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  • Inorganic Chemistry  (639)
  • LUNAR AND PLANETARY EXPLORATION  (585)
  • FLUID MECHANICS AND HEAT TRANSFER  (498)
  • METEOROLOGY AND CLIMATOLOGY
  • 1985-1989  (2,052)
  • 1980-1984
  • 1960-1964
  • 1915-1919
  • 1988  (2,052)
Collection
Keywords
Publisher
Years
  • 1985-1989  (2,052)
  • 1980-1984
  • 1960-1964
  • 1915-1919
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
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    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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    A direct interaction approximation treatment of turbulence in a compressible fluid. I - Formalism (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The direct interaction approximation is used to treat turbulence in a compressible medium with constant mean gradients. The set of coupled nonlinear integrodifferential equations is derived that is satisfied by the transverse and longitudinal energy spectral functions, Q(T) and Q(L) and by the transverse and longitudinal response functions, G(T) and G(L). Finally, expressions for the average of the product of pairs of physically relevant fluctuating quantities (velocity, temperature, density) are derived in terms of Q(T) and Q(L).
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids (ISSN 0031-9171); 31; 1034-105
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  • 5
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    Surficial textures of the Galilean satellites (1988)
    In:  Other Sources
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    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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  • 6
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    A model of stationary gravity wave breakdown with convective adjustment (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A steady WKB model of gravity wave propagation including convective adjustment is used to investigate approximations used in various gravity-wave parameterization schemes. First, it is shown that estimates of the wave breaking height assuming a single horizontal wavenumber gravity wave can lead to errors if the topography is not sinusoidal. Second, the model results show that the assumption that wave growth ceases with the onset of convection or shear instability is an oversimplification. Since convection appears first over a very limited spatial region of the wave field, the wave is initially unaffected by turbulent mixing. However, when the convection zone spreads over a large portion of the wave field the amplitude is constrained. Estimates of the heat flux by breaking gravity waves are used to develop a simple parameterization of the vertical diffusion in terms of the Reynolds stress.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 45; 980-992
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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
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    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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    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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  • 9
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    A generalization of Petterssen's frontogenesis function and its relation to the forcing of vertical motion (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The classic Peterssen frontogenesis function, defined as the Lagrangian rate of change of the magnitude of the potential temperature gradient, is generalized to apply to the vector potential temperature gradient. The derivation of vector frontogenesis in natural coordinates is shown, and analytical examples of frontal evolution in nondivergent horizontal velocity fields are given which suggest that both the frontogenetic and rotational components of the vector frontogenesis function F may be comparable in developing frontal zones observed in nature. The relative importance of the magnitude and direction contributions to F is quantitatively investigated, and it is found that the Lagrangian rates of change of the magnitude and direction of the potential temperature gradient are comparable. The frontal circulation is found to be related to the magnitude component of the Q vector, whereas the background circulation is related to the direction component.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Monthly Weather Review (ISSN 0027-0644); 116; 762-780
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  • 10
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    Generalized energy and potential enstrophy conserving finite difference schemes for the shallow water equations (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The conditions under which finite difference schemes for the shallow water equations can conserve both total energy and potential enstrophy are considered. A method of deriving such schemes using operator formalism is developed. Several such schemes are derived for the A-, B- and C-grids. The derived schemes include second-order schemes and pseudo-fourth-order schemes. The simplest B-grid pseudo-fourth-order schemes are presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Monthly Weather Review (ISSN 0027-0644); 116; 650-662
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  • 11
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    Effects of using a posteriori methods for the conservation of integral invariants (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The nature and effect of using a posteriori adjustments to nonconservative finite-difference schemes to enforce integral invariants of the corresponding analytic system are examined. The method of a posteriori integral constraint restoration is analyzed for the case of linear advection, and the harmonic response associated with the a posteriori adjustments is examined in detail. The conservative properties of the shallow water system are reviewed, and the constraint restoration algorithm applied to the shallow water equations are described. A comparison is made between forecasts obtained using implicit and a posteriori methods for the conservation of mass, energy, and potential enstrophy in the complete nonlinear shallow-water system.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Monthly Weather Review (ISSN 0027-0644); 116; 525-545
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  • 12
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    Assessment of polar climate change using satellite technology (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Using results of selected studies, this paper highlights some of the problems that exist in the remote sensing of snow and ice, and demonstrates the importance of remote sensing for the study of snow and ice in determining the effect of temperature increase, due to the atmospheric CO2 increase, on the cryospheric features. Evidence obtained from NOAA, Nimbus, and other satellites, that may already indicate a global or at least a regional warming, includes an increase in permafrost temperature in northern Alaska and the retreat of many of the world's small glaciers in the last 100 years. It is emphasized that remote sensing is of major importance as the method of obtaining data for monitoring future changes in cryospheric features.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Reviews of Geophysics (ISSN 8755-1209); 26; 26-39
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  • 13
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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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  • 14
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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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  • 15
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    A proposed tropical rainfall measuring mission (TRMM) satellite (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The proposed Tropical Rainfall Measuring Mission (TRMM) satellite (presently in its third year of planning), is described. The TRMM satellite, planned for an operational duration of at least three years beginning in the mid-1990s, is intended to obtain high-quality measurements of tropical precipitation by means of information derived from a quantitative spaceborne radar, a multichannel passive microwave radiometer, and an AVHRR. The satellite's orbit will be low-altitude (320 km), for high resolution, and low-inclination (30 to 35 deg), for making it possible to visit each sampling area twice a day. Radar and passive microwave algorithms and rain-retrieval algorithms to be used in precipitation measurements are discussed together with cloud dynamical models designed to test these algorithms.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: American Meteorological Society, Bulletin (ISSN 0003-0007); 69; 278-295
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  • 16
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    A satellite infrared technique to estimate tropical convective and stratiform rainfall (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A new method of estimating both convective and stratiform precipitation from satellite infrared data is described. This technique defines convective cores and assigns rain rate and rain area to these features based on the infrared brightness temperature and the cloud model approach of Adler and Mack (1984). The method was tested for four south Florida cases during the second Florida Area Cumulus Experiment, and the results are presented and compared with three other satellite rain estimation schemes.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Applied Meteorology (ISSN 0733-3021); 27; 30-51
