orbital observations of contemporary dune activity in endeavor crater meridiani planum mars 1 although aeolian landforms are pervasive on mars evidence for contemporary activity has been limited the next major campaign for the mars exploration rover opportunity is the investigation of the 20 km diameter endeavor crater 6 km to southeast of the rover s position as of december 2010 we present evidence from orbital imagery that eight aeolian bed forms 14 000 m2 in endeavor crater have been active within the past decade 2001 2009 at a spatial scale that should be directly observable by opportunity from the crater rim two dunes appear to show translational migration 10 20 m but all dunes indicate erosion to be the dominant process with up to 100 sediment removal thermophysical properties of these dunes are consistent with very fine to fine sand sizes the particle sizes most easily moved by the martian atmosphere the dunes that show the most surface change have a rippled appearance without well defined slip faces based on their morphology elliptical shape we classify them as dome dunes mesoscale atmospheric modeling is employed to provide insight into the atmospheric forcing of this aeolian system the major wind regimes from modeling are consistent with observations of wind streaks sand streamers ripples and slip faces of regional dune fields although modeled wind speeds are insufficient to move sand the translation and erosion of these dunes constitutes the largest contemporary movement of sand sized sediment reported on mars to date and demonstrates that endeavor crater has been subject to wind profiles exceeding the threshold velocity at the surface daily seasonally and or episodically in the recent past

reflectivity modeling of a ground penetrating radar profile of a saturated fluvial formation major horizons in radar reflection profiles may correlate with contacts between stratigraphic units or with structural breaks such as fault surfaces minor reflections may be caused by clutter or in some cases may indicate material properties or structure within stratigraphic units in this study we examine the physical basis for major and minor reflections observed in a shallow unconfined fluvial aquifer near boise idaho u s a we compare a 2d profile from a surface ground penetrating radar reflection transect with the 1d modeled reflection profiles at three wells adjacent to the surface reflection profile the 1d models are based on dielectric constant and electrical conductivity values from borehole logs and vertical radar profile data reflections at the water table capillary fringe at the base of a sand filled channel and at the base of two sand rich lenses in a cobble dominated unit are recognizable in the surfacereflection profile and in all 1d reflectivity models less prominent reflections in stratigraphic units occur in both the surface profile model and the reflectivity model although such minor reflections are not correlated easily general similarities in their presence and location indicate that sometimes the reflections may be useful for recognizing internal facies structure or character

latitude dependent nature and physical characteristics of transverse aeolian ridges on mars 1 narrow angle images from the mars orbiter camera moc have revealed the common occurrence of small scale 100 m wavelength bright transverse aeolian ridges tars on the surface of mars moc images were used to assess the broad distribution of tars from 90 n to 90 s between 180 e and 240 e to investigate their relationship to latitude elevation thermal inertia geologic units local slopes and surface roughness out of 5112 examined images from the primary mission 520 10 contain evidence of tars 92 of the images with tars are located between 50 latitude and very few occur in the middle to upper latitudes or polar regions of either hemisphere tars are observed at elevations from 5 km to 3 km with the highest frequency 26 between 1 and 0 km there is no systematic relationship between the distribution of tars and global thermal inertia measurements most tars occur in geologic units associated with the channel system materials 39 and the olympus mons aureole 33 at a length scale of 1 85 km pixel the average local slopes for images with and without tars are 1 92 and 1 36 respectively of the parameters investigated the latitudinal trend of tars in both hemispheres appears to be predominantly related to surface roughness with a positive linear correlation between the surface roughness of geologic units and frequency of tars r2 0 87 factors affecting the semiglobal distribution of tars are likely related to the climate and wind regimes in which they formed but do not provide definitive evidence for either saltation or reptation formation mechanisms

wind regime sediment transport and landscape dynamics at a mars analogue site in the andes mountains of northwestern argentina abstract the puna plateau of northwestern argentina is a promising region for analogue investigations of martian aeolian processes owing to its high altitude low atmospheric pressure aridity geology and widespread granular and bedrock aeolian landforms despite a growing body of research about the region s enigmatic aeolian landforms little is known about the contemporary aeolian environment processes and landscape dynamics to address this gap we used a combination of modelled weather data satellite imagery and field measurements to characterize the wind regime aeolian sediment transport and allied surface changes the study focused on the campo de piedra pomez cpp a volcanic landscape with a variety of mars analogue landforms gravel mantled megaripples yardangs ventifacts periodic bedrock ridges and aeolian rat tails modelled weather data from the european center for medium range forecasting s era interim reanalysis dataset confirm the contemporary dominance of northwesterly winds in this region consistent with the primary orientation of yardangs these data also indicate the presence of less frequent southeasterly winds which may explain why re entrant profiles are observed on the southeast flanks of a small portion of the yardang population and why some aeolian rat tails point to the northwest observations from multi temporal satellite imagery indicate that deposition and displacement of small sediment patches overlying ignimbrite bedrock is relatively common across the region samples retrieved from sediment traps deployed over one year in the region suggest a broad range of particle densities are mobilized by wind which implies a wide range of wind speed for fluid entrainment conventional aeolian transport models do not consider the effects of particle density variations on transport processes however in areas with multiple density sediment present our results point towards a need for aeolian models to consider density when quantifying and qualifying sediment transport

early views of the martian surface from the mars orbiter camera of mars global surveyor high resolution images of the martian surface at scales of a few meters show ubiquitous erosional and depositional eolian landforms dunes sandsheets and drifts are prevalent and exhibit a range of morphology composition inferred from albedo and age as seen in occurrences of different dune orientations at the same location steep walls of topographic depressions such as canyons valleys and impact craters show the martian crust to be stratified at scales of a few tens of meters the south polar layered terrain and superposed permanent ice cap display diverse surface textures that may reflect the complex interplay of volatile and non volatile components low resolution regional views of the planet provide synoptic observations of polar cap retreat condensate clouds and the lifecycle of local and regional dust storms

