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  • GEOPHYSICS  (819)
  • 2015-2019
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  • 1
    Publication Date: 2005-02-28
    Keywords: GEOPHYSICS
    Type: Res. in the Space Sci., Vol. 2, No. 1; 29 p
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  • 2
    Publication Date: 2006-05-22
    Description: The relative merits of pressure increment and partial derivative formulations of the ozone inversion problem are discussed briefly. The height range of validity of the retrieved ozone profile and the effects of adding wavelengths to or of dropping wave-length from the inversion system are indicated. Illustrative results are presented for profiles retrieved from BUV data using Backus-Gilbert, minimum information (Twomey), and quasi-optimum procedures.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 577-597
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  • 3
    Publication Date: 2006-05-22
    Description: The inversions of multi-channel solar extinction measurements have been analyzed for the 0.35-1.0 micron wavelength region to retrieve stratospheric aerosol and ozone vertical profiles using both the constrained linear inversion scheme and the iterative scheme. The inversions of the multi-wavelength solar extinction data obtained from spacecraft have been analyzed based on the inversion of computer simulated data using various atmospheric models with differing amounts of aerosol and ozone in the stratosphere. The sensitivities of the inversion schemes to different experimental errors are discussed in terms of accuracy and resolution of the retrieved profiles.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 505-527
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  • 4
    Publication Date: 2006-05-22
    Description: Polarization properties of the angularly scattered laser light from a volume of air are used to determine the size distribution of the aerosol particles within the volume by the use of appropriate inversion techniques. Similar techniques are employed to determine a mean size distribution of the particulates within a vertical column through the atmosphere from determinations of the aerosol optical depth as a function of wavelength. In both of these examples, a modification of an inversion technique originally described by Twomey has been employed. Details of this method are presented as well as results from actual measurements employing bistatic lidar and solar radiometer.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 469-503
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  • 5
    Publication Date: 2006-05-22
    Description: Surface-based observations of downwelling microwave thermal emission are related to temperature and humidity profiles via a standard integral equation of radiative transfer. Both in clear and in cloudy atmospheres, statistical inversion techniques are used to retrieve profiles from a data vector of brightness observations and surface meteorological constraints. For the clear case, accuracy predictions and profile retrievals are illustrated for: (1) single frequency angular scanned data; (2) multi-frequency angular scanned data; and (3) multi-frequency zenith data. For the last case predicted and achieved accuracies were compared in a recently conducted radiometric experiment. Retrievals of cloud contaminated radiometric data are elaborated.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 395-427
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  • 6
    Publication Date: 2006-05-22
    Description: Linear numerical inversion methods applied to atmospheric remote sounding generally can be categorized in two ways: (1) iterative, and (2) inverse matrix methods. However, these two categories are not unrelated; a duality exists between them. In other words, given an iterative scheme, a corresponding inverse matrix method exists, and conversely. This duality concept is developed for the more familiar linear methods. The iterative duals are compared with the classical linear iterative approaches and their differences analyzed. The importance of the initial profile in all methods is stressed. Calculations using simulated data are made to compare accuracies and to examine the dependence of the solution on the initial profile.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 325-360
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  • 7
    Publication Date: 2006-05-22
    Description: An analytic model approach is applied to several simple atmospheric inversion problems. This method gives a sharp determination of aerosol size distribution parameters. It is shown that this analytic approach, together with ground level point sampling data measurements, can be used to infer information on the tropospheric ozone profile.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 297-324
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  • 8
    Publication Date: 2006-05-22
    Description: Limb emission measurements are characterized by sharp weighting functions at high altitudes, and for temperature determinations, strongly nonlinear dependence of the weighting function on the temperature. Several methods for inverting this type of measurement have been described and used, including iterative, statistical, nonlinear and approximate direct approaches. These approaches are described and advantages and disadvantages of each are outlined.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 195-216
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  • 9
    Publication Date: 2006-05-22
    Description: Nonlinear matrix inversion operators have been developed which, applied to observed radiances, infer maximal information regarding atmospheric scattering parameters and vertical distribution of radiant sources and sinks. The algorithm has the attractive feature of noise discrimination, attributing instrumental errors to extra-atmospheric sources.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 139-153
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  • 10
    Publication Date: 2006-05-22
    Description: The inversion method provides a quantitative evaluation of the trade-off between vertical resolution of a retrieved profile and formal root-mean-square (rms) error due to measurement noise propagation. The problem of retrieving the top-side ozone profile from backscattered ultraviolet (BUV) measurements is considered. For measurements of the type currently being obtained with the Nimbus 4 and AE-E BUV experiments, it is found that a vertical resolution of approximately 0.75 scale height can be achieved for a formal volume mixing ratio profile error of 10%. Other examples include treatments of the retrieval of temperature profiles from measurements in the 15 micron CO2 absorption band for both the terrestrial and Martian atmospheres. Finally, the method is applied to the problem of retrieving temperature profiles of the Jovian planets from measurements in the far infrared pressure induced H2 lines to be obtained from the Mariner Jupiter/Saturn fly-by missions.
    Keywords: GEOPHYSICS
    Type: Inversion Methods in Atmospheric Remote Sounding; p 155-193
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  • 11
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    In:  CASI
    Publication Date: 2006-05-22
    Description: Statistical methods are used to deal with the inverse problem of radiative transfer. All the available information about an unknown profile can be expressed in the form of values of functions of that profile and error estimates of these values. Estimation theory shows how these values are combined to give an estimate of the unknown profile and its error covariance. Many inversion methods are expressed in this form, although the error estimate is not usually carried out. Practical applications are described, both for inversion of individual profiles, and the global analysis of satellite data.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 117-138
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  • 12
    Publication Date: 2006-05-22
    Description: Several commonly used methods for inversion--constrained linear inversion, synthesis (Backus-Gilbert) methods and nonlinear iterative techniques for the Chahine type--are discussed. It is demonstrated that a very close connection exists between Backus-Gilbert solutions and those given by constrained linear inversion. A number of examples of the application of such methods are presented, showing that resolution is not greatly different for quite different algorithms, a result quite in accord with general theoretical considerations: more resolution can be achieved at the expense of introducing greater a priori bias in the procedure.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 41-65
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  • 13
    Publication Date: 2006-05-22
    Description: The radiative transfer in a scattering plane-parallel atmosphere is discussed, considering the exact analytical, the computational and the approximate methods. Some results of numerical comparisons are given. Finally, the difficulties of realistic atmospheric models are emphasized.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 21-40
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  • 14
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    Publication Date: 2006-05-22
    Description: Multiple scattering problems in a plane layer often permit the convenient use of different methods joined together. Sample numerical results to illustrate this point refer to X- and Y-functions, asymptotic fitting, the small-loss approximations, polarization in high orders, and photon path distribution.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Inversion Methods in Atmospheric Remote Sounding; p 1-19
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  • 15
    Publication Date: 2006-01-16
    Description: Determinations of tracking station locations and the gravitational constant of the earth, based on Doppler-tracking data from lunar and planetary spacecraft are presented. Two-way Doppler data obtained by the Deep Space Network of the Jet Propulsion Laboratory (JPL) were used. The Deep Space Station instrumentation that JPL employed is described. How the stations were located is detailed, and the data used are discussed. Results are given together with an analysis of the errors.
