontal clouds and dust storms on mars during spring and summer the complete archive of mars global surveyor mgs mars orbiter camera moc mars daily global maps mdgm are used to study north polar clouds and dust storms that exhibit frontal structures during the spring and summer ls 0 180 results show that frontal events generally follow the edge of the polar cap during spring and mid late summer with a gap in the distribution in early summer the exact duration and timing of the gap vary from year to year ten to twenty percent of spring and summer time frontal events exhibit complex morphologies distinct temperature signatures are associated with features observed in images in many but not all cases the general travel paths of the frontal events are eastward around the polar cap westward paths exist only at the edge of the polar cap in late spring early summer occasionally the paths curve toward or away from the polar cap in certain longitude sectors

alba patera mars topography structure and evolution of a unique late hesperian early amazonian shield volcano 1 new spacecraft data especially mola topography reveal important characteristics of alba patera that were either unknown or poorly resolved in previous data sets the major and consistent breaks of slope and the specific pattern of lava flows within a broad region around alba patera permit division of this area into two major parts that appear to be related to different episodes of volcanism at alba patera a low lying apron of lava flows that broadly surrounds the edifice a high standing main construct consisting of a central edifice western and eastern flanking lobes and a summit area characterized by a summit plateau and a summit dome topped by a caldera complex volcanic activity apparently began as massive effusive eruptions that formed the broad apron of lava flows followed by more focused effusive eruptions that built the central construct the construct spread gravitationally in a northerly direction to favor e w dike propagation leading to the formation of tharsis montes like flanking lobes the final stages of volcanic activity at alba patera were concentrated in the summit area forming a summit dome 400 km in diameter a caldera complex and two small shields near and inside the caldera which underwent late stage tilting and deformation the load of the newly documented summit dome may have led to the development of alba fossae reactivation of graben within tantalus fossae and tilting of the summit dome to the east a clear sequence in eruptive style is observed early massive sheet flows later tube fed flows and late shorter length and lower volume sheet flows dendritic valley networks on the northern flanks of alba patera have been interpreted to be evidence of easily erodable material of pyroclastic origin but new data suggest that these friable deposits and the valley networks may have formed instead during amazonian climate excursion periods the extensive apron of lava flows combined with the flanking lava lobes and the tharsis montes scale summit dome make alba patera much more similar to the tharsis montes than to the hesperian aged paterae the alba patera lava apron was emplaced on early hesperian ridged plains largely during the middle to late hesperian stratigraphic relationships suggest that effusive eruptions from alba patera interacted with ice rich deposits in the northern lowlands alba patera flanking lobes and the summit dome were emplaced in the earliest amazonian accompanied by late stage loading graben formation and edifice tilting

martian clouds observed by mars global surveyor mars orbiter camera we have made daily global maps that cover both polar and equatorial regions of mars for ls 135 360 and 0 111 using the mars global surveyor mgs mars orbiter camera moc red and blue wide angle swaths taken from may 1999 to january 2001 we study the seasonal distribution of condensate clouds and dust clouds during roughly 1 martian year using these daily global maps we present the development and decay of the tropical cloud belt and the polar hoods the spatial and temporal distributions of lee waves and spiral clouds and an unusual aster cloud above the volcanoes consisting of rays around a central disk like the flower the tropical cloud belt contains mostly fibrous clouds during northern spring early summer and convective clouds during middle late northern summer the detailed development and decay of the tropical cloud belt is nonuniform in longitude two distinct stormy periods in late summer precede the formation of the north and south circumpolar hoods the north polar storms in late summer resemble baroclinic frontal systems on earth but contain both dust and condensate clouds spiral clouds occur only in the northern high latitudes and only during northern spring and summer the north polar hood displays a stationary wave number two structure during the fall and winter the south polar hood has fewer streak clouds and lee wave clouds than the north polar hood during this particular year the lee wave cloud abundance in the south had two peaks in early fall and late winter and the lee wave cloud abundance in the north had one peak in early fall