recent near surface wind directions inferred from mapping sand ripples on martian dunes abstract the high resolution imaging science experiment hirise provides the capability to obtain orbital images of mars that are of sufficient resolution to record wind ripple patterns on the surfaces of sand dunes ripple patterns provide valuable insights into aeolian erosion and deposition on earth and mars in this study we develop a systematic mapping procedure to examine sand ripple orientations and create surface process maps to evaluate the recent wind flow over the dunes as well as the interplay of wind and dune shape by carefully examining the morphology of the dunes and the location of grainflow and grainfall on dune slipfaces the recent near surface wind direction short term wind can be identified results from the analysis of three dune fields on the floors of craters west of hellas basin show regional n nw se and ese wind directions in the three adjacent dune fields surface process and flow maps suggest a complex wind pattern the comparison of short term wind with dune constructing wind long term wind shows ne and ese winds may be persistent at least for the past thousands of years the results also show that the orientation of inferred wind direction on linear dunes is correlated with the crestlines which suggest that form flow interaction may take place the results of local wind flow documentation should improve martian surface wind modeling and advance our understanding of sand transport as well as the rates of sand mobility on both mars and earth

windy mars a dynamic planet as seen by the hirise camera 1 with a dynamic atmosphere and a large supply of particulate material the surface of mars is heavily influenced by wind driven or aeolian processes the high resolution imaging science experiment hirise camera on the mars reconnaissance orbiter mro provides a new view of martian geology with the ability to see decimeter size features current sand movement and evidence for recent bedform development is observed dunes and ripples generally exhibit complex surfaces down to the limits of resolution yardangs have diverse textures with some being massive at hirise scale others having horizontal and cross cutting layers of variable character and some exhibiting blocky and polygonal morphologies reticulate fine polygonal texture bedforms are ubiquitous in the thick mantle at the highest elevations

inverse maximum gross bedform normal transport 2 application to a dune field in ganges chasma mars and comparison with hirise repeat imagery and mrams abstract inverse maximum gross bedform normal transport imgbnt analysis has been applied to context camera ctx images of the largest dune field in ganges chasma on mars the dune field was selected for its position in a likely complex multi directional wind regime results indicate that four main winds are responsible for simultaneous construction of the dune field including along chasma winds from the ese winds blowing down a nearby re entrant from the ne winds blowing down the adjacent chasma wall from the nw and chasma floor winds from the sw each wind represents a transport vector that dominates dune morphology at its respective edge of the dune field such that the central axis of the dune field reflects the convergence of the three most prominent winds ese nw and sw the mars regional atmospheric modeling system mrams was run at twelve times throughout the martian year to provide context for the local wind patterns potential sand fluxes calculated from mrams output show that three major air flows from the ene e nne ne and nnw n converge near the location of the dune field these flows likely correspond to the ese ne and nw winds identified from imgbnt analysis respectively mrams output shows that the flows with major northerly components are produced by larger scale hadley return flow constructively combining with nighttime downslope winds the flow with a major easterly component is likely produced by equatorial easterly trade winds constructively combining with the diurnal tide and or local topography although the model correctly predicts the major elements of the local wind pattern some aspects are either over or underrepresented demonstrating the value of using aeolian morphological analysis to conclusively constrain the major sand moving winds on mars overlapping high resolution imaging experiment hirise images of barchanoid dunes at the northernmost edge of the dune field indicate that these dunes are currently migrating southward at 5 m mars year 2 6 m earth year the direction of migration is consistent with both mrams predictions in this location and the nw ne winds found from imgbnt analysis dune morphology suggests that sand in the northwestern part of the dune field is likely to be derived from the adjacent chasma wall to the north and northwest and sand in the southeastern part of the dune field was probably transported from farther east along the main chasma floor

gusev crater wind related features and processes observed by the mars exploration rover spirit 1 wind related features observed by the rover spirit in gusev crater mars include patches of soil on the surface some of which are organized into bed forms windblown grains include dust inferred to be 2 mm in diameter microscopic imager data show the sands and granules to be rounded and relatively spherical typical of grains transported long distances by the wind the interior of bed forms exposed by rover operations suggests the infiltration of dust among the grains indicating that these sands are not currently experiencing saltation orientations of 1520 features such as bed forms and ventifacts along spirit s traverse from the landing site the columbia memorial station to west spur in the columbia hills suggest primary formative winds from the north northwest which correlate with measurements of features seen in orbiter images and is consistent with afternoon winds predicted by atmospheric models a secondary wind from the southeast is also suggested which correlates with predictions for nighttime early morning winds wind abrasion is indicated by ventifacts in the form of facets and grooves cut into rocks the orientations of which also indicate prevailing winds from the north northwest orientations of many aeolian features in the west spur area however have more scatter than elsewhere along the traverse which is attributed to the influence of local topography on the patterns of wind active dust devils observed on the floor of gusev from the columbia hills demonstrate that dust is currently mobile sequential images of some dust devils show movement as rapid as 3 8 m s consistent with wind velocities predicted by atmospheric models for the afternoon when most of the dust devils were observed sands accumulated on the rover deck in the same period suggest that some sands in the columbia hills experience active saltation two toned rocks having a light band coating at their bases are considered to represent partial burial by soils and subsequent exposure while perched rocks could represent materials lowered onto other rocks by deflation of supporting soils measurements of the heights of the light bands and the perched rocks range from 1 cm to 27 cm indicating local deflation by as much as 27 cm

aeolian processes and dune morphology in gale crater abstract datasets at resolutions many times greater than previously available were used to study aeolian features within gale crater high resolution thermal inertia data allowed for detailed particle size estimation with the data sufficient to resolve dunefields a wide range of grain sizes have now been identified in the gale crater dunefields ranging from medium to very coarse sand high resolution imaging science experiment hirise and themis vis data allowed for detailed analysis of the dune morphology and slip faces which shows that the dunes have responded to topographic influences on prevailing wind directions under a present day wind regime this result was corroborated by a regional mesoscale model for the crater under dust storm conditions the central mound and smaller scale crater floor topography has altered the prevailing wind regime and dune patterns aeolian activity has thus played and continues to play an important role in shaping many of the present surface features of gale crater the arrival of a future lander mission such as the mars science laboratory would be able to sample these surface features directly and add a wealth of data to the understanding of gale crater

