fast and accurate estimation of solar irradiance on martian slopes 1 a general parameterization is proposed in this study to calculate in a mars like dusty atmosphere the solar irradiance reaching an inclined surface assuming the value in the horizontal case is known complete monte carlo radiative transfer calculations using the ockert bell et al 1997 dust optical properties enable the validation of the method for mars the total shortwave flux reaching the surface is composed of three contributions direct incoming flux reflected flux by surrounding terrains and scattered flux by the atmospheric dust the main difficulty is the parameterization of the latter component we show that the scattered flux reaching the slope can be expressed by a physically based simple formula involving one empirical coupling matrix and two vectors accounting for the scattering properties and the geometrical settings the final result is a computationally efficient parameterization with an accuracy in most cases better than 5 w m 2 such a fast and accurate method to calculate solar irradiance on martian slopes should they be topographical surfaces or solar panels is of particular interest in a wide range of applications such as remote sensing measurements geological and meteorological models and mars exploration missions design

ground truth from the opportunity rover for mars thermal inertia data 1 the temperature of the martian surface has been measured by a number of spacecraft and numerical models of the surface thermal response constrain the near surface physical properties the results allow inferences regarding the surface layer and help determine potential hazards for landed spacecraft however thermal models generally do not incorporate the degree of surface complexity that is seen from landers here we examine potential contributions to the thermal response along the opportunity rover s traverse by using ground truth in conjunction with orbiter data from the themis instrument on mars odyssey we show that the size distribution of the ubiquitous hematite spherules varies in a way that is consistent with expectations from orbiter data secondly exposures of bedrock along opportunity s traverse have no observable effect on the bulk thermal response seen from orbit these field observations are an important step toward improving understanding of the physical composition of the martian surface

simulations of northern hemisphere ice sheet retreat sensitivity to physical mechanisms involved during the last deglaciation a 3 dimensional thermomechanical ice sheet model is used to simulate the evolution of the geometry of northern hemisphere ice sheets through the last deglaciation the ice sheet model is forced by a time evolving climatology provided by the linear interpolation through time of climate snapshots simulated by the lmd5 3 atmospheric general circulation model agcm at different periods of the last deglaciation 21 15 9 6 and 0 kyr bp the agcm is driven by insolation atmospheric co2 content ice sheet configuration and sea surface temperatures although our approach is able to produce the complete continental ice retreat our simulated deglaciation presents a phase lag with reconstructions based on observational evidences this suggests that physical mechanisms related to climate forcing and or ice sheet internal dynamics are not properly represented the influence of millennial scale forcing feedback mechanisms between ice sheet elevation and surface mass balance and parameterization of the ice flow is also tested through a set of sensitivity experiments the rapid variability has a strong impact on the evolution of the ice volume because of nonlinear effects in temperature mass balance relationships fennoscandia appears to be strongly sensitive to the small scale ice sheet instability both ice sheets are to some extent sensitive to an increased basal sliding

wind related features in gusev crater mars 1 gusev crater has a complex history beginning with its formation by an impact in the noachian period and subsequent evolution including erosion and deposition associated with ma adim vallis which cut through gusev crater from the south various wind related features are found on the crater floor including albedo patterns bedforms such as barchan dunes and elongated hills possibly reflecting erosion by the wind comparisons of the orientations of these features with predictions from global and atmospheric models show wind patterns as functions of season and time of day strongest global winds occur out of the southeast in the late fall and early winter and appear to be responsible for the formation of a large dark streak that drapes 100 km across the crater floor on an intermediate scale bright wind streaks correlate with nighttime winds that flow into the crater from the rim and outlying high areas these streaks are interpreted to be deposits of dust settled from the atmosphere during times of positive atmospheric static stability smaller features include various dark streaks and duneforms the orientations of which are inferred to represent local zones of high wind shear surface stress these features also tend to correlate with strong afternoon upslope winds caused by the uneven heating of the atmosphere across the crater thus the large dark streak reflects global scale wind patterns the smaller dark features and duneforms represent flow of strong winds out of the crater in the afternoon and the small bright streaks represent deposition of dust associated with nighttime flow of wind into the crater the correlation between the wind regime predicted by the models and the orientations of the aeolian features gives confidence that the models are essentially correct because gusev is a prime candidate landing site for landers including the mars exploration rovers understanding the interplay of the atmosphere and the surface including the erosion and deposition of windblown particles is important in assessments of the science potential for these missions despite the abundance of wind related features on the floor of gusev only about 1 2 of the proposed landing ellipse area is covered with organized bedforms e g dunes although mantles of sand and dust are also likely to be present on the basis of an analysis of random landing points within the ellipse traverse distances to ridges ejecta from small craters and other potential sources of rocks are within 150 m traverse distance for 95 of the touchdown points

