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  • 1
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    Space debris impact experiment (S0001) (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The specific objectives of this experiment are to establish the population and size distribution of meteoroids in the mass range from 10 to the minus 10 power to 10 to the minus 4 power G, to establish the current population of man-made debris in the same mass range, and to obtain data on the physical properties (composition and density) of meteoroids.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Long Duration Exposure Facility (LDEF); p 136-137
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  • 2
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    Interplanetary dust experiment (A0201) (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The objective of this experiment is to study interplanetary dust, variously referred to as cosmic dust, cometary dust, zodiacial dust, or meteoric dust particles. Specific objectives are to obtain information regarding particle mass and velocity, and to undertake correlative analyses with other experiments, both on LDEF or near the time of the LDEF flight.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Long Duration Exposure Facility (LDEF); p 134-135
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  • 3
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    Attempt at dust debris collection with stacked detectors (A0138-2) (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The primary objective of this experiment is to investigate the feasibility of future missions of multilayer thin-film detectors acting as energy sorter to collect micrometeoroids, if not in their original shape, at least as fragments suitable for chemical analysis. It is expected that this kind of particle collector will help in solving one of the most puzzling topics in cosmic-dust studies: the mineralogical and chemical composition of the particles. This is a matter of great interest in the study of the origin and evolution of the solar system.
    Schlagwort(e): ASTROPHYSICS
    Materialart: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 124-126
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  • 4
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    Lightning research: A user's lament (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: As a user of devices and procedures for lightning protection, the author is asking the lightning research community for cookbook recipes to help him solve his problems. He is lamenting that realistic devices are scarce and that his mission does not allow him the time nor the wherewithal to bridge the gap between research and applications. A few case histories are presented. In return for their help he is offering researchers a key to lightning technology--the use of the Eastern Test Range and its extensive resources as a proving ground for their experiment in the lightning capital of the United States. A current example is given--a joint lightning characterization project to take place there. Typical resources are listed.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: NASA. Langley Research Center Intern. Aerospace and Ground Conf. on Lightning and Static Elec.; 6 p
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  • 5
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    Passive exposure of Earth radiation budget experiment components (A0147) (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: In-flight calibration for the solr and Earth flux channels was examined. Earth Radiation on Budget (ERB) channel components were exposed to the space environment and then retrieved and resubmitted to radiometric calibration after exposure. It is suggested that corrections may be applied to ERB results and information will be obtained to aid in the selection of components for future operational solar and Earth radiation budget experiments. To assure that these high accuracy devices are measuring real variations and are not responding to changes induced by the space environment, it is desirable to test such devices radiometrically after exposure to the best approximation of the orbital environment.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 167-169
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  • 6
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    Interstellar-gas experiment (A0038) (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The objectives of this experiment are to collect and isotopically analyze interstellar gas atoms around the orbit of the Earth for the purpose of obtaining new data relevant to understanding nucleosynthesis, and to study the dynamics of the interstellar wind inside the heliosphere and the isotopic composition of the interstellar medium outside the heliosphere. The experiment hardware will act as a set of simple cameras with high-purity copper-beryllium collecting foils serving as the film. The experiment housing will mount and thermally control the foils, establish the viewing angles and viewing direction, provide baffling to reject ambient neutral particles, provide a voltage grid to reject ionospheric charged particles, sequence collecting foils, control exposure times, and protect the foils from contamination during the deployment and retrieval of the LDEF. After being returned to Earth, the entrapped atoms can be analyzed by mass spectroscopy to determine the relative abundance of the different isotopes of helium and neon. An attempt will also be made to detect argon.
    Schlagwort(e): ASTROPHYSICS
    Materialart: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 98-100
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  • 7
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    Some aspects of understanding changes in the global carbon cycle (1984)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-19
    Beschreibung: The collective character of carbon exchanges between the atmosphere and other pools is partially revealed by comparing the record of CO2 concentration beginning in 1958 with estimates of the releases from fossil fuels during this period. In analyzing the secular increase in CO2 concentration induced by fossil fuel use, the atmosphere is generally treated as a single well-mixed reservoir; however, to study finer structure in the CO2 records, the influence of atmospheric circulation must be more carefully considered. The rate of carbon uptake by the oceans, the primary sink for fossil fuel CO2, is assessed more reliably than influences on the atmosphere due to interactions with other pools. Models of the global carbon cycle are being substantially refined while data that reflect the response of the cycle to fossil fuel use and other perturbations are being extended.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: JPL The interaction of Global Biochemical Cycles; p 55-84
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  • 8
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    A statistical correlation method for the retrieval of atmospheric moisture profiles by microwave radiometry (1984)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-18
    Beschreibung: A statistical correlation technique is applied to the retrieval of vertical moisture profiles under clear-sky conditions from down-looking radiometric measurements of atmospheric radiation at microwave wavelengths. For a given set of channels, the method selects the optimum radiometric channels for estimating water vapor at specific pressure levels between the surface and 300 mb. The water vapor mixing ratio at these pressure levels is then calculated from a linear combination of the selected channel brightness temperatures. To test its validity the algorithm was applied, in a numerical experiment, to fifty independent tropical radiosondes. The rms absolute deviation of the estimated moisture profiles from the actual profiles was comparable to that obtained using an iterative retrieval method reported earlier. The statistical method, however, requires several orders of magnitude less computer time than the iterative method; it is suitable for high speed processing of large amounts of data.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Journal of Climate and Applied Meteorology (ISSN 0733-3021); 23; 1110-111
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  • 9
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    High spatial resolution IR observations of young stellar objects - A possible disk surrounding HL Tauri (1984)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-18
    Beschreibung: High spatial resolution images of the T Tauri star HL Tau were obtained at 1.6 microns and 2.2 microns. The original images as well as maximum entropy image reconstructions reveal a circumstellar envelope structure, similar at both wavelenghts, and extended along P.A. = 112 deg; the 10 percent width of the structure is 1.9 sec (300 AU at 160 pc). The extended structure is interpreted as light scattered toward earth by dust in a disk surrounding this young stellar object. Polarization measurements made at 2.2 microns support this hypothesis. The total solid particle mass is, at minimum, 5 x 10 to the -7th solar mass.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 283; L57-L61
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  • 10
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    The overshoot region at the bottom of the solar convection zone (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The extent and thermal stratification of the region of convective overshoot underneath the convection zone of the sun are investigated. The phenomenon of convective overshoot in general is discussed, and some of the modal and model approaches to studying it are briefly reviewed. A detailed theoretical description of the motion of plumes in a stably stratified medium is given, leading to a 'derivation' of the plume equations from the hydrodynamic equations. Entrainment is discussed, and it is shown how the plume equations can be used to compute convective overshoot in the sun. The limitations of the plume model are addressed, arguing that a thin boundary layer must exist which separates convective and radiative regions. The results of numerical integrations of the plume equations, as applied to the region of convective overshoot underneath the solar convective zone, are discussed.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 282; 316-329
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  • 11
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    Problems in simulating the stratocumulus-topped boundary layer with a third-order closure model (1984)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-18
    Beschreibung: The Andre et al. (1976, 1978) third-order closure model, in which the time rate of change terms, the relaxation and rapid effects for pressure-related terms, and the clipping approximation are used along with the quasi-normal closure, is invoked in the study of turbulence in a cloudy layer that is radiatively cooled from above. A spurious oscillation whose greatest amplitude lies near the inversion is shown by analysis to arise from the mean gradient and buoyancy terms of the triple-moment equations. An attempt is made to damp the oscillation through the introduction of diffusion terms into the triple-moment equations. The results obtained are noted to be sensitive to the ad hoc eddy coefficient applied in the third-moment equations.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Journal of the Atmospheric Sciences (ISSN 0022-4928); 41; 1588-160
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  • 12
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    Very slow classical Cepheids - Theoretical models with periods longer than 50 days (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Systematics of the light curves of classical Cepheids with the longest known periods have been investigated with the help of full-amplitude models of pulsating stellar envelopes. For periods exceeding about 60 days, flat-topped light curves of the S Vul type are found to replace the smooth, asymmetric light curves characteristic of the slightly faster Cepheids. Predicted light and velocity amplitudes (although not the predicted radius amplitudes) agree well with observations. Variables with fluctuating light minima are observed to lie well off the mean period-luminosity relation, as are a few other (more stable?) variables with similarly long periods. The explanation for the long periods is probably low effective temperature rather than a low stellar mass. Because of the abnormal slowness of the classical Cepheids with periods longer than about 100 days, it is recommended that these variables not be used to calibrate the mean period-luminosity relation. Analogies between the slow classical Cepheids and the slow Population II Cepheids are drawn.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 281; 811-814
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  • 13
