temperature inversions thermal tides and water ice clouds in the martian tropics 1 we report new results on the structure and dynamics of the tropical atmosphere of mars derived from a combination of radio occultation measurements by mars global surveyor and simulations by a mars general circulation model mgcm radio occultation experiments sounded the equatorial atmosphere at latitudes of 36 n to 30 s during midsummer of the northern hemisphere ls 134 162 sampling the predawn thermal structure at a local time of 0412 elevated temperature inversions are a conspicuous feature of these observations they appear at pressures between 30 and 200 pa well above the surface and their magnitude exceeds 6 k in 34 of the temperature profiles in this latitude band the properties and spatial distribution of these elevated inversions are organized across the tropics on planetary scales inversions are strongest and occur most frequently above elevated terrain achieving a peak magnitude of 30 k near tharsis and their altitude generally increases toward the south according to mgcm simulations which closely resemble the observations these temperature inversions arise from zonally modulated thermal tides the best simulation includes an interactive hydrologic cycle which results in strong coupling between the thermal tides and radiatively active water ice clouds prominent clouds form in response to wave induced adiabatic cooling and evolve in a pattern closely correlated with the thermal structure of the tides the tides in turn are intensified by radiative forcing from the clouds this tide cloud coupling imposes strong diurnal modulation on the properties of clouds in the tropics

the tidally averaged momentum balance in a partially and periodically stratified estuary abstract observations of turbulent stresses and mean velocities over an entire spring neap cycle are used to evaluate the dynamics of tidally averaged flows in a partially stratified estuarine channel in a depth averaged sense the net flow in this channel is up estuary due to interaction of tidal forcing with the geometry of the larger basin the depth variable tidally averaged flow has the form of an estuarine exchange flow downstream at the surface upstream at depth and varies in response to the neap spring transition the weakening of the tidally averaged exchange during the spring tides appears to be a result of decreased stratification on the tidal time scale rather than changes in bed stress the dynamics of the estuarine exchange flow are defined by a balance between the vertical divergence of the tidally averaged turbulent stress and the tidally averaged pressure gradient in the lower water column in the upper water column tidal stresses are important contributors particularly during the n

thermophysical properties along curiosity s traverse in gale crater mars derived from the rems ground temperature sensor abstract the rems instrument onboard the mars science laboratory rover curiosity has measured ground temperature nearly continuously at hourly intervals for two mars years coverage of the entire diurnal cycle at 1 hz is available every few martian days we compare these measurements with predictions of surface atmosphere thermal models to derive the apparent thermal inertia and thermally derived albedo along the rover s traverse after accounting for the radiative effects of atmospheric water ice during fall and winter as is necessary to match the measured seasonal trend the rems measurements can distinguish between active sand other loose materials mudstone and sandstone based on their thermophysical properties however the apparent thermal inertias of bedrock dominated surfaces 350 550 j m 2 k 1 s are lower than expected we use rover imagery and the detailed shape of the diurnal ground temperature curve to explore whether lateral or vertical heterogeneity in the surface materials within the sensor footprint might explain the low inertias we find that the bedrock component of the surface can have a thermal inertia as high as 650 1700 j m 2 k 1 s for mudstone sites and 700 j m 2 k 1 s for sandstone sites in models runs that include lateral and vertical mixing although the results of our forward modeling approach may be non unique they demonstrate the potential to extract information about lateral and vertical variations in thermophysical properties from temporally resolved measurements of ground temperature

the water cycle and regolith atmosphere interaction at gale crater mars abstract we perform mesoscale simulations of the water cycle in a region around gale crater including the diffusion of water vapour in and out of the regolith and compare our results with measurements from the rems instrument on board the curiosity rover simulations are performed at three times of year and show that diffusion in and out of the regolith and adsorption desorption needs to be taken into account in order to match the diurnal variation of relative humidity measured by rems during the evening and night local downslope flows transport water vapour down the walls of gale crater when including regolith atmosphere interaction the amount of vapour reaching the crater floor is reduced by factors of 2 3 depending on season due to vapour diffusing into the regolith along the crater walls the transport of vapour into gale crater is also affected by the regional katabatic flow over the dichotomy boundary with the largest flux of vapour into the regolith initially occurring on the northern crater wall and moving to the southern wall by early morning upslope winds during the day transport vapour desorbing and mixing out of the regolith up crater walls where it can then be transported a few hundred metres into the atmosphere at convergence boundaries regolith atmosphere interaction limits the formation of surface ice by reducing water vapour abundances in the lower atmosphere though in some seasons ice can still form in the early morning on eastern crater walls subsurface ice amounts are small in all seasons with ice only existing in the upper few millimetres of regolith during the night the results at gale crater are representative of the behaviour at other craters in the mesoscale domain