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  • 17
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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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  • 18
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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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  • 19
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    Renormalization-group theory for the eddy viscosity in subgrid modeling (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Renormalization-group theory is applied to incompressible three-dimensional Navier-Stokes turbulence so as to eliminate unresolvable small scales. The renormalized Navier-Stokes equation now includes a triple nonlinearity with the eddy viscosity exhibiting a mild cusp behavior, in qualitative agreement with the test-field model results of Kraichnan. For the cusp behavior to arise, not only is the triple nonlinearity necessary but the effects of pressure must be incorporated in the triple term. The renormalized eddy viscosity will not exhibit a cusp behavior if it is assumed that a spectral gap exists between the large and small scales.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physical Review A - General Physics, 3rd Series (ISSN 0556-2791); 37; 2590-259
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  • 20
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    Genesis of Atlantic Lows Experiment (GALE) - An overview (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The field phase of the Genesis of Atlantic Lows Experiment (GALE) was conducted from 15 January to 15 March 1986. The objectives of GALE were to study mesoscale and air-sea interaction processes in East Coast winter storms, with particular emphasis on their contributions to cyclogenesis. This project area, specail observing systems, and field operations are described. There were thirteen special observing periods during the field phase including eight cases of cyclogenesis. Meterological and oceanographic phenomena on which special observations were collected include: cyclogenesis, rainbands, cold fronts, coastal fronts, cold-air damming, jets streaks, tropopause folding, low-level jets, cold-air outbreaks, lightning and marine boundary layer interactions with Gulf Stream and mid-shelf oceanic fronts. Preliminary research findings and operational implications are presented. GALE data documents are listed. The GALE data set is open to all interested scientists.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: American Meteorological Society, Bulletin (ISSN 0003-0007); 69; 148-160
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  • 21
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    Diagnostic study of explosive cyclogenesis during FGGE (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Two rapidly developing extratropical maritime cyclones (one, developed during January 13-15, 1979, along an intense frontal zone south of Japan, the other, of January 26-27, 1979, in a polar mass over the North Atlantic) were investigated using the FGGE data and ECMWF level IIIb analyses to describe the structure and dynamics of these events. Although the cyclones evolved from a strong low-level baroclinic zone without initial large midtropospheric vorticity advection, thus resembling the Petterssen type A development, rapid deepening occurred in both cases when an approaching upper tropospheric jet with appreciable shear vorticity advection became favorably superposed over the surface low. During the development period, stability decreased in the low troposphere, aiding in the rapid development of an intense mass-circulation and low tropospheric vorticity production by the divergence term. The results suggest that upper-level forcing plays a greater role in the initiation of explosive oceanic development than is suggested by the Petterssen and Smebye (1971) description.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Monthly Weather Review (ISSN 0027-0644); 116; 431-451
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  • 22
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    Medium range lagged average forecasts (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: In this work, the application of the lagged average forecasting (LAF) technique to operational forecasts of the ECMWF is reported. The ECMWF data consist of two 100-day samples of 10-day forecasts of 500-mb geopotential height for winter 1980/81 and summer 1981. the LAF ensemble includes the latest operational forecast, and also forecast for the same verification time started one or more days earlier than the latest one. The focus is on the following two issues: (1) does ensemble averaging improve forecast skill and (2) is the dispersion of the ensemble useful in predicting forecast skill. The LAF technique was used to produce 3, 5, 7, 8, and 9 day forecasts of the 500-mb height field. The results show that the statistically filtered LAF is a marked improvment upon the operational forecast after 5 days. It is found that on a global scale, forecast skill is weakly correlated with the dispersion of the ensemble, as measured by the rms difference between the operational forecast and the statistically filtered LAF.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Monthly Weather Review (ISSN 0027-0644); 116; 402-416
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  • 23
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    Design of a nonsingular Level 2.5 second-order closure model for the prediction of atmospheric turbulence (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The suitability of applying the Mellor and Yamada (1974, 1982) Level 2.5 second-order turbulence closure model to general circulation models is investigated by examining not only the scheme's simulation of fully (or nearly fully) developed turbulence, but also its simulation of rapidly growing or strongly decaying turbulence. The behavior of the model is presented over its entire domain of definition, with special consideration given to the pathologies of the model. The model is then modified for the case of growing turbulence to rectify some of its physical shortcomings for that case, and to remove the pathologies that prohibit its use in a general circulation model. The performance of the modified Level 2.5 model is compared to the performance of various other modified versions through the numerical simulation for a growing convective PBL. The results show that the modified Level 2.5 model is a viable candidate for the prediction of turbulence and the simulation of the PBL in general circulation models.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 45; 113-132
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  • 24
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    The centring dynamics of a thin liquid shell in capillary oscillations (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The physical mechanism governing the centring of a hollow liquid shell in capillary oscillations, which has been observed in experiments, is investigated theoretically. First, the shell is assumed to be inviscid and to have a thickness that is much less than its spherical radius. A system of one-dimensional nonlinear equations of motion is derived using a thin-sheet model. From a numerical study the nonlinear effects of the wave are found to cause the core to oscillate slowly relative to the shell while the centre of mass of the whole system remains stationary. The effects of small viscosity are then considered in an approximation. Finally the strength of the centring mechanism is compared with that of the decentring effect due to buoyancy. The findings are consistent with the limited experimental information available.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics (ISSN 0022-1120); 188; 411-435
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  • 25
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    Developing fluid flow in a curved duct of square cross-section and its fully developed dual solutions (1988)
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    Publication Date: 2011-08-19
    Description: Developing fluid flow in a curved duct of square cross-section is studied numerically by a factored ADI finite-difference method on a staggered grid. A central-difference scheme with primitive variables is used inside the computational domain to reduce numerical diffusion. Two Reynolds numbers, 574 and 790, based upon a bulk velocity and hydraulic diameter are chosen for curvature ratios of 1/6.45 and 1/2.3, respectively. It is found that the secondary flow is far more complicated than expected, with the appearance of at least two pairs of vortices. Main-flow separation is also observed for the higher curvature ratio. Furthermore, it is observed that the flow develops into two quite different states downstream, depending upon the inlet conditions. Solutions of the fully developed Navier-Stokes equations is shown to be not unique beyond a certain critical Reynolds number. Developing flow seems to evolve into the fully developed state along a particular branch into which the fully developed solution bifurcates.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics (ISSN 0022-1120); 188; 337-361