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    On the '3 kiloparsec arm' - Resonance excitation of linear and nonlinear waves by an oval distortion in the central region (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The mechanism responsible for the massive rapidly expanding Galactic feature known as the 3-kpc arm (Rougoor and Oort, 1960) is investigated theoretically in the framework of a density-wave model of the Galaxy. The arm is attributed to outgoing waves excited at the outer Lindblad resonance (OLR) of a small rotating oval distortion near the Galactic center. Linear and nonlinear models are developed, and it is shown that a density crest at 3.5 kpc with expansion velocity 53 km/s can be generated by a distortion turning at 118 km/s kpc with a 10-percent perturbation of the main gravitational field at the OLR (located at 3 kpc). The wave character of the nonlinear solution is found to be the same as that of the linear solution and to give good agreement with the observations in terms of expansion velocity, size, shape, and mass; only the observed asymmetry of the arm is not reproduced.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 281; 600-613
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  • 14
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    Superclustering and the large-scale structure of the Universe (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: A complete redshift survey of nearby rich galactic clusters is analyzed in terms of a spatial correlation function, the growth of supercluster, the presence of superclusters around the Bootes void and the discovery of a 300 Mpc void. Abell's (1958) statistical sampling of rich clusters is used for the study. Attention is given to the dependence of the correlation function on the richness of the system, with finding that chances are greater of finding rich neighbors closer together than poor neighbors. Samples of redshifts of 4 or less correlate well with clusters of redshift 5 or more. The size of intergalactic voids is proportional to the surrounding galactic excesses. Finally, the superclusters exist on scales of about 100 Mpc/h, which is larger than expected.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Advances in Space Research (ISSN 0273-1177); 3; 10-12
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  • 15
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    Ultraviolet spectral morphology of the O stars - The remarkable luminosity dependence of the Si IV stellar wind effect (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: An extensive survey of ultraviolet O type spectra, by means of high-resolution data from the International Ultraviolet Explorer archives, shows a strong correlation between both the photospheric and stellar wind features, and the optical spectral types. In particular, the stellar wind effect in the Si IV resonance doublet displays a strong luminosity dependence which has not been completely described before: there is no effect anywhere on the main sequence, but it develops gradually through the intermediate luminosity classes into a full P Cygni profile in the supergiants. This behavior is in sharp contrast to that of the C IV and N V, which have strong P Cygni profiles throughout most of the O type domain, including the main sequence. The Si IV effect simultaneously provides a sensitive classification criterion and poses an outstanding problem for detailed astrophysical interpretation. In addition, a new emission feature at 1574 A, possibly due to N III or to N IV forbidden line, is reported.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 280; L27-L30
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  • 16
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    Beam-return current systems in solar flares (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: It is demonstrated that the common assumption made in solar flare beam transport theory that the beam-accompanied return current is purely electrostatically driven is incorrect, and that the return current is both electrostatically and inductively driven, in accordance with Lenz's law, with the inductive effects dominating for times greater than a few plasma periods. In addition, it is shown that a beam can only exist in a solar plasma for a finite time which is much smaller than the inductive return current dissipation time. The importance of accounting for the role of the acceleration mechanism in forming the beam is discussed. In addition, the role of return current driven anomalous resistivity and its subsequent anomalous Joule heating during the flare process is elucidated.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 280; 448-456
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  • 17
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    Radiative and reconnection instabilities - Filaments and flares (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The way in which the initial development of solar filament radiative cooling and the magnetic reconnection of a solar flare can occur in the center of a field-shear layer is demonstrated. Since the present treatment unites these two mechanisms, it indicates the common as well as the disparate features they possess. Unstable radiation serves to increase the Coulomb resistivity at the X-point, so that the reconnection is not self-quenching. The surprising dominance of the magnetic component of the perturbation in the midwavelength range indicates the need to examine the nonlinear saturation of the energy transport of the radiative mode, taking the accompanying magnetic reconnection and potential-energy release into account, for comparison with observations of filaments as well as for clues to the character of the preflare state.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 280; 391-398
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  • 18
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    A second chance for Solar Max (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Using NASA's Tracking and Data Relay Satellite as a communications link, astronomers are able to receive scans from the Solar Maximum Mission (SMM) satellite immediately and regularly at the Goddard Space Flight Center. This major operational improvement permits the examination of SMM imagery and spectra as they arrive, as well as the formulation of future observational sequences on the basis of the solar activity in progress. Attention is given to aspects of the sun that change in the course of the 11-year sunspot cycle's movement from maximum to minimum. Proof has been obtained by means of SMM for the near-simultaneity of X-ray and UV bursts at flare onset.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Sky and Telescope (ISSN 0037-6604); 67; 498-500
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  • 19
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    Do bipolar magnetic regions exist on the surfaces of early-type stars? (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The observations of relatively narrow absorption components of the UV resonance lines in the spectra of early-type stars are reviewed, and some new observational data are presented for Rho Leo (B1 Ib). It is shown that the discrete components which are seen in the UV resonance lines of early-type stars are a result of ejection from local spots above the photospheres of hot stars. It is suggested that localized ejection is caused by magnetic flux lines associated with a bipolar magnetic region on the surface of the star.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 280; 712-728
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  • 20
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    Models of the hard X-ray spectrum of AM Herculis and implications for the accretion rate (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Phenomenological fits to the hard X-ray spectrum of AM Hercules have failed to explain the high equivalent width (0.8 + or - 0.1 keV) of Fe K-alpha emission. The scattering and fluorescent line production in a cold or partially ionized accretion column of hard X-rays emitted at the base are investigated using the Monte Carlo method. It is shown that the Fe emission equivalent width observed in the spectrum of AM Her can be explained without resorting to an overabundance of Fe in the accreting material. For sufficient optical depth across the accretion column, equivalent widths of K-alpha emission even larger than the observed values can be obtained. The accretion rate and gravitational power can be deduced from the optical depth across the column, if the column size is known, and, together with the observed hard X-ray and polarized light luminosities, imply a lower limit for the luminosity in the UV to soft X-ray range, for which the observations give model-dependent values.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 280; 734-743
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  • 21
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    Disappearance and disintegration of comets (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The present investigation has the objective to provide a summary of the existing evidence on the disappearance of comets and to draw conclusions regarding the physical processes involved in the disappearance. Information concerning the classification of evidence and the causes of apparent disappearance of comets is presented in a table. Attention is given to the dissipating comets, the headless sungrazing comet 1887 I, and the physical behavior of the dissipating comets and the related phenomena. It is found that all comets confined to the planetary region of the solar system decay on astronomically short time scales. However, only some of them appear to perish catastrophically. Some of the observed phenomena could be successfully interpreted. But little insight has been obtained into the character of the processes which the dissipating comets experience.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Icarus (ISSN 0019-1035); 58; 81-100
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  • 22
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    X-ray spectral signatures of accreting black holes (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The X-ray properties of the binary black hole candidates include distinctive bimodal spectral behavior where the X-ray spectra switch between being very soft (alpha greater than 3) and hard (alpha about 0.7). It is pointed out that this spectral transition occurs at about 1 percent L(edd) (for accretion onto a 10 solar masses black hole), and that this corresponds to the luminosity where an optically thick electron-positron pair plasma will form. Active galactic nuclei (AGN) are often considered to be accreting black holes. An X-ray spectral similarity between the above binary sources and both the Seyfert I and BL Lac classes of AGN is demonstrated. As many of these objects radiate most of their luminosity as X-rays, such a similarity may be expected if the underlying mechanisms are similar.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astronomy and Astrophysics (ISSN 0004-6361); 133; 2, Ap
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  • 23
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    Lightning activity and severe storm structure (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Space-time mapping of VHF sources from four severe storms on June 19, 1980 reveals that lightning processes for cloud-to-ground (CG) and large intracloud (IC) flashes are confined to an altitude below about 10 km and closely associated with the central regions of high reflectivity. Another class of IC flashes produces a splattering of sources within the storms' main electrically active volumes and also within the large divergent wind canopy aloft. There is no apparent temporal association between the small high altitude IC flashes that occur almost continuously and the large IC and CG flashes that occur sporadically in the lower portions of storms.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Geophysical Research Letters (ISSN 0094-8276); 11; 545-548
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  • 24
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    Spectral analysis of magnetohydrodynamic fluctuations near interplanetary shocks (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Preliminary results of an investigation of magnetic fluctuations seen upstream of two interplanetary shocks are presented. The spectral analysis includes calculation of the normalized reduced magnetic helicity spectrum, the normalized reduced cross-helicity spectrum, and the Alfven ratio as discussed by Matthaeus and Goldstein (1982). Minimum variance methods are used to compute wave polarization as a function of frequency. The Taylor 'frozen in flow' hypothesis is assumed to convert frequencies to wave vectors. Some of the basic properties of the waves, including the probable mode of propagation in association with both quasi-parallel forward and reverse shocks, are described. A comparison with previous results on the generation of waves at interplanetary and planetary shocks is presented.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 89; 3762-377
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  • 25
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    A variational formulation for time-dependent climate models (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: A variational principle for time dependent diffusion problems is presented and is demonstrated by applying it to simple seasonal climate models. Two cases are treated. The first, a North-Coakley-type model with constant properties, is used as a tutorial example for the application of the technique. For the second case, heat capacity and thermal conductivity are considered to be latitude dependent in order to treat the effects of land/ocean distribution on the seasonal temperature distribution over the earth. The variational equations are derived and approximate analytical solutions are developed which delineate the influences of the physical asymmetries of the hemispheres in producing an asymmetric annual cycle.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 89; 2601-260
