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USGS2009

Currents in monterey submarine canyon

Flow fields of mean, subtidal, and tidal frequencies between 250 and 3300 m water depths in Monterey Submarine Canyon are examined using current measurements obtained in three yearlong field experiments. Spatial variations in flow fields are mainly controlled by the topography (shape and width) of the canyon. The mean currents flow upcanyon in the offshore reaches (>1000 m) and downcanyon in the shallow reaches (<800 m) of the canyon. Tidal currents, especially the semidiurnal components, are dominant and account for more than 90% of total energy. Pulses of strong currents near the canyon floor, which last several days at a time and have a magnitude as high as 60+ cm/s, are attributed to intense baroclinic processes occurring within the canyon. The V-shaped canyon walls and the near-critical slope of the canyon floor focus the baroclinic tides of semidiurnal and higher frequencies to the canyon bottom to produce the >100-m amplitude isotherm oscillations and associated high-speed rectilinear currents. The 15-day spring-neap cycle and a ???3-day??? band are the two prominent frequencies in subtidal flow field. Neither of them seems directly correlated with the spring-neap cycle of the sea level.

Journal of Geophysical Research C: Oceans↗
USGS2009

Generalized analytical model for benthic water flux forced by surface gravity waves

A generalized analytical model for benthic water flux forced by linear surface gravity waves over a series of layered hydrogeologic units is developed by adapting a previous solution for a hydrogeologic unit with an infinite thickness (Case I) to a unit with a finite thickness (Case II) and to a dual-unit system (Case III). The model compares favorably with laboratory observations. The amplitude of wave-forced benthic water flux is shown to be directly proportional to the amplitude of the wave, the permeability of the hydrogeologic unit, and the wave number and inversely proportional to the kinematic viscosity of water. A dimensionless amplitude parameter is introduced and shown to reach a maximum where the product of water depth and the wave number is 1.2. Submarine groundwater discharge (SGD) is a benthic water discharge flux to a marine water body. The Case I model estimates an 11.5-cm/d SGD forced by a wave with a 1 s period and 5-cm amplitude in water that is 0.5-m deep. As this wave propagates into a region with a 0.3-m-thick hydrogeologic unit, with a no-flow bottom boundary, the Case II model estimates a 9.7-cm/d wave-forced SGD. As this wave propagates into a region with a 0.2-m-thick hydrogeologic unit over an infinitely thick, more permeable unit, the Case III quasi-confined model estimates a 15.7-cm/d wave-forced SGD. The quasi-confined model has benthic constituent flux implications in coral reef, karst, and clastic regions. Waves may undermine tracer and seepage meter estimates of SGD at some locations. Copyright 2009 by the American Geophysical Union.

Journal of Geophysical Research C: Oceans↗
USGS2009

Probabilistic tsunami hazard assessment at Seaside, Oregon, for near-and far-field seismic sources

The first probabilistic tsunami flooding maps have been developed. The methodology, called probabilistic tsunami hazard assessment (PTHA), integrates tsunami inundation modeling with methods of probabilistic seismic hazard assessment (PSHA). Application of the methodology to Seaside, Oregon, has yielded estimates of the spatial distribution of 100- and 500-year maximum tsunami amplitudes, i.e., amplitudes with 1% and 0.2% annual probability of exceedance. The 100-year tsunami is generated most frequently by far-field sources in the Alaska-Aleutian Subduction Zone and is characterized by maximum amplitudes that do not exceed 4 m, with an inland extent of less than 500 m. In contrast, the 500-year tsunami is dominated by local sources in the Cascadia Subduction Zone and is characterized by maximum amplitudes in excess of 10 m and an inland extent of more than 1 km. The primary sources of uncertainty in these results include those associated with interevent time estimates, modeling of background sea level, and accounting for temporal changes in bathymetry and topography. Nonetheless, PTHA represents an important contribution to tsunami hazard assessment techniques; viewed in the broader context of risk analysis, PTHA provides a method for quantifying estimates of the likelihood and severity of the tsunami hazard, which can then be combined with vulnerability and exposure to yield estimates of tsunami risk. Copyright 2009 by the American Geophysical Union.