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  • 26
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    Large impact basins and the mega-impact origin for the crustal dichotomy on Mars (1988)
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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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  • 27
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    Multiphase flow in porous media (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A development history and current status evaluation are presented for the theory of permeability and percolation. The microscale phenomena treated in this field have proven difficult to analyze due both to their tortuous geometry and the influence of capilarity. Capilary effects may be not only important but predominant, and are differentiated into those at the fluid-fluid interface, and those involving the existence of a contact line between the solid substrate and this interface. Percolation theory has been borrowed from physics and adapted to the two-phase engineering context.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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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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  • 29
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    The relative utility of persistence and medium-range dynamical forecasts of monthly mean 700 mb heights (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The proposal of Harnack et al. (1986) that monthly 700-mb height anomalies can be predicted using simulated medium-range numerical forecasts is tested with actual numerical forecasts produced under strict operational conditions. These conditions included nonavailability of long model forecast histories from which to develop estimates of drift, frequent model changes over the period of the experiment, a requirement that each monthly forecast be made four days before the beginning of the month, and the use of only data which are available on the day of the forecast. The overall results and month-by-month results confirm the hypothesis of the Harnack group.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Monthly Weather Review (ISSN 0027-0644); 116; 266-268
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  • 30
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    Condensation heat transfer in a microgravity environment (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Thermophysics and Heat Transfer (ISSN 0887-8722); 2; 82-84
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    Flow-induced morphological instabilities - The rotating disc (1988)
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    Publication Date: 2011-08-19
    Description: The morphological stability of a rotating and solidifying disk is investigated under the assumption that delta, the thickness of the viscous boundary layer, is much larger than delta(c), the thickness of the solute boundary layer. It is found that axisymmetric disturbances with wavelengths comparable to delta respond to nonparallel flow effects and have stability characteristics quite different from disturbances in a parallel flow. These long waves are unstable because of the nonparallel flow and would decay without it. This analysis thus identifies a new mechanism of morphological change induced by flow.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Crystal Growth (ISSN 0022-0248); 87; 4, Ma; 385-396
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  • 32
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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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  • 33
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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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  • 34
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    Voyager at Uranus (1988)
    In:  Other Sources
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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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  • 35
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    On the receptivity of free shear layers to two-dimensional external excitation (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: In this paper, the receptivity of a typical free shear layer to pulse-type and periodic excitation is studied. This is done by solving the initial-value problem completely and studing its long-time behavior. This leads to a wave packet for the pulse. By the superposition of many wave packets, a spatial instability mode when the flow is convectively unstable is generated. This establishes a general and simple relationship between the receptivities for pulse-type and sinusoidal excitations. It is found that a shear layer is very receptive to high-frequency disturbances that are generated near the centerline of the layer.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics (ISSN 0022-1120); 187; 155-177
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  • 36
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    Direct simulation of a turbulent boundary layer up to R sub theta = 1410 (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The turbulent boundary layer on a flat plate, with zero pressure gradient, is simulated numerically at four stations between R sub theta = 225 and R sub theta = 1410. The three-dimensional time-dependent Navier-Stokes equations are solved using a spectral method with up to about 10 to the 7th grid points. Periodic spanwise and streamwise conditions are applied, and a multiple-scale procedure is applied to approximate the slow streamwise growth of the boundary layer. The flow is studied, primarily, from a statistical point of view. The solutions are compared with experimental results. The scaling of the mean and turbulent quantities with Reynolds number is compared with accepted laws, and the significant deviations are documented. The turbulence at the highest Reynolds number is studied in detail. The spectra are compared with various theoretical models. Reynolds-stress budget data are provided for turbulence-model testing.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics (ISSN 0022-1120); 187; 61-98
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  • 37
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    A direct interaction approximation treatment of high Rayleigh number convective turbulence and comparison with experiment (1988)
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    Publication Date: 2011-08-19
    Description: A method is proposed for treating steady-state, thermally driven convection using the full direct interaction approximation to treat the nonlinear energy transfer and a prescribed instability function to model the eenrgy input. The instability function used is the growth rate of the mechanism generating the turbulence. This methodology can be easily generalized and applied to other driving mechanisms. The 1/3 power law form of the N vs. R relation for water is duplicated here and the coefficient is computed, using a two-point closure, to be less than about 0.08.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids (ISSN 0031-9171); 31; 256-262
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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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  • 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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    Thin cirrus clouds - Seasonal distribution over oceans deduced from Nimbus-4 IRIS (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Spectral differences in the extinction of the 10.8- and 12.6-micron bands of the IR window region, due to optically thin clouds, were found in the measurements made by both an airborne broadband IR radiometer and the IR interferometer spectrometer (IRIS) aboard the Nimbus-4 satellite; the extinction at 12.6 microns was significantly larger than that at 10.8 microns; both water and ice particles in the clouds can account for such spectral difference in extinction. Multiple scattering radiative transfer calculations of IRIS data revealed this spectral feature about 100 to 20 km away from the high-altitude cold clouds; it is assumed that this feature is related to the spreading of cirrus clouds. Based on this assumption, mean seasonal maps of the distribution of thin cirrus clouds over the oceans were deduced from the IRIS data. The maps show that such clouds are often present over the convectively active areas, such as ITCZ, SPCZ, and the Bay of Bengal during the summer monsoon.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Applied Meteorology (ISSN 0894-8763); 27; 379-399
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  • 41
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    Velocity spectra in the irrotational flow outside a turbulent shear layer (1988)
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    Publication Date: 2011-08-19
    Description: The relationship between the spectra of the three normal stresses near a turbulent shear layer is derived from the constraint of irrotationality. The relationship implies that the common practice of determining time scales of the turbulence from spectra in the near field is not valid. This implication is reinforced by a discussion of the scaling of irrotational spectra that follows from the formulation of Phillips (1975).
