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  • Life and Medical Sciences  (1,044)
  • Analytical Chemistry and Spectroscopy  (901)
  • Inorganic Chemistry  (785)
  • ASTROPHYSICS  (709)
  • Organic Chemistry  (671)
  • EARTH RESOURCES AND REMOTE SENSING  (443)
  • 1995-1999
  • 1990-1994
  • 1985-1989  (4,553)
  • 1950-1954
  • 1985  (4,553)
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  • 1995-1999
  • 1990-1994
  • 1985-1989  (4,553)
  • 1950-1954
Year
  • 1
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    Vegetation canopy discrimination and biomass assessment using multipolarized airborne SAR (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Multipolarized airborne Synthetic Aperture Radar (SAR) data were acquired over a largely agricultural test site near Macomb, Illinois, in conjunction with the Shuttle Imaging Radar (SIR-B) experiment in October 1984. The NASA/JPL L-band SAR operating at 1.225 GHz made a series of daily overflights with azimuth view angles both parallel and orthogonal to those of SIR-B. The SAR data was digitally recorded in the quadpolarization configuration. An extensive set of ground measurements were obtained throughout the test site and include biophysical and soil measurements of approximately 400 agricultural fields. Preliminary evaluation of some of the airborne SAR imagery indicates a great potential for crop discrimination and assessment of canopy condition. False color composites constructed from the combination of three linear polarizations (HH, VV, and HV) were found to be clearly superior to any single polarization for purposes of crop classification. In addition, an image constructed using the HH return to modulate intensity and the phase difference between HH and VV returns to modulate chroma indicates a clear capability for assessment of canopy height and/or biomass. In particular, corn fields heavily damaged by infestations of corn borer are readily distinguished from noninfested fields.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA(JPL Aircraft SAR Workshop Proc.; p 67-75
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  • 2
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    Lithologic mapping in a sedimentary environment using multipolarization SAR images (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Multipolarization Synthetic Aperture Radar (SAR) data from the NASA/JPL aircraft SAR were used in conjunction with LANDSAT Thematic Mapper (TM), Thermal Infrared Multispectral Scanner (TIMS), and Airborne Imaging Spectrometer (AIS) data as part of a three-year research program to evaluate the utility of remote sensing measurements for analysis of sedimentary basins. The purpose of this research effort is to construct stratigraphic columns, map variations in the lithology, geometry, and structure of sedimentary rocks in the Wind River/Bighorn Basin area, Wyoming, and to integrate remote sensing data with conventional rain models of basin formation and evolution.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA(JPL Aircraft SAR Workshop Proc.; p 49-50
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  • 3
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    Comparative techniques used to evaluate Thematic Mapper data for land cover classification in Logan County, West Virginia (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Several digital data processing techniques were evaluated in an effort to identify and map active/abandoned, partially reclaimed, and fully revegetated surface mine areas in the central portion of Logan County. The TM data were first subjected to various enhancement procedures, including a linear contrast stretch, principal components and canonical analysis transformations. At the same time, four general procedures were followed to produce six classifications as a means of comparing the techniques involved. Preliminary results show that various feature extraction/data reduction techniques provide classification results equal or superior to the more straightforward unsupervised clustering technique. Analyst interaction time for labelling clusters is reduced using the canonical analysis and principal components procedures, though the canonical technique has clearly produced better results to date.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: LANDSAT-4 Sci. Characterization Early Results, Vol. 4; p 403-414
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  • 4
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    On the use of L-band multipolarization airborne SAR for surveys of crops, vineyards, and orchards in a California irrigated agricultural region (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The airborne L-band synthetic aperture radar (SAR) collected multipolarization calibrated image data over an irrigated agricultural test site near Fresno, CA, on March 6, 1984. The conclusions of the study are as follows: (1) the effects of incidence angle on the measured backscattering coefficients could be removed by using a correction factor equal to the secant of the angle raised to the 1.4 power, (2) for this scene and time of year, the various polarization channels were highly correlated such that the use of more than one polarization added little to the ability of the radar to discriminate vegetation type or condition; the exception was barley which separated from vineyards only when a combination of like and cross polarization data were used (polarization was very useful for corn identification in fall crops), (3) an excellent separation between herbaceous vegetation (alfalfa, barley, and oats) or bare fields and trees in orchards existed in brightness was well correlated to alfalfa height or biomass, especially for the HH polarization combination, (5) vineyards exhibited a narrow range of brightnesses with no systematic effects of type or number of stakes nor of number of wires in the trellises nor of the size of the vines, (6) within the orchard classes, areal biomass characterized by basal area differences caused radar image brightness differences for small to medium trees but not for medium to large trees.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA(JPL Aircraft SAR Workshop Proc.; p 63
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  • 5
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    Strategies for analyzing mixed pixels in remotely sensed imagery (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Two uncalibrated synthetic aperture radar (SAR) scenes from Death Valley, California, and two uncalibrated scenes from Owens Valley, California, were used to test a technique to identify and separate the primary factors associated with multipolarized radar image sets. Unique to the technique is the concept that varied types of radar polarization signatures are a result of the interaction of a few physical factors (e.g., roughness, volume scattering, and dielectric constant). Thus, the varied signatures observed in an image reflect the interaction between these factors. The objectives are to first separate the interaction of factors directly influencing the measurement and to attempt to identify these factors. Interpretation of the SAR image sets proceeds by testing models that hypothesize the cause and effect relations between those factors directly affecting the radar measurement and those features of interest to the interpreter. The results of our analysis indicated two consistent endmember types over all four image scenes. These types are defined by a high flat polarized signature near a level of 255 DN and a low level flat signature near 0 DN for all polarizations. Four other endmember types were also isolated. The spatial distribution of these endmember types indicates possible correspondence to surface volume scattering and changes in surface dielectric. However, the shapes of these endmember types were different from scene to scene.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: JPL NASA(JPL Aircraft SAR Workshop Proc.; p 47-48
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  • 6
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    Mapping diverse forest cover with multipolarization airborne radar (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Imaging radar backscatter in continuously forested areas contains information about the forest canopy; it also contains data about topography, landforms, and terrain texture. For purposes of radar image interpretation and geologic mapping researchers were interested in identifying and separating forest canopy effects from geologic or geomorphic effects on radar images. The objectives of this investigation was to evaluate forest canopy variables in multipolarization radar images under conditions where geologic and topographic variables are at a minimum. A subsidiary objective was to compare the discriminatory capabilities of the radar images with corresponding optical images of similar spatial resolution. It appears that the multipolarization images discriminate variation in tree density, but no evidence was found for discrimination between evergreen and deciduous forest types.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA(JPL Aircraft SAR Workshop Proc.; p 53-54
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  • 7
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    The effects of merging TM and A/C radar on wetland classification (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: While radar does not provide detailed begetation discrimination, it provide the means to separate areas of different moisture conditions. Thus, the use of LANDSAT Thematic Mapper (TM) in conjunction with the microwave data was attempted. If successful, information on shoreline cover, emergent wetland vegetation and extent, and submerged grassbeds would provide much needed data for planning and maintenance of wetlands. Originally, the goal was to determine the accuracy with which one could categorize various types of vegetation and land use within an inland wetland using LANDSAT TM data. First, a Level 1/2 supervised classification was performed. Following a more detailed ground trust survey, a Level 3 classification was done. Aircraft L-band radar data were received and the decision was made to merge the TM and L-band data and assess whether vegetation catagories within the wetland areas could be better defined. Preliminary results indicate vegetation delineation is improved for open agricultural areas and water, but other features are more confused.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: JPL NASA(JPL Aircraft SAR Workshop Proc.; p 37-38
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  • 8
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    The effect of vegetation type, microrelief, and incidence angle on radar backscatter (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The NASA/JPL Synthetic Aperture Radar (SAR) was flown over a 20 x 110 km test site in the Texas High Plains regions north of Lubbock during February/March 1984. The effect of incidence angle was investigated by comparing the pixel values of the calibrated and uncalibrated images. Ten-pixel-wide transects along the entire azimuth were averaged in each of the two scenes, and plotted against the calculated incidence angle of the center of each range increment. It is evident from the graphs that both the magnitudes and patterns exhibited by the corresponding transect means of the two images are highly dissimilar. For each of the cross-poles, the uncalibrated image displayed very distinct and systematic positive trends through the entire range of incidence angles. The two like-poles, however, exhibited relatively constant returns. In the calibrated image, the cross-poles exhibited a constant return, while the like-poles demonstrated a strong negative trend across the range of look-angles, as might be expected.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: JPL NASA(JPL Aircraft SAR Workshop Proc.; p 25-29
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  • 9
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    Neogene compressional deformation and possible thrust faulting in southwest Dominican Republic (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Analysis of regional and high resolution remote sensing data coupled with detailed field investigations indicates Neogene compressional deformation in the southwest Dominican Republic. Airborne synthetic aperture radar data and high resolution near infrared photography show folds in Tertiary sediments and possible thrust fault scarps implying NE to SW compression in the region. Large road cuts through the scarps allow study of otherwise poorly accessible, heavily vegetated karst terrain. Deformation increases toward scrap fronts where small bedding-plane thrust faults become more numerous. Analysis of mesoscopic faults with slickensides indicates compression oriented between N to S and E to W. The lowermost scarp has highly sheared fault breccia and undeformed frontal talus breccias implying it is the basal thrust into which the higher thrust faults sole. Thus, the scarps probably formed in a regional NE to SW compressional stress regime and are the toes of thrust sheets. Previous workers have suggested that these scarps are ancient shorelines. However, the gross morphology of the scarps differs substantially from well known erosional terraces on the north coast.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA(JPL Aircraft SAR Workshop Proc.; p 21
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  • 10
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    Modelling of vegetation volumes (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The purpose is to describe work that is being done to find theoretical models to describe radar backscatter from vegetation layers. The geometry of the problem is shown. The information that one would like to find through the application of the results of these models would include: the thickness of the layer; the absorption in the layer (i.e., density, moisture content, and biomass); the geometry of the scatterers (i.e., shape and orientation); how much of the received power is due to volume scattering only; and a way to enhance the ratio of scattering that has some interaction with the ground surface. The proposed ways to find this information are discussed.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA(JPL Aircraft SAR Workshop Proc.; p 77-79
