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  • AERODYNAMICS  (626)
  • METEOROLOGY AND CLIMATOLOGY  (623)
  • Biochemistry and Biotechnology  (603)
  • 550 - Earth sciences
  • Deutschland
  • 1990-1994  (1,912)
  • 1980-1984
  • 1990  (1,912)
Collection
Keywords
Publisher
Language
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  • 1990-1994  (1,912)
  • 1980-1984
Year
  • 1
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    Evolution of tropical circulation anomalies associated with 30-60 day oscillation of globally averaged angular momentum during northern summer (1990)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Lag correlation statistics was used to study intraseasonal variations of upper and lower-level zonal winds, outgoing longwave radiation, and globally averaged angular momentum (GAM) for northern summers of 1977-1984. The temporal and spatial distribution of surface wind stress in the tropics and its relationship with zonal wind anomalies were studied to assess the impact of surface frictional drag on the atmospheric angular momentum. The 30-60 day GAM fluctuation is shown to be accompanied by zonal propagation of convection and 850 mb zonal wind anomalies in the tropical belt. The climatological zonal wind in the tropics affects the magnitude of wind stress anomalies. It is suggested that momentum exchange between the lower and upper troposphere may occur in regions of active convection via vertical momentum transport. The tropical central Pacific is considered to play a key role in linking the atmosphere and the earth through angular momentum exchange on intraseasonal time scales.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Meteorological Society of Japan, Journal (ISSN 0026-1165); 68; 237-249
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  • 2
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    Tropical Rainfall Measuring Mission (TRMM) project. III - Japan-U.S. collaborative rain observation experiment using an airborne rain radar (1990)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: A collaborative rain-observation experiment using an airborne rain radar was conducted between Communications Research Laboratory (CRL) and Goddard Space Flight Center (GSFC)/NASA. CRL provided an airborne rain-radar/radiometer system and GSFC/NASA provided a NASA P3-A aircraft. Airborne or spaceborne rain-radar echoes have large sea or land-surface echoes. These surface echoes yield rain-estimation algorithms using rain attenuation. The experiment demonstrated the potential of the rain-estimation techniques using rain attenuation.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Communications Research Laboratory, Review (ISSN 0914-9279); 36; 11, J; 35-44
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  • 3
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    A comparison of optimization-based approaches for solving the aerodynamic design problem (1990)
    In:  CASI
    Details
    Publication Date: 2004-12-04
    Description: Three optimization-based methods for solving aerodynamic design problems are compared. The Euler equations for one-dimensional duct flow was used as a model problem, and the three methods are compared for efficiency, robustness, and implementation difficulty. The smoothness of the design problem with respect to different shock-capturing finite difference schemes, and in the presence of grid refinement, is investigated.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center, The Third Air Force(NASA Symposium on Recent Advances in Multidisciplinary Analysis and Optimization; p 77-88
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  • 4
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    Tropical Rainfall Measuring Mission (TRMM) project. V - Scientific background and goals of TRMM (1990)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The scientific goals of TRMM are described. TRMM provides quantitative measurements of tropical rain which can improve the understanding of the global climate. TRMM can also help to improve techniques for measuring rainfall from space.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Communications Research Laboratory, Review (ISSN 0914-9279); 36; 11, J; 57-70
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  • 5
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    ENSAERO - A multidisciplinary program for fluid/structural interaction studies of aerospace vehicles (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A computational procedure is developed that uses a moving zonal grid concept to model complex flexible aerospace vehicles. The Euler/Navier-Stokes equations are used to model the flow, and computations are made using efficient methods based on both central and upwind schemes. The structure is represented by a finite element method which can model general aerospace vehicles. Provisions are made to accommodate other disciplines such as controls and thermal loads. The code is capable of computing unsteady flows on flexible wings with vortical flows. Adaptation of this procedure for parallel processing and validation for complete aerospace configurations is in progress.
    Keywords: AERODYNAMICS
    Type: Computing Systems in Engineering (ISSN 0956-0521); 1; 2-4,
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  • 6
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    Aerothermodynamics of sprint-type manned Mars missions (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 27; 589-596
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  • 7
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    Remote sensing of surface turbulence heat flux (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The determination of latent heat-flux variability using spaceborne sensors is discussed. Particular attention is given to the microwave sensors which have all weather capability. The retrieval of surface layer humidity, of wind speed and interfacial humidity, and of sensible heat flux are discussed. Both the indirect retrieval and direct retrieval of latent heat flux are considered.
    Keywords: METEOROLOGY AND CLIMATOLOGY
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  • 8
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    Experimental investigation of oscillating cascade aerodynamics (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A series of experiments are performed in the NASA Lewis Transonic Oscillating Cascade Facility to provide fundamental data quantifying the high subsonic and transonic steady and oscillating aerodynamics of a biconvex airfoil cascade at realistic reduced frequency values for all interblade phase angles. This is accomplished by developing and utilizing an unsteady aerodynamic influence-coefficient technique in which only one cascaded airfoil is oscillated at a time. The vector summation of the resulting airfoil-surface unsteady pressures (measured on a dynamically instrumented airfoil) makes it possible to determine the unsteady aerodynamics of an equivalent cascade with all airfoils oscillating at any specified interblade phase angle.
    Keywords: AERODYNAMICS
    Type: Journal of Aerospace Power (ISSN 1000-8055); 5; 275-282
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  • 9
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    Ideal efficiency of propellers - Theodorsen revisited (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Theodorsen's 1948 analog evaluation of the parameters governing the ideal (friction-free) efficiency of propellers is updated and extended by computer. The results are presented both in his format and in a much more convenient one by Kramer that avoids iteration: curves of power coefficient at constant ideal efficiency are plotted vs propeller advance coefficient. The curves for a wide range of blade numbers are collapsed into just three sets (with some approximation) by use of multiple, shifted (and distorted) abscissae scales. Along with an overview of Theodorsen's theory, analytic asymptotic results at low and high advance coefficients are given. At the low end, the disagreement with actuator disk theory is given support and physical interpretation. At the high end, exact agreement is found with the thrust of a slender twisted delta propeller.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 27; 810-819
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  • 10
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    Supersonic far-field boundary conditions for transonic small-disturbance theory (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 27; 764-770
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  • 11
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    Evolution of tropical plumes in VAS water vapor imagery (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Synoptic scale tropical plumes are analyzed using satellite data and outgoing longwave radiation data. The evolution of plumes is described and their precursor signals are examined. The horizontal moisture patterns of the plumes are compared with nonplume climatology, and the predictability of plumes based solely on satellite imagery is assessed. The results show that a plume evolves as a stationary, tropical, dry or moist dipole, separated by an exceptionally strong cloud or moisture gradient. Tropical plume evolution is accompanied by a systematic drying of the tropical eastern Pacific atmosphere before development, and moistening and increased cloudiness with development.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Monthly Weather Review (ISSN 0027-0644); 118; 1758-176
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  • 12
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    Computational challenge - Euler solution for ellipses (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The present treatment of the inviscid flow past an ellipse via the numerical solution of the Euler equations yields a lifting solution for any combination of grid and/or angle of attack which is nonsymmetric, in order to illustrate the CFD challenge posed by this unusual flow behavior. The results obtained call into question the general capability and validity of numerical Euler results in the realm of conventional difference methods; specifically, the mechanism generating lifting results is not understood, and the problem's resolution is not yet in sight.
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 28; 1703
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  • 13
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    Oscillating cascade aerodynamics by an experimental influence coefficient technique (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Propulsion and Power (ISSN 0748-4658); 6; 612-620
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  • 14
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    Outer-layer manipulators for turbulent drag reduction (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The last ten years have yielded intriguing research results on aerodynamic boundary outer-layer manipulators as local skin friction reduction devices at low Reynolds numbers; net drag reduction device systems for entire aerodynamic configurations are nevertheless noted to remain elusive. Evidence has emerged for dramatic alterations of the structure of a turbulent boundary layer which persist for long distances downstream and reduce wall shear as a results of any one of several theoretically possible mechanisms. Reduced effectiveness at high Reynolds numbers may, however, limit the applicability of outer-layer manipulators to practical aircraft drag reduction.