initial results from radio occultation measurements with the mars reconnaissance orbiter a nocturnal mixed layer in the tropics and comparisons with polar profiles from the mars climate sounder abstract the mars reconnaissance orbiter mro performs radio occultation ro measurements on selected orbits generally once per day we have retrieved atmospheric profiles from two subsets of data yielding a variety of new results that illustrate the scientific value of the observations one set of measurements sounded the tropics in northern summer at a local time 1 h before sunrise some of these profiles contain an unexpected layer of neutral stability with a depth of 4 km and a pressure at its upper boundary of 160 pa the mixed layer is bounded above by a temperature inversion and below by another strong inversion adjacent to the surface this type of structure is observed near gale crater in the tharsis region and at a few other locations whereas profiles in amazonis planitia and elysium planitia show no sign of a detached mixed layer with an overlying inversion we supplemented the measurements with numerical simulations by the nasa ames mars general circulation model which demonstrate that water ice clouds can generate this distinctive type of temperature structure through their influence on radiative transfer at infrared wavelengths in particular the simulations predict the presence of a nocturnal cloud layer in the tharsis region at a pressure of 150 pa 10 km above the surface and the nighttime radiative cooling at cloud level is sufficient to produce a temperature inversion above the cloud as well as convective instability below the cloud consistent with the observations the second set of measurements sounded mid to high northern latitudes in spring when carefully coordinated observations by the mro mars climate sounder mcs are also available the differences between the ro and mcs temperature profiles are generally consistent with the expected performance of the two instruments within this set of 21 comparisons the average temperature difference is less than 1 k where the aerosol opacities are smaller than 10 3 km 1 at pressures of 10 50 pa whereas it increases to 2 k where the aerosol opacities exceed this threshold at pressures of 50 300 pa the standard deviation of the temperature difference is 2 k independent of pressure the second set of ro measurements also provides unique information about the stability of the annual co 2 cycle and the dynamics near the edge of the seasonal co 2 ice cap

the structure of mars lower atmosphere from mars express radio science mars occultation measurements 1 the mars express radio science experiment mars investigates the lower and middle atmosphere of mars between the surface and about 40 km with a very high vertical resolution more than 600 profiles of temperature pressure and neutral number density were retrieved between 2004 and 2011 covering four martian years mys 27 30 radio occultation experiments provide the unique possibility to retrieve geopotential height information to supplement temperature values the temperature field in the northern winter hemisphere displays strong temperature inversions indicating a pronounced polar warming in the northern polar night my 27 the temperature and geopotential fields imply the presence of a strong zonal jet with peak wind speeds of more than 170 m s at an altitude of about 30 km 15 pa and a latitude of 60 65 n the longitudinal temperature and geopotential fields in the southern winter of martian year 30 at latitudes between 49 and 69 s are dominated by a stationary zonal wave s 1 structure in the lower atmosphere associated meridional wind fields retrieved by assuming geostrophic balance have amplitudes up to 12 m s at the 200 pa level an investigation of small scale atmospheric waves reveals enhanced gravity wave activity in the daytime atmosphere above elevated terrain and in the winter extratropics radio occultation experiments also provide unique insight into the structure of the planetary boundary layer the deepest convective boundary layers up to 10 km are found over elevated terrain

buffering of melt oxygen fugacity by sulphur redox reactions in calc alkaline magmas calculated oxygen fugacities of magmas from lascar volcano northern chile and the 1991 eruption of mount pinatubo phillipines are seen to increase with decreasing temperature relative to the fayalite magnetite quartz buffer isopleths of constant h2s so2 at moderate pressures 2 4 kbar lie parallel to the data we conclude that magma mixing prior to eruption liberated large quantities of so2 gas by oxidation of dissolved sulphide in the mafic end member oxygen fugacity of the magmas was then buffered by reduction of this gas to h2s leading to increasingly oxidized magmas such a process might be used to explain the highly oxidized nature of other sulphur rich evolved calc alkaline magmas notably the el chichon trachyandesite

martian water ice clouds a view from mars global surveyor thermal emission spectrometer 1 we have used the mars global surveyor thermal emission spectrometer mgs tes data to map water ice clouds in the martian atmosphere in the latitude range 60 to 60 over a period of three martian years we have used the same method we have previously used on viking infrared thermal mapper data in order to allow direct comparison of the cloud behavior in the viking and mgs eras and confirmed the validity of this method by comparing it to mgs tes standard retrievals we note that the large scale behavior of water ice clouds is remarkably consistent both between the viking and the mgs eras as well as between years observed by mgs we also compare our results to water ice absorption only optical depths derived from tes data and show that correlation is best for type 2 water ice clouds

methane origin and oxygen fugacity evolution of the baogutu reduced porphyry cu deposit in the west junggar terrain china most porphyry copper deposits worldwide contain magnetite hematite and anhydrite in equilibrium with hypogene copper iron sulfides chalcopyrite bornite and have fluid inclusions with co2 ch4 that are indicative of high fo2 in contrast the baogutu porphyry cu deposit in the west junggar terrain xinjiang china lacks hematite and anhydrite contains abundant pyrrhotite and ilmenite in equilibrium with copper iron sulfides chalcopyrite and has fluid inclusions with ch4 co2 that are indicative of low fo2 the mineralized intrusive phases at baogutu include the main stage diorite stock and minor late stage diorite porphyry dikes the main stage stock underwent fractional crystallization and country rock assimilation contamination and consists of dominant diorite and minor gabbro and tonalite porphyry the country rocks contain organic carbons 0 21 0 79 wt the 13cvpdb values of the whole rocks 23 1 to 25 8 in the wall rocks suggest a sedimentary organic carbon source the 13cvpdb values of ch4 28 2 to 36 0 and co2 6 8 to 20 0 in fluid inclusions require an organic source of external carbon and equilibration of their 13cco2 ch4 values 8 2 25 0 at elevated temperatures 294 830 c suggesting a significant contribution of thermogenic ch4 mineral composition data on the main stage intrusions such as clinopyroxene hornblende biotite magnetite ilmenite sphene apatite and pyrrhotite suggest that the primary magma at baogutu was oxidized and became reduced after emplacement by contamination with country rocks mineral compositions and fluid inclusion gas compositions suggest that the redox state of the system evolved from logfo2 fmq 1 in the magma stage to logfo2 fmq in the hydrothermal stage though oxidized magma was emplaced initially assimilation contamination of carbonaceous country rocks decreased its fo2 such that exsolved fluids contained abundant ch4 and deposited a reduced assemblage of minerals