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  • 11
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    Potential applications of multipolarization SAR for pine plantation biomass estimation (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: This study was conducted as a part of the research tasks under the Radar Land Cover Analysis Program. The Radar Land Cover Analysis objective is, through utilization of multisensor data, to gain a basic understanding of the measurements and data characteristics in the visible-IR-microwave regions of the electromagnetic spectrum associated with specific surface features and cover types. Since the results of analysis of data acquired by Shuttle Imaging Radar (SIR-A) and LANDSAT Thematic Mapper (TM) over the study area were reported (NSTL/ERL Report No. 228, December 1984), this study focused on the analysis and evaluation of the L-band multipolarization airborne SAR data acquired over a southeastern pine forest scene. The data acquisition mission was flown on September 8 and 9, 1983. The HH, HV polarizations and the VV, VH polarizations were used on the first and the second day, respectively. Due to instrumentation difficulties, the digital recorder recorded only the second day's data. Because of this, only the VV and VH polarization data were used in this analysis. However, the HH and HV polarization images were available for visual comparison. It appears that SAR digital numbers correlate with the index of green biomass.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: JPL NASA(JPL Aircraft SAR Workshop Proc.; p 59-61
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  • 12
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    Topographic mapping from interferometric synthetic aperture radar observations (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The production of high-resolution topographic maps derived from interferometric synthetic aperture radar observations of the Earth is reported. Topographic maps are typically determined from stereo-pair optical photographs. Vertical relief causes the same terrain to appear in a slightly different projection for differing look angles, and this shift in appearance is interpreted in terms of the height of the terrain. The radar interferometric approach is related to the stereo technique in that the terrain is viewed at two different angles; however, in this case, the angular separation of the antennas is extremely small, on the order of a milliradian or less, as compared to tens of degrees for the optical case. Thus, the geometrical distortion and subsequent rectification correction algorithms are much less severe in the reduction of interferometric data.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA(JPL Aircraft SAR Workshop Proc.; p 41-44
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  • 13
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    Interplanetary shock phenomena beyond 1 AU (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Attention is given to spatial dependences exhibited by spacecraft measurements obtained between 1 and 30 AU, together with temporal variations occurring between solar activity cycle maxima and minima. At 1-3 AU radial distances, shocks develop in association with the corotating solar wind streams characterizing solar minimum and accelerate solar wind evolution with distance while heating the solar wind and generating waves and turbulence. At solar maximum, shocks are observed more frequently at 1 AU but still in association with transient solar events; acceleration leading to energetic storm particles is observed both within and beyond 1 AU. The superimposed effect of large numbers of intense shocks may be responsible for the solar cycle modulation of galactic cosmic rays.
    Keywords: ASTROPHYSICS
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  • 14
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    Nucleus studies of Comet Halley (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Early results from, and research initiatives warranted by, the earth-based observations of Halley's near-nucleus and related phenomena are reviewed. Where appropriate, this information is combined with spacecraft data obtained by the various flight projects. The basic objective is to gain a greater insight into the nature of the comet's nucleus and its environment.
    Keywords: ASTROPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 5; 12, 1; 307-316
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  • 15
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    Preliminary results of the Giotto radio science experiment (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Doppler and ranging measurements using the radio signal of the Giotto spacecraft were taken before, during, and after the encounter with Comet Halley on Mar. 13, 14, 1986. The spacecraft velocity was found to decrease by a total of 23.3 cm/s due to impacting gas and (primarily) dust in the cometary atmosphere. A preliminary dust production rate of 1000 kg/s is found to be consistent with this deceleration. Power spectra of the carrier phase fluctuations reveal an increase in level and a flattening of the spectrum just prior to encounter, presumably associated with the enhanced dust impact rate. Finally, simulated Doppler time profiles are computed using the radial dependence of plasma density observed by the Giotto in situ investigations. It is shown that the cometary electron content profile would have been clearly seen if a dual-frequency downlink radio configuration had been available at encounter.
    Keywords: ASTROPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 5; 12, 1
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  • 16
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    A preliminary look at the dust in Comet Halley (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Highlights of infrared observations of the dust are discussed and compared with first results from the space probes. An emission feature was detected at 3.4 microns; the 10 and 20 micron silicate features were well-observed; and far-infrared data out to 160 micron were obtained. Organic material seems to be abundant in grains and may explain the 3.4 micron emission. Calculations are presented for one example of organic material. A component of the grains may volatize at temperatures around 300 K.
    Keywords: ASTROPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 5; 12, 1; 325-334
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  • 17
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    Cometary kilometric radio waves and plasma waves correlated with ion pick-up effect at Comet Halley (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Bow-shock movements at Comet Halley are inferred from the discrete spectra of the cometary kilometric radiation (30-195 kHz); the observed emissions can be interpreted as being generated and propagating from the moving shock. The shock motion is possibly associated with the time variation of the solar wind and cometary outgassing. It is concluded that these plasma wave phenomena are manifestations of ion pick-up processes, which occur even in a remote region 7 million to 10 million km from the cometary nucleus.
    Keywords: ASTROPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 5; 12, 1; 83-88
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  • 18
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    High spectral resolution remote sensing of the earth (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Early results of a major advance in remote sensing called imaging spectrometry (IS), the simultaneous acquisition of images in many narrow contiguous spectral bands throughout the visible and solar-reflected infrared portions of the spectrum, are discussed. The motivation for IS is reviewed, and the performance of IS is examined, describing prototype sensors. The analysis of IS data is addressed, including the problem of visual interaction with hyperspectral images and their statistical properties, and the effect of data dimensionality on multispectral scene classification. A test of the capability of imaging spectrometry to identify minerals is reported.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Sensors (ISSN 0746-9462); NASA-sup
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  • 19
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    CNO isotopes in red giant stars (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Observational data on CNO abundance ratios in red giants and the interstellar medium (ISM) are analyzed for the implications for the production and distribution of CNO nuclides. The data included isotope abundance measurements for the atmospheres and recent ejecta of cool giants, e.g., carbon stars, S-type stars, red supergiants and oxygen-rich giants beginning an ascent of the giant branch. The contribution of intermediate-mass stars to galactic nuclear evolution is discussed after comparing red giant abundances with ISM abundances, particularly the isotopes O-16, -17 and -18. The O-12/O-18 ratios of red giants are distinctly different from those in interstellar molecular clouds. The CNO values also vary widely from the values found in the solar system.
    Keywords: ASTROPHYSICS
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  • 20
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    CNO abundances in novae ejecta (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Isotope production, particularly CNO, which are enhanced in novae events and the interstellar medium (ISM) by novae are discussed in terms of emission-line data taken a few weeks after novae events. The emission-line abundances emerge only after the fading of absorption spectrum, and are also detectable in thin shells which sometimes, though rarely, form after novae. CNO abundances in these shells are equivalent to those observed in fading novae, with CNO/H ratios being 100 times solar values. Possible heavy element production pathways in the events and their shrinking are discussed, along with observation techniques for detecting CNO isotopes through absorption data on atomic transitions in novae ejecta and the ISM.
    Keywords: ASTROPHYSICS
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  • 21
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    Close-range photogrammetry with video cameras (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Examples of photogrammetric measurements made with video cameras uncorrected for electronic and optical lens distortions are presented. The measurement and correction of electronic distortions of video cameras using both bilinear and polynomial interpolation are discussed. Examples showing the relative stability of electronic distortions over long periods of time are presented. Having corrected for electronic distortion, the data are further corrected for lens distortion using the plumb line method. Examples of close-range photogrammetric data taken with video cameras corrected for both electronic and optical lens distortion are presented.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 22
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    An analysis of IRAS' solar system dust bands (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Measurements of longitudinal variations in the brightness and in the latitude of the solar system dust bands recently discovered by IRAS will determine the orbital elements of the particles involved and may discriminate between cometary and asteroidal models of the origin of these bands. The expected variations for bands of dust particles with common orbital elements and small eccentricity and inclination are calculated as functions of semimajor axis.
    Keywords: ASTROPHYSICS
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  • 23
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    Mass input into and output from the meteoritic complex (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The consequences which arise from the mutual collisions occurring between interplanetary meteoroids, the Poynting-Robertson (PR) effect and the radiation pressure ejection of small meteoroids are examined. The size distribution and flux of micrometeoroids at 1 AU are derived and the dependence of spatial density on distance from the sun is established. The following conclusions are made: (1) the lifetimes of meteoroids with masses approximately greater than 0.00001 g are dominated by catastrophic collisions; (2) after bering crushed by collisions, 70 to 85 percent of this mass will be in the form of zodiacal light particles (with masses in the range of 10 to the -10th g to 10 to the -5th g) which will in part be transported by the PR effect towards the sun where they will evaporate; (3) the 15 to 30 percent of the collisional fragments which have masses approximately less than 10 to the -10th g will, for the most part, be injected into hyperbolic orbits by radiation pressure.
    Keywords: ASTROPHYSICS
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  • 24
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    Selection effects against small comets (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Everhart's (1967) formulation is used to determine the correlation between the probability of discovering a comet and the size of its nuclear radius. The analysis is concentrated on comets that are not more than two or three hundred meters in diameter; hence, heliocentric variations in cometary brightness can be neglected. The effect of cometary physical decay is also considered, and a strong observational bias against the detection of small active comets is found. The following three factors are involved: (1) small comets must pass closer to the earth than large comets in order to be detected, (2) the resulting higher angular velocity for nearby comets leads to a decrease in the time available to discover a small comet, and (3) small comets physically decay and vanish faster than do large comets.