    Keywords: AERODYNAMICS
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  • 15
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    Applied aspects of laminar-flow technology (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An account is given of the development status and performance levels achieved with natural laminar flow (NLF), extended wing chord laminar flow control (LFC), and hybrid laminar flow control (HLFC) concepts combining NLF and partial-chord LFC in the leading-edge region. Attention is given to NLF wing structure construction methods capable of achieving the requisite surface-irregularity tolerances, LFC through wing surface suction slots or perforated skins, and the deleterious effects of insects, ice crystals, and noise disturbance inputs on the ability of NLF, LFC, and HLFC wings to maintain effective laminar flow operation.
    Keywords: AERODYNAMICS
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  • 16
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    Satellite observations of instability in the middle atmosphere (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Data from the Limb Infrared Monitor of the Stratosphere (LIMS) have been used to define zonally averaged basic-state temperature and zonal wind fields in the middle atmosphere for several periods during the winter of 1978-79. This basic state has been used to calculate the phase speeds, growth rates, and spatial structures of unstable modes using a linear, quasigeostrophic model. These results have been compared with temperature and ozone variance amplitudes from a spectral analysis of the same LIMS data. The comparison indicates that there is a close match between phase speeds for the most rapidly growing modes predicted by the model and phase speeds for statistically significant temperature and ozone variances. Both calculated and observed modes tend to be limited in latitudinal extent to a few tens of degrees and in vertical extent to about 10 km. These modes also tend to be nondispersive. Examples are given for the Southern Hemisphere near 0.25 mb (60 km) and for low latitudes of the Northern Hemisphere near 15 mb (30 km).
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 47; 1065-107
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  • 17
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    Numerical simulation of three-dimensional transonic flows (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The three-dimensional flow over a projectile has been computed using an implicit, approximately factored, partially flux-split algorithm. A simple composite grid scheme has been developed in which a single grid is partitioned into a series of smaller grids for applications which require an external large memory device such as the SSD of the CRAY X-MP/48 or multi-tasking. The accuracy and stability of the composite grid scheme have been tested by numerically simulating the flow over an ellipsoid at an angle of attack and comparing the solution with a single-grid solution. The flow field over a projectile at M = 0.96 and 1.1, and 4-deg angle of attack has been computed using a fine grid and compared with experiment.
    Keywords: AERODYNAMICS
    Type: International Journal for Numerical Methods in Fluids (ISSN 0271-2091); 10; 855-873
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  • 18
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    Least-squares finite element methods for compressible Euler equations (1990)
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    Publication Date: 2011-08-19
    Description: A method based on backward finite differencing in time and a least-squares finite element scheme for first-order systems of partial differential equations in space is applied to the Euler equations for gas dynamics. The scheme minimizes the L-sq-norm of the residual within each time step. The method naturally generates numerical dissipation proportional to the time step size. An implicit method employing linear elements has been implemented and proves robust. For high-order elements, computed solutions based on the L-sq method may have oscillations for calculations at similar time step sizes. To overcome this difficulty, a scheme which minimizes the weighted H1-norm of the residual is proposed and leads to a successful scheme with high-degree elements. Finally, a conservative least-squares finite element method is also developed. Numerical results for two-dimensional problems are given to demonstrate the shock resolution of the methods and compare different approaches.
    Keywords: AERODYNAMICS
    Type: International Journal for Numerical Methods in Fluids (ISSN 0271-2091); 10; 557-568
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  • 19
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    Cascade aerodynamic gust response including steady loading effects (1990)
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    Publication Date: 2011-08-19
    Description: To predict the unsteady convected gust aerodynamic response of a cascade comprised of arbitrary thick and cambered aerofoils in an incompressible, inviscid, flow field, a complete first-order model is formulated. The flow is analyzed by considering a periodic flow channel. The velocity potential is separated into steady and unsteady harmonic components, each described by a Laplace equation. The strong dependence of the unsteady aerodynamics on the steady effects of aerofoil and cascade geometry and incidence angle is manifested in the coupling of the unsteady and steady flow fields through the unsteady boundary conditions. Analytical solutions in individual grid elements of a body-fitted computational grid are then determined, with the complete solution obtained by assembly of these local solutions. The validity and capabilities of this model and solution technique are then demonstrated by analyzing the steady and unsteady aerodynamics of both theoretical and experimental cascade configurations.
    Keywords: AERODYNAMICS
    Type: International Journal for Numerical Methods in Fluids (ISSN 0271-2091); 10; 285-303
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  • 20
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    Shear-layer-edge interaction - Simulation by finite-area vortices (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The impingement of a row of finite-area vortices on an edge is presently used to efficiently simulate the shear layer/edge interaction, yielding support for the hypothesis that the pressure waves emitted from an impingement edge are generated by the vortices/edge interaction. A parametric application of this method shows that pressure wave amplitude is a function of the length of the succession of vortices and that frequency of their release; this amplitude decreases with decreasing vortex spacing while succession length remains constant, or when succession length decreases while the number of vortices remains constant.
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 28; 1557-156
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  • 21
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    Experimental investigation of multielement airfoil ice accretion and resulting performance degradation (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 27; 679-691
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  • 22
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    Sun and dust versus greenhouse gases - An assessment of their relative roles in global climate change (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Many mechanisms, including variations in solar radiation and atmospheric aerosol concentrations, compete with anthropogenic greenhouse gases as causes of global climate change. Comparisons of available data show that solar variability will not counteract greenhouse warming and that future observations will need to be made to quantify the role of tropospheric aerosols, for example.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Nature (ISSN 0028-0836); 346; 713-719
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  • 23
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    Efficient cell-vertex multigrid scheme for the three-dimensional Navier-Stokes equations (1990)
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 28; 1464-147
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  • 24
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    Strake camber and thickness design procedure for low alpha supersonic flow (1990)
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 27; 481-487
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  • 25
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    Transitions from Hadley to Rossby flows in internally forced rotating spherical systems (1990)
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    Publication Date: 2011-08-19
    Description: The possibility of global-scale transitions between the Hadley and Rossby atmospheric regimes is investiated using a simple three-dimensional rotating spherical model without a boundary layer structure, bottom topography, or cumulus friction, and the expected occurrence of the Hadley to Rossby transition is demonstrated. It is shown that a transition from Hadley flow to wavenumber-5 Rossby flow is preferred, in agreement with standard baroclinic instability results. This result gives a reasonable Rossby wave bifurcation from the Hadley solution. For the cases examined, it was found that the upper symmetric Hadley regime does not exist and that the Hadley to Rossby transition depends on the values of the eddy viscosities.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 47; 1041-105
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  • 26
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    A numerical study of the onset of baroclinic instabilities in spherical geometry (1990)
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    Publication Date: 2011-08-19
    Description: The onset of instabilities in a fluid contained in a rotating hemispherical shell, driven by thermal gradients imposed upon the hemispherical boundaries and by a spherically symmetric radial body force, is numerically studied. Computations are presented for a range of Taylor and thermal Rossby numbers. The analysis indicates the presence of an instability dependent upon the spherically radial gravity alone when the warmest temperatures are at the pole and an additional centrifugal buoyant instability for weak imposed gravity and fast rotation when the temperature decreases poleward.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Geophysical and Astrophysical Fluid Dynamics (ISSN 0309-1929); 52; 25-43
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  • 27
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    A simple two-system-parameter model for surface-effected warming of the planetary boundary layer (1990)
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    Publication Date: 2011-08-19