structure and dynamics of the convective boundary layer on mars as inferred from large eddy simulations and remote sensing measurements the structure of the martian convective boundary layer bl is decribed by means of a novel approach involving both modelling and data analysis mars express radio occultation ro temperature profiles are compared to large eddy simulations less performed with the martian mesoscale model the model combines the martian radiative transfer soil and surface layer schemes designed at laboratoire de meteorologie dynamique lmd with the most recent version of the weather research and forecast wrf fully compressible non hydrostatic dynamical core the key roles of the vertical resolution and to lesser extent of the domain horizontal extent have been investigated to ensure the robustness of the les results the dramatic regional variations of the bl depth are quantitatively reproduced by the martian les intense bl dynamics are found to underlie the measured depths up to 9 km vertical speed up to 20 m s 1 heat flux up to 2 7 k m s 1 and turbulent kinetic energy up to 26 m2 s 2 under specific conditions both the model and the measurements show a distinctive positive correlation between surface topography and bl depth our interpretation is that in the tenuous co2 martian near surface environment the daytime bl is to first order controlled by the infrared radiative heating fairly independent of elevation which implies a simple correlation between the bl potential temperature and the inverse pressure pressure effect no prominent pressure effect is in action on earth where sensible heat flux dominates the bl energy budget both ro observations and numerical simulations confirm the terrain following behaviour of near surface temperature on mars induced by the dominant radiative influence the contribution of the martian sensible heat flux is not negligible and results in a given isotherm in the bl being comparatively closer to the ground at higher surface elevation the strong radiative control of the martian convective bl implies a generalised formulation for the bl dimensionless quantities based on this formulation and the variety of simulated bl depths by the les new similarity relationships for the martian convective bl in quasi steady midday conditions are derived rigorous comparisons between the martian and terrestrial bl and fast computations of the mean martian bl turbulent statistics are now made possible by such similarity laws copyright 2010 royal meteorological society

martian high latitude permafrost depth and surface cover thermal inertia distributions 1 martian high latitudes have thermal properties consistent with an extensive high thermal inertia permafrost layer near the surface surface cover thermal inertias and permafrost depths at martian high latitudes 50 80 n s are derived from thermal emission spectrometer tes data and compared with previously published water ice depths determined from the mars odyssey neutron spectrometer mons the depth to the permafrost layer is correlated with surface cover thermal inertia albedo and latitude in general agreement with predicted trends of water ice stability comparison of permafrost depths with water ice rich layer depths derived from mons data displays good qualitative agreement although a divergence is present at greater burial depths this disparity may be due to the presence of hydrated minerals at shallow depths or a lower than expected permafrost thermal inertia corresponding with low water ice concentrations at greater depths surface cover thermal inertias are greater in the northern high latitudes than in the south and differences between these and previous results will have significant effects on the predicted depth of martian water ice stability several regions in the northern hemisphere display high surface cover thermal inertia associated with possible receding water ice deposits that are shallow enough to influence diurnal surface temperatures significant lateral and vertical heterogeneity in water ice distributions are present and the martian regolith is likely more complicated than can be described by simple two layered models and a single mode of water ice emplacement