    Keywords: GEOPHYSICS
    Type: Natl. Geodetic Satellite Program, Pt. 1; p 249-292
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  • 16
    Publication Date: 2006-01-16
    Description: The Applied Physics Laboratory (APL) space research program was directed toward modeling the gravitational field of the earth from an analysis of the Doppler shifts on the transmitted frequencies of the satellites as obtained by the tracking stations. Emphasis is on the satellites involved and the methods used in accomplishing this aim.
    Keywords: GEOPHYSICS
    Type: NASA, Washington Natl. Geodetic Satellite Program, Pt. 1; p 89-138
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  • 17
    Publication Date: 2006-01-12
    Description: The basic concepts relating to displacement fields associated with earthquakes are described. Factors discussed include: understanding the geologic and tectonic setting, the discovery of fault creep, and an extended range of possible models of strain buildup. Problems in tectonic modeling reviewed relate to understanding (1) frictional heat generation on faults, (2) the character of stress and strain on faults below the depth of earthquakes, and (3) the predictability of major earthquakes.
    Keywords: GEOPHYSICS
    Type: Ohio State Univ. Res. Found. Proc. of the Geodesy/Solid Earth and Ocea; 103-110
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  • 18
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    Publication Date: 2006-01-12
    Description: The principles and problems relative to the determination of the geoid are outlined. Factors discussed include: gravity data requirements for a precise geoid; mean sea level; and satellite altimetry. It is indicated that geoid undulations can be determined on a global basis to plus or minus 3 m. Application of geoid information to oceanography and the determination of sea surface topography considered.
    Keywords: GEOPHYSICS
    Type: Proc. of the Geodesy/Solid Earth and Ocean; 69-77
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  • 19
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    Publication Date: 2006-01-12
    Description: The OGO 3 spacecraft characteristics are briefly described. Brief descriptions of experiments are presented along with bibliographies of papers pertaining to these experiments.
    Keywords: GEOPHYSICS
    Type: OGO Program Summary; 8 p
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  • 20
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    Publication Date: 2006-01-12
    Description: The OGO 2 spacecraft characteristics are briefly described. Brief descriptions of experiments are presented along with a bibliography of papers pertaining to that experiment.
    Keywords: GEOPHYSICS
    Type: OGO Program Summary; 7 p
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  • 21
    Publication Date: 2006-01-16
    Description: Background for the National Geodetic Satellite Program (NGSP) is presented. An historical summary of the program and its technical structure is given. The technical structure of the program is described in enough detail that the reader can relate the work of the individual contributors to each other and to the NGSP.
    Keywords: GEOPHYSICS
    Type: NASA, Washington Natl. Geodetic Satellite Program, Pt. 1; p 3-85
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  • 22
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    Publication Date: 2006-01-12
    Description: The OGO 6 spacecraft characteristics are briefly described. Brief descriptions of experiments are presented along with bibliographies of papers pertaining to each experiment.
    Keywords: GEOPHYSICS
    Type: OGO Program Summary; 9 p
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  • 23
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    Publication Date: 2006-01-12
    Description: The OGO 5 spacecraft characteristics are briefly described. Brief descriptions of experiments are presented along with bibliographies of papers pertaining to each experiment.
    Keywords: GEOPHYSICS
    Type: OGO Program Summary; 10 p
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  • 24
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    Publication Date: 2006-01-12
    Description: The objectives and background, approach and mission profiles are discussed along with the configuration, and accomplishments of the program. The results of experiments for OGO 1,2,3, and 4 are presented.
    Keywords: GEOPHYSICS
    Type: OGO Program Summary; 27 p
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  • 25
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    Publication Date: 2006-01-12
    Description: The OGO 4 spacecraft characteristics are briefly described. Brief descriptions of experiments are presented along with bibliographies of papers pertaining to each experiment.
    Keywords: GEOPHYSICS
    Type: OGO Program Summary; 8 p
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  • 26
    Publication Date: 2006-01-12
    Description: The OGO 1 spacecraft characteristics are briefly described. Brief descriptions of experiments are presented along with bibliographies of papers pertaining to that experiment.
    Keywords: GEOPHYSICS
    Type: OGO Program Summary; 8 p
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  • 27
    Publication Date: 2006-01-16
    Description: The major accomplishments of the GEOS-B, C-band systems project is assessed. The project objectives are given, namely: (1) primary objectives that must be met for project success; (2) secondary objectives that were sufficiently important to warrant serious consideration; and (3) other objectives that were important to the project and for which additional effort would be desirable. The primary objectives are presented and discussed in detail.
    Keywords: GEOPHYSICS
    Type: Natl. Geodetic Satellite Program, Pt. 1; p 487-524
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  • 28
    Publication Date: 2006-01-16
    Description: Equipment and techniques were evaluated operationally, by the Department of Defense, during the National Geodetic Satellite Program (NGSP). The theory, instrumentation, and data reduction methods used are described. Results obtained during the NGSP are given.
    Keywords: GEOPHYSICS
    Type: NASA, Washington Natl. Geodetic Satellite Program, Pt. 1; p 139-245
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  • 29
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    Publication Date: 2006-01-12
    Description: The state-of-the-art technology in the study of the three dimensional rotation of the earth about its center of mass is summarized. A survey of appropriate reference frames and problems involved in defining them is given along with an outline of the accuracy with which the earth's rotation can be measured relative to these frames. The various spectral features of changes in the axis orientation and spin rate of the solid earth and the physical mechanisms known or likely to effect and/or affect them are discussed.
    Keywords: GEOPHYSICS
    Type: Ohio State Univ. Res. Found. Proc. of the Geodesy/Solid Earth and Ocean; 27-39
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  • 30
    Publication Date: 2006-01-11
    Description: Visual observations, as made by cosmonauts, of the earth's surface, physical processes occurring in the earth's atmosphere, and optical phenomena are discussed.
    Keywords: GEOPHYSICS
    Type: Mod. Achievements of Cosmonautics (NASA-TT-F-16221); p 51-56
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  • 31
    Publication Date: 2011-08-16
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 80; Oct. 1
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  • 32
    Publication Date: 2011-08-16
    Description: Simultaneous observations during four substorms are reported from the Lockheed auroral particle spectrometer on ATS-5 and the University of Alberta meridian magnetometer chain (Canada). During the four events studied, there was a good correlation between the magnitude of the trapped electron fluxes in the energy range from 1.8 to 53 keV and the magnitude of the electrojet current as measured by a station in the magnetometer chain at a latitude close to that expected for the ATS conjugate point. The Hall effect was studied and a model electrojet was constructed which gave a good absolute agreement between the two measured quantities. The results are consistent with the convection electric field remaining approximately constant during a substantial portion of each of the substorms studied. The temporal variations of the electrojet were apparently controlled by conductivity changes in the ionosphere as determined by the precipitating auroral electrons.