    Description: The transabsorptivity concept which specifies the heat input into the PBL resulting from surface-atmosphere interactions is discussed. This concept is examined in terms of governing equations, and transabsorptivity is defined as the product of the surface absorptivity and the transfer efficiency. It is proposed that the climatic effects of surface changes be formulated in terms of changes in the transabsorptivity. A diagram of the surface-atmosphere interactions is provided.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Boundary-Layer Meteorology (ISSN 0006-8314); 51; 3, Ma; 213-227
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  • 28
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    Nonlinear effects in the two-dimensional adaptive-wall outer-flow problem (1990)
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    Publication Date: 2011-08-19
    Description: The importance of nonlinear effects to the solution of two-dimensional adaptive-wall outer-flow problems is presently evaluated by comparing outer-flow solutions computed on the basis of the transonic small perturbation equations with solutions based on the linear Prandtl-Glauert equation. Both methods are applied to simulated measurements of transonic flow past a two-dimensional airfoil in free air. Nonlinear effects are found to be important in the outer-flow solution only where the outer flow included supersonic flow.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 27; 475-477
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  • 29
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    Navier-Stokes analyses of the redistribution of inlet temperature distortions in a turbine (1990)
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Propulsion and Power (ISSN 0748-4658); 6; 276-282
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  • 30
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    Suggestions for the measurement and derivation of fluxes and flux divergences from a satellite (1990)
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    Publication Date: 2011-08-19
    Description: Consideration is given to the determination of the optimal bands for measuring and deriving the total outgoing longwave radiation (OLR), surface downward flux (SDF), and cooling rates (CRs) using linear regression. The optimal bands are determined from scatter plots of total fluxes and cooling rates associated with the various bands. It is found that the best band for OLR is between 800 and 1200/cm, while the best band for SDF is between 500 and 660/cm or between 660 and 800/cm. For CRs, it is shown that the best band is also between 660 and 800/cm. It is noted that the AVHRR OLR is damped compared with the Nimbus-7 earth radiation budget (ERB) OLR derived from the broadband, narrow FOV ERB instrument.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 5257-527
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  • 31
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    Comparison of nonequilibrium viscous-shock-layer solutions with shuttle heating measurement (1990)
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Thermophysics and Heat Transfer (ISSN 0887-8722); 4; 162-169
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  • 32
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    Comparison between experimental and numerical results for a research hypersonic aircraft (1990)
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 27; 300-305
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  • 33
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    A comparison of Solar Mesosphere Explorer and Stratosphere Aerosol and Gas Experiment II ozone densities near the stratopause (1990)
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    Publication Date: 2011-08-19
    Description: Ozone measurements made by the SME UV Spectrometer and the Stratosphere Aerosol and Gas Experiment II (SAGE II) spectometer are compared at 1.0 mbar for the time period from October 1984 to December 1986, using a model of the diurnal variation of ozone to correct for the difference in local times of the two measurements. The absolute values of the ozone mixing ratio measured by the two spectrometers were found to agree to better than 5 percent, with no significant divergence between the instruments. It is concluded that, since the SAGE II data are not dependent on the absolute calibration of the instrument, these data can be used as time-dependent 'ground truth' measurements for comparisons with other instruments.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 3533-353
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  • 34
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    Boundary layer manipulators at high Reynolds numbers (1990)
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    Publication Date: 2011-08-19
    Description: Airfoil large-eddy breakup (LEBU) devices were tested on an axisymmetric body in the Langley Two Tank up to speeds of 50 ft/sec. NACA-0009, NACA-2412, E-193, and Clark Y contours were tested in single and tandem configurations. At the higher Reynolds numbers local skin friction downstream of the devices showed minimal reductions O (10 percent) and total body drag was increased 1 to 3 percent. At lower Reynolds numbers skin-friction reductions as large as 25 percent were measured and total body drag tended toward net reductions. The loss of effectiveness with increasing Reynolds number of conventional, outer layer devices suggests a decoupling of the outer and inner scales in high Reynolds number turbulent boundary layers.
    Keywords: AERODYNAMICS
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  • 35
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    Static aeroelastic analysis of a three-dimensional oblique wing (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A capability to perform static aeroelastic analyses of an oblique wing at arbitrary skew positions was developed based on the framework of the MSC/NASTRAN static aeroelastic analysis. By means of DMAP alterations, a portion of the subsonic static aeroelastic analysis scheme was modified to insert an aerodynamic influence coefficient matrix created externally by the NASA-Ames aerodynamic panel codes. The modified scheme can cover the subsonic as well as the supersonic range for both symmetric and asymmetric configurations. Static aeroelastic responses of the oblique wing are studied at two skew angles and, in particular, the capability to calculate 3D camber effects on the aerodynamic properties of the wing is investigated. Various aerodynamic coefficients of the rigid oblique wing are computed for two Mach numbers, 0.7 and 1.4, and the angle of attack is varied from -5 through 15 deg. Also, the wing flexibility effects on the aerodynamic coefficients and the displacement are examined at a Mach number of 0.7 for a 45-deg swept wing.
    Keywords: AERODYNAMICS
    Type: Computing Systems in Engineering (ISSN 0956-0521); 1; 2-4,
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  • 36
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    Vortical flow computations on swept flexible wings using Navier-Stokes equations (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 28; 2077-208
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  • 37
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    Deep optically thin cirrus clouds in the polar regions. I - Infrared extinction characteristics (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The spectral data obtained by the infrared interferometer Spectrometer (IRIS) flown on Nimbus 4 satellite in 1970 indicated the existence of optically thin ice clouds in the upper troposphere that probably extended into lower stratosphere, in the polar regions, during winter and early spring. The spectral features of these clouds differ somewhat from that of the optically thin cirrus clouds in the tropics. From theoretical simulation of the infrared spectra in the 8-25 micron region, it is inferred that these polar clouds have a vertical stratification in particle size, with larger particles (about 12 microns) in the bottom of the cloud and smaller ones (less than 1 micron) aloft. Radiative transfer calculations also suggest that the equivalent ice-water content of these polar clouds is of the order of 1 mg/sq cm.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Applied Meteorology (ISSN 0894-8763); 29; 1313-132
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  • 38
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    Cirrus structure and radiative parameters from airborne lidar and spectral radiometer observations - The 28 October 1986 FIRE study (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A description is presented of cirrus based on results from a FIRE observation flight in central Wisconsin on October 28, 1986. Cirrus structure and radiative parameters as determined by the ER-2 lidar and imaging spectral radiometers are presented. From the lidar observations a complex structure was shown with differing cloud layers extending over six kilometers of altitude range. Both thin and dense cirrus layers were present and mixed phase clouds were found at lower altitudes. As indicated by the cloud structure, precipitation of crystals from high, but vertically thin, layers produces a significant fraction of the lower cirrus. Multiple layers should be considered as normal for cirrus formations. It is noted that the cloud height is an important factor for satellite cloud retrievals and cloud climatology.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Monthly Weather Review (ISSN 0027-0644); 118; 2329-234
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  • 39
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    An increase of early rains in southern Israel following land-use change? (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Rains at the onset of the October-April rainy season in southern Israel have steeply increased in the last 25 years relative to the previous 20 years, and are accompanied by an appreciable general increase of rainy-season rainfall. This increase in precipitation is specifically attributable to an intensification of the convection and advection processes due to afforestation and increased cultivation-induced enhancement of the daytime sensible heat flux from the generally dry surface; the enhancement proceeds from both the reduced surface albedo and the reduced soil heat flux in October, when insolation is strong. Greater daytime convection can lead to penetration of inversions capping the planetary boundary layer, while strengthened advection can furnish moist air from the Mediterranean.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Boundary-Layer Meteorology (ISSN 0006-8314); 53; 333-351
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  • 40