orbital change experiments with a mars general circulation model abstract we use a mars general circulation model to examine the effect of orbital changes on the planet s general circulation and climate system experiments are performed for obliquities ranging from 0 to 60 for two different longitudes of perihelion each experiment simulates a full mars year assuming a fixed atmospheric dust distribution and fixed amount of co 2 in the atmosphere cap system we find that global mean surface temperatures and pressures decline with increasing obliquity due to the increasing extent of the winter polar caps the seasonal co 2 cycle and intensity of the solstice circulation amplify considerably with increasing obliquity such that global dust storms are likely at both solstices the most significant feature of the high obliquity solstice circulations is the development of an intense low level jet associated with the return branch of the hadley circulation model surface stresses are used to map regions of preferred dust lifting which are defined in terms of an annual deflation potential for the present obliquity the model predicted regions of high deflation potential are in good agreement with cantor et al s 2001 j geophys res 106 23653 23688 observations which gives us some confidence in the model s ability to predict where lifting might occur when mars orbit parameters are different than they are today in general we find that the dust lifting potential increases sharply with obliquity and is greatest at times of high obliquity when perihelion coincides with northern summer solstice over an obliquity cycle the model global annual deflation potential ranges from several tenths of a millimeter at 0 obliquity to almost 15 mm at 60 obliquity much higher values are possible when the atmosphere is very dusty we find a strong correlation between the deflation potential and surface thermal inertia regions of high deflation potential correspond to regions of high thermal inertia high rock abundance and regions of low deflation potential correspond to regions of low thermal inertia high dust sand abundance furthermore while the regions of preferred lifting high deflation potential expand somewhat with increasing obliquity and dust loading the central parts of tharsis arabia and elysium show no tendency for significant lifting at any obliquity or longitude of perihelion these regions may therefore be very old and represent net long term sinks for atmospheric dust it is the topography of the planet through its influence on surface pressure and wind systems which ultimately determines where dust accumulates finally as was found by fenton and richardson 2001 j geophys res 106 32885 32909 we find no tendency for the development of east southeasterly winds at the pathfinder site for any of our orbital change experiments this suggests that the ancient wind regime discussed by greeley et al 2000 j geophys res 105 1829 1840 was produced by other factors such as polar wander

the influence of local topography for wind direction on mars two examples of dune fields in crater basins in this work we perform an analysis of large dark dunes within moreux crater and herschel crater on mars using high resolution imaging science experiment hirise and context camera ctx data sets these data allow us to conduct a detailed analysis of dune morphology and slip faces concluding that the studied dune fields are influenced by topographically controlled complex wind directions our morphological analysis reveals that inside moreux crater in particular the topographic setting dominates the wind flow direction leading to the development of a sand transport pathway encircling the central peak of the crater the dune fields in herschel crater are also affected by winds controlled by variable topography as suggested by the presence of complex dunes and dune fields our analysis indicate that the studied dune systems is not the result of paleo wind regimes furthermore we perform thermal inertia measurements using thermal emission spectrometer tes data which indicate that the studied dune fields consist of medium sand 250 500 mm in diameter

seasonal variability in winds in the north polar region of mars abstract surface features near mars polar regions are very active suggesting that they are among the most dynamic places on the planet much of that activity is driven by seasonal winds that strongly influence the distribution of water ice and other particulates morphologic features such as the spiral troughs chasma boreale and prominent circumpolar dune fields have experienced persistent winds for several myr therefore detailing the pattern of winds throughout the year is an important step to understanding what processes affect the martian surface in contemporary and past epochs in this study we provide polar focused mesoscale simulations from northern spring to summer to understand variability from the diurnal to the seasonal scales we find that there is a strong seasonality to the diurnal surface wind speeds driven primarily by the retreat of the seasonal co 2 until about summer solstice when the co 2 is gone the fastest winds are found when the co 2 cap boundary is on the slopes of the north polar layered deposits providing a strong thermal gradient that enhances the season long katabatic effect mid summer winds while not as fast as spring winds may play a role in dune migration for some dune fields late summer wind speeds pick up as the seasonal cap returns

martian aeolian features and deposits comparisons with general circulation model results the development of a general circulation model gcm of mars atmosphere allows questions to be addressed concerning the relationships between near surface winds and the distribution of wind related features and deposits predictions of wind surface stress as a function of season and dust optical depth are used to investigate the distribution and orientation of wind streaks yardangs and rock abundance on the surface the occurrence and orientation of bright streaks are well accounted for by the gcm results suggest that bright streaks form during southern hemisphere summer by hadley cell circulation in which dust is raised in the southern hemisphere carried northward at high altitudes then deposited in the wake of craters and other topographic obstacles by the descending hadley cell the reduction in the number of bright streaks southward from 30 n is interpreted to reflect the depletion of dust by near surface winds blowing to the south although the winds responsible for the formation of the dark streaks are not well reproduced in all areas by gcm simulations a band of high wind surface stresses in the southern subtropics corresponding to the latitude band where most of the dark streaks are found are predicted at the height of the dust storm season southern hemisphere summer yardang orientations do not match the gcm simulations for any season their orientation is attributed to either structural control in the rocks such as joint patterns or to a change in wind patterns from the time when the yardangs formed the global distribution of rocks on the surface is correlated well with predicted wind stress particularly during dust storm season the rocky areas are sites of strong winds suggesting that fine material is swept away by the wind leaving rocks and coarser material behind