    Keywords: GEOPHYSICS
    Type: Analysis of Data from the Lockheed Experiment on ATS-5; 24 p
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  • 33
    Publication Date: 2011-08-16
    Description: Measurements of NH3 absorption coefficients are presented for several transitions of a C-13(O-16)2 laser for small concentrations of NH3(p less than 1 torr) for absorption lines broadened to 1 atm with N2. NH3 absorption coefficients were determined for laser transitions R(8)(920.2194 wavelengths/cm) to R(28)(933.8808 wavelengths/cm) of the 00 1 - (10 0,02 0)I band. The strongest absorption coefficient K = 36.09 + or - 1.43 per (atm-cm) was measured for the R(18) transition for the NH3 line, aQ(6,6), and is larger than has been found in any previous measurements with a CO2 laser. The dependence of K on total pressure was also obtained for select transitions, and the frequency separation between the R(18) laser transition and the neighboring NH3 line aQ(6,6) was determined to be 550 + or - 50 MHz. These results are significant for long path absorption monitoring of NH3 with CO2 lasers since the path length can be reduced by approximately 40% and for heterodyne detection of NH3 since the relative position of the laser transition to the NH3 absorption line is well within the bandpass of Hg-Cd-Te photomixers.
    Keywords: GEOPHYSICS
    Type: Applied Optics; 14; Sept
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  • 34
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    Publication Date: 2011-08-16
    Description: A brief review is presented of recent progress made toward gaining a more complete understanding of the thermal structure of the ionosphere. Important heat sources for the ionosphere are described, including the solar EUV flux, midlatitude interactions between the magnetosphere and ionosphere, electric-field enhancements at high latitudes, particle precipitation in the auroral oval, and polar-wind heating. Discrepancies between electron-temperature measurements by satellite probes and incoherent-backscatter techniques are noted.
    Keywords: GEOPHYSICS
    Type: Reviews of Geophysics and Space Physics; 13; July 197
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  • 35
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    Publication Date: 2011-08-16
    Description: The complex interaction of the cold plasma of the plasmasphere and ionosphere with the hot plasma of the ring current and the plasma sheet is studied. It is seen that a coupling, probably through wave particle interactions, exists which seems to have a strong influence on the temperature of the plasma of the outer plasmasphere and on the detailed dynamics of the bulge region, especially the formation of detached plasma regions or plasma tails. Also, there is evidence that the outer plasmasphere may display very high temperatures, and that detached plasma regions are closely associated with ring current injections.
    Keywords: GEOPHYSICS
    Type: Reviews of Geophysical and Space Physics; 13; July 197
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  • 36
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    Publication Date: 2011-08-16
    Description: Questions of radiative transfer in realistic atmospheres are considered along with aspects related to radiative energy budgets and the solar constants, the radiative properties of atmosphere and surfaces, radiation instruments and measurements, and radiative interactions in dynamical systems. A number of special topics are discussed, taking into account remote sensing, air pollution, and the effect of turbulence on the propagation of light through the atmosphere. It is pointed out that numerous recent studies have been conducted of the properties and effects of atmospheric aerosols.
    Keywords: GEOPHYSICS
    Type: Reviews of Geophysics and Space Physics; 13; July 197
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  • 37
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    Publication Date: 2011-08-16
    Description: Riometric and forward-scatter radio-wave absorption measurements at high polar latitudes in both hemispheres are compared with absorption calculations based on satellite observations in the magnetosheath to determine whether a north-south asymmetry in the solar electron flux occurred during a polar-cap absorption (PCA) event. Detection of solar electrons in interplanetary space is shown to have occurred simultaneously with detection of HF radio-wave absorption, indicating that the initial stage of the PCA was due to the arrival of solar electrons. A north-south asymmetry is observed in the electron flux, and it is found that the flux precipitating over the South Pole did not exceed the mean unidirectional intensity of the electrons detected in space. The ratio between fluxes in the low and high polar latitude regions over Antarctica during a period of solar electron anisotropy is found to be comparable with that obtained during periods of isotropy. These results are shown to be consistent with the idea of an open magnetosphere and with the conclusion that an anisotropic solar electron flux may be rendered isotropic at the magnetopause.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science; 23; June 197
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  • 38
    Publication Date: 2011-08-16
    Keywords: GEOPHYSICS
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  • 39
    Publication Date: 2011-08-16
    Description: Two cyclic ethers have been identified for the first time from insoluble polymer-like kerogen in a Precambrian rock by ozonolysis, gas chromatography, and mass spectrometry. The ethers are 2-n-propyl-3-methyltetrahydrofuran and 2-n-propyltetrahydropyran. These compounds could prove to be the oldest indigenous biochemical fossils. The sample was obtained 750 m stratigraphically above the base of the Transvaal Sequence from an outcrop approximately 315 km north-east of Johannesburg, South Africa.
    Keywords: GEOPHYSICS
    Type: Nature; 255; June 26
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  • 40
    Publication Date: 2011-08-16
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 80; June 1
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  • 41
    Publication Date: 2011-08-16
    Description: Explorer 43 data were used to study 34 bow shock crossings observed from 5 to 16 earth radii upstream of the average bow shock location. Waves with periods of 6 to 130 s having amplitudes up to delta-B/B = 1 were detected. Wave polarization for the low-frequency waves is right-handed in relation to the average field direction when the observer moves from the upstream to downstream direction but is left-handed when the observer moves in the opposite sense. This fact identified the waves as standing whistler waves in the coordinate system of the shock. The waves are in agreement with collisionless low Mach number laminar shock theory. When the measured parameters were used to calculate theoretical wavelengths, the observed wave frequencies could be used to calculate velocities for the shock-wave coordinate system past the spacecraft; such velocities are mostly between 10 and 30 km/s. It is suggested that the higher-frequency propagating whistler waves may evolve from the standing whistler waves through a decay instability.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 80; Feb. 1
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  • 42
    Publication Date: 2011-08-16
    Description: The equations of horizontal motion of the neutral atmosphere between 120 and 500 km are integrated with the inclusion of all nonlinear terms of the convective derivative and the viscous forces due to vertical and horizontal velocity gradients. Empirical models of the distribution of neutral and charged particles are assumed to be known. The model of velocities developed is a steady state model. In Part I the mathematical method used in the integration of the Navier-Stokes equations is described and the various forces are analyzed. Results of the method given in Part I are presented with comparison with previous calculations and observations of upper atmospheric winds. Conclusions are that nonlinear effects are only significant in the equatorial region, especially at solstice conditions and that nonlinear effects do not produce any superrotation.
    Keywords: GEOPHYSICS
    Type: Journal of Atmospheric and Terrestrial Physics; 37; Feb. 197
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  • 43
    Publication Date: 2011-08-16
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 80; Jan. 1
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  • 44
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    Publication Date: 2011-08-17
    Description: The reported discussion is concerned with longitudinal waves associated with electron motions. These waves are easily stimulated in the ionosphere by rocket- and satellite-borne RF sounders. Most of the observations of stimulated plasma waves in the ionosphere are based on ionograms obtained from the sounders carried on board five satellites, including Explorer 20, Alouette 1 and 2, and ISIS 1 and 2. The majority of the observations can be explained by considering the propagation of the sounder-stimulated plasma waves. Attention is given to aspects of plasma wave dispersion, linear phenomena, plasma wave instabilities and nonlinear phenomena, unexplained phenomena, diagnostic applications, geophysical and astrophysical applications, and a number of experiments planned for the future.