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    Numerical simulation of an F-16A at angle of attack (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 27; 886-892
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  • 41
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    Combined effects of nose bluntness and surface perturbations on asymmetric flow past slender bodies (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 27; 909
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  • 42
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    Estimation of synoptic fields of middle atmosphere parameters from Nimbus-7 LIMS profile data (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The most widely used version of the Nimbus-7 middle atmosphere dataset is the set of high quality, daily, and zonal Fourier coefficients that resolve information out to six wavenumbers at 12 UTC. A Kalman filter algorithm was applied to the original profile data in order to generate those fields for the data archive or LAMAT product. The characteristics and implementation of the algorithm are described in some detail, along with examples of the output for each of the LIMS parameters.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Atmospheric and Oceanic Technology (ISSN 0739-0572); 7; 689-705
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  • 43
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    Vertical structure and characteristics of 23-60 day (zonal) oscillations over the tropical latitudes during the winter months of 1986 - Results of equatorial wave campaign-II (1990)
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    Publication Date: 2011-08-19
    Description: Results are presented of the equatorial wave campaign-II, a meteorological rocket study which was part of the Indian Middle Atmosphere Program. The equatorial wave campaign-II was conducted from Shar, India (13.7 deg N, 80.2 deg E) from January 15-February 28, 1986. By means of high altitude balloon and the RH-200 meteorological rocket, winds were measured from ground level up to 60 km altitude once each day during the 45-day period. The oscillation frequencies of the deviations in the east-west component of the winds from their mean at each 1-km height interval are obtained by the maximum entropy method. The phases and amplitudes of these frequencies are determined by use of the least squares method on the wind variation time series. Enhanced wave activity is shown to take place in the troposphere and lower mesosphere. The tropospheric waves observed suggest themselves to be Rossby waves of extratropical origin penetrating to tropical latitudes. The observed stratospheric/mesospheric waves appear to emanate from a source around the stratopause.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: (ISSN 0253-4126); 99; 413-423
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  • 44
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    Parameterization of eddy sensible heat transports in a zonally averaged dynamic model of the atmosphere (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A Charney-Branscome based parameterization has been tested as a way of representing the eddy sensible heat transports missing in a zonally averaged dynamic model (ZADM) of the atmosphere. The ZADM used is a zonally averaged version of a general circulation model (GCM). The parameterized transports in the ZADM are gaged against the corresponding fluxes explicitly simulated in the GCM, using the same zonally averaged boundary conditions in both models. The Charney-Branscome approach neglects stationary eddies and transient barotropic disturbances and relies on a set of simplifying assumptions, including the linear appoximation, to describe growing transient baroclinic eddies. Nevertheless, fairly satisfactory results are obtained when the parameterization is performed interactively with the model. Compared with noninteractive tests, a very efficient restoring feedback effect between the modeled zonal-mean climate and the parameterized meridional eddy transport is identified.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 47; 2475-248
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  • 45
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    On the inviscid acoustic-mode instability of supersonic shear flows. I - Two-dimensional waves (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The same previously utilized methods to study acoustic-mode instability in supersonic boundary layers are applied to free shear layers, and new calculations are derived for boundary layers with cooling and suction. The linear inviscid stability theory is employed to calculate spatial amplification rates at Mach 3 for the sinuous and varicose modes of a single wake flow and a single jet flow, each made up of the same mixing-layer profile plus a central region of uniform flow. It is shown that along with sequences of sinuous and varicose unstable modes clearly identifiable as acoustic modes, both of these flows, unlike the boundary layer, have a lowest sinuous mode that is the most unstable.
    Keywords: AERODYNAMICS
    Type: Theoretical and Computational Fluid Dynamics (ISSN 0935-4964); 2; 2, 19
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  • 46
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    The analysis and simulation of compressible turbulence (1990)
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    Publication Date: 2011-08-19
    Description: Compressible turbulent flows at low turbulent Mach numbers are considered. Contrary to the general belief that such flows are almost incompressible (i.e., the divergence of the velocity field remains small for all times), it is shown that even if the divergence of the initial velocity field is negligibly small, it can grow rapidly on a nondimensional time scale which is the inverse of the fluctuating Mach number. An asymptotic theory which enables one to obtain a description of the flow in terms of its divergence-free and vorticity-free components has been developed to solve the initial-value problem. As a result, the various types of low Mach number turbulent regimes have been classified with respect to the initial conditions. Formulae are derived that accurately predict the level of compressibility after the initial transients have disappeared. These results are verified by extensive direct numerical simulations of isotropic turbulence.
    Keywords: AERODYNAMICS
    Type: Theoretical and Computational Fluid Dynamics (ISSN 0935-4964); 2; 2, 19; 73-95
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  • 47
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    Behavior of deep convective clouds in the tropical Pacific deduced from ISCCP radiances (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The characteristic features, the diurnal cycle, and the spatial distribution of deep convection over the equatorial Pacific and the relationship of deep convection to SST and surface-wind convergence were examined using a combined visible-IR (VS-IR) threshold method and an IR-only threshold method for diagnosing deep convection clouds (DCCs). Results suggest that deep convection is latitudinally confined to a much smaller spatial scale than that suggested by maps of outgoing long-wave radiation. The results suggested that there are two types of relationships between deep convection, SST, and surface-wind convergence: the west Pacific type and the east Pacific type. The latter relationship is observed in the east Pacific only when SST is not abnormally warm.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Climate (ISSN 0894-8755); 3; 1129-115
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  • 48
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    Global atmospheric temperature monitoring with satellite microwave measurements - Method and results 1979-84 (1990)
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    Publication Date: 2011-08-19
    Description: This paper describes a method for determining global atmospheric-temperature anomalies by means of satellite microwave radiometry. It is shown that microwave measurements of molecular oxygen thermal emission by the Microwave Sounding Units (MSUs) flying aboard the NOAA-6 and NOAA-7 can be used to monitor tropospheric temperature anomalies on global basis to a high level of precision. Comparisons between monthly MSU-derived hemispheric temperature anomalies with those computed from surface thermometer data show a very good agreement over the United States, although not for the hemispheres, especially the Southern Hemisphere. In this latter case, the poor agreement is ascribed to weaker thermal coupling between the ocean and the deep troposphere than that over the U.S. Annual anomalies for the hemispheres exhibit better correlations than do monthly anomalies.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Climate (ISSN 0894-8755); 3; 1111-112
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  • 49
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    Three-dimensional viscous rotor flow calculations using a viscous-inviscid interaction approach (1990)
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    Publication Date: 2011-08-19
    Description: A three-dimensional viscous-inviscid interaction analysis was developed to predict the performance of rotors in hover and in forward flight at subsonic and transonic tip speeds. The analysis solves the full-potential and boundary-layer equations by finite-difference numerical procedures. Calculations were made for several different model rotor configurations. The results were compared with predictions from a two-dimensional integral method and with experimental data. The comparisons show good agreement between predictions and test data.
    Keywords: AERODYNAMICS
    Type: Vertica (ISSN 0360-5450); 14; 3, 19; 417-427
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  • 50
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    Vortex-dominated conical-flow computations using unstructured adaptively-refined meshes (1990)
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 28; 1925-193
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  • 51
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    Improvements to a nonequilibrium algebraic turbulence model (1990)
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    Publication Date: 2011-08-19
    Description: It has been noted that while the nonequilibrium turbulence model of Johnson and King (1985, 1987) performed significantly better than alternative methods, differences between predicted and observed shock locations for certain weak interactions are produced due to a defficiency in the model's inner eddy viscosity formulation. A novel formulation for the model is presented which removes this deficiency, while satisfying the law of the wall for adverse pressure-gradient conditions better than either the original formulation or mixing-length theory.
