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  • GEOPHYSICS  (823)
  • LUNAR AND PLANETARY EXPLORATION  (585)
  • 1985-1989  (1,408)
  • 1950-1954
  • 1925-1929
  • 1988  (1,408)
Collection
Keywords
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  • 1985-1989  (1,408)
  • 1950-1954
  • 1925-1929
Year
  • 1
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    The Lunar Orbital Prospector (1988)
    In:  CASI
    Details
    Publication Date: 2005-07-19
    Description: The Moon is a body rich in natural resources and full of intriguing scientific questions, and it will most certainly play a central role in the growth of near-Earth and deep space ventures of the twenty-first century. The LOP mission is an example of one way to catalog the Moon's natural resources and to answer lunar science questions in parallel. In a realistic planetary exploration program, this mission must compete with other interesting planetary missions and therefore the LOP must be as low cost and adaptable as possible. This flexibility is reflected in the LOP's heavy design emphasis on modularity. The LOP mission can easily be expanded to include new technologies, and additional orbiters could be launched into lunar orbit to provide a constellation of remote-sensing platforms. This design thus projects a broad range of possibilities for continued lunar exploration in the next century.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: USRA, NASA(USRA University Advanced Design Program Fourth Annual Summer Conference; p 145-151
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  • 2
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    Design of a lunar transportation system (1988)
    In:  CASI
    Details
    Publication Date: 2005-07-19
    Description: The establishment of lunar bases is the next logical step in the exploration of space. Permanent lunar bases will support scientific investigation, the industrialization of space, and the development of self-sufficiency on the Moon. Scientific investigation and research and development would lead to applications utilizing lunar material resources. By utilizing these resources, the industrialization of space can become a reality. The above two factors coupled with the development of key and enabling technologies would lead to achievement of self-sufficiency of the lunar base. Attention was focused on specific design(s) to be pursued during subsequent stages in advanced courses. Some of the objectives in the project included: (1) minimizing the transportation of construction material and fuel from earth, or maximizing the use of the lunar material; (2) use of novel materials and light weight structures; (3) use of new manufacturing methods and technology such as magnetically levitated, or superconducting materials; and (4) innovative concepts of effectively utilizing the exotic lunar conditions, i.e. high thermal gradients, lack of atmosphere, zero wind forces, and lower gravity, etc.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: USRA, NASA(USRA University Advanced Design Program Fourth Annual Summer Conference; p 89-92
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  • 3
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    Measurements of reflectance spectra of ion-bombarded ice and application to surfaces in the outer solar system (1988)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The first results of laboratory measurements of the wavelength dependence of the alternation of the visible reflectance of H2O ice irradiated by keV ions are presented. When the implanted species is chemically neutral, absorption is slightly enhanced below 0.55 micron. For an incident species containing sulfur, a strong absorption feature is produced at 0.4 micron, probably corresponding to S3. This occurs at too large a wavelength to account for the absorption feature observed at Europa by Voyager and therefore casts doubt on the recent interpretation of the reflectance data of Europa.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 333; 240
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  • 4
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    Surficial textures of the Galilean satellites (1988)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The observations of the Galilean satellites of Jupiter obtained with the IUE have been analyzed as a function of solar phase angle. By fitting the measurements to a shadowing model, comparative descriptions of the microtextures of the optically active portion of the surfaces of the satellites are derived. Important differences among the satellites and between leading and trailing hemispheres of individual satellites result from the different processes of meteoritic bombardment, magnetospheric interaction, and geological resurfacing that operate in the Jovian system. Io and Callisto have the most tenuous upper regoliths, whereas the surface of the leading side of Europa is the most compact.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 333; 148-151
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  • 5
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    A comparison of solar irradiances measured by SBUV, SME, and rockets (1988)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: In this paper, Solar Backscatter Ultraviolet (SBUV) measurements of solar irradiance and predictions from the Mg 280-nm index are compared with each other and with coincident Solar Mesosphere Explorer (SME) and rocket measurements. The SBUV irradiances show a systematic decrease with time not seen in the rocket measurements; a correction for this decrease is introduced. The scatter and overall structure in the SME spectra is 3-5 percent, of the order of or larger than most of the changes predicted by the Mg index. The corrected SBUV ratio and the Mg index prediction for it agree to within 1 percent. Such agreement supports a common origin for variations between solar maximum and minimum and those for individual rotations: the degree to which active regions cover the visible hemisphere of the sun.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 7091-710
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  • 6
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    Effect of solar proton events in 1978 and 1979 on the odd nitrogen abundance in the middle atmosphere (1988)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Daily average solar proton flux data for 1978 and 1979 are used in a proton energy degradation scheme to derive ion pair production rates and atomic nitrogen production rates. The latter are computed in a form suitable for inclusion in an atmopheric, two-dimensional, time-dependent photochemical model. Odd nitrogen distributions are computed from the model, including atomic nitrogen production from solar protons, and are compared with baseline distributions. The comparisons show that the average effect of the solar protons in 1978 and 1979 was to cause changes in odd nitrogen only above 10 mbar and at latitudes only above about 50 deg in both hemispheres. The influence of the solar proton-produced odd nitrogen on the local abundance of odd nitrogen depends primarily on the background odd nitrogen abundance as well as the altitude and season.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 7084-709
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  • 7
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    Thermal structure of the ionosphere of Mars - Simulations with one- and two-dimensional models (1988)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Heat flux saturation effects are included in the present one- and two-dimensional models of the Martian upper ionosphere's thermal structure. The inclusion of small upper boundary and volume heat sources is found to yield satisfactory simulations of the dayside ion temperature observation results obtained by Viking 1's retarding potential analyzers. It is noted that the plasma flow-transport of heat from the dayside to the nightside makes no contribution to the ion and electron temperatures that have been calculated for the nightside.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 74; 357-364
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  • 8
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    Non-seasonal changes in total column ozone from satellite observations, 1970-86 (1988)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Analyses of nonseasonal changes in total column ozone from satellite observations during the period 1970-86 suggest, when combined with analyses of Dobson network data, that the largest reduction in global ozone since 1959 occurred between 1978 and 1986. The existence of an Arctic region of enhanced ozone depletion with similar but less pronounced characteristics of the Antarctic region is described. Before 1983 large rates of decrease were confined to high latitudes, subsequently regions of large rates of ozone depletion have appeared at midlatitudes.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 332; 219-227
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  • 9
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    Mass extinctions, atmospheric sulphur and climatic warming at the K/T boundary (1988)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The possible climatic effects of a drastic decrease in cloud condensation nuclei (CCN) associated with a severe reduction in the global marine phytoplankton abundance are investigated. Calculations suggest that a reduction in CCN of more than 80 percent and the resulting decrease in marine cloud albedo could have produced a rapid global warming of 6 C or more. Oxygen isotope analyses of marine sediments from many parts of the world have been interpreted as indicating a marked warming coincident with the demise of calcareous nannoplankton at the K/T boundary. Decreased marine cloud albedo and resulting high sea surface temperatures could have been a factor in the maintenance of low productivity in the 'Strangelove Ocean' period following the K/T extinctions.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 332; 63-65
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  • 10
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    Extremely low N2O concentrations in the springtime stratosphere at McMurdo Station, Antarctica (1988)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Measurements have been made of stratospheric N2O using the Stony Brook millimeter-wave remote sensing spectrometer at McMurdo Station, and NO2 mixing ratios are found that are less than 1.5 at 20 km and less than 1.10 at 25 km compared to values measured during the Antarctic summer. The observed mixing ratios are also much less than those predicted by global-scale models of stratospheric chemistry and dynamics. As the NO2 signal remained very weak when McMurdo was at the edges of the ozone hole and showed no signs of recovering during October, it is concluded that the geographical and temporal extent of the region of low NO2 is comparable to or greater than that of the ozone hole. These results argue against theories that require springtime upwelling to explain the Antarctic ozone hole. It is suggested that the air in the Antarctic lower stratosphere during late winter and early spring has been subjected to considerable downward transport.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 332; 53-55
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  • 11
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    Deformational models of rifting and folding on Venus (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Features of presumed tectonic origin on Venus are reviewed, and lithospheric strength envelopes are derived based on laboratory measurements of the deformational properties of crustal and subcrustal rocks, extrapolated to conditions appropriate to Venus. Models for rifting and folding are developed that use this lithospheric structure and take into account both brittle and ductile yielding as well as finite elastic strength. For both rifting and folding, structures with characteristic widths and spacings are predicted whose size depends on the thickness of the lithosphere, density contrast, and elastic properties of the layer. Finally, the model predictions are compared with the widths and spacings of observed tectonic features, and it is concluded that they are consistent with a relatively strong mantle layer separated from a thin brittle surface layer by a ductile lower crust. These results allow constraints to be placed on the crustal thickness and thermal gradient on Venus.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 4759-477
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  • 12
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    Effect of computed horizontal diffusion coefficients on two-dimensional N2O model distributions (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The effects of horizontal diffusion coefficients K(yy) and K(yz), computed directly from the residual circulation, on the N2O distribution in a photochemical model were investigated, using a modified version of the two-dimensional model of Guthrie et al. (1984). The residual circulation was computed using the NMC's temperature data and the heating rates reported by Rosenfield et al. (1987). As compared with the effect of the residual circulation alone, the use of horizontal diffusion coefficients produced substantial changes in the N2O distribution and increased the N2O's lifetime values by a few percent. It is suggested that trace gases, such as CH4, CFCl3, CF2Cl2, CH3Cl, and CCl4, which impact the NO(x), HO(x), and Cl(x) radical distributions and therefore ozone, will be influenced in a similar manner by the addition of more realistic diffusion fields.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 5213-521
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  • 13
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    VLF noises triggered by whistlers as observed in the topside ionosphere (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: ISIS-1, ISIS-2, and DE-1 VLF electric field data from Kashima station, Japan are used to investigate characteristics of whistler triggered emissions in the topside ionosphere. The occurrence rate for nonducted whistler triggered emission is shown to be distributed randomly between L = 2.0 and 4.2, while the occurrence rate of ducted whistler triggered emissions increases with latitudes between L = 1.5 and 2.9, attains a maximum at L = 2.7, and abruptly drops off at L = 3.0. The findings indicate that some whistler triggered emissions may be generated by the interaction of whistlers with magnetospheric electrons.