    Keywords: ASTROPHYSICS
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  • 25
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    IRAS observations of the interplanetary dust emission (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The Infrared Astronomical Satellite (IRAS) has completed a sensitive, highly redundant survey of the full sky in four broad photometric bands at 12, 25, 60, and 100 micrometers wavelength. The survey measured interplanetary dust emission over elongation angle ranging from 60 to 120 degrees. Bright emission from the main cloud is consistent with optically thin blackbody emission. The grains are evidently quite black, with an 'apparent albedo' of about 0.07. The data show clear evidence for deviation of the dust symmetry surface from the ecliptic plane. Surprising bands of emission were discovered near the ecliptic plane and about ten degrees on either side of it. The heliocentric distance of this material, suggested to be asteroidal in origin, is inferred to be about 2.5 AU from both color temperature and parallax measurements.
    Keywords: ASTROPHYSICS
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  • 26
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    Large and small scale structures of molecular clouds in the Taurus Perseus complex (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The gaseous components studied in H I and OH absorption against the extragalactic radiosources 3C123 and 3C111 are found to be the low-density edges of condensations of a few 100 solar masses. The densest part of one of these condensations has a structure similar to that found in other dark clouds: it is fragmented into several cores of a few solar masses, with an orbital velocity dispersion of about 2 km/s. In turn, the extended low-density layer, optically thick in CO (2-1), is not a common feature. It depends on the ambient UV field, but the dust temperature in the core may control its existence. Even more critically; it is found that the lower is the dust temperature, the less massive is the core and the more extended is the envelope around it, for a given total mass in a given external pressure.
    Keywords: ASTROPHYSICS
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  • 27
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    Cepheid variables as extra-galactic distance indicators (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The role of Cepheid variables in establishing the inner distance scale to nearby galaxies is discussed. Emphasis is placed on the necessity for broad wavelength coverage in attempting to account for metallicity differences and reddening internal to the parent galaxies. In addition linear detectors are essential in minimizing the effects of any unresolved background contribution to the photometry. Recent infrared observations of Cepheids in Local Group galaxies are surveyed and all published data on extra galactic Cepheids are presented for convenient access.
    Keywords: ASTROPHYSICS
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    The 50 millisecond pulsar in the Large Magellanic Cloud and the X-ray pulse emission mechanism (1985)
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    Publication Date: 2011-08-19
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    Interstellar clouds - From a dynamical perspective on their chemistry (1985)
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    Publication Date: 2011-08-19
    Description: The possibility is examined that in the course of its dynamical evolution, a single mass of interstellar gas would exhibit properties of diffuse clouds, dense clouds and finally also of clouds perturbed by shocks or intense UV or X-ray radiation generated by a star of its own creation. This concept provides a common thread through the bewildering diversity of physical and chemical compositional properties shown by interstellar clouds. From this perspective, instead of being static objects, interstellar clouds are possibly incessantly evolving from initially diffuse to later dense state and then to star formation which ultimately restructures or disperses the remaining cloud material to begin the whole evolutionary process once again. Based on a simplified study of interstellar chemistry from a dynamical perspective, the ideas are presented as an heuristic: to encourage thought on the future direction of molecular astrophysics and the need to consider the chemical behavior of interstellar clouds in conjunction with, rather than in isolation from, their dynamical behavior. A physical basis must be sought for the semiempirical temperature formula which has been given a critical role in the collapse of diffuse clouds. Self-shielding effects in the chemistry of CO were neglected and this drawback should be removed; the ability of the model to explain the fractional abundances of more complex molecules, such as cyanopolyynes, should be examined.
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    Cometary comae (1985)
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    Publication Date: 2011-08-19
    Description: The basis of our knowledge about the structure and composition of a comet nucleus is examined. Such knowledge is inferred from observations of the cometary atmosphere (coma). However, photodissociation, photoionization, and chemistry destroy the mother molecules evaporating from the nucleus. To extract the primary information, the chemical kinetics and the physics of the coma are modeled with a computer and the results are compared with coma observations. The physics and chemistry for a dust free coma are described taking into account energy balance, multi-fluid flow for fast atomic and molecular hydrogen and the bulk fluid, and the transition from a collision dominated inner region to the free molecular flow outer region. Special attention is paid to the molecular data requirements for the current modeld and for extended models which will include solar wind interaction and dust. Such models are an important tool in support of the Giotto mission to Halley's comet, in the analysis and interpretation of coma observations, and in the understanding of the earliest history of the solar system.
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    Assisting extrasolar planetary detection through the determination of stellar space orientations (1985)
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    Publication Date: 2011-08-19
    Description: Various methods outlined for indirect planetary detection would greatly benefit (in some cases require) the determination of the planetary orbital plane, which is theoretically equivalent to the stellar equatorial plane. Determining the stellar space orientation, therefore, would greatly benefit extrasolar planetary detection. Stellar rotation periods determined from short-term variations in Ca II H and K sunspot emission are utilized together with both stellar radii measurements and Doppler-broadened spectral line profiles to get the stellar inclination to the line of sight. The clocklike on-the-plane-of-the-sky component determination utilizes the concentration of sunspot-associated plage areas at central stellar latitudes when viewed in Ca II H or K emission. One can perform Ca II H and K emission speckle interferometry to measure the clocklike angle of this stellar Ca II H and K emission band, modeling it as an elliptical intensity distribution. Both components should be determinable to within 10 deg for at least the resolvable fifth magnitude stars.
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    Problems with interpreting the radio emission from hot stars (1985)
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    Publication Date: 2011-08-19
    Description: Problems in hot star radio emission interpretation due to radio flux source and other modeling assumptions are examined. An upper limit constraint on the value of the mass loss rate divided by the constant wind velocity is imposed by assuming that the outflow is due to bremsstrahlung in a spherically symmetric wind with the stationary photosphere visible at 4500 A, and by the need for it to be less than the luminosity divided by c. The constraints are satisfied for the deduced values for OB supergiants, and to some extent for early 0 stars, but not for Wolf-Rayet stars, due to mass loss rates excessive by a factor of 10. It is suggested that the problem can be solved by postulating that part of the radio flux from Wolf-Rayet stars is due to processes in a low-density magnetized plasma.
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    Dynamical evolution of the Oort cloud (1985)
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    Publication Date: 2011-08-19
    Description: New studies of the dynamical evolution of cometary orbits in the Oort cloud are made using a revised version of Weissman's (1982) Monte Carlo simulation model, which more accurately mimics the perturbation of comets by the giant planets. It is shown that perturbations by Saturn and Jupiter provide a substantial barrier to the diffusion of cometary perihelia into the inner solar system. Perturbations by Uranus and Neptune are rarely great enough to remove comets from the Oort cloud, but do serve to scatter the comets in the cloud in initial energy. The new model gives a population of 1.8 to 2.1 x 10 to the 12th comets for the present-day Oort cloud, and a mass of 7 to 8 earth masses. Perturbation of the Oort cloud by giant molecular clouds in the galaxy is discussed, as is evidence for a massive 'inner Oort cloud' internal to the observed one. The possibility of an unseen solar companion orbiting in the Oort cloud and causing periodic comet showers is shown to be dynamically plausible but unlikely, based on the observed cratering rate on the earth and moon.
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    Agricultural applications for thermal infrared multispectral scanner data (1985)
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    Publication Date: 2011-08-19
    Description: The use of the Thermal Infrared Multispectral Scanner (TIMS) data in agricultural landscapes is discussed. The TIMS allows for narrow-band analysis in the 8.2-11.6 micron range at spatial resolutions down to 5 meters in cell size. A coastal plain region in SE Alabama was studied using the TIMS. The crop/plant vigor, canopy density, and thermal response changes for soils obtained from thermal imagery are examined. The application of TIMS data to hydrologic and topographic issues, inventory and conservation monitoring, and the enhancement and extraction of cartographic features is described.
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    Preliminary science results from the Shuttle Imaging Radar-B (1985)
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    Publication Date: 2011-08-19
    Description: Preliminary results of analyzing digital radar imagery data obtained by the SIR-B aboard the Space Shuttle Challenger STS 41-G are presented. The data cover 5 million square kilometers of the earth surface between 57 deg north and south latitudes. Radar imagery of the same target at different incidence angles was used to classify surfaces by their backscatter response as a function of incidence angle. The SIR-B proved to be useful for collecting multiple incidence angle data sets over a broad range of targets, providing information in the areas of geology, archeology, forestry, agriculture, oceanography, geography, and hydrology. The analysis is also used to optimize radar parameters such as look angle for future missions.