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 28; 2000-200
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  • 52
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    Determination of cloud liquid water content using the SSM/I (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: As part of a calibration/validation effort for the special sensor microwave/imager (SSM/I), coincident observations of SSM/I brightness temperatures and surface-based observations of cloud liquid water were obtained. These observations were used to validate initial algorithms and to derive an improved algorithm. The initial algorithms were divided into latitudinal-, seasonal-, and surface-type zones. It was found that these initial algorithms, which were of the D-matrix type, did not yield sufficiently accurate results. The surface-based measurements of channels were investigated; however, the 85V channel was excluded because of excessive noise. It was found that there is no significant correlation between the SSM/I brightness temperatures and the surface-based cloud liquid water determination when the background surface is land or snow. A high correlation was found between brightness temperatures and ground-based measurements over the ocean.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); 28; 817-822
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  • 53
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    Explicit thermochemical nonequilibrium algorithm applied to compute three-dimensional aeroassist flight experiment flowfields (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 27; 545-553
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  • 54
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    Seasonal variation of cloud radiative forcing derived from the Earth Radiation Budget Experiment (1990)
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    Publication Date: 2011-08-19
    Description: The impact of clouds on the earth's radiation balance is assessed in terms of longwave, shortwave, and net cloud forcing by using monthly averaged clear-sky and cloudy-sky flux data derived from the NASA Earth Radiation Budget Experiment (ERBE). Emphasis is placed on regional measurements, regional cloud forcing, zonal cloud forcing, and snow and ice contributions. It is shown that the global mean cooling varied from 14 to 21 W/sq m between April 1985 and January 1986; hemispherically, the longwave and shortwave cloud forcing nearly cancel each other in the winter hemisphere, while in the summer the negative shortwave cloud forcing is significantly lower than the longwave cloud forcing, producing a strong cooling. The ERBE data reveal that globally, hemispherically, and zonally, clouds have a significant effect on the radiative heating gradients.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 18687-18
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  • 55
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    Airborne flux measurements and budget estimates of trace species over the Amazon Basin during the GTE/ABLE 2B expedition (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: In situ airborne measurements of turbulent heat, moisture, momentum, ozone, and carbon monoxide fluxes in a convective boundary layer were obtained over a tropical rain forest between 1100 and 1630 LT on May 4, 1987. The aircraft flight path was chosen so as to fly over the tower site at the Ducke Forest Reserve near Manaus, Amazonas, Brazil. Both turbulence statistics and mean quantities were used to study the budgets of heat, water vapor, ozone, and carbon monoxide. The ozone budget study shows an accumulation rate in the boundary layer of 0.3 + or - 0.2 ppbv/h. The surface resistance to ozone during this flight was determined to be 0.06 + or - 0.03 s/cm, while the aerodynamic resistance was 0.14-0.17 s/cm. Results from the CO budget analysis show a midday accumulation rate of 0.6 + or - 0.3 ppbv/h in the Amazonian boundary layer. The evidence suggests production of CO in the PBL. A source of CO may exist below the lowest flight level (about 150 m), although it was not possible to determine what part of the flux at flight level was due to chemical production and what part may be due to surface emission.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 16875-16
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  • 56
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    Unsteady Euler airfoil solutions using unstructured dynamic meshes (1990)
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 28; 1381-138
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  • 57
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    Experimental observations of two-dimensional blade-vortex interaction (1990)
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 28; 1353-135
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  • 58
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    Multigrid solution of the Navier-Stokes equations on triangular meshes (1990)
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    Publication Date: 2011-08-19
    Description: A Navier-Stokes algorithm for use on unstructured triangular meshes is presented. Spatial discretization of the governing equations is achieved using a finite element Galerkin approximation, which can be shown to be equivalent to a finite volume approximation for regular equilateral triangular meshes. Integration steady-state is performed using a multistage time-stepping scheme, and convergence is accelerated by means of implicit residual smoothing and an unstructured multigrid algorithm. Directional scaling of the artificial dissipation and the implicit residual smoothing operator is achieved for unstructured meshes by considering local mesh stretching vectors at each point. The accuracy of the scheme for highly stretched triangular meshes is validated by comparing computed flat-plate laminar boundary layer results with the well known similarity solution, and by comparing laminar airfoil results with those obtained from various well-established structured quadrilateral-mesh codes. The convergence efficiency of the present method is also shown to be competitive with those demonstrated by structured quadrilateral-mesh algorithms.
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 28; 1415-142
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  • 59
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    Determination of atmospheric optical properties during the First International Satellite Land Surface Climatology Project Field Experiment (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 27; 373-379
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  • 60
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    Flowfield and vehicle parameter influence on hypersonic heat transfer and drag (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 27; 361-368
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  • 61
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    Origin of low frequency (intraseasonal) oscillations in the tropical atmosphere. III - Monsoon dynamics (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The issue of the interaction of the monsoon large-scale circulation and intraseasonal oscillations is addressed, showing that, as a result of the interaction of the large scale monsoon flow with the near-equatorial intraseasonal oscillation, unstable baroclinic disturbances are generated over the monsoon region. From a linear stability analysis of quasi-geostrophic motion in a two-level model, it is shown that the westward propagating disturbances generated over the monsoon region are the manifestation of heat-induced unstable Rossby waves. The instability is favored in the region with large vertical wind shear and reduced effective static stability. The monsoon large scale circulation over India and southeast Asia and the plentiful supply of moisture in the region appear to be favorable for the development of these unstable waves.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 47; 1443-146
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  • 62
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    Meteorological conditions during the summer 1986 CITE 2 flight series (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An overview of meteorological conditions during the NASA Global Tropospheric Experiment/Chemical Instrumentation Testing and Evaluation (GTE/CITE 2) summer 1986 flight series is presented. Computer-generated isentropic trajectories are used to trace the history of air masses encountered along each aircraft flight path. The synoptic-scale wind fields are depicted based on Montgomery stream function analyses. Time series of aircraft-measured temperature, dew point, ozone, and altitude are shown to depict air mass variability. Observed differences between maritime tropical and maritime polar air masses are discussed.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 10055-10
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  • 63
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    Potential evapotranspiration and the likelihood of future drought (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The possibility that the greenhouse warming predicted by the GISS general-circulation model and other GCMs could lead to severe droughts is investigated by means of numerical simulations, with a focus on the role of potential evapotranspiration E(P). The relationships between precipitation (P), E(P), soil moisture, and vegetation changes in GCMs are discussed; the empirically derived Palmer drought-intensity index and a new supply-demand index (SDDI) based on changes in P - E(P) are described; and simulation results for the period 1960-2060 are presented in extensive tables, graphs, and computer-generated color maps. Simulations with both drought indices predict increasing drought frequency for the U.S., with effects already apparent in the 1990s and a 50-percent frequency of severe droughts by the 2050s. Analyses of arid periods during the Mesozoic and Cenozoic are shown to support the use of the SDDI in GCM drought prediction.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 9983-100
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  • 64
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    Aircraft microwave observations and simulations of deep convection from 18 to 183 GHz. II - Model results (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: In this June 29, 1986 case study, a radiative transfer model is used to simulate the aircraft multichannel microwave brightness temperatures presented in the Adler et al. (1990) paper and to study the convective storm structure. Ground-based radar data are used to derive hydrometeor profiles of the storm, based on which the microwave upwelling brightness temperatures are calculated. Various vertical hydrometeor phase profiles and the Marshall and Palmer (M-P, 1948) and Sekhon and Srivastava (S-S, 1970) ice particle size distributions are experimented in the model. The results are compared with the aircraft radiometric data. The comparison reveals that the M-P distribution well represents the ice particle size distribution, especially in the upper tropospheric portion of the cloud; the S-S distribution appears to better simulate the ice particle size at the lower portion of the cloud, which has a greater effect on the low-frequency microwave upwelling brightness temperatures; and that, in deep convective regions, significant supercooled liquid water (about 0.5 g/cu m) may be present up to the -30 C layer, while in less convective areas, frozen hydrometeors are predominant above -10 C level.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Atmospheric and Oceanic Technology (ISSN 0739-0572); 7; 392-410
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  • 65
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    Flow visualization studies of the Mach number effects on dynamic stall of an oscillating airfoil (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 27; 516-522
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  • 66
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    Aerothermodynamics and transition in high-speed wind tunnels at NASA Langley (1990)
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    Publication Date: 2011-08-19
    Description: The evolutionary development of subsonic, supersonic, and hypersonic wind tunnels for the study of aerodynamic, aerothermodynamic, and fluid-dynamic characteristics of the flow about models, including transition from laminar to turbulent boundary layers, is discussed. Currently, three supersonic and seven hypersonic wind tunnels are operational at Langley, and two additional tunnels are scheduled to become operational by 1990. In the present work, an effort is made to provide a 'tour'of selected supersonic and hypersonic wind tunnels at NASA-Langley used for aerodynamic and aerothermodynamic testing of models, and to present the evolution of quiet-tunnel technology at this facility over the last decade. It is noted that upgrades to the hypersonic facilities complex are underway in order to provide the high flow quality and improved data accuracy required to calibrate advanced computational fluid-dynamic computer codes. Also to be provided are increased productivity required for configuration development and improved reliability to support major hypersonic programs in an efficient and timely manner.