Journal of Geophysical Research C: Oceans↗
USGS2009

Climatic effects of 30 years of landscape change over the Greater Phoenix, Arizona, region: 1. Surface energy budget changes

This paper is part 1 of a two-part study that evaluates the climatic effects of recent landscape change for one of the nation's most rapidly expanding metropolitan complexes, the Greater Phoenix, Arizona, region. The region's landscape evolution over an approximate 30-year period since the early 1970s is documented on the basis of analyses of Landsat images and land use/land cover (LULC) data sets derived from aerial photography (1973) and Landsat (1992 and 2001). High-resolution, Regional Atmospheric Modeling System (RAMS), simulations (2-km grid spacing) are used in conjunction with consistently defined land cover data sets and associated biophysical parameters for the circa 1973, circa 1992, and circa 2001 time periods to quantify the impacts of intensive land use changes on the July surface temperatures and the surface radiation and energy budgets for the Greater Phoenix region. The main findings are as follows: since the early 1970s the region's landscape has been altered by a significant increase in urban/suburban land area, primarily at the expense of decreasing plots of irrigated agriculture and secondarily by the conversion of seminatural shrubland. Mean regional temperatures for the circa 2001 landscape were 0.12??C warmer than the circa 1973 landscape, with maximum temperature differences, located over regions of greatest urbanization, in excess of 1??C. The significant reduction in irrigated agriculture, for the circa 2001 relative to the circa 1973 landscape, resulted in dew point temperature decreases in excess of 1??C. The effect of distinct land use conversion themes (e.g., conversion from irrigated agriculture to urban land) was also examined to evaluate how the most important conversion themes have each contributed to the region's changing climate. The two urbanization themes studied (from an initial landscape of irrigated agriculture and seminatural shrubland) have the greatest positive effect on near-surface temperature, increasing maximum daily temperatures by 1??C. Overall, sensible heat flux differences between the circa 2001 and circa 1973 landscapes result in a 1 W m -2 increase in domain-wide sensible heating, and a similar order of magnitude decrease in latent heating, highlighting the importance of surface repartitioning in establishing near-surface temperature trends. In part 2 of this study, we address the role of the surface budget changes on the mesoscale dynamics/thermodynamics, in context of the large-scale environment. Copyright 2009 by the American Geophysical Union.

Journal of Geophysical Research D: Atmospheres↗
USGS2009

Overview of the magnetic properties experiments on the Mars Exploration Rovers

The Mars Exploration Rovers have accumulated airborne dust on different types of permanent magnets. Images of these magnets document the dynamics of dust capture and removal over time. The strongly magnetic subset of airborne dust appears dark brown to black in Panoramic Camera (Pancam) images, while the weakly magnetic one is bright red. Images returned by the Microscopic Imager reveal the formation of magnetic chains diagnostic of magnetite‐rich grains with substantial magnetization (>8 Am 2 kg −1 ). On the basis of Mössbauer spectra the dust contains magnetite, olivine, pyroxene, and nanophase oxides in varying proportions, depending on wind regime and landing site. The dust contains a larger amount of ferric iron (Fe 3+ /Fe tot ∼ 0.6) than rocks in the Gusev plains (∼0.1–0.2) or average Gusev soil (∼0.3). Alpha Particle X‐Ray Spectrometer data of the dust show that some of the iron in magnetite is substituted by titanium and chromium. The good correlation of the amount of calcium and sulfur in the dust may be caused by the presence of a calcium sulfate related phase. The overall mineralogical composition points to a basaltic origin of the airborne dust, although some alteration has taken place as indicated by the large degree of oxidation.

