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  • LUNAR AND PLANETARY EXPLORATION  (1,410)
  • Inorganic Chemistry  (1,364)
  • GEOPHYSICS  (1,228)
  • 1985-1989  (2,026)
  • 1980-1984  (1,976)
  • 1987  (2,026)
  • 1982  (1,976)
Collection
Keywords
Publisher
Years
  • 1985-1989  (2,026)
  • 1980-1984  (1,976)
Year
  • 1
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    Planetary atmospheres (1987)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Present understanding of planetary atmospheres is surveyed. The formation of the planets and their atmospheres is briefly reviewed, and attention is given to the compositions of the atmospheres of earth, Venus, and Mars, the outer planets, and Titan. Lists of the individual atmospheric gases and their concentrations are included.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 2
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    Vehicle design for Mars surface exploration (1987)
    In:  CASI
    Details
    Publication Date: 2004-12-04
    Description: This design course is directed to studying problems related to mobile exploration of the surface of Mars. Constraints on the vehicles considered are set by the payload and performance currently envisioned by mission analysis carried out previously at the Jet Propulsion Laboratory. The students are given full flexibility to examine those aspects which suit their interests and background. There are no regularly scheduled class lectures. Weekly review meetings are held with personnel from the Jet Propulsion Laboratory, and students use JPL resources as required.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: USRA, Agenda of the Third Annual Summer Conference, NASA(USRA University Advanced Design Program; p 11
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  • 3
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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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  • 4
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    High-resolution lunar radar map at 70-cm wavelength (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: New radar observations of the moon in 1981-1984 were made using the 430 MHz (70 cm wavelength) radar at the Arecibo observatory, Puerto Rico. The new observations have produced a high resolution lunar radar map with radar cell-sizes near 2-5 km. This new resolution is a three-fold improvement over the previous mapping done in the late 1960's. Since the Arecibo radar antenna beam is only ten arc-minutes (about one-third of the width of the lunar disk), this new map is a mosaic of some eighteen observations. A radarmetric control between the various pieces of the mosaic was obtained via a 'beam-swing', limb-to-limb calibration. When the limb-to-limb calibration was combined with the mosaic, there were significant radar scattering differences across the maria. Eastern Mare Tranquillitatis and western Oceanus Procellarum have weaker echoes than other maria, while the central portion of Mare Serenitatis and northern Mare Imbrium have stronger echoes. There is a radar scattering difference across the southern terra as areas nearer Mare Orientale have stronger echoes than areas further from Mare Orientale.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth, Moon, and Planets (ISSN 0167-9295); 37; 59-70
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  • 5
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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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  • 6
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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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  • 7
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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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  • 8
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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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  • 9
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    The ionotail of Venus - Its configuration and evidence for ion escape (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The configuration and morphology of the plasma clouds in the ionotail of Venus (revealed by the Pioneer Venus Orbiter) are studied, and the rate of planetary ion escape, which may be associated with the dissipation and removal of the ionospheric plasma, is estimated. The data supplied by the Orbiter's instruments, the Orbiter electron temperature probe, the ion mass spectrometer, the neutral mass spectrometer, the magnetometer, and the plasma analyzer, are analyzed, and the results of the observations are discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 15-26
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  • 10
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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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  • 11
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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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  • 12
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    Further information on structure of the atmosphere of Venus derived from the Vega Venus balloon and lander mission (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Continued analysis of the pressure and temperature data returned by the two Vega mission balloons has revealed an apparently significant difference in mean atmospheric static stability between the two data sets. Furthermore, the stability is time dependent within each data set. The 6.5 K temperature contrast between the two balloons remains, and appears to have a counterpart in the contrast between two of the Pioneer Venus probes at these levels, which has been attributed to planetary scale waves. Comparisons of the Vega 2 lander data with those of the Pioneer Venus Large Probe shows relatively close agreement in the state properties and in the atmospheric static stability profiles as well.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Advances in Space Research (ISSN 0273-1177); 7; 12, 1; 323-328
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  • 13
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    Meteorological variations in the middle clouds of Venus from Vega balloon in situ measurements (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Instruments aboard the gondolas of the two Vega balloons obtained in situ measurements of pressure, temperature, vertical velocity relative to the balloon, cloud particle backscatter, lightning and the ambient light level. Atmospheric motions at the balloon float altitudes were also determined from earth-based tracking results. To illustrate the history of the balloon flights and to facilitate comparisons between some of the different observed quantities, measurements of pressure, temperature and backscatter are presented as time series for the entire lifetime of each balloon. Both long and short period variations have been detected. In addition, the environmental entropy encountered by each balloon will be discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Advances in Space Research (ISSN 0273-1177); 7; 12, 1
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  • 14
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    Results of the Vega 1 balloon nephelometer experiment (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Backscatter nephelometer measurements obtained during the Vega 1 balloon flight are reported. During periods of minor convective activity and initial balloon ascent, the data generally agree with those obtained from other Venus mission descent probes. However, during the period of greatest convective activity experienced by the Vega 1 balloon, the signals were about a factor of two greater than any previously obtained. Although the clouds appear to be unbroken, deviations in the behavior of the detailed backscatter signals with time from those of the ambient pressure or temperature signals, especially during periods of minor convective activity, indicate much small-scale variability in cloud structure.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Advances in Space Research (ISSN 0273-1177); 7; 12, 1
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  • 15
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    Implications of the Vega balloon results for Venus atmospheric dynamics (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: During the Vega Venus balloon mission, data on the thermodynamic state of the atmosphere were obtained as well as wind and cloud information. Explanations are provided for the following: (1) the large amplitude atmospheric vertical winds encountered by the Vega balloons, (2) the observed 6.5 K temperature difference consistently measured between the two Vega balloons, and (3) the apparent influence of surface topography on atmospheric motions seen by the Vega-2 balloon as it flew over mountainous terrain (known as Aphrodite). It is believed that vertical winds of the magnitude encountered by the Vega-2 balloon over Aphrodite may be the result of surface-induced gravity waves.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Advances in Space Research (ISSN 0273-1177); 7; 12, 1
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  • 16
