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  • ASTROPHYSICS  (1,375)
  • GEOPHYSICS  (1,099)
  • Biochemistry and Biotechnology  (691)
  • 1995-1999
  • 1985-1989  (2,135)
  • 1980-1984
  • 1975-1979  (1,030)
  • 1940-1944
  • 1987  (2,135)
  • 1977  (1,030)
Collection
Keywords
Publisher
Years
  • 1995-1999
  • 1985-1989  (2,135)
  • 1980-1984
  • 1975-1979  (1,030)
  • 1940-1944
Year
  • 1
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    Kerogen structures in recently-deposited algal mats at Laguna Mormona, Baja California: A model system for the determination of kerogen structures in ancient sediments (1977)
    In:  CASI
    Details
    Publication Date: 2005-02-28
    Keywords: GEOPHYSICS
    Type: Res. in the Space Sci., Vol. 2, No. 1; 29 p
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  • 2
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    Gamma rays, cosmic rays, and galactic structure (1977)
    In:  CASI
    Details
    Publication Date: 2006-08-09
    Description: Observations of cosmic and gamma radiation by SAS-2 satellite are summarized and analyzed to determine processes responsible for producing observed galactic radiation. In addition to the production of gamma rays in discrete galactic objects such as pulsars, there are three main mechanisms by which high-energy (greater than 100 MeV) radiation is produced by high-energy interactions involving cosmic rays in interstellar space. These processes, which produce what may be called diffuse galactic gamma-rays, are: (1) the decay of pi mesons produced by interactions of cosmic ray nucleons with interstellar gas nuclei; (2) the bremsstrahlung radiation produced by cosmic ray electrons interacting in the Coulomb fields of nuclei of interstellar gas atoms; and (3) Compton interactions between cosmic ray electrons and low-energy photons in interstellar space.
    Keywords: ASTROPHYSICS
    Type: The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 315-346
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  • 3
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    Gamma rays and large scale galactic structure (1977)
    In:  CASI
    Details
    Publication Date: 2006-08-09
    Description: Gamma ray astronomy is now beginning to provide a new look at the galactic structure and the distribution of cosmic rays, both electrons and nucleons, within the galaxy. The observations are consistent with a galactic spiral-arm model in which the cosmic rays are linearly coupled to the interstellar gas on the scale of the spiral arms. The agreement between the predictions of the model and the observations for regions of the plane where both 21-cm and 2.6-mm CO surveys exist emphasizes the need to extend these observations to include the entire plane. Future gamma-ray observations with more sensitivity and better angular resolutions, combined with these radio surveys, should shed new light on the distribution of cosmic rays, the nature of the galaxy, and the location and intensity of the spiral arms.
    Keywords: ASTROPHYSICS
    Type: The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 301-314
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  • 4
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    Galactic distribution of pulsars (1977)
    In:  CASI
    Details
    Publication Date: 2006-08-09
    Description: The density distributions of pulsars in luminosity, period, Z-distance, and galactocentric distance were derived, using a uniform sample of pulsars detected during a 408-MHz pulsar survey at Jodrell Bank. There are indications of a fine-scale structure in the spatial distributions and evidence that there is a general correlation with other galactic populations and the overall spiral structure. The electron layer in our galaxy is shown to be wider than the pulsar layer and uniform on a large scale. The number of pulsars in the galaxy has been estimated and used to derive the pulsar birthrate.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 265-282
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  • 5
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    Gamma rays and supernova explosions (1977)
    In:  CASI
    Details
    Publication Date: 2006-08-09
    Description: Thermal radiation associated with the explosion of supernovae is investigated. High temperature is required to produce copious gamma radiation of this sort. It appears that type 11 supernovae do not release much of their energy as gamma ray continuum radiation.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 257-264
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  • 6
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    Remarks on the overall distribution of hydrogen in the galactic disk (1977)
    In:  CASI
    Details
    Publication Date: 2006-08-09
    Description: The degree of saturation characterizing low altitude emission observations of H(I) and the optical depth corrections to the derived column and volume densities are discussed. The amount of fine-scale velocity and spatial structure diluted by the instrumental limitations of the presently available surveys are described. The general problem of detailed mapping of H(I) in the galaxy is explored. Comparison is made between the distribution of H(I) and that of CO and several other galactic tracers. Atomic hydrogen is unique in its distribution, instead of being typical of many Population I constituents. As defined by atomic hydrogen, the galactic disk has a diameter fully twice as large as that defined by the ionized and molecular states of hydrogen, as well as by other molecules, supernova remnants, pulsars, gamma-radiation, synchroton radiation, and the youngest stars. It is also less confined to the galactic equator than most of the other constituents. The degree of small scale structure apparent in the molecular observations is much greater than that in the H(I) observations.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 163-188
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  • 7
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    Gamma ray pulsars (1977)
    In:  CASI
    Details
    Publication Date: 2006-08-09
    Description: Data from the SAS-2 high-energy gamma-ray experiment reveal the existence of four pulsars emitting photons above 35 MeV. An attempt is made to explain the gamma-ray emission from these pulsars in terms of an electron-photon cascade that develops in the magnetosphere of the pulsar. Although there is very little material above the surface of the pulsar, the very intense magnetic fields (10 to the 12th power gauss) correspond to many radiation lengths which cause electrons to emit photons by magnetic bremsstrahlung and which cause these photons to pair-produce. The cascade develops until the mean photon energy drops below the pair-production threshold which is in the gamma-ray range; at this stage, the photons break out from the source.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 109-118
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  • 8
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    Radiation mechanisms and magnetospheric structure of pulsars (1977)
    In:  CASI
    Details
    Publication Date: 2006-08-09
    Description: Considerations made in developing a model of pulsars are explored. Observational data seems to support the argument that pulsar magnetospheres may contain large masses of plasma. The cascade process resulting from pair creation enables one to interpret the X-ray emission from the Crab and Vela pulsars as synchrotron radiation. On the other hand, the optical radiation from the Crab pulsar is best understood as coherent curvature radiation. Radio emission is interpreted as curvature radiation produced by charge bunches moving along magnetic-field lines. Certain tests of this model are proposed.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 99-108
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  • 9
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    Investigating the role of the land surface in explaining the interannual variation of the net radiation balance over the Northwest Sahara and sub-Sahara (1987)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: How much of the interannual variation in the satellite derived radiation balance can be purely attributed to changes taking place at the land surface, was examined. The role of surface latent heating was examined in relation to its control of the precipitation pattern from one year to the next.
