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

chloride bearing materials in the southern highlands of mars chlorides commonly precipitate during the evaporation of surface water or groundwater and during volcanic outgassing spectrally distinct surface deposits consistent with chloride bearing materials have been identified and mapped using data from the 2001 mars odyssey thermal emission imaging system these deposits are found throughout regions of low albedo in the southern highlands of mars geomorphologic evidence from orbiting imagery reveals these deposits to be light toned relative to their surroundings and to be polygonally fractured the deposits are small

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

surficial properties in gale crater mars from mars odyssey themis data abstract we examine the nature of the surface layer in gale crater as determined from high resolution thermal and visible mars odyssey thermal emission imaging system themis data as well as how our conclusions compare to past analyses at themis resolution the thermal surface structure is dominated by local control thus providing us with detailed images that contain thermophysical information as well using these data sets we have created a map of the area defining units based primarily on their geomorphology as determined from the daytime thermal and visible images and then using the nighttime thermal data to interpret the nature of the surface layer within each unit seven units have been defined i partially blanketed knobby plateaus ii crater walls with terrain similar to that on the plateaus on the upper half and exposed rocky surfaces on the lower half iii v three floor units with varying combinations of bedrock and indurated and or particulate deposits vi sand sheets and vii a central mound consisting of indurated and or rocky material forming layers terraces and slides covered by particulate material that tapers in thickness downslope additionally dozens of channels have been observed on the crater walls and central mound the results indicate that aeolian processes have played a major role in shaping much of the present surface layer within gale and may still be active today because of the dramatic size and structure of gale the winds are most likely controlled by the local topography additionally the presence and frequency of channels within gale bolster hypotheses involving aqueous episodes in the history of the crater

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

laboratory studies of electrical potential during rock failure we have investigated electrical potential and acoustic emissions signals associated with rock deformation five rock types were studied clashach bentheim and darley dale sandstones all quartz rich and a seljadur basalt and portland limestone both quartz free both air dry and the rocks were tested in distilled water shallow crustal conditions were simulated in a triaxial rock deformation cell with a confining pressure simulating depth of 40 mpa pore pressures ranging 5 35 mpa and strain rates 10 7 10 4 s 1 precursory electric potential signals prior to failure were observed in both saturated and dry samples of the quartz rich sandstones but only observed in the water saturated quartz free rocks co seismic electrical signals were obtained in all tests providing strong evidence that two of the main sources for precursory and co seismic signals are the piezoelectric and electrokinetic phenomena lowering the strain rate resulted in an increase in the number of acoustic emissions the pore volume changes during compaction and dilatancy remained approximately constant for all strain rates streaming potential generated by fluid flow across the sample was also measured at different stages of deformation the potential signals increased with the pore pressure gradient c 2005 elsevier ltd all rights reserved

overview of the mars science laboratory mission bradbury landing to yellowknife bay and beyond the mars science laboratory mission reached bradbury landing in august 2012 in its first 500 sols the rover curiosity was commissioned and began its investigation of the habitability of past and present environments within gale crater curiosity traversed eastward toward glenelg investigating a boulder with a highly alkaline basaltic composition encountering numerous exposures of outcropping pebble conglomerate and sampling aeolian sediment at rocknest and lacustrine mudstones at yellowknife bay on sol 324 the mission turned its focus southwest beginning a year long journey to the lower reaches of mt sharp with brief stops at the darwin and cooperstown waypoints the unprecedented complexity of the rover and payload systems posed challenges to science operations as did a number of anomalies operational processes were revised to include additional opportunities for advance planning by the science and engineering teams