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    A new emission feature in IRAS spectra and the polycyclic aromatic hydrocarbon spectrum (1985)
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    Publication Date: 2011-08-19
    Description: IRAS spectra of those sources which show strong 7.7 and 11.3 micron emission features also show a plateau of emission extending from 11.3 to about 13.0 microns. Like the 11.3 micron feature, this new feature is attributed to the CH out-of-plane bending mode in polycyclic aromatic hydrocarbons (PAHs). Its discovery reinforces the identification of the 'unidentified infrared emission features' as emission from PAHs. The wavelength of this new feature suggests that interstellar PAHs are not as partially hydrogenated as hitherto thought. It also constrains their molecular structure.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 299; L93-L97
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    Near-infrared mapping of ARP 299 (IC 694-NGC 3690) - Colliding galaxies unveiled (1985)
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    Publication Date: 2011-08-19
    Description: Near-infrared maps and multicolor photometry of the interacting galaxies IC 694 and NGC 3690 which form Arp 299 (= Markarian 171) are presented. These data reveal for the first time the distribution of nuclei and old red stars in a cataclysmically interacting system. The nuclei are considerably offset from the visual centroids of the galaxies but not from the mass centroids. The near-infrared colors of the most active regions are strongly affected by extinction, emission form hot dust, and bremsstrahlung. Near-infrared emission is also identified with secondary regions of star formation, probably resulting from the galaxies' interaction.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 299; 896-904
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    Forest discrimination with multipolarization imaging radar (1985)
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    Publication Date: 2011-08-19
    Description: The use of radar polarization diversity for discriminating forest canopy variables on airborne synthetic-aperture radar (SAR) images is evaluated. SAR images were acquired at L-Band (24.6 cm) simultaneously in four linear polarization states (HH, HV, VH, and VV) in South Carolina on March 1, 1984. In order to relate the polarization signatures to biophysical properties, false-color composite images were compared to maps of forest stands in the timber compartment. In decreasing order, the most useful correlative forest data are stand basal area, forest age, site condition index, and forest management type. It is found that multipolarization images discriminate variation in tree density and difference in the amount of understory, but do not discriminate between evergreen and deciduous forest types.
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    Radio phase characteristics of terrain from multipolarized synthetic aperture radar data (1985)
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    Publication Date: 2011-08-19
    Description: Recent advances in digital data acquisition and signal processing technology permit simultaneous measurement of the complex (amplitude and phase) radar backscatter from several polarization-diverse antennas. While absolute phase mesurements remain to be analyzed in detail. The differential phase of signals polarized parallel and perpendicular to the plane of incidence provide information on the scattering mechanisms that dominate the interaction of the radio waves with the terrain. Analysis of phase backscatter maps from a typical urban area yields a bimodal distribution with the two peaks separated by approximately 180 degrees, highly indicative of a dominant simple geometric one bounce-two bounce mechanism. Some maps of agricultural areas exhibit a similar distribution, however, other agricultural areas yield a distribution that, while still bimodal, consists of two peaks separated by about 110 deg. Still other agricultural areas exhibit a more complex distribution. All of the observed phase shifts appear to be independent of incidence angle from at least 20 deg to 55 deg, therefore the 110 degree shifts are inconsistent with both the geometric model used for the urban area and with common dielectric slab models.
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    Modelling of backscatter from vegetation layers (1985)
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    Publication Date: 2011-08-19
    Description: A simple way to build up a library of models which may be used to distinguish between the different types of vegetation and ground surfaces by means of their backscatter properties is presented. The curve of constant power received by the antenna (Gamma sphere) is calculated for the given Stokes Scattering Operator, and model parameters are adopted of the most similar library model Gamma sphere. Results calculated for a single scattering model resembling coniferous trees are compared with the Gamma spheres of a model resembling tropical region trees. The polarization which would minimize the effect of either the ground surface or the vegetation layer can be calculated and used to analyze the backscatter from the ground surface/vegetation layer combination, and enhance the power received from the desired part of the combination.
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    Analysis of forest/structure using thematic mapper simulator data (1985)
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    Keywords: EARTH RESOURCES AND REMOTE SENSING
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    Molecular cloud evolution and star formation (1985)
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    Publication Date: 2011-08-19
    Description: The present state of knowledge of the relationship between molecular clouds and young stars is reviewed. The determination of physical parameters from molecular line observations is summarized, and evidence for fragmentation of molecular clouds is discussed. Hierarchical fragmentation is reviewed, minimum fragment scales are derived, and the stability against fragmentation of both spherically and anisotropically collapsing clouds is discussed. Observational evidence for high-velocity flows in clouds is summarized, and the effects of winds from pre-main sequence stars on molecular gas are discussed. The triggering of cloud collapse by enhanced pressure is addressed, as is the formation of dense shells by spherical outflows and their subsequent breakup. A model for low-mass star formation is presented, and constraints on star formation from the initial mass function are examined. The properties of giant molecular clouds and massive star formation are described. The implications of magnetic fields for cloud evolution and star formation are addressed.
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    Far-infrared and submillimeter photometry of evolved stars (1985)
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    Publication Date: 2011-08-19
    Description: Broad-band photometric observations at far infrared and submillimeter wavelengths (lambda is greater than 30 microns and less than 1) provide a unique probe of circumstellar shells in evolved objects and of the mass loss processes which produce them. The problems which these observations explore include: dust properties and dust-to-gas ratios in the outflowing material, the mass and structure of the circumstellar shell, and the pumping mechanism for maser emission. This contribution reviews the early work in this still largely unexploited field and reports results in each of the areas listed above. The dramatic advances forthcoming in this area from the IRAS satellite are previewed along with further progress which will come from the next generation of infrared and submillimeter telescopes.
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    Mass loss from red giants - Infrared spectroscopy (1985)
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    Publication Date: 2011-08-19
    Description: A discussion is presented of IR spectroscopy, particularly high-resolution spectroscopy in the approximately 1-20 micron band, as it impacts the study of circumstellar envelopes. The molecular bands within this region contain an enormous amount of information, especially when observed with sufficient resolution to obtain kinematic information. In a single spectrum, it is possible to resolve lines from up to 50 different rotational/vibrational levels of a given molecule and to detect several different isotopic variants. When high resolution techniques are combined with mapping techniques and/or time sequence observations of variable stars, the resulting information can paint a very detailed picture of the mass-loss phenomenon. To date, near-IR observations have been made of 20 molecular species. CO is the most widely observed molecule and useful information has been gleaned from the observed rotational excitation, kinematics, time variability and spatial structure of its lines. Examples of different observing techniques are discussed in the following sections.
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    The infrared characteristics of circumstellar silicate grains (1985)
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    Publication Date: 2011-08-19
    Description: A theoretical study of the infrared emission from circumstellar shells around late-type giants is made, with the aim of deriving the infrared characteristics of the silicate grains condensing in these shells. A large grid of models has been compared with observations of optically visible Miras, IRC sources and OH/IR stars. From fitting the observed relation between the color temperature and the strength of the 10-micron feature, it is concluded that the ratio of the 3.5 to 10-micron absorption efficiencies of the dust is about 0.25, a factor of 2 less than a previous determination. Detailed modeling of the 2 to 13-micron spectrum of OH 26.5 + 0.6, IRC + 10011 and R Cas yielded a similar ratio. These detailed models also show that the shape of the 10-micron feature, particularly around 8 and 13 microns, varies from source to source. The derived 10-micron feature is narrower for larger dust column densities. These observed differences in the intrinsic shape of the 10-micron feature are not due to differences in size of the condensing particles. Probably they are related to structural or compositional differences in the condensing silicates.
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    Protostellar angular momentum transport by spiral density waves (1985)
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    Publication Date: 2011-08-19
    Description: The application of rotational stability criteria to a specific model of star formation leads to the conclusion that the growth of stellar angular momentum is limited by its transfer to the disk. Excess accreted angular momentum can be transferred by torques connected with spiral density waves induced by even a slight protostellar triaxiality. In addition, viscous damping of the density waves is likely to cause the excess angular momentum to be deposited within a small region close to the protostar. Thus, it would be appropriate to treat that part of the growing protostellar disk beyond the outer Lindblad resonance as an accretion disk with a torque applied to its inner edge. It is noted that this situation is directly relevant to certain models of the evolution of the protosun and solar nebula.
    Keywords: ASTROPHYSICS
    Type: Icarus (ISSN 0019-1035); 64; 435-447
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    The plasma regime at comet Giacobini-Zinner (1985)
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    Publication Date: 2011-08-19
    Description: The paper reviews results on the plasma regime at Comet Giacobini-Zinner obtained by the International Cometary Explorer. The observations are consistent with the existence of a weak shock which may be pulsating, but do not exclude the suggestion that the shock, though present around the subsolar point, is an the process of decaying to a wave on the flanks. 'The pick-up' of cometary ions leads to ion cyclotron, mirror, beam, and electrostatic instabilities which cause strong turbulence in the inner coma.
    Keywords: ASTROPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 5; 12, 1
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    Enhanced rock discrimination using Landsat-5 Thematic Mapper (TM) data (1985)
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    Publication Date: 2011-08-19
    Description: The application of TM data to rock discrimination is discussed. Sixteen specific terrains derived from geologic maps are examined on TM images of the Arabian shield obtained on Apr. 14, 1984; visual enhancement procedures are applied to the images. The rock types observed in the test site are described; the major sedimentary formations in the test area are laterite and sandstone. The data reveal that the layered rocks in the outcrop consist of a variety of metamorphosed volcanics, metamorphosed sediments, and amphibolite, and the intrusive complex is composed of several classes of mafic and acidic rocks.
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    Monitoring vegetation recovery patterns on Mount St. Helens using thermal infrared multispectral data (1985)
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    Publication Date: 2011-08-19
    Description: The eruptions of Mount St. Helens created new surfaces by stripping and implacing large volumes of eroded material and depositing tephra in the blast area and on the flanks of the mountain. Areas of major disturbance are those in the blast zone that were subject to debris avalanche, pyroclastic flows, mudflows, and blowdown and scorched timber; and those outside the blast zone that received extensive tephra deposits. These zones represent a spectrum of disturbance types and intensities that can be indexed by temperature, impact force, and depth of subsequent deposition. This paper describes an application of NASA's Thermal Infrared Multispectral Scanner (TIMS) in monitoring vegetation recovery patterns in disturbed areas. Preliminary study results indicate a significant correlation between measured effective radiant temperature and vegetated/nonvegetated areas, percent vegetation cover, and vegetation type.