    Keywords: GEOPHYSICS
    Type: Investigating the Role of the Land Surface in Explaining the Interannual Variation of the Net Radiation Balance over the Western Sahara and Sub-Sahara; 5 p
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  • 10
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    Experience with the inversion of Nimbus 4 BUV measurements to retrieve the ozone profile (1977)
    In:  CASI
    Details
    Publication Date: 2006-05-22
    Description: The relative merits of pressure increment and partial derivative formulations of the ozone inversion problem are discussed briefly. The height range of validity of the retrieved ozone profile and the effects of adding wavelengths to or of dropping wave-length from the inversion system are indicated. Illustrative results are presented for profiles retrieved from BUV data using Backus-Gilbert, minimum information (Twomey), and quasi-optimum procedures.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 577-597
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  • 11
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    The inversion of stratospheric aerosol and ozone vertical profiles from spacecraft solar extinction measurements (1977)
    In:  CASI
    Details
    Publication Date: 2006-05-22
    Description: The inversions of multi-channel solar extinction measurements have been analyzed for the 0.35-1.0 micron wavelength region to retrieve stratospheric aerosol and ozone vertical profiles using both the constrained linear inversion scheme and the iterative scheme. The inversions of the multi-wavelength solar extinction data obtained from spacecraft have been analyzed based on the inversion of computer simulated data using various atmospheric models with differing amounts of aerosol and ozone in the stratosphere. The sensitivities of the inversion schemes to different experimental errors are discussed in terms of accuracy and resolution of the retrieved profiles.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 505-527
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  • 12
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    Application of modified Twomey techniques to invert lidar angular scatter and solar extinction data for determining aerosol size distributions (1977)
    In:  CASI
    Details
    Publication Date: 2006-05-22
    Description: Polarization properties of the angularly scattered laser light from a volume of air are used to determine the size distribution of the aerosol particles within the volume by the use of appropriate inversion techniques. Similar techniques are employed to determine a mean size distribution of the particulates within a vertical column through the atmosphere from determinations of the aerosol optical depth as a function of wavelength. In both of these examples, a modification of an inversion technique originally described by Twomey has been employed. Details of this method are presented as well as results from actual measurements employing bistatic lidar and solar radiometer.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 469-503
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  • 13
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    Application of statistical inversion to ground-based microwave remote sensing of temperature and water vapor profiles (1977)
    In:  CASI
    Details
    Publication Date: 2006-05-22
    Description: Surface-based observations of downwelling microwave thermal emission are related to temperature and humidity profiles via a standard integral equation of radiative transfer. Both in clear and in cloudy atmospheres, statistical inversion techniques are used to retrieve profiles from a data vector of brightness observations and surface meteorological constraints. For the clear case, accuracy predictions and profile retrievals are illustrated for: (1) single frequency angular scanned data; (2) multi-frequency angular scanned data; and (3) multi-frequency zenith data. For the last case predicted and achieved accuracies were compared in a recently conducted radiometric experiment. Retrievals of cloud contaminated radiometric data are elaborated.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 395-427
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  • 14
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    Comparison of linear inversion methods by examination of the duality between iterative and inverse matrix methods (1977)
    In:  CASI
    Details
    Publication Date: 2006-05-22
    Description: Linear numerical inversion methods applied to atmospheric remote sounding generally can be categorized in two ways: (1) iterative, and (2) inverse matrix methods. However, these two categories are not unrelated; a duality exists between them. In other words, given an iterative scheme, a corresponding inverse matrix method exists, and conversely. This duality concept is developed for the more familiar linear methods. The iterative duals are compared with the classical linear iterative approaches and their differences analyzed. The importance of the initial profile in all methods is stressed. Calculations using simulated data are made to compare accuracies and to examine the dependence of the solution on the initial profile.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 325-360
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  • 15
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    Analytic model approach to the inversion of scattering data (1977)
    In:  CASI
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    Publication Date: 2006-05-22
    Description: An analytic model approach is applied to several simple atmospheric inversion problems. This method gives a sharp determination of aerosol size distribution parameters. It is shown that this analytic approach, together with ground level point sampling data measurements, can be used to infer information on the tropospheric ozone profile.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 297-324
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  • 16
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    Inversion of infrared limb emission measurements for temperature and trace gas concentrations (1977)
    In:  CASI
    Details
    Publication Date: 2006-05-22
    Description: Limb emission measurements are characterized by sharp weighting functions at high altitudes, and for temperature determinations, strongly nonlinear dependence of the weighting function on the temperature. Several methods for inverting this type of measurement have been described and used, including iterative, statistical, nonlinear and approximate direct approaches. These approaches are described and advantages and disadvantages of each are outlined.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 195-216
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  • 17
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    Inverse solution of the pseudoscalar transfer equation through nonlinear matrix inversion (1977)
    In:  CASI
    Details
    Publication Date: 2006-05-22
    Description: Nonlinear matrix inversion operators have been developed which, applied to observed radiances, infer maximal information regarding atmospheric scattering parameters and vertical distribution of radiant sources and sinks. The algorithm has the attractive feature of noise discrimination, attributing instrumental errors to extra-atmospheric sources.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 139-153
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  • 18
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    Backus-Gilbert theory and its application to retrieval of ozone and temperature profiles (1977)
    In:  CASI
    Details
    Publication Date: 2006-05-22
    Description: The inversion method provides a quantitative evaluation of the trade-off between vertical resolution of a retrieved profile and formal root-mean-square (rms) error due to measurement noise propagation. The problem of retrieving the top-side ozone profile from backscattered ultraviolet (BUV) measurements is considered. For measurements of the type currently being obtained with the Nimbus 4 and AE-E BUV experiments, it is found that a vertical resolution of approximately 0.75 scale height can be achieved for a formal volume mixing ratio profile error of 10%. Other examples include treatments of the retrieval of temperature profiles from measurements in the 15 micron CO2 absorption band for both the terrestrial and Martian atmospheres. Finally, the method is applied to the problem of retrieving temperature profiles of the Jovian planets from measurements in the far infrared pressure induced H2 lines to be obtained from the Mariner Jupiter/Saturn fly-by missions.
    Keywords: GEOPHYSICS
    Type: Inversion Methods in Atmospheric Remote Sounding; p 155-193
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  • 19
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    Statistical principles of inversion theory (1977)
    In:  CASI
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    Publication Date: 2006-05-22
    Description: Statistical methods are used to deal with the inverse problem of radiative transfer. All the available information about an unknown profile can be expressed in the form of values of functions of that profile and error estimates of these values. Estimation theory shows how these values are combined to give an estimate of the unknown profile and its error covariance. Many inversion methods are expressed in this form, although the error estimate is not usually carried out. Practical applications are described, both for inversion of individual profiles, and the global analysis of satellite data.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 117-138
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  • 20
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    Some aspects of the inversion problem in remote sensing (1977)
    In:  CASI
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    Publication Date: 2006-05-22
    Description: Several commonly used methods for inversion--constrained linear inversion, synthesis (Backus-Gilbert) methods and nonlinear iterative techniques for the Chahine type--are discussed. It is demonstrated that a very close connection exists between Backus-Gilbert solutions and those given by constrained linear inversion. A number of examples of the application of such methods are presented, showing that resolution is not greatly different for quite different algorithms, a result quite in accord with general theoretical considerations: more resolution can be achieved at the expense of introducing greater a priori bias in the procedure.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 41-65
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  • 21
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    Review of radiative transfer methods in scattering atmospheres (1977)
    In:  CASI
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    Publication Date: 2006-05-22
    Description: The radiative transfer in a scattering plane-parallel atmosphere is discussed, considering the exact analytical, the computational and the approximate methods. Some results of numerical comparisons are given. Finally, the difficulties of realistic atmospheric models are emphasized.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 21-40
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  • 22
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    Hybrid methods are helpful (1977)
    In:  CASI
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    Publication Date: 2006-05-22
    Description: Multiple scattering problems in a plane layer often permit the convenient use of different methods joined together. Sample numerical results to illustrate this point refer to X- and Y-functions, asymptotic fitting, the small-loss approximations, polarization in high orders, and photon path distribution.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 1-19
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  • 23
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    National geodetic satellite program, part 1 (1977)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Determinations of tracking station locations and the gravitational constant of the earth, based on Doppler-tracking data from lunar and planetary spacecraft are presented. Two-way Doppler data obtained by the Deep Space Network of the Jet Propulsion Laboratory (JPL) were used. The Deep Space Station instrumentation that JPL employed is described. How the stations were located is detailed, and the data used are discussed. Results are given together with an analysis of the errors.
    Keywords: GEOPHYSICS
    Type: Natl. Geodetic Satellite Program, Pt. 1; p 249-292
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  • 24
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    National geodetic satellite program, part 1 (1977)
    In:  CASI
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    Publication Date: 2006-01-16
    Description: The Applied Physics Laboratory (APL) space research program was directed toward modeling the gravitational field of the earth from an analysis of the Doppler shifts on the transmitted frequencies of the satellites as obtained by the tracking stations. Emphasis is on the satellites involved and the methods used in accomplishing this aim.
    Keywords: GEOPHYSICS
    Type: NASA, Washington Natl. Geodetic Satellite Program, Pt. 1; p 89-138
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  • 25
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    Introduction: National geodetic satellite program, part 1 (1977)
    In:  CASI
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    Publication Date: 2006-01-16
    Description: Background for the National Geodetic Satellite Program (NGSP) is presented. An historical summary of the program and its technical structure is given. The technical structure of the program is described in enough detail that the reader can relate the work of the individual contributors to each other and to the NGSP.
    Keywords: GEOPHYSICS
    Type: NASA, Washington Natl. Geodetic Satellite Program, Pt. 1; p 3-85
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  • 26
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    National geodetic satellite program, part 1 (1977)
    In:  CASI
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    Publication Date: 2006-01-16
    Description: The major accomplishments of the GEOS-B, C-band systems project is assessed. The project objectives are given, namely: (1) primary objectives that must be met for project success; (2) secondary objectives that were sufficiently important to warrant serious consideration; and (3) other objectives that were important to the project and for which additional effort would be desirable. The primary objectives are presented and discussed in detail.
    Keywords: GEOPHYSICS
    Type: Natl. Geodetic Satellite Program, Pt. 1; p 487-524
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  • 27
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    National geodetic satellite program, part 1 (1977)
    In:  CASI
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    Publication Date: 2006-01-16
    Description: Equipment and techniques were evaluated operationally, by the Department of Defense, during the National Geodetic Satellite Program (NGSP). The theory, instrumentation, and data reduction methods used are described. Results obtained during the NGSP are given.