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

an analysis of the effect of topography on the martian hadley cells previous work with mars general circulation models mgcms has shown that the north south slope in martian topography causes asymmetries in the hadley cells at equinox and in the annual average to quantitatively solve for the latitude of the dividing streamline and poleward boundaries of the cells the hadley cell model of lindzen and hou was modified to include topography the model was thermally forced by newtonian relaxation to an equilibrium temperature profile calculated with daily averaged solar forcing at constant season two sets of equilibrium temperatures were considered that either contained the effects of convection or did not when convective effects were allowed the presence of the slope component shifted the dividing streamline upslope qualitatively similar to a change in season in lindzen and hou s original flat model the modified model also confirmed that the geometrical effects of the slope are much smaller than the thermal effects of the slope on the radiative convective equilibrium temperature aloft the results are compared to a simple mgcm forced by newtonian relaxation to the same equilibrium temperature profiles and the two models agree except at the winter pole near solstice the simple mgcm results for radiative convective forcing also show an asymmetry between the strengths of the hadley cells at the northern summer and northern winter solstices the hadley cell weakens with increasing slope steepness at northern summer solstice but has little effect on the strength at northern winter solstice

tidal and residual circulations in coupled restricted and leaky lagoons abstract finite element numerical modelling based on field data is used to study the tidal and tidally induced residual circulation dynamics of a coupled restricted and leaky coastal lagoon system located in the magdalen islands gulf of saint lawrence havre aux maisons lagoon hml is of a restricted nature with a neutral inlet in terms of tidal asymmetry grande entree lagoon gel is of a leaky nature with a marked ebb dominance at the inlet due to direct interactions between the main astronomical tidal constituents the imbalance caused by the different tidal filtering characteristics of both inlets combines with the internal morphological asymmetries of the system to produce a residual throughflow from hml to gel the residual circulation is also characterized by strongest values at both inlets very weak residual currents in hml deep basin and a dipole of residual eddies over the deeper areas of gel further investigations including numerical tracer experiments will be necessary to achieve a full understanding of the long term circulation of this lagoonal system

on lagrangian residual currents with applications in south san francisco bay california the lagrangian residual circulation has often been introduced as the sum of the eulerian residual circulation and the stokes drift unfortunately this definition of the lagrangian residual circulation is conceptually incorrect because both the eulerian residual circulation and the stokes drift are eulerian variables in this paper a classification of various residual variables are reviewed and properly defined the lagrangian residual circulation is then studied by means of a two stage formulation of a computer model the tidal circulation is first computed in a conventional eulerian way and then the lagrangian residual circulation is determined by a method patterned after the method of markers and cells to demonstrate properties of the lagrangian residual circulation application of this approach in south san francisco bay california is considered with the aid of the model results properties of the eulerian and lagrangian residual circulation are examined it can be concluded that estimation of the lagrangian residual circulation from eulerian data may lead to unacceptable error particularly in a tidal estuary where the tidal excursion is of the same order of magnitude as the length scale of the basin a direction calculation of the lagrangian residual circulation must be made and has been shown to be feasible

high resolution thermal inertia mapping from the mars global surveyor thermal emission spectrometer abstract high resolution thermal inertia mapping results are presented derived from mars global surveyor mgs thermal emission spectrometer tes observations of the surface temperature of mars obtained during the early portion of the mgs mapping mission thermal inertia is the key property controlling the diurnal surface temperature variations and is dependent on the physical character of the top few centimeters of the surface it represents a complex combination of particle size rock abundance exposures of bedrock and degree of induration in this work we describe the derivation of thermal inertia from tes data present global scale analysis and place these results into context with earlier work a global map of nighttime thermal bolometer based thermal inertia is presented at 1 4 per pixel resolution with approximately 63 coverage between 50 s and 70 n latitude global analysis shows a similar pattern of high and low thermal inertia as seen in previous viking low resolution mapping significantly more detail is present in the high resolution tes thermal inertia this detail represents horizontal small scale variability in the nature of the surface correlation with albedo indicates the presence of a previously undiscovered surface unit of moderate to high thermal inertia and intermediate albedo this new unit has a modal peak thermal inertia of 180 250 j m 2 k 1 s 1 2 and a narrow range of albedo near 0 24 the unit covering a significant fraction of the surface typically surrounds the low thermal inertia regions and may comprise a deposit of indurated fine material local 3 km resolution maps are also presented as examples of eolian fluvial and volcanic geology some impact crater rims and intracrater dunes show higher thermal inertias than the surrounding terrain thermal inertia of aeolian deposits such as intracrater dunes may be related to average particle size outflow channels and valleys consistently show higher thermal inertias than the surrounding terrain generally correlations between spatial variations in thermal inertia and geologic features suggest a relationship between the hundred meter scale morphology and the centimeter scale surface layer