a model of thermal conductivity for planetary soils 2 theory for cemented soils 1 a numerical model of heat conduction through particulate media made of spherical grains cemented by various bonding agents is presented the pore filling gas conductivity volume fraction and thermal conductivity of the cementing phase are tunable parameters cement fractions 0 001 0 01 in volume have small effects on the soil bulk thermal conductivity a significant conductivity increase factor 3 8 is observed for bond fractions of 0 01 to 1 in volume in the 1 to 15 bond fraction domain the conductivity increases continuously but less intensely 25 100 conductivity increase compared to a 1 bond system beyond 15 of cements the conductivity increases vigorously and the bulk conductivity rapidly approaches that of bedrock the composition of the cements i e conductivity has little influence on the bulk thermal inertia of the soil especially if the volume of bond 10 these results indicate that temperature measurements are sufficient to detect cemented soils and quantify the amount of cementing phase but the mineralogical nature of the bonds and the typical grain size are unlikely to be determined from orbit on mars a widespread surface unit characterized by a medium albedo 0 19 0 26 and medium high thermal inertia 200 600 j s 0 5 m 2 k 1 has long been hypothesized to be associated with a duricrust the fraction of cement required to fit the thermal data is less than 1 5 by volume this small amount of material is consistent with orbital observations confirming that soil cementation is an important factor controlling the thermal inertia of the martian surface

global duricrust on mars analysis of remote sensing data global remote sensing data for mars are analyzed to obtain a simple self consistent model for the surface layer the data sets discussed include radar cross section measurements at several wavelengths radio whole disk thermal emission observations at two wavelengths the global distribution of thermal inertia deviations of diurnal temperatures from those of a homogeneous model and thermal spectral estimates of surface rock abundance and of the thermal inertia of the nonrocky component of the surface the data sets which most constrain the interpretation are the rock abundance map and the correlation of thermal inertia with radar cross section these require the rock abundance to not vary significantly from place to place and simultaneously require the density and thermal inertia of the fines to vary in a consistent manner the simplest model which can explain all of the data involves a global case hardened crust duricrust which varies spatially in its degree of formation in general low thermal inertia regions have a poorly developed crust and highinertia regions have a well developed crust there are however regions that consist of coarse particles and which do not fit this model e g chryse this model is consistent with the ages of low inertia regions and with aeolian mechanisms for their development the duricrust is thought to form via the mobilization of salt ions within a layer of water adsorbed within the regolith and its formation may be associated with the exchange of water between the regolith and atmosphere which occurs on the 105 and 106 year time scale

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

soil like deposits observed by sojourner the pathfinder rover most of the soil like materials at the pathfinder landing site behave like moderately dense soils on earth with friction angles near 34 39 and are called cloddy deposits cloddy deposits appear to be poorly sorted with dust sized to granule sized mineral or rock grains they may contain pebbles small rock fragments and clods thin deposits of porous compressible drifts with friction angles near 26 28 are also present drifts are fine grained cohesions of both types of deposits are small there may be indurated soil like deposits and or coated or crusted rocks cloddy deposits may be fluvial sediments of the ares tiu floods but other origins such as ejecta from nearby impact craters should be considered drifts are probably dusts that settled from the martian atmosphere remote sensing signatures of the deposits inferred from rover observations are consistent with those observed from orbit and earth

thermal emission imaging system themis infrared observations of atmospheric dust and water ice cloud optical depth 1 the mars odyssey spacecraft entered into martian orbit in october 2001 and after successful aerobraking began mapping in february 2002 thermal infrared images taken by the thermal emission imaging system themis on board the odyssey spacecraft allow for the quantitative retrieval of atmospheric dust and water ice aerosol optical depth data collected so far cover late northern winter spring and summer ls 330 160 during this period themis observed the decay of a regional dust storm a number of local dust storms along the edge of the retreating north polar cap and the growth of the low latitude aphelion water ice cloud belt data from themis complements the concurrent mars global surveyor thermal emission spectrometer tes data by sampling a later local time 1400 lt for tes versus 1600 1730 lt for themis and by observing at much higher spatial resolution comparison of water ice optical depth in the aphelion cloud belt from themis and tes shows a significantly higher optical depth in the late afternoon themis than in the early afternoon tes