    Keywords: GEOPHYSICS
    Type: Radio Science; 12; Nov
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  • 45
    Publication Date: 2011-08-17
    Description: Rocks from an ophiolite suite once on the seafloor were analyzed for rare earth elements (REE), Sc, Co, Na2O, Cr, Zn and FeO. Strontium isotope exchange noted in some of the lavas is attributed to basalt-seawater interaction; the Ce abundance in smectite- and zeolite-bearing lavas may also be due to prolonged exposure to seawater. The higher grades of metamorphic rock, however, show no variation from the usual flat or slightly light REE depleted profiles. Plutonic igneous rock, all light REE depleted, have total REE abundances varying by a factor of 100 between the dunites and diorites. In order of decreasing REE abundance are hornblende, clinopyroxene, plagioclase, orthopyroxene and olivine. Calculations of REE contents of liquids in equilibrium with early cumulative clinopyroxenes suggest that the parent to the stratiform sequence was more depleted in light REE than the parent to the lava pile.
    Keywords: GEOPHYSICS
    Type: Geochimica et Cosmochimica Acta; 41; Oct. 197
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  • 46
    Publication Date: 2011-08-17
    Keywords: GEOPHYSICS
    Type: . In the Space Sci., Vol. 2, No. 3; 19 p
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  • 47
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    Publication Date: 2011-08-17
    Description: In a computer simulation study of earthquakes a seismically active strike slip fault is represented by coupled mechanical blocks which are driven by a moving plate and which slide on a friction surface. Elastic forces and time independent friction are used to generate main shock events, while viscoelastic forces and time dependent friction add aftershock features. The study reveals that the size, length, and time and place of event occurrence are strongly influenced by the magnitude and degree of homogeneity in the elastic, viscous, and friction parameters of the fault region. For example, periodically reoccurring similar events are observed in simulations with near-homogeneous parameters along the fault, whereas seismic gaps are a common feature of simulations employing large variations in the fault parameters. The study also reveals correlations between strain energy release and fault length and average displacement and between main shock and aftershock displacements.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 82; Sept. 10
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  • 48
    Publication Date: 2011-08-17
    Description: The 1976 U.S. Standard Atmosphere, representing a mid-latitude atmosphere for moderate solar activity, is compared to earlier standards. For heights of 51 km and below, this standard is identical with its immediate predecessor, the 1962 U.S. Standard Atmosphere. When the density-height profile of each of five earlier model atmospheres is compared with that of the 1976 standard, an oscillation of this parameter around the currently accepted average value is observed, which is partly the result of true density changes related to the 11-year cycle of solar activity and partly the result of earlier uncertainties. The development of knowledge is also elucidated by comparing the temperature-height profiles of each of the important standards used during the preceding century. Number densities of each of six atmospheric species computed for the 1976 U.S. standard are compared over the height region of 0 to 1000 km.
    Keywords: GEOPHYSICS
    Type: Reviews of Geophysics and Space Physics; 15; Aug. 197
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  • 49
    Publication Date: 2011-08-17
    Description: Measurements of neutral nitrogen density from mass spectrometers on five satellites (AE-B, Ogo 6, San Marco 3, Aeros A, and AE-C) and neutral temperatures inferred from incoherent scatter measurements at four ground stations are combined to produce a model of thermospheric neutral temperatures and nitrogen densities similar to the Ogo 6 empirical model (Hedin et al., 1974). This global model is designated MSIS (mass spectrometer and incoherent scatter). The global average temperature, the annual temperature variation, lower bound density, and lower bound temperature are discussed. The data set covers the time period from the end of 1965 to mid-1975 and also a wide range of solar activities. Diurnal and semidiurnal variations in lower bound density and temperature are considered, as is magnetic activity.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 82; June 1
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  • 50
    Publication Date: 2011-08-17
    Description: Turbulence in planetary atmospheres and ionospheres causes changes in angles of refraction of radio waves used in occultation experiments. Atmospheric temperature and pressure profiles, and ionospheric electron concentration profiles, derived from radio occultation measurements of Doppler frequency contain errors due to such angular offsets. The lowest-order average errors are derived from a geometrical-optics treatment of the radio-wave phase advance caused by the addition of uniform turbulence to an initially homogeneous medium. It is concluded that the average profile errors are small and that precise Doppler frequency measurements at two or more wavelengths could be used to help determine characteristics of the turbulence, as well as accuracy limits and possible correction terms for the profiles. However, a more detailed study of both frequency and intensity characteristics in radio and optical occultation measurements of turbulent planetary atmospheres and ionospheres is required to realize the full potential of such measurements.
    Keywords: GEOPHYSICS
    Type: Astrophysical Journal; vol. 214
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  • 51
    Publication Date: 2011-08-17
    Description: Rocket observations of the lower ionosphere in the winter of 1971 at two locations show differences of electron density which are attributed to enhancements of nitric oxide and energetic electron fluxes precipitated into the mesosphere during the poststorm phase of a geomagnetic storm. Electron density distributions were observed above Wallops Island, Virginia, and Keweenaw, Michigan, larger values occurring at Keweenaw. Energetic electron fluxes were greater at Keweenaw (L = 3.9) than at Wallops Island (L = 2.5). While particle ionization was the dominant factor in establishing the electron density during one measurement at Keweenaw, particles were not present two days earlier, even though the electron density distribution was significantly larger than that observed at Wallops Island on both occasions. An accompanying ion composition profile measured at Keweenaw during the earlier flight showed NO(+) to be the dominant ion to 76 km, where the concentration of hydrated ions H3O(+).(H2O)n, exceeded that of NO(+).
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 82; May 1
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  • 52
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    Publication Date: 2011-08-17
    Description: Studies of the earth's magnetosphere have indicated that a large-scale electric field E plays a central role in its electrodynamics and in the flow and acceleration of charged particles there; while many observations relevant to E have accumulated, quite a few basic problems involving the origin and structure of this field remain unsolved. The ultimate source of E is presumably the flow of the solar wind past the earth, but the mechanism by which E arises is still unclear, and several independent sources may contribute to it, some of them being of a rather transient nature. This review attempts to sum up the main observed facts and theoretical concepts related to E.
    Keywords: GEOPHYSICS
    Type: Reviews of Geophysics and Space Physics; 15; May 1977
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  • 53
    Publication Date: 2011-08-17
    Description: A simple semiquantitative model is presented which allows analytic solutions of tidal and planetary wave propagation at thermospheric heights. This model is based on perturbation approximation and mode separation. The effects of viscosity and heat conduction are parameterized by Rayleigh friction and Newtonian cooling. Because of this simplicity, one gains a clear physical insight into basic features of atmospheric wave propagation. In particular, we discuss the meridional structures of pressure and horizontal wind (the solutions of Laplace's equation) and their modification due to dissipative effects at thermospheric heights. Furthermore, we solve the equations governing the height structure of the wave modes and arrive at a very simple asymptotic solution valid in the upper part of the thermosphere. That 'system transfer function' of the thermosphere allows one to estimate immediately the reaction of the thermospheric wave mode parameters such as pressure, temperature, and winds to an external heat source of arbitrary temporal and spatial distribution. Finally, the diffusion effects of the minor constituents due to the global wind circulation are discussed, and some results of numerical calculations are presented.