genesis of acid sulfate alteration and au cu ag mineralization at summitville colorado the summitville au cu ag deposit occurs within a porphyritic quartz latite primarily in a zone of vuggy silica alteration characterized by leaching of all major elements except silica and iron vuggy silica is best developed between an elevation of 3 700 and 3 500 m where it occurs in irregular pipes and lenticular pods up to 70 m wide and is enclosed by up to 30 m of intense quartz alunite alteration the vuggy silica zones diminish in size with decreasing elevation and rarely exceed a width of 2 m below an elevation of 3 400 m these deep vuggy silica zones are enclosed by quartz kaolinite alteration with little or no alunite sulfide mineralization occurs primarily within the vuggy silica the sulfide assemblage changes with decreasing elevation from covellite luzonite or native gold to chalcopyrite tennantite sulfides occur lining voids or in microveinlets and are accompanied by minor kaolinitc but not by alunite gold also occurs in a near surface barite goethite jarosite assemblage that crosscuts the vuggy silica consideration of alunite kaolinitc and pyrite stability relations and of aluminum speciation at 250 degrees c indicates that a ph of 2 or below and a log f sub o 2 of 31 or 1 at 250 degrees c were necessary to produce vuggy silica alteration the chalcopyrite tennantite mineralization occurring at depth in the vuggy silica zone is indicative of less oxidizing and less acidic conditions the covellite luzonite or gold assemblage requires conditions intermediate between those necessary for vuggy silica alteration and for deep sulfide mineralization barite gold mineralization is interpreted as a near surface assemblage produced under highly acidic oxidizing conditions these textural and geochemical relationships indicate that sulfide and gold mineralization postdate the formation of vuggy silica alteration in the deposit and are not directly related to the highly acidic solutions necessary for this early acid leaching event the change from extreme acid leaching to copper sulfide and precious metal deposition may represent a transition from a magmatic vapor dominated to a liquid dominated system leading to more reducing and less acidic conditions during sulfide deposition

two mars years of clouds detected by the mars orbiter laser altimeter 1 the mars orbiter laser altimeter mola instrument operated as an atmospheric lidar system as well as an altimeter detecting absorptive clouds in northern latitudes shortly after orbit insertion in october 1997 and reflective clouds over the north polar cap at the start of the science phasing orbits in march 1998 global cloud measurements commenced with the primary mapping mission in march 1999 with nearly continuous coverage for 1 25 mars years mola tracked several dust storms culminating with a major dust storm in june 2001 reflective clouds exhibiting distinctive patterns governed by insolation and the dynamics of the atmosphere were detected at elevations up to 20 km above the surface chiefly in the polar winter night mola distinguishes cloud returns by pulse width and energy measurements unusually strong and brief reflections with minimal extinction suggest precipitation of co2 snow under supercooled conditions weaker cloud reflections occurred at all latitudes some reflective daylight clouds at low latitudes suggested convective vortices or dust devils ground fogs composed of dust and h2o ice formed at night along the seasonal frost line absorptive clouds while not resolved altimetrically tracked the advancing and receding edges of the seasonal polar caps the absorptive and reflective clouds provide a seasonal profile of atmospheric activity spanning two martian years winter reflective cloud activity declined to background levels earlier in the second year at both poles suggesting interannual warming

sulfur diffusion in rhyolite melts diffusion rates for sulfur in rhyolite melt have been measured at temperatures of 800 1100 c water contents of 0 7 3 wt and oxygen fugacities from the quartz fayalite magnetite buffer to air experiments involved dissolution of anhydrite or pyrrhotite into rhyolite melt over time scales of hours to days electron microprobe analysis was used to measure sulfur concentration profiles in the quenched glasses regression of the diffusion data in dry rhyolite melt gives dsulfur 0 05 exp 221 80rt which is one to two orders of magnitude slower than diffusion of other common magmatic volatiles such as h2o co2 and cl diffusion of sulfur in melt with 7 wt dissolved water is 1 5 to 2 orders of magnitude faster than diffusion in the anhydrous melt depending on temperature sulfur is known to dissolve in silicate melts as at least two different species s2 and s6 the proportions of which vary with oxygen fugacity despite this oxygen fugacity does not appear to affect sulfur diffusivity except under extremely oxidizing conditions this result suggests that diffusion of sulfur is controlled by one species over a large range in oxygen fugacity the most likely candidate for the diffusing species is the sulfide ion s2 re equilibration between s2 and s6 in oxidized melts must generally be slow compared to s2 diffusion in order to explain the observed results in a silicic melt undergoing degassing sulfur will tend to be fractionated from other volatile species which diffuse more rapidly this is consistent with analyses of tephra from the 1991 eruption of mount pinatubo philippines and from other high silica volcanic eruptions