    Keywords: AERODYNAMICS
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    On the sensitivity of a residual circulation model to differences in input temperature data (1990)
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    Publication Date: 2011-08-19
    Description: The residual mean circulation (RMC) formulation of zonally averaged transport in the middle atmosphere produces a circulation which depends on the distributions of net diabatic heating and temperature. Such circulations are from two temperature data sets, using the same radiative transfer code (Rosenfield et al. 1987). These circulations are then used to transport N2O in a photochemical model. The circulations and the resulting N2O distributions are notably different during the Northern Hemisphere winter, with that based on the NMC temperatures producing too much upward transport in the tropical stratosphere, as judged by comparison with the stratospheric and mesoscale sounder data. The experiment demonstrates that model calculations, in general, and perturbation assessments, in particular, are likely to be quite sensitive to the choice of input temperature data (where this is not computed self-consistently). It also reveals what appears to be a seasonally dependent bias in NMC zonally averaged temperatures with respect to those obtained from the LIMS instrument during 1978/1979.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 873-882
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  • 68
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    Computation of hypersonic flow through a narrow expansion slot (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 28; 229-235
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  • 69
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    An analysis of the threshold method for measuring area-average rainfall (1990)
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    Publication Date: 2011-08-19
    Description: Experimental evidence shows that the area-average rain rate and the fractional area covered by rain rate exceeding a fixed threshold are highly correlated; that is, are highly linearly related. A precise theoretical explanation of this fact is given. The explanation is based on the observation that rain rate has a mixed distribution, one that is a mixture of a discrete distribution and a continuous distribution. Under a homogeneity assumption, the slope of the linear relationship depends only on the continuous part of the distribution and as such is found to be markedly immune to parameter changes. This is illustrated by certain slope surfaces obtained from three specific distributions. The threshold level can be chosen in an optimal way by minimizing a certain distance function defined over the threshold range. In general, the threshold level should be not too far from the mean rain rate conditional on rain. The so-called threshold method advocates measuring rainfall from fractional area exploiting the observed linear relationship of the later with the area average rain rate. The method is potentially useful for the estimation of rainfall from space via satellites.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Applied Meteorology (ISSN 0894-8763); 29; 3-20
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  • 70
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    Multiple vortex ring model of the DFW microburst (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Aircraft (ISSN 0021-8669); 27; 163-168
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  • 71
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    Leading- and trailing-edge flaps on supersonic delta wings (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 27; 158-162
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  • 72
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    Effects of nonplanar outboard wing forms on a wing (1990)
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    Publication Date: 2011-08-19
    Description: It is possible for a constant span to obtain better aerodynamic performance from a wing with a nonplanar outboard wing form than from a wing with a planar outboard form, despite the added drag from the increased wetted area. Furthermore, the semispan rolling-moment characteristics indicate the lower wing-root bending moment for some nonplanar configurations. These conclusions are based on an experimental and computational investigation of the aerodynamic characteristics of planar and nonplanar outboard wing forms. Seven different configurations - planar rectangular, nonplanar rising arc, nonplanar drooping arc, planar sheared, sheared with dihedral, sheared with anhedral, and planar elliptical - were investigated for two different spans. Flow-visualization photographs indicate that there are three vortex systems associated with the sheared forms. The lower induced drag coefficients of nonplanar wings are believed to accrue from the movement of vorticity away from the center-of-span line, resulting, in some instances, in induced efficiencies higher than that of a planar elliptical wing. Flow surveys indicate that the effective span, as determined by the location of the tip vortex, might not be a sufficient yardstick of the induced performance of a nonplanar wing.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 27; 117-122
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  • 73
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    Analysis of extreme wind shear (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 27; 21-24
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  • 74
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    Analysis of selected data from the triservice missile data base (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 27; 15-20
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  • 75
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    Surface pressure and streamline effects on laminar heating calculations (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 27; 9-14
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  • 76
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    Climate change and the middle atmosphere. I - The doubled CO2 climate (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The effect of doubling the atmospheric content of CO2 on the middle-atmosphere climate is investigated using the GISS global climate model. In the standard experiment, the CO2 concentration is doubled both in the stratosphere and troposphere, and the SSTs are increased to match those of the doubled CO2 run of the GISS model. Results show that the doubling of CO2 leads to higher temperatures in the troposphere, and lower temperatures in the stratosphere, with a net result being a decrease of static stability for the atmosphere as a whole. The middle atmosphere dynamical differences found were on the order of 10-20 percent of the model values for the current climate. These differences, along with the calculated temperature differences of up to about 10 C, may have a significant impact on the chemistry of the future atmosphere, including that of stratospheric ozone, the polar ozone 'hole', and basic atmospheric composition.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 47; 475-494
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  • 77
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    Analysis of fully stalled compressor (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Propulsion and Power (ISSN 0748-4658); 6; 177-180
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  • 78
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    Climatologically tuned reflectivity-rain rate relations and links to area-time integrals (1990)
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    Publication Date: 2011-08-19
    Description: An effort is made to determine relationships between reflectivity (Z) and rain rate (R) which are tuned to the local climatology. The development of such relations was motivated by the need to understand the role of precipitation in controlling general circulation and in affecting such phenomena as ENSO. Attention is given to methods of deriving such relations and how they are linked to area integral rainfall measurements. In essence, the relation is tuned so that the probability distribution of reflectivity, P(Z), replicates that of R over some predetermined space-time climatic domain. Thus, the accurate measurement of the average R over any smaller domain depends on how closely the sampled P(Z) approximates the climatic P(Z). The probability matching method used is a modification of the approach of Calheiros and Zawadzki (1987) and Rosenfeld (1980). The technique is applied to data from Germany and the eastern tropical Atlantic (GATE).
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Applied Meteorology (ISSN 0894-8763); 29; 1120-113
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  • 79
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    Automated domain decomposition for computational fluid dynamics (1990)
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    Publication Date: 2011-08-19
    Description: Automation of flow-field zoning in two-dimensions is an important step towards easing the three-dimensional grid generation bottleneck in computational fluid dynamics. A knowledge-based approach works well, but several aspects of flow-field zoning make the use of such an approach challenging. A proposed model and language to describe the process of zoning a flow field are presented, followed by a discussion of the implementation of EZGrid, a knowledge-based two-dimensional (2-D) flow-field zoner. Results are shown for representative two-dimensional aerodynamic configurations. Finally, an approach to the evaluation of flow-field zonings is described and used to compare the performance of EZGrid with that of a human expert.