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    Initial estimates of Venus winds from ground-based radio tracking of the Vega balloons (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A global array of 20 radio observatories was used to measure the three-dimensional position and velocity of the two meteorological balloons that were injected into the equatorial region of the Venus atmosphere by the Vega spacecraft. Initial analysis of only radial velocities indicates that each balloon was blown westward about 11,500 kilometers (8000 kilometers on the night side) by zonal winds with a mean speed of about 70 meters per second. Excursions of the data from a model of constant zonal velocity are generally less than 3-meters per second; however, a much larger variation is evident near the end of the flight of the second balloon. Consistent systematic trends in the residual for both balloons indicate the possibility of a solar-fixed atmospheric feature.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Advances in Space Research (ISSN 0273-1177); 7; 12, 1
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  • 17
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    Voyager 2 plasma wave observations at Uranus (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: At Uranus, the Voyager 2 plasma wave investigation observed very significant phenomena related to radio emissions, dust impacts, and magnetospheric wave-particle interactions. On January 19, 1986 (R = 270 R-sub U) the plasma wave investigation detected an intense radio burst at 31 and 56 kHz, and this provided the first indication that Uranus had a magnetosphere. During the encounter, more of these sporadic bursts were observed along with relatively continuous radio emissions extending down to 10 kHz, and a sporadic narrowband radio signal with f near 5 kHz. As Voyager passed through the ring plane, the plasma wave investigation recorded a large number of dust impacts. The Voyager 2 plasma wave instrument also detected many strong electromagnetic and electrostatic plasma waves, with intensity peaks in the region within 12 Uranus radii. These waves have characteristics that can interact strongly with the local plasma and with the trapped energetic particles, leading to precipitation into the atmosphere, charged particle acceleration, and charged particle diffusion. In addition, strong wave activity was detected in the region of the bow and shock and moderate levels in the magnetic tail.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Advances in Space Research (ISSN 0273-1177); 7; 12, 1
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  • 18
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    Radio emissions from Uranus (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The hardware of the Planetary Radio Astronomy Experiment aboard Voyager 2 and the results of the measurements of radio emissions from Uranus are described. Strong 40-kHz to 850-kHz radio emissions were detected after closest approach on the day-side of Uranus. The time variations of these emissions were periodic, with a period of 17.24 h closely matching that of Uranus's rotation and evidently being controlled by the strength and shape of its magnetic field. The instrument also recorded possible Uranian electrostatic discharges, vertex early arcs occurring in sequences of more than a dozen events with approximately 10-min period, and very intense isolated bursts lasting tens of minutes.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Advances in Space Research (ISSN 0273-1177); 7; 12, 1; 243-251
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  • 19
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    Current review of the Jupiter, Saturn, and Uranus ionospheres (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The ionospheres of the major planets Jupiter, Saturn, and Uranus are reviewed in light of Pioneer and Voyager observations. Some refinements to pre-Voyager theoretical models are required to explain the results, most notably the addition of significant particle ionization from 'electroglow' and auroral processes and the need for additional chemical loss of protons via charge exchange reactions with water. Water from the Saturn rings has been identified as a major modifier of the Saturn ionosphere and water influx from satellites and/or meteorites may also be important at Jupiter and Uranus as well, as evidenced by the observed ionospheric structure and the identification of cold stratospheric carbon monoxide at Jupiter.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Advances in Space Research (ISSN 0273-1177); 7; 12, 1
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  • 20
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    Neutral upper atmospheres of Venus and Mars (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Results obtained over the last 21 years from satellite measurements of the neutral upper atmospheres of Venus and Mars are discussed. Particular attention is given to the chemistry of the neutral upper atmospheres of the two planets, the exospheric temperatures, and the sensitivity of their atmospheric temperatures to solar activity. Various theoretical models used to interpret the planetary atmospheric data are discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Advances in Space Research (ISSN 0273-1177); 7; 12, 1
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  • 21
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    Neutral upper atmospheres of the outer planets (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The major characteristics of the neutral upper atmospheres of outer planets are discussed, with special attention given to the Uranus upper atmosphere, probed by Voyager 2. The composition, thermal structure, photochemistry, and vertical mixing of the Uranus atmosphere are compared with the respective features of other outer planets. Unlike the atmospheres of Jupiter and Saturn, which reflect the solar ratios of the elements, the Uranus atmosphere was found to have only few constituents, including NH3, CH4, H2, He, C2H2, and C2H6. The eddy diffusion coefficient of Uranus, determined from occultation experiments, was found to be in the range 10,000-100,000 sq cm/sec, the lowest value amongst the major planets; this implies relatively sluggish vertical mixing. Another major difference from Saturn and Jupiter is in the fact that stable hydrocarbon products (C2H2 and C2H6) in the Uranus atmosphere begin to condense at around 5-10 mb level, resulting in the production of haze in the lower stratosphere.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Advances in Space Research (ISSN 0273-1177); 7; 12, 1; 79-85
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  • 22
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    Past and future of radio occultation studies of planetary atmospheres (1987)
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    Publication Date: 2011-08-19
    Description: Measurements of radio waves that have propagated through planetary atmospheres have provided exploratory results on atmospheric constituents, structure, dynamics, and ionization for Venus, Mars, Titan, Jupiter, Saturn, and Uranus. Highlights of past results are reviewed in order to define and illustrate the potential of occultation and related radio studies in future planetary missions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Advances in Space Research (ISSN 0273-1177); 7; 12, 1
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  • 23
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    The magnetic field of Uranus (1987)
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    Publication Date: 2011-08-19
    Description: Aspherical harmonic model of the planetary magnetic field of Uranus is obtained from the Voyager 2 encounter observations using generalized inverse techniques which allow partial solutions to complex (underdetermined) problems. The Goddard Space Flight Center 'Q3' model is characterized by a large dipole tilt (58.6 deg) relative to the rotation axis, a dipole moment of 0.228 G R(Uranus radii cubed) and an unusually large quadrupole moment. Characteristics of this complex model magnetic field are illustrated using contour maps of the field on the planet's surface and discussed in the context of possible dynamo generation in the relatively poorly conducting 'ice' mantle.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 15329-15
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  • 24
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    Survey of electrons in the Uranian magnetosphere - Voyager 2 observations (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Results of an analysis of the Voyager 2 plasma-science-experiment electron measurements made during the Uranus encounter are presented. The energy coverage is in the range of 10 to 5950 eV. The large day-night asymmetry together with the spin axis alignment with the solar direction and the large tilt of the planetary magnetic dipole suggest that solar-wind-driven time-dependent magnetospheric convection will be an important transport mechanism within the Uranian magnetosphere. The steady state convection time of the plasma is estimated to be between 1 and 3 days.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 15263-15
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  • 25
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    Surface waves on Uranus' magnetopause (1987)
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    Publication Date: 2011-08-19