zonal wavenumber three traveling waves in the northern hemisphere of mars simulated with a general circulation model abstract observations suggest a strong correlation between curvilinear shaped traveling dust storms observed in wide angle camera images and eastward traveling zonal wave number m 3 waves observed in thermal data in the northern mid and high latitudes during the fall and winter using the marswrf general circulation model we have investigated the seasonality structure and dynamics of the simulated m 3 traveling waves and tested the hypothesis that traveling dust storms may enhance m 3 traveling waves under certain conditions our standard simulation using a prescribed mgs dust scenario can capture the observed major wave modes and strong near surface temperature variations before and after the northern winter solstice the same seasonal pattern is also shown by the simulated near surface meridional wind but not by the normalized surface pressure the simulated eastward traveling 1 4 t m 3 waves are confined near the surface in terms of the temperature perturbation ep flux and eddy available potential energy and they extend higher in terms of the eddy winds and eddy kinetic energy the signature of the simulated m 3 traveling waves is stronger in the near surface meridional wind than in the near surface temperature field compared with the standard simulation our test simulations show that the prescribed m 3 traveling dust blobs can enhance the simulated m 3 traveling waves during the pre and post solstice periods when traveling dust storms are frequently observed in images and that they have negligible effect during the northern winter solstice period when traveling dust storms are absent the enhancement is even greater in our simulation when dust is concentrated closer to the surface our simulations also suggest that dust within the 45 75 n band is most effective at enhancing the simulated m 3 traveling waves there are multiple factors influencing the strength of the simulated m 3 traveling waves among those our study suggests that weaker near surface static stability larger near surface baroclinic parameter and wave form dust forcing for latitudinally extended dust storms are favorable further study is needed to fully understand the importance of these factors and others

application of three dimensional lagrangian residual transport three dimensional lagrangian residual circulation computed from an intratidal hydrodynamic model is used to drive an intertidal water quality transport model the sum of the eulerian residual and stokes drift is used as a first order approximation for the lagrangian residual current the stokes drift approximates residual currents induced by the nonlinear interactions of the tidal currents computed residual velocities show close agreement with a two dimensional vertical longitudinal analytical result the methodology is applied to chesapeake bay for the entire year of 1985 salinity computed with the intertidal transport model i e with lagrangian residuals shows good agreement with observed salinity data and that computed with the intratidal hydrodynamic model the basic effect of the stokes drift is to transport water mass e g salinity up estuary the procedures provide a practical means of interfacing intratidal hydrodynamic model information to water quality models for making long term in

a new view of near shore dynamics based on observations from hf radar abstract since 1984 the oscr hf radar system has been used in over 50 deployments to measure near shore surface currents for both scientific and engineering applications the enhanced scope resolution and accuracy of these measurements have yielded new insights into the tidal wind and density driven dynamics of the near shore zone tidal current ellipses obtained from these radar measurements have been shown to be in good aggrement with values calculated by numerical models both for the predominant constituents and also for higher harmonics coherent patterns of wind forced currents ahve been determined with strong evidence of a slab like surface response in one deployment with offshore winds blowing over relatively deep water this slab rotated clockwise at near inertial frequency strong up to 20cm s 1 persistent surface residual currents are commonly observed these are almost certainly generated by small horizontal density gradients these observed surface residuals provide ideal data for rigorous testing of 3 d numerical models with a threatened rise in sea level hf radar is well suited for observing the expected changes in the dynamics of near shore regions continuing development of these radar systems offers exciting prospects of remote sensing of both surface waves and currents future applications may extend beyond the near shore region to measurements along the shelf edge in oceanic gyres and for beach processes

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

estuarine salt conservation a lagrangian approach abstract understanding tidal and mean flow transport mechanisms that maintain the estuarine salt balance against seaward transport by river flow is one of the fundamental questions of estuarine oceanography previous salt transport studies have failed to resolve this problem for two principal methodological reasons in addition to the inherent variability of estuaries first salt transport expansions used to represent the salt balance have included a large number of terms that could not be related to any theory of estuarine circulation and whose physical meaning was thus unclear second it has proven difficult to measure small mean velocities in the presence of much larger tidal variations a new analysis method that expresses lagrangian scalar property transport in terms of time and space variations of eulerian variables is much simpler than expansions previously used and yields new insights into estuarine transport processes this approach like previous expansions is valid for narrow systems in which cross channel transport processes are weak and the ratio of tidal amplitude to mean depth is small a surface boundary condition is used to eliminate one class of troublesome terms the equivalence of the tidal cycle average transport of tidal variations in salinity and the stokes transport of mean salinity is then employed to show that the vertically integrated tidal flow plays no role in the overall salt balance that is seaward transport of salt caused by the river flow can only be balanced by landward transport resulting from correlations between shear and stratification in the mean tidal and overtide flows in a hypothetical inviscid estuary tide and overtide flows would be vertically uniform and outward fluvial salt transport could only be balanced by shear and stratification in the mean gravitational circulation in a more realistic example with strong friction the gravitational circulation would be severely damped and inward transport could only be accomplished by correlations of shear and stratification in the tide and overtide flows