onset and migration of spiral troughs on mars revealed by orbital radar the northern polar cap of mars containing enough water to cover the entire planet to a depth of several metres features two major landforms that stand above all others these are the enormous canyon chasma boreale and a series of spiral troughs the processes leading to their formation have remained unclear now two papers in this issue present detailed histories of both systems john holt and colleagues use penetrating radar imagery from mars reconnaissance orbiter s radar sounder to show that depositional processes rather than a catastrophic event formed the chasma boreale isaac smith and john holt use mars reconnaissance orbiter data to rule out erosional cutting of polar ice as the cause of the central troughs and instead conclude that they too are largely depositional having migrated polewards and upwards in elevation in the past two million years a pinwheel array of deep troughs has been one of the most perplexing features of the north polar layered deposits on mars many ideas have been put forward about how it formed but there is as yet no consensus here penetrating radar has been used to rule out erosional cutting as a mechanism for the formation of the array instead it is concluded that the troughs are largely depositional in origin and have migrated to the poles and upwards in elevation over the past two million years or so the landscape of the north polar layered deposits of mars npld is dominated by a pinwheel array of enigmatic spiral troughs1 the troughs have intrigued planetary scientists since the mariner 9 spacecraft returned the first close up image in 1972 but conclusive evidence of their origin has remained elusive debate continues regarding all aspects of the troughs including the possibility that they have migrated2 3 4 5 their age in relation to the current npld surface6 and whether they are fundamentally erosional6 7 or constructional2 4 features the troughs are probably related to climatic processes2 8 yet the nature of this relationship has remained a mystery previous data characterizing only the exposed nlpd surface were insufficient to test these hypotheses here we show that the central spiral troughs initiated after deposition of three quarters of the npld quickly reached a stable morphology and migrated approximately 65 kilometres poleward and 600 metres in altitude over the past two million years or so our radar stratigraphy rules out hypotheses of erosional incision post dating deposition6 7 9 10 and instead largely validates an early hypothesis for constructional trough migration2 3 4 5 with wind transport and atmospheric deposition as dominant processes these results provide hard constraints for palaeo climate models and a new context for evaluating imagery spectral data and now radar sounding data the better to understand the link between orbital parameters and climate the role of climate in shaping the polar ice of mars and eventually the age of the polar deposits themselves8 11 12 13

a comparative study of daytime thermally induced upslope flow on mars and earth abstract several characteristics of thermally induced mesoscale upslope flow on mars and its comparison with that on earth were investigated using both analytical and numerical model approaches the conclusions obtained from the analytical and the numerical evaluations for mars are generally in agreement the main conclusions are i the intensity of the martian summer daytime upslope flow with a moderate slope reaches nearly 10 m s 1 and its depth is about 5 km ii the longwave radiation flux divergence heating within the lower boundary layer of mars has a nonnegligible contribution to the intensity of the upslope flows and iii on mars the values of upslope wind speed are typically about 2 5 times larger than on earth under similar conditions the depth of the daytime upslope flow and the air temperature increase near the surface are 3 to 4 times larger the vertical eddy exchange coefficient for heat and momentum is about 10 times larger on mars

physical properties of the mars exploration rover landing sites as inferred from mini tes derived thermal inertia 1 the miniature thermal emission spectrometer mini tes on board the two mars exploration rovers provides the first opportunity to observe thermal properties from the martian surface relate these properties to orbital data and perform soil conductivity experiments under martian conditions the thermal inertias of soils bedforms and rock at each landing site were derived to quantify the physical properties of these features and understand geologic processes occurring at these localities the thermal inertia for the gusev plains rock target bonneville beacon 1200 j m 2 k 1 s 1 2 is consistent with a dense basaltic rock but the rocks at the columbia hills have a lower thermal inertia 620 j m 2 k 1 s 1 2 suggesting that they have a volcaniclasic origin bedforms on the floors of craters at both landing sites have thermal inertias of 200 j m 2 k 1 s 1 2 consistent with a particle diameter of 160 m this diameter is comparable to the most easily moved grain size in the current atmosphere on mars suggesting that these bedforms may have formed under current atmospheric conditions along the meridiani plains the thermal inertia is lower than that derived from tes and thermal emission imaging system themis orbital data this discrepancy is not well understood mini tes derived thermal inertias at gusev along a 2 5 km traverse follow trends in thermal inertia measured from orbit with tes and themis however along the traverse there are variability and mixing of particle sizes that are not resolved in the orbital thermal inertia data due to meter scale processes that are not identifiable at larger scales