Journal of Geophysical Research E: Planets↗
USGS2008

Surface processes recorded by rocks and soils on Meridiani Planum, Mars: Microscopic Imager observations during Opportunity's first three extended missions

The Microscopic Imager (MI) on the Mars Exploration Rover Opportunity has returned images of Mars with higher resolution than any previous camera system, allowing detailed petrographic and sedimentological studies of the rocks and soils at the Meridiani Planum landing site. Designed to simulate a geologist's hand lens, the MI is mounted on Opportunity's instrument arm and can resolve objects 0.1 mm across or larger. This paper provides an overview of MI operations, data calibration, and analysis of MI data returned during the first 900 sols (Mars days) of the Opportunity landed mission. Analyses of Opportunity MI data have helped to resolve major questions about the origin of observed textures and features. These studies support eolian sediment transport, rather than impact surge processes, as the dominant depositional mechanism for Burns formation strata. MI stereo observations of a rock outcrop near the rim of Erebus Crater support the previous interpretation of similar sedimentary structures in Eagle Crater as being formed by surficial flow of liquid water. Well‐sorted spherules dominate ripple surfaces on the Meridiani plains, and the size of spherules between ripples decreases by about 1 mm from north to south along Opportunity's traverse between Endurance and Erebus craters.

Journal of Geophysical Research E: Planets↗
USGS2008

Wind-driven particle mobility on Mars: Insights from Mars Exploration Rover observations at "El Dorado" and surroundings at Gusev Crater

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. Copyright 2008 by the American Geophysical Union.

Journal of Geophysical Research E: Planets↗
USGS2008

Light-toned salty soils and co-existing Si-rich species discovered by the Mars Exploration Rover Spirit in Columbia Hills

Light-toned soils were exposed, through serendipitous excavations by Spirit Rover wheels, at eight locations in the Columbia Hills. Their occurrences were grouped into four types on the basis of geomorphic settings. At three major exposures, the light-toned soils are hydrous and sulfate-rich. The spatial distributions of distinct types of salty soils vary substantially: with centimeter-scaled heterogeneities at Paso Robles, Dead Sea, Shredded, and Champagne-Penny, a well-mixed nature for light-toned soils occurring near and at the summit of Husband Hill, and relatively homogeneous distributions in the two layers at the Tyrone site. Aeolian, fumarolic, and hydrothermal fluid processes are suggested to be responsible for the deposition, transportation, and accumulation of these light-toned soils. In addition, a change in Pancam spectra of Tyrone yellowish soils was observed after being exposed to current Martian surface conditions for 175 sols. This change is interpreted to be caused by the dehydration of ferric sulfates on the basis of laboratory simulations and suggests a relative humidity gradient beneath the surface. Si-rich nodules and soils were observed near the major exposures of S-rich soils. They possess a characteristic feature in Pancam visible near-infrared (Vis-NIR) spectra that may be diagnostic of hydrated species, and this spectral feature can be used to search for additional Si-rich species. The exposures of hydrated salty soils within various geomorphic settings imply the potential existence of hydrous minerals in similar settings over a much wider area. Hydrous sulfates represent one of the candidates that may contribute the high level of water equivalent hydrogen in equatorial regions detected by the Neutron Spectrometer on Mars Odyssey.

Journal of Geophysical Research↗
USGS2009

Reflectance spectroscopy of organic compounds: 1. Alkanes

Reflectance spectra of the organic compounds comprising the alkane series are presented from the ultraviolet to midinfrared, 0.35 to 15.5 /??m. Alkanes are hydrocarbon molecules containing only single carbon-carbon bonds, and are found naturally on the Earth and in the atmospheres of the giant planets and Saturn's moon, Titan. This paper presents the spectral properties of the alkanes as the first in a series of papers to build a spectral database of organic compounds for use in remote sensing studies. Applications range from mapping the environment on the Earth, to the search for organic molecules and life in the solar system and throughout the. universe. We show that the spectral reflectance properties of organic compounds are rich, with major diagnostic spectral features throughout the spectral range studied. Little to no spectral change was observed as a function of temperature and only small shifts and changes in the width of absorption bands were observed between liquids and solids, making remote detection of spectral properties throughout the solar system simpler. Some high molecular weight organic compounds contain single-bonded carbon chains and have spectra similar to alkanes even ' when they fall into other families. Small spectral differences are often present allowing discrimination among some compounds, further illustrating the need to catalog spectral properties for accurate remote sensing identification with spectroscopy.