    Keywords: GEOPHYSICS
    Type: Radio Research Laboratory, Journal (ISSN 0033-8001); 35; 15-26
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  • 14
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    Effect of a uniform sea-level change on the earth's rotation and gravitational field (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Global water redistriburtion between the oceans, atmosphere and continents causes changes in the earth's rotation and gravitational field. To conserve water mass, the effect of the small uniform change in sea-level must be considered. Explicit formulas are provided for these sea-level corrections to the gravitational Stokes coefficients, polar motion and length of day. In two recent publications, this sea-level correction term for polar motion was given incorrectly. These errors which arose from normalization conventions with the ocean function are corrected.
    Keywords: GEOPHYSICS
    Type: Geophysical Journal (ISSN 0952-4592); 93; 191-193
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  • 15
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    Comparison of SAGE II solar extinction data with airborne measurements of atmospheric backscattering in the troposphere and lower stratosphere (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: In April 1986, during passage of the SAGE I satellite, the first simultaneous measurements of the atmospheric backscattering coefficient beta (pi, 10.6 microns) were made with an airborne CO2 lidar. Individual ratios of beta and the SAGE II extinction sigma (1.02 micron) are in reasonable accord with previously calculated values. The trend with height shows a distinctly nonlinear relation, which is probably attributable to steadily changing size distributions of aerosols.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 332; 709-711
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  • 16
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    Balloon-borne measurements of middle atmosphere aerosols and trace gases in Antarctica (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: This paper reviews data on in situ balloon-borne measurements on stratospheric ozone concentrations and aerosol contents obtained prior to 1986, along with the measurements obtained in 1986 during the National Ozone Expedition. The data indicate that the phenomenon of ozone depletion appears to be shaped spatially and temporally by dynamical stratospheric phenomena. In terms of Antarctic stratospheric research, it appears that the most important problems at the moment involve delineating the springtime ozone depletion through accurate in situ measurements of temperature, trace gas, and particle size (in addition to remote sensing from space).
    Keywords: GEOPHYSICS
    Type: Reviews of Geophysics (ISSN 8755-1209); 26; 113-130
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  • 17
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    Evolution of a steam atmosphere during earth's accretion (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The evolution of an impact-generated steam atmosphere around an accreting earth is presently modeled under the assumption of Safronov (1978) accretion, in a scheme that encompasses the degassing of planetesimals on impact, thermal blanketing by the steam atmosphere, surface-to-interior water exchange, the shock heating and convective cooling of the earth's interior, and hydrogen escape due both to solar EUV-powered planetary wind and impact erosion. The model yields four distinct classes of impact-generated atmospheres: the first, on which emphasis is placed, has as its salient feature a molten surface that is maintained by the opacity of a massive water vapor atmosphere; the second occurs when the EUV-limited escape exceeds the impact degassing rate, while the third is dominated by impact erosion and the fourth is characterized by an atmosphere more massive than any thus far encountered.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 74; 62-97
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  • 18
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    On the origin of Venus' atmosphere - Possible contributions from simple component mixtures and fractionated solar wind (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: It is suggested that while an origin of the volatiles of the Venus atmosphere as a single, fractionated component derivable from the solar wind can account for Ar, Kr, and Xe relative abundances, it does so only with an excess of C, and perhaps of N. A similarity is noted in relative abundances between Venus volatiles and fractionated solar wind gases in the lunar regolith which implies that such a lunar-type component is a major contributor to Venus' volatiles. A variety of Venus atmosphere models is considered; these fail to explain the low Ne/Ar ratio on Venus.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 74; 3-20
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  • 19
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    A ground-based technique for millimeter wave spectroscopic observations of stratospheric trace constituents (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Recent concern over possible long term stratospheric changes caused by the introduction of man-made compounds has increased the need for instrumentation that can accurately measure stratospheric minor constituents. The technique of radio spectroscopy at millimeter wavelengths was first used to observe rotational transitions of stratospheric ozone nearly two decades ago, but has not been highly developed until recently. A ground-based observing technique is reported which employs a millimeter-wave superheterodyne receiver and multichannel filter spectrometer for measurements of stratospheric constituents that have peak volume mixing ratios that are less than 10 to the -9th, more than 3 orders of magnitude less than that for ozone. The technique is used for an extensive program of observations of stratospheric chlorine monoxide and also for observations of other stratospheric trace gases such as (O-16)3, vibrationally excited (O-16)3, (O-18)2(O-16), N2O, HO2, and HCN. In the present paper, analysis of the observing technique is given, including the method of calibration and analysis of sources of error. The technique is found to be a reliable means of observing and monitoring important stratospheric trace constituents.
    Keywords: GEOPHYSICS
    Type: Radio Science (ISSN 0048-6604); 23; 106-118
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  • 20
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    Comment on 'A new method of forecasting geomagnetic activity and proton showers' by A. Hewish and P.J. Duffet-Smith (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science (ISSN 0032-0633); 36; 205
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  • 21
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    Magnetic clouds, geomagnetic disturbances, and cosmic ray decreases (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Nineteen magnetic clouds are identified in the years from 1978 through 1982 and studied using superposed epoch analysis. The magnetic-field intensity, proton density and proton temperature are enhanced ahead of magnetic clouds that are preceded by shock, while strong magnetic-field intensity and low proton temperature are observed within the clouds. A relatively large (about 2.5 percent) decrease in cosmic-ray intensity is associated with magnetic clouds that are preceded by a shock, perhaps caused by the turbulent sheath behind an interplanetary shock ahead of the magnetic cloud, whereas only a small (0.5 percent) decrease in intensity is associated with the magnetic cloud itself. Magnetic clouds can produce geomagnetic activity with a decrease in Dst index of the order 100 gamma. The magnitude of the change in the Dst index for the case when southward fields arrive first is comparable to that for the case when northward fields arrive first, and the phase is such that geomagnetic activity is associated with southward fields.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 2511-251
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  • 22
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    Source of the Australasian tektite strewn field - A possible off-shore impact site (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Although there is a preponderance of evidence that tektites were formed by asteroid impacts on the earth, no source crater has been found for the largest and youngest of the strewn fields - the Austalasian strewn field. A combined Seasat/Geos 3 altimeter data set of sea surface heights in the northern portion of the Australasian strewn field has been examined for negative gravity anomalies on the continental shelf and slope which might be related to the source crater for these tektites. A large negative anomaly called the Qui Nhon Slope Anomaly is a sea surface depression of approximately 1.5 meters over an area of 100 km diameter. It corresponds to a gravity anomaly of about -50 mgal. It is proposed that this anomaly may be due to the impact structure that produced the Australasian strewn field.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 15; 357-360
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  • 23
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    The solar wind control of Jupiter's broad-band kilometric radio emission (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Observations of the solar wind close to Jupiter are compared with the broad-band kilometric radio emission (bKOM), using data recorded by Voyager 1 and Voyager 2 during 1979. The lower bKOM frequencies, less than about 300 kHz, are found to correlate with the solar wind density and pressure and with the interplanetary magnetic field (IMF) magnitude during periods when there is a well-defined magnetic sector structure. The results suggest that lower frequency bKOM events are most likely to occur after a sector boundary has passed Jupiter during the period when the solar wind density and the IMF magnitude are increasing towards the sector center. The average bKOM energy per Jovian rotation tends to have lower values soon after the sector center has passed. Higher-frequency/higher-energy bKOM emission may be contaminated by hectometric emission (HOM) and differently correlated with solar activity. The solar wind control may also be obscured by some stronger control. It is suggested that electron density fluctuations in the Io torus, where the source is believed to be located, may be responsible for variations in the beaming and hence variations in the observed emission.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 192; 1-2,; 354-359
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  • 24
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    Diurnal variation of nitric oxide at 32 km - Measurements and interpretation (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Balloon observations of NO and ozone near sunset and sunrise around 32 km were made on September 19 and October 4, 1985 from Aire sur l'Adour, France. The NO concentration built up rapidly after sunrise, remained fairly steady during the day, and decreased slowly near sunset. This variation is interpreted quantitatively in terms of current photochemistry in relation to ozone.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 2451-546
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  • 25
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    Large impact basins and the mega-impact origin for the crustal dichotomy on Mars (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The hypothesis that the crustal dichotomy on Mars is due to a single giant (mega) impact early in Martian history is tested by determining the number of 'missing' basins, the difference between the observed number of large impact basins on Mars and the number expected from a 1/D-squared distribution. If the Borealis Basin was the largest member of a 1/D-squared impact population, a large number of 'missing' basins is expected which is too large to be hidden by the younger surface units. If Chryse is the largest member of a 1/D-squared impact population, the more modest number of 'missing' basins could be confined to areas of Mars that have been resurfaced or reworked by subsequent geologic processes.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 15; 229-232
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  • 26
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    Thermal emission from Saturn's rings at 380 microns (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Two different techniques have been used to derive the Saturn disk's ring brightness temperatures from 380-micron observations: (1) comparisons of these wide-beam observation disk-ring system results with those obtained for an earlier epoch, when the rings were edge-on, then differencing the two measurements to obtain a value for the rings' contribution; and (2) ring contribution resolution during scanning along the disk-ring plane, to yield a B-ring brightness temperature of 39 + or - 8 K at 380 microns. The results obtained indicate a gradual decrease of observed ring brightness temperature from the IR to the radio wavelength range.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 574-583
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  • 27
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    Effect of line mixing on atmospheric brightness temperatures near 15 microns (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The effect of line mixing on the effective blackbody brightness temperature of the earth in the region of the 15-micron nu 2 Q branch of CO2 is calculated. The procedures used to compute line mixing follow those used to successfully model mixing observed in laboratory spectra of two near-infrared CO2 Q branches. The atmospheric radiances are calculated between 664 and 670/cm, a spectral region that is of interest for sounding the upper troposphere and the stratosphere. Mixing was found to lower the observed brightness temperatures by as much as 3 K for some temperature profiles. Ignoring this effect would significantly impact the ability of advanced sounders to produce temperature retrievals which meet the projected accuracy requirement of 1 K/km.