    Keywords: GEOPHYSICS
    Type: Reviews of Geophysics and Space Physics; 15; May 1977
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  • 54
    Publication Date: 2011-08-17
    Description: In situ measurements of variational electric fields at low latitudes, taken by OGO 6 satellite instruments, are analyzed. The observations are compared with other data on F region and spread-F structures. Conformity of the electric field fluctuations with the overall picture of low-latitude irregularities is examined empirically and theoretically, and candidate processes for generation of the observed irregularities are considered. Three distinct types of irregularities are delineated and compared.
    Keywords: GEOPHYSICS
    Type: Journal of Atmospheric and Terrestrial Physics; 39; Mar. 197
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  • 55
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    Publication Date: 2011-08-17
    Description: Practical applications of NASA space systems, science, and technology to the study of oceans and solid earth are discussed. Goals involving earth dynamics include earthquake hazard assessment and alleviation, and global surveying and mapping, while goals involving ocean dynamics include the determination of ocean currents and circulation, and the monitoring of ocean surface conditions. Satellites used to obtain data are described, and projects such as the study of open ocean tides and earth motion determination are reviewed, with consideration given to the techniques (e.g., laser ranging, satellite-to-satellite track) used in these studies. Several physical phenomena, the extent to which they presently can be measured, and possible future requirements for more accurate measurements are examined.
    Keywords: GEOPHYSICS
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  • 56
    Publication Date: 2011-08-17
    Description: The paper discusses techniques available for measuring polar motion, earth rotation and earth tides with laser tracking of satellites. In a discussion of future prospects, it is noted that when the Laser Geodynamics Satellite is launched, a network of laser stations is projected to be able to achieve better than 10 cm from each coordinate from less than one day of tracking.
    Keywords: GEOPHYSICS
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  • 57
    Publication Date: 2011-08-17
    Description: Two satellite-to-satellite tracking (sst) tests are described in detail: (1) the ATS-6/Geos-3 and (2) the ATS-6/Apollo-Soyuz experiment. The main purpose of these two experiments was to track via ATS-6 the Geos-3, as well as the Apollo-Soyuz and to use these tracking data to determine both of the orbits at the same time, each of the orbits alone, and to test the two sst links to study local gravity anomalies. A second purpose was to test communications, command and data transmission from the ground via ATS-6 to these spacecraft and back again to the ground.
    Keywords: GEOPHYSICS
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  • 58
    Publication Date: 2011-08-17
    Description: The paper reports the apparent generation of pulsating aurora by explosive releases of barium vapor near 250 km altitude. This effect occurred only when the explosions were in the path of precipitating electrons associated with the visible aurora. Each explosive charge was a standard 1.5 kg thermite mixture of Ba and CuO with an excess of Ba metal which was vaporized and dispersed by the thermite explosion. Traces of Sr, Na, and Li were added to some of the charges, and monitoring was achieved by ground-based spectrophotometric observations. On March 28, 1976, an increase in emission at 5577 A and at 4278 A was observed in association with the first two bursts, these emissions pulsating with roughly a 10 sec period for approximately 60 to 100 sec after the burst.
    Keywords: GEOPHYSICS
    Type: Nature; 267; May 12
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  • 59
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    Publication Date: 2011-08-17
    Description: The vertical profile of the horizontal wind in a strong equatorial electrojet is distinctly different from profiles observed previously at other times and locations. The zonal wind speed is small and varies slowly with altitude, whereas the meridional component manifests a cross-equatorial oscillation with altitude which may result from a unique interaction of the ionized and neutral motions.
    Keywords: GEOPHYSICS
    Type: Journal of Atmospheric and Terrestrial Physics; 39; Feb. 197
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  • 60
    Publication Date: 2011-08-17
    Description: Number-density data obtained at orbital 'crossover' points with the neutral-gas mass spectrometers aboard the Esro 4, Aeros A, AE-C, and Aeros B satellites are intercompared. All the mass spectrometers were designed to measure the ambient number densities of atomic oxygen, molecular nitrogen, helium, and argon. It is found that the agreement for N2 and O is satisfactory within the experimental errors and that the He measurements exhibit unexpectedly large discrepancies far outside the error range. Calibration and instrument sources of error are considered.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 82; Mar. 1
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  • 61
    Publication Date: 2011-08-17
    Description: The paper reports laser-induced fluorescence measurements of the initial product state distributions of CN(X2 Sigma +) produced during the photolysis of C2N2 at a wavelength of 160 nm. The parent molecules were photodissociated by an argon flash lamp, and saturated solutions of BBD in p-dioxane were used as a laser dye to produce radiation that excited CN radicals in the (upsilon-double-prime, N-prime) vibrational-rotational sublevels of the X state to the B-state sublevels. Spectral-line identification is discussed along with the observed rotational, electronic, and vibrational energy partitionings. The effect of added buffer gas (N2 or He) on the observed product state distributions is examined in order to monitor collisional energy transfer from CN(A2 Pi, upsilon = 0) to CN(X2 Sigma +, upsilon-double-prime = 4). It is found that both buffer gases produce population inversion between the upsilon-double-prime = 4 and upsilon-double-prime = 3 levels of the X state.
    Keywords: GEOPHYSICS
    Type: Journal of Chemical Physics; 66; Mar. 1
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  • 62
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    Publication Date: 2011-08-17
    Description: Magnetosphere substorm physics are updated in the monograph. Major topics include: (1) open magnetosphere and the auroral oval; (2) auroras and auroral particles; (3) plasma distribution in the magnetosphere; (4) magnetosphere responses to interplanetary disturbances; (5) magnetospheric substorms and magnetotail phenomena; (6) magnetospheric currents, plasma injection, plasmasphere disturbances; and (7) magnetospheric substorms and solar-terrestrial relations. Other topics covered include: open field lines and the open magnetosphere, field-aligned currents, auroral particles and atmospheric emissions, plasma mantle, plasma sheet, radiation belts, magnetic flux transfer to the magnetotail, polar cap phenomena, substorm parameters, thinning of the plasma sheet, auroral electrojets, diurnal variations and dawn-dusk asymmetry of particle distributions, and instabilities.
    Keywords: GEOPHYSICS
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  • 63
    Publication Date: 2011-08-17
    Description: A simple model of a static electric field with a component parallel to the magnetic field is proposed for calculating the electric field and current distributions at various altitudes when the horizontal distribution of the convection electric field is given at a certain altitude above the auroral ionosphere. The model is shown to be compatible with satellite observations of inverted-V electron precipitation structures and associated irregularities in the convection electric field.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science; 25; Jan. 197
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  • 64
    Publication Date: 2011-08-17
    Description: A Petrel rocket carrying a double cell rubidium magnetometer was launched from the Thumba Equatorial Rocket Launching Station during the early main phase of a magnetic storm. No ionospheric currents associated with the storm were observed, and the large field depression at the flight time must therefore be attributed to currents at higher altitudes. The equatorial enhancement of ionospheric magnetic storm currents, predicted on the basis of theory and earlier ground data, was not observed.
    Keywords: GEOPHYSICS
    Type: Journal of Atmospheric and Terrestrial Physics; 39; Jan. 197
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  • 65
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    Publication Date: 2011-08-17
    Description: In a previous paper, Fraser and Thorpe (1976) indicated that the average partial-coherence spectra for three summers and the average for three winters at a southern mid-latitude site had a dominant peak at a period of about six days. This peak in coherence between absorption and temperature is anomalous, and the present paper explains how some of the unexpected coherence features can be explained by the five-day wave described by Geisler and Dickinson (1976) and whose existence in the upper stratosphere was discussed by Rodgers (1976).