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  • 26
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    Analogs in the wintertime 500 mb height field (1984)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-18
    Beschreibung: Lorenz (1969) has considered the possibility that an atmospheric circulation pattern might recur, taking into account the definition of a pair of analogous flows or 'analogs'. The present investigation is concerned with a search of time series of Northern Hemisphere wintertime geopotential heights for possible analogs. Attention is given to data and analysis procedure, analog quality, and error growth rates. The obtained results imply that the found analogs are not a useful tool for forecasting the evolution of the midlatitude flow on time scales of several days. It is pointed out, however, that the negative results should not be extended to other applications of analog forecasting.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Journal of the Atmospheric Sciences (ISSN 0022-4928); 41; 177-189
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  • 27
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    HEAO 3 observations of the Crab pulsar (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The Crab pulsar (PSR 0531+21) is the only pulsar which has been observed throughout almost the entire electromagnetic spectrum from 0.5 keV to over 2000 GeV. In general, the emission from the Crab nebula and its pulsar has been remarkably constant in time (except for the pulsations). However, several recent observations, especially of gamma-ray line emission, indicate possible time variations. The present investigation is concerned with the data obtained with the HEAO C-1 experiment. The data have been studied with the hope of finding information regarding a number of questions, taking into account the existence of line emission from the pulsar, the variation of the shape of the light curve with time, and the spectral variations as a function of pulsar phase. The spectrum of the total phase-averaged pulsed emission is found to be consistent with a single power-law spectrum from 50 keV to 10 MeV.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 278; 784-790
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  • 28
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    X-ray observations of X Persei (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The HEAO 2 Einstein Observatory was used to confirm the identification of 4U 0352 + 30 with X Per. The HEAO 2 data were analyzed in order to determine an additional point in the pulse period history of the X-ray source and to search for short binary periods. In addition, a majority of the historical X-ray observations was reanalyzed and more refined values for the pulse period as a function of time were obtained. The period history possess significant scatter, but no evidence for a measurable long-term spin-up trend is found, and hence a lower limit to the spin-up time scale is set. This lower limit is consistent with the presence of a neutron star, but it does not rule out a degenerate dwarf. The period history was also searched for evidence of binary motion, and upper limits to a(x) sin i were obtained.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 278; 711-715
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  • 29
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    Variable ultraviolet emission in SY Muscae (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The results of continued IUE monitoring of the symbiotic variable SY Muscae, following an earlier report of a radical enhancement in UV emission from the star, are reported. Over the course of one year, the prominent emission lines of N V, O V, C IV, and He II appear to be gradually decreasing in absolute intensity. This appears to coincide with a steady decline in electron density in the emission line forming region. The data are consistent with a sudden ejection event in which material expelled from the surface of a hot subdwarf has exposed the underlying UV continuum of the star. A number of strong emission lines that are photoexcited by the intense radiation field of the secondary also exhibit broad pedestal emission that suggests turbulent velocities of about 150-300 km/s in an expanding shell or possibly in an accretion disk.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 207; 575-583
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  • 30
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    Large scale temporal and radial gradients in the IMF - Helios 1, 2, ISEE-3, and Pioneer 10, 11 (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Recent investigations using measurements at 1 AU have discovered three types of long term variation in the interplanetary magnetic field: solar minimum decreases, solar maximum enhancements, and small decreases around solar reversal. In this study the 1972-1982 Helios 1, 2, ISEE-3, and Pioneer 10, 11 observations between 0.3 and 12 AU are examined to further investigate these changes. It was found that all three IMF solar cycle effects are also present in the Helios and Pioneer measurements, confirming that these variations occur throughout the low latitude heliosphere. In addition, the comparison of measurements by identical magnetometers on ISEE-3, Pioneer 10 and Pioneer 11 has revealed a more rapid decrease in IMF intensity than predicted by classical Parker theory. Causes and ramifications of both the long term variations and steeper-than-expected radial gradients in the interplanetary magnetic field are discussed.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Geophysical Research Letters (ISSN 0094-8276); 11; 279-282
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  • 31
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    The remarkable ultraviolet spectrum of the planetary nebula Abell 30 (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Abell 30 has been identified as a planetary nebula in which the nucleus has experienced a final helium shell flash after ejection of the original, outer envelope. Around the central star of the nebula, four knots of material are observed. In view of the importance of the chemical composition of the ejected material for studies of advanced stages of stellar evolution, clarification of the physical conditions in the knots is vital. Data obtained of Abell 30 with the aid of the International Ultraviolet Explorer (IUE) satellite are discussed along with aspects of extinction, the He II flux, ionic abundances, the C II lambda 4267 line, questions regarding the existence of a carbon-rich core in the knot, the heating of the nebular gas, the central star, and heating by suprathermal particles from the stellar wind. The UV spectrum of the inner nebulosity of Abell 30 indicates that an extraordinary amount of energy is being deposited in the gas.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 277; 716-724
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  • 32
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    Transient behavior of a flare-associated solar wind. I - Gas dynamics in a radial open field region (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: A numerical investigation is conducted into the way in which a solar wind model initially satisfying both steady state and energy balance conditions is disturbed and deformed, under the assumption of heating that correspoonds to the energy release of solar flares of an importance value of approximately 1 which occur in radial open field regions. Flare-associated solar wind transient behavior is modeled for 1-8 solar radii. The coronal temperature around the heat source region rises, and a large thermal conductive flux flows inward to the chromosphere and outward to interplanetary space along field lines. The speed of the front of expanding chromospheric material generated by the impingement of the conduction front on the upper chromosphere exceeds the local sound velocity in a few minutes and eventually exceeds 100 million cm/sec.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 277; 379-391
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  • 33
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    Highlights of the Symposium on the Multiple-Parameter Radar Measurements of Precipitation - Personal reflections. (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Radio Science (ISSN 0048-6604); 19; 238-242
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  • 34
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    A study of extreme carbon stars. I - Silicon carbide emission features (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: 10-micron spectra of many extreme carbon stars reveal a prominent emission feature near 11 microns. This is compared with laboratory spectra of SiC grains. Two distinct types of features are found, perhaps indicative of different mechanisms of grain formation in different stars. Estimates are made of probable column densities and total masses of SiC in the circumstellar shells.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 206; 137-147
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  • 35
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    MHD processes in the outer heliosphere (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The magnetic field measurements from Voyager and the magnetohydrodynamic (MHD) processes in the outer heliosphere are reviewed. A bibliography of the experimental and theoretical work concerning magnetic fields and plasmas observed in the outer heliosphere is given. Emphasis in this review is on basic concepts and dynamical processes involving the magnetic field. The theory that serves to explain and unify the interplanetary magnetic field and plasma observations is magnetohydrodynamics. Basic physical processes and observations that relate directly to solutions of the MHD equations are emphasized, but obtaining solutions of this complex system of equations involves various assumptions and approximations. The spatial and temporal complexity of the outer heliosphere and some approaches for dealing with this complexity are discussed.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Space Science Reviews (ISSN 0038-6308); 39; 255-316
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  • 36
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    Cosmogony as an extrapolation of magnetospheric research (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: A theory of the origin and evolution of the Solar System which considered electromagnetic forces and plasma effects is revised in light of information supplied by space research. In situ measurements in the magnetospheres and solar wind can be extrapolated outwards in space, to interstellar clouds, and backwards in time, to the formation of the solar system. The first extrapolation leads to a revision of cloud properties essential for the early phases in the formation of stars and solar nebulae. The latter extrapolation facilitates analysis of the cosmogonic processes by extrapolation of magnetospheric phenomena. Pioneer-Voyager observations of the Saturnian rings indicate that essential parts of their structure are fossils from cosmogonic times. By using detailed information from these space missions, it is possible to reconstruct events 4 to 5 billion years ago with an accuracy of a few percent.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Space Science Reviews (ISSN 0038-6308); 39; 65-90
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  • 37
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    Solar-flare neutrons and gamma-rays (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The numbers and spectra of the accelerated protons and nuclei that produce the neutrons and gamma-rays observed in solar flares are derived, and the results are compared with interplanetary observations of flare protons. The two most widely studied flare acceleration mechanisms, stochastic and diffusive shock acceleration, are discussed, and the arguments favoring the thick-target interaction model for neutron and gamma-ray production at the sun are briefly reviewed. The pertinent results of the theory of neutron and gamma-ray production are presented. The number and spectrum of the accelerated particles are derived from observations of nuclear deexcitation lines and the 2.223 MeV line from several flares. The June 21, 1980 and June 3, 1982 flares, from which a wealth of neutron, gamma-ray and energetic-particle data has recently become available, are discussed.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Advances in Space Research (ISSN 0273-1177); 4; 7, 19
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  • 38