    Keywords: GEOPHYSICS
    Type: NASA, Washington Natl. Geodetic Satellite Program, Pt. 1; p 139-245
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  • 28
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    Simultaneous field measurements of biogenic emissions of nitric oxide and nitrous oxide (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Seasonal and diurnal emissions of NO and N2O from agricultural sites in Jamestown, Virginia and Boulder, Colorado are estimated in terms of soil temperature; percent moisture; and exchangeable nitrate, nitrite, and ammonium concentrations. The techniques and procedures used to analyze the soil parameters are described. The spatial and temporal variability of the NO and N2O emissions is studied. A correlation between NO fluxes in the Virginia sample and nitrate concentration, temperature, and percent moisture is detected, and NO fluxes for the Colorado site correspond with temperature and moisture. It is observed that the N2O emissions are only present when percent moisture approaches or exceeds the field capacity of the soil. The data suggest that NO is produced primarily by nitrification in aerobic soils, and N2O is formed by denitrification in anaerobic soils.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 965-976
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  • 29
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    Ozone isotope measurements in the stratosphere (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Mass spectrometer measurements of ozone made during two balloon flights included its heavy isotopes at mass 49 and 50. Both flights were flown during the day and during summer from Palestine, TX. At float altitudes above 42 km the enrichments in heavy ozone were 41 percent and 23 percent, respectively. The enrichment appears to be mass independent since, at high altitudes, both 49 and 50 show the same enhancement. During the descent the enrichment in heavy ozone decreased, faster during the first flight than during the second, reaching values between 15 and 20 percent above 30 km. Near and below this altitude another increase is observed. During a night flight, previously reported, an enhancement in heavy ozone of over 40 percent at 32 km was found, decreasing both toward higher and lower altitudes.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 14; 80-83
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  • 30
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    Nucleus of comet Halley as a torque-free rigid rotator (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A model for the rotation of the nucleus of comet Halley is proposed on the assumption that the nucleus is homogeneous and a torque-free rigid rotator. It spins about its long axis with a period of 7.4 days, while this axis precesses about a fixed direction with a period of 2.2 days. To satisfy the moments of inertia, the precession angle must be 77 deg. This model settles the major problems associated with the recent controversy about two rotation periods.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 325; 326-328
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  • 31
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    Geomagnetic equatorial anomaly in zonal plasma flow (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The observation of a geomagnetic signature in the zonal eastward plasma flow, which is a striking feature of the equatorial ionosphere in the evening quadrant is reported. These observations were derived fronm (E x B)/B-squared measurements made with the cylindrical double-floating-probe experiment carried on the Dynamics Explorer 2 satellite. The signature consists of a crest-trough-crest effect in the latitude dependence of the eastward plasma flow with the crests at + or - 8 dip latitude and the trough nearly centered at the dip equator at all geographic longitudes. This phenomenon can be readily interpreted in terms of the altitude dependence of the F region dynamo electric field, and it is related to dip equator signatures in the plasma density and the magnetic declination which have been reported earlier.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 311-315
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  • 32
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    Pioneer 10 and 11 observations of waves upstream of interplanetary corotating shocks (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An extended region of enhanced magnetic field fluctuations is found upstream of some of the corotating shocks observed by Pioneer 10 and Pioneer 11 between 1 and 5 AU. This perturbed region is present when the corotating shock, generally quasi-perpendicular, becomes oblique or quasi-parallel due to a temporary out-of-spiral direction of the upstream magnetic field. The observed waves are almost not compressional. Their amplitude is a large fraction of the ambient field, and their frequency is around 1 mHz in the spacecraft frame. A brief discussion of the possible mechanisms of generation is given.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 285-290
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  • 33
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    Average plasma and magnetic field variations in the distant magnetotail associated with near-earth substorm effects (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 71-81
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    Collisionless coupling in the AMPTE artificial comet (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Analysis of previously reported observations of the solar wind-barium interaction associated with the AMPTE artificial comet release of Dec. 27, 1984, is presented. On the basis of these results it is argued that solar wind couples momentum (and energy) to the barium ions through both laminar and turbulent processes. The laminar forces acting on the particles are the laminar electric and magnetic fields; the turbulent forces are associated with the intense electrostatic wave activity. This wave activity is shown to be caused by a cross-field solar wind proton-barium ion streaming instability. The observed wave frequencies and saturated amplitudes are consistent with the theoretical analysis.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 47-54
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  • 35
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    On the generation of field-aligned plasma flow at the boundary of the plasma sheet (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A possible cause of the large plasma flow velocities parallel to the magnetic field (which were observed in spacecraft experiments) near the boundary of the plasma sheet in the earth's magnetotail is considered in the framework of a magnetohydrodynamic model. It is shown for steady-state configurations that high parallel flow velocities can be expected to exist on field lines connecting to a region of weak magnetic field. The physical mechanism causing large values of the parallel velocity component can be visualized as a strong imbalance of perpendicular mass flux into and out of magnetic flux tubes passing through regions where the magnetic field is weak and inhomogeneous. The value of the parallel velocity component is evaluated, and it is found that it can substantially exceed the perpendicular velocity (by as much as a factor of 40). The results are applied to the earth's magnetotail; it is found that this mechanism is able to explain the parallel flow velocities near the boundary of the plasma sheet in the range of several hundreds of km/s.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 95-107
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  • 36
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    Enhancements of energetic ions associated with travelling compression regions in the deep geomagnetic tail (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: This paper presents a representative example of an enhancement in energetic ion flux associated with the International Sun-Earth Explorer 3 (ISEE 3) spacecraft's encounter with a traveling compression region (TCR). Data from the energetic particle anisotropy spectrometer (EPAS) instrument on ISEE 3 are studied, along with magnetic field data from the vector helium magnetometer. It is concluded that the ion enhancements seen are spatial in nature, thus supporting the idea that TCRs are the lobe signatures of plasmoids moving along the magnetotail, away from earth.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 64-70
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    Ozone reference models for CIRA (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The data bases and computational techniques used in recent models of the O3 distribution in the earth atmosphere are described, summarizing the results of ongoing efforts to define an O3 reference model for incorporation into CIRA. Consideration is given to the analysis of data from satellite instruments (Nimbus 7 LIMS, TOMS, and SBUV; SME UVS and IR; and AE-2 SAGE) to construct models of total column O3 and vertical O3 structure. The satellite-based model predictions are then compared with balloon, rocket, and umkehr measurements in extensive graphs: good agreement is demonstrated both among the satellite data sets and between satellite and nonsatellite data sets.
    Keywords: GEOPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 7; 10, 1
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  • 38
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    Are small diamonds thermodynamically stable in the interstellar medium? (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Very small diamond particles (50 A diameter) are shown to be thermodynamically stable with respect to similar sized graphite particles for reasonable values of the surface free energies of diamond and graphite. Small diamonds are likely to be stable against both thermal evaporation and chemical attack in the general interstellar medium. A few of the consequences of these conclusions are examined.
    Keywords: ASTROPHYSICS
    Type: Astrophysics and Space Science (ISSN 0004-640X); 139; 1, De
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  • 39
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    Effects of El Chichon on stratospheric aerosols late 1982 to early 1984 (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Stratospheric aerosols collected over the western U.S. from late 1982 to early 1984 show the strong effects of El Chichon's eruption. Although mineral particles disappeared during this period, large acid droplets were still common. Because these have never been seen in prevolcanic, background-level collections, they apparently result from increased droplet growth made possible by the unusual abundance of sulfate. Aerosol size distributions show a wide variety of multimodal curves due to mixing of air masses containing aerosols of various ages or histories. Toward the end of the study time there are fewer large aerosols because of gravitational settling and poleward transport. The result is a steady reduction in sulfate, as most aerosol mass is concentrated in a small number of large droplets. Even the later sulfate levels are, however, five times typical prevolcanic background contents. Thus the influence of El Chichon on high-altitude was still considerable 22 months after eruption.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 14761-14
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  • 40
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    The ultraviolet variability of AY Ceti (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: AY Cet is a single-line binary comprised of a spotted G5 III primary and a white dwarf secondary. A series of UV spectra have been obtained with the IUE satellite on five different dates covering a substantial part of the optical cycle of the primary star. No evidence that the continuum or the Ly-alpha absorption line of the secondary star varied is found. There were significant changes in the strengths of the UV emission lines, but the variations were only weakly correlated with either the orbital phase of the binary or the rotational phase of the primary. The UV emission lines were especially strong near maximum visual brightness at a time when the starspot(s) on the primary was least visible. The enhanced line emission is attributed to a flare event on the primary, most likely at a high-latitude site close to the pole of this star. The UV radiative losses of this flare were comparable with those of flares previously observed on the RC CVn variables Lambda And and HR 1099.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 94; 1657-166
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  • 41
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    On the saturation of the refractive index structure function. II - Influence of the correlation length on astronomical 'seeing' (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A physical length scale in the wavefront corresponding to the parameter (r sub 0) characterizing the loss in detail in a long exposure image is identified, and the influence of the correlation scale of turbulence as r sub 0 approaches this scale is shown. Allowing for the effect of 2-point correlations in the fluctuations of the refractive index, Venkatakrishnan and Chatterjee (1987) proposed a modified law for the phase structure function. It is suggested that the departure of the phase structure function from the 5/3 power law for length scales in the wavefront approaching the correlation scale of turbulence may lead to better 'seeing' at longer wavelengths.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 229; 379-382
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  • 42
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    Description of the mean behaviour of ionospheric plasma temperatures (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A status report on the empirical modeling of ionospheric electron and ion temperatures is given with special emphasis on the models used in the International Reference Ionosphere (IRI). Electron temperature models have now reached a state where reliable prediction of the mean altitudinal, latitudinal and diurnal variations is possible. These models are largely based on satellite measurements, but comparisons with incoherent scatter radar measurements have shown excellent agreement. Variations with season and magnetic and solar activity seem to be small and are not yet included consistently in these models. Similar to the electron temperature, the ion temperature shows the largest variations with altitude, latitude and local time. But due to the larger mass, these variations are smoother and more steady in the case of the ions and therefore easier to model. Nevertheless, very few ion temperature models exist. The IRI model takes advantage of the observed concurrence of the ion temperature with the neutral temperature at low altitudes and with the electron temperature at high altitudes.