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids (ISSN 0031-9171); 31; 1807
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  • 42
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    Ejection mechanisms in the sublayer of a turbulent channel (1988)
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    Publication Date: 2011-08-19
    Description: The structure of the vorticity field in the viscous wall layer of a turbulent channel is studied by examining the results of a fully resolved direct numerical simulation. It is shown that this region is dominated by intense three-dimensional shear layers in which the dominant vorticity component is spanwise. The advection and reproduction processes of these structures are examined and shown to be consistent with the classical generation mechanism for two-dimensional Tollmien-Schlichting waves. This process is fundamentally different from the usually accepted mechanism involving hairpin vortices.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids (ISSN 0031-9171); 31; 1311-131
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  • 43
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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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    Charged particle depletion surrounding Saturn's F ring - Evidence for a moonlet belt? (1988)
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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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  • 45
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    Planetographic clustering of low-altitude impulsive electric signals in the night ionosphere of Venus (1988)
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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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    '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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  • 47
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    Evapotranspiration from nonuniform surfaces - A first approach for short-term numerical weather prediction (1988)
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    Publication Date: 2011-08-19
    Description: Observations of surface heterogeneity of soil moisture from scales of meters to hundreds of kilometers are discussed, and a relationship between grid element size and soil moisture variability is presented. An evapotranspiration model is presented which accounts for the variability of soil moisture, standing surface water, and vegetation internal and stomatal resistance to moisture flow from the soil. The mean values and standard deviations of these parameters are required as input to the model. Tests of this model against field observations are reported, and extensive sensitivity tests are presented which explore the importance of including subgrid-scale variability in an evapotranspiration model.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Monthly Weather Review (ISSN 0027-0644); 116; 600-621
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  • 48
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    On the accuracy of monthly mean wind speeds over the equatorial Pacific (1988)
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    Publication Date: 2011-08-19
    Description: In this paper, yearlong in situ wind measurements at a 3.8-m height, obtained at three sites along the Pacific equator (95, 110, and 152 deg W), were used to estimate the number of random observations required per month for monthly mean wind speeds accurate to 1.0 m/s and 0.5 m/s. Wind measurements were made with a vector-averaging wind recorder mounted on a surface-following toroid float, which measured speed continuously, and direction nearly continuously. For equatorial Pacific winds in the 95 to 152 deg W region, the typical numbers of random wind observations required per month were found to be about nine for a 1.0 m/s accuracy, and 35 for a 0.5 m/s accuracy. The corresponding number of ship winds would likely be greater. The number of random observations required increased westward and was highly correlated with monthly mean standard deviations.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Atmospheric and Oceanic Technology (ISSN 0739-0572); 5; 362-367
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  • 49
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    First-guess dependence of a physically based set of temperature-humidity retrievals from HIRS2/MSU data (1988)
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    Publication Date: 2011-08-19
    Description: The first-guess dependence of temperature and humidity fields retrieved from HIRS2/MSU data using the GLA (Goddard Laboratory for Atmospheres) physically based retrieval scheme is examined. Retrievals were performed over the ALPEX region for two successive synoptic periods, 1200 UTC March 4 and 00000 UTC March 5, 1982, using three different initial guesses for each period. Results show rather low first-guess dependence for the thickness fields and larger first-guess dependence for the precipitable water fields, especially close to the surface. The humidity retrieval algorithm used is described. The processing system has the property of maintaining the accuracy of a good guess and improving a poor one for both thickness and precipitable water at all levels.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Atmospheric and Oceanic Technology (ISSN 0739-0572); 5; 70-83
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    A vertically integrated snow/ice model over land/sea for climate models. I - Development. II - Impact on orbital change experiments (1988)
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    Publication Date: 2011-08-19
    Description: A vertically integrated formulation (VIF) model for sea ice/snow and land snow is discussed which can simulate the nonlinear effects of heat storage and transfer through the layers of snow and ice. The VIF demonstates the accuracy of the multilayer formulation, while benefitting from the computational flexibility of linear formulations. In the second part, the model is implemented in a seasonal dynamic zonally averaged climate model. It is found that, in response to a change between extreme high and low summer insolation orbits, the winter orbital change dominates over the opposite summer change for sea ice. For snow over land the shorter but more pronounced summer orbital change is shown to dominate.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 3663-367
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    Vacillations in a coupled ocean-atmosphere model (1988)
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    Publication Date: 2011-08-19
    Description: Results are presented from a 35-year integration of a coupled ocean-atmosphere model. Both ocean and atmosphere are two-level, nonlinear primitive equation models. The global atmospheric model is forced by a steady, zonally symmetric Newtonian heating. The ocean model is solved in a rectangular tropical basin. Heat fluxes between ocean and atmosphere are linear in air-sea temperature differences, and the interfacial stress is proportional to lower-level atmospheric winds. The coupled models produce ENSO-like variability on time scales of 3 to 5 years. Since there is no external time-dependent forcing, these are self-sustained vacillations of the nonlinear system. It is argued that the energetics of the vacillations is that of unstable coupled modes and that the time scale is crucially dependent on the effects of ocean waves propagating in a closed basin.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 45; 549-566