    Keywords: GEOPHYSICS
    Type: Journal of Atmospheric and Terrestrial Physics; 39; Jan. 197
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  • 66
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    Publication Date: 2011-08-17
    Description: Since their establishment in 1959 the orbits of Vanguard 3 (1959-7A) and the Vanguard 2 rocket (1959-2B) have been slowly contracting through at least five strong resonances of eleventh order. Tracking with Baker-Nunn cameras and the U.S. Navy space surveillance (radio interferometer) system over a 14-year period has revealed resonant fluctuations on them of up to 0.035 deg in inclination (peak to peak). Six geopotential terms (lumped coefficients) of eleventh order and three of twenty-second order have been measured by using orbit inclinations derived from this tracking record. The terms of eleventh order are significantly smaller than is predicted by Kaula's rule. (The lumped coefficients are sensitive to geopotential effects as high as thirty-seventh degree.) These observed terms are compatible with a recent 27-satellite geopotential solution (GEM 7) whose formal coefficent errors are increased by a factor of 3.3.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 82; Feb. 10
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  • 67
    Publication Date: 2011-08-17
    Description: A refinement has been obtained in the earth's gravitational field by using satellite and surface data. In addition to a more complete treatment of data previously employed on 27 satellites, the new satellite solution Gem 7 (Goddard Earth Model 7) includes 64,000 laser measurements taken on seven satellites. Gem 7, containing 400 harmonic terms, is complete through degree and order 16. The companion solution Gem 8 combines the same satellite data as Gem 7 with surface gravimetry over 39% of the earth. Gem 8 is complete to degree and order 25. Extensive tests on data independent of the solution show that the undulations of the geoidal surface computed by Gem 7 have an accuracy of about 2.5 m (rms). The overall accuracy of the geoid calculated by Gem 8 is estimated to be about 4 m (rms). The new combination solution is the first to show signs of 'convection rolls' in the upper mantle below the Pacific Ocean.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 82; Feb. 10
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  • 68
    Publication Date: 2011-08-17
    Description: Two mechanisms have been proposed for solar wind particle injection at the dayside magnetospheric cusps: magnetic merging and cross-field diffusion. These two mechanisms are experimentally distinguishable in that they produce different latitudinal distributions of particles penetrating to the low-altitude cusp. An examination of proton and electron measurements obtained by the AE-C satellite in the low-altitude dayside cusp reveals evidence of both types of injection processes. A majority of the injection events, especially the more intense fluxes, are best explained by a merging injection model in which cusp particles are confined to the poleward side of the last closed field line and have a characteristic energy that decreases with increasing latitudinal distance from the last closed field line. Less frequent and less intense injection events are better explained in terms of a diffusive injection of cusp particles onto closed dayside field lines with a characteristic energy that increases with increasing latitudinal distance from the last closed field line. Although diffusion appears to be quantitatively less important than merging in terms of the instantaneous particle injection rate, cross-field diffusion nevertheless appears to proceed at an unexpectedly fast rate, possibly exceeding the Bohm diffusion limit.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 82; Feb. 1
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  • 69
    Publication Date: 2011-08-17
    Description: Variation in the eddy diffusion coefficient constitutes a momentum source. This variation near the turbopause affects both the composition and the wind and temperature fields of the thermosphere. Two types of calculations are carried out, for horizontal winds considered self-consistently in a three-dimensional dynamic model and horizontal winds artificially suppressed to simulate a one-dimensional model. Momentum transfer associated with variations in eddy diffusion coefficients represents the source function in the analysis presented. It is shown that for long-term variations in the thermosphere, the compositional dependence on variations in eddy diffusion coefficients can be entirely different in one and three dimensional models with horizontal winds included. Horizontal winds can greatly reduce the effects of eddy diffusion in general and the ratio between He and O amplitudes in particular.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters; 4; Jan. 197
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  • 70
    Publication Date: 2011-08-17
    Description: The infrared spectral reflectance at near normal incidence has been measured for 3.2 M, 2.4 M, and 1.6 M solutions of ammonium sulfate, an aerosol abundant in the stratosphere and also present in the troposphere. Kramers-Kronig analysis was used to determine values of the refractive and absorption indices from the measured spectral reflectance. A synthetic spectrum of crystalline ammonium sulfate was obtained by extrapolation of the absorption index obtained for the solution to the absorber number densities of the NH4 and SO4 ions characteristic of the crystal.
    Keywords: GEOPHYSICS
    Type: Optical Society of America; vol. 67
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  • 71
    Publication Date: 2011-08-16
    Description: The derivation of exospheric temperature from satellite drag measurements is based on an assumption of invariant conditions of the neutral atmosphere at 120 km. Since it has been established that atomic oxygen, which is usually the major neutral constituent in the region of drag measurements, is subject to considerable variability with season, latitude, and solar and geomagnetic activity in the altitude region of 120 km, its value as an indicator of exospheric temperature is questionable. Ogo 6 neutral mass spectrometer measurements revealed that molecular nitrogen is a better indicator of exospheric temperature, since it is not subject to changes caused by eddy mixing and is therefore relatively less variable near the turbopause. However, theoretical arguments show that argon, even though it is a minor constituent, is relatively less variable with respect to changes in eddy diffusion coefficient and hence a better indicator of exospheric temperature than O and N2. In this paper the relative merits of these gases for deriving exospheric temperature are investigated by using observational data from the Aeros-A Nate experiment.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 80; Sept. 1
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  • 72
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    Publication Date: 2011-08-16
    Description: A strong thirteenth-order resonance has been observed in an analysis which is based on U.S. Navy tracking data regarding the slowly decaying orbit of a Diademe 2 fragment. The exact commensurability for the orbit occurred in late 1973. The major changes due to the resonance were over by late 1974. Approaches for a significant improvement of thirteenth-order geopotential terms are discussed.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 80; Sept. 10
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  • 73
    Publication Date: 2011-08-16
    Description: The possibility of using airglow techniques for estimating the electron density and height of the F layer is studied on the basis of a simple relationship between the height of the F2 peak and the column emission rates of the O I 6300 A and O I 1356 A lines. The feasibility of this approach is confirmed by a numerical calculation of F2 peak heights and electron densities from simultaneous measurements of O I 6300 A and O I 1356 A obtained with earth-facing photometers carried by the Ogo 4 satellite. Good agreement is established with the F2 peak heights estimates from top-side and bottom-side ionospheric sounding.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 80; June 1
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  • 74
    Publication Date: 2011-08-16
    Description: The results of the Neutral Atmospheric Composition Experiment (Nace) on the Italian San Marco 3 satellite are analyzed. The analysis provides a comprehensive description of the daily variations in the densities of O, N2, Ar, and He in composition of the lower thermosphere, and also indicates that transport processes (possibly occurring elsewhere in the atmosphere) play an important part in the daily variation of the thermospheric composition at altitudes between 220 and 250 km.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 80; June 1
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  • 75
    Publication Date: 2011-08-16
    Description: Intensities of auroral hiss generated by the Cerenkov radiation process by electrons in the lower magnetosphere are calculated with respect to a realistic model of the earth's magnetosphere. In this calculation, the magnetic field is expressed by the Mead-Fairfield Model (1975), and a static model of the iono-magnetospheric plasma distribution is constructed with data accumulated by recent satellites (Alouette-I, -II, ISIS-I, OGO-4, -6 and Explorer 22). The energy range of hiss producing electrons and the frequency range of the calculated VLF are 100-200 keV, and 2-200 kHz, respectively. The higher rate of hiss occurrence in the daytime side, particularly in the soft electron precipitation zone in the morning sector, and the lesser occurrence of auroral hiss in night-time sectors must be due to the local time dependence of the energy spectra of precipitating electrons rather than the difference in the geomagnetic field and in the geoplasma distributions.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science; 23; May 1975
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  • 76
    Publication Date: 2011-08-16
    Description: An investigation conducted by Backus (1970) regarding the possible existence of two harmonic functions of certain characteristics in three-dimensional space is considered. The derivation of a model of the main geomagnetic field from scalar data is discussed along with a numerical simulation study. It is found that experimental discrepancies between vector field observations and the predictions of the model may have a mathematical origin, related to the work of Backus.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 80; May 1
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  • 77
    Publication Date: 2011-08-16
    Description: A simple two-ion model was employed to evaluate the ionospheric effects of various nocturnal ionization sources. The model was used to calculate the decay of the electron number density at 90 km with and without illumination by Scorpius XR-1 X rays. Reflection parameters for the determination of the effect of cosmic x-ray sources on radio wave propagation were also obtained. The results obtained in the investigation do not support the proposal made by Anathakrishnan and Ramanathan (1969) that the X-ray source in Scorpius XR-1 affects the nighttime lower ionosphere of the earth.