    Keywords: GEOPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 7; 6, 19
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  • 43
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    Progress in modeling the ionospheric peak and topside electron density (1987)
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    Publication Date: 2011-08-19
    Description: Recent progress made in modeling the electron density profile in the topside ionosphere is reviewed. The results of different F2 peak models are addressed in the light of the data, and the outlook for further progress in this area is discussed. Efforts made toward determining the topside profile shape are reviewed and assessed.
    Keywords: GEOPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 7; 6, 19
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  • 44
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    Plasma instabilities in the terrestrial magnetosphere - A review of recent theoretical research (1987)
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    Publication Date: 2011-08-19
    Description: This paper reviews recent theoretical research on plasma instabilities in the terrestrial magnetosphere. This paper is organized with respect to particle free energies: electron-ion currents, electron beams, ion beams, electron anisotropies and ion anisotropies are successively considered. For each free energy, the associated instability properties are summarized, and their applications to magnetospheric physics are briefly described. Theory and simulations which have established close correlations with observations are emphasized.
    Keywords: GEOPHYSICS
    Type: Physica Scripta (ISSN 0281-1847); T18; 179-187
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  • 45
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    Birkeland currents - Recent contributions from satellite magnetic field measurements (1987)
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    Publication Date: 2011-08-19
    Description: The important role that field-aligned Birkeland currents play in solar terrestrial coupling processes has been known from satellite observations for twenty years. Many satellite have been launched since the last Solar-Terrestrial Symposium with instruments capable of investigating the characteristics of Birkeland currents and their relationship to visible and UV auroral forms, particle precipitation, and convection flow patterns. An important result that has emerged is the close relationship between large-scale Birkeland currents and the orientation of the interplanetary magnetic field. These observations emphasize the fact that Birkeland currents are involved in a wide range of space plasma processes which range from small-scale ionospheric instabilities and irregularities to global scale energy coupling processes between the magnetosphere and solar wind.
    Keywords: GEOPHYSICS
    Type: Physica Scripta (ISSN 0281-1847); T18; 152-157
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  • 46
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    Microturbulence in the upper photosphere of Alpha Persei (F5 Ib) derived from ultraviolet spectral observations (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: High-resolution ultraviolet spectra of the moderate supergiant Alpha Per (F5 Ib) were studied to determine the dynamic state of its upper photosphere. It was found that the line-of-sight microturbulent velocity component in the region of origin of the UV spectrum is about 5 km/s, and is slightly smaller than the value derived from the visual spectrum. This is ascribed to dissipation of mechanical energy between the higher and lower layers where, respectively, the ultraviolet and visual light lines originate. Between these two levels, which are one scale height apart, the mechanical energy flux decreases to about 0.3 of its photospheric value. The consequent value for the (outward directed) turbulent acceleration is 24 cm/sec-squared, more than one half the observationally determined effective acceleration of gravity.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 185; 1-2,
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  • 47
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    Advances in magnetospheric physics by numerical simulations - A critical analysis by an outsider (1987)
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    Publication Date: 2011-08-19
    Description: This is a selective, somewhat editorialized assessment, based on a literature survey, of computer simulation as it exists today in magnetospheric physics. Both large (MHD) and small scale dynamical simulations are described and considered from the perspective of what they are trying to do and with what success. Several specific problem areas where simulations are being carried out are called for commentary: global magnetospheric structure, magnetotail and magnetopause reconnection, Kelvin-Helmholtz instability, hydrodynamic expansion of ionospheric ions, electric double layers, heavy ion heating, and auroral kilometric radiation. It is concluded that simulation is a necessary tool for understanding magnetospheric physics and that significant progress has been made in simulation development. However, results should be evaluated knowing that many factors, some real and physical, others structural, may contribute to such output. A plea is made for greater intercalibration among different simulators working in parallel areas, so that facts can be distinguished from artifacts.
    Keywords: GEOPHYSICS
    Type: Physica Scripta (ISSN 0281-1847); T18; 203-211
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  • 48
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    Deconvolution of a pre-outburst picture of SN 1987A (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The block iterative method (Young 1971) of algebraic image restoration is applied to a photographic plate of the field around SN 1987A obtained 4 yr before outburst by Chu at the CTIO 4-m telescope. By setting appropriate constraints for the solution on a pixel-by-pixel basis, the image of a starfield centered on Sk -69 202, the precursor to the supernova, is restored. It is found that this star has two companions, which others (e.g., Walborn et al., 1987 and West et al., 1987) have also noted and designated as Star 2 and Star 3. Also found is marginal evidence for Star 4, a weak source at theta = 222 deg, r = 1.9 arcsec. Correction for the contributions of these companions yields an estimate of the magnitude for Sk -69 202 alone of V = 12.37.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 185; 1-2,
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    Determination of relative site motions in the western United States using Mark III very long baseline interferometry (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Four years of very long baseline interferometry (VLBI) measurements involving fixed and mobile stations in the western U.S. are analyzed using weighted least squares. Baseline solution time series are used to estimate rates of change of the vector baseline between pairs of VLBI stations. Horizontal vector motions are determined for 18 sites with respect to a site in the Mojave desert. Six sites west of and two sites just to the east of the San Andreas fault show northwestward motion closely parallel to the San Andreas fault. Their motions range from 18 to 43 mm/yr and are significant at confidence levels greater than 99 percent. Motions in California relative to interior North American plate sites are used to estimate an integrated contribution from Basin and Range spreading to the total relative Pacific plate motion as 9-10 mm/yr. A maximum relative velocity of 50-51 mm/yr is found between the interior North American sites and the western California sites, in close agreement with the NUVEL-1 plate motion model.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 12741-12
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    Nonlocal thermodynamic equilibrium effects in stratospheric NO and implications for infrared remote sensing (1987)
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    Publication Date: 2011-08-19
    Description: It is shown that the vibrational state population of stratospheric nitric oxide (NO) could be substantially different from that expected on the basis of LTE. Deviations from LTE may arise because stratospheric NO can be photochemically produced from NO2 with several vibrational quanta. Model calculations suggest that the population of NO(v = 1) could be some 30 percent above that expected from LTE at 30 km, with smaller enhancements above and below. Substantially larger enhancements are predicted for NO(v = 2). This result is shown to have important implications for NO determination by remote sensing of IR emission. Data needed for the quantification of these effects are enumerated.
