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At least 667 records · Page 37
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Interpretation of spatial and temporal variations of hydrogen quadrupole absorptions in the Jovian atmosphere observed during the 1972 apparition

Results are reported for a systematic investigation of temporal and spatial variations of hydrogen quadrupole lines formed in the Jovian atmosphere, which was performed by measuring the strengths of the S(1) lines of H2 (3,0) and (4,0) quadrupole bands at several points on the Jovian disk during the 1972 apparition. The observations support the hypothesis that the strength of the (3,0) S(1) line varies significantly with time, suggest the possibility of short-term temporal variation in the strength of the (4,0) line, and indicate that the H2 line strengths vary remarkably little from limb to limb in the equatorial region. A Galatry line-shape profile is calculated, and a radiative-transfer analysis is carried out using the Henyey-Greenstein phase function for single particle scattering. It is shown that the observations are consistent with a multilayer atmospheric model having an optically thin upper cloud deck separated by a stratum of nonscattering gas from an optically thick lower cloud.

Hunt, G. E.↗
NASA NTRS1977

Variational calculations of vibrational properties of ozone

A variational method is used to obtain vibrational-rotational properties for ozone from an experimental quartic force field. Band positions, average structures, matrix elements for calculating infrared intensities, and effective rotational constants are reported for (O-16)3 and its O-18 isotopic species. Also, the degree to which the vibrational energies and properties are converged is investigated as a function of the basis set parameters and basis set size, and of the method of obtaining the Hamiltonian matrix elements. A convenient procedure for assigning the vibrational states is developed for variational vibrational wavefunction expansions.

Carney, G. D.↗
NASA NTRS1977

High resolution spectroscopy of the disk chromosphere. V - Space-time variations observed simultaneously in seven lines

Time sequence spectroscopic observations of the quiet solar chromosphere along a 200 Mm strip near the center of the disk were reduced to obtain 30 min of data. Oscillations appear in most of the observations in selected photospheric and chromospheric lines, but rarely in continuum observations. At a given point, the oscillations may be prominent or weak, they are never regular in time, and there is no unique relationship between the amplitudes at different heights. There are several examples of granules which apparently excite a burst of short period oscillations. By considering the line shift and intensity variations of all the lines, a working model is derived for the velocity field and related temperature variation.

Cram, L. E.↗
NASA NTRS1976

Thorium and uranium variations in Apollo 17 basalts, and K-U systematics

It is found that Apollo 11 low-K and in particular Apollo 17 mare basalts show a wide range of Th/U ratios unlike other rocks; such variations cannot be explained by near surface crystal fractionation. A two-stage fractional crystallization-partial melting model involving a clinopyroxene cumulate as the major phase can explain the variations in Th/U ratios. Due to the Sm-Nd systematics constraint, several source cumulates are invoked to explain the observed Th/U continuum.

Laul, J. C.↗
NASA NTRS1977

Radial variation of lunar crater rim topography

The paper presents results of determinations of variations of rim topography as a function of range from the crater rim for a group of morphologically fresh craters. It is found that the rate at which exterior crater topography converges with the surrounding surface is highly variable among different radial directions at individual craters as well as between different craters, and that at several craters, oblique impact appears to have contributed to azimuthal elevation/range variations.

Settle, M.↗
NASA NTRS1977

Saturn - Long-term variation of H2 and CH4 absorptions

Results are presented for observations of various H2 quadrupole lines and CH4 absorption bands in spectra of Saturn obtained with a coude scanner at each apparition since 1969. The data are found to indicate a long-term variation in Saturn's H2 equivalent widths, a seasonal dependence of H2 line strength, and a fairly steady increase in CH4 absorption during the period from 1973 to 1976. A possible correlation between planetary shading and the strength of H2 absorption features is discussed along with seasonal variations in Saturn's NH3 cloud deck and atmospheric models that correspond to the observed H2 equivalent widths. It is suggested that: (1) significant shadowing by the rings may cause dynamical atmospheric activity due to the occurrence of a temperature gradient in the penumbral boundaries of the ring shadow in the planet's upper atmosphere; (2) cooling in the shadow may be a source of a high-altitude CH4 mist; and (3) spreading of this mist over the globe by advective winds would reduce the H2 and CH4 absorptions, as observed.