assessing the martian surface distribution of aeolian sand using a mars general circulation model a sand transport model using white s 1979 sand flux equation and the mars general circulation model pollack et al 1990 was developed to understand the erosional sources transport pathways and depositional sinks of windblown sand on mars an initially uniform distribution of sand 4 mm over the entire surface is regionally transported based on wind stress saltation threshold and percentage of topographic trapping results are consistent with the observed polar and hellespontus dunes and christensen s 1986 modeled block size distribution but only for an extremely low saltation threshold 0 024 n m 2 low thresholds generally result in transport of sand sized particles originating in the northern mid latitudes to the north pole and transport from the northern lower latitudes to the southern hemisphere our results indicate that the polar dune fields could form in 50 000 years consistent with the active polar dunes and lack of longitudinal dunes observed on the surface of mars

columbia hills mars aeolian features seen from the ground and orbit 1 abundant wind related features occur along spirit s traverse into the columbia hills over the basaltic plains of gusev crater most of the windblown sands are probably derived from weathering of rocks within the crater and possibly from deposits associated with ma adim vallis windblown particles act as agents of abrasion forming ventifacts and are organized in places into various bed forms wind related features seen from orbit results from atmospheric models and considerations of topography suggest that the general wind patterns and transport pathways involve 1 winter nighttime winds that carry sediments from the mouth of ma adim vallis into the landing site area of spirit where they are mixed with locally derived sediments and 2 winter daytime winds that transport the sediments from the landing site southeast toward husband hill similar patterns occur in the summer but with weaker winds reversals of daytime flow out of gusev crater and nighttime wind flow into the crater can account for the symmetry of the bed forms and bimodal orientations of some ventifacts

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

aeolian dunes as ground truth for atmospheric modeling on mars 1 martian aeolian dunes preserve a record of atmosphere surface interaction on a variety of scales serving as ground truth for both global climate models gcms and mesoscale climate models such as the mars regional atmospheric modeling system mrams we hypothesize that the location of dune fields expressed globally by geographic distribution and locally by dune centroid azimuth dca may record the long term integration of atmospheric activity across a broad area preserving gcm scale atmospheric trends in contrast individual dune morphology as expressed in slipface orientation sf may be more sensitive to localized variations in circulation preserving topographically controlled mesoscale trends we test this hypothesis by comparing the geographic distribution dca and sf of dunes with output from the ames mars gcm and at a local study site with output from mrams when compared to the gcm 1 dunes generally lie adjacent to areas with strongest winds 2 dca agrees fairly well with gcm modeled wind directions in smooth floored craters and 3 sf does not agree well with gcm modeled wind directions when compared to mrams modeled winds at our study site 1 dca generally coincides with the part of the crater where modeled mean winds are weak and 2 sfs are consistent with some weak topographically influenced modeled winds we conclude that 1 geographic distribution may be valuable as ground truth for gcms 2 dca may be useful as ground truth for both gcm and mesoscale models and 3 sf may be useful as ground truth for mesoscale models

remote sensing and spatial analysis of aeolian sand dunes a review and outlook abstract for more than four decades remote sensing images have been used to document and understand the evolution of aeolian sand dunes early studies focused on mapping and classifying dunes recent advances in sensor technology and software have allowed investigators to move towards quantitative investigation of dune form evolution and pattern development these advances have taken place alongside progress in numerical models which are capable of simulating the multitude of dune patterns observed in nature the potential to integrate remote sensing rs spatial analysis sa and modeling to predict the future changes of real world dune systems is steadily becoming a reality here we present a comprehensive review of significant recent advances involving rs and sa our objective is to demonstrate the capacity of these technologies to provide new insight on three important research domains 1 dune activity 2 dune patterns and hierarchies and 3 extra terrestrial dunes we outline how several recent advances have capitalized on the improved spatial and spectral resolution of rs data the availability of topographic data and new sa methods and software we also discuss some of the key research challenges and opportunities in the application of rs and sa dune field including the integration of rs data with field based measurements of vegetation cover structure and aeolian transport rate in order to develop predictive models of dune field activity expanding the observational evidence of dune form evolution at temporal and spatial scales that can be used to validate and refine simulation models the development and application of objective and reproducible sa methods for characterizing dune field pattern and expanding efforts to quantify three dimensional topographic changes of dune fields in order to develop improved understanding of spatio temporal patterns of erosion and deposition overall our review indicates a progressive evolution in the way sand dunes are studied whereas traditional field studies of airflow and sand transport can clarify event based process form interactions investigators are realizing a synoptic perspective is required to address the response of dune systems to major forcings the integration and evolution of the technologies discussed in this review are likely to form a foundation for future advances in aeolian study

aeolian sediment transport pathways and aerodynamics at troughs on mars 1 interaction between wind regimes and topography can give rise to complex suites of aeolian landforms this paper considers aeolian sediment associated with troughs on mars and identifies a wider range of deposit types than has previously been documented these include wind streaks falling dunes lateral dunes barchan dunes linear dunes transverse ridges sand ramps climbing dunes sand streamers and sand patches the sediment incorporated into these deposits is supplied by wind streaks and ambient planitia sources as well as originating within the trough itself notably from the trough walls and floor there is also transmission of sediment between dunes the flow dynamics which account for the distribution of aeolian sediment have been modeled using two dimensional computational fluid dynamics the model predicts flow separation on the upwind side of the trough followed by reattachment and acceleration at the downwind margin the inferred patterns of sediment transport compare well with the distribution of aeolian forms model data indicate an increase of wind velocity by 30 at the downwind trough margin this suggests that the threshold wind speed necessary for sand mobilization on mars will be more frequently met in these inclined locations