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    Recurrent mass ejections observed in H-alpha and CIV (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Time sequences of recurrent mass ejections have been observed during a coordinated SMY program (Sept. 1, 1980 - Sept. 23, 1980 - Oct. 2, 1980). Comparison of the temporal evolution of H-alpha and CIV brightnesses shows a weak phase lag between H-alpha and CIV maxima, in the case of homologous flares, with CIV brightness maxima preceding H-alpha maxima. The analysis of the variation of the ejection velocities is expected to lead to the determination of an energy balance. Such recurrent ejections could be due to periodic energy storage and periodic reorganization of magnetic field as envisaged to occur for flares, but at lower energy levels.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Advances in Space Research (ISSN 0273-1177); 4; 7, 19
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  • 39
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    The small ice cap instability in diffusive climate models (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Simple climate models which invoke diffusive heat transport and ice cap albedo feedback have equilibrium solutions with no stable ice cap smaller than a radius of about 20 deg on a great circle. Attention is presently given to a solution of this phenomenon which is physically appealing. The ice-free solution has a thermal minimum, and if the minimum temperature is just above the critical value for ice formation, then the artificial addition of a patch of ice leads to a widespread depression of the temperature below the critical freezing temperature. A second stable solution will then exist whose spatial extent is determined by the range of the influence function of a point sink of heat, due to the albedo shift in the patch.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Journal of the Atmospheric Sciences (ISSN 0022-4928); 41; 3390-339
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  • 40
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    Comments on 'Comparative diagnostic case study of east coast secondary cyclogenesis under weak versus strong synoptic-scale forcing' (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: A comment is presented on a recent paper by Pagnotti and Bosart (1984) which contrasted different forcing mechanisms for weak and strong cyclones along the east coast of the U.S., and Bosart replies. The comment argues that the paper did not give a clear definition of 'weak' upper-level forcing and did not provide sufficient evidence to support its claim that the return branch of transverse circulations may be coupled to the middle as opposed to the lower troposphere.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Monthly Weather Review (ISSN 0027-0644); 112; 2540
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  • 41
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    A case for submergence of magnetic flux in a solar active region (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: In NOAA Active Region 2372 (April 1980), 4 x 10 to the 20th maxwells of magnetic flux concentrated in an area 30 arcsec across disappeared overnight. Vector magnetograms show that all components of the magnetic field weakened together. If the field had weakened through diffusion or fluid flow, 90 percent of the original flux would still have been detected by the magnetograph within a suitably enlarged area. In fact there was a threefold decrease in detected flux. Evidently, magnetic field was removed from the photosphere. Since the disappearing flux was located in a region of low magnetic shear and low activity in H-alpha and Ly-alpha, it is unlikely that the field dissipated through reconnection. It is argued that the most likely possibility is that flux submerged. The observations suggest that even during the growth phase of active regions, submergence is a strong process comparable in magnitude to emergence.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 287; 404-411
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  • 42
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    Detailed studies of the dynamics and energetics of coronal bullets (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Coronal bullets are small ejecta of cool, dense plasma observed to accelerate through the solar atmosphere from 20 to 450 km/s. The NRL Dynamic Flux Tube Model has been used to simulate the evolving physical properties of these dynamic events. The present calculations utilize an adaptive-gridding technique to resolve the fine structure within and around the bullets. In this work, an identification was made of a component of shocked plasma which piles up ahead of the bullet and eventually dominates both the dynamics and heating of the original bullet mass. The observational consequences of this shocked component are discussed in terms of the available HRTS EUV data, and suggestions are made for optimizing future observations of this phenomenon. An investigation has also been conducted of the structure of the bullet material visible in EUV spectral lines and the observable characteristics of the EUV-emitting plasma. Finally, the most likely mechanisms for accelerating the bullets, as well as favorable sites of origin are evaluated.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 287; 396-403
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  • 43
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    A numerical simulation of barotropic instability. II Wave-wave interaction (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: A fully nonlinear numerical model of the point jet barotropic instability is used to test and confirm the hypothesis that the magnitude of the wave vorticity does not exceed the magnitude of the initial shear. This result arises directly from the local conservation of vorticity following a parcel and the fact that unstable waves are principally confined to the region where the zonal mean vorticity can be smoothed by the wave so as to eliminate the instability. Comparisons are made between fully nonlinear and quasi-linear models of the point jet instability and their tracer transport properties. Differences become particularly evident after wave saturation. The most important effect neglected by the wave-mean flow model appears to be the advection of wave vorticity by the most unstable mode. However, as equilibration of the instability proceeds, the globally averaged properties of both models are found to be similar.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Journal of the Atmospheric Sciences (ISSN 0022-4928); 41; 2869-288
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  • 44
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    Thermal bifurcation in the upper photosphere inferred from heterodyne spectroscopy of OH rotational lines (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Low-noise (S/N greater than 100), high spectral resolution observations of two pure rotation transitions of OH from the solar photosphere are used to make inferences concerning the thermal structure and inhomogeneity of the upper photosphere. It is found that the v = O R22(24.5)e line strengthens at the solar limb, in contradiction to the predictions of current one-dimensional photospheric models. The results for this line support a two-dimensional model in which horizontal thermal fluctuations in the upper photosphere are of the order plus or minus 800 K. This thermal bifurcation may be maintained by the presence of magnetic flux tubes and may be related to the solar limb extensions observed in the 30-200-micron region.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Solar Physics (ISSN 0038-0938); 94; 57-74
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  • 45
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    Abundances in galactic H II regions. III - G25.4-0.2, G45.5+0.06, M8, S159, and DR 22 (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Measurements of the ARII (6.99 microns), ArIII (8.99 microns), NeI (12.81 microns), SIII (18.71 microns), and SIV (10.51 microns) lines are presented for five compact HII regions along with continuum spectroscopy. From these data and radio data, lower limits to the elemental abundances of Ar, S, and Ne were deduced. The complex G25.4-0.2 is only 5.5 kpc from the galactic center, and is considerably overabundant in all these elements. Complex G45.5+0.06 is at seven kpc from the galactic center, and appears to be approximately consistent with solar abundance. The complex S159 in the Perseus Arm, at 12 kpc from the galactic center, has solar abundance, while M8 in the solar neighborhood may be somewhat overabundant in Ar and Ne. Complex DR 22, at 10 kpc from the galactic center in the Cygnus Arm, is overabundant in Ar. A summary of results from a series of papers on abundances is given.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 285; 174-180
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  • 46
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    Intense X-ray flares from active stellar systems - EV Lacertae and HD 8357 (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The HEAO A-1 Sky Survey Experiment included X-ray data used to define light curves for the flare star EV Lac and for X-ray flares observed in the binary system HD 8357. The data were taken during flare events and were detailed enough to calculate the flare rates and flaring luminosities. The peak luminosities during flares were several times the luminosities in normal X-ray flares emitted by the objects. Peak luminosities reached 30-50 times the normal variations and were associated with an order of magnitude increase in energy output. EV Lac was sufficiently active to be recommended for inclusion in future X-ray monitoring programs.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 284; 270-277
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  • 47
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    Regularized Monte-Carlo calculations of the optical polarization induced by scattering in X-ray binaries (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The results of regularized Monte Carlo calculations of the optical polarization Stokes parameters expected as a result of scattering from gas streams or accretion wakes in close binary systems whose properties resemble those of X-ray binaries are presented. The physical processes occurring in the system are represented by a model which follows a selected sample of individual photon paths from each emitting element on the surface of the primary to the photon's detection at earth. The result represents the variations in the intensity from each individual emitting element caused by the effects of limb darkening, gravity darkening, and variation in the projected area of the emitting element as seen from the scattering element.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astronomy and Astrophysics (ISSN 0004-6361); 138; 1, Se
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  • 48
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    Some aspects of the interannual variation of mean monthly sea level pressure on the Southern Hemisphere (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: We calculate the seasonal changes that are largely associated with the half-yearly wave, autocorrelation functions, and the mean planetary waves in the monthly mean sea level pressure from two data sources. One covers the period from 1951 to 1958 (from the South African Weather Bureau) and the other the period from 1972 to 1980 (from the Australian Bureau of Meteorology). Thirty years of data from stations over the southern hemisphere are used to assess the reliability of the differences between the two periods that the grid-point data show. These differences are especially large over the Atlantic Ocean and the Pacific Ocean. The station data confirm the changes between the two periods and thus the observed differences in the mean waves, which are especially large for wave number 3.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 89; 9541-954
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  • 49
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    Precession model for the nucleus of periodic Comet Kopff (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The existing data base on certain characteristics of the periodic Comet Kopff, a candidate for a NASA rendezvous mission in the 1990s, is summarized. The comet was discovered in 1906. The data are used to calculate limits to the nuclear mass (0.7-1.5 x 10 to the 16th g), equatorial radius (1.26-1.64 km), and a geometric albedo of 0.08. An equatorial rotation velocity of 8.1-10.7 hr is projected. The estimates are highly dependent on the present photometric data, which in turn depend on the insolation rate, which if different than assumed could mean that all parameters would be revised upward significantly.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astronomical Journal (ISSN 0004-6256); 89; 1573-158
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  • 50
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    The H flux peak and the hydrogen abundance in N type carbon stars (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: For galactic N and late R type irregularly variable carbon stars, a comparison is made of airborne infrared spectrophotometry to spectral flux distributions derived from model atmospheres. Although the agreement is good in several respects, the H(-) emission peak at 1.6 microns, so prominent in the models, is significantly weakened in the stellar spectrophotometry. It seems unlikely that molecular bands in the stars can completely obliterate this peak. A plausible explanation is that hydrogen is deficient in these stars, most probably from an episode of mass loss. The resultant cold shells surrounding these stars should be amenable to observation by IRAS, or other far-infrared observatories.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 284; L39-L42