    Keywords: AERODYNAMICS
    Type: Computers and Fluids (ISSN 0045-7930); 18; 4, 19
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  • 80
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    Clear air turbulence as a response to meso- and synoptic-scale dynamic processes (1990)
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    Publication Date: 2011-08-19
    Description: The paper presents both the Roach equation for the rate of energy dissipation due to clear air turbulence and Richardson number tendencies in isentropic coordinates and examines the implications of these formulations to determine whether there is a dynamic interdependence between Ri and the nonturbulent deformation processes. The equation representing the ln(Ri) tendency is applied diagnostically to grids from an isentropic analysis of archived soundings. The evolution of the Richardson number fields over 12-hour time periods is examined using a mechanistic model. It is suggested that the application of the Roach equation for the turbulent dissipation rate should have a more restricted use. Analyses of the meso-alpha scale Richardson number and of the Richardson number tendency fields reveal a phase relationship consistent with the theoretical predictions.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Monthly Weather Review (ISSN 0027-0644); 118; 2228-224
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  • 81
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    Aerobrake aerothermodynamics (1990)
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    Publication Date: 2011-08-19
    Description: The status of aerothermodynamics research applicable to aerobrake and aeroassist vehicles is summarized. Techniques that use aerodynamic forces instead of retropropulsion to decelerate vehicles for orbit changes at Mars and upon return to earth from either the moon or Mars can reduce the initial mass required in LEO by as much as 60 percent, thus reducing the number and size of earth-to-orbit launch vehicles. However, several critical technologies must be developed in order to design aerobrakes that can withstand the aerodynamic forces and heating to which the entry vehicles will be subjected. Among these is aerothermodynamics. The ultimate goal is to develop and validate codes that can, by predicting aerobrake thermal environments, be used to select and size the thermal protection and supporting structures.
    Keywords: AERODYNAMICS
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  • 82
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    Precipitable water estimation from high-resolution split window radiance measurements (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A technique that uses the spatial variance of image brightness temperature to derive total column precipitable water is applied to high-resolution multispectral aircraft scanner data for the June 19, 1986 COHMEX day. The technique has several advantages over other approaches in that it requires only relative calibration accuracy, is less susceptible to instrument error, and does not directly use a priori information. Results indicate significant horizontal variability of precipitable water at the mesoscale. Precipitable water gradients of 6 mm per 10 km are not uncommon. The results verify well against special rawinsonde measurements and the ensuing cloud field development. While only applied to this specialized aircraft data, the applicability of the technique to operational AVHRR and VAS data is discussed.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Applied Meteorology (ISSN 0894-8763); 29; 863-877
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  • 83
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    In defense of Ertel's potential vorticity and its general applicability as a meteorological tracer (1990)
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    Publication Date: 2011-08-19
    Description: A potential vorticity theorem and its two summary statements published by Haynes and McIntyre are challenged conceptually by equations, discussions and examples. The apparent simplification proposed by the authors to convert from a mass to volume integral, i.e., by cancelling density against the specific volume in the potential vorticity, changes the physical significance of the integrand. It no longer is the potential vorticity. The resulting mean for either a bulk Eulerian or Lagrangian system is then not analogous to a mixing ratio and therefore not independent of the broad spectrum of internal waves, the independence that makes Ertel's potential vorticity so valuable either as a stratospheric tracer or as a predictive or diagnostic, large scale, meteorological variable.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 47; 2013-202
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  • 84
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    Development of high-lift wing modifications for an advanced capability EA-6B aircraft (1990)
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    Publication Date: 2011-08-19
    Description: NASA-Langley has been in a development program aimed at improvements of the EA-6B electronic countermeasures aircraft's maneuvering capabilities; one objective of this effort is the investigation of relatively simple wing design modifications which could yield improved low speed high lift performance with minimum degradation of higher-speed performance. Various two- and three-dimensional low speed and transonic CFD techniques have accordingly been used during the design effort, which involved leading-edge slat and trailing-edge flap contour evaluations by both computation and wind tunnel experiment. Significant low-speed maximum-lift enhancements were obtained without cruise-speed deterioration.
    Keywords: AERODYNAMICS
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  • 85
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    Computational analysis of rotor-stator interaction in turbomachinery using zonal techniques (1990)
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    Publication Date: 2011-08-19
    Description: The development of CFD zonal techniques which allow more intensive computational treatment in some regions than in others, in conjunction with robust, high-accuracy algorithms for the numerical solution of the Navier-Stokes equations, is presently shown to have facilitated the investigation of rotor-stator interactions in turbomachinery. Attention is given to integration schemes with two and three spatial dimensions, the conservative 'patched' and the nonconservative zonal boundary schemes, and such natural boundary conditions as those of the endwall, the stator inlet, the airfoil surface, and the rotor exit. Illustrative three-dimensional rotor-stator interaction calculations are presented.
    Keywords: AERODYNAMICS
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  • 86
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    Euler and potential computational results for selected aerodynamic configurations (1990)
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    Publication Date: 2011-08-19
    Description: A selection of CFD successes and failures is evaluated, on the basis of experimental data/CFD result correlations involving full-potential and Euler computations of the aerodynamics of four commercial transport wings and two low aspect ratio delta wings. An effort is made to ascertain optimum values for grid density and distribution, artificial dissipation, Courant-Friedrichs-Lewy number, enthalphy damping, and a multigrid scheme for each flow condition and configuration analyzed. It is demonstrated that CFD solutions can assist the experimentalist prior to a test by indicating the locations of high pressure gradients and projecting test condition limitations due to balance design limits.
    Keywords: AERODYNAMICS
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  • 87
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    An LDA investigation of the normal shock wave boundary layer interaction (1990)
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    Publication Date: 2011-08-19
    Description: Nonintrusive measurements have been made of two normal shock wave-boundary layer interactions. Two-dimensional measurements were made throughout the interaction region while three-dimensional measurements were made in the vicinity of the shock wave. The measurements were made in the corner of the test section of a continuous flow supersonic wind tunnel in which a normal shock wave had been stabilized. LDA, surface pressure measurement and flow visualization techniques were employed for two freestream Mach number test cases: 1.6 and 1.3. The former contained separated flow regions and a system of shock waves. The latter was found to be far less complicated. The reported results define the flowfield structure in detail for each case.
    Keywords: AERODYNAMICS
    Type: (ISSN 0379-380X); 2, 19
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  • 88
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    Cloud draft structure and trace gas transport (1990)
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    Publication Date: 2011-08-19
    Description: During the second Amazon Boundary Layer Experiment (ABLE 2B), meteorological observations, chemical measurements, and model simulations are utilized in order to interpret convective cloud draft structure and to analyze its role in transport and vertical distribution of trace gases. One-dimensional photochemical model results suggest that the observed poststorm changes in ozone concentration can be attributed to convective transports rather than photochemical production and the results of a two-dimensional time-dependent cloud model simulation are presented for the May 6, 1987 squall system. The mesoscale convective system exhibited evidence of significant midlevel detrainment in addition to transports to anvil heights. Chemical measurements of O3 and CO obtained in the convective environment are used to predict photochemical production within the troposphere and to corroborate the cloud model results.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 17015-17
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  • 89
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    Aerosol chemistry during the wet season in central Amazonia - The influence of long-range transport (1990)
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    Publication Date: 2011-08-19
    Description: The temporal variation in the concentration and chemistry of the atmospheric aerosol over central Amazonia, Brazil, during the 1987 wet season is discussed based on ground and aircraft collected data obtained during the NASA GTE ABLE 2B expedition conducted in April/May 1987. It is found that wet-season aerosol concentrations and composition are variable in contrast to the more uniform biogenic aerosol observed during the 1985 dry season; four distinct intervals of enhanced aerosol concentration coincided with short periods (3 to 5 d) of extensive rainfall. It is hypothesized that aerosol chemistry in Amazonia during the wet season is strongly influenced by long-range transport of soil dust, marine aerosol, and possibly biomass combustion products advected into the central Basin by large-scale tropospheric circulation, producing periodic pulses of material input to local boundary layer air. The resultant wet-season aerosol regime is dynamic, in contrast to the uniformity of natural biogenic aerosols during the dry season.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 16955-16
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  • 90
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    Zonal Navier-Stokes methodology for flow simulation about a complete aircraft (1990)
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 27; 583-590
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  • 91
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    Supercomputer applications in gas turbine flowfield simulation (1990)
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    Publication Date: 2011-08-19
    Description: The numerical simulation of the unsteady three-dimensional viscous flow in a gas turbine stage is considered. Results from a three-dimensional time-accurate Navier-Stokes simulation of rotor-stator interaction in an axial turbine stage are presented. The present study uses a fine grid in the spanwise direction to better resolve the complex three-dimensional flowfield, and complements earlier reported coarse-grid calculations. Several different features of the flowfield are analyzed and compared to earlier calculations and to experimental data whenever possible. Computer animation techniques are used to visualize various unsteady three-dimensional features of the flow. The results demonstrate the capabilities of current computing hardware in obtaining accurate simulations of unsteady flows in turbomachines.
