Cross-polarization measurements and their relation to target surface properties.
Quantitative study of radar cross polarization factor D in order to obtain data on lunar surface roughness and dielectric properties
Krishen, K.↗
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Ion Implantatiion Improves Bearing-Surface Properties
Selected ions fired into rolling elements to increase resistance to rolling-contact fatique. Mask strips confine implantation to 105 degree arcs on cylindrical surfaces. Specimens kept cool by copper block through which refrigerant is circulated. Implanting nitrogen or titanium ions in metals improves resistance to fatigue, corrosion, and wear without altering bulk properties. Unlike such surface treatments as conventional nitriding, conventional carburizing, and coating, ion implantation is low-temperature process, requires no finishing operations, and produces highly-alloyed surface layer. Implantation process also helps conserve such strategic materials as chromium and cobalt by using them only where needed.
Misra, M. S.↗
Near-Real Time Satellite-Retrieved Cloud and Surface Properties for Weather and Aviation Safety Applications
Cloud properties determined from satellite imager radiances provide a valuable source of information for nowcasting and weather forecasting. In recent years, it has been shown that assimilation of cloud top temperature, optical depth, and total water path can increase the accuracies of weather analyses and forecasts. Aircraft icing conditions can be accurately diagnosed in near-‐real time (NRT) retrievals of cloud effective particle size, phase, and water path, providing valuable data for pilots. NRT retrievals of surface skin temperature can also be assimilated in numerical weather prediction models to provide more accurate representations of solar heating and longwave cooling at the surface, where convective initiation. These and other applications are being exploited more frequently as the value of NRT cloud data become recognized. At NASA Langley, cloud properties and surface skin temperature are being retrieved in near-‐real time globally from both geostationary (GEO) and low-‐earth orbiting (LEO) satellite imagers for weather model assimilation and nowcasting for hazards such as aircraft icing. Cloud data from GEO satellites over North America are disseminated through NCEP, while those data and global LEO and GEO retrievals are disseminated from a Langley website. This paper presents an overview of the various available datasets, provides examples of their application, and discusses the use of the various datasets downstream. Future challenges and areas of improvement are also presented.
Minnis, Patrick↗
Surface properties of asteroids - A synthesis of polarimetry, radiometry, and spectrophotometry
Surface compositions of 110 asteroids are analyzed using data obtained by polarimetry and visible and near-IR spectrophotometry. A comparison of albedos and diameters determined by polarimetry and radiometry indicates that a slight upward revision of the radiometric albedo scale is necessary. Reliable adopted albedos and diameters are presented for 56 objects, and rough diameters are obtained for 52 additional objects. More than 90% of the asteroids are shown to fall into two broad groups (C and S) which are compositionally similar to carbonaceous and stony meteorites, respectively. C-type asteroids are found to predominate in the asteroid belt, and the largest of these (Ceres, Pallas, Hygiea, Davida) may be metamorphosed. It is shown that Vesta may be the only differentiated asteroid remaining intact in the belt. The results support the conclusions that asteroids and meteorites have similar classes of mineral assemblages, but the distribution of asteroid types contrasts with the distribution of major meteorite types found on earth.
Chapman, C. R.↗
Surface properties and photometry of the Uranian satellites
Voyager photographic images and photopolarimetric experiment observations have been used to obtain the spectral geometric and Bond albedos, phase integrals, color-dependent phase coefficients, and integrated solar phase-curve parameters of the five Uranian satellites Miranda, Ariel, Umbriel, Titania, and Oberon. While the results obtained confirm those of Nelson et al. (1987) and Veverka et al. (1987) that these five largest Uranian satellites constitute a unique class of low-albedo and spectrally flat objects, attention is presently given to important differences among the five moons' surface physical properties.
Buratti, Bonnie↗
U-Surf: a global 1 km spatially continuous urban surface property dataset for kilometer-scale urban-resolving Earth system modeling
High-resolution urban climate modeling has faced substantial challenges due to the absence of a globally consistent, spatially continuous, and accurate dataset to represent the spatial heterogeneity of urban surfaces and their biophysical properties. This deficiency has long obstructed the development of urban-resolving Earth system models (ESMs) and ultra-high-resolution urban climate modeling, over large domains. Here, we present U-Surf, a first-of-its-kind 1 km resolution present-day (circa 2020) global continuous urban surface parameter dataset. Using the urban canopy model (UCM) in the Community Earth System Model as a base model for satisfying dataset requirements, U-Surf leverages the latest advances in remote sensing, machine learning, and cloud computing to provide the most relevant urban surface biophysical parameters, including radiative, morphological, and thermal properties, for UCMs at the facet and canopy level. Generated using a systematically unified workflow, U-Surf ensures internal consistency among key parameters, making it the first globally coherent urban canopy surface dataset. U-Surf significantly improves the representation of the urban land heterogeneity both within and across cities globally; provides essential, high-fidelity surface biophysical constraints to urban-resolving ESMs; enables detailed city-to-city comparisons across the globe; and supports next-generation kilometer-resolution Earth system modeling across scales. U-Surf parameters can be easily converted or adapted to various types of UCMs, such as those embedded in weather and regional climate models, as well as air quality models. The fundamental urban surface constraints provided by U-Surf can also be used as features for machine learning models and can have other broad-scale applications for socioeconomic, public health, and urban planning contexts. We expect U-Surf to advance the research frontier of urban system science, climate-sensitive urban design, and coupled human–Earth systems in the future. The dataset is publicly available at https://doi.org/10.5281/zenodo.11247598 (Cheng et al., 2024).