a habitable fluvio lacustrine environment at yellowknife bay gale crater mars the curiosity rover discovered fine grained sedimentary rocks which are inferred to represent an ancient lake and preserve evidence of an environment that would have been suited to support a martian biosphere founded on chemolithoautotrophy this aqueous environment was characterized by neutral ph low salinity and variable redox states of both iron and sulfur species carbon hydrogen oxygen sulfur nitrogen and phosphorus were measured directly as key biogenic elements by inference phosphorus is assumed to have been available the environment probably had a minimum duration of hundreds to tens of thousands of years these results highlight the biological viability of fluvial lacustrine environments in the post noachian history of mars

pancam multispectral imaging results from the spirit rover at gusev crater panoramic camera images at gusev crater reveal a rock strewn surface interspersed with high to moderate albedo fine grained deposits occurring in part as drifts or in small circular swales or hollows optically thick coatings of fine grained ferric iron rich dust dominate most bright soil and rock surfaces spectra of some darker rock surfaces and rock regions exposed by brushing or grinding show near infrared spectral signatures consistent with the presence of mafic silicates such as pyroxene or olivine atmospheric observations show a steady decline in dust opacity during the mission and astronomical observations captured solar transits by the martian moons phobos and deimos as well as a view of earth from the martian surface

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

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 formation of infilled craters on mars evidence for widespread impact induced decompression of the early martian mantle flat floored craters have long been recognized on mars with early work hypothesizing a sedimentary origin more recently high resolution thermal inertia measurements show that these craters contain some of the rockiest materials on the planet inconsistent with poorly consolidated sedimentary materials in this study the distribution physical properties morphology and thermal inertia and composition of these craters are thoroughly investigated over the entire planet the majority of the 2800 rocky crater floors identified are concentrated in the low albedo 0 1 0 17 cratered southern highlands these craters were infilled at 3 5 ga and are associated with the highest thermal inertia values and some of the most mafic materials identified on the planet although several processes may have led to the formation of the crater floors the most likely scenario is volcanic infilling through fractures created by the impact event the primitive magma source directly results from decompression melting of the martian mantle by the removal of the crustal material excavated by the impactor volcanic infilling of craters by decompression melting appears to only have occurred in early martian history when the lithosphere was still relatively thin and the thermal gradient was high this process was widespread and responsible for the eruption of significant volumes of primitive material inside and likely outside of craters impact induced decompression melting of the martian mantle accounts for the unusual infilling of martian craters and is a widespread planetary process that has gone previously undocumented

global distribution of bedrock exposures on mars using themis high resolution thermal inertia 1 we investigate high thermal inertia surfaces using the mars odyssey thermal emission imaging system themis nighttime temperature images 100 m pixel spatial sampling for this study we interpret any pixel in a themis image with a thermal inertia over 1200 j m 2 k 1 s 1 2 as bedrock which represents either in situ rock exposures or rock dominated surfaces three distinct morphologies ranked from most to least common are associated with these high thermal inertia surfaces 1 valley and crater walls associated with mass wasting and high surface slope angles 2 floors of craters with diameters 25 km and containing melt or volcanics associated with larger high energy impacts and 3 intercrater surfaces with compositions significantly more mafic than the surrounding regolith in general bedrock instances on mars occur as small exposures less than several square kilometers situated in lower albedo 350 j m 2 k 1 s 1 2 and relatively dust free dust cover index 0 95 regions however there are instances that do not follow these generalizations most instances are concentrated in the southern highlands with very few located at high latitudes poleward of 45 n and 58 s suggesting enhanced mechanical breakdown probably associated with permafrost overall mars has very little exposed bedrock with only 960 instances identified from 75 s to 75 n with likely 3500 km 2 exposed representing 1 ofthe total surface area these data indicate that mars has likely undergone large scale surface processing and reworking both chemically and mechanically either destroying or masking a majority of the bedrock exposures on the planet