    Description: Uranus' magnetosphere has a well-developed, thick magnetopause that was fully traversed twice by Voyager 2, once inbound to the planet and once outbound. This boundary appears to resemble earth's magnetopause in approximate shape and even to the extent of supporting surface waves which were observed on the inbound pass at a distance of 18.3 Uranus radii. There were apparently eight partial transitions from the magnetosheath into the current sheet of the magnetopause at this time, followed by a final complete transition to the magnetosphere. Six of the estimated normal vectors to the local boundary show clear evidence of oscillations in the slope with typical angular excursions, from one partial transition to the next, of about 90 deg. The vectors oscillated approximately in a plane that was severely tilted by about 49 deg with respect to Uranus' orbital plane.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 15347-15
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  • 26
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    Ordinary mode radio emission from Uranus (1987)
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    Publication Date: 2011-08-19
    Description: On Jan. 24, 1986, during the inbound trajectory to Uranus, the planetary radio astronomy instrument on Voyager 2 detected left-hand-polarized emission for several hours at frequencies near 200 kHz. Unlike the dominant source observed on the nightside of the planet, only a single episode of this inbound emission was seen, and the emission was extremely weak. Generating less than 500 kW, it is probably the weakest freely propagating planetary radio emission thus far observed by Voyager. This weak emission is associated with a source region in the vicinity of the north (dayside) magnetic pole of Uranus, where magnetic-field lines point approximately in the direction of the spacecraft when the emission is observed. Therefore the wave normal angle relative to B is probably less than 90 deg in the generation region. It is concluded that direct wave generation in the magnetoionic ordinary mode is most likely. The source location for this emission is consistent with a region magnetically conjugate to the dominant nightside source, which is located in the vicinity of the south magnetic pole. The ordinary mode emission is discussed in the context of the electron-cyclotron maser mechanism.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 15211-15
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  • 27
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    Uranus satellites - Densities and composition (1987)
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    Publication Date: 2011-08-19
    Description: Homogeneous and core-differentiated silicate/ice models of the Uranian satellites Miranda, Ariel, Umbriel, Titania, and Oberon are examined in the light of imaging observations and mass and density determinations obtained during the Voyager 2 encounter with Uranus in January 1986. The data and model predictions are compared in extensive tables and graphs and discussed in detail. The mass fractions of silicates in Oberon and Titania are found to be between 0.42 and 0.65, about the same as the average for the satellites of Jupiter and Saturn but significantly higher than that for the smaller Saturnian satellites or that predicted by current solar-nebula models. It is suggested that the satellites formed by accretion of material from their primary planets' outer envelopes. The observed rock/ice fractions are attributed to solar-nebula CO and solid-organics abundances and to preferential dissolution of H2O in outer-envelope planetesimals.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 14884-14
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  • 28
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    Isotopic analysis of basaltic fragments from lunar breccia 14321 - Chronology and petrogenesis of pre-Imbrium mare volcanism (1987)
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    Publication Date: 2011-08-19
    Description: Internal (mineral) Rb-Sr isochrons were determined for six Apollo 14 mare basalts of lunar breccia 14321. The ages of these fragments, which represent the time of crystallization of the respective mafic lavas, range from about 4.05 to 4.24, and, possibly, to 4.33 Ga and are among the oldest dates reported for mare basalts. For three of the fragments, internal Sm-Nd isochron data were collected and initial Nd isotopic composition was determined. The results are discussed with reference to the original source of these different basaltic fragments.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta (ISSN 0016-7037); 51; 3241-325
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  • 29
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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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    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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    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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    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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    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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    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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    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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    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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    Radiometry of Deimos (1987)
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    Publication Date: 2011-08-19
    Description: Ground-based infrared photometry of Deimos at 4.8, 10, and 20 microns is reported. The observed fluxes are significantly brighter than predicted by the 'standard' thermal model. Recent recalibrations that modify the model beam pattern of the infrared emission are marginally consistent with the observations at 10 and 20, but not at 4.8 microns.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astronomical Journal (ISSN 0004-6256); 94; 1361-136
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    Boreal forests and atmosphere - Biosphere exchange of carbon dioxide (1987)
    In:  Other Sources
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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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  • 40
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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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    Refractory interplanetary dust particles (1987)
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    Publication Date: 2011-08-19
    Description: Criteria are described by which refractory interplanetary dust particles (IDPs) can be differentiated from the products of spacecraft debris. These criteria have been used to discover and characterize IDPs that are composed predominantly of refractory phases. Two of these particles contain hibonite, perovskite, spinel, refractory glass, and a melilite; only hibonite was identified within a third. The grain size for all particles ranges from 0.05 to 1 micrometer, so that they are much finer grained than the refractory calcium- and aluminum-rich inclusions in meteorites. The glass-containing refractory IDPs may be primitive nebular condensates that never completely crystallized and thus have been preserved extant.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 237; 1466-146
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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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    Detection of a hot plasma component within the core regions of Jupiter's distant magnetotail (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Voyager-2 PLS low-energy plasma data and the magnetometer data are combined with the the LECP ion data (E greater than 28 keV) for the distant magnetotail observations (R = 5000-9000 Jupiter radii). A definite enhancement of LECP fluxes within the core regions (where the PLS densities and magnetic-field pressure are lower than in the surrounding regions) is shown, indicating that this hot tenuous plasma is present within the core regions. In general there is a strong anticorrelation between PLS density and LECP fluxes, while a less pronounced anticorrelation between magnetic-field pressure and LECP fluxes is observed. Estimates of LECP pressures suggest that this hot plasma can provide the previously described missing pressure in the core if heavy ions dominate the ion composition. The angular dependence of the LECP data indicates a flow of this hot plasma in the anti-Jupiter direction. This outflowing plasma could be the remnant of the magnetospheric wind observed near Jupiter by LECP. On the basis of this preliminary study, the core regions are found to have similarities to a plasma sheet.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 9943-994
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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)
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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)
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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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    Infrared spectroscopic measurements of halogenated source gases in the stratosphere with the ATMOS instrument (1987)