winter clouds over the north martian polar cap the mars orbiter laser altimeter mola experiment carried on the mars global surveyor spacecraft has observed echoes from cloud tops on roughly 2 5 of the total data taken above 70 n over the northern winter martian polar hood from march to june 1998 sloping wavefronts are commonly seen at latitudes above 70 n implying the presence of propagating buoyancy waves since these wavefronts frequently extend from the surface up to 10 km at a time when co2 is known to be condensing on the polar surface it seems likely that the laser scattering particles consist primarily of co2 ice and that the near surface temperature lapse rate is 0 85 k km 1 set by the vapor pressure of dry ice from the observed wavelengths where available we have calculated the corresponding phase velocities some of these waves appear to be correlated with surface discontinuities and may represent lee waves

aphelion water ice cloud mapping and property retrieval using the omega imaging spectrometer onboard mars express mapping of the aphelion clouds over tharsis and retrieval of their particle size and visible opacity are made possible by the omega imaging spectrometer aboard mars express observations cover the period from my26 ls 330 degree sign to my29 ls 180 degree sign and are acquired at various local times ranging from 8am to 6pm cloud maps of the tharsis region constructed using the 3 1 m ice absorption band reveal the seasonal and diurnal evolution of aphelion clouds four distinct types of clouds are identified morning hazes topographically controlled hazes cumulus clouds and thick hazes the location and time of occurrence of these clouds are analyzed and their respective formation process is discussed an inverse method for retrieving cloud particle size and opacity is then developed and can only be applied to thick hazes the relative error of these measurements is less than 30 for cloud particle size and 20 for opacity two groups of particles can be distinguished the first group is found over flat plains and is composed of relatively small particles ranging in size from 2 to 3 5 m the second group is characterized by particle sizes of 5 m which appear to be quite constant over ls and local time it is found west of ascraeus and pavonis mons and near lunae planum these regions are preferentially exposed to anabatic winds which may control the formation of these particles and explain their distinct properties the water ice column is equal to 2 9pr m on average and can reach 5 2pr m in the thickest clouds of tharsis

detection and monitoring of h2o and co2 ice clouds on mars we have developed an observational scheme for the detection and discrimination of mars atmospheric h2o and co2 clouds using ground based instruments in the near infrared we report the results of our cloud detection and characterization study using mars near ir images obtained during the 1990 and 1993 oppositions we focused on specific wavelengths that have the potential based on previous laboratory studies of h2o and co2 ices of yielding the greatest degree of cloud detectability and compositional discriminability we have detected and mapped absorption features at some of these wavelengths in both the northern and southern polar regions of mars compositional information on the nature of these absorption features was derived from comparisons with laboratory ice spectra and with a simplified radiative transfer model of a co2 ice cloud overlying a bright surface our results indicate that both h2o and co2 ices can be detected and distinguished in the polar hood clouds the region near 3 00 m is most useful for the detection of water ice clouds because there is a strong h2o ice absorption at this wavelength but only a weak co2 ice band the region near 3 33 m is most useful for the detection of co2 ice clouds because there is a strong relatively narrow co2 ice band at this wavelength but only broad continuum h2o ice absorption weaker features near 2 30 m could arise from co2 ice at coarse grain sizes or surface dust minerals narrow features near 2 00 m which could potentially be very diagnostic of co2 ice clouds suffer from contamination by mars atmospheric co2 absorptions and are difficult to interpret because of the rather poor knowledge of surface elevation at high latitudes these results indicate that future ground based earth orbital and spacecraft studies over a more extended span of the seasonal cycle should yield substantial information on the style and timing of volatile transport on mars as well as a more detailed understanding of the role of co2 condensation in the polar heat budget

