Search NASA⌕ Search

SEARCH · Search NASA

Results for “INFERENCE”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Zonal velocity and texture in the Jovian atmosphere inferred from Voyager images

Smith et al. (1970) have described Jupiter's changing appearance at resolutions down to 10 km over intervals as small as 1 h. Examples of small-scale convection, rapid variations of features, and complex interactions of closed vortices were given. In the present paper, these results are extended to include measurements of the latitudinal profile of zonal (eastward) velocity, from which the absolute vorticity gradient is estimated. Also, a classification scheme based on texture (i.e., the patterns of small features visible at resolutions of 100 km or better) is proposed.

Ingersoll, A. P.↗
NASA NTRS1979

Coronal holes inferred from the Fleurs East-West solar scans

East-West solar scans produced daily on 692 and 1415 MHz are analyzed for the period 1968 to 1973. The analysis confirms that coronal holes are stable features displaying significantly reduced electromagnetic emission which can persist for many solar rotations. The coronal hole observations are summarized in a series of tables.

Ferguson, B. G.↗
NASA NTRS1979

Alteration in CM carbonaceous chondrites inferred from modal and chemical variations in matrix

The modal abundance of matrix in CM chondrites appears to vary from 57-85 vol%. The concentrations of volatile elements that should occur in matrix remain approximately constant despite differences in the proportions of matrix, suggesting that the differing matrix contents may not be real primary variations but are optical effects due to aqueous alteration processes that make other petrologic components unrecognizable. Apparent matrix content can be used as a qualitative measure of the degree of alteration experienced by each CM chondrite. Fe/Si ratios in matrices decrease progressively with increasing alteration due to the formation of new phyllosilicate phases with higher Mg/Fe ratios and optically recognizable opaque minerals that are not counted as matrix. The aqueous alteration process in CM chondrites appears to have been largely isochemical if the bulk meteorites are considered as the reacting systems, although depletion patterns and isotopic anomalies indicate open-system behavior for a few highly mobile components.

Mcsween, H. Y., Jr.↗
NASA NTRS1979

On the inference of properties of Saturn's Ring E from energetic charged particle observations

The paper demonstrates that information about Saturn's Ring E particle size is potentially obtainable from observations of Saturnian trapped radiation. It is shown that observations of the radial dependence of the intensities, energy spectra, electron-to-proton intensity ratio, and pitch angle distributions of energetic charged particles trapped outside of Ring A can potentially provide information (1) on the existence of Ring E, (2) on the effective size of the particulate matter therein, and (3) on the magnitude of the radial diffusion coefficient for energetic particles. A parametric study of these possibilities is specialized to the characteristics of the University of Iowa detectors on Pioneer 11 which was scheduled to make a close encounter with Saturn in 1979.

Thomsen, M. F.↗
NASA NTRS1980

Properties of African squall lines inferred from time-lapse satellite imagery

Analysis of 48 h of time-lapse satellite imagery of a family of squall lines in Africa links the phenomena with a characteristic cloud cluster and with a wind field perturbation which is enhanced in passing through an African easterly wave trough. A thin 'arc line' of low-level developing cumulus, a salient feature of the squall lines on the imagery, is shown to occur at the front boundary of the mesoscale/convective scale subsidence. Analysis of the wind field indicates that a squall line is associated with a vorticity center in the mid-level easterly flow which accompanies the mesoscale subsidence which, in turn, contributes to further forced ascent of subcloud air along the front of the squall line into convective towers which merge into an extensive anvil. The squall lines evolved through a life cycle of 6 to 12 h while the larger cloud cluster and wind perturbation lasted over 48 h. The magnitude of the vertical mass exchange suggests that squall-line families contribute significantly to the tropical energy balance.