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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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    Shock effects and argon loss in samples of the Leedey L6 chondrite experimentally shocked to 29-70 GPa pressures (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The recovery of polished 600-micron-thick 7-mm-diameter disk samples and powder samples of the Leedey L6 chondrite from 29-70-GPa experimental shocks is investigated experimentally under vacuum conditions, with a focus on the possible direct shock loss of radiogenic Ar. The results of petrographic examination of the shocked samples and Ar isotope measurements are presented in tables, graphs, and micrographs and characterized in detail. The principal damage mechanisms are identified as mechanical disaggregation and increasing cataclasis, with little melting. The degassing of radiogenic Ar is found to be relatively modest and to increase with shock pressure and sample porosity; it is attributed to a combination of mechanical grain disruption and feldspar melting. It is inferred that Ar loss in naturally shocked materials (especially those showing few signs of melting) probably occurs during extended exposure to high temperatures during impact formation.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta (ISSN 0016-7037); 51; 2035-204
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    Optical efficiencies of lightning in planetary atmospheres (1987)
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    Publication Date: 2011-08-19
    Description: The first simulations of lightning in planetary atmospheres by laser-induced plasmas are reported. These simulations show that the fraction of the energy in lightning discharge channels that is radiated in the visible spectrum is similar for earth, Venus, and Titan, but quite different for Jupiter. One implication of these results is that the amount of trace gases produced by lightning in the Jovian atmosphere must be larger than previously estimated.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 328; 509
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    Observed beaming of terrestrial myriametric radiation (1987)
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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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    Landform identification in lunar radar images (1987)
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    Publication Date: 2011-08-19
    Description: Lunar radar images have been investigated in order to understand how various radar parameters affect landform identification. The high-resolution (1-2 km cell size) 3.8-cm images of Zisk et al. (1974) were used along with the low and high resolution 70-cm mosaics of Thompson (1974 and 1987). The results indicate that radar cell size is the single most important radar parameter and that lunar features are likely to be correctly identified if they are longer than an 'identification resolution' of five times the radar cell size. The moon is considered here as an analog of Venus, since the two planets have similar mean scattering behavior.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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    Ice measurements by Geosat radar altimetry (1987)
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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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    Snow load effect on earth's rotation and gravitational field, 1979-1985 (1987)
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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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    Investigation of Martian H2O and CO2 via orbital gamma ray spectroscopy (1987)
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    Publication Date: 2011-08-19
    Description: The capability of an orbital gamma ray spectrometer to address presently unanswered questions concerning H2O and CO2 on Mars is investigated. The gamma ray signal produced by the Martian atmosphere and by several simple models of Martian surface materials is calculated. Results are reported for: (1) the production of neutrons in the atmosphere and in the subsurface material by cosmic ray interactions, (2) the scattering of neutrons and the resultant neutron energy spectrum and spatial distributions, (3) the reproduction of gamma rays by neutron prompt capture and nonelastic scatter reactions, (4) the production of gamma rays by natural radionuclides, (5) the attenuation of the gamma ray signal by passage through surface materials and the Martian atmosphere, (6) the production of the gamma ray continuum background, and (7) the uncertainty in gamma ray line strengths that results from the combined signal and background observed by the detector.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 9153-916
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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)
    In:  Other Sources
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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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    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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  • 60
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    Aerosol optical depth and planetary Albedo in the visible from the Solar Mesosphere Explorer (1987)
    In:  Other Sources
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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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    Comparison of the compositions of Venusian surface rocks with those of the terrestrial ocean floor (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A statistical comparison of data on the composition of the Venusian surface obtained with Venera and Vega lander X-ray fluorescence spectrometers and data on the composition of the terrestrial ocean floor indicates that the Venera 14 data correspond to certain thoeiitic basalts of the Kane fracture zone in the Middle-Atlantic ridge (22-25 deg N). It is suggested that deep magma storage regions exist on Venus and that the separation of tholeiitic and alkali magmas from a single primitive parent magma is an important process on Venus.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astronomicheskii Vestnik (ISSN 0320-930X); 21; 122-135
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  • 62
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    Planning the Voyager spacecraft's mission to Uranus (1987)
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    Publication Date: 2011-08-19
    Description: The application of the systems engineering process to the planning of the Voyager spacecraft mission is described. The Mission Planning Office prepared guidelines that controlled the use of the project and multimission resources and spacecraft consumables in order to obtain valuable scientific data at an acceptable risk level. Examples of mission planning which are concerned with the design of the Deep Space Network antenna, the uplink window for transmitting computer command subsystem loads, and the contingency and risk assessment functions are presented.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Irish Astronomical Journal (ISSN 0021-1052); 18; 40
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  • 63
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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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  • 64
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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)
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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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    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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  • 66
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    Behavior of ionized plasma in the high latitude topside ionosphere - The polar wind (1987)
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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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  • 67
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    Crustal geologic studies with Magsat and surface magnetic data (1987)
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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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  • 68
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    The time-varying geomagnetic field (1987)
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    Publication Date: 2011-08-19
    Description: Information (obtained from Magsat and other sources) published by the U.S. authors between 1983 and 1986 on the large-scale geomagnetic field of deep internal origin and its secular variation (SV) is reviewed. Results on the main field modeling, including reference fields, and on the separaton of core and crustal fields are discussed together with the advances made in geomagnetic field theory and applications of novel methods. Consideration is also given to global SV, short-term global SV, and regional CV analyses; nonsecular impulses, featuring the sudden geomagnetic jerk of 1969; and the frozen-flux core approximation, including downward continuation to the core-mantle boundary constraints, westward drift, and estimates of the fluid velocity at the top of the core.