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    Identification of linear features in agricultural landscapes through spatial analyses of thermal infrared multispectral scanner data (1985)
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    Publication Date: 2011-08-19
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    The Landsat thematic mapper World Data Base (1985)
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    Publication Date: 2011-08-19
    Description: A World Data Base of potential thematic mapper (TM) scenes was developed to aid in acquisition planning. The World Data Base contains geopolitical, geographic and economic regions along with a format that enables users to find the satellite day, sun angle and cloud cover probability for any month of the year. Scenes that have been acquired by TM and have an average cloud cover of 30 percent of less from July 1982 when TM was launched until the Landsat system was taken over by NOAA in September 1984 are also in the World Data Base. Processed data are referenced in maps and data bases at EROS Data Center; however, a large number of acquistions have never been processed and therefore are not accessible. The World Data Base enables the rapid location of scenes and areas with the least effort making it invaluable in TM scheduling. Users of TM data can use the World Data Base to determine if scenes of interest have been acquired, the acquisition date, and if scenes have been processed to computer-compatible tape (CCT). These uses of the World Data Base make it a valuable tool in the acquisition and location of TM scenes.
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    Ammonia in the hot galactic centre cloud G 1.6-0.025 (1985)
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    Publication Date: 2011-08-19
    Description: As part of an extensive southern survey of interstellar NH3 with the Parkes 64-m radio telescope (with a beamwidth of 81 arcsec), the (1,1), (2,2), and (3,3) transitions have been observed towards the galactic centre molecular cloud Gl.6-0.025. The cloud has an overall size of 10 arcmin, and contains several concentrations with differing velocities. It has several features also observed in other galactic centre clouds, e.g. high optical depths and kinetic temperatures above 50 K.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of Australia, Proceedings (ISSN 0066-9997); 6; 2, 19
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    Extended testing of a general contextual classifier using the massively parallel processor - Preliminary results and test plans (1985)
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    Publication Date: 2011-08-19
    Description: Earlier encouraging test results of a contextual classifier that combines spatial and spectral information employing a general statistical approach are expanded. The earlier results were of limited meaning because they were produced from small (50-by-50 pixel) data sets. An implementation of the contextual classifier on NASA Goddard's Massively Parallel Processor (MPP) is presented; for the first time the MPP makes feasible the testing of the classifier on large data sets (a 12-hour test on a VAX-11/780 minicomputer now takes 5 minutes on the MPP). The MPP is a Single-Instruction, Multiple Data Stream computer, consisting of 16,384 bit serial microprocessors connected in a 128-by-128 mesh array with each element having data transfer connections with its four nearest neighbors so that the MPP is capable of billions of operations per second. Preliminary results are given (with more expected for the conference) and plans are mentioned for extended testing of the contextual classifier on Thematic Mapper data sets.
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    Estimation of soil hydraulic properties with microwave techniques (1985)
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    Publication Date: 2011-08-19
    Description: Useful quantitative information about soil properties may be obtained by calibrating energy and moisture balance models with remotely sensed data. A soil physics model solves heat and moisture flux equations in the soil profile and is driven by the surface energy balance. Model generated surface temperature and soil moisture and temperature profiles are then used in a microwave emission model to predict the soil brightness temperature. The model hydraulic parameters are varied until the predicted temperatures agree with the remotely sensed values. This method is used to estimate values for saturated hydraulic conductivity, saturated matrix potential, and a soil texture parameter. The conductivity agreed well with a value measured with an infiltration ring and the other parameters agreed with values in the literature.
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    Land use mapping using edge density texture measures on Thematic Mapper simulator data (1985)
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    Publication Date: 2011-08-19
    Description: Texture analysis was performed as part of an investigation of the information content of Thematic Mapper (TM) imagery. High altitude aircraft scanner imagery from the Airborne Thematic Mapper (ATM) instrument was acquired over central California and used to simulate TM data. Edge density texture images were constructed by computation of proportions of edge pixels in a 31 x 31 moving window on a near infrared ATM band. A training technique was employed to select computational parameters to maximize the difference between edge density measurements in urban and in rural areas. The results of classification of the texture images showed that urban and rural areas could be distinguished with texture alone, indicating that inclusion of texture in automated classification procedures could significantly improve their accuracy.
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    Multipolarization SAR data for surface feature delineation (1985)
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    Publication Date: 2011-08-19
    Description: This paper presents the techniques and the utility of multipolarization Synthetic Aperture Radar (SAR) data for surface feature delineation. Three channels of ratioed data (VV/HH, VH/HH, and VH/VV) are generated from the HH, VV, and VH polarization data (V = vertical, H = horizontal). The technique assumes redundancy of the VH and HV polarization and only VH polarization is used. The ratioed data are linearly stretched to yield a digital number within a range of 0 to 255. Based on the separability measure for two-class delineation, it was found that (1) the ratioed data resulted in a better delineation of surface features with high like (HH or VV) polarization digital number, and (2) the use of ratioed data provided further information not available from the original three-polarization data. The results suggest an advantage in using the ratioed data and the original three-polarization data for surface feature delineation.
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    What are the best radar wavelengths, incidence angles and polarizations for geologic applications? A statistical approach (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Linear discriminant analysis of multifrequency and multipolarization radar scatterometer data of lava flows and sedimentary rocks indicates that the lava flows can be separated by age and the sedimentary rocks can be discriminated from one another. The optimum wavelengths, polarizations and incidence angles among those available for these problems was determined by the discriminant analysis program. For separation of the lava flows, shorter wavelengths, smaller incidence angles and horizontal polarization are best. A SIR-C radar configuration could provide nearly complete discrimination of these lava flows. Conversely, the longer wavelengths, larger incidence angles and vertical polarization was preferred for sedimentary rocks, perhaps due to the slight vegetation cover. Satisfactory classification of sedimentary rocks requires more radar data than for the lavas. These results are potentially useful both for radar system configuration and for geological applications. The method developed here may provide a rationale for user specification of imaging system parameters.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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    Microwave backscatter and emission observed from Shuttle Imaging Radar B and an airborne 1.4 GHz radiometer (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A soil moisture experiment conducted with the Shuttle Imaging Radar B (SIR-B) is reported. SIR-B operated at 1.28 GHz provided the active microwave measurements, while a 4-beam pushbroom 1.4 GHz radiometer gave the complementary passive microwave measurements. The aircraft measurements were made at an altitude of 330 m, resulting in a ground resolution cell of about 100 m diameter. SIR-B ground resolution from 225 km was about 35 m. More than 150 agricultural fields in the San Joaquin Valley of California were examined in the experiment. The effect of surface roughness height on radar backscatter and radiometric measurements was studied.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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    Overview and highlights of Early Warning and Crop Condition Assessment project (1985)
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    Publication Date: 2011-08-19
    Description: Work of the Early Warning and Crop Condition Assessment (EW/CCA) project, one of eight projects in the Agriculture and Resources Inventory Surveys Through Aerospace Remote Sensing (AgRISTARS), is reviewed. Its mission, to develop and test remote sensing techniques that enhance operational methodologies for crop condition assessment, was in response to initiatives issued by the Secretary of Agriculture. Meteorologically driven crop stress indicator models have been developed or modified for wheat, maize, grain sorghum, and soybeans. These models provide early warning alerts of potential or actual crop stresses due to water deficits, adverse temperatures, and water excess that could delay planting or harvesting operations. Recommendations are given for future research involving vegetative index numbers and the NOAA and Landsat satellites.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 60
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    Forest discrimination with multipolarization imaging radar (1985)
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    Publication Date: 2011-08-19
    Description: The relations between polarization signatures and biophysical characteristics through a range of different forest environments were investigated using airborne synthetic-aperture (SAR) images acquired at L-band on March 1, 1984 in South Carolina. SAR data acquired in four linear polarization states with 10-m spatial resolution were encoded as color composite images and compared to US Forest Service forest stand data. The most useful correlative forest data were stand basal area, forest age, site condition index, and forest management type. It is found that the multipolarization images discriminate variation in tree density or difference in the amount of understory, but no evidence has been found for discrimination between evergreen and deciduous forest types.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 61
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    Structure of terrestrial impact craters from SIR-B radar data - Preliminary results (1985)
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    Publication Date: 2011-08-19
    Description: The structure in and around the Charlevoix and Deep Bay impact craters was analyzed by comparing SIR-B radar image lineament maps with maps derived from Landsat data and aerial photography. Relationships revealed include the discovery in the Deep Bay lineament distribution of a mode, of slightly different location and size to that determined by aerial photography, which correlates with the regional glacial trend. The Deep Bay regional glacial trend displays a much more prominent signature in the aerial photography than in the radar data, confirming the influence of radar look direction on the interpretation of lineament distribution and orientation. Effects from the impact event are noted in the radar images of both craters, with lineaments of one km or less appearing to be associated with the rim structure.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 62
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    Estimation of biophysical properties of forest canopies through inversion of microwave scatterometer data (1985)
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    Publication Date: 2011-08-19
    Description: A method for estimating the biophysical properties of a forest canopy through inversion of microwave scatterometer data is discussed. A C-band scatterometer flown over an aspen site in northern Minnesota during 19 days from May 2 to October 20, 1984, was modified to enable continuous recording of the range of the target. This provided the backscatter cross section as a function of range and was used to study scattering processes within the canopy. The remote estimates of HH, VV, and HV extinction coefficient values agreed well with the estimates obtained with the use of an active radar calibrator.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 63
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    Remote sensing techniques for the detection of soil erosion and the identification of soil conservation practices (1985)
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    Publication Date: 2011-08-19
    Description: The following paper is a summary of a number of techniques initiated under the AgRISTARS (Agriculture and Resources Inventory Surveys Through Aerospace Remote Sensing) project for the detection of soil degradation caused by water erosion and the identification of soil conservation practices for resource inventories. Discussed are methods to utilize a geographic information system to determine potential soil erosion through a USLE (Universal Soil Loss Equation) model; application of the Kauth-Thomas Transform to detect present erosional status; and the identification of conservation practices through visual interpretation and a variety of enhancement procedures applied to digital remotely sensed data.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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    Passive microwave soil moisture research (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The AgRISTARS Soil Moisture Project has made significant progress in the quantification of microwave sensor capabilities for soil moisture remote sensing. The 21-cm wavelength has been verified to be the best single channel for radiometric observations of soil moisture. It has also been found that other remote sensing approaches used in conjunction with L-band passive data are more successful than multiple wavelength microwave radiometry in this application. AgRISTARS studies have also improved current understanding of noise factors affecting the interpretability of microwave emission data. The absorption of soil emission by vegetation has been quantified, although this effect is less important than absorption effects for microwave radiometry.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 65
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    A calculation of the Rosseland mean opacity of dust grains in primordial solar system nebulae (1985)
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    Publication Date: 2011-08-19
    Description: The Rosseland mean opacity owing to grains was calculated as a function of temperature and density for nebulae having solar elemental abundances. The values of the mean opacity were evaluated with a generalized formulation allowing for anisotropic scattering. The values of the mean opacity do not depend sensitively on the choice of the particle size distribution function, provided that there are few particles having sizes in excess of several tens of microns. The results indicate that thermal convection in primordial nebulae occurs over broader ranges of altitudes at low temperatures than at high temperatures, and for size distributions for which extensive aggregation has not yet occurred.