Fortune, M.↗
NASA NTRS1980

Vertical distribution of aerosol extinction cross section and inference of aerosol imaginary index in the troposphere by lidar technique

The paper reports on vertical profiles of aerosol extinction and backscatter in the troposphere which were obtained from multi zenith angle lidar measurements. It is reported that a direct slant path solution was found to be not possible due to horizontal inhomogeneity of the atmosphere. Attention is given to the use of a regression analysis with respect to zenith angle for a layer integration of the angle dependent lidar equation in order to determine the optical thickness and aerosol extinction-to-backscatter ratio for defined atmospheric layers and the subsequent evaluation of cross-section profiles.

Spinhirne, J. D.↗
NASA NTRS1980

Infrared radiative properties of tropical cirrus clouds inferred with aircraft measurements

Longwave emissivities and the vertical profile of cooling rates of tropical cirrus clouds are determined using broadband hemispheric irradiance data. Additionally, a broadband mass absorption coefficient is defined and used to relate emissivity to water content. The data used were collected by the National Center for Atmospheric Research (NCAR) Sabreliner during the GARP Atlantic Tropical Experiment (GATE) in the summer of 1974. Three case studies are analyzed showing that these tropical cirrus clouds approached an emissivity of 1.0 within a vertical distance of 1.0 km. Broadband mass absorption coefficients ranging from 0.076 to 0.096 sq m per g are derived. A comparison of these results with other work suggests that tropical cirrus cloud emissivities may be significantly larger than heretofore believed. Ice water content of the clouds were deduced from data collected by a one-dimensional particle spectrometer. Analyses of the ice water content and the observed particle size distributions are presented.

Griffith, K. T.↗
NASA NTRS1980

Properties of the Io plasma torus inferred from Voyager EUV data

A physical model for the Io plasma torus is constructed to explain the EUV radiative emission observed by the Voyager UV spectrometer. Electron impact excitation rate coefficients for electronic transitions of S III, S IV, O II and O III are calculated by the method of distorted waves (Davis, Kepple, and Blaha, 1976); these coefficients account for the asymmetric shape of the 686 A feature. It is concluded that the electron gas must have a distribution function with a non-Maxwellian tail. An approximate representation of the distribution function as two temperature components requires a cold component of 3.5-4 eV and density of 2000 per cu cm and a hot component of about 100 eV and density of 50-100 per cu cm to satisfy observational constraints.

Strobel, D. F.↗
NASA NTRS1980

Inference of the boundary layer structure over the oceans from satellite infrared measurements

Remote infrared spectral measurements in the 8-13 micron m window region, at a resolution about 3 cm/1, contain useful information about the water vapor and temperature stratification of the atmosphere within the first few kilometers above the water surface. Two pieces of information are retrieved from the spectral measurements: precipitable water vapor in the atmosphere, from the depth of the line structure between 8 and 9 micron m due to water vapor lines; and sea surface temperature, from the variation of brightness temperature between 11 and 13 micron m. Together, these two pieces of information can signify either the presence of a deep moist convective layer or the prevalence of stable conditions, such as caused by temperature inversions, which inhibit moist convection. A simple infrared radiative transfer model of the 9 micron m water vapor lines was developed to validate the method. With the help of this model and the Nimbus 4 infrared interferometer spectrometer data, a gross picture of the planetary boundary layer for different seasons over the global oceans is deduced. The important regions of the trade wind inversion and the intertropical convergence zones over all the oceans are clearly identified with this method. The derived information is in reasonable agreement with some observed climatological patterns over the oceans.

Prabhakara, C.↗
NASA NTRS1980

Lunar near-surface shear wave velocities at the Apollo landing sites as inferred from spectral amplitude ratios

The horizontal-to-vertical amplitude ratios of the long-period seismograms are reexamined to determine the shear wave velocity distributions at the Apollo 12, 14, 15, and 16 lunar landing sites. Average spectral ratios, computed from a number of impact signals, were compared with spectral ratios calculated for the fundamental mode Rayleigh waves in media consisting of homogeneous, isotropic, horizontal layers. The shear velocities of the best fitting models at the different sites resemble each other and differ from the average for all sites by not more than 20% except for the bottom layer at station 14. The shear velocities increase from 40 m/s at the surface to about 400 m/s at depths between 95 and 160 m at the various sites. Within this depth range the velocity-depth functions are well represented by two piecewise linear segments, although the presence of first-order discontinuities cannot be ruled out.