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  • 51
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    An X-ray survey of variable radio bright quasars (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: A sample consisting primarily of radio bright quasars was observed in X-rays with the Einstein Observatory for times ranging from 1500 to 5000 seconds. Detected sources had luminosities ranging from 0.2 to 41.0 x 10 to the 45th power ergs/sec in the 0.5 to 4.5 keV band. Three of the fourteen objects which were reobserved showed flux increases greater than a factor of two on a time scale greater than six months. No variability was detected during the individual observations. The optical and X-ray luminosities are correlated, which suggests a common origin. However, the relationship (L sub x is approximately L sub op to the (.89 + or - .15) found for historic radio variables may be significantly different than that reported for other radio bright sources. Some of the observed X-ray fluxes were substantially below the predicted self-Compton flux, assuming incoherent synchrotron emission and using VLBI results to constrain the size of the emission region, which suggests relativistic expansion in these sources. Normal CIV emission in two of the sources with an overpredicted Compton component suggests that although they, like BL Lac objects, have highly relativistic material apparently moving at small angle to the line of sight, they have a smaller fraction of the continuum component in the beam.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 284; 491-496
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    GASP cloud encounter statistics - Implications for laminar flow control flight (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The cloud observation archive from the NASA Global Atmospheric Sampling Program (GASP) is analyzed in order to derive the probability of cloud encounter at altitudes normally flown by commercial airliners, for application to a determination of the feasability of Laminar Flow Control (LFC) on long-range routes. The probability of cloud encounter is found to vary significantly with season. Several meteorological circulation features are apparent in the latitudinal distribution of cloud cover. The cloud encounter data are shown to be consistent with the classical midlatitude cyclone model with more clouds encountered in highs than in lows. Aircraft measurements of route-averaged time-in-clouds fit a gamma probability distribution model which is applied to estimate the probability of extended cloud encounter, and the associated loss of LFC effectiveness along seven high-density routes. The probability is demonstrated to be low.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Journal of Aircraft (ISSN 0021-8669); 21; 851-857
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    Some properties of the filamentary nebula at 1723 - 46 (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: High resolution spectra of the interstellar NaI D2 absorption line have been obtained for seven B-type stars aligned with an extensive filamentary nebula. Very fine filaments have now been found on a high contrast print of a deep H-alpha and forbidden N II plate, making identification as a fossilized remnant probable but uncertain. The inferred age is about 20,000 yr, the distance less than 200 pc, the diameter less than 17.5 pec, but the initial energy is only about 2 x 10 to the 47th erg.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 210; 693-699
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  • 54
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    Solar irradiance changes caused by g-modes and large scale convection (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Solar irradiance measurements from the ACRIM experiment show a clear response to the rotation periods of g-mode oscillations (l = 1, 2, and 3) and their first harmonics. Peaks in the ACRIM spectrum at 16.6, 18.3, 20.7, 36.5, and about 71 days all lie within about 1 percent of periods arising from g-mode rotation. This means that the g-modes are a fundamental cause of irradiance fluctuations. On time scales of months and less they modulate the irradiance by means of transient flows of global scale which they stimulate in the sun's convective envelope. Dimensional arguments indicate that the flows carry up heat at an average rate of about 0.001 solar luminosities, which is not in conflict with observed changes in the irradiance. Five additional tests for g-modes and large-scale convection are given. An instability is described which undermines diffusion models of sunspot energy storage.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Solar Physics (ISSN 0038-0938); 93; 1-13
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    Vertical temperature sounding of the atmosphere (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Attention is given to physical principles that affect the determination of atmospheric temperature profiles from observations of outgoing IR and microwave radiation. Simultaneous analysis of IR and microwave observations enhances observations in each spectral region. While IR soundings have higher sensitivity to lower tropospheric temperatures, ground temperatures, and sea surface temperatures, microwave observations are not only more suited to stratospheric sounding but are sensitive to snow and ice cover. They significantly aid correction of IR observations for cloud effects. Because effective cloud parameters and snow and ice cover can be inferred from the observations, 'temperature sounders' also yield data for a number of important climatic parameters.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
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  • 56
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    Lagrangian least-squares prediction of solar flux (F-bar 10.7) (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The result of a study on the application of an improved statistical prediction method for estimating the intermediate-term (months) and long-term (years) behavior of solar flux is discussed. The study indicates that better predictions, in a chi square sense, are possible by selecting sets of the solar flux data such that each set (cycle) starts and ends at the maxima (or minima) for the data base and initialization point of the procedure. Then one applies a Lagrangian least-squares statistical technique. Evidence is also presented to support the existence of an aperiodic variation in the periods as well as the amplitudes.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 89; 11-16
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  • 57
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    Grain destruction in interstellar shocks (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: The destruction of interstellar grains by nonthermal sputtering, thermal sputtering, and grain-grain collisions is discussed. It is concluded that large grains are easily destroyed by shocks in the interstellar medium, but that small grains are much more persistent. Since the MRN model has many more small grains than large ones, this means that the total number of grains is not significantly reduced even when half or more of the grain material is returned to the gas phase. Thus, the small grains are always available as condensation cores for mantle formation or redepletion of refractory grain materials.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Royal Observatory Lab. and Observational Infrared Spectra of Interstellar Dust; p 26-32
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  • 58
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    Application of a global solar wind/planetary obstacle interaction computational model: Earth, Venus, Mars, Jupiter and Saturn studies (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: This work relates to a series of collaborative investigations involving the application of a computational model for the determination of the detailed plasma and magnetic field properties associated with the global interaction of the solar wind with various planetary obstacles throughout the solar system. The theoretical method is based on an established single fluid, steady, dissipationless, magnetohydrodynamic continuum model, and is appropriate for the calculation of supersonic, super-Alfvenic solar wind flow past planetary obstacles. The investigations undertaken relate to studies of various solar wind interaction phenomena with Venus, Earth, Jupiter, and Saturn.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Appl. of a Global Solar Wind/Planetary Obstacle Interaction Computational Model 11p (SEE N84-26509 16-88)
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  • 59
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    Role of soil moisture in maintaining droughts (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: The influence of soil moisture on the persistence of an ongoing drought was investigated. The case study of drought of the summer of 1980 was selected. The difference in the simulation of two identical twin runs: one with the climatological normal soil moisture and the other with anomalous soil moisture for drought conditions, were examined on the mean monthly circulation. It is found that a reduction in soil moisture did produce a corresponding reduction in precipitation. The pattern of the rainfall anomaly however, was not identical to the soil moisture (evapotranspiration) anomaly but had a good resemblance with observations.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Res. Rev., 1983; p 335-340
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    The sensitivity of a general circulation model to Saharan dust heating (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: During the Northern summer, sporadic outbreaks of wind borne Saharan dust are carried out over the Atlantic by the tropical easterlies. Optical depths due to the dust can reach 3 near the African coast, and the dust cloud can be detected as far west as the Caribbean Sea (Carlson, 1979). In order to obtain insight into the possible effects of Saharan dust on the weather and climate of North Africa and the tropical Atlantic Ocean, simulation experiments have been performed with the Climate Model of the Goddard Laboratory for Atmospheric Sciences. The most recent version of the model is described by Randall (1982). The model produces realistic simulations of many aspects of the observed climate and its seasonal variation.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Res. Rev., 1983; p 3323-328
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  • 61
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    Climate sensitivity with a seasonal cycle energy balance model (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: The sensitivity of climate which may have a local maximum as the ice cap passes through a midlatitude region where the atmosphere's transport efficiency varies strongly with latitude is examined. This behavior, found in a two level primitive equations climate model forced with annual mean insolation, was reproduced in an energy balance model (EBM) by making the diffusion coefficient a function of latitude. The two level seasonally varying EBM was applied and the global mean surface temperature vs. solar constant for this model are shown and two regions of enhanced sensitivity appear. The snowcover distributions around the year for three cases are shown.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Res. Rev., 1983; p 227-230
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  • 62
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    On the role of the transient eddies in maintaining the seasonal mean circulation (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: The role of transient eddies in maintaining the observed local seasonal mean atmospheric circulation was investigated by examining the time-averaged momentum balances and omega equation, using seasonal statistics calculated from daily operational analyses by the European Centre for Medium Range Weather Forecasts. While both the Northern and Southern Hemispheres and several seasons were studied, emphasis was placed upon the Northern Hemisphere during December 1981-February 1982. The results showed that transient eddies played a secondary role in the seasonal mean zonal momentum budget and in the forcing of seasonal mean vertical and a geostrophic motion.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Res. Rev., 1983; p 205-208
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    Teleconnection patterns in the Southern Hemisphere (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: Contemporaneous correlations between geopotential heights on a given pressure surface at widely separated points on Earth, commonly referred to as teleconnections, are calculated from monthly mean sea level pressure and 500 mb geopotential height analyses for the Southern Hemisphere for five-month winter and summer seasons. During summer (November-March), anomalies over the three continents occur out of phase with anomalies over the subtropical oceans and in a wavenumber 3 pattern over the Southern Ocean near 55 deg S. The subtropical part of the pattern appears largely associated with the interannual variation of the seasonal cycle and annual mean. In winter (May-September) 500 mb geopotential heights over Africa exhibit positive correlations with heights over South America and the central South Pacific near New Zealand and negative correlations with height over the Southern Ocean. A striking wavenumber three pattern is apparent which shows the correlation of 500 mb geopotential height anomalies with 500 mb anomalies at 50 deg S, 95 deg E during winter. The strong positive correlations between 50 deg S, 95 E and 58 deg S, 150 deg W and 38 deg S, 15 deg W contrast with negative correlations over Antarctica and in low latitudes. Time variations in a similar pattern in sea level pressure are in phase with variations in the 500 mb pattern, suggesting an equivalent barotropic structure.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Res. Rev., 1983; p 193-195