improved general circulation models of the martian atmosphere from the surface to above 80 km we describe a set of two new generation general circulation models of the martian atmosphere derived from the models we originally developed in the early 1990s the two new models share the same physical parameterizations but use two complementary numerical methods to solve the atmospheric dynamic equations the vertical resolution near the surface has been refined and the vertical domain has been extended to above 80 km these changes are accompanied by the inclusion of state of the art parameterizations to better simulate the dynamical and physical processes near the surface boundary layer scheme subgrid scale topography parameterization etc and at high altitude gravity wave drag in addition radiative transfer calculations and the representation of polar processes have been significantly improved we present some examples of zonal mean fields from simulations using the model at several seasons one relatively novel aspect previously introduced by wilson 1997 is that around northern winter solstice the strong pole to pole diabatic forcing creates a quasi global angular momentum conserving hadley cell which has no terrestrial equivalent within such a cell the coriolis forces accelerate the winter meridional flow toward the pole and induce a strong warming of the middle polar atmosphere down to 25 km this winter polar warming had been observed but not properly modeled until recently in fact thermal inversions are generally predicted above one and often both poles around 60 70 km however the mars middle atmosphere above 40 km is found to be very model sensitive and thus difficult to simulate accurately in the absence of observations

thermal inertia mapping of mars from 60 s to 60 n twenty micrometer brightness temperatures are used to derive the thermal inertia for 81 of the martian surface between latitudes 60 these data were acquired by the two viking infrared thermal mappers in 1977 and 1978 following the two global dust storms of 1977 the spatial resolution used is 2 in latitude by 2 in longitude and the total range in derived inertia is 1 to 15 10 3 cal cm 2 sec 12 k 1 the distribution of thermal inertia is strongly bimodal with all values of thermal inertia less than 4 10 3 cal cm 2 sec 12 k 1 being associated with three disjoint bright regions mostly in the northern hemisphere sufficient dust is raised in global storms to provide fine material adequate to produce these low inertia areas but the specific deposition mechanism has not been defined at the low resolution used no complete exposures of clean rock were found there is some tendency for darker material to be associated with higher thermal inertia although the trend is far from one to one the distribution of high and low inertia areas is sufficiently nonrandom to produce a variation in whole disk brightness temperature with central meridian longitude this variation and the change in surface kinetic temperature associated with dust storms are factors in establishing the whole disk brightness temperature at radio and infrared wavelengths and will be important for those who use mars as a calibration source

meteorological predictions for 2003 mars exploration rover high priority landing sites 1 the mars regional atmospheric modeling system is used to predict meteorological conditions that are likely to be encountered by the mars exploration rovers at several proposed landing sites during entry descent and landing seven areas five of which contain specific high priority landing ellipses are investigated hematite two sites isidis planitia elysium planitia two sites valles marineris and gusev crater the last two locations are in regions of extreme topography and the local and regional thermal circulations that result are equally extreme horizontal wind speeds near the floor of valles marineris exceed 50 ms 1 vertical velocities near the walls exceed 40 ms 1 and penetrate 10 km in altitude above the rim of the canyon thermal convection is suppressed within valles marineris by subsidence that forms in response to the upslope flows along the canyon walls wind magnitudes at gusev crater are approximately one third of those at the canyon but horizontal wind shear is greater deep convective thermals are noted at the relatively flat hematite site where 10 ms 1 updrafts rising to heights of 5 km are not uncommon during the midafternoon linearly organized convective updrafts superimposed on upslope circulations dominate over most of isidis planitia hexagonal and linearly organized convection predominates at elysium planitia afternoon circulations at all sites pose some risk significant risk in some cases to entry descent and landing most of the atmospheric hazards are not evident in current observational data and general circulation model simulations and can only be ascertained through mesoscale modeling of the region

simulation of surface meteorology at the pathfinder and vl1 sites using a mars mesoscale model 1 the fifth generation penn state ncar mesoscale model mm5 has been adapted to study circulations in the martian atmosphere the nasa ames mars general circulation model gcm provides initial and boundary conditions the meteorology of this mars mm5 the osu mmm5 is compared with pathfinder and viking lander 1 vl1 data for late northern summer the mmm5 uses an equator crossing semiglobal polar stereographic mother domain significantly reducing the boundary reflections inherent in martian mesoscale simulations using two way nests simultaneous simulations of two regions are performed 1 chryse planitia mars pathfinder mpf vl1 and 2 the central chasmas of valles marineris simulations are hydrostatic and dry the mmm5 uses the same atmospheric radiation package as the gcm but a much enhanced near surface vertical resolution and a different planetary boundary layer pbl scheme model topography thermal inertia and surface albedo maps have all been developed using the most recent data from the mars global surveyor mgs mars orbiter laser altimeter mola and thermal emission spectrometer tes experiments the diurnal cycles of surface air temperature surface pressure and surface wind all show improvement in comparison with the gcm for certain regions the local surface pressure tidal amplitudes are strongly dependent on the resolution of the model and or the topography vl1 and mpf are in such a region the diurnal cycles of wind are complex and for many locations the near surface winds are dominated by slope flows of multiple scales comparison with data indicates that resolving these slope flows is very important for simulating the diurnal wind cycle at specific locations these slope flows dramatically influence the diurnal surface pressure cycle