Horvath, P.↗
NASA NTRS1980

Interior structure of Saturn inferred from Pioneer 11 gravity data

The structure of Saturn is studied via a fourth-order theory for rotating planets and equations of state for the envelope which depend parametrically on the helium abundance, on the starting temperature for the adiabat, and on adopted forms of the pressure-density curve in the region of transition from molecular to metallic hydrogen. Models are constrained by the values of J2 and J4 obtained from the Pioneer-Saturn celestial mechanics experiment. Equations of state are tested by computing Jupiter models, which can now be subjected to a more stringent comparison with observed zonal harmonics. It is found that Saturn has a low-density hydrogen-helium envelope with no evidence for enhancement of H2O, CH4, or other abundant compounds. Such compounds are presumably located near the core. The helium mass abundance for Saturn's envelope appears to be in the range of approximately 0.12 to 0.19, but this result is very model-dependent. The helium abundance in the envelope of Jupiter is apparently very similar to that of Saturn.

Hubbard, W. B.↗
NASA NTRS1980

Moon and earth - Compositional differences inferred from siderophiles, volatiles, and alkalis in basalts

A comparison of RNAA analyses of 18 trace elements in 25 low-Ti lunar and 10 terrestrial oceanic basalts indicated that the volatiles such as Ag, Bi, and Br are depleted in lunar basalts by nearly constant factors of 0.026 relative to terrestrial basalts. This constancy is not consistent with models that derive the moon's volatiles from partial recondensation of the earth's mantle or from partial degassing of a captured body; it is consistent with models which derive planetary volatiles from a thin veneer of C-chondrite material. Chalcogens (Se and Te) have almost constant and identical abundances in lunar and terrestrial basalts; siderophiles show abundant Ni in lunar basalts, while Ir, Re, Ge, and Au are depleted.

Wolf, R.↗
NASA NTRS1980

Dynamic properties of the thermosphere inferred from Pioneer Venus mass spectrometer measurements

The data obtained by the Pioneer Venus spectrometer experiments indicate that the day-night temperature contrast on Venus is associated with wind velocities of about 200 m/s which transport oxygen, helium, and hydrogen toward the night side. A mass exchange with the mesosphere commensurate with an eddy diffusion coefficient of 3 x 10 to the 7th is required to buffer the horizontal advection so as to reproduce the observed day time bulge in oxygen and the small diurnal variations in helium. The observed time response and magnitude of the day-night density variations require transport processes to be effective over time periods between five and ten days, implying a superrotation rate or prevailing winds in excess of 50 m/s at the equator. Nonlinear mass transport results in wave steepening and contributes to the amplification of the density extrema in hydrogen and helium.

Mayr, H. G.↗
NASA NTRS1981

Composition of hot ions /0.1-16 keV/e/ as observed by the GEOS and ISEE mass spectrometers and inferences for the origin and circulation of magnetospheric plasmas

The composition of hot magnetospheric plasma through different regions of the magnetosphere is described on the basis of mass spectrometer measurements by the GEOS 1, GEOS 2, and ISEE-1 spacecraft. Coordinated composition measurements on the different spacecraft also provide information on the spatial and temporal characteristics of the plasma during storms. Data on ion origins are also provided.

Balsiger, H.↗
NASA NTRS1981

Inference of the ring current ion composition by means of charge exchange decay

The analysis of data from the Explorer 45 (S3-A) electrostatic analyzer in the energy range 5-30 keV has provided some new results on the ring current ion composition. It has been well established that the storm time ring current has a decay time of several days, during which the particle fluxes decrease nearly monotonically. By analyzing the measured ion fluxes during the several day storm recovery period and assuming that beside hydrogen other ions were present and that the decays were exponential in nature, three separate lifetimes for the ions were established. These fitted decay lifetimes are in excellent agreement with the expected charge exchange decay lifetimes for H(+), O(+) and He(+) in the energy and L value range of the data.

Smith, P. H.↗