    Keywords: GEOPHYSICS
    Type: Reviews of Geophysics (ISSN 8755-1209); 25; 929-938
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    The use of atmospheric measurements to constrain model predictions of ozone change from chlorine perturbations (1987)
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    Publication Date: 2011-08-19
    Description: Atmospheric photochemistry models have been used to predict the sensitivity of the ozone layer to various perturbations. These same models also predict concentrations of chemical species in the present day atmosphere which can be compared to observations. Model results for both present day values and sensitivity to perturbation depend upon input data for reaction rates, photodissociation rates, and boundary conditions. A method of combining the results of a Monte Carlo uncertainty analysis with the existing set of present atmospheric species measurements is developed. The method is used to examine the range of values for the sensitivity of ozone to chlorine perturbations that is possible within the currently accepted ranges for input data. It is found that model runs which predict ozone column losses much greater than 10 percent as a result of present fluorocarbon fluxes produce concentrations and column amounts in the present atmosphere which are inconsistent with the measurements for ClO, HCl, NO, NO2, and HNO3.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 6662-667
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  • 70
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    Measurements of mesospheric water vapor in 1984 and 1985 - Results and implications for middle atmospheric transport (1987)
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    Publication Date: 2011-08-19
    Description: The detailed results of ground-based mesospheric water vapor measurements obtained by microwave spectroscopy at the Jet Propulsion Laboratory (JPL) from December 1984 to April 1985 (JPL 1984/85), and an overview of results obtained the previous year from April to June 1984 are presented. The JPL 1984/85 spectral data appeared to contain an instrumental baseline curvature which was bracketed and removed. In general, the JPL 1984/85 results are in good agreement with those of previous measurements. They indicate water vapor mixing ratios between 6 and 8 ppmv at 60 or 65 km and falling off steeply with height above this point to values of less than 2 ppmv at 80 km. In addition, there is a large amount of day-to-day variability indicated in the data. A major result of the study is that it is found that both the observed vertical gradient of water vapor mixing ratio and its seasonal variation are consistent with the hypothesis that vertical transport time scales are smaller, perhaps by an order of magnitude, than values currently used in both one- and two-dimensional photochemical/dynamical models.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 6679-669
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    Distribution of total ozone and stratospheric ozone in the tropics - Implications for the distribution of tropospheric ozone (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Climatologies of total columnar ozone and integrated stratospheric ozone amounts at low latitudes (15 deg N to 15 deg S), derived from satellite observations, are presented. A significant longitudinal variability in total ozone is present, with highest values generally located between 60 deg W and 60 deg E. The integrated stratospheric component of total ozone, on the other hand, does not exhibit a longitudinal preference for high values. Therefore it is hypothesized that the climatological longitudinal distribution of total ozone reflects the variability of the abundance of tropospheric ozone at low latitudes. Furthermore, it is speculated that in situ photochemical production of ozone resulting from biomass burning may be responsible for the observed enhancement of total ozone at these longitudes.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 6627-663
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  • 72
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    Geomagnetic response to magnetic clouds (1987)
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    Publication Date: 2011-08-19
    Description: Results of superimposed epoch analyses of hourly values of the equatorial Dst geomagnetic index and the B(x) component of the interplanetary magnetic field are given for 19 magnetic clouds. Results show statistical associations between magnetic clouds and geomagnetic storms, and between clouds without preceding shocks and gradual commencements. It was found that 75 percent of the clouds had a maximum Dst of less than -30 gammas, and that 95 percent of the clouds had a maximum Dst of less than about -16 gammas. In the main phase and recovery phase of geomagnetic storms, the Dst index simultaneously decreases to a large negative value at the onset of a large sustained southward magnetic field, and recovery starts when the magnetic field becomes northward.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science (ISSN 0032-0633); 35; 329-335
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    Statistical properties of magnetic field fluctuations in the distant plasmasheet (1987)
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    Publication Date: 2011-08-19
    Description: Short (less than 1 min) and long time (greater than 5 min) variations of the plasmasheet magnetic field have been examined during all intervals when ISEE-3 was at distances x less than -200 earth radii. It is determined that short period magnetic turbulence increases by a factor of about 3 with increasing geomagnetic activity, as indicated by AE. In contrast, long period field variations with North-then-South signatures at plasmasheet entry occur about 2.5 times more frequently than South-then-North signatures. This result, combined with other previous ISEE-3 results, is in agreement with the interpretation that the North-South plasmasheet features are plasmoids propagating tailward. However, a statistical examination of the geomagnetic activity relationship indicates that there does not appear to be any substorm dependence on these North-South events.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science (ISSN 0032-0633); 35; 289-293
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    Distant (200-238 earth radii) magnetotail lobe characteristics during quiet solar wind conditions (1987)
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    Publication Date: 2011-08-19
    Description: Simultaneous ISEE-3 magnetic field and IMP-8 magnetic field and plasma data have been used to investigate the distant tail lobe average properties under quiet solar wind conditions. Under solar wind pressures of not greater than 5 x 10 to the -10th dynes/sq cm, an average tail lobe strength of 7.1 + or - 1.2 nT, and an average plasma beta of 0.3, are found. Results suggest that under quiet solar wind conditions the distant tail lobes are relatively free from plasma and are usually dominated by the magnetic field pressure.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science (ISSN 0032-0633); 35; 285-288
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    The production of O(1S) from dissociative recombination of O2(+) (1987)
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    Publication Date: 2011-08-19
    Description: The first theoretical calculations of the rate coefficient alpha for dissociative recombination of O2(+) leading to O(1S) are reported for a wide range of temperatures. The findings are discussed in terms of the potential energy curves for the ground state of O2(+) and for the dissociative 1Sigma(u) state calculated here. Values of alpha for the equilibrium case in which the electron and vibrational temperatures are identical are shown.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 327; 408
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    Plume formation in the D-double prime-layer and the roughness of the core-mantle boundary (1987)
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    Publication Date: 2011-08-19
    Description: A series of very-high-resolution finite element calculations of plume formation in the D-double prime-layer has been performed for several plausible rheologies and boundary conditions in order to study both the early and later stages of boundary layer development. The results show that plumes are initiated by coalescence of small-scale convective instabilities within the low-viscosity region immediately above the core-mantle boundary (CMB). These instabilities support topographic roughness on the CMB having horizontal scales of 20-50 km and provide a source for scattered P-waves seen as precursors to the phases PKIKP and PKKP. The calculated structure of fully developed plumes emerging from the D-double prime-layer consists of 5-50 cm/yr flow confined to 50-100 km thick vertical conduits. With strongly temperature-dependent viscosity, plumes exhibit time-dependent behavior, including upward propagating solitary conduit waves, which may contribute to episodicity in hotspot volcanism.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 327; 409-413
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    Trace gas measurements from tethered balloon platforms (1987)
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    Publication Date: 2011-08-19
    Description: Instrumentation and chemical sampling and analysis procedures are described for making measurements of atmospheric carbon disulfide in the concentration range 1-1000 pptv from tethered balloon platforms. Results of a study on the CS2 composition of air downward of a saltwater marsh are reported. A method for obtaining the necessary data for solving the budget equations for surface fluxes, chemical formation rates and chemical destruction rates using data acquired from tethered balloon platforms is presented.