    Keywords: AERODYNAMICS
    Type: International Journal of Supercomputer Applications (ISSN 0890-2720); 4; 81-95
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  • 92
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    An algorithm for retrieving water vapor profiles in clear and cloudy atmospheres from 183 GHz radiometric measurements - Simulation studies (1990)
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    Publication Date: 2011-08-19
    Description: The latent heat represented by atmospheric water vapor is extremely important to the energetics of the earth system. Future satellites (NOAA and DMSP) will carry microwave radiometers designed to measure the profile of water vapor globally. The problem of retrieving water vapor from the measurements is highly nonlinear even in clear atmospheres and the addition of clouds only makes it more so. In this paper, an algorithm with several novel features, which will retrieve water vapor profiles from microwave radiometric measurements even in the presence of clouds, is developed. Simulations with this algorithm show a vertical resolution on the order of 3 km and that clouds are well handled in many, but not all, circumstances. The most surprising result is that clouds can actually improve the vertical resolution of the retrieval.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Applied Meteorology (ISSN 0894-8763); 29; 508-515
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  • 93
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    Convective dynamics - Panel report (1990)
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    Publication Date: 2011-08-19
    Description: Aspects of highly organized forms of deep convection at midlatitudes are reviewed. Past emphasis in field work and cloud modeling has been directed toward severe weather as evidenced by research on tornadoes, hail, and strong surface winds. A number of specific issues concerning future thrusts, tactics, and techniques in convective dynamics are presented. These subjects include; convective modes and parameterization, global structure and scale interaction, convective energetics, transport studies, anvils and scale interaction, and scale selection. Also discussed are analysis workshops, four-dimensional data assimilation, matching models with observations, network Doppler analyses, mesoscale variability, and high-resolution/high-performance Doppler. It is also noted, that, classical surface measurements and soundings, flight-level research aircraft data, passive satellite data, and traditional photogrammetric studies are examples of datasets that require assimilation and integration.
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  • 94
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    Atmospheric water vapour over oceans from SSM/I measurements (1990)
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    Publication Date: 2011-08-19
    Description: A statistical retrieval technique is developed to derive the atmospheric water vapor column content from the Special Sensor Microwave/Imager (SSM/I) measurements. The radiometer signals are simulated by means of radiative-transfer calculations for a large set of atmospheric/oceanic situations. These simulated responses are subsequently summarized by multivariate analyses, giving water-vapor coefficients and error estimates. Radiative-transfer calculations show that the SSM/I microwave imager can detect atmospheric water vapor structures with an accuracy from 0.145 to 0.17 g/sq cm. The accuracy of the method is confirmed by globally distributed match-ups with radiosonde measurements.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: International Journal of Remote Sensing (ISSN 0143-1161); 11; 753-766
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  • 95
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    Effect of detailed surface geometry on riblet drag reduction performance (1990)
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    Publication Date: 2011-08-19
    Description: A comparison is made of the effect of small changes in v-groove geometry, for several riblet films applicable for drag reduction to commercial transport aircraft, whose nominal v-groove dimension is of the order of 0.002 inch. The films were tested in a water towing-tank facility. The results obtained indicate that small riblet peak geometry variations can result in a deterioration of riblet drag-reduction efficacy of as much as 40 percent, while interriblet valley curvature was found not to be critical to riblet performance.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 27; 572
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  • 96
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    High-resolution shock-capturing schemes for inviscid and viscous hypersonic flows (1990)
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    Publication Date: 2011-08-19
    Description: Hypersonic computations are presently conducted with an extension of a class of high-resolution implicit TVD algorithms suited to transonic multidimensional Euler and Navier-Stokes equations. These conservative shock-capturing schemes, which are spatially second- and third-order, may be first- and second-order accurate in time and suitable for either steady or unsteady calculations. Attention is given to the enhancement of hypersonic flows' convergence rate and stability; accuracy and efficiency is achieved by these means for very complex two-dimensional hypersonic viscous and inviscid shock interactions.
    Keywords: AERODYNAMICS
    Type: Journal of Computational Physics (ISSN 0021-9991); 88; 31-61
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  • 97
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    Aspects of the Kelvin wave response to episodic wind forcing (1990)
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    Publication Date: 2011-08-19
    Description: Episodes of westerly wind are an important aspect of surface stress variability in the western Pacific. During ENSO periods, the presence of such wind episodes comprises much of the LF relaxation of the trades over the central and western Pacific. This paper describes the oceanic Kelvin pulse response to a single idealized episode of westerly wind stress, using results from linear theory as well as from a 27-level general circulation model. When stratification typical of the western and eastern Pacific is used, the conservation of energy flux predicts a reduction of surface currents associated with the first baroclinic mode and an enhancement of surface currents associated with the second baroclinic mode. The idealized wind anomaly is also used to drive an ocean general circulation model. When the wind anomaly is weak, the model Kelvin response agrees with predictions of linear theory. For more realistic strong forcing there are three important deviations from linear theory: the amplitude of low baroclinic modes increases; the amplitude of higher baroclinic modes decreases; and the phase speed increases.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 7289-731
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  • 98
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    Aeroassisted Flight Experiment aerodynamic characteristics at flight conditions (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The success of NASA's Aeroassisted Flight Experiment project depends on the suitable placement of instrumentation on the vehicle surface and the ability of the vehicle to fly the maximum science payload. The initial aerodynamic data base was established using wind tunnel data and CFD analyses, where the influence of real-gas effects precluded the use of ground-facility data. More recently, a viscous thermochemical nonequilibrium flow analysis about the complete vehicle, including the wake, has updated the vehicle aerodynamic data base.
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 27; 684-686
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  • 99
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    Precise monitoring of global temperature trends from satellites (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Passive microwave radiometry from satellites provides more precise atmospheric temperature information than that obtained from the relatively sparse distribution of thermometers over the earth's surface. Accurate global atmospheric temperature estimates are needed for detection of possible greenhouse warming, evaluation of computer models of climate change, and for understanding important factors in the climate system. Analysis of the first 10 years (1979 to 1988) of satellite measurements of lower atmospheric temperature changes reveals a monthly precision of 0.01 C, large temperature variability on time scales from weeks to several years, but no obvious trend for the 10-year period. The warmest years, in descending order, were 1987, 1988, 1983, and 1980. The years 1984, 1985, and 1986 were the coolest.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Science (ISSN 0036-8075); 247; 1558-156
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  • 100
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    Hypersonic viscous shock-layer solutions over long slender bodies. II - Low Reynolds number flows (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 27; 185-193
    Format: text
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