the opportunity rover s athena science investigation at meridiani planum mars the mars exploration rover opportunity has investigated the landing site in eagle crater and the nearby plains within meridiani planum the soils consist of fine grained basaltic sand and a surface lag of hematite rich spherules spherule fragments and other granules wind ripples are common underlying the thin soil layer and exposed within small impact craters and troughs are flat lying sedimentary rocks these rocks are finely laminated are rich in sulfur and contain abundant sulfate salts small scale cross lamination in some locations provides evidence for deposition in flowing liquid water we interpret the rocks to be a mixture of chemical and siliciclastic sediments formed by episodic inundation by shallow surface water followed by evaporation exposure and desiccation hematite rich spherules are embedded in the rock and eroding from them we interpret these spherules to be concretions formed by postdepositional diagenesis again involving liquid water

the spirit rover s athena science investigation at gusev crater mars the mars exploration rover spirit and its athena science payload have been used to investigate a landing site in gusev crater gusev is hypothesized to be the site of a former lake but no clear evidence for lacustrine sedimentation has been found to date instead the dominant lithology is basalt and the dominant geologic processes are impact events and eolian transport many rocks exhibit coatings and other characteristics that may be evidence for minor aqueous alteration any lacustrine sediments that may exist at this location within gusev apparently have been buried by lavas that have undergone subsequent impact disruption

lunar equatorial surface temperatures and regolith properties from the diviner lunar radiometer experiment 1 the diviner lunar radiometer experiment onboard the lunar reconnaissance orbiter has measured solar reflectance and mid infrared radiance globally over four diurnal cycles at unprecedented spatial and temporal resolution these data are used to infer the radiative and bulk thermophysical properties of the near surface regolith layer at all longitudes around the equator normal albedos are estimated from solar reflectance measurements normal spectral emissivities relative to the 8 m christiansen feature are computed from brightness temperatures and used along with albedos as inputs to a numerical thermal model model fits to daytime temperatures require that the albedo increase with solar incidence angle measured nighttime cooling is remarkably similar across longitude and major geologic units consistent with the scarcity of rock exposures and with the widespread presence of a near surface layer whose physical structure and thermal response are determined by pulverization through micrometeoroid impacts nighttime temperatures are best fit using a graded regolith model with a 40 increase in bulk density and an eightfold increase in thermal conductivity adjusted for temperature occurring within several centimeters of the surface

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

surface energy budget and thermal inertia at gale crater calculations from ground based measurements the analysis of the surface energy budget seb yields insights into soil atmosphere interactions and local climates while the analysis of the thermal inertia i of shallow subsurfaces provides context for evaluating geological features mars orbital data have been used to determine thermal inertias at horizontal scales of 104 m2 to 107 m2 here we use measurements of ground temperature and atmospheric variables by curiosity to calculate thermal inertias at gale crater at horizontal scales of 102 m2 we analyze three sols representing distinct environmental conditions and soil properties sol 82 at rocknest rck sol 112 at point lake pl and sol 139 at yellowknife bay ykb our results indicate that the largest thermal inertia i 452 j m 2 k 1 s 1 2 si units used throughout this article is found at ykb followed by pl with i 306 and rck with i 295 these values are consistent with the expected thermal inertias for the types of terrain imaged by mastcam and with previous satellite estimations at gale crater we also calculate the seb using data from measurements by curiosity s rover environmental monitoring station and dust opacity values derived from measurements by mastcam the knowledge of the seb and thermal inertia has the potential to enhance our understanding of the climate the geology and the habitability of mars

surficial geologic surveys of gale crater and melas chasma mars integration of remote sensing data abstract remote sensing observations of gale crater and melas chasma are synthesized to better understand the present surface layer in these two scientifically interesting regions data sets analyzed include geologic maps mars orbiter laser altimeter mola elevation thermal emission spectrometer tes albedo tes thermal inertia mola residual pulse width tes rock abundance and viking and mars orbiter camera images using these data sets we constrain the properties of and processes acting on the present surface and create self consistent models for the surface layer surface properties within gale crater are variable and complex and interpreting the surface layer is not straightforward observations indicate that aeolian processes have shaped some of the intracrater surface but other areas do not comply with this model and have counterintuitive surface characteristics in contrast aeolian activity appears to have played a large role in shaping the present day physical structure of all surfaces in melas chasma and is reflected in the remote sensing data sets here we summarize our analysis and discuss the surface attributes as determined from these data sets