    Keywords: GEOPHYSICS
    Type: Journal of Atmospheric and Terrestrial Physics; 37; May 1975
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  • 78
    Publication Date: 2011-08-16
    Description: The Ariel 4 satellite was designed to study wave-particle phenomena in the magnetosphere by measuring the electromagnetic wave fields over a wide frequency range and the fluxes and pitch angle distributions of energetic particles. We describe here the results of a preliminary study of the various v.l.f./e.l.f. electromagnetic wave phenomena which are observed. These include man-made signals from v.l.f. transmitters, impulsive noise originating in thunderstorms and emissions arising from magnetospheric energetic charged particles.
    Keywords: GEOPHYSICS
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  • 79
    Publication Date: 2011-08-16
    Description: Fifteenth-order commensurability of the orbit of TETR-3 (1971-83B) is studied. The study is designed to obtain good discrimination of 15th-order resonances through a better range of inclinations. The first low inclination orbit, 33 deg, is used for this purpose; it is very sensitive to the high degree terms which were rather poorly represented by previously analyzed orbits.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science; 23; Mar. 197
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  • 80
    Publication Date: 2011-08-16
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 80; Apr. 1
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  • 81
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    Publication Date: 2011-08-16
    Description: An investigation regarding the occurrence of Si ions is conducted, taking into account an unusual metal ion structure observed during a meteor shower event. Loss processes involving silicon oxides are considered in connection with a study of the reasons for the unique Si(+) distribution found. It is suggested that below 100 km Si(+) is rapidly depleted by two- and three-body reactions with molecular oxygen, forming SiO2(+) which then recombines.
    Keywords: GEOPHYSICS
    Type: Radio Science; 10; Mar. 197
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  • 82
    Publication Date: 2011-08-16
    Keywords: GEOPHYSICS
    Type: Journal of Atmospheric and Terrestrial Physics; 37; Apr. 197
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  • 83
    Publication Date: 2011-08-16
    Description: Regions of enhanced cold plasma, isolated from the main plasmasphere along the Explorer 45 (53-A) orbit in the equatorial plane, have been detected by using the sheath-induced potentials seen by the electric field experiment. The occurrence of these regions has a strong correlation with negative enhancements of Dst, and their locations are primarily in the noon-dusk quadrant. The data support the concept that changes in large-scale convection play a dominant role in the formation of these regions. Plasma tails that are predicted from enhancements of large-scale convection electric fields in general define where these regions may be found. More localized processes are necessary to account for the exact configuration and structure seen in these regions and may eventually result in detachment from the main plasmasphere.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 80; Mar. 1
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  • 84
    Publication Date: 2011-08-16
    Description: Light ion trough measurements near midnight made by the Bennett RF ion mass spectrometer on Ogo 4 operating in the high-resolution mode reveal the existence of irregular structure on the low-latitude side of the mid-latitude trough. By using two different relations between the equatorial convection electric field, assumed to be spatially invariant and directed from dawn to dusk, and Kp, a model development was made of the outer plasmasphere. The model calculations produced multiple plasma tails that compare favorably with the observed thermal proton irregularities. The model development produces an outer plasmasphere boundary location that varies similarly to the observed minimum density point of the light ion trough. However, the measurements are not extensive enough to yield conclusive proof that one of the electric field models is better than the other.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 80; Mar. 1
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  • 85
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    In:  Other Sources
    Publication Date: 2011-08-16
    Description: Ion effects are often observed on topside-sounder-stimulated electron plasma wave phenomena and the present study is concerned with the spur effect relative to electron plasma resonance. A spur appears after a time delay corresponding to the proton gyroperiod and is observed mainly on the resonances at the electron plasma frequency and the harmonics of the electron cyclotron frequency. Proton spurs occur at the harmonic resonances only, when the electron plasma waves associated with these resonances are susceptible to the Harris instability and when the electromagnetic wave can be initiated by the sounder pulse. This instability results from a sounder-stimulated anisotropic electron velocity distribution. The observations suggest that energy is fed into the harmonics of the longitudinal plasma wave from the electromagnetic wave through wave-mode coupling. The observations were made during eight passes of the Alouette-2 satellite.
    Keywords: GEOPHYSICS
    Type: Radio Science; 10; Feb. 197
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  • 86
    Publication Date: 2011-08-16
    Description: Using 1.55 cm observations of the earth made by the Electrically Scanned Microwave Radiometer (ESMR) experiment on Nimbus 5, the appearance of the earth from Venus is simulated. A single antenna unable to resolve the earth's disk would give a time-averaged disk temperature of 183 K. In one rotation, the disk temperature would vary from 194 K to 172 K. During the 1973 inferior conjunction, a radio telescope with 1 arc sec resolution would resolve most of the major surface features of the earth.