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    The GISS global climate-middle atmosphere model. I - Model structure and climatology (1988)
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    Publication Date: 2011-08-19
    Description: A coupled global climate/middle atmosphere model (GCMAM) is developed by extending the Hansen et al. (1983) GISS global climate model to include the middle atmosphere up to 85 km. The model includes numerical solutions of the primitive equations, calculations of the radiative and surface fluxes, and a complete hydrologic cycle with convective and cloud-cover parameterizations. In addition, a parameterized gravity wave drag cycle is incorporated, in which gravity-wave momentum fluxes due to flow over topography, wind shear, and convection are calculated at each grid box, using theoretical relationships between the grid-scale variables and expected source strengths. The results of the GCMAM demonstrate that the model produces a reasonable simulation of the stratosphere. It is shown that the improvements over the previous version were achieved largely through the incorporation of the parameterized gravity wave drag.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 45; 329-370
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    A finite element computation of turbulent boundary layer flows with an algebraic stress turbulence model (1988)
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    Publication Date: 2011-08-19
    Description: An algebraic stress turbulence model and a computational procedure for turbulent boundary layer flows which is based on the semidiscrete Galerkin FEM are discussed. In the algebraic stress turbulence model, the eddy viscosity expression is obtained from the Reynolds stress turbulence model, and the turbulent kinetic energy dissipation rate equation is improved by including a production range time scale. Good agreement with experimental data is found for the examples of a fully developed channel flow, a fully developed pipe flow, a flat plate boundary layer flow, a plane jet exhausting into a moving stream, a circular jet exhausting into a moving stream, and a wall jet flow.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Computer Methods in Applied Mechanics and Engineering (ISSN 0045-7825); 66; 45-63
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    The GISS global climate-middle atmosphere model. II - Model variability due to interactions between planetary waves, the mean circulation and gravity wave drag (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The variability which arises in the GISS Global Climate-Middle Atmosphere Model on two time scales is reviewed: interannual standard deviations, derived from the five-year control run, and intraseasonal variability as exemplified by statospheric warnings. The model's extratropical variability for both mean fields and eddy statistics appears reasonable when compared with observations, while the tropical wind variability near the stratopause may be excessive possibly, due to inertial oscillations. Both wave 1 and wave 2 warmings develop, with connections to tropospheric forcing. Variability on both time scales results from a complex set of interactions among planetary waves, the mean circulation, and gravity wave drag. Specific examples of these interactions are presented, which imply that variability in gravity wave forcing and drag may be an important component of the variability of the middle atmosphere.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 45; 371-386
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    Trace gas exchanges and convective transports over the Amazonian rain forest (1988)
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    Publication Date: 2011-08-19
    Description: The NASA Amazon Boundary Layer Experiment (ABLE 2A) based in Manaus, Brazil, in July and August 1985, is used to examine meteorological processes responsible for the vertical and horizontal transport of biogenic and anthropogenic trace gases generated over the Amazon basin. Direct sampling of the surrounding environment of deep convective clouds shows marked changes in the vertical distribution of the lower and midtroposphere concentration of O3 and such surface-derived species as CO, CO2, and NO. Thermodynamic observations, together with two-dimensional cloud model simulations, confirm vertical transports within the convection and provide a basis for an estimation of the magnitude and efficiency of cloud upward and downward exchanges. A distinction is drawn between local changes due to convective updrafts and downdrafts and convective overturning as a net result of the storm processes. Marked variability is seen in trace gas concentrations along horizontal flight paths in the vicinity of the convection. Interpretation of simultaneously measured thermodynamic quantities and trace gas concentrations provide the information to infer the presence and direction of atmospheric transports and/or the presence of anthropogenic influences.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1528-155
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    Airborne lidar observations of Arctic polar stratospheric clouds - Indications of two distinct growth stages (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Airborne lidar observations of Arctic polar stratospheric clouds (PSCs) during January 1984 and January 1986 show contrast suggestive of two distinct PSC growth stages delineated by the frost-point temperature. Results obtained at temperatures 2-6 K above the frost point indicate a stage of significant, but limited, particle growth such as proposed in recent models of PSC formation by co-deposition of HNO3 and H2O vapors. Results obtained at a temperature near the frost point indicate the formation of somewhat larger crystalline particles.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Geophysical Research Letters (ISSN 0094-8276); 15; 21-23
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    Free-streamline analysis of deformation and dislodging by wind force of drops on a surface (1988)
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    Publication Date: 2011-08-19
    Description: Free-streamline theory is used to analyze the deformation and dislodging by wind pressure of drops of liquid adhered by surface tension to a solid surface. The critical Weber number for droplets to be dislodged is determined as a function of advancing and receding contact angle. Graphical results for drop shape are in good agreement with observation.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids (ISSN 0031-9171); 31; 43-48
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    Are there carbonate deposits in the Valles Marineris, Mars? (1988)
    In:  Other Sources
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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 estimation of precipitation intensity in the presence of surface backscatter and the converse using a spaceborne radar (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The 'rain-modified' surface backscattering coefficient and the rain intensity can be estimated simultaneously by analyzing the return echo waveforms obtained by a nonnadir pointing spaceborne radar. Preliminary simulation results, using system parameters for the TRMM rain mapping radar, indicate that path-averaged rain attenuation coefficient can be estimated to 20 percent by such technique.