    Keywords: GEOPHYSICS
    Type: Journal of Atmospheric and Oceanic Technology (ISSN 0739-0572); 4; 227-232
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    General comparison of ozone vertical profiles obtained by various techniques during the 1983 MAP/GLOBUS campaign (1987)
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    Publication Date: 2011-08-19
    Description: As part of the 1983 MAP/GLOBUS campaign, atmospheric ozone profile measurements were made using a large variety of different techniques both from balloon platforms and the ground. It is shown that, for most techniques, the measured height distributions agree to within + or - 5 percent with the exception of the remote visible absorption method. This + or - 5 percent uncertainty is of the order of the individual intersystem accuracy. It is suggested that since the differences with the visible absorption method are in magnitude rather than in form, the absorption cross-section data could be the possible cause for the discrepancy.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science (ISSN 0032-0633); 35; 603-607
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    Ozone measurements of the NASA-JSC U.V. photometer during the MAP/GLOBUS campaign of 1983 (1987)
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    Publication Date: 2011-08-19
    Description: Results of the NASA-JSC UV photometer from flights on large balloons during the MAP/GLOBUS campaing of September 1983 are reported. Profiles obtained on September 14 and 24 agree within uncertainties above a height of 36 mb (about 22.5 km) indicating a degree of stability in the upper stratosphere. Measurements were made during ascent and descent of the first flight, and ascent of the second flight. Because the vertical descent rate of the first flight was five times lower than the ascent rate, more structure was obtained. Float altitudes of 32 km (8.1 mb) for the first flight and 39 km (3.1 mb) for the second flight were attained. Results from the photometer are compared with Nimbus 7 SBUV observations made at the same time. The profiles agree within 10 percent above the partial pressure peak. Above the ozone mixing ratio peak, the UV photometry values are about 1 ppmV lower for the second flight. The SBUV profile peak is 1-2 km higher in altitude than that of the UV photometer. Peak values agree within about 4 percent.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science (ISSN 0032-0633); 35; 587-593
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    Comparison of in situ stratospheric ozone measurements obtained during the MAP/GLOBUS 1983 campaign (1987)
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    Publication Date: 2011-08-19
    Description: Data from five types of in situ ozone sensors flown aboard ballons during the MAP/GLOBUS 1983 campaign were found to agree to within 5 percent uncertainty throughout the middle atmosphere. A description of the individual techniques and the error budget is given in addition to explanations for the discrepancies found at higher and lower altitudes. In comparison to UV photometry values, results from two electrochemical techniques were found to be greater in the lower atmosphere and to be lower in the upper atmosphere. In general, olefin chemiluminescence results were within 8 percent of the UV photometry results. Ozone column contents measured by the indigo colorization technique for two altitude regions of about 6 km height were greater than measurements from other techniques by 52 and 17 percent, respectively.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science (ISSN 0032-0633); 35; 563-565
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    Analysis and comparison of ozone maps obtained by TOMS and TOVS during the MAP/GLOBUS 1983 campaign (1987)
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    Publication Date: 2011-08-19
    Description: The Nimbus 7 TOMS (UV) and NOAA 7 and NOAA 8 TOVS (IR) data have been specially processed for the MAP/GLOBUS campaign (September 1983, over Europe). Comparison of the ozone results shows a general agreement but also some discrepancies due to clouds, emissivity of the surface, and latitude effects. The variability of the ozone field, closely linked to geopotential height field, may have induced a great change in total ozone along the balloon flights, but fortunately trajectories tend to lie parallel to the total ozone contours, so that the total ozone during each flight is nearly constant.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science (ISSN 0032-0633); 35; 539-545
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    Chemistry of the solar system: An elementary introductionto cosmochemistry (1987)
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    Publication Date: 2011-08-19
    Description: An introduction is presented to the chemistry of the solar system. The qualitative and quantitative elemental analysis of the solar system is reviewed, and the elemental synthesis processes that led to the formation of the solar system are discussed. The chemical processes of the primordial mixture from which the solar system formed are examined, and the resulting chemical composition of meteorites, asteroids, comets, and planets is described.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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    Tidal influences on vertical diffusion and diurnal variability of ozone in the mesosphere (1987)
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    Publication Date: 2011-08-19
    Description: Possible dynamical influences on the diurnal behavior of ozone are investigated. A time dependent one-dimensional photochemical model is developed for this purpose; all model calculations are made at 70 deg N during summer. It is shown that the vertical diffusion can vary as much as 1 order of magnitude within a day as a result of large changes in the zonal wind induced by atmospheric thermal tides. It is found that by introducing a dissipation time scale for turbulence produced by breaking gravity waves, the agreement with Poker Flat echo data is improved. Comparisons of results from photochemical model calculations, where the vertical diffusion is a function of height only, with those in which the vertical diffusion coefficient is changing in time show large differences in the diurnal behavior of ozone between 70 and 90 km. By including the dynamical effect, much better agreement with the Solar Mesosphere Explorers data is obtained. The results are, however, sensitive to the background zonally averaged wind. The influence of including time-varying vertical diffusion coefficient on the OH densities is also large, especially between 80 and 90 km. This suggests that dynamical effects are important in determining the diurnal behavior of the airglow emission from the Meinel bands.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 5609-562
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    Equatorial ozone profiles from the ground to 52 km during the Southern Hemisphere autumn (1987)
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    Publication Date: 2011-08-19
    Description: The results of an ozone measurement campaign conducted at Natal, Brazil from March 25 to April 15, 1985 are reported. Complete profiles of ozone, pressure, and temperature were obtained from the ground to 52 km, and all of the profiles correspond with site overpasses by ozone instruments on NASA and NOAA satellites. The profiles from this measurement series show reasonable agreement with established satellite climatologies. Stratospheric ozone variability was 2 percent or less during the 3 weeks of the measurement campaign, with stratospheric temperature and pressure variabilities half that amount. Low variability at a single location for this period implies comparable uniformity for ozone profiles over a large area around the measurement site. The auxiliary pressure and temperature profiles presented here allow the use of this data set as a transfer standard between satellite instruments with different fundamental ozone measurements. Finally, the low ozone variability in the stratosphere at Natal during this measurement series should provide an opportunity for high-quality intercomparisons of measured and modeled ozone concentrations in the equatorial stratosphere and lower mesosphere as well as a consistency check among satellite ozone measurements.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 5573-558
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    Numerical simulations of collisions between rotating particles (1987)
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    Publication Date: 2011-08-19