discovery of a widespread low latitude diurnal co2 frost cycle on mars while the detection of co2 ice has only been reported outside the martian polar regions at very high elevation i e elysium olympus mons and the tharsis montes nighttime surface observations by the mars climate sounder on board the mars reconnaissance orbiter document the widespread occurrence of atmospherically corrected ground temperatures consistent with the presence of extensive carbon dioxide frost deposits in the dusty low thermal inertia units at middle low latitudes thermal infrared emissivities interpreted in conjunction with mass balance modeling suggest micrometer size co2 ice crystals forming optically thin layers never exceeding a few hundreds of microns in thickness i e 10 2 kg m 2 locally which is insufficient to generate a measurable diurnal pressure cycle 0 1 of the martian atmosphere atmospheric temperatures at middle low latitudes are not consistent with precipitation of co2 ice suggesting that condensation occurs on the surface the recurring growth and sublimation of co2 ice on martian dusty terrains may be an important process preventing soil induration and promoting dynamic phenomena soil avalanching and fluidization and regolith gardening maintaining a reservoir of micrometer size dust particles that are mobile and available for lifting the discovery of this diurnal co2 cycle represents an important step forward in our understanding of the way the martian atmosphere interacts with the surface

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

the redox state of pinatubo dacite and the ilmenite hematite solvus the oxidation state of the 1991 pinatubo dacite and many other oxidized silicic arc volcanic rocks has been overestimated we reproduce the compositions of magnetite and ferrian ilmenite found in pinatubo dacite by doing crystallization experiments at 780 degrees c 2 2 kbar and nno 1 7 or 0 2 log units the extra components in igneous ilmenite notably geikielite expand the solvus in a way that is not correctly accommodated in current formulations of the iron titanium oxide thermobarometer

factors controlling sulfur concentrations in volcanic apatite apatite crystals from two types of samples were analyzed by electron microprobe for 15 major and trace elements 1 apatite in h2o and s saturated experimental charges of the 1982 el chichon trachyandesite and 2 apatite in volcanic rocks erupted from 20 volcanoes the so3 contents of the experimental apatite increase with increasing oxygen fugacity from 0 04 wt in reduced charges buffered by fayalite magnetite quartz o2 fmq to 1 0 2 6 wt in oxidized charges buffered by manganosite hausmanite mnh or magnetite hematite mth the so3 contents of mnh and mth buffered apatite also generally increase with increasing pressure from 2 to 4 kbar and decreasing temperature from 950 to 800 8c the partition coefficient for so 3 between apatite and oxidized melt increases with decreasing temperature but appears to be independent of pressure apatites in volcanic rocks show a wide range of so3 contents 0 04 to 0 63 wt our sample set includes one group known to contain primary anhydrite and a second group inferred to have been free of primary anhydrite no systematic differences in apatite s contents are observed between these two groups our study was initiated to define the factors controlling s contents in apatite and to evaluate the hypothesis that high s contents in apatite could be characteristic of s rich anhydrite bearing magmas such as those erupted from el chichon in 1982 and pinatubo in 1991 this hypothesis is shown to be invalid probably chiefly a consequence of the slow intra crystalline diffusion that limits re equil ibration between early formed apatite and the evolving silicate melt contributing factors include early crystallization of most apatite over a relatively small temperature interval common late stage magmatic enrichment of s progressive oxidation during magmatic evolution and strong controls on s contents in apatite exerted by temperature and o2 pressure

on tide induced lagrangian residual current and residual transport 2 residual transport with application in south san francisco bay california the transports of solutes and other tracers are fundamental to estuarine processes the apparent transport mechanisms are convection by tidal current and current induced shear effect dispersion for processes which take place in a time period of the order of a tidal cycle however as emphasis is shifted toward the effects of intertidal processes the net transport is mainly determined by tide induced residual circulation and by residual circulation due to other processes the commonly used intertidal conservation equation takes the form of a convection dispersion equation in which the convective velocity is the eulerian residual current and the dispersion terms are often referred to as the phase effect dispersion or sometimes as the tidal dispersion the presence of these dispersion terms is merely the result of a fickian type hypothesis since the actual processes are not fickian thus a fickian hypothesis obscures the physical significance of this equation recent research results on residual circulation have suggested that long term transport phenomena are closely related to the lagrangian residual current or the lagrangian residual transport in this paper a new formulation of an intertidal conservation equation is presented and examined in detail in a weakly nonlinear tidal estuary the resultant intertidal transport equation also takes the form of a convection dispersion equation without the ad hoc introduction of phase effect dispersion in a form of dispersion tensor the convective velocity in the resultant equation is the first order lagrangian residual current the sum of the eulerian residual current and the stokes drift the remaining dispersion terms are important only in higher order solutions they are due to shear effect dispersion and turbulent mixing there exists a dispersion boundary layer adjacent to shoreline boundaries an order of magnitude estimate of the properties in the dispersion boundary layer is given the present treatment of intertidal transport processes is illustrated by an analytical solution for an amphidromic system and by a numerical application in south san francisco bay california the present formulation reveals that the mechanism for long term transport of solutes is mainly convection due to the lagrangian residual current in the interior of a tidal estuary this result also points out the weakness in the tidal dispersion formulation and explains the large variability of the observed values for tidal dispersion coefficients further research on properties of the dispersion boundary layer is needed