    Keywords: ASTROPHYSICS
    Type: Icarus (ISSN 0019-1035); 64; 471-492
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    Diagnostics of solar and astrophysical plasmas - Dependent on autoionization phenomena (1985)
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    Publication Date: 2011-08-19
    Description: The application of autoionization calculations to problems in solar and astrophysical plasma diagnostics is discussed. Attention is given to space plasmas having high spectral resolution, particularly in the wavelength region between about 300 and 1100 A. It is shown that atomic resonance data can be used to calculate many of the spectral line intensities in solar plasmas in order to obtain information concerning the physical properties of the emitting gas, including temperature, density, ionization balance, and atmospheric structure and dynamics. Recent spectral observations of nonsolar plasmas are also discussed. A list of the major high-resolution astrophysical plasma spectrometers and spectrographs is provided.
    Keywords: ASTROPHYSICS
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    Comparison of the information contents of LANDSAT TM and MSS data (1985)
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    Publication Date: 2011-08-19
    Description: A communications-theory approach is taken to analyze the dispersion and concentration of signal values in various data spaces, irrespective of specific class membership. Entropy is used to quantify information, and mutual information is used to measure the information represented by subsets of spectral variables. Several different comparisons of information content are made. These include comparisons of system design capacities, of data volumes occupied by agricultural data in the spaces defined by original bands and by transformed spectral (Tasseled Cap) variables, of the information contents of original bands and Tasseled Cap variables, and of the information contents of TM and MSS for the given agricultural data sets. Also, the effects of sample size, scene content, and quantization level are examined.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Study on Spectral(Radiometric Characteristics of the Thematic Mapper for Land Use Applications; p 39-48
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  • 68
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    Anatomy of a cosmic-ray neutrino source and the Cygnus X-3 system (1985)
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    Publication Date: 2011-08-19
    Description: The effects of an intense beam of ultra-high energy cosmic rays from a compact object in the Cygnus X-3 binary system hitting the companion star, and of the subsequent production of secondary neutrinos, are examined. A maximum allowable beam luminosity of about 10 to the 42nd erg/s is found for a system containing a 1-10 solar mass main sequence target star. The proton beam must heat a relatively small area of the target star to satisfy observational constraints on the resulting stellar wind. With such a model, the neutrino to gamma-ray flux ratio of about 1000 can result from a combination of gamma-ray absorption and a large neutrino to gamma-ray duty cycle ratio. It is found that the high density of the atmosphere resulting from compression by the beam leads to pion cascading and a neutrino spectrum peaking at 1-10 GeV energies.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 316; 418-420
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    The physical implications of an isothermal model for the hot intracluster medium (1985)
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    Publication Date: 2011-08-19
    Description: HEAO-1 A-2 and Einstein Observatory IPC observations of 15 clusters of galaxies have been used to measure the isothermal beta-model parameters, and the parameters are compared with those derived from model fits to the X-ray images. The physical constraints imposed on this model by existing optical data, the implied gas mass, and the gas contribution to the binding cluster mass are addressed. Values of beta less than unity are obtained, consistent with results from X-ray imaging data. This is interpreted to imply that the gas extends out to 8-10 core radii, about 2-3 Mpc. The isothermal gas mass can be as large as 60 percent of the virial mass for some clusters. This contradicts the fundamental assumption that the cluster potential is determined by an unseen mass which is given by the King approximation to an isothermal sphere, and it is concluded that the isothermal model is a nonphysical model.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 292; 441-446
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  • 70
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    High-energy X-ray observations of the Galactic center region (1985)
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    Publication Date: 2011-08-19
    Description: The region within five degrees of the Galactic center was observed in high-energy X-rays on November 12, 1977, and it is concluded that the emission definitely comes from more than one source. At least five 2-10 keV sources are important: the transient A1743 - 322, the binary GX 1 + 4, the bulge sources GX 3 + 1 and GX 5 - 1, and A1742 - 294. The composite spectrum of all the sources agrees with the continuum measured 12 days earlier by Leventhal, MacCallum, and Stang (1978) in the 70-250 keV range but, if extrapolated to higher energies, would be softer than and weaker than the HEAO 1 continuum observed in September 1977 or HEAO 3 continuum observed in the fall of 1979.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 290; 557-567
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  • 71
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    On fast X-ray rotators with long-term periodicities (1985)
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    Publication Date: 2011-08-19
    Description: The support of previous SAS 3 spacecraft observations by new data gathered by the Monitor Proportional Counter aboard the HEAO 2 spacecraft indicates that the pulse period history of the 13.5 sec-pulsing X-ray source LMC X-4 is consistent with standard accretion and torque models only if LMC X-4 is a fast rotator for which the accretion torques nearly cancel. This result leads to a neutron star magnetic field strength estimate of about 1.2 x 10 to the 13th G. Strong evidence is noted for Her X-1's status as a fast rotator, while SMC X-1 is probably an intermediate-to-fast rotator. In the context of slaved disk models for these objects, it is noted that the precession periods expected for the companion stars are significantly longer than the observed 1-2 month time scales; slaved disk models are thereby undermined.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 290; 487-495
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  • 72
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    Application of Thematic Mapper data to corn and soybean development stage estimation (1985)
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    Publication Date: 2011-08-19
    Description: A model, utilizing direct relationship between remotely sensed spectral data and the development stage of both corn and soybeans has been proposed and published previously (Badhwar and Henderson, 1981; and Henderson and Badhwar, 1984). This model was developed using data acquired by instruments mounted on trucks over field plots of corn and soybeans as well as satellite data from Landsat. In all cases, the data was analyzed in the spectral bands equivalent to the four bands of Landsat multispectral scanner (MSS). In this study the same model has been applied to corn and soybeans using Landsat-4 Thematic Mapper (TM) data combined with simulated TM data to provide a multitemporal data set in TM band intervals. All data (five total acquisitions) were acquired over a test site in Webster County, Iowa from June to October 1982. The use of TM data for determining development state is as accurate as with Landsat MSS and field plot data in MSS bands. The maximum deviation of 0.6 development stage for corn and 0.8 development stage for soybeans is well within the uncertainty with which a field can be estimated with procedures used by observers on the ground in 1982.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment (ISSN 0034-4257); 17; 197-201
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    Electrosphere of an aligned magnetized neutron star (1985)
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    Publication Date: 2011-08-19
    Description: A fundamentally new self-consistent solution for the electrosphere of an aligned magnetized neutron star is presented. Unlike previous models the electrospheres are finite in extent. This avoids the light cylinder problem. The results may provide a basis for pulsar models.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 213; 43P-49P
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    MgS grain component in circumstellar shells (1985)
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    Publication Date: 2011-08-19
    Description: In this letter, far-infrared spectrophotometry (30-55 microns) and photometry (53-200 microns) are presented which define, for the first time, the long wavelength limit of the previously unidentified 30 micron emission feature found in certain extreme carbon star spectra. The spectral similarities are sufficiently similar to those of solid MgS that MgS is proposed to be the band carrier. This is interpreted as the first direct evidence that chemical surface reactions occur on dust grains in circumstellar environments. The presence of MgS indicates that either the oxygen abundance is relatively low and/or the sulfur abundance is high in extreme carbon stars.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 290; L35-L39
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    Laboratory infrared spectra of predicted condensates in carbon-rich stars (1985)
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    Publication Date: 2011-08-19
    Description: Laboratory spectra and mass absorption coefficients of MgS, CaS, FeS, SiS2, FeS2, Fe3C, and a commercial iron carbide are presented over the wavelength range 125-15 microns. These spectra confirm that MgS is the most likely source of the unidentified 30-micron emission in carbon-rich sources and that FeS, Fe3C, and 'iron carbide' cannot be responsible for this feature although they could contribute to the continuum in this region. CaS and FeS2 may contribute to the 30-micron feature; however, both higher resolution and higher precision astronomical observations are needed before their presence can be established. SiS2 has a peak near 22 microns and therefore cannot be a significant component of the dust in such regions.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 290; L41-L43
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    Polycyclic aromatic hydrocarbons and the unidentified infrared emission bands - Auto exhaust along the Milky Way (1985)
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    Publication Date: 2011-08-19
    Description: The unidentified infrared emission features (UIR bands) are attributed to a collection of partially hydrogenated, positively charged polycyclic aromatic hydrocarbons (PAHs). This assignment is based on a spectroscopic analysis of the UIR bands. Comparison of the observed interstellar 6.2 and 7.7-micron bands with the laboratory measured Raman spectrum of a collection of carbon-based particulates (auto exhaust) shows a very good agreement, supporting this identification. The infrared emission is due to relaxation from highly vibrationally and electronically excited states. The excitation is probably caused by UV photon absorption. The infrared fluorescence of one particular, highly vibrationally excited PAH (chrysene) is modeled. In this analysis the species is treated as a molecule rather than bulk material and the non-thermodynamic equilibrium nature of the emission is fully taken into account. From a comparison of the observed ratio of the 3.3 to 11.3-micron UIR bands with the model calculations, the average number of carbon atoms per molecule is estimated to be about 20. The abundance of interstellar PAHs is calculated to be about 2 x 10 to the -7th with respect to hydrogen.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 290; L25-L28
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  • 77
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    The R Aquarii system at optical and radio wavelengths (1985)
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    Publication Date: 2011-08-19
    Description: New continuum observations of all radio components of the R Aquarii system at 2, 6, and 20 cm are reported which allow determination of polarization properties, integrated flux levels, spectral indices, and hence the emission mechanisms of the individual components. Complementary wide-band optical observations are also reported to help determine the nature and structure of the compact double radio source (CDRS) and the R Aquarii radio jet. The results of these observations are discussed in detail with regard to models currently or previously proposed for the R Aquarii system. It is concluded that the compact H II region spectral index is about +0.6, indicative of a thermal and optically thick expanding wind from the long-period variable. The radio jet emission is shown to be optically thin, thermal, cospatial with optical emission, and stable over the last few years. The CDRS is shown to be an extragalactic background object.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 289; 765-767