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    Localized blocking accounted for by slow variations of the zonal driving (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: The incorporation of observed zonal topography in a barotropic nonlinear channel model is discussed. The model is then extended to explain the regional features of blocking by employing a two scale method to allow small slow variations of the momentum (zonal) driving.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Res. Rev., 1983; p 190-192
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    Stratocumulus simulations with a general circulation model (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: Stratus and stratocumulus cloud sheets which are among the most common cloud types over the world are discussed. They are characteristic of the undisturbed subtropical marine boundary layer over the eastern oceans, where cool water and large scale sinking motion suppress penetrative cumulus convection. They also occur over the Arctic Ocean, particularly in summer, and behind cold outbreaks over the western oceans in winter. Observational studies were conducted and further observations are planned.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Res. Rev., 1983; p 222-226
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  • 66
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    Influence of surface roughness of a desert (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: A numerical simulation study, using the current GLAS climate GCM, was carried out to examine the influence of low bulk aerodynamic drag parameter in the deserts. The results illustrate the importance of yet another feedback effect of a desert on itself, that is produced by the reduction in surface roughness height of land once the vegetation dies and desert forms. Apart from affecting the moisture convergence, low bulk transport coefficients of a desert lead to enhanced longwave cooling and sinking which together reduce precipitation by Charney's (1975) mechanism. Thus, this effect, together with albedo and soil moisture influence, perpetuate a desert condition through its geophysical feedback effect. The study further suggests that man made deserts is a viable hypothesis.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Res. Rev., 1983; p 329-334
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    Two contrasting Northern Hemisphere winters: 1980 - 1981 and 1981 - 1982 (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Seasonal statistics calculated from daily operational analyses by the European Centre for Medium Range Weather Forecasts for December 1980 - February 1981 (season 1) and December 1981 - February 1982 (season 2) were used to contrast the two seasonal mean circulation patterns present in the Northern Hemisphere and to investigate possible causes for the differences. The vertically averaged seasonal mean zonal wind and E-vector, a measure of the anisotropy of the transient eddies over the Pacific is shown for season 1 and season 2. The pattern in season 2, but not season 1, resembles that found in a modeling study of barotropic instability. One possible explanation for the differences between season 1 and 2 is a weak change in tropical heating associated with the southern oscillation, the effect of which in midlatitude was amplified by the occurrence of barotropic instability over the Pacific in season 2, but not season 1.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Res. Rev., 1983; p 209-214
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    An ensemble formulation of PBL fluxes in a GCM (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: An ensemble approach is applied to Planetary Boundary Layer (PBL) calculations with the bulk Richardson number identified as the key parameter. An ensemble averaging calculation was carried out to rederive the bulk friction and heat transport coefficients for the mean condition. Two simulations are carried out and compared. Significant differences in PBL fluxes low level cloudiness, land surface roughness heights, and surface evaporation are noted between the modified and unmodified simulations. Modifications to the model were: (1) the relationship between actual and potential Effective Temperature (ET) to accord with Sud and Fennessy (1982); (2) maximum permissible instantaneous ET at any time is 1.5 mm per hr; (3) moisture distribution in low level cumulus convection to be consistent with no precipitation; (4) appearance of supersaturation clouds to be consistent with supersaturation condition at that level; (5) invoking a simple function for stomatal diffusion effect in the ET calculation.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Res. Rev., 1983; p 270-274
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    Ultraviolet observations of solar flares from the Solar Maximum Mission (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The results of observations of solar flares, obtained by means of the UV Spectrophotometer and Polarimeter (UVSP) instrument on board the Solar Maximum Mission satellite are summarized and discussed. The results are grouped into three main topics: (1) plasma diagnostics in the flare transition zone plasmas, (2) spatial and temporal evolutions of the UV and hard X-ray bursts, and (3) energy release processes in the impulsive phase. The methods of spectral UV analysis, comparison with the hard X-ray burst results, and the interpretation of the results are summarized. It is concluded that the energy release processes in the flare phase can be best interpreted in terms of multiple large and small interloops interacting with each other either mechanically or inductively. Furthermore, the majority of impulsive UV and hard X-ray bursts occurs in small compact loops with high densities and transition-zone temperatures. The impulsive hard X-ray and UV bursts are emitted by nonthermal particles, accelerated by the loop interactions and impinging on the footpoints of these loops.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Societa Astronomica Italiana, Memorie (ISSN 0037-8720); 55; 4, 19; 663-672
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    Results from the Ultraviolet Spectrometer and Polarimeter Non-flare investigations (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: A brief review is given of non-flare investigations using data obtained by the Ultraviolet Spectrometer and Polarimeter on the Solar Maximum Mission. The major topics described are sunspot research including magnetic field measurements, oscillations, and models; mass motions in quiet and active regions including steady flows and acoustic waves; and prominence research including physical conditions, dynamics, and mass motions around prominences. Also discussed are studies of UV bursts, the formation of the Cl I line at 1351 A, ozone in the terrestrial atmosphere, and active regions using correlated observations from other instruments on the spacecraft or on the ground.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Societa Astronomica Italiana, Memorie (ISSN 0037-8720); 55; 4, 19
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    Thermal modeling of Halley's Comet (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The comet thermal model of Weissman and Kieffer is used to calculate gas production rates and other parameters for the 1986 perihelion passages of Halley's Comet. Gas production estimates are very close to revised pre-perihelion estimates by Newburn based on 1910 observations of Halley; the increase in observed gas production post-perihelion may be explained by a variety of factors. The energy contribution from multiply scattered sunlight and thermal emission by coma dust increases the total energy reaching the Halley nucleus at perihelion by a factor of 2.4. The high obliquity of the Halley nucleus found by Sekanina and Larson may help to explain the asymmetry in Halley's gas production rates around perihelion.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Advances in Space Research (ISSN 0273-1177); 4; 9, 19; 221-224
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    IRAS observations of cometary dust (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: It is pointed out that solid material present in the coma and tail of a comet is revealed by the scattering of sunlight and thermal emission of absorbed solar radiation. The large beam size and low background of the cold Infrared Astronomy Satellite (IRAS) telescope make it extremely well suited to the measurement of faint diffuse thermal emission from solid grains associated with comets. The IRAS project was conducted jointly by the Netherlands, the United Kingdom, and the U.S. Its basic objective involved a survey of the sky in four wavelength regions centered on 12, 25, 60, and 100 microns. The present paper is mainly concerned with IRAS observations of the coma-nucleus regions as defined by the maximum in the intensity distribution. Attention is given to circumstances of comet observations, dust production rates, and a discussion of the results.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Advances in Space Research (ISSN 0273-1177); 4; 9, 19
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    A comparison of the dust properties in recent periodic comets (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Measurements of the thermal emission from the cometary dust coma can be used to derive the rate of dust production from the nucleus as well as the size distribution of absorbing grains. More than ten short-period comets have now been observed in the infrared over a wide range in heliocentric distance. Dust production rates are derived for these comets based on theoretical models of the thermal emission from small absorbing grains and calculations of dust grain velocities. The mean size and albedo of the dust grains is similar in these comets, with the exception of Comet Crommelin, which seems to have had larger, darker grains.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Advances in Space Research (ISSN 0273-1177); 4; 9, 19; 189-196
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    A new calibration of the semi-empirical photometric theory for Halley and other comets (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The semiempirical photometric theory of gas and dust production in comets (Newburn, 1979, 1981, and 1982) is recalibrated on the basis of the 17-comet compilation of spectrophotometric data of Newburn and Spinrad (1984). The results are presented in graphs and tables, and it is shown that no corrections are required for the constant R and the function delta, but that the mixing ratios (obtained as functions of heliocentric distance) can be improved, with implications for the visual-photometric comet model. Recently calculated light curves for comet Halley are compared, and the use of the nearly identical curves of Bortle and Morris (1984) and Marcus (1983) is recommended.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Advances in Space Research (ISSN 0273-1177); 4; 9, 19; 185-188
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    Observations of solar radio bursts from meter to kilometer wavelengths (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: New results obtained with the Clark Lake multifrequency radioheliograph at meter-decameter wavelengths and from satellite multifrequency directive observations at hectometer and kilometer wavelengths are reviewed. Evidence is presented that type III electrons propagate in dense coronal streamers and that frequently observed microbursts (presumably type III) at meter-decameter wavelengths are due to plasma radiation. Observations of hectometer and kilometer type III radio storms which reveal information about active region structures, the interplanetary magnetic field configuration, and solar wind acceleration are discussed. Kilometer type II bursts and interactions between type III electrons and interplanetary shocks are examined, and some new results on shock-associated events are presented.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Advances in Space Research (ISSN 0273-1177); 4; 7, 19
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    Combined analysis of soft and hard X-ray spectra from flares (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: An attempt is made to develop a self-consistent model which accounts for the line and continuum data generated by the three X-ray imaging instruments on the SMM satellite. The intensities measured covered the 4-500 kV energy range. The model is based on a differential emission measure and electron beam parameters and is used to predict absolute signals detected by the 15 channels of the SMM sensors. Consideration is given to the thermal contribution, instrumental characteristics, thin target excitation and thick target bremsstrahlung. In comparison with data from a flare event on June 29, 1980, model predictions provide a good fit, including the identification of hard electrons with a 5.3 index during the impulsive phase.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Advances in Space Research (ISSN 0273-1177); 4; 7, 19