    Description: Numerical simulations of Keplerian systems consisting of 200 mutually colliding rotating particles show that friction and surface irregularity reduce the equilibrium velocity dispersion and transfer some of the energy of random velocities to rotational velocities. The results confirm the theoretical predictions of Salo (1987). Simulations are performed for identical and different particle sizes, and for a power-law distribution of sizes. Taking rotation into account is not found to alter the previously observed Rayleigh distribution of eccentricities and inclinations, while the components of the rotational velocities are found to follow a Gaussian distribution. Application to the rarefied regions of Saturn's rings suggests that friction is able to reduce the equilibrium geometric thickness by about one-half.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 70; 37-51
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  • 86
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    Physical and chemical modification of the surface of Venus by windblown particles (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The results of simulations of the Venusian surface environment involving windblown grains are presented which show that significant chemical and physical changes may occur even in the slow-moving winds recorded on Venus. The edges of grains beome worn and shed comminuted debris, which collects on weathered surfaces and grains alike. The resulting transfer of material from loose grains to bedrock surfaces (and vice versa) could yield misleading results on rock composition; moreover, the generation of comminuted debris would enhance chemical reactions that could affect the composition of the atmosphere. The results are thus relevant in assessing rates of surface degradation, the evolution of small-scale surface features as seen in images returned from the Soviet Venera missions, and in the interpretation of compositional data for surface materials.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 327; 313-315
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  • 87
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    IRAS constraints on the sizes of Pluto and Charon (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Thermal emission models indicate that Charon contributes a significant amount of the infrared radiation detected by IRAS during the observation of mutual eclipse events. The IRAS observations also show that the most probable diameters for Pluto and Charon are 2200 and 1300 (+ or - 150) km. These results are consistent with there being some atmosphere on Pluto.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 327; 127-129
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  • 88
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    Numerical simulations of magnetospheric plasmas - Review and quadrennial report to the IUGG (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: This article provides a broad survey of U.S. progress during the quadrennium 1983-1986 in the category 'numerical simulations of magnetospheric plasmas'. There has been a substantial increase of activity in this area during this period. Simulations have been instrumental in providing valuable insights into large scale dynamic phenomena, nonlinear effects, and complex kinetic phenomena in a wide variety of subject areas, including shocks and double layers, ionosphere-magnetosphere coupling phenomena, and important microphysical processes such as broadband electrostatic noise. The methodology of computer simulation has also been advanced during this quadrennium. Vlasov algorithms have been improved; hybrid codes in 2 and 3D have been developed and applied to magnetospheric problems; and complex problems have been subjected with increasing frequency to a multipronged attack in which several types of simulation models, each designed to accurately model phenomena within a particular range of temporal or spatial scales, are employed synergistically.
    Keywords: GEOPHYSICS
    Type: Reviews of Geophysics (ISSN 8755-1209); 25; 599-613
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  • 89
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    Dynamics of the middle atmosphere (1987)
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    Publication Date: 2011-08-19
    Description: Research performed in the U.S. from October 1982 to May 1986 on the middle-atmosphere dynamics is reviewed. The topics discussed include extratropical large- and medium-scale waves and instabilities, gravity waves, tropical motions, and the general circulation. In addition, consideration is given to the studies of atmosphere constituent transport. A number of studies in the latter area have shed light on the specific seasonal behavior of dynamically controlled important constituents in the stratosphere, such as ozone, water vapor, and aerosols.
    Keywords: GEOPHYSICS
    Type: Reviews of Geophysics (ISSN 8755-1209); 25; 501-507
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  • 90
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    Tail modeling in a stretched magnetosphere. I - Methods and transformations (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A new method is developed for representing the magnetospheric field B as a distorted dipole field. Because Delta-B = 0 must be maintained, such a distortion may be viewed as a transformation of the vector potential A. The simplest form is a one-dimensional 'stretch transformation' along the x axis, concisely represented by the 'stretch function' f(x), which is also a convenient tool for representing features of the substorm cycle. One-dimensional stretch transformations are extended to spherical, cylindrical, and parabolic coordinates and then to arbitrary coordinates. It is shown that distortion transformations can be viewed as mappings of field lines from one pattern to another; the final result only requires knowledge of the field and not of the potentials. General transformations in Cartesian and arbitrary coordinates are derived, and applications to field modeling, field line motion, MHD modeling, and incompressible fluid dynamics are considered.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 4437-444
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  • 91
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    Comment on 'Heavy ozone in the stratosphere' (1987)
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    Publication Date: 2011-08-19
    Description: It is suggested that the factor-of-two difference in ozone formation rate constants derived by Bates (1986) can also be explained by the omission of standard correction factors from the rate expression. Proper accounting for the fact that isotope exchange and recombination reactions share a common energized collision complex (which can decay by dissociation to products isotopically distinct from the original reactants) eliminates the anomalous dependence of the rate constant on the isotopic composition of the reactants and products through their symmetry numbers. In a reply, Bates argues that symmetry effects in association do not lead to enhancement of the total heavy ozone abundance.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 14; 91-93; R
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  • 92
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    Structure of a slow mode shock observed in the plasma sheet boundary layer (1987)
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    Publication Date: 2011-08-19
    Description: A detailed study of the plasma parameters and magnetic field measured using instrumentation aboard ISEE 2 during the recovery phase of a substorm on Apr. 24, 1979, is presented. The purpose of this study was to determine the nature and structure of the lobe-plasma sheet boundary layer. The analysis shows that the lobeward edge of the boundary is consistent with a freestanding slow mode shock. This shock is followed by a slow compression wave containing a trailing ion cyclotron wave which also stands in the flow. Measurement of the cross-tail current in the shock and the current system within the wave gives a shock thickness and wavelength comparable to but larger than both the upstream ion inertial length and the downstream proton gyroradius. Equality of the shock thickness with the standing ion cyclotron wavelength suggests that the steepness of the front is limited by dispersion rather than current-driven anomalous resistivity.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 83-94
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  • 93
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    Temperature and aerosol structure of the nightside Uranian stratosphere from Voyager 2 photopolarimeter stellar occultation measurements (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Voyager 2 UV-photopolarimeter occultation observations toward Gamma Peg, obtained on the nightside of Uranus at planetocentric latitude 68.9 deg N on January 24, 1986, are used to probe the structure of the Uranian atmosphere. The data are presented graphically and compared with the predictions of model atmospheres. The temperature profile for an aerosol-free atmosphere ranges from 85 + or - 2.3 K at 2.7 mbar to 96 + or - 13 K at 370 microbar, and the 1-mbar radius is found to be 25,219 + or - 6.3 km. The extinction coefficient for an aerosol haze layer at 1 mbar or higher is shown to be less than or equal to about 0.0001/km, but it is suggested that a well-mixed haze layer consisting of meteor or ring dust and/or photochemical condensates may well be present below 3 mbar.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 15030-15