    Keywords: GEOPHYSICS
    Type: Applied Optics (ISSN 0003-6935); 27; 872-878
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  • 28
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    Superposed ridges of the Hesperia Planum area on Mars (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Mare ridges of the Hesperia Planum area form linear, reticular and circular structures. The main factors effective in mare ridge formation have been: (1) a large areal, or maybe even global, shortening and compression, (2) major crustal tectonics, and (3) the moderation of tectonic movements by the megaregolith discontinuity layer(s) between surface lavas and the bedrock leaving the compressional thrust to dominate over other fault movements in surface tectonics.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth, Moon, and Planets (ISSN 0167-9295); 40; 71-99
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    F region electron temperature signatures of the plasmapause based on Dynamics Explorer 1 and 2 measurements (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A large DE 1 and 2 database covering all local times is used to explore the relationship between electron temperature (Te) signatures in the F region and plamaspheric density structures. The quiet time Te signature remains in the vicinity of 60 deg invariant latitude at all local times, while the plasmapause is found to bulge to about 60 deg at 1500 LT. The plasmasphere in the bulge region is shown to exhibit an internal feature in the vicinity of 60 deg which takes the form of a sharp H(+) gradient. It is suggested that the light-ion gradient may represent a recently created sharp boundary between an old plasmasphere and a new plasmasphere. The present Te characteristics are consisent with plasmasphere depletion and refilling time constants.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1896-190
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  • 30
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    Low-energy bouncing ions in the magnetosphere - A three-dimensional numerical study of Dynamics Explorer 1 data (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1859-187
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  • 31
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    Analysis of Pioneer Venus Orbiter ultraviolet spectrometer Lyman alpha data from near the subsolar region (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Pioneer Venus Orbiter ultraviolet spectrometer data from 20 orbits which span 3 years have been analyzed to determine the atomic hydrogen number density and vertical flux at the exobase as a function of solar zenith angle, F(10.7) index, and spacecraft latitude. From 1979 through 1981, the exobase number density n(c) and flux phi(c) are remarkably constant at n(c) = 6.0 + or - 1.5 x 10 to the 4th/cu cm and phi(e) = 7.5 + or - 1.5 x 10 to the 7th/sq cm per s in the subsolar region. The integrated vertical column density above 110 km is 3.6 + or - 1 x 10 to the 13th/sq cm. An empirical relationship is determined between the line center solar flux at H Lyman alpha, piF(0), and the F(10.7) index.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1766-177
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  • 32
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    First Viking results - Magnetic field measurements (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The magnetic field experiment on the Swedish Viking satellite consists of a triaxial fluxgate magnetometer system with the sensors mounted on a 2-m boom. Transverse magnetic field perturbations are readily observed which identify the large-scale auroral and cusp-region Birkeland current (BC) systems. A sharp gradient was observed in the dayside region near apogee and 08:40 MLT during a pass on March 25, 1986 which has been interpreted as an earthward-flowing BC of 8 micro-A/sq m. When projected to ionospheric altitudes it is estimated that the current density is 200 micro-A/sq m.
    Keywords: GEOPHYSICS
    Type: Physica Scripta (ISSN 0031-8949); 37; 3, Ma; 479-481
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  • 33
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    Voyager at Uranus (1988)
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    Publication Date: 2011-08-19
    Description: The findings made in the Voyager flyby past Uranus are reviewed. The spacecraft is described, and the preparations for the Uranus encounter are recalled. The encounter characteristics are presented, and the characteristics of the Uranian atmosphere and interior, magnetic field, rings, and satellites are discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: (ISSN 0007-084X); 41; 49-62
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  • 34
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    Trace gas emissions from a mid-latitude prescribed chaparral fire (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Smoke-plume gas samples were collected at altitudes from 35-670 m above the ground over the San Dimas Experimental Forest during a 400-acre prescribed chaparral fire. Mean emission ratios relative to CO2 for CO, H2, CH4, and total nonmethane hydrocarbons were lower than previous values obtained for large biomass-burning field experiments. Comparison of samples from vigorously flaming and mixed stages of combustion revealed little differences in CO2 normalized emission ratios for these gases (except for N2O).
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1653-165
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  • 35
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    Measurements of odd nitrogen compounds in the stratosphere by the ATMOS experiment on Spacelab 3 (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Spacelab 3's Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment has obtained 30 deg N and 48 deg S vertical profiles of reservoir gases, source gases, and other trace molecules that are important in the middle atmosphere's odd nitrogen, odd chlorine, and odd hydrogen chemical families. The abundances of individual gases and total odd nitrogen levels measured by ATMOS have been compared with prior results obtained from balloon and satellite platforms. The lower-limit profile agrees with ATMOS data to within 16 percent up to 42 km altitude.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1718-173
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  • 36
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    Measurements of atmospheric hydrocarbons and biogenic emission fluxes in the Amazon boundary layer (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Tropospheric mixing ratios of methane, C2-C10 hydrocarbons, and carbon monoxide were measured over the Amazon tropical forest near Manaus, Amazonas, Brazil, in July and August 1985. The measurements, consisting mostly of altitude profiles of these gases, were all made within the atmospheric boundary layer up to an altitude of 1000 m above ground level. Data characterize the diurnal hydrocarbon composition of the boundary layer. Biogenic emissions of isoprene control hydroxyl radical concentrations over the forest. Biogenic emission fluxes of isoprene and terpenes are estimated to be 25,000 micrograms/sq m per day and 5600 micrograms/sq m per day, respectively. This isoprene emission is equivalent to 2 percent of the net primary productivity of the tropical forest. Atmospheric oxidation of biogenic isoprene and terpenes emissions from the Amazon forest may account for daily increases of 8-13 ppb for carbon monoxide in the planetary boundary layer.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1407-141
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  • 37
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    Neptune radio emission - Predictions based on planetary scaling laws (1988)
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    Publication Date: 2011-08-19
    Description: In this paper a prediction is advanced concerning Neptune's low-frequency radio emission based on the radiometric Bode's law for radio planets in combination with the magnetostrophic scaling law for magnetized planets. The total emitted radio power is predicted to be about 1.6 x 10 to the 7th W, very nearly the same as that predicted and observed for Uranus. Possible emission spectral shapes, based on Saturn and earth-like models, are shown. Using these models, the radio emission frequency range is predicted to extend from approximately 100 to just over 1000 kHz, with a spectral peak between 350 and 500 kHz. If radiation is beamed approximately in the sunward direction, Neptune should be detectable by the planetary radio astronomy experiment onboard the Voyager spacecraft sometime between 45 and 90 days before closest approach. This detection is likely to represent the first direct evidence of a Neptune magnetic field. Possible implications for Neptune's magnetosphere with regard to the time of first detection are discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 15; 114-1117
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  • 38
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    Nonlinear evolution of the Kelvin-Helmholtz instability in the high-latitude ionosphere (1988)
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    Publication Date: 2011-08-19
    Description: The first numerical simulations of the nonlinear evolution of the electrostatic Kelvin-Helmholtz (K-H) instability with ionospheric Perderson conductivity coupling are presented. It is found that the K-H instability develops in a distinctly different manner in the nonlinear regime with Pedersen coupling than without it. Pedersen coupling effects, in conjunction with a neutral wind and density gradient, are shown to result in an increased time scale for K-H instability wave growth, to inhibit K-H vortex formation, to lead to nonlinear structures which can be described as 'breaking waves', and to generate, in the nonlinear regime, small-scale turbulence by means of secondary instabilities growing on primary waves. The spatial power spectra of the electrostatic potential and density fluctuations are computed, and differences with and without Pedersen effects are reported.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 137-152
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  • 39
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    High resolution images of Venus from ground-based radar (1988)
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    Publication Date: 2011-08-19
    Description: The Goldstone Deep Space Station ground-based synthetic aperture radar system has been used to obtain radar images of Venus with resolutions of close to 1.3 km. Observations were made at 12.5 cm wavelength using circular polarization. From 12 days of observations during the 1986 inferior conjunction, three images have been selected for initial processing. The images show remarkable surface features including craters, ridges, and regions of high Fresnel reflectivity in the plains region.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 15; 577-580
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  • 40
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    The role of molecular hydrogen and methane oxidation in the water vapour budget of the stratosphere (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The detailed photochemistry of methane oxidation has been studied in a coupled chemical/dynamical model of the middle atmosphere. The photochemistry of formaldehyde plays an important role in determining the production of water vapor from methane oxidation. At high latitudes, the production and transport of molecular hydrogen is particularly important in determining the water vapor distribution. It is shown that the ratio of the methane vertical gradient to the water vapor vertical gradient at any particular latitude should not be expected to be precisely 2, due both to photochemical and dynamical effects. Modeled H2O profiles are compared with measurements from the Limb Infrared Monitor of the Stratosphere (LIMS) experiment at various latitudes. Molecular hydrogen is shown to be responsible for the formation of a secondary maximum displayed by the model water vapor profiles in high latitude summer, a feature also found in the LIMS data.