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

daily temperature variations on mars the viking infrared thermal mapper irtm has measured the infrared brightness temperature of mars for more than a full martian year the daily variation of the 20 m brightness temperature can be predicted to within 5 k for most of the martian surface during any season if the radiometric albedo and the thermal inertia of the model are allowed to increase with increasing atmospheric dust opacity however for approximately 32 of the martian surface area no values of thermal inertia or albedo can fit the thermal observations these temperature anomalies isolate one large region on mars which connects the low thermal inertia regions of arabia tharsis and elysium the anomalies do not correlate with elevation geologic units morphology or atmospheric dust content all regions with lambert albedo less than 0 18 can be well fit with the standard thermal model but all areas with albedo greater than 0 28 are anomalous there is a strong inverse correlation between the magnitude of the anomaly and the thermal inertia this correlation indicates that some surface property is responsible for the anomaly in the anomalous region the observed temperatures are warmer in the morning cooler late in the afternoon and decrease more slowly during the night than the viking model temperatures of all the physical processes likely to occur on mars but not included in the viking thermal model only a layered soil can explain the observations a low thermal inertia layer covering a high thermal inertia material will heat up quickly in the morning and cool down quickly in the afternoon at night the high thermal inertia material will moderate the temperature a possible interpretation for the layering deduced from the irtm observations is a layer of aeolian deposited dust about one thermal skin depth thick 1 to 4 cm covering a duricrust because dust accumulates in some areas after every global dust storm the duricrust must be actively forming a one thermal skin depth dust layer covering a duricrust is compatible with viking lander observations irtm spectral observations and viking orbiter imaging

the mars limited area model and simulations of atmospheric circulations for the phoenix landing area and season of operation 1 the mars limited area model mlam has been used to simulate martian northern polar atmospheric circulation phenomena during the planned season of the phoenix lander touching down on the surface ls 76 initial and boundary conditions are from thermal emission spectrometer observations assimilated via the united kingdom mars general circulation model the higher resolution north pole centric nestings grid lengths about 17 30 km and 8 5 15 km respectively resolve phenomena such as shallow mesoscale katabatic drainage flows spiraling out of the cold polar dome strong valley winds out of chasma borealis and diurnal slope winds embedded on the easterly basic flow e g at phoenix landing area d there conditions appear to be mild for mars and baroclinic activity is low low level jets with wind speeds exceeding 20 m s are however possible but they are most likely nocturnal and would hence not endanger the early afternoon landing of phoenix dust lifting is predicted for strong wind areas near the landing area b where baroclinic activity appears to be high and in the general area of the landing area d primarily east of it

volcanic spreading and lateral variations in the structure of olympus mons mars the olympus mons volcano on mars is notable not only for its immense height and width but also for substantial asymmetries in its structure the gently sloped northwest flank extends to a much greater distance from the central caldera complex than the more steeply sloped southeast flank furthermore the northwest flank exhibits lower flank extensional faults whereas the southeast shows upper flank compressional terraces and lower flank upthrust blocks however both the northwest and southeast flanks exhibit characteristic concave upward profiles and steep bounding scarps in contrast to other sectors the nw se asymmetries are aligned with the regional slope from the tharsis rise but an understanding of the underlying causes has remained elusive we use particle dynamics models of growing spreading volcanoes to demonstrate that these flank structures could reflect the properties of the basement materials underlying olympus mons we find that basal slopes alone are insufficient to produce the observed concave upward slopes and asymmetries in flank extent and deformation style that are observed at olympus mons instead lateral variations in basal friction are required these variations are most likely related to the presence of sediments transported and preferentially accumulated downslope from the tharsis rise such sediments likely correspond to ancient phyllosilicates clays recently discovered by the mars express mission