    Keywords: GEOPHYSICS
    Type: Applied Optics (ISSN 0003-6935); 26; 4747-475
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    Helium diffusion in stars and the value of the cosmological constant (1987)
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    Publication Date: 2011-08-19
    Description: The effect of He diffusion on the evolution of stars is to speed it up by increasing the mean atomic weight at the center, thereby minimizing the apparent conflict between the great ages of globular clusters and the age of the universe, as arrived at via the Hubble constant. Attention is presently given to the consequences of work on this effect by Noerdlinger and Arrigo (1980) and Stringfellow et al. (1983), implying that Tayler's (1986) estimate for globular clusters of 16 Gyr should be reduced to 13 Gyr.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society, Quarterly Journal (ISSN 0035-8738); 28; 345
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    Boreal forests and atmosphere - Biosphere exchange of carbon dioxide (1987)
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    Publication Date: 2011-08-19
    Description: Two approaches to investigating the role of boreal forests in the global carbon cycle are presented. First, a tracer support model which incorporates the normalized-difference vegetation index obtained from advanced, very high resolution radiometer radiances was used to simulate the annual cycle of CO2 in the atmosphere. Results indicate that the seasonal growth of the combined boreal forests of North America and Eurasia accounts for about 50 percent of the mean seasonal CO2 amplitude recorded at Pt. Barrow, Alaska and about 30 percent of the more globally representative CO2 signal at Mauna Loa, Hawaii. Second, tree-ring width data from four boreal treeline sites in northern Canada were positively correlated with Pt. Barrow CO2 drawdown for the period 1971-1982. These results suggest that large-scale changes in the growth of boreal forests may be contributing to the observed increasing trend in CO2 amplitude. They further suggest that tree-ring data may be applicable as indices for CO2 uptake and remote sensing estimates of photosynthetic activity.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 329; 321-323
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    Particle acceleration and production of energetic photons in SN1987A (1987)
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    Publication Date: 2011-08-19
    Description: A pulsar wind model for the acceleration of particles in SN1987A is discussed. The expected photon flux is investigated in terms of the spectrum of parent protons and electrons, the nature of the region in which they propagate after acceleration, and the magnetic field and radiation environment which determines the subsequent fate of produced photons. The model is found to produce observable signals if the spin period of the pulsar is 10 ms or less.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 329; 314-316
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  • 54
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    Observations of jets from low-luminosity stars. II - SVS 12, HH 30, near HL Tauri, and HH 34 (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Spatially resolved spectral scans were obtained for four Herbig-Haro jets emanating from low-luminosity premain-sequence stars. There appears to be a general tendency for the excitation and electron density to diminish along these jets. For three jets, the electron density dependence is close to 1/r. HH 30's scattered stellar continuum showed much weaker Fe II lines in 1985 than in 1979, indicative of variable stellar activity. The most distant knot in HH 34's jet has the lowest excitation of any known HH object, with S II-line/H-alpha = 12.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 321; 846-854
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  • 55
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    Magnetotail equilibrium theory - The general three-dimensional solution (1987)
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    Publication Date: 2011-08-19
    Description: The general magnetostatic equilibrium problem for the geomagnetic tail is reduced to the solution of ordinary differential equations and ordinary integrals. The theory allows the integration of the self-consistent magnetotail equilibrium field from the knowledge of four functions of two space variables: the neutral sheet location, the total pressure, the magnetic field strength, and the z component of the magnetic field at the neutral sheet.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 11101-11
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    Characteristics of wavelike fluctuations in Dynamics Explorer neutral composition data (1987)
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    Publication Date: 2011-08-19
    Description: Wavelike fluctuations in neutral composition data obtained with the neutral atmospheric composition system quadrupole mass spectrometer carried aboard the Dynamics Explorer (DE 2) satellite are at a maximum in the vicinity of the magnetic poles. Typical rms amplitudes near the poles for N2, O, He, and Ar fluctuations in the 400- to 4000-km-wavelength band are found to be 11, 6, 6, and 20 percent, respectively. Amplitudes near the equator are roughly a third of the polar amplitudes, and activity in the 50- to 400-km-wavlength band is roughly 20 percent of the longer-wavelength activity.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 11159-11
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    The unusual radio outburst of Nova Vulpeculae 1984 No. 2 (1987)
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    Publication Date: 2011-08-19
    Description: Multifrequency radio monitoring of Nova Vulpeculae 1984 No. 2 has revealed a unique radio light curve, exhibiting a strong outburst which precedes the appearance of normal radio emission from the principal ejecta of the nova by at least 100 days. The early emission is extremely optically-thick and has brightness temperature in excess of 100,000 K. A model is discussed in which the radiation is produced by a strong shock propagating outward through the principal ejecta of the nova, as a result of an interaction with a later, high velocity wind from the central source. It is shown that the general features of the radio light curve can be explained by the presence of a central wind with a mass loss rate of about 0.00001 solar masses/yr, lasting for a period of 200 to 300 days after the optical outburst. The first radio map of nova ejecta shortly after outburst is presented. Comparison of the angular expansion rate to the ejection velocity implies a distance of 3.6 kpc, and preliminary analysis of the main outburst emission indicates a mass and kinetic energy of the ejecta respectively of about 0.0008 solar masses and 8 x 10 to the 45th erg.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 183; 1, Se
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    Stratospheric trace gases in the spring 1986 Antarctic atmosphere (1987)
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    Publication Date: 2011-08-19
    Description: The atmospheric absorption features of over 500 infrared solar spectra recorded at McMurdo Station have been analyzed to determine the vertical column abundances of trace gases crucial to understanding of the 'ozone hole' phenomenon. The techniques used to retrieve the column abundances are described. Results are reported for ozone, nitrogen species, and halogen sinks and reservoirs.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 329; 126-130
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    Observable properties of E0 triaxial galaxies - A test for triaxiality (1987)
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    Publication Date: 2011-08-19
    Description: It is shown that most triaxial galaxies oriented in space to appear as E0 galaxies should have observable rotation velocities. By projecting Levison and Richstone's (1987) triaxial models so that they look like E0s, it was found that v/sigma can be as large as 1.0. In a separate argument, the observed distribution of axial ratios of ellipticals was used to show that between 3 percent and 23 percent of E0 galaxies are intrinsically flattened systems. Thus, if elliptical galaxies are triaxial then some E0 galaxies should have observable rotation velocities.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 320; L93-L97
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    Polyoxymethylene in Comet Halley (1987)
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    Publication Date: 2011-08-19
    Description: It is shown that polyoxymethylene (POM) with n about four or five explains the mass spectrum obtained with the PICCA instrument during the Giotto encounter with Comet Halley. A sequence of processes is presented showing the likelihood that POM will form under interstellar conditions. A preliminary comet coma model that includes POM is presented which predicts a qualitatively correct spectral intensity behavior when compared with observations.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 320; L149-L15
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    Spectral signatures of jumps and turbulence in interplanetary speed and magnetic field data (1987)
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    Publication Date: 2011-08-19
    Description: It is shown here that, consistent with a suggestion of Burlaga and Mish (1987), the f exp -2 spectra in the magnitudes of the magnetic and velocity fields in the solar wind result from jumps due to various rapid changes in the time series for these quantities. If these jumps are removed from the data, the spectra of the resulting 'difference' time series have the f exp -5/3 form. It is concluded that f exp -2 spectra in these magnitudes arise from phase coherent structures that can be distinguished clearly from incoherent turbulent fluctuations.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 10
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    Light scattering in cometary dust comae (1987)
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    Publication Date: 2011-08-19
    Description: Single and multiple scattering calculations were performed for a spherically symmetric cometary atmosphere irradiated by a plane parallel source. It is suggested that the increased flux found for anisotropic phase functions is due to the effect of directional scattering in the forward sun-comet axis. The isotropic multiply scattered flux at the surface is shown to be an increasing function of the opacity (tau) for tau of less than about 2.5. At large tau values, the maximum in the downward directed scattered flux still increases, but occurs at a height of several radii above the nucleus, resulting in a reduction at the surface. Results suggest that, except in the vicinity of the sun-comet axis, the plane parallel geometry tends to underestimate the degree of scattering.
    Keywords: ASTROPHYSICS
    Type: Earth, Moon, and Planets (ISSN 0167-9295); 39; 51-74
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    Nitric acid forecast experiments (1987)
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    Publication Date: 2011-08-19
    Description: Results of two three-dimensional forecasts of the time evolution of the distribution of HNO3 in the stratosphere are reported. The first is for the February 1979 stratospheric warming, and the second is for a period in March, 1979 when the relative importance of photochemistry and dynamics is thought to be rapidly changing. The zonal mean results of the model calculations are in general qualitative agreement with the LIMS HNO3 observations. However, the calculated three-dimensional fields show significant differences from the observations. The results provide insight into what must be done to form a successful constituent forecast model and provide information on the modeling technique and the self-consistency of the observed dynamical and constituent fields.