    Keywords: GEOPHYSICS
    Type: Royal Meteorological Society, Quarterly Journal (ISSN 0035-9009); 114; 281-295
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  • 41
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    ISEE-3 observations of the earth's radio continuum through the bow shock and magnetosheath and in the magnetosphere (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: On October 1 1983, ISEE-3 crossed the earth's bow shock several times and entered the magnetosphere while continuously recording the nonthermal continuum (NTC) radio emission which is generated inside the magnetosphere. The effects of the solar wind, the bow shock, the magnetosheath, and the magnetopause on the propagation of the NTC are studied. On that day it is found that: (1) the relative values of the NTC low frequency cut-off in the solar wind and in the magnetosheath is due to an unusually high density overshoot in the bow shock, 7 to 11 times the solar wind density; (2) refraction at the interface between the magnetosheath and the solar wind can explain most of the decrease in the source angular size when the observer travels away from the earth; (3) plasma density irregularities in the magnetosheath cause considerable scattering of the NTC, and this effect gives a large apparent size to the NTC source when observed from inside the magnetosheath; and (4) the apparent source is also relatively large inside the magnetosphere, probably due to an approach to ray isotropy caused by oblique reflections from the magnetopause.
    Keywords: GEOPHYSICS
    Type: Annales Geophysicae (ISSN 0980-8752); 6; 309-318
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  • 42
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    New evidence from the South China Sea for an abrupt termination of the last glacial period (1988)
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    Publication Date: 2011-08-19
    Description: Results demonstrating an abrupt change in the rate and character of sedimentation in the South China Sea at the close of the last glacial period are presented. Radiocarbon dating and its position in the oxygen isotope shift suggest that this change may be coincident with the abrupt change in climatic conditions seen at high latitudes in the North Atlantic and the Antarctic at 13 kyr BP. These results support the contention that a major global climatic change occurred between 14 and 13 kyr BP.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 333; 156-158
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  • 43
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    Comparison of OGO 6 measured thermospheric temperatures with the MSIS-86 empirical model (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The thermospheric temperatures measured by the Fabry-Perod interferometer on the OGO 6 satellite are found to be reasonably represented by the mass spectrometer/incoherent scatter 1986 (MSIS-86) empirical model except for two anomalies, one in the South Atlantic and the other near noon local time. These anomalies are likely due to measurement problems. The OGO 6 temperature data were not used in the generation the MSIS models, so this is an independent comparison of measured and model temperatures. The measurements were made primarily during daytime at mid to low latitudes and throughout the day at high latitudes. On average, the measured temperatures are 16 K below the MSIS-86 model temperatures. Latitude gradients during solstices as well as for the yearly average are well represented by the model, as are high-latitude longitudinal and magnetic activity variations.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 5965-597
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  • 44
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    High-temperature shock formation of N2 and organics on primordial Titan (1988)
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    Publication Date: 2011-08-19
    Description: Theoretical models suggest that the initial form of nitrogen in Titan's atmosphere may have been NH3. The possible importance of strong shocks produced during high-velocity impacts accompanying the late stages of accretion are investigated as a method for converting NH3 to N2, of which Titan's atmosphere is now primarily composed. The focused beam of a high-power laser is used to simulate the effects of an impact in Titan's atmosphere. For mixtures of 10, 50, and 90 percent NH3, yields of 0.25, 1, and 6 x 20 to the 17th molecules of N2 per joule, respectively, were obtained. It is also found that the yield of HCN is comparable to that for N2. Several other hydrocarbons are produced, many with yields in excess of theoretical high-temperature-equilibrium models. The above yields, when combined with models of the satellite's accretion, result in a total N2 production comparable to that present in TItan's atmosphere and putative ocean.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 332; 520-522
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  • 45
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    Charged particle depletion surrounding Saturn's F ring - Evidence for a moonlet belt? (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An improved model of the Saturn magnetosphere and of the locations of known moons and rings is invoked in the present reconsideration of Pioneer 11 observations of five abrupt depletions in the flux of trapped magnetospheric electrons within a 2000-km-wide band around the F ring. It is inferred that the observed depletions of charged particles are caused by clumps of material with low optical depth; it is further hypothesized that these clumps are composed of regolith ejecta, are generated by collisions occurring within a belt of unseen, moonlet-scale (or smaller) objects occupying the entire radial region between Pandora and Prometheus. Attention is given to a self-consistent scenario in which these debris clouds are created, longitudinally spread, swept up onto belt object surfaces, and then thrown off by a subsequent collision.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 74; 284-324
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  • 46
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    Planetographic clustering of low-altitude impulsive electric signals in the night ionosphere of Venus (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: This paper presents maps of the locations of electromagnetic signals, presumably caused by lightning, which were observed at 730 Hz during the first three nighttime observing seasons of Pioneer Venus Orbiter when the spacecraft reached altitudes low enough to detect the signals. The maps show that there are specific 'active regions' of enhanced signal occurrence, and that at least some of these active regions appear to remain fixed in planetographic coordinates from year to year.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 331; 591-594
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  • 47
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    Observation of an ionospheric disturbance caused by a gamma-ray burst (1988)
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    Publication Date: 2011-08-19
    Description: A first observation of an ionospheric disturbance from a gamma-ray burst is reported. The burst, GB30801, occurred at 22:14:18 UT on August 1, 1983, and was one of the strongest ever observed. The total fluence was 0.002 erg/sq cm, most of which occurred in the first 4 s of the burst. Simultaneously, a change was observed in the amplitude of a VLF radio signal from a transmitter in Rugby, England indicative of an ionospheric disturbance. Weaker disturbances were also recorded at the same receiving site on signals from VLF stations in Annapolis, Maryland and Lualualei, Hawaii. The times of the burst and the disturbances are coincident within the 10-s resolution of the VLF recording system. No similar disturbances were observed within 60 hr around the time of the burst. In the future, a network of VLF burst monitors may provide measurements of the total ionizing energy fluence from a burst, as well as some limited directional information.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 331; 418-420
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    'Domestic' origin of opaque assemblages in refractory inclusions in meteorites (1988)
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    Publication Date: 2011-08-19
    Description: Experimental studies indicate that opaque assemblages rich in refractory siderophile elements were formed within host calcium- and aluminum-rich inclusions (CAIs) by exsolution, oxidation and sulphidization of homogeneous alloys, rather than by aggregation of materials in the solar nebula before the formation of CAIs. These opaque assemblages are thus not the oldest known solid materials, as was once thought, and they do not constrain processes in the early solar nebula before CAI formation. Instead, the assemblages record the changing oxygen fugacity experienced by CAIs during slow cooling in nebular and/or planetary environments.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 331; 405-409
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  • 49
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    Gravity domains and assembly of the North American continent by collisional tectonics (1988)
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    Publication Date: 2011-08-19
    Description: A gravity trend map of North America, based on a horizontal Bouguer gravity gradient map produced from gravity data for Canada and the conterminous United States, is presented and used to define a continental mosaic of gravity trend domains akin to structural domains. Contrasting trend characteristics at gravity domain boundaries support the concept of outward growth of the continent primarily by accretionary tectonics. Gravity patterns, however, indicate a different style of tectonics dominated in the development of now-buried Proterozoic orogenic belts in the south-central United States, supporting a view that these belts formed along the leading edge of a southward-migrating Proterozoic continental margin.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 331; 333
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  • 50
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    Atmospheric ozone at South Pole, Antarctica, in 1986 (1988)
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    Publication Date: 2011-08-19
    Description: Results of NOAA's measurements of the ozone vertical distributions at the South Pole and of the annual course of total ozone, conducted in 1986 with balloon-borne electrochemical concentration cell (ECC) ozonesondes and a Dobson spectrophotometer, are described. The major finding was that the stratospheric ozone decreases abruptly between September 20 and October 15, with the bulk decrease occurring between 12 and 21 km. In this period, the column ozone and ozone volume mixing ratio at 16 km (the altitude of the normal ozone maximum at South Pole) decreased by 78 percent, and column ozone between 12 and 21 km decreased by 50 percent. The results of these measurements are compared with data obtained in 1971, and the changes observed in the ozone vertical distributions and in the temporal variations of atmospheric ozone are discussed.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 5167-518
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    Simultaneous measurement of minor stratospheric constituents with emission far-infrared spectroscopy (1988)
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    Publication Date: 2011-08-19