Journal of Geophysical Research E: Planets↗
USGS2008

Degradation of Victoria crater, Mars

The ∼750 m diameter and ∼75 m deep Victoria crater in Meridiani Planum, Mars, is a degraded primary impact structure retaining a ∼5 m raised rim consisting of 1–2 m of uplifted rocks overlain by ∼3 m of ejecta at the rim crest. The rim is 120–220 m wide and is surrounded by a dark annulus reaching an average of 590 m beyond the raised rim. Comparison between observed morphology and that expected for pristine craters 500–750 m across indicates that the original, pristine crater was close to 600 m in diameter. Hence, the crater has been erosionally widened by ∼150 m and infilled by ∼50 m of sediments. Eolian processes are responsible for most crater modification, but lesser mass wasting or gully activity contributions cannot be ruled out. Erosion by prevailing winds is most significant along the exposed rim and upper walls and accounts for ∼50 m widening across a WNW–ESE diameter. The volume of material eroded from the crater walls and rim is ∼20% less than the volume of sediments partially filling the crater, indicating eolian infilling from sources outside the crater over time. The annulus formed when ∼1 m deflation of the ejecta created a lag of more resistant hematite spherules that trapped <10–20 cm of darker, regional basaltic sands. Greater relief along the rim enabled meters of erosion. Comparison between Victoria and regional craters leads to definition of a crater degradation sequence dominated by eolian erosion and infilling over time.

Journal of Geophysical Research E: Planets↗
USGS2008

Relative age of interior layered deposits in southwest Candor Chasma based on high-resolution structural mapping

High‐resolution topography generated from stereo HiRISE (High‐Resolution Imaging Science Experiment) imagery reveals the meter‐scale structure of interior layered deposits (ILD) in southwest Candor Chasma. This study seeks to determine the age of the local ILD relative to any normal faults that can be attributed to chasma formation. The study area is located near the contact of these ILD and the wall rock and is in an area where chasma‐forming normal faults have been proposed. We find that while normal faults are found in the study area, these faults are not sufficiently large nor appropriately located or oriented to accommodate the roughly northeast‐southwest extension that is required for normal faults that can be attributed to chasma formation. Additionally, bedding exposed in the local ILD generally dips toward the center of Candor Chasma, consistent with sediment deposition in a preexisting basin. Further, pit craters of Tithonia Catena, presumed to predate or be contemporaneous with the formation of west Candor Chasma, do not cut into the ILD within the study area. These independent lines of evidence support a postchasma age for the ILD exposed within the study area. Chasma‐related normal faults may exist within these ILD at depth but are not exposed at the surface. Approximately 2 km of conformable stratigraphy is exposed in the study area, and therefore at least several kilometers of the local ILD were deposited subsequent to any chasma‐related normal faulting that may have occurred in this part of Candor Chasma.

Journal of Geophysical Research E: Planets↗
USGS2008

Spirit Mars Rover Mission to the Columbia Hills, Gusev Crater: Mission overview and selected results from the Cumberland Ridge to Home Plate

This paper summarizes the Spirit rover operations in the Columbia Hills of Gusev Crater from sols 513 to 1476 and provides an overview of selected findings that focus on synergistic use of the Athena Payload and comparisons to orbital data. Results include discovery of outcrops (Voltaire) on Husband Hill that are interpreted to be altered impact melt deposits that incorporated local materials during emplacement. Evidence for extensive volcanic activity and aqueous alteration in the Inner Basin is also detailed, including discovery and characterization of accretionary lapilli and formation of sulfate, silica, and hematite‐rich deposits. Use of Spirit's data to understand the range of spectral signatures observed over the Columbia Hills by the Mars Reconnaissance Orbiter's Compact Reconnaissance Imaging Spectrometer (CRISM) hyperspectral imager (0.4–4 μ m) is summarized. We show that CRISM spectra are controlled by the proportion of ferric‐rich dust to ferrous‐bearing igneous minerals exposed in ripples and other wind‐blown deposits. The evidence for aqueous alteration derived from Spirit's data is associated with outcrops that are too small to be detected from orbital observations or with materials exposed from the shallow subsurface during rover activities. Although orbital observations show many other locations on Mars with evidence for minerals formed or altered in an aqueous environment, Spirit's data imply that the older crust of Mars has been altered even more extensively than evident from orbital data. This result greatly increases the potential that the surface or shallow subsurface was once a habitable regime.