Trafton, L.↗
NASA NTRS1977

Diurnal variations in the thermosphere. II - Temperature, composition, and winds

The fundamental diurnal component of temperature, composition and wind fields is discussed for the thermosphere, the results delineated in terms of energy sources in the lower atmosphere, mesosphere and thermosphere, illustrating their relative significance. The diurnal component in the composition of H, He, O, O2 and Ar has been analyzed in terms of effects from thermal expansion in diffusive equilibrium and transport processes associated with chemistry, wind circulation, exospheric flow and escape. Next to thermal expansion, wind-induced diffusion is the single most important process; it dominates the diurnal variations of He and prevails in the variations of O, O2 and Ar below 200 km.

Mayr, H. G.↗
NASA NTRS1976

Latitudinal variations in the solar wind

There are two classes of latitudinal solar wind variations - those which are an imprint of coronal processes, and those which are internally generated within the solar wind. An axisymmetric description of the latitudinal variations is presented. As an example, a large polar coronal hole is discussed, with attention to directed meridional flow in the corona out to five solar radii, temperature and density characteristics in a coronal hole and beyond, temperature effects in the interplanetary medium, internally generated meridional flow in the interplanetary medium, and the detection of polar hole material in the ecliptic at 1 AU.

Suess, S. T.↗
NASA NTRS1977

An unusual aspect of solar wind speed variations during solar cycle 20

Geomagnetic records from 1868 through 1975 indicate that geomagnetic activity during 1973-1975 was unusually enhanced for that phase of the sunspot cycle (5-7 years after solar maximum). Previous work indicates that long-term variations in geomagnetic activity are closely coupled to long-term variations in the bulk flow speed of the solar wind. Thus, it is inferred that reported averages of the solar-wind speed for the 1973-1975 era are unusually large for that phase of the sunspot cycle.

Gosling, J. T.↗
NASA NTRS1977

Variation in animal response to different toxicants

The variation in response of different lots of male Swiss albino mice to pyrolysis effluents from surgical cotton and from bisphenol A polycarbonate, and to pure carbon monoxide, is discussed. The variation appeared to be less with the pyrolysis gases from polycarbonate than with pure carbon monoxide.

Hilado, C. J.↗
NASA NTRS1977

A technique to correct for sample thickness variations for use with IDAPS X-ray radiograph analysis

The Image Data Processing System (IDAPS) at the Marshall Space Flight Center is used to analyze radiographs of metal samples to qualitatively and quantitatively map compositional variations across the samples. When the X-ray radiographs are of samples having thickness variations, corrections must be made to accomplish compositional analysis. A correction technique is described for cylindrical samples and is applied to radiographs of SPAR Experiment 74-18. Uncorrected and corrected images are shown.

Schafer, C. F.↗
NASA NTRS1977

Analysis of magnetic fields using variational principles and CELAS2 elements

Prospective techniques for analyzing magnetic fields using NASTRAN are reviewed. A variational principle utilizing a vector potential function is presented which has as its Euler equations, the required field equations and boundary conditions for static magnetic fields including current sources. The need for an addition to this variational principle of a constraint condition is discussed. Some results using the Lagrange multiplier method to apply the constraint and CELAS2 elements to simulate the matrices are given. Practical considerations of using large numbers of CELAS2 elements are discussed.

Frye, J. W.↗
NASA NTRS1976

Observed and theoretical variations of atmospheric ozone

Results are summarized from three areas of ozone research: (1) continued analysis of the global distribution of total ozone to extend the global ozone atlas to summarize 15 years (1957-72) of ground based observations; (2) analysis of balloon borne ozonesonde observations for Arosa, Switzerland, and Hohenpeissenberg, Germany (GFR); (3) contined processing of the (Orbiting Geophysical Observatory-4) satellite data to complete the analysis of the stratospheric ozone distribution from the available OGO-4 data. Results of the analysis of the total ozone observations indicated that the long term ozone variation have marked regional patterns and tend to alternate with season and hemisphere. It is becoming increasingly clear that these long period changes are associated with large scale variations in the general upper atmosphere circulation patterns.