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  • 78
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    Experimental evidence for spring and autumn windows for the detection of geobotanical anomalies through the remote sensing of overlying vegetation (1985)
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    Publication Date: 2011-08-19
    Description: It is pointed out that in many regions of the world, vegetation is the predominant factor influencing variation in reflected energy in the 0.4-2.5 micron region of the spectrum. Studies have, therefore, been conducted regarding the utility of remote sensing for detecting changes in vegetation which could be related to the presence of mineralization. The present paper provides primarily a report on the results of the second year of a multiyear study of geobotanical-remote-sensing relationships as developed over areas of sulfide mineralization. The field study has a strong experimental design basis. It is proceeded by first delineating the boundaries of a large geographic region which satisfied a set of previously enumerated field-site criteria. Within this region, carefully selected pairs of mineralized and nonmineralized test sites were examined over the growing season. The experiment is to provide information about the spectral and temporal resolutions required for remote-sensing-geobotanical exploration. The obtained results are evaluated.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: International Journal of Remote Sensing (ISSN 0143-1161); 6; 195-216
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  • 79
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    Preliminary results of a quantitative comparison of the spectral signatures of Landsat Thematic Mapper (TM) and Modular Optoelectronic Multispectral Scanner (MOMS). (1985)
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    Publication Date: 2011-08-19
    Description: Operationally acquired Thematic Mapper and experimental MOMS-01 data are evaluated quantitatively concerning the systems spectral response and performance for geoscientific applications. Results show the two instruments to be similar in the spectral bands compared. Although the MOMS scanner has a smaller IFOV, it has a lower modulation transfer function performance for small, low contrast features as compared to Thematic Mapper. This deficiency does not only occur when MOMS was switched to the low gain mode. It is due to the CD arrays used (ITEK CCPD 1728).
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ESA Proceedings of the Third International Colloquium on Spectral Signatures of Objects in Remote Sensing; p 335-341
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    The First International Satellite Land-Surface Climatology Project (ISLSCP) Field Experiment (FIFE) (1985)
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    Publication Date: 2011-08-19
    Description: The International Satellite Land Surface Climatology Project (ISLSCP) will verify the use of satellite data for the estimation of land-surface properties through field experiments using point measurements on the ground and areal measurements from aircraft overflights. In addition to validating satellite estimates of surface properties, it studies approaches for obtaining areal averages of the radiation, moisture and heat fluxes made using remotely sensed data. The procedure suggested combines the surface point measurements of the fluxes with the aircraft areal observations using a surface energy balance model to interpolate between the point estimates of these fluxes and calculate area-averaged quantities. The surface parameters to be estimated from aircraft observations include: surface radiation temperature, albedo, land cover or vegetation index, and surface soil moisture (the latter to be obtained using passive and active microwave approaches). The area-averages of the surface properties are compared with satellite data where possible. The First ISLSCP Field Experiment is planned for l987 at a site having relatively uniform vegetation cover in the central great plains of the USA. for 1987 at a site having relatively uniform vegetation cover in the central great plains of the USA.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ESA Proceedings of the Third International Colloquium on Spectral Signatures of Objects in Remote Sensing; p 321-325
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  • 81
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    Cropland soil moisture estimates derived from dual polarization 1.66 centimeter passive microwave imagery from Nimbus 7 (1985)
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    Publication Date: 2011-08-19
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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    High-angular resolution observations of stellar binary systems (1985)
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    Publication Date: 2011-08-19
    Description: A long-term program designed to investigate the spatial structure of centimetric radio emission from close binary systems using multistation VLBI array is discussed. Eleven binaries, including eight RS CVn systems, Algol, LSI 61 deg 303, and Cyg X-1, have been detected. The measured brightness temperatures vary from T(B) about 10 exp 8.5 K during periods of low activity to T(B) about 10 exp 10.5 K during flares. Extensive observation of a few sources has shown that the spatial structure is 'core-halo' with linear dimensions of about a stellar radius and the binary system, respectively. The observations are consistent with gyrosynchrotron emission of mildly relativistic electrons in magnetic fields of about 10 exp 1.5 + or - 0.5 gauss. The core sources appear to be optically thick, while the halo component is optically thin.
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  • 83
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    The dynamical history of comet Halley (1985)
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    Publication Date: 2011-08-19
    Description: The history of the attempts to predict the motion of comet Halley is outlined and the importance of the so-called nongravitational forces acting upon this comet is emphasized. Recent orbital work of the International Halley Watch Astrometry Network is reviewed. Comet Halley's transverse nongravitational parameter is positive and nearly constant with time suggesting that the comet is in direct rotation without precession of the spin pole. The nongravitational effects are consistent with the vaporization of water ice from the comet's nucleus and long term integrations suggest that the comet has been in its present orbit for at least 16,000 years and probably much longer.
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    Morphological and physical characteristics of the Virgo Cluster - First results from the Las Campanas photographic survey (1985)
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    Publication Date: 2011-08-19
    Description: Preliminary results are presented of a photographic survey of the Virgo cluster to the faintest convenient limit of the Las Campanas du Pont 2.5 m reflector, performed in order to study the complexity of both the surface and velocity distributions within the central 6 degree radius region. The survey is described and the resulting Catalog is discussed, and the frequency of galaxy types found and listed in the Catalog is described. The physical properties of the dwarfs are summarized, and luminosity functions are given separately for each morphological type. The progressive change of (MBT) faintward along the morphological sequence from Sc I through Sm and Im types is shown, leading to a calibration of the de Vaucouleurs Lambda luminosity index and a determination of its intrinsic dispersion. The preliminary results on the distribution of galaxies of all types in the two principal subclustering regions found are summarized, and the velocity distributions over the face of the 6 degree core are discussed for the various galaxy types.
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    Analysis of data acquired by Shuttle Imaging Radar SIR-A and Landsat Thematic Mapper over Baldwin County, Alabama (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Seasonally compatible data collected by SIR-A and by Landsat 4 TM over the lower coastal plain in Alabama were coregistered, forming a SIR-A/TM multichannel data set with 30 m x 30 m pixel size. Spectral signature plots and histogram analysis of the data were used to observe data characteristics. Radar returns from pine forest classes correlated highly with the tree ages, suggesting the potential utility of microwave remote sensing for forest biomass estimation. As compared with the TM-only data set, the use of SIR-A/TM data set improved classification accuracy of the seven land cover types studied. In addition, the SIR-A/TM classified data support previous finding by Engheta and Elachi (1982) that microwave data appear to be correlated with differing bottomland hardwood forest vegetation as associated with varying water regimens (i.e., wet versus dry).
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 86
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    Near infrared leaf reflectance modeling (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Near infrared leaf reflectance modeling using Fresnel's equation (Kumar and Silva, 1973) and Snell's Law successfully approximated the spectral curve for a 0.25-mm turgid oak leaf lying on a Halon background. Calculations were made for ten interfaces, air-wax, wax-cellulose, cellulose-water, cellulose-air, air-water, and their inverses. A water path of 0.5 mm yielded acceptable results, and it was found that assignment of more weight to those interfaces involving air versus water or cellulose, and less to those involving wax, decreased the standard deviation of the error for all wavelengths. Data suggest that the air-cell interface is not the only important contributor to the overall reflectance of a leaf. Results also argue against the assertion that the near infrared plateau is a function of cell structure within the leaf.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 87
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    The NASA/JPL multipolarization SAR aircraft program (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The NASA/JPL aircrft program has been in existence for more than a decade. However, during the past two years, there has been a dramatic increase in the capability and scientific utility of this system as an L-band, 4-polarization synthetic aperture radar (SAR) system has become operational. The system is capable of simultaneously and coherently acquiring four independent complex polarization measurements for every pixel in the image. This capability has been exploited by a number of experimenters to generate several new data types that appear to contain significantly more information than was previously available from single or dual polarized SAR systems. The system will ultimately be capable of estimating the entire complex scattering matrix for every pixel on the ground. Within the next year the system will be extended to C-band so that it will be possible to simultaneously acquire 4-polarization imagery at L-band and C-band. This system will be the prototype for the SIR-C experiment that will have similar capabilities and be flown on the Space Shuttle in 1989.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 88
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    Variograms and spatial variation in remotely sensed images (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Research is presented that is aimed at developing a link or connection between ground scenes and spatial variation in images. The link is established through the use of models of scenes and a measure of spatial variation - the variogram. The approach used to explore the nature of spatial variation in remotely sensed images can be thought of as a 'bottom up' approach because it starts with a model of the scene and works toward the characteristics of a remotely sensed image derived from the scene. To date, observed images at two resolutions for each of three kinds of environment have been used to evaluate the use of variograms in real images. The images are from forests, residential, and agricultural environments. One resolution used is 30 m from the Thematic Mapper or Thematic Mapper Simulator. For each environment also there is fine resolution data from the range of 0.15-2.5 m. It is noted that variograms from these images show considerable structure. Work continues on checking the validity of the disk model (a way of representing trees and their shadows).