    Keywords: GEOPHYSICS
    Type: Icarus; 24; Feb. 197
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  • 87
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    In:  Other Sources
    Publication Date: 2011-08-16
    Description: A subset of Pogo satellite magnetometer data has been formed that is suitable for analysis of crustal magnetic anomalies. Through the use of a thirteenth-order field model fit to these data, magnetic residuals have been calculated over the world to latitude limits of plus or minus 50 deg. These residuals, averaged over 1-degree latitude-longitude blocks, represent a detailed global magnetic anomaly map derived solely from satellite data. The occurrence of these anomalies on all individual satellite passes independent of local time and their decay as altitude increases imply a definite internal origin. Their wavelength structure and their correlation with known tectonic features further suggest that these anomalies are primarily of geologic origin and have their sources in the lithosphere.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 80; Feb. 10
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  • 88
    Publication Date: 2011-08-16
    Description: The Hamiltonian for a dipole field is developed, and the result is expressed by an analytic approximation accurate to within about 1%. This allows extension of results derived for equatorial particles to particles with arbitrary pitch angles; in particular, it makes available even in the presence of electric fields orthogonal to the magnetic field a function K that is preserved by the bounce-averaged motion. This function provides at once the equations of drift paths in (alpha, beta) or of their projections onto the equatorial plane; the derivation of a pacing function that times the progress of particles along such drift paths is also described.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 80; Feb. 1
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  • 89
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    In:  Other Sources
    Publication Date: 2011-08-16
    Description: In a time-independent model of the magnetosphere including a dipole magnetic field, a convection electric field (deduced from polar orbit observations), and an electric field due to the earth's rotation, the motion of a proton in the equatorial plane is analyzed. By means of the Hamiltonian of the motion, three regimes of motion are identified. A method is then developed for determining for any given observation point which arrival energies correspond to trapped particles and which represent 'open' trajectories.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 80; Feb. 1
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  • 90
    Publication Date: 2011-08-16
    Description: The model is derived by making least squares fits to magnetic field measurements from four Imp satellites. It includes four sets of coefficients, representing different degrees of magnetic disturbance as determined by the range of Kp values. The data are fit to a power series expansion in the solar magnetic coordinates and the solar wind-dipole tilt angle, and thus the effects of seasonal north-south asymmetries are contained. The expansion is divergence-free, but unlike the usual scalar potential expansion, the model contains a nonzero curl representing currents distributed within the magnetosphere. The latitude at the earth separating open polar cap field lines from field lines closing on the day side is about 5 deg lower than that determined by previous theoretically derived models. At times of high Kp, additional high-latitude field lines extend back into the tail. Near solstice, the separation latitude can be as low as 75 deg in the winter hemisphere. The average northward component of the external field is much smaller than that predicted by theoretical models; this finding indicates the important effects of distributed currents in the magnetosphere.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 80; Feb. 1
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  • 91
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    In:  Other Sources
    Publication Date: 2011-08-16
    Description: The latitudinal characteristics of He+ in the equatorial region are compared with those of O+ and H+. These ions, in different altitude regions, exhibit certain features which are characteristics of the ionospheric geomagnetic anomaly. It is shown that the latitudinal distributions of these ions are related to their vertical distribution at the equator via their respective scale heights and the geomagnetic dipole geometry. To a first order, the positions of the latitudinal maxima of a given ion may be related to its peak altitude at the equator by a proposed expression.
    Keywords: GEOPHYSICS
    Type: Journal of Atmospheric and Terrestrial Physics; 37; Feb. 197
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  • 92
    Publication Date: 2011-08-16
    Description: A possible mechanism for the action of solar radiation on the motion of the upper atmosphere is considered that includes the time dependent interplanetary field contour line and its effect on zonal wind velocity. A strong correlation is reported between this induction mechanism and those indices of solar activity that characterize the magnetic fields of the solar plasma.
    Keywords: GEOPHYSICS
    Type: Phys. of the Sea and Atmosphere NASA-TT-F-16225; p 17-21
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  • 93
    Publication Date: 2011-08-16
    Description: A solution of the lidar equation is given with the aim of determining the attenuation coefficient of the atmosphere under conditions of the existence of a relation between it and the effective backscatter area. The errors of determining the attenuation coefficient from measurements of the echo signal power are analyzed. A proposed method of determining that coefficient by sounding with variable pulse lengths is examined.
    Keywords: GEOPHYSICS
    Type: Radar Meteorology (NASA-TT-F-14797); p 134-143
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  • 94
    Publication Date: 2011-08-16
    Description: The geomagnetic fields of the past geological epochs are studied on the basis of observations on the rock residual magnetization. This paper evaluates the shifts in the isotopic composition of the same elements in the rocks affected by cosmic rays. The possibility of using the shifts in the isotopic composition for revealing geomagnetic field inversions is discussed. Geomagnetic field inversion periods traced by the rock residual magnetization are in good agreement with the periods of the greatest qualitative changes in the animal world throughout the last 500 million years.
    Keywords: GEOPHYSICS
    Type: Cosmic Rays (; p 164-169
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  • 95
    Publication Date: 2011-08-16
    Description: The calculation results of L, B-coordinates for different years from 1957 to 1967 are given. Periodic calculations of the geomagnetic coordinates for different epochs are considered to be very urgent.
    Keywords: GEOPHYSICS
    Type: Cosmic Rays (; p 159-163
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  • 96
    Publication Date: 2011-08-16
    Description: Current systems formed during magnetic disturbances cause threshold energy variations of cosmic ray particles. The latter, in turn, are a source of electron production in the terrestrial atmosphere. The paper gives the calculations of the electron production rate with the count of threshold variations during magnetic disturbances.
    Keywords: GEOPHYSICS
    Type: Cosmic Rays (; p 154-158
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  • 97
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    In:  Other Sources
    Publication Date: 2011-08-16
    Description: The inflow of charges of small ions, formed by cosmic rays, into thunderstorm cells is estimated on the basis of rocket measurements of ionic concentrations below 90 km. Out of the two processes that form the thunderstorm charge (generation and separation of charges), the former is supposed to be caused by cosmic rays, and the nature of separation is assumed to be the same as in other thunderstorm theories.
    Keywords: GEOPHYSICS
    Type: Cosmic Rays (; p 145-147
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  • 98
    Publication Date: 2011-08-16
    Description: The dependence of the atmospheric conductivity upon the cosmic ray intensity, the possibility of charge generation in thunderstorms by cosmic rays, the dependence of the troposphere electricity on the stratosphere, the relationship between the unitary variation of the earth's electric field intensity and that of cosmic ray intensity (daily, yearly and 11-year latitudinal dependence of both values), deny first, the exceptional role of the tropospheric processes in maintaining the terrestrial charge and unitary variation, and, second, compel one to consider the cause mentioned above to be the result of the influence of cosmic rays.
    Keywords: GEOPHYSICS
    Type: Cosmic Rays (; p 148-153
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  • 99
    Publication Date: 2011-08-16
    Description: On the basis of over 15 rocket measurements of ionic concentrations below 80 km, the height, daily and latitudinal dependences between positive ionic concentrations and cosmic ray intensity below 60 km as well as between ionic concentrations and corpuscular streams within the 60-80 km altitude range are compared. It is shown that ionic concentration and cosmic ray intensity below 60 km at night are likely to be interrelated, in conformity with Chapman's theory of the simple layer. In daytime, all phenomena are aggravated by photodetachment and ion exchange reactions with the participation of ozone. Between 60-80 km, besides ordinary cosmic rays, there must exist an additional corpuscular stream.
    Keywords: GEOPHYSICS
    Type: Cosmic Rays (; p 142-144
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  • 100
    Publication Date: 2011-08-16
    Description: Observations are presented on the variations of extended air shower intensity with an average power of 1.4 x 10,000 and 1.4 x 100,000 particles at sea level. The effect of disintegrating particles and the essential role of cascades formed above the lower third of the atmosphere are examined. However, the authors failed to discover anisotropy of initial particles with an energy of 10 to the 14th power to 10 to the 15th power eV with an accuracy of up to 0.1%.
    Keywords: GEOPHYSICS
    Type: Cosmic Rays (; p 133-137
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