unraveling the martian water cycle with high resolution global climate simulations global climate modeling of the mars water cycle is usually performed at relatively coarse resolution 200 300 km which may not be sufficient to properly represent the impact of waves fronts topography effects on the detailed structure of clouds and surface ice deposits here we present new numerical simulations of the annual water cycle performed at a resolution of 1 1 60 km in latitude the model includes the radiative effects of clouds whose influence on the thermal structure and atmospheric dynamics is significant thus we also examine simulations with inactive clouds to distinguish the direct impact of resolution on circulation and winds from the indirect impact of resolution via water ice clouds to first order we find that the high resolution does not dramatically change the behavior of the system and that simulations performed at 200 km resolution capture well the behavior of the simulated water cycle and mars climate nevertheless a detailed comparison between high and low resolution simulations with reference to observations reveal several significant changes that impact our understanding of the water cycle active today on mars the key northern cap edge dynamics are affected by an increase in baroclinic wave strength with a complication of northern summer dynamics south polar frost deposition is modified with a westward longitudinal shift since southern dynamics are also influenced baroclinic wave mode transitions are observed new transient phenomena appear like spiral and streak clouds already documented in the observations atmospheric circulation cells in the polar region exhibit a large variability and are fine structured with slope winds most modeled phenomena affected by high resolution give a picture of a more turbulent planet inducing further variability this is challenging for long period climate studies

amazonian northern mid latitude glaciation on mars a proposed climate scenario recent geological observations in the northern mid latitudes of mars show evidence for past glacial activity during the late amazonian similar to the integrated glacial landsystems in the dry valleys of antarctica the large accumulation of ice many hundreds of meters required to create the observed glacial deposits points to significant atmospheric precipitation snow and ice accumulation and glacial flow in order to understand the climate scenario required for these conditions we used the lmd laboratoire de meteorologie dynamique mars gcm general circulation model which is able to reproduce the present day water cycle and to predict past deposition of ice consistent with geological observations in many cases prior to this analysis however significant mid latitude glaciation had not been simulated by the model run under a range of parameters in this analysis we studied the response of the gcm to a wider range of orbital configurations and water ice reservoirs and show that during periods of moderate obliquity 25 35 and high dust opacity sdust 1 5 2 5 broad scale glaciation in the northern mid latitudes occurs if water ice deposited on the flanks of the tharsis volcanoes at higher obliquity is available for sublimation we find that high dust contents of the atmosphere increase its water vapor holding capacity thereby moving the saturation region to the northern mid latitudes precipitation events are then controlled by topographic forcing of stationary planetary waves and transient weather systems producing surface ice distribution and amounts that are consistent with the geological record ice accumulation rates of 10 mm yr

observations and preliminary science results from the first 100 sols of msl rover environmental monitoring station ground temperature sensor measurements at gale crater we describe preliminary results from the first 100 sols of ground temperature measurements along the mars science laboratory s traverse from bradbury landing to rocknest in gale the ground temperature data show long term increases in mean temperature that are consistent with seasonal evolution deviations from expected temperature trends within the diurnal cycle are observed and may be attributed to rover and environmental effects fits to measured diurnal temperature amplitudes using a thermal model suggest that the observed surfaces have thermal inertias in the range of 265 375 j m 2 k 1 s 1 2 which are within the range of values determined from orbital measurements and are consistent with the inertias predicted from the observed particle sizes on the uppermost surface near the rover ground temperatures at gale crater appear to warm earlier and cool later than predicted by the model suggesting that there are multiple unaccounted for physical conditions or processes in our models where the mars science laboratory msl descent engines removed a mobile layer of dust and fine sediments from over rockier material the diurnal temperature profile is closer to that expected for a homogeneous surface suggesting that the mobile materials on the uppermost surface may be partially responsible for the mismatch between observed temperatures and those predicted for materials having a single thermal inertia models of local stratigraphy also implicate thermophysical heterogeneity at the uppermost surface as a potential contributor to the observed diurnal temperature cycle

topographic control of hydrogen deposits at low latitudes to midlatitudes of mars 1 correlations between the longitudinal wave number two distribution of water equivalent hydrogen weh at low latitudes to midlatitudes of mars with variations in topography surface albedo thermal inertia regional dust storms and atmospheric water vapor are explored to provide guidance in determining the mechanisms that recharge or maintain these weh reservoirs the closest match is with low thermal inertia coupled with orographic control of the present day atmospheric circulation dynamics the engine for the simulated longitudinal two wave pattern maxima in arabia and tharsis is relatively cold nighttime surface temperatures and large amplitude temperature inversions that concentrate water ice over these regions geologically recent precipitated water ice by itself is insufficient to account for the observed distribution of weh retention of precipitate by hydratable minerals is necessary while current research cannot presently identify the hydration mechanism for the weh distribution whether it be from a past obliquity present climate conditions or some convolution of both this research suggests that current climatic conditions can sustain if not emplace the observed longitudinally constrained distribution of equatorial weh