the martian slope winds and the nocturnal pbl jet abstract the summertime martian pbl diurnal wind variation slope winds and the nocturnal low level jets were studied using prandtl s theory a mesoscale numerical model and viking lander observations during moderate prevailing large scale flow nocturnal jets were simulated that were rather similar to those on earth they were mainly caused by inertial oscillation after sunset with some contribution from the slope wind effects over sloping regions which are very common in mars during weak large scale flow shallow nocturnal drainage flows with strong vertical shear developed over the cold martian slopes at middle and high latitudes these katabatic winds tended to turn to flow along the slope by dawn due to the coriolis force for sufficiently steep slopes near surface drainage winds could reach considerable speeds in contrast the typical afternoon upslope winds were vertically homogeneous up to 2 3 km and weak only 1 3 m s 1 in magnitude even over relatively steep large scale slopes

thermal behavior of horizontally mixed surfaces on mars abstract current methods for deriving thermal inertia from spacecraft observations of planetary brightness temperature generally assume that surface properties are uniform for any given observation or co located set of observations as a result of this assumption and the nonlinear relationship between temperature and thermal inertia sub pixel horizontal heterogeneity may yield different apparent thermal inertia at different times of day or seasons we examine the effects of horizontal heterogeneity on mars by modeling the thermal behavior of various idealized mixed surfaces containing differing proportions of either dust sand duricrust and rock or slope facets at different angles and azimuths latitudinal effects on mixed surface thermal behavior are also investigated we find large several 100 j m 2 k 1 s 1 2 diurnal and seasonal variations in apparent thermal inertia even for small 10 admixtures of materials with moderately contrasting thermal properties or slope angles together with similar results for layered surfaces mellon m t putzig n e 2007 lunar planet sci xxxviii abstract 2184 this work shows that the effects of heterogeneity on the thermal behavior of the martian surface are substantial and may be expected to result in large variations in apparent thermal inertia as derived from spacecraft instruments while our results caution against the over interpretation of thermal inertia taken from median or average maps or derived from single temperature measurements they also suggest the possibility of using a suite of apparent thermal inertia values derived from single observations over a range of times of day and seasons to constrain the heterogeneity of the martian surface

the mars regional atmospheric modeling system model description and selected simulations the mars regional atmospheric modeling system mrams is introduced and selected model results are presented and compared with landed meteorological data when possible mrams is descended from a nonhydrostatic earth mesoscale and cloud scale model that is widely used for forecasting weather and simulating atmospheric systems over complex terrain mesoscale models such as mrams are ideal tools for making use of the high resolution data sets arriving from mars global surveyor experiments simulation of the mars pathfinder mpf landing site at lsd 142 using 1 2 degree mars orbiter laser altimeter mola derived topography and thermal emission spectrometer thermal inertia is shown to be in good agreement with observed near surface temperature pressure and wind direction simulations of topographically induced thermal circulations and mountain induced gravity waves are shown to be consistent with theory and earlier studies that tie large amplitude mountain waves to strong winds capable of producing dust streaks and local dust lifting events a large eddy simulation of the convective boundary layer provides estimates of vertical profiles of heat flux momentum flux turbulent kinetic energy and vertical velocity variance the model results suggest that the martian atmosphere is roughly two to three times more turbulent than the terrestrial atmosphere during the afternoon but fluxes are roughly an order of magnitude smaller due to the lower density dust devillike circulations are also predicted in the large eddy simulation finally a simulation that examines atmosphere surface interactions near big crater is discussed predicted surface wind stress patterns are consistent with aeolian processes inferred through mars orbiter camera imagery of big crater located near the mpf landing site c 2001 academic press