Journal of Geophysical Research E: Planets↗
USGS2009

Spatial and temporal distributions of Martian north polar cold spots before, during, and after the global dust storm of 2001

In the 1970s, Mariner and Viking observed features in the Mars northern polar region that were a few hundred kilometers in diameter with 20 fj,m brightness temperatures as low as 130 K (considerably below C02 ice sublimation temperatures). Over the past decade, studies have shown that these areas (commonly called "cold spots") are usually due to emissivity effects of frost deposits and occasionally to active C02 snowstorms. Three Mars years of Mars Global Surveyor Thermal Emission Spectrometer data were used to observe autumn and wintertime cold spot activity within the polar regions. Many cold spots formed on or near scarps of the perennial cap, probably induced by adiabatic cooling due to orographic lifting. These topographically associated cold spots were often smaller than those that were not associated with topography. We determined that initial grain sizes within the cold spots were on the order of a few millimeters, assuming the snow was uncontaminated by dust or water ice. On average, the half-life of the cold spots was 5 Julian days. The Mars global dust storm in 2001 significantly affected cold spot activity in the north polar region. Though overall perennial cap cold spot activity seemed unaffected, the distribution of cold spots did change by a decrease in the number of topographically associated cold spots and an increase in those not associated with topography. We propose that the global dust storm affected the processes that form cold spots and discuss how the global dust storm may have affected these processes. ?? 2009 by the American Geophysical Union.

Journal of Geophysical Research E: Planets↗
USGS2009

Thorium abundances on the Aristarchus plateau: Insights into the composition of the Aristarchus pyroclastic glass deposits

Thorium (Th) data from the Lunar Prospector gamma ray spectrometer (LP‐GRS) are used to constrain the composition of lunar pyroclastic glass deposits on top of the Aristarchus plateau. Our goal is to use forward modeling of LP‐GRS Th data to measure the Th abundances on the plateau and then to determine if the elevated Th abundances on the plateau are associated with the pyroclastic deposits or with thorium‐rich ejecta from Aristarchus crater. We use a variety of remote sensing data to show that there is a large, homogenous portion of the pyroclastics on the plateau that has seen little or no contamination from the Th‐rich ejecta of Aristarchus crater. Our results show that the uncontaminated pyroclastic glasses on Aristarchus plateau have an average Th content of 6.7 ppm and ∼7 wt % TiO 2 . These Th and Ti values are consistent with Th‐rich, intermediate‐Ti yellow glasses from the lunar sample suite. On the basis of this information, we use petrologic equations and interelement correlations for the Moon to estimate the composition of the source region from which the Aristarchus glasses were derived. We find that the source region for the Aristarchus glasses contained high abundances of heat‐producing elements, which most likely served as a thermal driver for the prolonged volcanic activity in this region of the Moon.

Journal of Geophysical Research E: Planets↗
USGS2009

Observations of periglacial landforms in Utopia Planitia with the High Resolution Imaging Science Experiment (HiRISE)

The region of western Utopia Planitia (80-105 degreesE, 40-55 degrees N) displays several types of landforms similar to Earth periglacial features, including scallop-shaped depressions and networks of polygonal terrains. The scalloped depressions have been proposed to originate from thermokarstic processes such as sublimation and/or melting of near-surface ground ice. Using HiRISE imagery, we characterize these depressions and several associated, distinct polygon networks in unprecedented morphologic and topographic detail and investigate support for an ice-based degradation process. The scalloped depressions and interior polygons and ridges are found to evolve together, mainly influenced by sublimation, local proximity of ground ice to the surface, and obliquity variations.