the seasonal behavior of water ice clouds in the tharsis and valles marineris regions of mars mars orbiter camera observations abstract the mars global surveyor mars orbiter camera was used to obtain global maps of the martian surface with equatorial resolution of 7 5 km pixel in two wavelength ranges blue 400 450 nm and red 575 625 nm the maps used were acquired between march 15 1999 ls 110 and july 31 2001 ls 205 corresponding to approximately one and a quarter martian years using the global maps cloud area in km2 has been measured daily for water ice clouds topographically corresponding to olympus mons ascraeus mons pavonis mons arsia mons alba patera the western valles marineris canyon system and for other small surface features in the region seasonal trends in cloud activity have been established for the three tharsis volcanoes olympus mons and alba patera olympus ascraeus and pavonis mons show cloud activity from about ls 0 220 with a peak in cloud area near ls 100 one of our most interesting observational results is that alba patera shows a double peaked feature in the cloud area with peaks at ls 60 and 140 and a minimum near ls 100 arsia mons shows nearly continuous cloud activity the altitudes of several of these clouds have been determined from the locations of the visual cloud tops and optical depths were measured for a number of them using the disort code of stamnes et al 1988 appl opt 27 2502 2509 several aspects of the observations e g cloud heights effects of increased dust on cloud activity are similar to simulations in richardson et al 2002 j geophys res 107 5064 a search for short period variations in the cloud areas revealed only indirect evidence for the diurnal cloud variability in the afternoon hours unambiguous evidence for other periodicities was not found

observations of martian ice clouds by the mars global surveyor thermal emission spectrometer the first martian year successful operation of the mars global surveyor spacecraft beginning in september 1997 ls 184 has permitted extensive observations over more than a martian year initially thin normal optical depth 0 06 at 825 cm 1 ice clouds and hazes were widespread showing a distinct latitudinal gradient with the onset of a regional dust storm at ls 224 ice clouds vanished in the southern hemisphere to reappear gradually after the decay of the storm the zonally averaged cloud opacities show little difference between the beginning and end of the first martian year a broad low latitude cloud belt with considerable longitudinal structure was present in early northern summer apparently characteristic of the northern summer season it vanished between ls 140 and 150 the latitudinal extent of this feature is apparently controlled by the ascending branch of the hadley circulation the most opaque clouds optical depth 0 6 were found above the summits of major volcanic features these showed spatial structure possibly associated with wave activity variety among low lying late morning clouds suggests localized differences in circulation and microclimates limb observations showed extensive optically thin optical depth 0 04 stratiform clouds at altitudes up to 55 km considerable latitude and altitude variations were evident in ice clouds in early northern spring ls 25 near 30 km thin clouds extended from just north of the equator to 45 n nearly to the north polar vortex a water ice haze was present in the north polar night ls 30 at altitudes up to 40 km because little dust was present this probably provided heterogeneous nucleation sites for the formation of co2 clouds and snowfall at altitudes below 20 km where atmospheric temperatures dropped to the co2 condensation point the relatively invariant spectral shape of the water ice cloud feature over space and time indicates that ice particle radii are generally between 1 and 4 m

martian dust storms 1999 mars orbiter camera observations the mars orbiter camera on board the mars global surveyor from march 9 1999 ls 107 where ls is the areocentric longitude of the sun measured in degrees from mars northern spring equinox to december 31 1999 ls 274 has obtained 7 5 km pixel 1 daily global maps of the martian surface in two wavelength bands blue 400 450 nm and red 575 625 nm visual inspection of these maps during the 1999 dust storm season has resulted in the detection of 783 dust storms ranging in size from local 102 km2 to regional 1 6 106 km2 no global storms were observed the difference in the numbers of dust storms occurring in the two hemispheres north 343 south 440 was not statistically significant fifty percent of the regional size dust storms formed as a result of the merger of two or more smaller local storms the regional storms from ls 207 to ls 223 were observed to move from the northern hemisphere into the southern hemisphere between 30 w and 50 w longitude this cross equatorial transport of dust suggests the location of the low lying southward flowing branch of the hadley circulation observations show that dust storms occur in several regions on mars at the two polar cap edges at the base of high elevation regions in the northern hemisphere near the polar hood during northern fall and at mid latitudes in both hemispheres specific regions such as solis planum and hesperia which were regions of significant dust activity in the past showed almost no dust storm activity in 1999 suggesting that regional dust sources are variable over a 20 year time frame one region of exceptional activity not noted previously was the arcadia amazonis border however other regions such as near elysium mons acidalia chryse hellas noachis argyre cimmeria and sirenum again were active dust storm regions relative dust opacities were modeled for 117 red wavelength events and ranged from 0 54 diffuse haze to 2 13 concentrated local events from the dust opacities we estimated the north polar sedimentation rate to be 6 0 10 10 4 g cm 2 yr 1 a factor of 40 smaller than previous estimates from the two 1977 global dust storms pollack et al 1979 along with the global dust mass loading 2 6 4 0 10 4 g cm 2 and cross equatorial dust mass loading 3 6 10 4 g cm 2 the 1999 cross equatorial mass dust loading suggests that the southern hemisphere subtropical latitudes require at least 2 3 martian years to replenish their dust sources before global storms can form