apparent thermal inertia and the surface heterogeneity of mars abstract thermal inertia derivation techniques generally assume that surface properties are uniform at horizontal scales below the footprint of the observing instrument and to depths of several decimeters consequently surfaces with horizontal or vertical heterogeneity may yield apparent thermal inertia which varies with time of day and season to investigate these temporal variations we processed three mars years of mars global surveyor thermal emission spectrometer observations and produced global nightside and dayside seasonal maps of apparent thermal inertia these maps show broad regions with diurnal and seasonal differences up to 200 j m 2 k 1 s 1 2 at mid latitudes 60 s to 60 n and 600 j m 2 k 1 s 1 2 or greater in the polar regions we compared the seasonal mapping results with modeled apparent thermal inertia and created new maps of surface heterogeneity at 5 resolution delineating regions that have thermal characteristics consistent with horizontal mixtures or layers of two materials the thermal behavior of most regions on mars appears to be dominated by layering with upper layers of higher thermal inertia e g duricrusts or desert pavements over fines prevailing in mid latitudes and upper layers of lower thermal inertia e g dust covered rock soils with an ice table at shallow depths prevailing in polar regions less common are regions dominated by horizontal mixtures such as those containing differing proportions of rocks sand dust and duricrust or surfaces with divergent local slopes other regions show thermal behavior that is more complex and not well represented by two component surface models these results have important implications for mars surface geology climate modeling landing site selection and other endeavors that employ thermal inertia as a tool for characterizing surface properties

the low level katabatic jet height versus monin obukhov height in this short note we discuss a long standing problem in modelling the atmospheric boundary layer abl over complex terrain namely an excessive use of the monin obukhov length scale lmo this issue becomes increasingly relevant with the ever increasing resolution of numerical weather prediction and climate models which typically use lmo in one way or another for parametrizing the surface layer or at least for formulating the lower boundary conditions hence inevitably the models under represent a significant part of the mesoscale flow variability we focus here on the stable abl over land in particular sloped cooled flows however a qualitatively similar reasoning applies to the corresponding unstable abl we show that for sufficiently stratified flows over moderately sloped surfaces monin obukhov scaling is inadequate for describing the basic abl dynamics which is often governed by katabatic and drainage flows copyright 2007 royal meteorological society

near tropical subsurface ice on mars near surface perennial water ice on mars has been previously inferred down to latitudes of about 45 and could result from either water vapor diffusion through the regolith under current conditions or previous ice ages precipitations in this paper we show that at latitudes as low as 25 in the southern hemisphere buried water ice in the shallow 1 m subsurface is required to explain the observed surface distribution of seasonal co2 frost on pole facing slopes this result shows that possible remnants of the last ice age as well as water that will be needed for the future exploration of mars are accessible significantly closer to the equator than previously thought where mild conditions for both robotic and human exploration lie copyright 2010 by the american geophysical union

geologically recent tectonic volcanic and fluvial activity on the eastern flank of the olympus mons volcano mars 1 we show evidence of very recent 25 40 myr geologic activity on the eastern flank of olympus mons volcano that includes a suite of fluvial channel networks volcanic emplacement of lava flows and dikes and tectonic wrinkle ridges and troughs processes the combination and youth of these features confirms the importance of geological activity continuing to the present on mars

the construction of chasma boreale on mars the northern polar cap of mars containing enough water to cover the entire planet to a depth of several metres features two major landforms that stand above all others these are the enormous canyon chasma boreale and a series of spiral troughs the processes leading to their formation have remained unclear now two papers in this issue present detailed histories of both systems john holt and colleagues use penetrating radar imagery from mars reconnaissance orbiter s radar sounder to show that depositional processes rather than a catastrophic event formed the chasma boreale isaac smith and john holt use mars reconnaissance orbiter data to rule out erosional cutting of polar ice as the cause of the central troughs and instead conclude that they too are largely depositional having migrated polewards and upwards in elevation in the past two million years the chasma boreale is a large canyon 500 km long up to 100 km wide and nearly 2 km deep that cuts into the north polar layered deposits on mars quite how it formed has been unclear however new penetrating radar imagery has now been used to show that depositional processes rather than catastrophic events were responsible the polar layered deposits of mars contain the planet s largest known reservoir of water ice1 2 and the prospect of revealing a detailed martian palaeoclimate record3 4 but the mechanisms responsible for the formation of the dominant features of the north polar layered deposits npld are unclear despite decades of debate stratigraphic analyses of the exposed portions of chasma boreale a large canyon 500 km long up to 100 km wide and nearly 2 km deep have led most researchers to favour an erosional process for its formation following initial npld accumulation candidate mechanisms include the catastrophic outburst of water5 protracted basal melting6 erosional undercutting7 aeolian downcutting7 8 9 and a combination of these processes10 here we use new data from the mars reconnaissance orbiter to show that chasma boreale is instead a long lived complex feature resulting primarily from non uniform accumulation of the npld the initial valley that later became chasma boreale was matched by a second equally large valley that was completely filled in by subsequent deposition leaving no evidence on the surface to indicate its former presence we further demonstrate that topography existing before the npld began accumulating influenced successive episodes of deposition and erosion resulting in most of the present day topography long term and large scale patterns of mass balance achieved through sedimentary processes rather than catastrophic events ice flow or highly focused erosion have produced the largest geomorphic anomaly in the north polar ice of mars