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    Flare build-up study - Homologous flares group. I (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Solar Maximum Mission observations have been used to study the origin and amount of energy, mechanism of storage and release, and conditions for the occurrence of solar flares, and some results of these studies as they pertain to homologous flares are briefly discussed. It was found that every set of flares produced 'rafales' of homologous flares, i.e., two, three, four, or more flares separated in time by an hour or less. No great changes in macroscopic photospheric patterns were observed during these flaring periods. A quantitative brightness parameter of the relation between homologous flares is defined. Scale changes detected in the dynamic spectrum of flare sites are in good agreement with a theoretical suggestion by Sturrock. Statistical results for different homologous flare active regions show the existence in homologous flaring areas of a 'pivot' of previous filaments interpreted as a signature of an anomaly in the solar rotation.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Advances in Space Research (ISSN 0273-1177); 4; 7, 19
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  • 78
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    Computation of solar magnetic fields from photospheric observations (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The observational difficulties of obtaining the magnetic field distribution in the chromosphere and corona of the sun has led to methods of extending photospheric magnetic mesurements into the solar atmosphere by mathematical procedures. A new approach to this problem presented here is that a constant alpha force-free field can be uniquely determined from the tangential components of the measured photospheric flux alone. The vector magnetographs now provide measurements of both the solar photospheric tangential and the longitudinal magnetic field. This paper presents derivations for the computation of the solar magnetic field from these type of measurements. The fields considered are assumed to be a constant alpha force-free fields or equivalent, producing vanishing Lorentz forces. Consequently, magnetic field lines and currents are related by a constant and hence show an identical distribution. The magnetic field above simple solar regions are described from the solution of the field equations.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Solar Physics (ISSN 0038-0938); 94; 219-234
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  • 79
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    Comments on 'Inference of cloud temperature and thickness by microwave radiometry from space' (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The method proposed by Pandey et al. (1983) for estimating the temperature differential and thickness of clouds from microwave data obtained with the scanning multichannel microwave radiometers of the Seasat and Nimbus-7 satellites is examined critically. It is pointed out that both the thicknesses and the temperature differentials derived from them may not be meaningful unless accurate measurements of cloud-top height (from IR radiometry) and reliable data on liquid-water content are available. It is suggested that the good fits obtained in generating regression coefficients for the proposed method may be artifacts of the fixed or limited-range liquid-water densities of the cloud models used. With respect to cloud-top height, the need to quantify and account for differences in the fields of view and spatial resolutions of the IR and microwave radiometers, as undertaken for the case of precipitating clouds by Yeh and Liou (1983), is stressed.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Journal of Climate and Applied Meteorology (ISSN 0733-3021); 23; 1579
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  • 80
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    The diurnal variation of Atlantic Ocean tropical cyclone cloud distribution inferred from geostationary satellite infrared measurements (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Monthly Weather Review (ISSN 0027-0644); 112; 2338-234
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  • 81
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    Delineating mid- and low-level water vapor patterns in pre-convective environments using VAS moisture channels (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Infrared and visible imagery from VAS are used to delineate mid- and lower-tropospheric moisture fields for a variety of severe storm cases in the southern and central United States. The ability of sequences of images to isolate areas of large negative vertical moisture gradients and apparent convective instability prior to the onset of convective storms is assessed. A variety of image combination procedures are used to deduce the stability fields which are then compared with the available radiosonde data. The results for several severe storm cases indicate that VAS can detect mid- and low-level mesoscale water vapor fields as distinct radiometric signals. The VAS imagery shows a strong tendency for thunderstorms to develop along the edges of bands of midlevel dryness as they overtake either preexisting or developing low-level moisture maxima. Image sequences depict the speed with which deep moist and dry layers can develop and move.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Monthly Weather Review (ISSN 0027-0644); 112; 2178-219
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  • 82
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    Stratocumulus cloud field reflected fluxes - The effect of cloud shape (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The reflected fluxes of stratocumulus cloud fields are calculated as a function of sky cover aspect ratio and cloud shape. In order to obtain a better fit with general circulation models (GCMs), cloud liquid water volume values were kept invariant relative to cloud shape. On the basis of the required accuracy of the Earth Radiation Budget Experiment (ERBE), an order of magnitude value of 10 W per sq m was used to estimate the difference between plane-parallel and broken cloudiness reflected fluxes. An empirical relationship for effective cloud cover at a solar zenith angle of 60 deg is derived. The relationship allows for the accurate computation of broken cloud field reflected fluxes using plane-parallel calculations. It is predicted that more accurate estimates of broken cloud field radiative properties may be possible in the future.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Journal of the Atmospheric Sciences (ISSN 0022-4928); 41; 3085-310
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  • 83
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    On the dynamics of stratocumulus formation and dissipation (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Results obtained with a mixed layer model are used to study the dynamics of stratocumulus formation and dissipation in subtropical marine stratocumulus cloud regimes. The model used allows entrainment to be driven by shear as well as buoyancy, and includes a very crude parameterization of the partial blackness of thin cloud layers. Model results show that for some values of the large-scale divergence there are three equilibrium mixed layer structures, two of which are stable. One of the stable equilibria is cloudy, deep, and buoyancy-driven, while the other is clear, shallow, and shear-driven. It is found that as a result of hysteresis effects a transient increase in the large-scale divergence can produce a long-lasting break in the clouds.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Journal of the Atmospheric Sciences (ISSN 0022-4928); 41; 3052-305
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  • 84
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    Modeling the middle atmosphere circulation (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Some of the motivations for constructing models of the middle atmosphere circulation are given. These are as follows: (1) to provide a better understanding of middle atmosphere dynamics; (2) to study the coupling of middle atmosphere dynamics with radiation and chemistry; (3) to study the sensitivity of tropospheric climate modeling and/or weather forecasting to changes in the middle atmosphere; (4) to better understand the limitations of more simplified models; (5) to supply a proxy for atmospheric data for diagnostic analysis; and finally, (6) for forecast-analysis of data. Different types of models are discussed in relation to their anticipated use. Various model simplifications, such as using the quasi-geostrophic set of equations and simplified radiative transfer, are discussed as are some of the consequences of these simplifications. Some of the accomplishments of middle atmosphere circulation modeling are presented as are some of the difficulties in existing models. Finally, some of the problems in constructing and verifying middle atmosphere circulation models are discussed.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
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  • 85
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    On Bowen enhancement of the N III spectrum under solar and nebular conditions (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Expected enhancement of the N III emission-line spectrum by the Bowen He II to O III to N III resonant photoexcitation process is computed using a six-configuration model. Preliminary comparisons with available solar and nebular observations indicate that the process may play only a small role, although photoexcitation quenching of the N III and O III far-infrared fine-structure lines is noted as a possibly important mechanism. Some features are discussed in connection with the nebular emission at 1750 A, which is suggested as an indicator of excitation class for planetary nebulae.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 287; 945-951
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  • 86
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    The energetics of chromospheric evaporation in solar flares (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The Solar Maximum Mission (SMM) spacecraft has provided high time resolution observational data regarding the soft X-ray emission from solar-flare plasma during 1980. The present investigation is concerned with the characteristics of a soft X-ray flare and the energetics of the impulsive phase on the basis of the data collected with the aid of two of the instruments on board the SMM, taking into account the Hard X-ray Burst Spectrometer (HXRBS) and the Bent Crystal Spectrometer (BCS). Attention is given to an analysis of soft X-ray flare spectra, the relative motion of the soft X-ray sources, the phenomenology of the soft X-ray flare, energy and mass transport during the impulsive phase, and energy deposition in the chromosphere during evaporation.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 287; 917-925
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  • 87
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    The 41.5 day binary X-ray pulsar 4U 1223 - 62 (GX 301 - 2) (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Ariel 5 and SAS 3 X-ray pulse timing data for the 700 s X-ray pulsar 4U 1223 - 62 (GX 301 - 2) are reexamined in order to deduce the orbital elements of this system. The Ariel 5/SAS 3 arrival times are first reanalyzed to obtain the best solution for an orbital period close to 41.5 days and to estimate the uncertainties in it caused by unknown variations in the underlying pulse period. Spectral measurements by OSO 8 and HEAO 1 at a variety of orbital phases are presented and the origin of an unabsorbed, unpulsed soft component is discussed. OSO 8 observations of occasions when the amplitude and shape of the pulse profile changed dramatically are discussed. The global X-ray properties of the system are explained in terms of a simple stellar wind accretion model, and the interaction of the inflowing material with the neutron star magnetosphere is considered.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 287; 856-867
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  • 88
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    Similar photospheres, different mantles - A study of four O stars (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The present investigation is concerned with a comparison of the spectra of four O stars (10 Lac, S Mon, HD 46223, and Zeta Pup) which have similar effective temperatures, taking into account an attempt to find the reason for differences regarding the spectral type of the stars. The photospheres of the stars are examined, taking into account the effective temperatures, radii, speed of rotation, and masses. Information is presented about the equivalent widths and profiles of strong lines in the visible and ultraviolet spectra of each star. It is found that the four stars have similar photospheres but different mantles. The stars are assigned different spectral types because the empirically selected lines used for determining spectral type in class O are sensitive primarily to conditions in the mantle of the star and not to conditions in the photosphere. Questions concerning the reasons for the differences regarding the mantles are also explored.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 287; 874-891