natural fluorinated organics in fluorite and rocks results of measurements of fluorinated compounds in gasses extracted from igneous and metamorphic rocks are reported a new extraction method analogous to a pepper mill for geological samples is described it permits extraction at low temperatures and ensures a rapid transfer of extracted gases from active surfaces to cryogenic pre concentration loop values for cf4 cf3cl cf2cl2 cfcl3 chf3 sf6 and nf3 in fluorites granites basalts and other igneous and metamorphic rocks are reported it is proposed that trifluoroacetic acid tfa that was recently discovered in various environmental archives could also origin from similar geogenic sources

a mesoscale model study of summertime atmospheric circulations in the north polar region of mars 1 the oregon state university mars mm5 was used in a comprehensive high resolution study of northern polar summertime circulations three simulations ls 120 ls 135 and ls 150 characterize the changing circulation the atmosphere is dry and model dynamics are hydrostatic a modified tes thermal inertia map provides a realistic simulation of the polar thermal environment the highest resolution nest 18 km resolves complex flows near the cap zonal mean easterlies 10 m s and zonal mean katabatic winds 5 m s near the surface are relatively steady during this study katabatic flows are shallow 300 m the easterlies are deeper 1 5 km transient eddies are very important within the first scale height they are excited by mechanisms and at locations that change dramatically during this short study period at ls 120 they form along the residual cap edge with a zonal wave number one structure producing strong excursion winds 10 15 m s that blow consistently across the cap by ls 135 strong eddies are seen to form on the northern slopes of alba patera and tharsis these eddies are quite suggestive of the large annular cloud structures seen in hubble space telescope and mars orbital camera imagery at this location and season and can traverse the high latitudes to reach the residual cap before dissipating eddies in the earlier two simulations appear to be primarily excited by energetic flows near the surface by ls 150 an early fall polar jet causes strong winter like baroclinic eddies to develop the transient eddies found in this study are probably important in the water cycle of the northern residual cap

the atmospheric temperatures over olympus mons on mars an atmospheric hot ring abstract we study the thermal fields over olympus mons separating seasons northern spring and summer against southern spring and summer and local time observations day side versus night side temperature vertical profiles retrieved from planetary fourier spectrometer on board mars express pfs mex data have been used in many orbits running north to south along a meridian passing over the top of the volcano there is evidence of a hot air on top of the volcano of two enhancement of the air temperature both north and south of it and in between a collar of air that is colder than nearby at low altitudes and warmer than nearby at high altitudes mapping together many orbits passing over or near the volcano we find that the hot air has the tendency to form an hot ring around it this hot structure occurs mostly between lt 10 00 and 15 00 and during the northern summer distance of the hot structure from the top of the volcano is about 600 km 10 of latitude the hot atmospheric region is 300 420 km 5 7 wide hot ring temperature contrasts of about 40 k occur at 2 km above the surface and decrease to 20 k at 5 km and to 10 k at 10 km the atmospheric circulation over an area of 40 40 latitudes and longitudes is affected by the topography and the presence of olympus mons 133 w 18 n we discuss also the thermal stability of the atmosphere over the selected area using the potential temperatures the temperature field over the top of the volcano shows unstable atmosphere within 10 km from the surface finally we interpret the hot temperatures around volcano as an adiabatic compression of down welling branch coming from over the top of volcano different air temperature profiles are observed in the same seasons during the night or in different seasons in northern spring summer during the night the isothermal contours do not show the presence of the volcano until we reach close to the surface very much where a thermal inversion is observed the surface temperature shows higher values by 10 k in correspondence of the scarp an abrupt altimetry variation of roughly 5 km on south 6 n and north 30 n sides of volcano during the southern spring summer on the contrary the isothermal curves run parallel to the surface even on top the volcano just like the gcm have predicted