aeolian processes in proctor crater on mars mesoscale modeling of dune forming winds 1 both atmospheric modeling and spacecraft imagery of mars are now of sufficient quality that the two can be used in conjunction to acquire an understanding of regional and local scale aeolian processes on mars we apply a mesoscale atmospheric model adapted for use on mars the mars mm5 to proctor crater a 150 km diameter crater in the southern highlands proctor crater contains numerous aeolian features that indicate wind direction including a large dark dune field with reversing transverse and star dunes containing three different slipface orientations small and older bright bedforms that are most likely transverse granule ripples and seasonally erased dust devil tracks results from model runs spanning a martian year with a horizontal grid spacing of 10 km predict winds aligned with two of the three dune slipfaces as well as spring and summer winds matching the dust devil track orientations the primary most prevalent dune slipface orientation corresponds to a fall and winter westerly wind created by geostrophic forces the tertiary dune slipface orientation is caused by spring and summer evening katabatic flows down the eastern rim of the crater influencing only the eastern portion of the crater floor the dunes are trapped in the crater because the tertiary winds enhanced by topography counter transport from the oppositely oriented primary winds which may have originally carried sand into the crater the dust devil tracks are caused by light spring and summer westerly winds during the early afternoon caused by planetary rotation the secondary dune slipface orientation is not predicted by model results from either the mars mm5 or the geophysical fluid dynamics laboratory mars general circulation model the reason for this is not clear and the wind circulation pattern that creates this dune slipface is not well constrained the mars mm5 model runs do not predict stresses above the saltation threshold for dune sand of the appropriate size and composition as with previous work the calculated wind velocities are too low which may be caused by too large of a grid spacing

albeluvisol development with time in loamy marine sediments of southern norway abstract this paper reports a study on soil development in loamy marine sediments on both sides of the oslofjord vestfold ostfold this region has been subject to steady glacio isostatic uplift during the whole holocene hence land surface age continuously increases from the coast inland several sea level curves based on radiocarbon datings enable estimation of land surface age for all locations clay illuviation starts in less than 1650 years e horizons become lighter with age but their lower boundary stays around 40 cm for more than 10 000 years albeluvic tongues develop between 4600 and 6200 years initially they form along intersections of cracks as preferential flow and leaching along the cracks continues the tongues increase in length and width progressively consuming the prisms between the cracks in the upper bt horizon the fe d fe t ratios weighted means of the upper meter show a clear linear increase with soil age and may be used for pedo dating i e for estimating the ages of non dated land surfaces covered with similar sediments in contrast the logarithmic decrease of base saturation and ph with rapid changes in the first time but only very slight changes between 2000 and 10 000 years makes these parameters unsuitable for pedo dating

present day aeolian activity in herschel crater mars abstract in this report we show evidence for ripple and dune migration in herschel crater on mars we estimate an average dune migration of 0 8 m and a minimum ripple migration of 1 1 m in a time span of 3 7 earth years these dunes and ripples are mainly shaped by prevailing winds coming from the north however we also report the presence of secondary winds which elongate the barchans horns such a complex wind scenario is likely caused by the influence of winds blowing off the western crater rim as suggested by the mars regional atmospheric modeling system mrams an atmospheric mesoscale model a multi directional wind regime at the local scale is also supported by the observed bimodal distribution of the ripple trends for the first time a survey integrating the assessment of dune and ripple migration is presented showing how dune topography can influence the migration patterns of ripples and how underlying topography appears to control the rates of dune migration

global map of eolian features on mars ten basic categories of eolian features on mars were identified from a survey of mariner 9 and viking orbiter images the ten features mapped are 1 light streaks including frost streaks 2 dark streaks 3 sand sheets or splotches 4 barchari dunes 5 transverse dunes 6 crescentic dunes 7 anomalous dunes 8 yardangs 9 wind grooves and 10 deflation pits the features were mapped in groups not as individual landforms and recorded according to their geographic positions and orientations on maps of 1 12 5 million or 1 25 million scale in the north polar region light and dark streaks indicate winds from the west and northwest frost streaks show northeast and northwest winds barchan dunes show southwest and west winds transverse dunes show east and west winds local erosional features show winds from the northwest or southeast and northeast or southwest in the middle and low northern latitudes streaks show northeast winds yardangs and deflation pits show mostly easterly and northeasterly winds in the low southern latitudes light streaks and dunes record northwest and northeast winds dark streaks record southeast winds in high southern latitudes most streaks and dunes record southeast and east winds in the south polar region light and frost streaks record southwest and northwest winds whereas dark streaks and transverse dunes show southeast winds the patterns recorded for ephemeral features conform to global conditions of strong southern spring and summer northern fall and winter wind circulation erosional features in bedrock indicate long term and perhaps ancient wind trends whereas depositional features may record relatively more recent winds wind directions indicated by yardangs pits and other erosional features seldom correspond to those shown by streaks these erosional features indicating winds of different directions than those that formed the streaks may have been carved when the effective regional winds on mars were different due to relative hemisphere insolation differences which are related to obliquity variations alternatively many yardangs and pits may be largely controlled by structure and carved along surface structural patterns or features that channeled both ancient and present day winds deflation pits in the mantled terrain may contain the best record of ancient wind trends these pits seem to have stratigraphically related orientations different stratigraphic units composing the mantle contain wind erosion pits that possibly record large scale wind direction changes because of long term changes in the obliquity of the mars

an investigation of martian northern high latitude and polar impact crater interiors atypical interior topographic features and cavity wall slopes abstract we examine martian northern high latitude and polar impact craters npics to better understand the north polar materials and polar processes we examine topographic characteristics for 346 npics and compare them to global fit data e g garvin et al 2003 boyce and garbeil 2007 as well as to a small set n 92 of southern high latitude and polar impact craters spics we find that the npic population above 57 n is significantly shallower than the global crater population this suggests that the npics 1 were initially shallow due to target properties of polar geologic units 2 were once deeper but have been infilled due to polar processes or 3 a combination of both indeed many of the npics exhibit considerable noncentral peak interior topographic features ifts which may be indicative of infilling processes the npic ifts also appear to display trends in their preferential orientation within the crater cavity some spics display similar interior features but do not show a clear preference in their orientation within the crater cavity in addition the npic population displays cavity wall slope trends that seem to indicate steepening of slopes with increasing crater diameter in comparison to the global slope trend garvin et al 2003 these trends suggest that the npics are unique in their geometry when compared to the global data set as well as with the spics further indicating that the north polar region may exhibit target properties and polar processes not seen in the south polar region or elsewhere on mars