Journal of Geophysical Research↗
USGS2009

Characterization of Mars' seasonal caps using neutron spectroscopy

Mars' seasonal caps are characterized during Mars years 26 and 27 (April 2002 to January 2006) using data acquired by the 2001 Mars Odyssey Neutron Spectrometer. Time-dependent maps of the column abundance of seasonal CO 2 surface ice poleward of 60?? latitude in both hemispheres are determined from spatially deconvolved, epithermal neutron counting data. Sources of systematic error are analyzed, including spatial blurring by the spectrometer's broad footprint and the seasonal variations in the abundance of noncondensable gas at high southern latitudes, which are found to be consistent with results reported by Sprague et al. (2004, 2007). Corrections for spatial blurring are found to be important during the recession, when the column abundance of seasonal CO 2 ice has the largest latitude gradient. The measured distribution and inventory of seasonal CO 2 ice is compared to simulations by a general circulation model (GCM) calibrated using Viking lander pressure data, cap edge functions determined by thermal emission spectroscopy, and other nuclear spectroscopy data sets. On the basis of the amount of CO 2 cycled through the caps during years 26 and 27, the gross polar energy balance has not changed significantly since Viking. The distribution of seasonal CO 2 ice is longitudinally asymmetric: in the north, deposition rates of CO 2 ice are elevated in Acidalia, which is exposed to katabatic winds from Chasma Borealis; in the south, CO 2 deposition is highest near the residual cap. During southern recession, CO 2 ice is present longer than calculated by the GCM, which has implications for the local polar energy balance. Copyright 2009 by the American Geophysical Union.

Journal of Geophysical Research E: Planets↗
USGS2009

Constraints on deep moonquake focal mechanisms through analyses of tidal stress

[1] A relationship between deep moonquake occurrence and tidal forcing is suggested by the monthly periodicities observed in the occurrence times of events recorded by the Apollo Passive Seismic Experiment. In addition, the typically large S wave to P wave arrival amplitude ratios observed on deep moonquake seismograms are indicative of shear failure. Tidal stress, induced in the lunar interior by the gravitational influence of the Earth, may influence moonquake activity. We investigate the relationship between tidal stress and deep moonquake occurrence by searching for a linear combination of the normal and shear components of tidal stress that best approximates a constant value when evaluated at the times of moonquakes from 39 different moonquake clusters. We perform a grid search at each cluster location, computing the stresses resolved onto a suite of possible failure planes, to obtain the best fitting fault orientation at each location. We find that while linear combinations of stresses (and in some cases stress rates) can fit moonquake occurrence at many clusters quite well; for other clusters, the fit is not strongly dependent on plane orientation. This suggests that deep moonquakes may occur in response to factors other than, or in addition to, tidal stress. Several of our inferences support the hypothesis that deep moonquakes might be related to transformational faulting, in which shear failure is induced by mineral phase changes at depth. The occurrence of this process would have important implications for the lunar interior. Copyright 2009 by the American Geophysical Union.

Journal of Geophysical Research E: Planets↗
USGS2009

THEMIS high-resolution digital terrain: Topographic and thermophysical mapping of Gusev Crater, Mars

We discuss a new technique to generate high-resolution digital terrain models (DTMs) and to quantitatively derive and map slope-corrected thermophysical properties such as albedo, thermal inertia, and surface temperatures. This investigation is a continuation of work started by Kirk et al. (2005), who empirically deconvolved Thermal Emission Imaging System (THEMIS) visible and thermal infrared data of this area, isolating topographic information that produced an accurate DTM. Surface temperatures change as a function of many variables such as slope, albedo, thermal inertia, time, season, and atmospheric opacity. We constrain each of these variables to construct a DTM and maps of slope-corrected albedo, slope- and albedo-corrected thermal inertia, and surface temperatures across the scene for any time of day or year and at any atmospheric opacity. DTMs greatly facilitate analyses of the Martian surface, and the MOLA global data set is not finely scaled enough (128 pixels per degree, ???0.5 km per pixel near the equator) to be combined with newer data sets (e.g., High Resolution Imaging Science Experiment, Context Camera, and Compact Reconnaissance Imaging Spectrometer for Mars at ???0.25, ???6, and ???20 m per pixel, respectively), so new techniques to derive high-resolution DTMs are always being explored. This paper discusses our technique of combining a set of THEMIS visible and thermal infrared observations such that albedo and thermal inertia variations within the scene are eliminated and only topographic variations remain. This enables us to produce a high-resolution DTM via photoclinometry techniques that are largely free of albedo-induced errors. With this DTM, THEMIS observations, and a subsurface thermal diffusion model, we generate slope-corrected maps of albedo, thermal inertia, and surface temperatures. In addition to greater accuracy, these products allow thermophysical properties to be directly compared with topography.

Journal of Geophysical Research E: Planets↗