    Keywords: GEOPHYSICS
    Type: Physica Scripta (ISSN 0031-8949); 36; 2, Au
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    Infrared spectroscopic measurements of halogenated sink and reservoir gases in the stratosphere with the ATMOS instrument (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument recorded 19 sets of interferograms during solar occultations in both the Northern and Southern Hemispheres over the course of the Spacelab 3 mission. The resulting IR spectra furnish concentration profiles for over 25 atmospheric species. Attention is presently given to the volume mixing ratio profiles for HCl and HF in the 15-60-km altitude region, retrieved from northern sunsets and southern sunrises. The HF/HCl ratios deduced are in good agreement with model predictions. The total atmospheric chlorine at 50 km is nearly all in the form of HCl.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 9851-985
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    On the prolonged lifetime of the El Chichon sulfuric acid aerosol cloud (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The observed decay of the aerosol mixing ratio following the eruption of El Chichon appears to have been 20-30 percent slower than that following the eruption of Fuego in 1974, even though the sulfuric acid droplets were observed to grow to considerably larger sizes after El Chichon. This suggests the possible presence of a condensation nuclei and sulfuric acid vapor source and continued growth phenomena occurring well after the El Chichon eruption. It is proposed that the source of these nuclei and the associated vapor may be derived from annual evaporation and condensation of aerosol in the high polar regions during stratospheric warming events, with subsequent spreading to lower latitudes.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 9825-983
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  • 66
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    Infrared spectroscopic measurements of halogenated source gases in the stratosphere with the ATMOS instrument (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The volume mixing ratios of the six most important halogenated source species (CH3Cl, CF2Cl2, CFCl3, CHF2Cl, CCl4, and CF4) have been retrieved over the 10- to 30-km altitude range from the analysis of 0.01/cm resolution infrared solar occultation spectra recorded near 30 deg N and 47 deg S latitudes with the ATMOS (Atmospheric Trace Molecule Spectroscopy) instrument, operating from on board Spacelab 3 (April-May 1985). The results reported here, although in satisfactory agreement with recent in situ values obtained from air sampling techniques, are limited in accuracy by the limited absorption representative of most of the species and by uncertainties in the spectroscopic parameters currently available for these gases. They demonstrate, however, the power of the IR remote sensing approach for evaluating on a global scale the total chlorine budget of the atmosphere, and they provide an independent set of simultaneous data acquired for the important source and reservoir halogenated molecular species in the upper atmosphere.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 9836-985
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  • 67
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    Count Bowell at record heliocentric distance (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: New observations of Comet Bowell at the record distance of 13.6 AU are presented. An extended coma is present, the size of which is consistent with the same slow expansion rate of roughly 1 m/s detected around perihelion. The cross-section of the solid grains within the central 10 arcsec of the coma has decreased by over an order of magnitude since 1980-84, which indicates that the coma production is declining. The decline began near R of roughly 10 AU, the same distance at which production began on the preperihelion leg. The coma at R of 10 AU or less may be formed by sublimation of CO2 or an ice of similar volatility from the nucleus.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 328; 506-509
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  • 68
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    Formation of large-scale structure from cosmic-string loops and cold dark matter (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Some results from a numerical simulation of the formation of large-scale structure from cosmic-string loops are presented. It is found that even though G x mu is required to be lower than 2 x 10 to the -6th (where mu is the mass per unit length of the string) to give a low enough autocorrelation amplitude, there is excessive power on smaller scales, so that galaxies would be more dense than observed. The large-scale structure does not include a filamentary or connected appearance and shares with more conventional models based on Gaussian perturbations the lack of cluster-cluster correlation at the mean cluster separation scale as well as excessively small bulk velocities at these scales.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 328; 691-694
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  • 69
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    Orbital eccentricity in classical novae (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The effect on the orbital parameters of a classical nova of the ejection of mass during the nova explosion is considered. The most easily observable consequence is the generation of a small eccentricity in the orbit which leads to a luminosity modulation at a period just longer than the orbital period. Observation of such an effect would have implications not just for interpreting the dynamics of the explosion but also for measuring the secular effect of tidal interaction after the outburst.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 328; 505
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  • 70
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    Regularly pulsed neutrinos from supernova SN1987A? (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Some consequences of the 8.9 millisecond periodicity observed in neutrino events from SN1987A with the Kamiokonde and IMB experiments are discussed. Interpreting the apparent period as a rotation of a compact object would imply that the neutrino emission is anisotropic and that the neutrino mass, averaged over all observed flavors, is less than 0.2 eV/c-squared. It is also noted that P = 8.9 ms is a reasonable period for very young pulsars.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 328; 503
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  • 71
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    Observed beaming of terrestrial myriametric radiation (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Observations by the Dynamics Explorer 1 satellite are discussed which validate the theory that terrestrial myriametric radiation (TMR) is produced by the linear conversion of electrostatic upper hybrid waves to electromagnetic radiation via a radio window. A remote sensing technique based on the theory is used to investigate the location and characteristics of the source region. Finally, the location of the TMR source region is demonstrated by direct measurement.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 328; 391-395
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  • 72
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    Nonspherical supernova remnants. IV - Sequential explosions in OB associations (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Multisupernova remnants, driven by sequential supernova explosions in OB associations, are modelled by means of two-dimensional hydrodynamical calculations. It is shown that due to the Rayleigh-Taylor instability the remnants quickly evolve into highly irregular structures. A critical evaluation of the multisupernova model as an explanation for supershells is given.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 182; 1, Au; 120-126
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  • 73
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    Evolutionary sequences for horizontal branch stars (1987)
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    Publication Date: 2011-08-19
    Description: A new grid of canonical evolutionary horizontal branch (HB) sequences is presented. Sequences are computed for each combination of the following helium and heavy-element abundances, respectively: Y(main sequence) = 0.20, 0.25, 0.30, and Z = 0.0001, 0.001, and 0.01. The results show that the bifurcation point at which the HB morphology changes from redward-evolving tracks to tracks with blueward loops shifts to higher effective temperatures with increasing helium abundance or metallicity. The sequences can be used to study in more detail how a number of HB properties such as the HB lifetime, the effective temperature at the bifurcation point in the track morphology, the luminosity dropoff of the blue HB, and the luminosity width of the red HB depend on the composition.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal Supplement Series (ISSN 0067-0049); 65; 95-135
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  • 74
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    Ice measurements by Geosat radar altimetry (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Radar altimetry for ice-covered ocean and land is more complex and variable than open ocean radar altimetry; attention is presently given to Geosat ice-sheet topography for the Greenland and Antarctic ice sheets between 72 deg N and 72 deg S which owes its excellent accuracy to the well separated spacing of the orbital tracks and an 18-month geodetic mission duration. A surface elevation map of southern Greenland, produced from 110 days of retracked Geosat data, is presented in color-coded three-dimensional perspective. Comparisons are made between Seasat and Geosat data for ice mass elevations in Greenland.
    Keywords: GEOPHYSICS
    Type: Johns Hopkins APL Technical Digest (ISSN 0270-5214); 8; 251-254
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    Shock processing of interstellar dust - Diamonds in the sky (1987)
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    Publication Date: 2011-08-19
    Description: The processing of interstellar dust grains by strong shock waves is studied, with the emphasis on the effects of grain-grain collisions. Such collisions provide the high pressures required to transform interstellar graphite and amorphous carbon grains into diamonds. Diamond metamorphism is as important for the destruction of such grains as vaporization and sputtering. It is calculated that about 5 percent of the C is expected to be in the form of 5-100 A diamonds in the interstellar medium. These results support the suggested interstellar origin for the recently discovered small meteoritic diamonds by providing a feasible interstellar formation mechanism.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 319; L109-L11
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    Quantized synchrotron radiation in strong magnetic fields (1987)
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    Publication Date: 2011-08-19
    Description: Spectra from electrons making synchrotron transitions in high magnetic fields are calculated using the exact quantum transition rates for Landau states up to n = 500, and the results are compared with spectra calculated from the classical formula and the asymptotic quantum formula. The behavior of the transition rates are examined at low and high harmonics as a function of the spin state of the electron. The calculations confirm those of Herold, Ruder, and Wunner (1982) for low Landau states, extending them to higher states and individual spin state transitions. The results also confirm the dominance of ground-state transitions at high field strengths noted by White (1976). Single particle emissivities for electrons with both spin-up and spin-down in the initial state are calculated using these transition rates. Spectra for thermal electron distributions at transrelativistic temperatures and for steady state injection of monoenergetic electrons with isotropic pitch angles are also presented.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 319; 939-950
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    Molecular and atomic clouds associated with infrared cirrus in Ursa Major (1987)
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    Publication Date: 2011-08-19
    Description: Observations of CO and H I revealed that in Ursa Major the high-latitude far-infrared 'cirrus' emission discovered by the Infrared Astronomical Satellite comes from molecular and atomic clouds. These clouds differ sufficiently from the large clouds in the Galactic plane so that the ratio of H2 column density to velocity-integrated CO radiation temperature, N(H2)/W(CO), derived from Galactic plane surveys, may not apply to them. On the assumption of a constant gas-to-dust ratio, it is argued that the cirrus emission in Ursa Major is a good mass tracer, since both the atomic and the molecular gas are probably optically thin at visual wavelengths, and the grains are heated not by local sources but by the background field of Galactic starlight. The N(H2)/W(CO) ratio thus derived for those diffuse clouds, is significantly lower than the ratio applicable to Galactic plane surveys.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 319; 723-729
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    Snow load effect on earth's rotation and gravitational field, 1979-1985 (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A global, monthly snow depth data set has been generated from the Nimbus 7 satellite observations using passive microwave remote-sensing techniques. Seven years of data, 1979-1985, are analyzed to compute the snow load effects on the earth's rotation and low-degree zonal gravitational field. The resultant time series show dominant seasonal cycles. The annual peak-to-peak variation in J2 is found to be 2.3 x 10 to the -10th, that in J3 to be 1.1 x 10 to the -10th, and believed to decrease rapidly for higher degrees. The corresponding change in the length of day is 41 micro-s. The annual wobble excitation is (4.9 marc sec, -109 deg) for the prograde motion component and (4.8 marc sec, -28 deg) for the retrograde motion component. The excitation power of the Chandler wobble due to the snow load is estimated to be about 25 dB less than the power needed to maintain the observed Chandler wobble.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 9415-942
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    Lava flows as kinematic waves (1987)
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    Publication Date: 2011-08-19
    Description: A recently proposed model for the emplacement of lava flows is reinterpreted as a kinematic wave theory for the depth of the flow. Explicit kinematic wave solutions and their properties are derived for three time-dependent boundary conditions of practical interest. These boundary conditions correspond to effusion rates that decrease, increase, and crest and broadly reflect types of eruption behavior documented in the geologic literature. Particular attention is given to the way source behavior propagates along the flow in relation to the advance of the flow itself.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 9271-927
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    Beat relationships between orbital periodicities in insolation theory (1987)
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    Publication Date: 2011-08-19
    Description: Variations in insolation are examined in terms of beat relationships. The relations between eccentricity periods, precessional parameters, and obliquity periods are analyzed. Beat periods are calculated and compared with orbital periodicities from Berger's (1978) series expansions. It is noted that the data, which correlate eccentricity, obliquity, and precessional-parameter periods, are applicable to the study of orbital periodicities in time-series analyses of long-term climatic records.