anhydrite pyrrhotite and sulfur rich apatite tracing the sulfur evolution of an oligocene andesite eagle mountain co usa abstract the oldest known occurrence of magmatic anhydrite in a shallow sub volcanic rock is at the oligocene andesitic eagle mountain volcanic center huerto formation san juan volcanic field which immediately postdates the pyrrhotite bearing fish canyon tuff estimates of intensive parameters derived from the compositions of coexisting minerals hornblende plagioclase anhydrite pyrrhotite s rich apatite augite hypersthene feti oxides indicate that the eagle mountain magma was wet oxidized and s rich it was much like k rich andesitic and dacitic anhydrite bearing magmas recently erupted from the subduction related volcanoes el chichon mt pinatubo and lascar although the oligocene geodynamic setting of the san juan volcanic field is poorly constrained and its enormous volume is not easily reconciled with an arc setting the eagle mountain occurrence emphasizes how closely some of its magmas resemble those from active continental margin arcs s rich magmas similar to the eagle mountain andesite also may have contributed to the formation of some hydrothermal ore deposits of the san juan volcanic field

recent ice ages on mars the role of radiatively active clouds and cloud microphysics global climate models gcms have been successfully employed to explain the origin of many glacial deposits on mars however the latitude dependent mantle ldm a dust ice mantling deposit that is thought to represent a recent ice age remains poorly explained by gcms we reexamine this question by considering the effect of radiatively active water ice clouds racs and cloud microphysics we find that when obliquity is set to 35 as often occurred in the past 2 million years warming of the atmosphere and polar caps by clouds modifies the water cycle and leads to the formation of a several centimeter thick ice mantle poleward of 30 in each hemisphere during winter this mantle can be preserved over the summer if increased atmospheric dust content obscures the surface and provides dust nuclei to low altitude clouds we outline a scenario for its deposition and preservation that compares favorably with the characteristics of the ldm

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

sulfur evolution of oxidized arc magmas as recorded in apatite from a porphyry copper batholith uniformly sulfur rich cores abruptly zoned to sulfur poor rims 1 to 0 2 wt so3 in apatite from the yerington batholith nevada indicate that early magma that is crystal poor oxidizing and sulfate rich evolved to sulfate poor magma via crystallization of anhydrite a mineral observed in magmas from pinatubo and el chichon we predict that the characteristic zonation to sulfur poor rims of apatite in the yerington batholith is common in other oxidized hydrous calc alkaline magmas and can be used to track cryptic anhydrite saturation as well as to monitor sulfur evolution sulfate rich arc magmas such as yerington magmas may crystallize to produce hydrothermal fluids rich in chlorine copper and sulfur and porphyry copper ores

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

harmonic analysis of tides and tidal currents in south san francisco bay california abstract water level observations from tide stations and current observations from current meter moorings in south san francisco bay south bay california have been harmonically analysed at each tide station 13 harmonic constituents have been computed by a least squares regression without inference tides in south bay are typically mixed there is a phase lag of approximately 1 h and an amplification of 1 5 from north to south for a mean semi diurnal tide because most of the current meter records are between 14 and 29 days only the five most important harmonics have been solved for east west and north south velocity components the eccentricity of tidal current ellipse is generally very small which indicates that the tidal current in south bay is strongly bidirectional the analyses further show that the principal direction and the magnitude of tidal current are well correlated with the basin bathymetry patterns of eulerian residual circulation deduced from the current meter data show an anticlockwise gyre to the west and a clockwise gyre to the east of the main channel in the summer months due to the prevailing westerly wind opposite trends have been observed during winter when the wind was variable

comagmatic granophyric granite in the fish canyon tuff colorado implications for magma chamber processes during a large ash flow eruption the 27 8 ma fish canyon tuff a vast ash flow sheet 5000 km 3 of uniform phenocryst rich dacite is representative of monotonous intermediate eruptions from a magma chamber that lacked compositional gradients sparse small fragments of comagmatic granophyre in late erupted tuff and postcaldera lava having mineral compositions indistinguishable from phenocrysts in the tuff and precaldera lava like rocks record complex events in the fish canyon chamber just prior to eruption sanidine phenocrysts in the granophyre preserve zoning evidence of mingling with andesitic magma then shattering by decompression and volatile loss accompanying early fish canyon eruptions before overgrowth by granophyre the textural and chemical disequilibria indicate that the eruption resulted from batholith scale remobilization of a shallow subvolcanic chamber contrary to previous interpretations of magma storage and phenocryst growth in the lower crust

a seasonally recurrent annular cyclone in mars northern latitudes and observations of a companion vortex we study a seasonally recurrent cyclone and related cloud phenomena observed on mars at ls 120 latitude 60 n and longitude 90 w from images obtained with cameras in different spacecraft between 1995 and 2018 a remarkable double cyclone formed in 2012 and we present a detailed study of its dynamics using images from mars express and mars reconnaissance orbiter obtained between june 6 and july 9 a double cyclone was also observed in 2006 and 2008 in other martian years the primary cyclone showed an annular cloud morphology with a large water ice cloud observed eastward of it the cyclones have a size of 600 800 km with a cloud free core of a radius 100 300 km tangential velocities measured from cloud tracking in 2012 images are 5 20 ms 1 at 10 km altitude and dc moved eastwards with a velocity of 4 ms 1 during its lifetime of one month the vortices grow in the morning hours but with the increasing insolation as the sol progresses a part of the clouds evaporate the winds weaken and the vortices lose coherence this phenomenon forms under high temperature gradients in a region with a large north south topographic slope and has been recurrent each martian year between 1995 and 2018 we argue the interest of studying its changing properties each martian year in order to explore their possible relationship to the state of the martian atmosphere at ls 120