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

modification of δ d values in eastern nevada granitoid rocks spatially related to thrust faults stable isotope data have been determined for 13 mesozoic and tertiary plutons in eastern nevada and nearby utah in the southern snake range of eastern nevada where relations are best exposed and have been most intensively studied d 18o and apparent k ar ages depend on proximity to the snake range decollement where stresses resulting from late movement on the decollement have caused cataclasis of oligocene 37 ma granitoid rock 18o d and k ar age values as low as 2 5 155 and 18 ma respectively have been determined where there has been no cataclasis 18o values of jurassic cretaceous and oligocene granitoid rocks are apparently unaffected but both d values and k ar ages have been modified for distances of tens of meters below the decollement results similar to those in the southern snake range have been observed in other eastern nevada granitoid rocks spatially related to regional thrust faults as in the kern mountains the toana range and the northern egan range in each of these areas cataclasis or deformation of granitoid rocks has resulted in lowered 18o d and k ar age values where there has been no cataclasis or deformation 18o values are unaffected but both d and k ar age values have been lowered by stresses resulting from postcrystallization movement along overlying thrust faults many of the plutons discussed have not been deeply eroded and spatially related thrust faults crop out where thrust faults are not in evidence and the granitoid rocks give d values lower than about 130 along with spuriously low k ar age results modification of the d and k ar age values may have been caused by stresses related to late movement along an overlying now eroded thrust fault

simulation of the atmospheric thermal circulation of a martian volcano using a mesoscale numerical model mesoscale 100 km atmospheric phenomena are ubiquitous on mars as revealed by mars orbiter camera images numerical models provide an important means of investigating martian atmospheric dynamics for which data availability is limited but the resolution of general circulation models which are traditionally used for such research is not sufficient to resolve mesoscale phenomena to provide better understanding of these relatively small scale phenomena mesoscale models have recently been introduced here we simulate the mesoscale spiral dust cloud observed over the caldera of the volcano arsia mons by using the mars regional atmospheric modelling system our simulation uses a hierarchy of nested models with grid sizes ranging from 240 km to 3 km and reveals that the dust cloud is an indicator of a greater but optically thin thermal circulation that reaches heights of up to 30 km and transports dust horizontally over thousands of kilometres

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

the impact of martian mesoscale winds on surface temperature and on the determination of thermal inertia radiative control of surface temperature is a key characteristic of the martian environment and its low density atmosphere here we show through meteorological modeling that surface temperature can be far from radiative equilibrium over numerous sloping terrains on mars where nighttime mesoscale katabatic winds impact the surface energy budget katabatic circulations induce both adiabatic atmospheric heating and enhancement of downward sensible heat flux which then becomes comparable to radiative flux and acts to warm the ground through this mechanism surface temperature can increase up to 20 k one consequence is that warm signatures of surface temperature over slopes observed through infrared spectrometry cannot be systematically associated with contrasts of intrinsic soil thermal inertia apparent thermal inertia maps retrieved thus far possibly contain wind induced structures another consequence is that surface temperature observations close to sloping terrains could allow the validation of model predictions for martian katabatic winds provided contrasts in intrinsic thermal inertia can be ruled out the thermal impact of winds is mostly discussed in this paper in the particular cases of olympus mons lycus sulci and terra meridiani but is generally significant over any sloped terrains in low thermal inertia areas it is even general enough to apply under daytime conditions thereby providing a possible explanation for observed afternoon surface cooling and to ice covered terrains thereby providing new insights on how winds could have shaped the present surface of mars