    Keywords: GEOPHYSICS
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 44; 1875
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    Plasma transport in the auroral return current region (1987)
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    Publication Date: 2011-08-19
    Description: The classical and anomalous transport properties of a multifluid plasma consisting of H(+), O(+), and electron populations in the presence of auroral field-aligned return currents are investigated, using a multimoment fluid model with anomalous transport coefficients. The macroscopic effects of the electrostatic ion cyclotron (EIC) instability and of an EIC-related anomalous resistivity mechanism which heats the electrons are included in the present version of the model. The responses of the outflowing polar wind plasma to the application of current, with and without instabilities, are exhibited. The simulations show that the electron drift velocity corresponding to a return current of 0.65 micro-A/sq m is above the threshold for EIC waves. Downward electron heat flow competes with upward convection and adiabatic effects to determine the direction of the electron temperature anisotropy. Resistive electron heating lowers the critical drift velocity for marginal EIC stability and leads to enhanced ion heating.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 8673-869
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    Numerical simulation of the generation of turbulence from cometary ion pick-up (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Observations of magnetic field fluctuations near Comet Halley have revealed a rapid development of a Kolmogoroff-like turbulence spectrum extending from below 0.01 Hz to above 0.1 Hz. Spectra obtained far from the comet have a strong peak in power near the Doppler-shifted ion-cyclotron frequency of singly ionized water. Closer to the comet, the spectrum at higher frequencies is enhanced in power level over the background solar wind spectrum by approximately an order of magnitude. The equations of incompressible MHD are solved using a two-dimensional 256 x 256 mode spectral method code to simulate this spectral evolution as an inertial range turbulent cascade. The initial conditions contained a constant magnetic field and a single coherent wave mode at a low wave number. The solar wind turbulence was modeled by a background noise spectrum having a Kolmogoroff spectral index. The coherent mode decayed into an inertial range spectrum with Kolmogoroff slope within a few eddy-turnover times. Both the time scale and the increase in power level of the turbulence seen in the simulation are in accord with the Giotto observations.
    Keywords: ASTROPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 14; 860-863
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    The solar wind-magnetosphere-ionosphere current-voltage relationship (1987)
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    Publication Date: 2011-08-19
    Description: The global current-voltage relationship for the solar wind-magnetosphere-ionosphere system (SW-M-I) is investigated, restricting the study to strong southward IMF. The dynamo presently identified is on open field lines, and it operates at close to short circuit and at a fraction of the available power output. Control of the dynamo by ionospheric conductivity is discussed. Implications of the simulation results, including the relationship between open and closed field dynamos, the effect of solar wind conditions, the control of reconnection on the bow, the size of the open field line region, and the effects of increased auroral conductivity, are discussed.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 14; 880-883
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    IRAS observations of southern molecular clouds (1987)
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    Publication Date: 2011-08-19
    Description: A report is given of a project to use IRAS Band 3 (60 microns) and Band 4 (100 microns) observations to investigate the far-infrared properties of southern galactic molecular clouds. A method by which dust temperature and total gas column density can be estimated is presented. Results are tabulated for 65 prominent southern far-infrared sources. The dust temperatures are closely grouped between 30 and 50 K, while the column densities range between 2 x 10 to the 20th and 10 to the 22nd/sq cm. Maps of dust temperature and gas column density have been generated for two fields containing far-infrared sources to illustrate the effectiveness of this form of presentation.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 227; 1013-102
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    X-ray spectra and atmospheric structures of bursting neutron stars (1987)
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    Publication Date: 2011-08-19
    Description: Atmospheric structures and emitted X-ray spectra of bursting neutron stars are investigated. Theoretical curves are fitted to observational ones on the color temperature vs. luminosity diagram and two relations among mass, radius, and distance of the bursters are obtained. The fit of the theoretical curve to observations is statistically acceptable. Two possible sets of mass, radius, and distance to the X-ray bursts source MXB 1636-536 are derived, taking into account absorption lines at 4.1 keV, theoretical mass-radius relations of neutron star models, and the distance to the Galactic center. If the absorption line is due to Cr XX III, then M = 1.7-2.0 solar masses, R = 11-12 km, and d = 6.3-6.7 kpc, and if it is due to Fe XXV, then M = 1.8-2.1 solar masses, R = 8-10 km, and d = 5.8-6,4 kpc. The distance to the Galactic center is almost the same as that to MXB 1636-536.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of Japan, Publications (ISSN 0004-6264); 39; 2, 19; 287-308
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    Aerosol optical depth and planetary Albedo in the visible from the Solar Mesosphere Explorer (1987)
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    Publication Date: 2011-08-19
    Description: The Solar Mesosphere Explorer (SME) satellite has observed the visible sunlight scattered at the earth's limb since early 1982. By using a radiative-transfer model including multiple scattering and albedo effects, observations at 20 deg N latitude have been interpreted in terms of aerosol optical depth. The ratio of aerosol extinction to Rayleigh extinction at 431.8 nm shows a large increase after the eruption of El Chichon. A maximum ratio of 5 at 36 km and larger than 11 at 30 km occurred in the summer of 1982 followed by a decrease through 1983 and 1984. Aspects of the aerosol time evolution appear to be consistent with other observations and model predictions. Quantitative differences exist between inferred SME and lidar extinction coefficients, possibly due to the different wavelengths of the measurements and to the different scattering phase functions used in the two analyses. It is also shown that visible limb radiances provide information on the planetary albedo, which shows an increase from the equator to the poles with a maximum in the winter hemisphere and a minimum in the summer hemisphere.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 8373-838
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    Optical and UV spectroscopy of the black hole binary candidate LMC X-1 (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Both further optical spectroscopy of the binary star identified with LMC X-1, obtained between 1983 and 1985, and a series of IUE UV spectra taken during a 5 day interval in 1984 are presented. The optical data are used to refine the orbital period to 4.2288 days, and improved orbital parameters are derived. The velocity of the optical emission lines is antiphased with the absorption lines and has twice the velocity amplitude. These new results support the estimates of the masses in the system given earlier. The most probable component masses are approximately 20 solar masses for the primary and near 6 solar masses (for the x-ray star), suggesting the the latter may be a black hole. The UV spectra show very weak, low-velocity stellar-wind lines. It is suggested that much of the surrounding medium is highly ionized by the X-ray flux. The 'nonwind' UV spectral lines and the UV continuum temperature are consistent with the optical data, indicating a late O type star of M(bol) = -8.5. There is a weak modulation of absorption-line strengths with orbital phase, suggestive of a lack of axisymmetry in the X-irradiation of the primary star and indicative of a fairly low orbital inclination.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 94; 340-344
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    The hydrogen coverage of interstellar PAHs (1987)
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    Publication Date: 2011-08-19
    Description: The rate at which the CH bond in interstellar Polycyclic Aromatic Hydrocarbons (PAHs) rupture due to the absorption of a UV photon has been calculated. The results show that small PAHs (less than or equal to 25 carbon atoms) are expected to be partially dehydrogenated in regions with intense UV fields, while large PAHs (greater than or equal to 25 atoms) are expected to be completely hydrogenated in those regions. Because estimate of the carbon content of interstellar PAHs lie in the range of 20 to 25 carbon atoms, dehydrogenation is probably not very important. Because of the absence of other emission features besides the 11.3 micrometer feature in ground-based 8 to 13 micrometer spectra, it has been suggested that interstellar PAHs are partially dehydrogenated. However, IRAS 8 to 22 micrometer spectra of most sources that show strong 7.7 and 11.2 micrometer emission features also show a plateau of emission extending from about 11.3 to 14 micrometer. Like the 11.3 micrometer feature, this new feature is attributed to the CH out of plane bending mode in PAHs. This new feature shows that interstellar PAHs are not as dehydrogenated as estimated from ground-based 8 to 13 micrometer spectra. It also constrains the molecular structure of interstellar PAHs. In particular, it seems that very condensed PAHs, such as coronene and circumcoronene, dominate the interstellar PAH mixture as expected from stability arguments.