telescopic observations of mars 1996 1997 results of the marswatch program abstract during the 1996 1997 apparition of mars marswatch and the international mars patrol imp of the mars section of the association of lunar and planetary observers alpo received 2750 observations from 70 observers in 14 countries approximately 40 of these observations are ccd images many of which were obtained through filters covering a spectral range from 330 to 820 nm in addition a large number of high quality visual observations were performed through standard color filters permitting more accurate assessments of surface and atmospheric phenomena the apparition coverage extended through 249 11 to 260 of areocentric longitude l s permitting monitoring of the northern hemisphere spring summer autumn meterological activity north polar cap npc behavior and albedo feature alterations there were few significant changes in albedo feature morphology during the 1996 1997 apparition the north polar cap rift the rima tenuis which had been observed and imaged during each aphelic apparition since 1980 was not observed perhaps due to a slowing in the npc regression after 80 l s the incidence of discrete clouds orographic and localized was higher than that predicted on the basis of the alpo imp s martian meteorology study that spanned 14 previous apparitions from 1964 to 1993 discrete clouds were more numerous than in 1993 or 1995 peaking in late northern spring 30 l s earlier than predicted the syrtis blue cloud was extensively observed and imaged between 66 and 115 l s the rate of occurrence of limb clouds was significantly lower than predicted for a given subseason their peak incidence occurred after aphelion but their frequency decreased rapidly after 105 l s nearly two martian seasons earlier than observed during previous apparitions limb hazes bright in blue and ultraviolet light were more numerous and conspicuous throughout the northern summer as predicted from the meteorology study arctic clouds increased in number around aphelion and were often large and bright during early northern summer a variable north polar hood was observed after 160 l s we find clear evidence for the existence of extensive equatorial cloud bands which became numerous between 50 and 120 l s peaking in early northern summer 105 l s and often merging into bright limb clouds these bands were more frequent and prominent in 1996 1997 than during the 1993 or 1995 apparitions and were extensively imaged in blue and ultraviolet light by both groundbased observers and by the hst

viking era water ice clouds we have spatially and temporally mapped water ice clouds on mars for 1 25 martian years using the viking infrared thermal mapper irtm data our technique compares brightness temperatures in the 11 and 20 m irtm channels utilizing the 11 m water ice absorption feature a complication arises because of the surface nonunit and wavelength dependent emissivities we developed a technique for removal of this effect using a surface thermal model we calculated brightness temperatures and their differences for the irtm channels resulting from the surface emissivity effect alone these were then subtracted from the measured brightness temperatures yielding brightness temperature differences dominated by atmospheric effects the ability to identify water ice clouds in the infrared provides potential new information about particle size and physical processes by comparing these clouds to those seen in visible wavelengths we found that water ice clouds were more widespread and frequent during the viking period than had been previously recognized with the northern spring and summer being the cloudiest periods on mars we interpret some of the identified cloudy zones as the southern and northern solstice season upwelling branches of the hadley cell although these were shifted 15 20 southward from model predictions additionally the transition between the two branches occurred later in time than in the model predictions we observed the extension of the north polar hood below 60 n in longitudes 120 200 we did not find evidence for a south polar hood north of 60 s nor any evidence for interannual variability within our limited data set