Cheng, Yifan [Univ. of Illinois at Urbana-Champaig↗
Modification of the Surface Properties of Polyimide Films using POSS Deposition and Oxygen Plasma Exposure
Topographically rich surfaces were generated by spray-coating organic solutions of a polyhedral oligomeric silsesquioxane, octakis (dimethylsilyloxy) silsesquioxane (POSS), on Kapton HN films and exposing them to radio frequency generated oxygen plasma. Changes in both surface chemistry and topography were observed. High-resolution scanning electron microscopy indicated substantial modification of the POSS-coated polyimide surface topographies as a result of oxygen plasma exposure. Water contact angles varied from 104 deg for unexposed POSS-coated surfaces to approximately 5 deg, for samples exposed for 5 h. Modulation of the dispersive and polar contributions to the surface energy was determined using van Oss Good Chaudhury theory.
Wohl, Christopher J.↗
Martian surface properties indicated by the opposition effect
Radiative transfer expressions are used to derive average surface particle single-scattering albedos, phase functions and porosities from a photometric comparison of Viking Orbiter opposition measurements of the Martian Arabia, Syrtis Major and Elysium Planitia regions with several generic features. The best functional fit to the data includes consideration of atmospheric scattering, two-particle populations and surface roughness. It is found that (1) the presence of high albedo, high porosity surface particles is ubiquitous, (2) opposition surge is absent in the Syrtis Major region, and (3) the Chryse areas possess the largest surface roughness.
Thorpe, T. E.↗
Martian Surface Properties: Inferences from Resolved Differences in Crater Geometries
Impact craters are a natural probe of planetary sub-surfaces, both from the excavated material and from crater geometries, which are sensitive to material properties of the target. One of the most intriguing aspects of Martian craters is the morphology of the ejecta blankets. All fresh and many older Martian craters larger than a few km are surrounded by ejecta blankets which appear fluidized, with morphologies believed to form by entrainment of liquid water. In addition to the ejecta morphology, quantitative information about the subsurface composition may be derived from geometrical measurements, e.g., rim uplift height and ejecta blanket volumes. In order to use craters to derive subsurface composition or test rampart morphology formation hypotheses, accurate measurements with quantified error estimates are required. We have developed and tested a toolkit for measurements of crater geometry using the MOLA altimetry data. Here, we present the results from geometry measurements on fresh craters in Lunae Planum and Utopia Planitia.
Valiant, G. J.↗
Multi-Satellite Estimates of Land-Surface Properties for Determination of Energy and Water Budgets
Using the WETNET database, existing methods for the estimation of surface wetness from SSM/I data have been assessed and further developed. A physical-statistical method for optimal estimation of daily surface heat flux and Bowen ratio on the mesoscale has been developed and tested. This method is based on observations of daytime planetary boundary layer (PBL) growth from operational ravansonde and daytime land-surface temperature amplitude from Geostationary Operational Environmental (GOES) satellites. The mesoscale patterns of these heat fluxes have been compared with an AVHRR-based vegetation index and surface wetness (separately estimated from SSM/I and in situ observations). Cases of the 1988 Midwest drought and a surface/atmosphere moisture gradient (dry-line) in the southern Plains were studied. The analyses revealed significant variations in sensible heat flux (S(sub 0), and Bowen ratio, B(sub 0)) associated with vegetation cover and antecedent precipitation. Relationships for surface heat flux (and Bowen ratio) from antecedent precipitation and vegetation index have been developed and compared to other findings. Results from this project are reported in the following reviewed literature.
Menzel, W. Paul↗
Surface properties of oils
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LUBRICATING OILS - FOAMING↗
Radar measurements of Martian topography and surface properties - The 1971 and 1973 oppositions
The Goldstone radar system was used at a wavelength of 12.6 cm to probe the Martian surface during the 1973 opposition. Measurements of range and reflected power were made at least weekly between July 12 and November 24. Surface cells isolated by the radar system were 8 km E-W by 110 km N-S. Altitudes were calculated from signal time delays measured relative to a triaxial ellipsoid and were combined with altitudes measured during the 1971 opposition. Contours of constant altitude were calculated at 200 m intervals between latitudes -14 and -22 deg. These contours are presented in conjunction with Mars charts derived from Mariner 9 television pictures. Reflected power was measured at angles of incidence between -5 and +5 deg. These measurements were combined with those obtained during the 1971 opposition.