active aeolian processes on mars a regional study in arabia and meridiani terrae 1 we present evidence of widespread aeolian activity in the arabia terra meridiani region mars where different kinds of aeolian modifications have been detected and classified passing from the regional to the local scale we describe one particular dune field in meridiani planum where two ripple populations are distinguished by means of different migration rates moreover a consistent change in the ripple pattern is accompanied by significant dune advancement between 0 4 1 meter in one martian year that is locally triggered by large avalanche features this suggests that dune advancement may be common throughout the martian tropics

earth aeolian wind streaks comparison to wind data from model and stations wind streak is a collective term for a variety of aeolian features that display distinctive albedo surface patterns wind streaks have been used to map near surface winds and to estimate atmospheric circulation patterns on mars and venus however because wind streaks have been studied mostly on mars and venus much of the knowledge regarding the mechanism and time frame of their formation and their relationship to the atmospheric circulation cannot be verified this study aims to validate previous studies results by a comparison of real and modeled wind data with wind streak orientations as measured from remote sensing images orientations of earth wind streaks were statistically correlated to resultant drift direction rdd values calculated from reanalysis and wind data from 621 weather stations the results showed good agreement between wind streak orientations and reanalysis rdd r 0 78 a moderate correlation was found between the wind streak orientations and the weather station data r 0 47 a similar trend was revealed on a regional scale when the analysis was performed by continent with r ranging from 0 641 in north america to 0 922 in antarctica at sites where wind streak orientations did not correspond to the rdds i e a difference of 45 seasonal and diurnal variations in the wind flow were found to be responsible for deviation from the global pattern the study thus confirms that earth wind streaks were formed by the present wind regime and they are indeed indicative of the long term prevailing wind direction on global and regional scales

present wind activity on mars relation to large latitudinally zoned sediment deposits the relation of present martian winds to large latitudinally zoned sediment deposits has been investigated using global wind streak data and mapping of large sand and dust deposits dune sand deposits occur primarily in three latitude belts north polar 74 85 degrees north low latitude 5 degrees north 20 degrees south and south polar 40 80 degrees south comparison with wind streak data shows the high latitude dunes to be in areas of seasonally reversing winds the present winds can form latitudinal dune belts from a variety of initial dune distributions including uniform distribution and a polar source the presence of dune sand within the polar layered deposits the erosional state of the deposits and the present surface wind flow away from the poles indicate that both polar dune concentrations have been derived from erosion of the layered deposits the low latitude dunes are topographically confined in canyons and craters they are probably subject to long term reversal of orientations with climate cycles

object based dune analysis automated dune mapping and pattern characterization for ganges chasma and gale crater mars abstract a method that enables the automated mapping and characterization of dune fields on mars is described using ctx image mosaics the introduced object based dune analysis obda technique produces an objective and reproducible mapping of dune morphologies over extensive areas the data set thus obtained integrates a large variety of data allowing a simple cross analysis of dune patterns spectral and morphometric information and mesoscale wind models two dune fields located in gale crater and ganges chasma were used to test and validate the methodology the segmentation of dune related morphologies is highly efficient reaching overall accuracies of 95 in addition we show that the automated segmentation of slipface traces is also possible with expected accuracies of 85 90 a qualitative and quantitative comparison of the final outputs with photointerpretations is performed and the precision of the directional characterization of the dune patterns is evaluated we demonstrate a good agreement between the obda outputs and the photointerpreted dune morphologies with local trend deviations below 45 for 80 95 of the mapped areas because the developed algorithm is tuned for the recognition of linear features from the imagery the slipfaces of small barchans can be preferentially overlooked owing to their small extent at the spatial resolution of the ctx mosaics dune types composed of longer linear morphologies are much better represented including correct mapping of secondary structures having proved the effectiveness and accuracy of the mapping procedure we discuss its future applications for the improvement of dune catalogs on mars

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

interpretation of the complex dune morphology on mars dune activity modelling and a terrestrial analogue in this work we analyze a dark erg on mars that could be considered a mega dune draa where secondary dunes of different morphology are superposed over a main crescent shaped bedform primary dune the presence of a complex multi directional wind regime is indicated as one of the main causes for the accumulation of a tall draa presenting an analogy to the great sand dunes in colorado in both cases main regional winds from the sw blow in opposition to winds from the ne which are enhanced by the topography such a complex wind regime leads to the development of star and reversing dunes and is accurately predicted by atmospheric models on a regional and local scale signs of activity in the form of grainflow scars are also noted over the slip faces of many dunes suggesting that easterly winds are actively shaping the study draa in the present day climatic setting the presence of this draa on mars suggests a complex interaction between regional and local topographically controlled flows and a consistent availability of sand the future study of an analogue terrestrial site such as the great sand dunes could be fundamental for understanding the evolution of similar martian dune fields copyright 2012 john wiley sons ltd

aeolian system sediment state theory and mojave desert kelso dune field example the sediment state of aeolian dune fields and sand seas at a basinal scale is defined by the separate components of sediment supply sediment availability and the transport capacity of the wind the sediment supply for aeolian systems is the sediment that contemporaneously or at some later point serves as the source material for the aeolian system numerous factors impact the susceptibility of grains on a surface to transport but these are cumulatively manifested by the actual transport rate which serves as a proxy for sediment availability transport capacity is the potential sediment transport rate of the wind because the three aspects of sediment state can be given as a volumetric rate they are directly comparable plotted simultaneously against time the generated curves define nine possible classes of sediment state sediment supply that is stored occurs because it is transport or availability limited or generated at a rate greater than the potential or actual transport rates respectively contemporaneous or lagged influx to an aeolian system may be limited by sediment availability but cannot exceed the transport capacity of the wind for the kelso dune field in the mojave desert of california a variety of stratigraphic and geomorphic evidence is used to approximate the sediment state of the system the sediment supply was generated during the latest pleistocene and earliest holocene during humid periods of enhanced discharge by the mojave river to form the lake mojave fan delta or terminal fan and has been calculated over time from the sedimentation rate and the frequency of floods estimation of transport capacity over time was based upon modern wind data with an allowance for greater winds during the pleistocene based upon climatic models sediment availability was approximated by calculation of a modern dune mobility index with variation over time based upon climatic inferences while quantifying the kelso or any natural system is subject to numerous uncertainties the sediment state approach reflects the temporal and spatial disjointed nature of accumulations at kelso as well as illuminating questions for future research