    Keywords: METEOROLOGY AND CLIMATOLOGY
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    Could modern forecasting techniques have predicted the blizzard of 1888? (1988)
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    Publication Date: 2011-08-19
    Description: Surface meteorological data for March 1888, which were collected at 170 stations across the U.S. three times a day, are combined with ship reports to construct a surface weather analysis for the blizzard of 1888. Surface weather charts are constructed to determine the ability of current forecasting techniques to predict the blizzard. The evolution of the storm is described in detail and current methods for treating a storm of similar intensity are discussed.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Earth in Space (ISSN 1040-3124); 1; 5-9
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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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    On air motion trajectories in cold fronts (1988)
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    Publication Date: 2011-08-19
    Description: This paper examines air parcel trajectories in the two-dimensional model for a cold front by Reeder and Smith (1987). These are found to be in close agreement with trajectories deduced from analyses of summertime 'cool changes' in southeastern Australia, adding further support to the applicability of the numerical model to this kind of cold front. The favorable comparison points also to the dynamical consistency of the conceptual model for the cool change, which has evolved from the analysis of data from observational experiments.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 45; 4005-400
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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.
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    A comparison of a GCM simulation of the seasonal cycle of the atmosphere with observation. I - Mean fields and the annual harmonic. II - Stationary waves and transient fluctuations (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The seasonal cycle of a GCM is analyzed in terms of the behavior of the monthly and seasonal mean fields and the structure of the annual harmonic. The GCM is found to be successful in simulating the Northern Hemisphere sea-level pressure and 200-mb heights over eastern continents and oceans and in the entire Southern Hemisphere. Problems in the simulation include an anomalously deep Aleutian low and low values of the height over Europe in winter. The GCM fails to show the observed amplitude of the annual harmonic in 200-mb temperature over Antarctica. In the second section, the seasonal dependence of the stationary and transient eddies of the GCM are presented for a two-year annual cycle. The accuracy of the wave and eddy simulations is analyzed.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Atmosphere - Ocean (ISSN 0705-5900); 26; 541-607
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    A mesoscale gravity wave event observed during CCOPE. III - Wave environment and probable source mechanisms (1988)
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    Publication Date: 2011-08-19
    Description: The multiscale environment of gravity wave events and the probable mechanisms of their origin are examined on the basis of observations taken during the Cooperative Convective Precipitation Experiment in extreme eastern Montana, during the period from 1200 UTC July 11, 1981, to 0500 UTC July 12. During this time, two distinct gravity wave episodes were diagnosed. The results of the analysis of the evolving structures in the subsynoptic-scale and mesoscale environments indicate that the observed mesoscale gravity waves were generated by geostrophic adjustment processes, with additional energy supplied through interaction with the critical level; their coherence was maintained through a ducting mechanism.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Monthly Weather Review (ISSN 0027-0644); 116; 2570-259
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    Sampling error study for rainfall estimate by satellite using a stochastic model (1988)
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    Publication Date: 2011-08-19
    Description: In a parameter study of satellite orbits, sampling errors of area-time averaged rain rate due to temporal sampling by satellites were estimated. The sampling characteristics were studied by accounting for the varying visiting intervals and varying fractions of averaging area on each visit as a function of the latitude of the grid box for a range of satellite orbital parameters. The sampling errors were estimated by a simple model based on the first-order Markov process of the time series of area averaged rain rates. For a satellite of nominal Tropical Rainfall Measuring Mission (Thiele, 1987) carrying an ideal scanning microwave radiometer for precipitation measurements, it is found that sampling error would be about 8 to 12 pct of estimated monthly mean rates over a grid box of 5 X 5 degrees. It is suggested that an observation system based on a low inclination satellite combined with a sunsynchronous satellite simultaneously might be the best candidate for making precipitation measurements from space.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Applied Meteorology (ISSN 0894-8763); 27; 1218-123
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    Considerations on the moving contact-line singularity, with application to frictional drag on a slender drop (1988)
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    Publication Date: 2011-08-19
    Description: It has previously been shown that the no-slip boundary conditions leads to a singularity at a moving contact line and that this presumes some form of slip. Present considerations on the energetics of slip due to shear stress lead to a yield stress boundary condition. A model for the distortion of the liquid state near solid boundaries gives a physical basis for this boundary condition. The yield stress condition is illustrated by an analysis of a slender drop rolling down an incline. That analysis provides a formula for the frictional drag resisting the drop movement. With the present boundary condition, the length of the slip region becomes a property of the fluid flow.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics (ISSN 0022-1120); 197; 157-169
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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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    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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    A GCM simulation study of the influence of Saharan evapotranspiration and surface-albedo anomalies on July circulation and rainfall (1988)
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    Publication Date: 2011-08-19
    Description: The influence of surface albedo and evapotranspiration anomalies that could result from the hypothetical semiarid vegetation over North Africa on its July circulation and rainfall is examined using the Goddard Laboratory for Atmospheres GCM. It is shown that increased soil moisture and its dependent evapotranspiration produces a cooler and moister PBL over North Africa that is able to support enhanced moist convection and rainfall in Sahel and southern Sahara. It is found that lower surface albedo yields even higher moist static energy in the PBL and enhances the local moist convection and rainfall. Modifying the rain-evaporation parameterization in the model produces changes in the hydrological cycle and rainfall anomalies in distant regions. The effects of different falling rain parameterizations are discussed.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Monthly Weather Review (ISSN 0027-0644); 116; 2388-240
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    The roles of dry convection, cloud-radiation feedback processes and the influence of recent improvements in the parameterization of convection in the GLA GCM (1988)
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    Publication Date: 2011-08-19
    Description: The Goddard Laboratory for Atmospheres GCM is used to study the sensitivity of the simulated July circulation to modifications in the parameterization of dry and moist convection, evaporation from falling raindrops, and cloud-radiation interaction. It is shown that the Arakawa-Schubert (1974) cumulus parameterization and a more realistic dry convective mixing calculation yielded a better intertropical convergence zone over North Africa than the previous convection scheme. It is found that the physical mechanism for the improvement was the upward mixing of PBL moisture by vigorous dry convective mixing. A modified rain-evaporation parameterization which accounts for raindrop size distribution, the atmospheric relative humidity, and a typical spatial rainfall intensity distribution for convective rain was developed and implemented. This scheme led to major improvements in the monthly mean vertical profiles of relative humidity and temperature, convective and large-scale cloudiness, rainfall distributions, and mean relative humidity in the PBL.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Monthly Weather Review (ISSN 0027-0644); 116; 2366-238
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    A model-based diagnostic study of the rapid development phase of the Presidents' Day cyclone (1988)
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    Publication Date: 2011-08-19
    Description: A model simulation of the rapid development phaser of the Presidents' Day cyclone on February 19, 1979, is studied. Model trajectories and Eulerian analyses show that, during this phase, three airstreams converge into the cyclogenetic region. The evolution of the PJ-trough system and its associated tropopause fold is described, including the simulated surface low and the vertical profile of mass divergence which contributes to the decreasing sea-level pressure. The various terms of the vorticity equation are evaluated to identify the processes contributing to the increase in absolute vorticity. The nature and origin of airstreams entering the low-level circulation associated with rapid cyclogenesis are examined from a Lagrangian perspective.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Monthly Weather Review (ISSN 0027-0644); 116; 2337-236