a new model to simulate the martian mesoscale and microscale atmospheric circulation validation and first results 1 the laboratoire de meteorologie dynamique lmd mesoscale model is a new versatile simulator of the martian atmosphere and environment at horizontal scales ranging from hundreds of kilometers to tens of meters the model combines the national centers for environmental prediction ncep national center for atmospheric research ncar fully compressible nonhydrostatic advanced research weather research and forecasting arw wrf dynamical core adapted to mars with the lmd general circulation model gcm comprehensive set of physical parameterizations for the martian dust co2 water and photochemistry cycles since lmd gcm large scale simulations are also used to drive the mesoscale model at the boundaries of the chosen domain of interest a high level of downscaling consistency is reached to define the initial state and the atmosphere at the domain boundaries a specific hybrid vertical interpolation from the coarse resolution gcm fields to the high resolution mesoscale domain is used to ensure the stability and the physical relevancy of the simulations used in synoptic scale mode with a cyclic domain wrapped around the planet the mesoscale model correctly replicates the main large scale thermal structure and the zonally propagating waves the model diagnostics of the near surface pressure wind and temperature daily cycles in chryse planitia are in accordance with the viking and pathfinder measurements afternoon gustiness at the respective landing sites is adequately accounted for on the condition that convective adjustment is turned off in the mesoscale simulations on the rims of valles marineris intense daytime anabatic 30 m s 1 and nighttime katabatic 40 m s 1 winds are predicted within the canyon corridors topographical channeling can amplify the wind a few kilometers above the ground especially during the night through large eddy simulations in gusev crater the model describes the mixing layer growth during the afternoon and the associated dynamics convective motions overlying gravity waves and dust devil like vortices modeled temperature profiles are in satisfactory agreement with the miniature thermal emission spectrometer mini tes measurements the ability of the model to transport tracers at regional scales is exemplified by the model s prediction for the altitude of the tharsis topographical water ice clouds in the afternoon finally a nighttime warm ring at the base of olympus mons is identified in the simulations resulting from adiabatic warming by the intense downslope winds along the flanks of the volcano the surface temperature enhancement reaches 20 k throughout the night such a phenomenon may have adversely affected the thermal inertia derivations in the region

diurnal variation and radiative influence of martian water ice clouds 1 we have identified regions in the martian tropics with anomalously warm nighttime surface temperatures the seasonal evolution of these anomalies is strongly correlated with the waxing and waning of the tropical cloud belt that is most prominent during northern hemisphere summer we attribute the anomalies to enhanced downward infrared radiation from water ice clouds the close agreement with spatial maps of atmospheric extinction derived from mars orbiter laser altimeter radiometry strongly supports this interpretation we show that a mars general circulation model simulation with radiatively active water ice clouds is able to reasonably match the observed spatial pattern and amplitude of the surface temperature anomaly the nighttime clouds are most prominent in the tharsis and arabia regions and are thicker optical depth 1 and more extensive than daytime clouds our cloud retrievals are the first to spatially map the nighttime clouds and provide an estimate of their thermal influence

fault distribution in the precambrian basement of south norway abstract mapping of the structural pattern by remote sensing methods landsat spot aerial photography potential field data and field study of selected structural elements shows that the cratonic basement of south norway is strongly affected by a regular lineament pattern that encompasses fault swarms of different orientation age style attitude and frequency albeit counting numerous fault and fracture populations the faults are not evenly distributed and n s to nne ssw nnw sse and ne se ene wsw systems are spatially dominant n s to nnw sse structures can be traced underneath the caledonian nappes to the western gneiss region in western and central south norway emphasizing their ancient roots dyke swarms of different ages are found within most of these zones also the ostfold oslo trondheim and the mandal molde lineament zones coincide with trends of sveconorwegian post collision granites we conclude that the n s trend includes the most ancient structural elements and that the trend can be traced back to the proterozoic svecofennian and sveconorwegian orogenic events some of the faults may have been active in neoproterozoic times as marginal faults of rift basins at the western margin of baltica remnants of such fault activity have survived in the cores of many of the faults belonging to this system the ancient systems of lineaments were passively overridden by the caledonian fold and thrust system and remained mostly but note entirely inactive throughout the sub cambrian peneplanation and the caledonian orogenic collapse in the silurian devonian the system was reactivated in extension from carboniferous times particularly in the permian with the formation of the oslo rift and parts of it remain active to the present albeit by decreasing extension and fault activity