wind driven particle mobility on mars insights from mars exploration rover observations at el dorado and surroundings at gusev crater 1 the ripple field known as el dorado was a unique stop on spirit s traverse where dust raising active mafic sand ripples and larger inactive coarse grained ripples interact illuminating several long standing issues of martian dust mobility sand mobility and the origin of transverse aeolian ridges strong regional wind events endured by spirit caused perceptible migration of ripple crests in deposits sse of el dorado erasure of tracks in sandy areas and changes to dust mantling the site localized thermal vortices swept across el dorado leaving paths of reduced dust but without perceptibly damaging nearly cohesionless sandy ripple crests from orbit winds responsible for frequently raising clay sized dust into the atmosphere do not seem to significantly affect dunes composed of more easily entrained sand sized particles a long standing paradox this disparity between dust mobilization and sand mobilization on mars is due largely to two factors 1 dust occurs on the surface as fragile low density sand sized aggregates that are easily entrained and disrupted compared with clay sized air fall particles and 2 induration of regolith is pervasive light toned bed forms investigated at gusev are coarse grained ripples an interpretation we propose for many of the smallest linear light toned bed forms of uncertain origin seen in high resolution orbital images across mars on earth wind can organize bimodal or poorly sorted loose sediment into coarse grained ripples coarse grained ripples could be relatively common on mars because development of durable well sorted sediments analogous to terrestrial aeolian quartz sand deposits is restricted by the lack of free quartz and limited hydraulic sediment processing

planet wide sand motion on mars prior to mars reconnaissance orbiter data images of mars showed no direct evidence for dune and ripple motion this was consistent with climate models and lander measurements indicating that winds of sufficient intensity to mobilize sand were rare in the low density atmosphere we show that many sand ripples and dunes across mars exhibit movement of as much as a few meters per year demonstrating that martian sand migrates under current conditions in diverse areas of the planet most motion is probably driven by wind gusts that are not resolved in global circulation models a past climate with a thicker atmosphere is only required to move large ripples that contain coarse grains

constraints on mars recent equatorial wind regimes from layered deposits and comparison with general circulation model results aeolian modification has been a fundamental surface process on mars throughout the amazonian orientations of aeolian features such as bedforms and yardangs are controlled by the prevailing wind regime during the feature s formation therefore observation of recently formed bedform orientations provides a way to probe mars recent wind regime and constrain test general circulation models gcms we collect statistical distributions of transverse bedform and yardang azimuths at nine sites on mars and compare measured feature orientations to those predicted by using vector wind field output from the marswrf gcm we focus on layered deposits because their erodible nature makes them applicable to determination of mars modern wind regime our methods of mapping from the long term wind field to predicted feature orientations include consideration of wind stress thresholds for sand movement to occur sand flux equations and the direction of maximum gross bedform normal transport we find that all methods examined typically agree with each other to within 15 though there are some exceptions using high order wind stress weightings with multi directional annual wind fields generally use of higher wind stress thresholds produces improved matches to bedform orientations comparison of multiple yardang orientations to annually variable wind fields is accomplished by inspection of directional maxima in modelled wind vector frequency distributions yardangs match well to model predictions and sub populations in close proximity to each other are shown to match individual directional maxima in gcm output for a single site implying that topographic effects may produce very localised unidirectional wind fields unresolved by the gcm

mars global digital dune database and initial science results 1 a new mars global digital dune database mgd3 constructed using thermal emission imaging system themis infrared ir images provides a comprehensive and quantitative view of the geographic distribution of moderate to large size dune fields area 1 km2 that will help researchers to understand global climatic and sedimentary processes that have shaped the surface of mars mgd3 extends from 65 n to 65 s latitude and includes 550 dune fields covering 70 000 km2 with an estimated total volume of 3 600 km3 this area when combined with polar dune estimates suggests moderate to large size dune field coverage on mars may total 800 000 km2 6 times less than the total areal estimate of 5 000 000 km2 for terrestrial dunes where availability and quality of themis visible vis or mars orbiter camera narrow angle moc na images allow we classify dunes and include dune slipface measurements which are derived from gross dune morphology and represent the prevailing wind direction at the last time of significant dune modification for dunes located within craters the azimuth from crater centroid to dune field centroid referred to as dune centroid azimuth is calculated and can provide an accurate method for tracking dune migration within smooth floored craters these indicators of wind direction are compared to output from a general circulation model gcm dune centroid azimuth values generally correlate to regional wind patterns slipface orientations are less well correlated suggesting that local topographic effects may play a larger role in dune orientation than regional winds

aeolian slipface dynamics and grainflow morphologies on earth and mars abstract in 2015 an active dune field on mars was visited up close by the curiosity rover in gale crater providing the first high resolution ground images of fine scale windblown features not previously resolved from orbital based imagery for the first time these images allow for direct comparison with terrestrial aeolian dynamics and provide critical ground truth data to bridge the gap between model predictions and satellite observations the image data from the slipface on the namib dune within the bagnold dune field shows grainflow morphologies that are similar to dunes on earth quantitative estimates of flow thickness based on shadow length are presented for the grainflows on the namib dune slipface and compared to grainflow characteristics measured by terrestrial laser scans from the maspalomas dune field located in gran canaria spain using observations from maspalomas to support interpretations of martian slipface dynamics we discuss implications for the local wind regime style of grainflow seasonal activity and dune migration the presence of multiple large magnitude grainflows on the namib slipface suggests an active aeolian environment capable of delivering enough sediment to the slipface to initiate these flows and transport sediment to the bottom of the lee slope however the thinness of grainflows on the namib dune the formation of smaller grainflows directly below the dune brink and limited grainfall suggest a lower wind energy environment at least for the most recent slipface activity large actively migrating stoss ripples obliquely oriented to the dune crest regularly deposit sediment on to the upper slipface and may be a mechanism in which larger grainflow occur during seemingly low energy wind events this mechanism of sediment delivery may also explain the existence of a variety of slipface morphologies both young and old which are otherwise quickly erased on earth due to sediment redistribution and grainfall