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 89
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    Vegetation assessment using a combination of visible, near-IR and thermal-IR AVHRR data (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Twelve hour temperature difference (thermal inertia) maps generated by rectifying and registering ascending (day) passes and descending (night) passes of the NOAA-7 Advanced Very High Resolution Radiometer (AVHRR) are compared to vegetation index maps generated from the visible and near IR data from the day pass of that satellite. There appears to be significant and unique information concerning surface characteristics in the temperature difference data on the 1 km scale of the AVHRR. A scatter diagram is provided which shows the pattern of day-night temperature difference compared to vegetation index for irrigated agriculture, dry rangeland, lakes, wet areas and burned rangeland. A detailed description of the techniques employed to provide the day-night temperature maps is provided.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 90
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    Topographic mapping from interferometric synthetic aperture radar observations (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Interferometric SAR observations are a basis for the generation of high resolution topographic maps of a region through the interpretation of interference fringes. The combination of height, along-track, and slant range measurements is sufficient for rectification of the radar imagery for cartographic applications, in addition to furnishing an accurate determination of the scene topography. Topographic maps have been derived on the basis of data recorded by both aircraft and Seasat-A satellite radars. A comparison of the maps obtained with U.S. Geological Survey Contour maps indicates a high degree of correlation between two sets of altitude data.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 91
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    Bipolar nebulae and mass loss from red giant stars (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Observations of several bipolar nebulae are used to learn something of the nature of mass loss from the probable red-giant progenitors of these nebulae. Phenomena discussed are: (1) probable GL 2688's optical molecular emissions; (2) newly discovered very high velocity knots along the axis of OH 0739 - 14, which reveal evidence for mass ejections of + or 300 km/s from the M9 III star embedded in this nebula; (3) the bipolar structure of three extreme carbon stars, and the evidence for periodic mass ejection in IRC + 30219, also at high speed (about 80 km/s); and (4) the curious cool TiO-rich region above Parsamian 13, which may represent the very recent shedding of photospheric material from a cool, oxygen-rich giant. Several general key questions about bipolar nebulae that relate to the process of mass loss from their progenitor stars are raised.
    Keywords: ASTROPHYSICS
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  • 92
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    Infrared studies of the bipolar nebula OHO739 (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Infrared studies have been made of the M9 giant OHO739, which is embedded in a bipolar nebula, in order to study the structure and density distribution of the circumstellar disk, and preliminary results are reported. The degree of polarization across the 3.1 micron ice band in an 8 arcsec beam centered at the 2.2 micron peak is found to increase with extinction in the ice band, as expected for a bipolar scattering nebula. A distance of 2 kpc is inferred from the tilt angle of the bipolar axis and phase lag measurements of the OH maser. Maps made in the K band and in narrow bands at 2.85, 3.1, and 3.5 microns by raster-scanning OHO739 are presented. In all maps, the object is clearly elongated along the bipolar axis. Patterns of increases and decreases in extinction in the object are inferred to indicate that ice particles are widespread through the nebula and not just concentrated in the disk.
    Keywords: ASTROPHYSICS
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  • 93
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    Hydrogen deficiency and mass loss from AGB stars (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Theoretical studies predict that mass loss from stars should accelerate once stars on the AGB begin thermal pulsations (TP). It has been discovered that the stars on this part of the AGB are apparently hydrogen deficient. This development may be related to the mass loss predicted by theory. Hydrogen deficiency is also supported by the nondetection of H2 in non-Mira stars, S stars, and carbon stars. The possibility that the observed apparent hydrogen deficiency has resulted from a mass loss process is considered. Observations indicate that TP-AGB stars become hydrogen deficient before the Mira phase.
    Keywords: ASTROPHYSICS
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  • 94
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    Spectral constraints on models of gas in clusters of galaxies (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The HEAO 1A2 spectra of clusters of galaxies are used to determine the temperature profile which characterizes the X-ray emitting gas. Strong evidence of nonisothermality is found for the Coma, A85, and A1795 clusters. Properties of the cluster potential which binds the gas are calculated for a range of model parameters. The typical binding mass, if the gas is adiabatic, is 2-4E14 solar masses and is quite centrally concentrated. In addition, the Fe abundance in Coma is .26 + or - .06 solar, less than the typical value (.5) found for rich clusters. The results for the gas in Coma may imply a physical description of the cluster which is quite different from what was previously believed.
    Keywords: ASTROPHYSICS
    Type: Space Science Reviews (ISSN 0038-6308); 40; 681-688
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  • 95
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    H0323+022 - Classification as a BL Lac and EXOSAT coordinated observations (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The object H0323+022 (Doxsey et al. 1983) has been shown to be a BL Lac object by virtue of a diversity of observational characteristics at radio, optical, and X-ray wavelengths, in agreement with the conclusion of Margon and Jacoby (1984). Multi-frequency coordinated observations of this highly variable object with EXOSAT in September 1984 found it to be in a faint quiescent state (approximately 1/3 micron-Jy at approximately 5 keV and V = 16.55). Preliminary results from the latter observations are presented.
    Keywords: ASTROPHYSICS
    Type: Space Science Reviews (ISSN 0038-6308); 40; 613-617
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  • 96
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    The discovery of a 25 min regular modulation in the X-ray flux from 2S0142 + 61 (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A 13 hr observation of 2S0142 + 61 on August 27, 1984 by EXOSAT shows the X-ray flux of 2S0142 + 61 to be modulated with a period of 1456+/-6 s. The 1-10 keV spectrum is two component with an approximately 0.7 keV thermal and 0.0 energy index power law, with 30 percent of the total luminosity in the thermal component. The spectrum is absorbed by about 1 x 10 to the 22nd H per sq cm. Only the hard component is pulsed with a 3 to 10 keV peak to mean amplitude of 35 percent. Below 2 keV the modulation is less than a few percent. The total 1-10 keV luminosity is 3.5 x 10 to the 32nd erg/s for a distance of 100 pc. Possible optical counterparts are discussed.
    Keywords: ASTROPHYSICS
    Type: Space Science Reviews (ISSN 0038-6308); 40; 157-162
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  • 97
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    Inclusion of specular reflectance in vegetative canopy models (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A detailed comparison of the observed soybeans and corn canopy reflectance with that calculated from three vegetative canopy reflectance models have shown systematic angular deviations. A likely cause of these effects is noninclusion of leaf specular reflectance. In this paper a formulation to calculate the component of canopy specular reflectance as a function of incident solar and view zenith angles, leaf area index, leaf angle distribution, and leaf specular reflectance has been developed. The SAIL model has been modified to include this component and the results are compared with an extensive observational data set on soybeans. It is shown that the systematic differences between the SAIL model and observations dependent on scattering azimuth are removed. An analysis of variance shows model improvement of 30 percent over the uncorrected SAIL model.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); GE-23; 731-736
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  • 98
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    Evaluation of a canopy reflectance model for LAI estimation through its inversion (1985)
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    Publication Date: 2011-08-19
    Description: A technique for estimating leaf area indices (LAIs) based on bidirectional canopy reflectance (CR) data is applied to three plant canopies: a naturally growing healthy soybean canopy; and a clumped and tufted orchardgrass canopy, respectively. The CR data were collected using a PARABOLA instrument which is capable of acquiring complete sky-and-ground looking hemispheres in 11 seconds. The model fit and LAI estimates were good for the soybean and clumped orchardgrass canopies, but poor for the tufted orchardgrass canopy when the maximum zenith angle was less than 50 percent. It is shown that the biophysical parameter estimation based on CR measurements applied well to homogeneous herbaceous vegetation types, while better CR models are needed to adequately represent discontinuous plant canopies.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); GE-23; 674-684
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  • 99
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    Modeling the radiant transfers of sparse vegetation canopies (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The scattering dynamics of sparse vegetation canopies were studied within the framework of the three-dimensional radiative transfer model of Kimes (1984). The model was upgraded by including an algorithm for the anisotropic scattering of a soil boundary. Validation of the model was carried out using measured directional reflectance data for two canopies exhibiting typical scattering behavior with low and intermediate vegetation density. The canopies were: an orchard grass canopy; and a hard wheat canopy. A number of factors were found contributing to the final reflectance distribution of the canopies, including: (1) the strong anisotropic scattering properties of the soil; (2) the geometric effect of the vegetation probability gap function on the soil anisotropy and solar irradiance; and (3) the anisotropic scattering of vegetation which is controlled by the phase function and the layering of leaves. The application of the theoretical results to the development of earth-observing sensor systems is discussed.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); GE-23; 695-704
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  • 100
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    The relative importance of aerosol scattering and absorption in remote sensing (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Previous attempts to explain the effect of aerosols on satellite measurements of surface properties for the visible and near-infrared spectrum have emphasized the amount of aerosols without consideration of their absorption properties. In order to estimate the importance of absorption, the radiances of the sunlight scattered from models of the earth-atmosphere system are computed as functions of the aerosol optical thickness and absorption. The absorption effect is small where the surface reflectance is weak, but is important for strong reflectance. These effects on classification of surface features, measuring vegetation index, and measuring surface reflectance are presented.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); GE-23; 625-633
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