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  • 94
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    The helium abundance of Uranus from Voyager measurements (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Voyager radio-occultation and IR spectroscopy measurements are combined to infer an He mole fraction in the upper troposphere of Uranus of 0.152 + or - 0.033; the corresponding mass fraction is Y = 0.262 + or - 0.048. This value is in agreement with recent estimates of the solar He abundance, suggesting that He differentiation has not occurred on Uranus. Comparisons with values previously obtained for Jupiter and Saturn imply that migration of He toward the core began long ago on Saturn and may also have recently begun on Jupiter. The protosolar He abundance inferred from the Uranus measurements and from recent solar evolutionary models is used along with an assumed primordial He mass fraction of 0.23-0.24 to estimate a 3-4-percent enrichment of He in the interstellar medium between the big bang and the origin of the solar system. The result is in agreement with galactic chemical evolution models which include a substantial decrease in D during the evolutionary process.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 15003-15
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  • 95
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    The atmosphere of Uranus - Results of radio occultation measurements with Voyager 2 (1987)
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    Publication Date: 2011-08-19
    Description: The Uranian atmosphere is investigated on the basis of S-band and X-band occultation observations (including measurements of Doppler frequency perturbations) obtained during the Voyager 2 encounter with Uranus in January 1986. The data are presented in extensive tables and graphs and characterized in detail. The atmosphere is assumed to have an H2/He abundance ratio of about 85/15, but also to contain small amounts of CH4 at above-cloud relative humidity 30 percent, cloud-base relative humidity 78 percent, and below-cloud mixing ratio 2.3 percent by number density. Other parameters estimated include magnetic-field rotation period 17.24 h, 1-bar equatorial radius 25,559 + or - 4 km, polar radius 24,973 + or - 20 km, equatorial acceleration of gravity 8.69 + or - 0.01 m/sec sq, and atmospheric temperature 76 + or - 2 K (assuming 85 + or - 3 percent H2).
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 14987-15
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  • 96
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    Voyager infrared observations of Uranus' atmosphere - Thermal structure and dynamics (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The temperature structure of the Uranus atmosphere is investigated on the basis of 325/cm and 225/cm Voyager 2 IRIS observations of a layer between 60 and 200 mbar (including the tropopause). The data are presented in graphs and analyzed in detail. The latitudinal variations of the temperature near the tropopause and the inferred thermal winds are shown to be in good agreement with the findings reported for lower altitudes by Hanel et al. (1986), although greater in amplitude. A linear zonally symmetric circulation model with no solar and condensation heating, a frictional damping time 1-2 times the radiative damping time, a subrotating atmosphere at low latitudes, and zonal winds decaying with altitude is proposed to account for the observed structures.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 15011-15
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  • 97
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    Cratering history of the Uranian satellites - Umbriel, Titania, and Oberon (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Crater size-frequency data for Umbriel, Titania, and Oberon are presented, and the implications of those data are discussed in terms of the geologic histories of these bodies and the populations of objects that have cratered them. The surfaces of Oberon and Umbriel are old and are inferred to date to a period early in their histories when the cratering rate was significantly higher than at present. No significant endogenic resurfacing appears to have occurred on either body after that inferred period of intense cratering. Titania exhibits the youngest surface of these three and appears to have undergone almost complete endogenic resurfacing. Among the Uranian satellites the surfaces of Oberon and Umbriel are interpreted to be the oldest, that of Titania intermediate, and those of Ariel and parts of Miranda the youngest. The size-frequency distributions for these satellites have an average slope of about -3, indicative of a steep crater production function. The cumulative size-frequency data for these Uranian satellites may be interpreted to indicate that parts of their surfaces are saturated with craters at small diameters.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 14918-14
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  • 98
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    Zhamanshin and Aouelloul - Craters produced by impact of tektite-like glasses? (1987)
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    Publication Date: 2011-08-19
    Description: It is shown that the enhanced abundance of siderophile elements and chromium in tektite-like glasses from the two impact craters of Zhamanshin and Aouelloul cannot be explained as a result of contamination of the country rock by meteorites nor, probably, comets. The pattern is, however, like that found in certain Australasian tektites, and in Ivory Coast tektites. It is concluded, in agreement with earlier suggestions by Campbell-Smith and Hey, that these craters were formed by the impact of large masses of tektite-like glass, of which the glasses which were studied are fragments. It follows that it is necessary, in considering an impact crater, to bear in mind that the projectile may have been a glass.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Meteoritics (ISSN 0026-1114); 22; 219-228
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  • 99
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    Tectonic motion in the western United States inferred from very long baseline interferometry measurements, 1980-1986 (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Over six years of mobile very long baseline interferometry (VLBI) baseline measurements between 12 sites in the western U.S. were used to infer their velocities relative to the North American plate. These velocities were found to be generally consistent with those determined from geologic data and contemporaneous satellite laser ranging measurements in the same region. The discrepancy between the largest velocities determined from the VLBI measurements of 40-48 mm/yr and the relative plate velocity of 50-56 mm/yr predicted from plate motion models is found to be consistent with a broadened distribution of interseismic strain from cyclic activity on the San Andreas and subsidiary faults. The VLBI data are best explained by a cumulative rate of strike-slip motion near the plate boundary of approximately 48 mm/yr, although exclusion of competing values of 56 and 41 mm/yr is based upon very few data. The rates of offshore fault slip inferred from this study range from about 15 mm/yr in central California to negligible amounts in the San Francisco region. Finite element calculations of multiple fault strain distributions show good agreement with systematic variations in the distribution of shear strain along the San Andreas system, as revealed by previous geodetic measurements.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 14151-14
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  • 100
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    Background stratospheric aerosol reference model (1987)
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    Publication Date: 2011-08-19
    Description: Nearly global SAGE I satellite observations in the nonvolcanic period from March 1979 to February 1980 are used to produce a reference background stratospheric aerosol optical model. Zonally average profiles of the 1.0-micron aerosol extinction for the tropics, midlatitudes, and high latitudes for both hemispheres are given in graphical and tabulated form for the different seasons. A third order polynomial fit to the vertical profile data set is used to derive analytic expressions for the seasonal global means and the yearly global mean. The results have application to the simulation of atmospheric radiative transfer and radiance calculations in atmospheric remote sensing.
    Keywords: GEOPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 7; 9, 19
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