    Description: The vertical mixing ratio profiles of H2O, HDO, O3, heavy ozone, HF, HCl, HCN, and OH in the stratosphere are retrieved from high-resolution far-infrared emission spectra. These spectra were obtained with a balloon-borne Fourier transform spectrometer in the spring of 1979 at 32 deg N. The nonlinear least squares fit method is used in the analysis. The results are obtained relative to the O2 mixing ratio, whose emission features can be found in the same spectra. The retrieval of OH together with other species should be particularly significant for the study of upper stratospheric photochemistry, although the errors are relatively large: 28 percent for OH and 16-19 percent for other species.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 3851-386
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    Antarctic springtime ozone depletion computed from temperature observations (1988)
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    Publication Date: 2011-08-19
    Description: An observationally based, mechanistic dynamical model is used to simulate the decline of total ozone during September and October for the years 1979 through 1986. Vertical velocities derived from observed stratospheric temperature changes and computed radiative heating rates are used to advect an ozone mixing ratio profile during the Antarctic spring period. An early August 1982 Syowa balloonsonde ozone profile is used to initialize the computations. The model reasonably simulates the September and October changes in total ozone, considering the uncertainties in the observed data and the radiative heating. The simulated decline is found to be very sensitive to the choice of initial ozone profile and to small changes in the radiative heating. The results of this study suggest that the dynamical hypothesis of the Antarctic ozone depletion is both quantitatively credible and consistent with the observed temperature changes.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 3833-384
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    Resonant geomagnetic field oscillations and Birkeland currents in the morning sector (1988)
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    Publication Date: 2011-08-19
    Description: The relationship between large-scale Birkeland currents and resonant oscillations of the geomagnetic field is investigated on the basis of Viking magnetic-field, electric-field, and particle measurements and AMPTE-CEE and IMP-8 magnetic-field measurements obtained during April 23-25, 1986. The data are presented in extensive graphs and characterized in detail. The 3-16-mHz 5-60-nT magnetic-field oscillations detected by Viking are also seen by AMPTE-CEE below L = 8.8 and extend from the lower L shells to the boundary between regions 1 and 2 of the Birkeland-current system, and this boundary is shown to be closely related to the interface between the low-latitude boundary layer and the central plasma sheet. It is suggested that the magnetospheric oscillations may be driven by several different solar-wind features, possibly depending on the direction of the IMF.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 2661-267
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  • 54
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    A few parts in 10 to the 8th geodetic baseline repeatablity in the Gulf of California using the Global Positioning System (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: GPS geodetic measurements of 350-650 km baselines across the Pacific-North America plate boundary in the Gulf of California are presented. The analysis employs a four-station U.S. fiducial network and combined carrier phase and pseudorange data. Water vapor radiometer data at the Gulf sites are used to calibrate the GPS signal for wet tropospheric path delays. Residual tropospheric delays are modeled as first-order exponentially correlated stochastic processes. The measurement precision for horizontal components is a few parts in 10 to the 8th or better.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 15; 353-356
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  • 55
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    Iridium abundance maxima in the Upper Cenomanian extinction interval (1988)
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    Publication Date: 2011-08-19
    Description: Two iridium abundance peaks, both 0.11 ppb (whole-rock basis) over a local background of 0.017 ppb, have been found in Middle Cretaceous marine rocks near Pueblo, Colorado. They occur just below the 92-million-year-old Cenomanian-Turonian (C-T) stage boundary. No other peaks were found in 45 meters of strata (about 2.5 million years of deposition) above and below the boundary interval. The broad lower peak straddles the first in a series of extinctions of benthic and nektonic macrobiota which comprise the C-T extinction event. The sharp upper peak occurs stratigraphically about 1.2 meters above the lower peak. The excess Ir might be from meteoroid impacts.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 15; 346-349
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    Boundary layer ozone - An airborne survey above the Amazon Basin (1988)
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    Publication Date: 2011-08-19
    Description: Ozone data obtained over the forest canopy of the Amazon Basin during July and August 1985 in the course of NASA's Amazon Boundary Layer Experiment 2A are discussed, and ozone profiles obtained during flights from Belem to Tabatinga, Brazil, are analyzed to determine any cross-basin effects. The analyses of ozone data indicate that the mixed layer of the Amazon Basin, for the conditions of undisturbed meteorology and in the absence of biomass burning, is a significant sink for tropospheric ozone. As the coast is approached, marine influences are noted at about 300 km inland, and a transition from a forest-controlled mixed layer to a marine-controlled mixed layer is noted.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1452-146
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    Tropospheric nitric oxide measurements over the Amazon Basin (1988)
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    Publication Date: 2011-08-19
    Description: Horizontal and vertical distributions of nitric oxide (NO) were measured over the Amazon Basin during NASA's Global Tropospheric Experiment (GTE) Amazon Boundary Layer Experiment mission in July-August 1985. During transit flights between the Virginia coast and Manaus, Brazil, NO mixing ratios were 12-15 pptv at 5 km altitude. Values up to 200 pptv were observed in electrically active clouds. During longitudinal surveys over the Amazon region, NO mixing ratios in the lower planetary boundary layer decreased from 25-60 pptv over the central basin to 10-12 pptv in coastal regions. In the convective cloud layer or free troposphere, NO mixing ratios averaged 13 pptv in regions not influenced by biomass burning. No longitudinal trend above the mixed layer could be detected. A steep negative gradient with increasing altitude was noted within the mixed layer before midday. Mixing ratios decreased from 60 pptv at 0.2 km to about 15 pptv at the top of the mixed layer (1 km). By midday, growth of the mixed layer height and enhanced mixing reduced the gradient, and evidence for mixing of NO into the convective cloud layer was noted.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1396-140
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    Tropospheric ozone and aerosol distributions across the Amazon Basin (1988)
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    Publication Date: 2011-08-19
    Description: As a part of the NASA Global Tropospheric Experiment to study the Amazon boundary layer, ozone and aerosol distributions were made measured in July-August 1985 by a NASA Electra aircraft on several long-range flights spanning different areas between Tabatinga and Belem, Brazil. Both positive and negative correlations were found in PBL between aerosol concentrations and O3 mixing ratios. The negative correlations result from the downward transport of relatively clean O3-rich air from the upper troposphere into PBL (which normally has higher aerosol loading and lower O3 concentrations than troposphere); positive correlations are found in biomass-burning plumes, where the aerosols are emitted into the air and O3 is photochemically produced. It was found that, in the dry season, a significant portion of the ozone over the rain forest is a result of biomass burning and that the distribution of photochemically produced O3 is strongly affected by synoptic-scale transport from large fires to the south/southeast.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1431-145
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    Structure and growth of the mixing layer over the Amazonian rain forest (1988)
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    Publication Date: 2011-08-19
    Description: The structure and growth of the atmospheric mixed layer over the Amazonian rain forest were examined using measurements obtained during the NASA Amazon Boundary Layer Experiment. Measurements of temperature, moisture, and horizontal wind were carried out in and above the mixed layer by means of a tethered balloon, rawinsonde, and aircraft; fluxes of sensible and latent heat were measured at the top of the canopy. It was found that the mixing layer grows rapidly, at 5-8 cm/sec, soon after sunrise to a mean maximum height of 1200 m by 1300 LT; during undisturbed conditions, mixed layer heights of 1000 are common between 1000 and 1600 LT. No horizontal inhomogeneities in the mixed layer structure or depth were found over large distances. A simple mixed layer model was applied to show how fluxes of species might be estimated using only quantities measured at the surface and prescribing an initial condition and boundary condition for the mixed layer.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1361-137
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    Antarctic ozone - Meteoric control of HNO3 (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Atmospheric circulation leads to an accumulation of debris from meteors in the Antarctic stratosphere at the beginning of austral spring. The major component of meteoric material is alkaline, comprised predominantly of the oxides of magnesium and iron. These metals may neutralize the natural acidity of stratospheric aerosols, remove nitric acid from the gas phase, and bond it as metal nitrates in the aerosol phase. Removal of nitric acid vapor has been previously shown to be a critical link in the photochemical depletion of ozone in the Antarctic spring, by allowing for increased catalytic loss from chlorine and bromine.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 15; 1-4
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  • 61
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    Measurements of air-broadened and nitrogen-broadened Lorentz width coefficients and pressure shift coefficients in the nu4 and nu2 bands of C-12H4 (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Air-broadened and N2-broadened halfwidth and pressure shift coefficients of 294 transitions in the nu4 and nu2 bands of C-12H4 have been measured from laboratory absorption spectra recorded at room temperature with the Fourier transform spectrometer in the McMath solar telescope facility of the National Solar Observatory. Total pressures of up to 551 Torr were employed with absorption paths of 5-150 cm, CH4 volume mixing ratios of 2.6 percent or less, and resolutions of 0.005 and 0.01/cm. A nonlinear least-squares spectral fitting technique has been utilized in the analysis of the twenty-five measured spectra. Lines up to J double-prime = 18 in the nu4 band and J double-prime = 15 in the nu2 band have been analyzed.