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  • 89
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    Absorption features in the 5-8 micron spectra of protostars (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: High signal-to-noise ratio spectra in the range of 5-8 microns of four sources embedded in molecular clouds are examined using low-temperature laboratory measurements of the 5-8-micron spectra of simple molecules and their mixtures. The absorption, apparent in all four sources, is characterized by highly distinct features ranging from two relatively narrow bands at 6.0 and 6.8 microns in W33A to a broad, shallow, and partially structured feature extending from 5.2 to 7.8 microns in Mon R2-IRS2, BN, and NGC2264. The first feature (W33A) is explained by the OH bending mode in H2O and the CH deformation modes in saturated hydrocarbons; while the second feature (Mon R2-IRS2-type) is explained by the presence of a mixture of saturated and unsaturated hydrocarbons possibly containing strongly electronegative groups.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 287; 697-706
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  • 90
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    Self-absorption of high-energy Gamma-rays in Cygnus X-3 (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Absorption of high-energy gamma-rays from Cyg X-3 in its own photon field by the reaction gamma + gamma yields e(+) + e(-) is considered. It is found that gamma rays with an energy around 10 to the 12th eV are attenuated, and the observed flux has to be corrected. Gamma rays with energy greater than 10 to the 15th eV which are observed are not affected by the photon field.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 287; 338-340
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  • 91
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    Monte Carlo shock-like solutions to the Boltzmann equation with collective scattering (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The results of Monte Carlo simulations of steady state shocks generated by a collision operator that isotropizes the particles by means of elastic scattering in some locally defined frame of reference are presented. The simulations include both the back reaction of accelerated particles on the inflowing plasma and the free escape of high-energy particles from finite shocks. Energetic particles are found to be naturally extracted out of the background plasma by the shock process with an efficiency in good quantitative agreement with an earlier analytic approximation (Eichler, 1983 and 1984) and observations (Gosling et al., 1981) of the entire particle spectrum at a quasi-parallel interplanetary shock. The analytic approximation, which allows a self-consistent determination of the effective adiabatic index of the shocked gas, is used to calculate the overall acceleration efficiency and particle spectrum for cases where ultrarelativistic energies are obtained. It is found that shocks of the strength necessary to produce galactic cosmic rays put approximately 15 percent of the shock energy into relativistic particles.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 286; 691-701
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  • 92
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    The collapse of the cores of slowly rotating isothermal clouds (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: A generalized model which accounts for the effects of initially uniform and slow rotation is defined for the spherical collapse of a singular isothermal sphere such as protosolar and binary nebulae. An initial unstable equilibrium state is described for a sound speed of 0.35 km/sec and a rotation rate of 10 to the -14th/sec for the molecular cloud surrounding the accreting core. The total angular momentum and mass of the inner cloud is set equal to solar system values. The evolution of the collapse is traced by applying a perturbation analysis to the similarity solution for a nonrotating condition, and matched asymptotic expansions solve the hydrodynamic equations. The model is concluded a valid tool for studying star and nebular disk formation.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 286; 529-551
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  • 93
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    Evidence for a supersonic turbulent velocity gradient in the outer photosphere of the supergiant alpha Cygni (A2Ia) (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The balloon-borne UV Stellar Spectrometer's high resolution, near-UV spectra of the supergiant Alpha Cyg are subjected to analysis in order to determine the average microturbulent line-of-sight velocity component. A value of 15.0 + or - 0.5 km/sec is obtained, which is close to the 13.7 km/sec local sound velocity, and is consistent with the view that shock waves are the dominant structure in the outer photosphere of Deneb, so that shock wave dissipation determines the thermal structure of the photosphere.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astronomy and Astrophysics (ISSN 0004-6361); 141; 2, De
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  • 94
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    Dynamic evolution of recurrent mass ejections observed in H-alpha and C IV lines (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The mass ejections of 1 September, 1980 are studied from observations obtained with the MSDP spectrograph and with the Ultraviolet Spectrometer and Polarimeter aboard the Solar Maximum Mission satellite. The analysis is focused on observations in the chromospheric H-alpha line and the transition region C IV 1548 A line. It is noted that cold and hot material had the same projection, although the upward C IV velocity structure was more extended than the H-alpha one. It is shown that the observed contrast of the H-alpha absorbing structure can be interpreted in terms of a dynamic cloud model overlying the chromosphere. Radial velocities of 25-30 km/s and -40 km/s are estimated for the first and second phases of ejection, respectively.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Solar Physics (ISSN 0038-0938); 94; 133-150
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  • 95
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    Stratocumulus cloud deepening through entrainment (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Under a substantial range of realistic conditions, stratocumulus cloud top entrainment is noted to either deepen an existing cloud layer or produce clouds in an unsaturated mixed layer, though the entrained air is warmer and drier than the mixed-layer air. These results, which apply irrespective of entrainment rate-determining mechanism, imply that the cloud top entrainment instability discussed by Randall (1980) and Deardorff (1980) does not necessarily destroy a layer cloud. Examples are given which include soundings, marine layer data, and simulation results produced by the UCLA general circulation model.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Tellus, Series A - Dynamic Meteorology and Oceanography (ISSN 0280-6495); 36A; 446-457
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  • 96
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    An intercalibration of Meteosat-1 and GOES-2 visible and infrared measurements (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: An intercomparison between radiative parameters determined from visible and infrared channels of the Meteosat-1 and GOES-2 geosynchronous satellites has been carried out using data obtained over the central Atlantic Ocean for 5 November 1978. Hourly visible-infrared measurement pairs at a nominal resolution of 5 km (Meteosat) or 8 km (GOES) have been stored in 1 deg x 1 deg longitude-latitude regions. For the infrared intercomparisons, the GOES 11.5 micron radiance has been compared to Meteosat infrared counts. The scatter in partly cloudy regions is interpreted as being caused by meteorological differences arising from differences in measurement time between the two data sets. For the visible intercomparison, the GOES measurements for clear and cloudy scenes have first been converted with the aid of scene-dependent angular reflectance and albedo models to estimates of the filtered shortwave radiance that GOES would have measured had it been in the Meteosat position. This value has then been compared to Meteosat counts for the shortwave channel. The results indicate that earlier Meteosat calibrations made from airplane overflights of a limited variety of surfaces are applicable to much larger areas of cloud and ocean.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: Journal of Atmospheric and Oceanic Technology (ISSN 0739-0572); 1; 283-286
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  • 97
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    Outlook for research on subtropical marine stratiform clouds (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: A detailed description of the goals and methodology of the First International Satellite Cloud Cover Project Regional Experiment (FIRE) is presented. The purpose of the experiment is to develop physical models and parameterizations of fractional cloud cover over the Pacific Basin. In order to determine fractional cloud cover parameters, satellite observations by radar and lidar instruments will be combined with in situ measurements of the cloud-capped marine boundary layer. A description of a candidate experiment for the program is presented, and some general problems connected with the statistical characterization of satellite imagery are discussed.
    Schlagwort(e): METEOROLOGY AND CLIMATOLOGY
    Materialart: American Meteorological Society, Bulletin (ISSN 0003-0007); 65; 1290-130
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  • 98
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    Vibrational and rotational excitation of CO in comets Nonequilibrium calculations (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Ultraviolet observations of atomic carbon in cometary comae show that carbon-bearing compounds must comprise a significant fraction (approximately equal to or greater than 10 percent) of the volatiles. One likely source is CO. This compound is an important constituent of at least some cometary nuclei, even though it may not be the ultimate source of atomic carbon in all comets. Feldman (1983) has suggested that the relative abundance of CO may be one of the few fundamental characteristics which distinguish one comet from another. The present investigation is, therefore, concerned with the vibrational and rotational excitation of the CO molecule in cometary comae. Two previously neglected factors are taken into account in the study. The fractional populations of CO as solutions to time-dependent differential equations are derived, and a nonisothermal and cold kinetic temperature profile for the inner coma is considered.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 285; 858-869
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  • 99
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    The ultraviolet variability of early-type supergiants (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Four early-type supergiants - HD 79186 (B5 Ia), HD 96919 (B9 Ia), HD 105056 (ON9.7 Iae), and HD 148379 (B2 Iae) - have been observed with the low-resolution spectrographs of IUE in the large aperture on 14 days. The behavior of the ultraviolet fluxes with time is studied. The light from all four stars seems to vary. Typically the dispersion about the mean magnitude at any wavelength corresponds to + or - 0.085, + or - 0.080, + or - 0.101, and + or - 0.106 mag, respectively. These amplitudes exceed the typical uncertainty in an IUE measurement of flux by about a factor of 3; they are somewhat larger than the variations known in the visible wavelength range. There are insufficient data to investigate periodicity in the observed light changes. The effective temperatures and angular diameters of the stars have been estimated using the present ultraviolet photometry, published UBV and uvby photometry, and the model-atmosphere fluxes reported by Kurucz in 1979. The program stars have dimensions typical for their spectral types. A brief discussion is given of possible causes of the variability of hot supergiants.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 285; 668-673
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    Modification to shock fitting program (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: A modified form of the Lepping-Argentiero single spacecraft, shock normal determination procedure is presented. The modified method incorporates a simple predictor-corrector algorithm which allows a faster convergence rate and the use of average values of the parameters for the starting vector.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 89; 11004-11
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