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    Photometric light curves for seven rapidly-rotating K dwarfs in the Pleiades and Alpha Persei clusters (1987)
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    Publication Date: 2011-08-19
    Description: Light curves and period estimates were obtained for several Pleiades and Alpha Persei cluster K dwarfs which were identified as rapid rotators in earlier spectroscopic studies. A few of the stars have previously-published light curves, making it possible to study the long-term variability of the light-curve shapes. The general cause of the photometric variability observed for these stars is an asymmetric distribution of photospheric inhomogeneities (starspots). The presence of these inhomogeneities combined with the rotation of the star lead to the light curves observed. The photometric periods derived are thus identified with the rotation period of the star, making it possible to estimate equatorial rotational velocities for these K dwarfs. These data are of particular importance because the clusters are sufficiently young that stars of this mass should have just arrived on the main sequence. These data could be used to estimate the temperatures and sizes of the spot groups necessary to produce the observed light curves for these stars.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of the Pacific, Publications (ISSN 0004-6280); 99; 471-481
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    An equivalent layer magnetization model for Australia based on Magsat data (1987)
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    Publication Date: 2011-08-19
    Description: An equivalent layer magnetization model for Australia and adjacent oceanic areas is presented. The model is obtained by linear inversion of Magsat anomaly data measured in the altitude range 325-550 km. The anomaly data set has been isolated from the raw data set by use of models of the core field and very long wavelength external fields, and is internally consistent. Certain major structural features of the Australian continent are geographically associated with magnetization anomalies. A first-order difference is seen between the Tasman Zone and the Precambrian cratonic areas: magnetization anomalies are much more subdued in the former, possibly reflecting a shallowing of the Curie isotherm within the crust. A profile of the vertical integral of magnetization is presented for a crustal section extending from the Gawler Block to the southeast coast. It is shown that the magnetization variations are probably due partly, but not wholly, to depth to Curie isotherm variations; gross magnetization variations among at least three distinct crustal units must be involved.
    Keywords: GEOPHYSICS
    Type: Earth and Planetary Science Letters (ISSN 0012-821X); 83; 1-4,; 167-174
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  • 91
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    Modeling the Milky Way in the infrared (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The spatial distribution of stars in the Milky Way is modeled using an exponential disk with the addition of a de Vaucouleurs (1958, 1977, and 1979) R exp 1/4 spheroid. The present model is compared to 2-2.5-micron star counts and surface-brightness data and to IRAS 12-micron source counts. The data are consistent with a flattened bulge; it is maintained that a fraction of the bulge population has a considerable infrared excess.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of the Pacific, Publications (ISSN 0004-6280); 99; 453-460
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  • 92
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    Global excitation of wave phenomena in a dissipative multiconstituent medium. III - Response characteristics for different sources in the earth's thermosphere (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A linear trasnfer function model of the earth's thermosphere which includes the electric field momentum source is used to study the differences in the response characteristics for Joule heating and momentum coupling in the thermosphere. It is found that, for Joule/particle heating, the temperature and density perturbations contain a relatively large trapped component which has the property of a low-pass filter, with slow decay after the source is turned off. The decay time is sensitive to the altitude of energy deposition and is significantly reduced as the source peak moves from 125 to 150 km. For electric field momentum coupling, the trapped components in the temperature and density perturbations are relatively small. In the curl field of the velocity, however, the trapped component dominates, but compared with the temperature and density its decay time is much shorter. Outside the source region the form of excitation is of secondary importance for the generation of the various propagating gravity wave modes.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 7657-767
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  • 93
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    Atmospheric odd oxygen production due to the photodissociation of ordinary and isotopic molecular oxygen (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Line-by-line calculations are performed to determine the contributions of the Schumann-Runge bands of ordinary and isotopic oxygen to the photodissociation of these molecules at different altitudes. The contributions to the dissociation rates of the satellite lines and of the first and higher vibrational states of the initial molecular states are found to be insignificant. At 70 km, (O-16)(O-18) is found to produce 10 times as much odd oxygen as would be produced if the isotope did not have selective absorption, and 6 percent of the odd oxygen produced is due to this isotope. It is noted that the excess odd oxygen produced is not enough to explain the excess quantity of ozone observed in the atmosphere, which cannot be accounted for in photochemical models. Comparison with previous results is made.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science (ISSN 0032-0633); 35; 769-784
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  • 94
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    Behavior of ionized plasma in the high latitude topside ionosphere - The polar wind (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A numerical model is used to investigate the steady-state behavior of a fully ionized plasma encompassing the geomagnetic field lines from 1500 km to 10 earth radii, and solutions of the 16 moment system of transport equations for the polar wind are obtained. For the present cases studied, results of the 13 and 16 moment simulations are found to be similar, although the temperature anisotropy is quite high. Polar wind studies reveal an electron temperature anisotropy developing around 2500 km, with the collisions keeping the electron temperature isotropic below 2500 km. Good agreement is found between the present polar wind simulations and recent observations.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science (ISSN 0032-0633); 35; 703-714
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  • 95
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    Evolutionary models of interstellar chemistry (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The goal of evolutionary models of interstellar chemistry is to understand how interstellar clouds came to be the way they are, how they will change with time, and to place them in an evolutionary sequence with other celestial objects such as stars. An improved Mark II version of an earlier model of chemistry in dynamically evolving clouds is presented. The Mark II model suggests that the conventional elemental C/O ratio less than one can explain the observed abundances of CI and the nondetection of O2 in dense clouds. Coupled chemical-dynamical models seem to have the potential to generate many observable discriminators of the evolutionary tracks. This is exciting, because, in general, purely dynamical models do not yield enough verifiable discriminators of the predicted tracks.
    Keywords: ASTROPHYSICS
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  • 96
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    Optical observations related to the molecular chemistry in diffuse interstellar clouds (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Observations, which have been published since 1979, of molecular species in diffuse clouds are discussed. Particular attention is given to the ultraviolet measurements of CO with the Copernicus and IUE satellites and to ground-based optical measurements of CH, CH(+), CN, and 02. These data encompass large enough samples to test the chemical schemes expected to occur in diffuse clouds. Upper limits for other species (e.g., H2O, H2O(+), and C3) place restrictions on the pathways for molecular production. Moreover, analysis of the rotational distribution of the C2 molecule results in the determination of the physical conditions of the cloud. These parameters, including density, temperature, and the intensity of the radiation field, are necessary for modeling the chemistry.
    Keywords: ASTROPHYSICS
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  • 97
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    The fate of the earth in the red giant envelope of the sun (1987)
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    Publication Date: 2011-08-19
    Description: The effect on the earth of entering the red giant envelope of the future sun is studied. Employing a 30-zone red giant model, the earth orbital decay timescale, neglecting ablation/vaporization, is determined to be of the order of 200 years, rendering earth survival impossible. The effects of ablation/vaporization processes are found to increase the ballistic coefficient of earth, thereby setting the 200-year decay timescale as an upper limit.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 178; 1-2,
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  • 98
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    Thermal diffusion in partially ionized gases - The case of unequal temperatures (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Previous calculations of thermal diffusion coefficients in partially ionized gases are extended to the case of unequal neutral and ion temperatures and/or temperature gradients. Formulas are derived for the general case of a major gas as well as for minor atoms and ions. Strong enhancements of minor-ion thermal diffusion coefficients over their values in the fully ionized gas are found when the degree of ionization in the main gas is relatively low. However, compared to the case of equal temperatures, the enhancements are less strong when the neutrals are cooler than the ions. The specific case of the H-H(+) mixture, which is important in the study of solar and stellar atmospheres, is discussed as an application.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 178; 1-2,; 286-291
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  • 99
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    A search for sinusoidal gravitational radiation in the period range 30-2000 seconds (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Since condensed massive objects in binary systems should generate observable periodic gravitational radiation, a large fraction of which may appear in one harmonic of the orbital frequency, monochromatic Doppler frequency perturbations were searched for at about 9000 discrete frequencies in the 0.0005-0.0333-Hz band using predetection data taken with the Pioneer 11 spacecraft. The results of the search are presented, and formal sensitivities for the possible signals are discussed. The results are interpreted as observational thresholds for possible incident gravitational wave trains having polarization states and propagation directions that are a priori unknown.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 318; 536-541
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  • 100
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    Crustal geologic studies with Magsat and surface magnetic data (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The contributions during the last quadrennium are discussed, which involved both Magsat and aeromagnetic data, including new techniques for interpreting this data, specific intended to understand the connection between magnetic anomalies and the magnetic mineralogy of their sources.
    Keywords: GEOPHYSICS
    Type: Reviews of Geophysics (ISSN 8755-1209); 25; 971-981
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