themis observes possible cave skylights on mars 1 seven possible skylight entrances into martian caves were observed on and around the flanks of arsia mons by the mars odyssey thermal emission imaging system themis distinct from impact craters collapse pits or any other surface feature on mars these candidates appear to be deep dark holes at visible wavelengths while infrared observations show their thermal behaviors to be consistent with subsurface materials diameters range from 100 m to 225 m and derived minimum depths range between 68 m and 130 m most candidates seem directly related to pit craters and may have formed in a similar manner with overhanging ceilings that remain intact

receiver function analysis of the crust and upper mantle in fennoscandia isostatic implications abstract the mountains across southern norway and other margins of the north atlantic ocean appear conspicuously high in the absence of recent convergent tectonics we investigate this phenomenon with receiver functions calculated for seismometers deployed across southern fennoscandia these are used to constrain the structure and seismic properties of the lithosphere and primarily to measure the thickness and infer the bulk composition of the crust such parameters are key to understanding crustal isostasy and assessing its role or lack thereof in supporting the observed elevations our study focuses on the southern scandes mountain range that has an average elevation 1 0 km above mean sea level the crust mantle boundary moho is ubiquitously imaged and we occasionally observe structures that may represent the base of the continental lithosphere or other thermal chemical or viscous boundaries in the upper mantle the moho resides at 25 30 km depth below mean sea level in southeastern coastal norway and parts of denmark 35 45 km across the southern scandes and 50 60 km near the norwegian swedish border that section of thickest crust coincides with much of the transscandinavian igneous belt and often exhibits a diffuse conversion at the moho which probably results from the presence of a high wave speed mafic lower crust across inner fennoscandia a zone of thinned crust

mars observer camera the mars observer camera moc is a three component system one narrow angle and two wide angle cameras designed to take high spatial resolution pictures of the surface of mars and to obtain lower spatial resolution synoptic coverage of the planet s surface and atmosphere the cameras are based on the push broom technique that is they do not take frames but rather build pictures one line at a time as the spacecraft moves around the planet in its orbit moc is primarily a telescope for taking extremely high resolution pictures of selected locations on mars using the narrow angle camera areas ranging from 2 8 km 2 8 km to 2 8 km 25 2 km depending on available internal digital buffer memory can be photographed at about 1 4 m pixel additionally lower resolution pictures to a lowest resolution of about 11 m pixel can be acquired by pixel averaging these images can be much longer ranging up to 2 8 500 km at 11 m pixel high resolution data will be used to study sediments and sedimentary processes polar processes and deposits volcanism and other geologic geomorphic processes the moc wide angle cameras are capable of viewing mars from horizon to horizon and are designed for low resolution global and intermediate resolution regional studies low resolution observations can be made every orbit so that in a single 24 hour period a complete global picture of the planet can be assembled at a resolution of at least 7 5 km pixel regional areas covering hundreds of kilometers on a side may be photographed at a resolution of better than 250 m pixel at the nadir such images will be particularly useful in studying time variable features such as lee clouds the polar cap edge and wind streaks as well as acquiring stereoscopic coverage of areas of geological interest the limb can be imaged at a vertical and along track resolution of better than 1 5 km different color filters within the two wide angle cameras permit color images of the surface and atmosphere to be made to distinguish between clouds and the ground and between clouds of different composition

global patterns in cloud forms on mars abstract mariner 9 images and all viking orbiter images through july 1979 were searched for cloud forms a computer accessible catalog was assembled consisting of a classification of cloud type lee wav wave for example and properties directionality wavelength for example lee wave directionality shows a pattern and seasonal variation at high latitudes which is consistent with predictions of theoretical modeling fog and haze occurrence shows no obvious correlation with water abundance or any other simple causal factor lee waves are rare at equatorial latitudes plumes probably dust occur preferentially at locations where strong boundary layer convection is expected