    Keywords: GEOPHYSICS
    Type: Applied Optics (ISSN 0003-6935); 27; 631-651
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    On the possible role of the reaction O + HO2 - OH + O2 in OH airglow (1988)
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    Publication Date: 2011-08-19
    Description: Experimental data on the so-called 'perhydroxyl' reaction O + HO2 - OH + O2 by which vibrationally excited OH is produced in the upper atmosphere are briefly reviewed. Both isotopic labeling studies and studies on the temperature dependence of the rate constant and the possible importance of its inverse are considered. The implication of the results for analysis of OH airglow data are emphasized. Some additional results on the dynamics of reactions related to OH airglow which may affect interpretation of OH emission measurements are summarized.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 285-288
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    Ground-level detection of low- and medium-frequency auroral radio emissions (1988)
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    Publication Date: 2011-08-19
    Description: Natural radio emissions in the frequency range of several hundred kHz were detected at ground level in the auroral region during a ground-level observing program conducted near Fairbanks, Alaska in the spring of 1986 in an attempt to detect auroral cyclotron-maser-generated whistler modes. Most of the strongest emissions were observed in a small time interval around midnight magnetic local time, suggesting a close tie-in with auroral processes. The results support earlier reports of radio noise from the aurora at frequencies of about 100 kHz and indicate the importance of extending the upper frequency of ground-based high-latitude VLF stations to the vicinity of 1 MHz.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 277-283
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    Are there carbonate deposits in the Valles Marineris, Mars? (1988)
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    Publication Date: 2011-08-19
    Description: The precipitation of 30 mbar of Martian atmosphere CO2 as carbonates in lakes is suggested to be the source of thick sequences of layered deposits found in the Valles Marineris. Support is adduced for this scenario from processes occurring in the perennially frozen dry valley lakes of Antarctica, where the lake water is supersaturated with atmospheric gases. Atmospheric CO2 would have accumulated in such Martian lakes as temperatures fell, and the presence of an insulating ice cover would have allowed liquid water to exist.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 73; 142-148
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    Interactions of planetesimals with protoplanetary atmospheres (1988)
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    Publication Date: 2011-08-19
    Description: The 'core instability' mechanism presently postulated for the interaction of planetesimals with the envelopes of growing giant planets involves core growth through the accretion of solid bodies in the solar nebula; the core thereby becomes more effective in the gravitational attraction of gas from the surrounding nebula into an envelope, until a runaway accretion stage is reached. Two-body trajectory curves of planetesimals through this envelope are computed which demonstrate the depth of penetration and the cross-sections for capture of icy and rocky planetesimals.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 73; 163-179
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    How climate evolved on the terrestrial planets (1988)
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    Publication Date: 2011-08-19
    Description: It is argued that the difference in the climates of Venus, earth, and Mars is due largely to differences in their ability to cycle CO2 between the crust and atmosphere. It is suggested that the earth has always had a moderate climate primarily because its cycling mechanism increases the amount of CO2 in the atmosphere when the surface of the planet cools and reduces the amount when the ground temperature rises. Mars is now frozen because it has lost the ability to cycle the gas back into its atmosphere, and Venus is a hothouse because it has no way of removing CO2 from its atmosphere.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Scientific American (ISSN 0036-8733); 258; 90-97
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    The Antarctic ozone hole (1988)
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    Publication Date: 2011-08-19
    Description: Observations of Antarctic ozone levels and the discovery of a hole in the Antarctic region are examined. The effects of chlorofluorocarbons (CFCs) on the level of stratospheric ozone are analyzed. Three cycles explaining the cause of ozone depletion in the poles are proposed. A comparison of field data and proposed depletion cycles reveals that the chemical origin of the ozone hole is due to CFCs. The potential global effects of the Antarctic ozone hole are discussed.
    Keywords: GEOPHYSICS
    Type: Oceanus (ISSN 0029-8182); 31; 47-52
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    The tectonics of Mercury (1988)
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    Publication Date: 2011-08-19
    Description: The probable tectonic history of Mercury and the relative sequence of events are discussed on the basis of data collected by the Mariner-10 spacecraft. Results indicate that Mercury's tectonic activity was confined to its early history; its endogenic activity was principally due to a small change in the shape of its lithosphere, caused by tidal despinning, and a small change in area caused by shrinkage due to cooling. Exogenic processes, in particular the impact activity, have produced more abundant tectonic features. Many features associated with the Caloris basin are due to loading of Mercury's thick lithosphere by extrusive lavas or subsidence due to magma withdrawal. It is emphasized that tectonic features observed on Mercury yield insight into the earliest tectonic events on planets like Mars and, perhaps, the earth, where subsequent events obscured or erased the most ancient tectonic records.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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    Surface composition of Mercury from reflectance spectrophotometry (1988)
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    Publication Date: 2011-08-19
    Description: The controversies surrounding the existing spectra of Mercury are discussed together with the various implications for interpretations of Mercury's surface composition. Special attention is given to the basic procedure used for reducing reflectance spectrophotometry data, the factors that must be accounted for in the reduction of these data, and the methodology for defining the portion of the surface contributing the greatest amount of light to an individual spectrum. The application of these methodologies to Mercury's spectra is presented.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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    Tersail - A numerical model for combined analysis of vegetation canopy bidirectional reflectance and thermal emissions (1988)
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    Publication Date: 2011-08-19
    Description: A modification of the Tergra model (Soer, 1977) is presented, which incorporates the scattering from arbitrarily inclined leaves canopy reflectance model (Verhoef and Bunnik, 1981) for the calculation of albedo and canopy resistance. The combined model, known as Tersail, is capable of simulating the relationship between the bidirectional reflectance and the thermal response of a canopy. The accuracy of the model is tested using data over wheat canopies in Phoenix, Arizona, showing that the model is a good simulator of canopy temperatures under a variety of conditions.
    Keywords: GEOPHYSICS
    Type: Remote Sensing of Environment (ISSN 0034-4257); 26; 287-300
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    Meteorite regolithic breccias (1988)
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    Publication Date: 2011-08-19
    Description: In addition to endogenic processes such as heating and aqueous activity, meteorite parent bodies were subjected also to exogenic processing brought about by the impact of the other solar-system objects. Such impacts can produce a variety of effects, ranging from shock metamorphism of individual mineral grains to production of breccias; i.e., rocks consisting of mixtures of disparate lithic units. The present paper reviews recent studies of such breccias, which have generated significant information about the accretional growth of parent bodies, as well as their evolution, composition, stratigraphy, and geological processing.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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    An intercomparison of results from ferrous sulphate and photolytic converter techniques for measurements of NO(x) made during the NASA GTE/CITE 1 aircraft program (1988)
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    Publication Date: 2011-08-19
    Description: Two techniques designed for measurements of NO(x (NO + NO2) were intercompared during aircraft flights made in the spring of 1984 in the middle free troposphere over the eastern Pacific Ocean and southwestern U.S. One NO chemiluminescence instrument was equipped with a ferrous sulphate converter, another with a photolytic converter. The ferrous sulphate-equipped instrument was apparently much less specific for NO2. It registered levels about three times larger than the photolytic converter and gave NO2/NO ratios that were much larger than photochemical calculations would indicate as reasonable. Additionally, the results imply that active NO(x) was only 10-20 percent of the total odd nitrogen in the middle free troposphere.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 15803-15
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    Extended sodium exosphere of the moon (1988)
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    Publication Date: 2011-08-19
    Description: Sodium emission has been observed up to 1200 km above the subsolar limb of the moon at third quarter. The intensity of the emission is far in excess of that predicted from the scale height and surface density derived previously from measurements of sodium emission at low altitudes above the lunar surface. This can be explained by assuming that there are both 'hot' and 'cold' components of the lunar sodium exosphere.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 15; 1515-151
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    Formation of the Antarctic ozone hole by the ClO dimer mechanism (1988)
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    Publication Date: 2011-08-19
    Description: New measurements of the low-altitude ClO profile, made during September 1987, are presented along with detailed observations of ozone depletion over McMurdo Station, Antarctica during the same period. The results show that both the rate and altitude range of ozone depletion can be quantitatively accounted for by a mechanism in which the ClO dimer is the important intermediary in the catalytic destruction of ozone. An alternative bromine mechanism appears capable of contributing only 5-15 percent to the ozone loss rate.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 336; 455-458
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    NO and NO2 in the troposphere - Technique and measurements in regions of a folded tropopause (1988)
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    Publication Date: 2011-08-19
    Description: Measurements of NO, NO2, O3, and CO were obtained for tropopause fold events encountered during two flights of the NASA global tropospheric experiment aircraft in 1984. The results suggest that NO(x) may not always be a good tracer of air of recent stratospheric origin. It is suggested that the stratospheric source of NO(x) acts to introduce NO(x) over a short period and through a large vertical region of the troposphere.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 15813-15
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    Chlorine-hydrocarbon photochemistry in the marine troposphere and lower stratosphere (1988)
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    Publication Date: 2011-08-19
    Description: The role of chlorine atoms in the oxidation of methane and nonmethane hydrocarbons (NMHCs) in the marine troposphere and lower stratosphere was investigated using a one-dimensional photochemical model that incorporated the chemistry of CH4, NMHCs, NO(x), O(x), and HO(x), as well as organic and inorganic halogens in the troposphere and lower stratosphere. The model predicted that chlorine atoms are present in the marine troposphere at the concentrations of about 1000/cu cm, mostly as a product of the reaction between OH and HCl released from sea spray. The results indicate that Cl atoms cause 20 to 40 percent of NMHC oxidation in the troposphere and 40 to 90 percent in the lower stratosphere. At 15 km, the NMHC-Cl reactions account for nearly 80 percent of the PAN produced. Where available, experimental data confirmed the model predictions.