London, J.↗
NASA NTRS1976

Cruise aerodynamics of USB nacelle/wing geometric variations

Experimental results are presented on aerodynamic effects of geometric variations in upper surface blown nacelle configurations at high speed cruise conditions. Test data include both force and pressure measurements on two and three dimensional models powered by upper surface blowing nacelles of varying geometries. Experimental results are provided on variations in nozzle aspect ratio, nozzle boattail angle, and multiple nacelle installations. The nacelles are ranked according to aerodynamic drag penalties as well as overall installed drag penalties. Sample effects and correlations are shown for data obtained with the pressure model.

Braden, J. A.↗
NASA NTRS1978

Regional variations in upper mantle compressional velocities beneath southern California 1. Post-shock temperatures: Their experimental determination, calculation, and implications, 2.

The compressional velocity within the upper mantle beneath Southern California is investigated through observations of the dependence of teleseismic P-delays at all stations of the array on the distance and azimuth to the event. The variation of residuals with azimuth was found to be as large as 1.3 sec at a single station; the delays were stable as a function of time, and no evidence was found for temporal velocity variations related to seismic activity in the area. These delays were used in the construction of models for the upper mantle P-velocity structure to depths of 150 km, both by ray tracing and inversion techniques. The models exhibit considerable lateral heterogeneity including a region of low velocity beneath the Imperial Valley, and regions of increased velocity beneath the Sierra Nevada and much of the Transverse Ranges. The development is described of a technique for the experimental determination of post-shock temperatures, and its application to several metals and silicates shocked to pressures in the range 5 to 30 GPa. The technique utilizes an infra-red radiation detector to determine the brightness temperature of the free surface of the sample after the shock wave has passed through it.

Raikes, S. A.↗
NASA NTRS1978

Feature discrimination/identification based upon SAR return variations

A study of the statistics of The look-to-look variation statistics in the returns recorded in-flight by a digital, realtime SAR system are analyzed. The determination that the variations in the look-to-look returns from different classes do carry information content unique to the classes was illustrated by a model based on four variants derived from four look in-flight SAR data under study. The model was limited to four classes of returns: mowed grass on a athletic field, rough unmowed grass and weeds on a large vacant field, young fruit trees in a large orchard, and metal mobile homes and storage buildings in a large mobile home park. The data population in excess of 1000 returns represented over 250 individual pixels from the four classes. The multivariant discriminant model operated on the set of returns for each pixel and assigned that pixel to one of the four classes, based on the target variants and the probability distribution function of the four variants for each class.

Rasco, W. A., Sr.↗
NASA NTRS1977

Annual variation in temperature and composition of the thermosphere and upper mesosphere

A three-dimensional circulation model, including UV (O2 dissociation) and EUV sources, is used to study the wind field and the effects of temperature and composition on annual thermospheric variations. The results are compared to those of OGO-6 and AE-C. Within an 800-1200 K temperature range, summer to winter temperature variation is studied as a function of solar activity. It is found that the model correctly predicts H, He, O, N2, O2, and Ar measurements. It is suggested that a small winter maximum in mesospheric temperature is caused by large-scale circulation induced by EUV heating. This effect, however, is masked by the energy released in O2 dissociation. The annual temperature amplitude and the winter oxygen bulge are noted to increase with increasing solar activity, whereas the winter helium bulge is noted to decrease with enhanced exospheric return flow. It is felt that the dependence of the F2 region winter anomaly on solar activity may be significantly affected by the solar activity effect in atomic oxygen.

Mayr, H. G.↗
NASA NTRS1978

Compatibility of seasonal variations in mid-latitude thermospheric models at solar maximum and low geomagnetic activity

Satellite drag data, in situ mass spectrometer data, Fabry Perot interferometer data, and incoherent scatter data were used to produce models of the concentration of atomic oxygen and molecular nitrogen in the thermosphere and of the exospheric temperature. Incoherent scatter data from two stations near 45 deg N were used. The three techniques provide similar patterns for the annual variations of the atomic oxygen concentration at 400 km, and the mean annual temperatures are within 20 K of each other for five of the six models involved. Four of the models are in good agreement concerning the annual temperature variation. There is fair agreement between incoherent scatter models and mass spectrometer models for the N2 concentrations at 400 km but disagreement between these models and the satellite drag model. It is shown that most disagreements can be resolved by changing both the vertical temperature profile and the lower-thermosphere oxygen concentration in the direction indicated by previous incoherent scatter measurements.

Alcayde, D.↗