the effect of unsteady winds on sediment transport on the stoss slope of a transverse dune silver peak nv usa rapid 10 s measurements of sediment transport and wind speed on the stoss slope of a transverse dune indicate that the majority of sand transported is associated with fluctuations in wind speed with a periodicity of 5 20 min duration increases in the sediment transport rate towards the dune crest are associated with a small degree of flow acceleration the increase in wind speed is sufficient however to greatly increase values of the intermittency index so that the duration of saltation is extended in crestal regions of the dune the pattern of sediment transport on the stoss slope and therefore the locus of areas of erosion and deposition change with the regional wind speed erosion of the crest occurs during wind speed events just above transport threshold whereas periods of higher magnitude winds result in deposition of sand upwind of the crest thereby increasing dune height although short term temporal and spatial relations between sand transport and wind speed on the stoss slope are well understood it is not clear how these relations affect dune morphology over longer periods of time

aeolian processes in proctor crater on mars sedimentary history as analyzed from multiple data sets 1 proctor crater is a 150 km diameter crater in noachis terra within the southern highlands of mars the analysis leading to the sedimentary history incorporates several data sets including imagery elevation composition and thermal inertia mostly from the mars global surveyor mission the resulting stratigraphy reveals that the sedimentary history of proctor crater has involved a complex interaction of accumulating and eroding sedimentation aeolian features spanning much of the history of the crater interior dominate its surface including large erosional pits stratified beds of aeolian sediment sand dunes erosional and depositional streaks dust devil tracks and small bright bed forms that are probably granule ripples long ago up to 450 m of layered sediment filled the crater basin now exposed in eroded pits on the crater floor these sediments are probably part of an ancient deposit of aeolian volcaniclastic material since then some quantity of this material has been eroded from the top layers of the strata small bright dune forms lie stratigraphically beneath the large dark dune field relative to the large dark dunes the bright bed forms are immobile although in places their orientations are clearly influenced by the presence of the larger dunes their prevalence in the crater and their lack of compositional and thermal distinctiveness relative to the crater floor suggests that these features were produced locally from the eroding basin fill dust devil tracks form during the spring and summer following a west southwesterly wind early in the spring the dust devils are largely restricted to dark patches of sand as the summer approaches dust devil tracks become more plentiful and spread to the rest of the crater floor indicating that the entire region acquires an annual deposit of dust that is revealed by seasonal dust devils the dark dunes contain few dust devil tracks suggesting that accumulated dust is swept away directly by saltation rather than by the passage of dust devils spectral deconvolution indicates that the dark dunes have infrared spectra consistent with basalt like materials the average thermal inertia calculated from thermal emission spectrometer bolometric temperatures is 277 17 j m 2 s 0 5 k 1 leading to an effective grain size of 740 170 mm which is consistent with coarse sand and within the range expected for martian sand the coarse sand that composes the large dune field may have originated from outside the crater saltating in from the southwest most of the transport pathway that delivered this sand to the dune field has since been eroded away or buried the sand was transported to the east center of the crater floor where beneath the present day dunes a 50 m high mound of sand has accumulated dune slip faces indicate a wind regime consisting of three opposing winds some of these wind directions are correlated with the orientations of dust devil tracks and bright bed forms the combination of a tall mound of sand and three opposing winds is consistent with a convergent wind regime which produces the large reversing transverse and star dunes that dominate the dune field the dark dunes have both active slip faces and seemingly inactive slip faces suggesting that the dunes vary spatially in their relative activity nevertheless the aeolian activity that has dominated the history of proctor crater still continues today index terms 5415 planetology solid surface planets erosion and weathering 5470 planetology solid surface planets surface materials and properties 5410 planetology solid surface planets

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

mars global digital dune database mgd3 north polar region mc 1 distribution applications and volume estimates the mars global digital dune database mgd3 now extends from 90 n to 65 s the recently released north polar portion mc 1 of mgd3 adds 844 000 km2 of moderate to large size dark dunes to the previously released equatorial portion mc 2 to mc 29 of the database the database available in gis and tabular format in usgs open file reports makes it possible to examine global dune distribution patterns and to compare dunes with other global data sets e g atmospheric models mgd3 can also be used by researchers to identify areas suitable for more focused studies the utility of mgd3 is demonstrated through three example applications first the uneven geographic distribution of the dunes is discussed and described second dune derived wind direction and its role as ground truth for atmospheric models is reviewed comparisons between dune derived winds and global and mesoscale atmospheric models suggest that local topography may have an important influence on dune forming winds third the methods used here to estimate north polar dune volume are presented and these methods and estimates 1130 km3 to 3250 km3 are compared with those of previous researchers 1158 km3 to 15 000 km3 in the near future mgd3 will be extended to include the south polar region published in 2011 this article is a us government work and is in the public domain in the usa

pervasive aeolian activity along rover curiosity s traverse in gale crater mars the nasa mars science laboratory msl rover curiosity has safely landed near a 35 km long dark dune field in gale crater on mars this dune field crosses the landing site from the northeast to the southwest and lies along curiosity s traverse to aeolis mons here we present the first evidence of recent aeolian activity in the form of ripple and dune migration and further estimate wind directions within the dune field through analysis of ripple and dune morphologies and the mars regional atmospheric modeling system mrams we measured a minimum ripple migration rate of 0 66 m per earth year and dune migration rate of 0 4 m per earth year in the southwest portion of the field a strongly bidirectional ripple crestline orientation nearly orthogonal dune slipfaces and linear seif or oblique dunes indicate a bidirectional wind regime with winds mainly coming from the ene and from the northwest however mrams results indicate primary winds from the ene our constraints on the wind regime provide the unique opportunity to use ground measurements from msl to test the accuracy of winds predicted from orbital data