    Keywords: GEOPHYSICS
    Type: Journal of Atmospheric Chemistry (ISSN 0167-7764); 7; 261-285
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    The effect of random precipitation times on the scavenging rate for tropospheric nitric acid (1988)
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    Publication Date: 2011-08-19
    Description: A model for the effective scavenging rate of a soluble species has been developed. The model takes into account the possibility of positive as well as negative correlations between departures from the mean of the scavenging rate and species concentration. The model is demonstrated for the case of late afternoon rainout of nitric acid occurring just prior to the nighttime cessation of its chemical production. The calculations give effective scavenging rates which are about a factor of 2 to 3 greater than those calculated using the models of Rodhe and Grandell (1972) and Giorgi and Chameides (1985).
    Keywords: GEOPHYSICS
    Type: Tellus, Series B - Chemical and Physical Meteorology (ISSN 0280-6509); 40B; 285-296
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    Changes in the earth's rate of rotation between A.D. 1672 and 1806 as deduced from solar eclipse timings (1988)
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    Publication Date: 2011-08-19
    Description: Solar eclipse timings measured between A.D. 1672 and 1806 are analyzed to study the variation of Delta T (= ET - UT) over this interval. These solar eclipse observations confirm the results of Brouwer (1952), Martin (1969), and Stephenson and Morrison (1969) which were obtained from the analysis of occultations in this period. It is believed that Goldstein's (1985) analysis inadequately represents the changes in Delta T.
    Keywords: GEOPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 200; 1-2,
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    Effect of the orbital debris environment on the high-energy Van Allen proton belt (1988)
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    Publication Date: 2011-08-19
    Description: The lifetimes of high-energy (greater than 55 MeV) protons in the Van Allen radiation belt are calculated, assuming that in time the protons will collide with and be absorbed by particulate orbiting material. The calculations are based on the NASA/DoD Civil Needs Database for orbital debris (Gaines, 1966) and moderate assumptions of future space traffic. It is found that the lifetimes of high-energy protons below 1500 km will decrease, leading to a noticeable redution in their fluxes.
    Keywords: GEOPHYSICS
    Type: Science (ISSN 0036-8075); 242; 1283-128
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    Io - Evidence for silicate volcanism in 1986 (1988)
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    Publication Date: 2011-08-19
    Description: Infrared observations of Io during the 1986 apparition of Jupiter indicate that a large eruptive event occurred on the leading side of Io on August 7, 1986, UT. Measurements made at 4.8, 8.7, and 20 micrometers suggest that the source of the event was about 15 kilometers in radius with a model temperature of about 900 K. These measurements indicate that high-temperature volcanic activity on the leading side of Io may be more frequent than previously thought. The inferred temperature is significantly above the boiling point of sulfur in a vacuum (715 K) and thus constitutes strong evidence for active silicate volcanism on the surface of Io.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 242; 1280-128
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    Mantle-derived fluids in diamond micro-inclusions (1988)
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    Publication Date: 2011-08-19
    Description: Microinclusions in diamonds from Zaire and Botswana differ in composition from the more common large inclusions of the peridotitic or eclogitic assemblages. These sub-micrometer inclusions resemble potassic magmas in their composition, but are enriched in H2O, CO2(3-), and K2O and depleted in MgO. This composition represents a volatile-rich fluid or melt from the upper mantle, which was trapped in the diamonds as they grew.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 335; 784-789
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    Stratospheric composition measurements of earth and Titan using high-resolution tunable diode laser spectroscopy (1988)
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    Publication Date: 2011-08-19
    Description: Field and laboratory measurements of species of atmospheric interest made as part of the JPL diode laser spectroscopy program are presented. Stratospheric measurements of NO2, NO, CO2, and H2O made in November 1985 using the BLISS instrument are reported, together with recent laboratory measurements of spectral line parameters of HNO3 and HO2NO2. In addition, a novel diode laser instrument concept for the in situ sensing of Titan's atmosphere is described for the Saturn Orbiter/Titan Probe (SOTP) Cassini Mission.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Quantitative Spectroscopy and Radiative Transfer (ISSN 0022-4073); 40; 239-248
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    Spectra of van der Waals complexes (dimers) with applications to planetary atmospheres (1988)
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    Publication Date: 2011-08-19
    Description: Spectral features observed in the atmosphere of Titan by the Voyager IR experiment have been attributed to weakly bound complexes of N2 and H2, dominant and minor constituents, respectively. The abundance of H2-N2 dimers there was computed. Current calculations include quantitative spectral line positions and intensities for N2-Ar and CO2-CO2 relating to Titan and Earth, and to Mars and Venus, respectively. This work suggests applications to spectra of planetary atmospheres obtained in spacecraft missions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Quantitative Spectroscopy and Radiative Transfer (ISSN 0022-4073); 40; 177-184
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    Zonally symmetric response to atmospheric tidal forcing in the dusty Martian atmosphere (1988)
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    Publication Date: 2011-08-19
    Description: The paper presents a steady state, zonally symmetric response of an atmospheric circulation to the combined effects of the very large zonal-mean diabatic heating and thermotidal forcing thought to exist in the dusty Martian atmosphere during one of its episodic global dust storms. The zonal-mean components of the tidal flux-convergences of momentum and heat are computed using an existing classical atmospheric tidal model constrained by the surface pressure observations at the two Viking Lander sites on Mars. A nearly inviscid two-dimensional model is used to compute the zonally symmetric response to the computed tidal flux-convergences and to the zonal-mean heating of the airborne dust. The results are compared with data from the Viking missions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 45; 2469-248
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    Lightning production of hydrocarbons and HCN on Titan - Laboratory measurements (1988)
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    Publication Date: 2011-08-19
    Description: Experimental measurements have been obtained for the chemical yields of hydrogen cyanide, acetylene, ethylene, ethane, and propane from simulated lightning discharges, in order to ascertain whether lightning in the troposphere of Titan may be contributing to the hydrocarbon inventory. A comparison of these results with those obtained on the basis of thermodynamic equilibrium considerations shows substantial discrepancies and implies that thermodynamic equilibrium theories are inadequate. The production of ethylene by lightning and its subsequent stratospheric diffusion nevertheless appears to be one reasonable mechanism.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 76; 125-134
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    Mars - Satellite and ring search from Viking (1988)
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    Publication Date: 2011-08-19
    Description: Viking Orbiter 1 imaging data were used in a search for possible satellites and rings of Mars in 1980, giving attention to a region within the Phobos orbit and + or - 350 km about the Martian equatorial plane. After picture processing, no images other than stars and Phobos itself were found to be a few brightnesses (or more) above their surrounding, as would be expected in the case of a point-spread, 'smeared' image of either satellites or rings. There is therefore no evidence of any such phenomenon in the 78 pictures studied.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 76; 160-162
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  • 87
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    Stratospheric NO2 over Antarctica as measured by the Solar Mesosphere Explorer during austral spring, 1986 (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: This paper presents the results of polar NO2 measurements carried out by the SME satellite during the fall and spring of 1985 and 1986 and compares the results with observations at the north pole and the results of model calculations. During the austral spring, a polar low was observed in stratospheric NO2 densities measured between 24 and 40 km, consistent with the predictions of standard photochemical theory. The geographic extent of the area of low NO2 densities was found to decrease as the hours of sunlight increased, in marked contrast to the behavior of the Antarctic ozone hole during the same period. A comparison of measurements with model calculations for NO2 imply that much of the odd nitrogen is converted to HNO3 during the polar night. Data also suggest no evidence that changes in high-altitude odd nitrogen are influencing the ozone below, or that the 'ozone hole' penetrates above 24 km to affect odd nitrogen there.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 12561-12
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  • 88
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    Measurement of nighttime stratospheric N2O5 from infrared emission spectra (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The mixing ratio profile of N2O5 has been inferred from high-resolution emission spectra obtained with a balloon-borne Fourier spectrometer. The observations were taken for the period from midnight to predawn on September 16, 1986 at 32 deg N latitude. The inferred volume mixing ratio from nighttime average spectra has a peak of about 1.8 x 10 to the -9th in the 32-35 altitude range. The inferred mixing ratio is generally less than the theoretical predictions from a one-dimensional model.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 15; 1177-118
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  • 89
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    The diamagnetic effect during AMPTE's tail releases - Initial results (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A series of four plasma injection experiments were performed by the AMPTE-IRM spacecraft in the nighttime magnetosphere between 12 and 18 earth radii geocentric distance during spring 1985. The most prominent effect of these tail releases is the creation of magnetic cavities. The lifetime of the cavities ranged from a few seconds to some minutes, depending mainly on the ion species and secondly on the ambient field strength. Due to the subsonic and sub-Alfvenic environment, the interaction between the plasma cloud and the ambient plasma flow played only a minor role in these cases (in contrast to the releases in the solar wind), and thus the diamagnetic effect could be studied extensively. The perturbation of the exterior field and fine structures in the current-carrying shell were observed. The thickness of the shell and the current distribution in this layer were deduced from the magnetic recordings each time IRM entered the cavity.