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    Satellite-observed characteristics of midwest severe thunderstorm anvils (1988)
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    Publication Date: 2011-08-19
    Description: The cloud top and anvil structure of severe thunderstorms observed by the GOES satellite are analyzed for five SESAME cases in 1979 and four non-SESAME cases in 1980-1982. The data is compared with previous models and hypotheses, paying particular attention to the V feature and thermal couplets in the IR observations. The characteristics of the cases are examined and related to the upper-level temperature and wind conditions. It is found that the warm points downwind of the cloud top are due to subsidence. The anaylsis suggests the presence of subsidence due to mountainlike waves. A model in which the close-in warm point is produced by both internal cloud air motions and stratospheric flow around and over the cloud top. It is suggested that the distant warm point is due to either a wave perturbation from air flowing over the cloud top, or air flowing horizonatlly around the elevated portion of the cloud top and anvil.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Monthly Weather Review (ISSN 0027-0644); 116; 2200-222
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    One-level modeling for diagnosing surface winds over complex terrain. II - Applicability to short-range forecasting (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The Alpert and Getenio (1988) modification of the Mass and Dempsey (1985) one-level sigma-surface model was used to study four synoptic events that included two winter cases (a Cyprus low and a Siberian high) and two summer cases. Results of statistical verification showed that the model is not only capable of diagnosing many details of surface mesoscale flow, but might also be useful for various applications which require operative short-range prediction of the diurnal changes of high-resolution surface flow over complex terrain, for example, in locating wildland fires, determining the dispersion of air pollutants, and predicting changes in wind energy or of surface wind for low-level air flights.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Monthly Weather Review (ISSN 0027-0644); 116; 2047-206
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    On the movement and low-level structure of cold fronts (1988)
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    Publication Date: 2011-08-19
    Description: Factors that are pertinent to the cold-front motion were examined using the results from previous studies of the low-level structure of cold fronts. Observational studies indicate the existence of two different types of behavior for a cold front. These types of behavior were related to the results of recent theoretical studies, and the mechanism responsible for front propagation was elucidated. It is shown that a necessary requirement for propagation is the existence of an alongfront temperature gradient.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Monthly Weather Review (ISSN 0027-0644); 116; 1927-194
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    Lower-upper Symmetric-Gauss-Seidel method for the Euler and Navier-Stokes equations (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 26; 1025
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    Sensitivity of a global climate model to the specification of convective updraft and downdraft mass fluxes (1988)
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    Publication Date: 2011-08-19
    Description: The response of the GISS global climate model to different parameterizations of moist convective mass flux is studied. A control run with arbitrarily specified updraft mass flux is compared to experiments predicting cumulus mass fulx on the basis of low-level convergence, convergence plus surface evaporation, or convergence and evaporation modified by varying boundary layer height. Also, an experiment that includes a simple parameterization of saturated convective-scale downdrafts is discussed. It is found that the model correctly simulates the correlation between deep convection strength and tropical sea surface temperature in each experiment with the parameterization of cumulus mass flux having little effect. The implications of the experiments for cloud effects on climate sensitivity are examined.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 45; 2641-266
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    Numerical study of the interactions between droplets at intermediate Reynolds numbers (1988)
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Propulsion and Power (ISSN 0748-4658); 4; 481-489
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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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    Unsteady solution of incompressible Navier-Stokes equations (1988)
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    Publication Date: 2011-08-19
    Description: The numerical scheme used by the present time-accurate FEM numerical method for incompressible Navier-Stokes equations, using primitive variables as the unknowns, is a Crank-Nicholson implicit treatment of all equation terms with central differencing for space derivatives. The introduction of a continuous auxilliary system in pseudo-time, with artificial compressibility, yields the incompressible solution at the advanced time level; time-accurate solutions are thereby obtained for two-dimensional fluid flows in a square cavity, in the cases of both an impulsively starting lid and an oscillating lid.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Computational Physics (ISSN 0021-9991); 79; 113-134
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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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  • 86
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    Lightning production of hydrocarbons and HCN on Titan - Laboratory measurements (1988)
    In:  Other Sources
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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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  • 87
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    Measurements of the free-stream fluctuations above a turbulent boundary layer (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The paper describes an investigation of the velocity fluctuations in the free stream above an incompressible turbulent boundary layer developing at constant pressure. Measurements were performed in a wind tunnel with an rms level of axial velocity fluctuations of about 0.2 percent. The possibility of assessing the contributions to the rms level of the velocity fluctuations without using the high-pass filtering technique is demonstrated.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids (ISSN 0031-9171); 31; 2834-284
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  • 88
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    Mars - Satellite and ring search from Viking (1988)
    In:  Other Sources
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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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  • 89
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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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  • 90
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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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  • 91
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    Model consistency in large eddy simulation of turbulent channel flows (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Combinations of filters and subgrid scale stress models for large eddy simulation of the Navier-Stokes equations are examined by a priori tests and numerical simulations. The structure of the subgrid scales is found to depend strongly on the type of filter used, and consistency between model and filter is essential to ensure accurate results. The implementation of consistent combinations of filter and model gives more accurate turbulence statistics than those obtained in previous investigations in which the models were chosen independently from the filter. Results and limitations of the a priori test are discussed. The effect of grid refinement is also examined.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids (ISSN 0031-9171); 31; 1884-189
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  • 92
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    Structure of rough-wall turbulent boundary layers (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Recent experiments have shown that, in rough-wall turbulent boundary layers, drag varies systematically with the spanwise aspect ratio lambda(z) (span/height) of roughness elements. In this paper, the effect of lambda(z) on turbulence structure has been examined. Based on lambda(z), the roughness in a transversely grooved surface with lambda(z) much greater than 1 is the opposite extreme of model plant canopies with lambda(z) much less than 1, studied in wind tunnels, whereas sandgrain is an intermediate type. Second-, third-, and fourth-order turbulence moments have been measured in turbulent boundary layers over transversely grooved and smooth surfaces and compared with available turbulence structure measurements over other types of surfaces. The near-wall turbulence structure is found to vary with lambda(z). The instantaneous motions involved in the flux of shear stress near the wall in smooth and transversely grooved surfaces are opposite in sign to those in three-dimensional roughness. The former is explained in terms of hairpin vortices alone, while the latter group is modeled to have an additional vortex (the so-called necklace vortex which straddles a three-dimensional roughness element near its base).