Downs, G. S.↗
Surface properties of ancient cratered terrain in the northern hemisphere of Mars
Viking high resolution IR data is used in an examination of the hilly and cratered material of Scott and Carr (1978), supposed to be the oldest extensively exposed surface on Mars. Measured nighttime temperatures at 11 and 20 microns indicate inertia blocks, surrounded by lower thermal inertia soil. Geologic features crossed by the Viking data generally show no difference from the regional properties. Imaging data from within and around the Arabia low thermal inertia region indicate that subdued surface morphology is not always associated with low thermal inertias. The mantling of ancient northern hemisphere cratered terrain by fine grained material does not allow thermal measurements to be directly related to rock unit properties, but less mantling may be present in southern hemisphere locations of this material.
Zimbelman, J. R.↗
Surface properties of the Orgueil meteorite - Implications for the early history of solar system volatiles
The Kr and H2O adsorption properties of Orgueil were studied. Dehydration by stepwise calcination produced a tenfold change in its B.E.T. surface area, which increased to 120 and then fell to 40 square meters per gram. Water exchangeability was measured by water regain from lab air between calcination cycles. Dehydration at room temperature showed that Orgueil contained 6 per cent by weight of water adsorbed on free surfaces. These results are consistent with an identification of Orgueil as montmorillonite, although chemical data conflict with this. High D/H ratios in CI carbonaceous chondrites may result from D enrichment in OH- groups during equilibration of dispersed phyllosilicate dust with preplanetary nebula gas at temperatures much less than 0 C.
Fanale, F. P.↗
The surface properties of fluorinated polyimides exposed to VUV and atomic oxygen
The effect of atomic oxygen flux and VUV radiation alone and in combination on the surface of fluorinated polyimide films was studied using XPS spectroscopy. Exposure of fluorinated polyimides to VUV radiation alone caused no observable damage to the polymer surface, while an atomic oxygen flux resulted in substantial oxidation of the surface. On the other hand, exposure to VUV radiation and atomic oxygen in combination caused extensive oxidation of the polymer surface after only 2 minutes of exposure. The amount of oxidized carbon on the polymer surface indicated that there is aromatic ring opening oxidation. The changes in the O1s/C1s, N1s/C1s, and F1s/C1s ratios suggested that an ablative degradation process is highly favorable. A synergistic effect of VUV radiation in the presence of atomic oxygen is clearly evidenced from the XPS study. The atomic oxygen could be considered as the main factor in the degradation process of fluorinated polyimide films exposed to a low earth orbit environment.
Forsythe, John S.↗
Atmospheric and surface properties from spectral radiance observations in the 4.3-micron region
Atmospheric temperature profiles from terrestrial IR spectral radiances measured by balloon-borne grating spectrometer, discussing surface temperature variations
Chahine, M. T.↗
Martian topography and surface properties as seen by radar - The 1971 opposition.
Taking advantage of the favorable opposition of 1971, the Goldstone radar system, operating at 2388 MHz, was used to scan the Martian surface. Measurements of altitude and reflected power were taken approximately every 3 days. Each measurement represents an area 8 km E-W by 80 km N-S, the highest resolution attained to date. Altitude measurements obtained on different observing days were combined to produce altitude profiles for three complete rotations, each at different latitudes. Large-scale variations in altitudes cover a range of 14 km. Altitude changes of 5 in 30 km of longitude were observed. The altitude profiles show the heavy cratering of the surface, and several large craters (50-100 km) 1-2 km deep are easily seen.
Downs, G. S.↗
Preliminary Results of a New Type of Surface Property Measurement Ideal for a Future Mars Rover Mission
The success of the recent rover missions to Mars has stressed the importance of acquiring the maximum amount of geological information with the least amount of data possible. We have designed, tested and implemented special sensors mounted on a rover s wheel capable of detecting minute changes in surface topology thus eliminating the need for specially- made science platforms. These sensors, based on the previously designed, flight qualified Mars Environmental Compatibility Assessment (MECA) Electrometer, measure the static electricity (triboelectricity) generated between polymer materials and the Martian regolith during rover transverses. The sensors are capable of detecting physical changes in the soil that may not be detectable by other means, such as texture, size and moisture content. Although triboelectricity is a surface phenomenon, the weight of a rover will undoubtedly protrude the sensors below the dust covered layers, exposing underlying regolith whose properties may not be detectable through other means.
Buhler, C. R.↗