    Keywords: GEOPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 8; 1, 19
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  • 90
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    Magnetic ULF fluctuations in the compressional zone of AMPTE's artificial comets (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The two Ba releases in the solar wind, termed artificial comets (the first in interplanetary space, the second in the terrestrial magnetosheath), showed a number of common magnetic features. Both times a magnetic cavity was detected and a field pile-up observed with magnitudes several times the ambient field strength upstream of the cavity. The magnetic fluctuations in the compressed region are generally enhanced by a factor comparable to the amount of field pile-up. There is a peak in the spectra of both events around 0.1 Hz in the component which is perpendicular to the solar-wind velocity vector and almost field-aligned. This magnetosonic wave has been interpreted as the fundamental mode of resonance oscillations of the compression zone. For frequencies beyond 2 Hz the spectra decrease more steeply in the case of the second 'comet' than in the first. This is due to the interaction of the supersonic solar wind with the first comet. The spectra obtained during the first comet at the solar-wind/ion-cloud interface are identical to those observed during bow-shock crossings.
    Keywords: GEOPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 8; 1, 19; 23-26
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  • 91
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    Trends in atmospheric ozone - Conflicts between models and SBUV data (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Results obtained from simple models for the long-term change in ozone and its seasonal amplitude as a function of atmospheric pressure in the region from 3.0-0.1 mbar are compared with ozone measurements obtained with the Solar Backscatter Ultraviolet Instrument (SBUV). The SBUV data show secular trends in ozone which are negative and larger than the largest model trends by a factor of two or more. It is suggested that temperature-correlated variations in photochemistry should be included in the model.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 8431-843
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  • 92
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    Polar stratospheric clouds and the Antarctic ozone hole (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A theoretical model for the formation and growth of polar stratospheric clouds (PSCs) has been developed. Results for the calculated temperature dependence of optical backscattering are found to agree well with values obtained during two Arctic airborne-lidar experiments. Results for PSC formation in Antarctica show that at the 70-mbar level, about 80 percent of the HNO3 and about 30 percent of the H2O vapor available may be sequestered in relatively large PSC particles at a temperature near 189 K.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 8423-843
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  • 93
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    Smoke optical depths - Magnitude, variability, and wavelength dependence (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An airborne autotracking sun-photometer has been used to measure magnitudes, temporal/spatial variabilities, and the wavelength dependence of optical depths in the near-ultraviolet to near-infrared spectrum of smoke from two forest fires and one jet fuel fire and of background air. Jet fuel smoke optical depths were found to be generally less wavelength dependent than background aerosol optical depths. Forest fire smoke optical depths, however, showed a wide range of wavelength depedences, such as incidents of wavelength-independent extinction.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 8388-840
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  • 94
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    Pressure-induced absorption coefficients for radiative transfer calculations in Titan's atmosphere (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The semiempirical theory of Birnbaum and Cohen (1976) is used to calculate the FIR pressure-induced absorption (PIA) spectra of N2, CH4, N2 + Ar, N2 + CH4, and N2 + H2 under conditions like those in the Titan troposphere. The results are presented graphically and compared with published data from laboratory measurements of PIA in the same gases and mixtures (Dagg et al., 1986; Dore et al., 1986). Good agreement is obtained, with only a slight underestimation of PIA at 300-400/cm in the case of CH4. The absorption coefficients are presented in tables, and it is suggested that the present findings are of value for evaluating the effects of tropospheric clouds on the Titan FIR spectrum and studying the greenhouse effect near the Titan surface.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 75; 245-254
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  • 95
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    Methane rain on Titan (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The atmosphere of Titan is characterized by means of model computations based on Voyager IRIS IR spectra and published data from laboratory determinations of absorption coefficients and cloud refractive indices. The results are presented in tables and graphs, and it is pointed out that the presence of Ar is not required in the model. Particular attention is given to the role of CH4, which is found to form patchy clouds (with particle radii of 50 microns or greater and visible/IR optical depths of 2-5) at altitudes up to about 30 km. The mechanisms by which such rain-sized particles could form are discussed, and it is suggested that the observed 500-600/cm spectrum is affected much less by the CH4 clouds than by H2 or variations in the temperature of the high-altitude haze.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 75; 255-284
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  • 96
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    Modeling surface deformations at complex strike-slip plate boundaries (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Two new versions of the physical base-traction model of Li and Rice (1987) have been developed to study the loading processes and surface deformation near plate boundaries with geometric complexities, including a shallow creeping fault segment and two subparallel faults. Predictions of surface velocity and surface slip rate for the region between the San Andreas fault and the Pacific coast at the latitude of the Parkfield-Cholame segment using model parameters based on geologic, geodetic, and seismic considerations were found to be in good agreement with contemporary geodetic field data (not used in constrainning model parameters). Also, predicted surface velocity for the Salton Sea-Coachella Valley area were fit to recently derived contemporary geodetic data and very large baseline interferometry data, althoug here the model parameters are not well constrained.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 7943-795
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  • 97
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    Measurements of coseismic deformation in southern California - 1972-1982 (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: This paper compares records collected in the years 1972-1982 from two classes of instruments at Pinon Flat Observatory (PFO), southern California: the long-base-length (greater than 100 m) strain meters and tiltmeters described by Berger and Lovberg(1970) and Wyatt et al. (1982), respectively; and the short-base-length near-surface tiltmeters. It was found that the signals for static strain changes recorded by the long-base-length strain meters and tiltmeters are in good quantitative agreement with the deformation calculated for a dislocation in an elastic half-space. In contrast, colocated short-base-length tiltmeters produced spurious results, with signals much larger than the theoretical coseismic deformations computed using the U.S. Geological Survey/CalTech network; these signals correlated well with peak site acceleration.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 7923-794
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  • 98
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    Correlation of interannual length-of-day variation with El Nino/Southern Oscillation, 1972-1986 (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Correlation between interannual length-of-day (LOD) changes and an index representation of El Nino/Southern Oscillation (ENSO) for the period of 1972-1986 was examined in two ways: as the cross-correlation function in the time domain and as the complex coherence spectrum in the frequency domain. The ENSO representation was derived from barometric measurements from the Tahiti and Darwin, Australia, meteorological stations, as the difference of the sea-level pressure between the two locations. The cross correlation between this ENSO representation and LOD variation on the interannual time scale was found to have a maximum value of 0.68 and the LOD phase lag of 2 months, indicating that most of the interannual LOD variation is caused by ENSO, and that the transfer of ENSO's axial angular momentum to the solid earth lags behind the Tahiti-Darwin pressure variation by about 2 months. The corresponding coherence spectrum showed minimum correlation around biennial periods, indicating an influence of the stratospheric quasi-biennial oscillation on LOD variations.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 7709-771
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  • 99
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    Impact-driven supply of sodium and potassium to the atmosphere of Mercury (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The Mercury atmosphere is supplied with sodium atoms from both impacting meteoroids and the impacted regolith; the production of vaporized sodium due to such impact varies with the instantaneous distance of Mercury from the sun, in a way that differs from the distance-dependence of those source-and-sink processes driven by solar radiation. Such impact-driven vaporization will yield the Na/K ratio noted in the Mercury atmosphere only if both the meteoroids and the regolith of the planet are deficient in K relative to other solar system objects sampled, other than comets.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 75; 156-170
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  • 100
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    Enceladus - Implications of its unusual photometric properties (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Voyager 1 and 2 images are used to ascertain the photometric properties of Enceladus up to a 43-deg phase angle. The lack of correlation noted between spectrophotometric properties and terrain type indicates that optical characteristics result from a recently-deposited, ubiquitous surface layer that may have originated on the E-ring of Saturn. Enceladus' distinctive phase and photometric functions can be accounted for by the high degree of surface multiple scattering; observations to date indicate that the Enceladus regolith's textural characteristics are similar to those of other icy satellites of Saturn.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 75; 113-126
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