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids (ISSN 0031-9171); 31; 1877-188
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  • 93
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    Stability of swirling gas flows (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The stability of inviscid swirling gas flows to small nonaxisymmetric perturbations is considered. For small Brunt-Vaisala frequencies, the problem reduces to the classical Sturm-Liouville form and the oscillation theorem can be applied. The resulting necessary and sufficient stability condition is compared to various criteria in the literature and a limited numerical study of isothermal rigidly rotating Poiseuille flow. For given azimuthal and axial wavenumbers, it is found numerically that the higher inertial modes become unstable for successively lower Rossby numbers and that this sequence of critical values approaches the theoretical value from above.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids (ISSN 0031-9171); 31; 1872-187
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  • 94
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    Weak solutions of the three-dimensional vorticity equation with vortex singularities (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The extension of the concept of vortex singularities, developed by Saffman and Meiron (1986) for the case of two-dimensional point vortices in an incompressible vortical flow, to the three-dimensional case of vortex sticks (vortons) is investigated analytically. The derivation of the governing equations is explained, and it is demonstrated that the formulation obtained conserves total vorticity and is a weak solution of the vorticity equation, making it an appropriate means for representing three-dimensional vortical flows with limited numbers of vortex singularities.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids (ISSN 0031-9171); 31; 1838
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  • 95
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    The Nimbus-7 Global Cloud Climatology (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The Nimbus-7 Global Cloud Climatology (N7GCC) has been produced from measurements made between April 1979 and March 1985 using the Temperature Humidity IR Radiometer and the Total Ozone Mapping Spectrometer on the Nimbus-7 satellite. The N7GCC gives, near local noon and midnight, the fractional area covered by high-level, middle-level, and low-altitude clouds, and the total fractional area covered by all clouds. Statistics for cirrus, deep convective, and warm low-altitude clouds and the cloud and clear-sky radiances with correlative surface temperatures are also included. The N7GCC is compared with other cloud data sets, including the International Satellite Cloud Climatology Project.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: American Meteorological Society, Bulletin (ISSN 0003-0007); 69; 743-752
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  • 96
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    Heating rates in tropical anvils (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The interaction of infrared and solar radiation with tropical cirrus anvils is addressed. Optical properties of the anvils are inferred from satellite observations and from high-altitude aircraft measurements. An infrared multiple-scattering model is used to compute heating rates in tropical anvils. Layer-average heating rates in 2 km thick anvils were found to be on the order of 20 to 30 K/day. The difference between heating rates at cloud bottom and cloud top ranges from 30 to 200 K/day, leading to convective instability in the anvil. The calculations are most sensitive to the assumed ice water content, but also are affected by the vertical distribution of ice water content and by the anvil thickness. Solar heating in anvils is shown to be less important than infrared heating but not negligible. The dynamical implications of the computed heating rates are also explored and it is concluded that the heating may have important consequences for upward mass transport in the tropics. The potential impact of tropical cirrus on the tropical energy balance and cloud forcing are discussed.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 45; 1606-162
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  • 97
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    Rain simulation studies for high-intensity acoustic nose cavities (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Unarmed plastic projectiles can be equipped with small axisymmetric cavities for the generation of intense tones that are useful in training maneuvers. Attention is presently given to the simulation of rainfall in an airstream and the effect of rain droplet impingement on the nose of projectiles, and especially to any penetration or accumulation of water at the base of the cavity that might increase the fundamental cavity frequency and/or reduce the intensity of sound production during rain conditions.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 281-283
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  • 98
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    Comparison of high-altitude remote aircraft measurements with the radar structure of an Oklahoma thunderstorm - Implications for precipitation estimation from space (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The present NASA ER-2 aircraft observations of an isolated group of thunderstorms over Oklahoma, encompassing passive radiometry in the visible, IR, and microwave portions of the spectrum obtained above the storm top, is compared with coincident data from two Doppler radars as well as aircraft-gathered in situ cloud top particle data. Reflectivity cores are found to be nearly colocated with cold anomalies in the microwave brightness temperature field. Theoretical considerations suggesting that microwave frequencies are sensitive to the deeper layer of large ice particles in the storm's convective region are supported.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Monthly Weather Review (ISSN 0027-0644); 116; 1157-117
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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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