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

temperature dependent thermal inertia of homogeneous martian regolith 1 past studies of the thermophysical properties of the martian surface layer have assumed temperature independent thermal inertia which is a function of the material density specific heat and bulk conductivity in this paper we evaluate the temperature driven variations of these quantities for particulated and cemented material under martian conditions of atmospheric pressure and temperature temperature driven density variations are negligible the specific heat of a basaltic material is strongly influenced by the temperature 75 increase from 150 to 315 k inducing significant variations of the thermal inertia the thermal conductivity of uncemented martian regolith is weakly controlled by the solid phase conductivity and strongly controlled by the gaseous phase conductivity as a result the conductivity of the solid phase i e composition temperature is unimportant whereas medium to large variations 30 50 of the bulk conductivity are associated with temperature induced fluctuations of the pore filling gas conductivity overall the thermal inertia of uncemented martian soils is predicted to vary significantly 80 throughout the range of the observed surface temperatures in the case of cemented soils the contribution of the gas conductivity is generally small and the solid phase i e grains and cement conductivity i e composition temperature becomes more important consequently the magnitude of the thermal inertia change for cemented soils is variable and smaller than that predicted for uncemented materials 10 50 large diurnal and seasonal temperature variations only occur within the top material and most of the near surface regolith does not experience large thermal inertia variations the shapes of modeled diurnal temperature curves are not significantly modified e g the 0200 lt martian local time apparent thermal inertia of uncemented regolith is up to 15 lower than the average daily inertia of the top material thermally derived grain sizes are usually based on conductivity measurements operated at room temperature or above where the thermal inertia and specific heat are higher than on mars implying that grain size predictions for mars are currently underestimated however in situ observations by the mars exploration rovers and thermal conductivity modeling suggest that this underestimation is not significant

pyloniid stratigraphy a new tool to date tropical radiolarian ooze from the central tropical indian ocean pyloniid stratigraphy a faunal abundance variation stratigraphic tool similar to cycladophora davisiana stratigraphy employed at high latitudes is found to work well for tropical radiolarian ooze the relationship between the spatial distribution of 25 modern radiolarian groups in surface sediments and monsoonal surface salinity from the central indian ocean is analyzed among them pyloniids exhibit the potential to serve in the same way as the c davisiana stratigraphy down core temporal variation of pyloniids in a sediment core is compared with i the sum of the earth s orbital eccentricity axial tilt and precession etp ii solar insolation at the core site 8 s and 65 n and iii the specmap 18o stratigraphy the multi taper mtm spectral analysis of pyloniids for the last 485 ka in a core aas 2 3 reveals significant climatic cycles at the eccentricity 100 ka tilt 41 ka and precession 23 ka bands cross spectral analyses suggest coherent 90 pyloniid cycles lag both the etp and june insolation 65 n by 9 ka at 100 ka eccentricity and are almost 2 ka in phase with 41 ka tilt and 23 ka precession cycles coherent pyloniid cycles lag specmap 18o by 14 ka at 41 ka tilt and 6 ka at 23 ka precession while they lag insolation at the core site by 7 ka at 100 ka lead 18 ka at 41 ka and show in phase relation with 23 ka cycles marginal lead of 10 ka by etp and insolation over pyloniids at 100 ka eccentricity and in phase relation at 41 ka tilt and 23 ka precession cycles suggest pyloniids variation could be used as a tool to derive age models in tropical radiolarian ooze during the late neogene quaternary