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  • 11
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    Ring current proton decay by charge exchange (1976)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Explorer 45 (S3-A) measurements were made during the recovery phase of the moderate magnetic storm of February 24, 1972, in which a symmetric ring current had developed and effects due to asymmetric ring current losses could be eliminated. It was found that after the initial rapid decay of the proton flux, which is a consequence of the dissipation of the asymmetric ring current, the equatorially mirroring protons in the energy range 5-30 keV decayed throughout the L value range of 3.5-5.0 at the charge exchange decay rate calculated by Liemohn (1961). After several days of decay, the proton fluxes reached a lower limit where an apparent equilibrium was maintained, between weak particle source mechanisms and the loss mechanisms, until fresh protons were injected into the ring current region during substorms. While other proton loss mechanisms may also be operating, the results indicate that charge exchange is more than sufficient as a particle loss mechanism for the storm time proton ring current decay.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 81; June 1
    Format: text
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  • 12
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    Temperate zone sporadic-E maps /f/0/E/s/ greater than 7 MHz/ (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Three maps are presented of f(0) sporadic-E greater than 7 MHz for temperate zones. During map preparation it was assumed that: (1) the geographical area would be between plus and minus 60 deg geomagnetic latitude, excluding the equatorial zone, (2) the maps would be for f(0) sporadic-E greater than 7 MHz, (3) sunspot cycle variation would be ignored, (4) one map would represent the peak sporadic-E period with a discontinuity at the geographic equator, (5) one map would represent non-peak periods with a discontinuity at the geographic equator, (6) one map would represent all twelve months with no equatorial discontinuity, and (7) previously determined coefficients for median and upper decile f(0) sporadic-E would be extrapolated to 7 MHz.
    Keywords: GEOPHYSICS
    Type: Radio Science; 13; May-June
    Format: text
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  • 13
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    Motions of charged particles in the magnetosphere under the influence of a time-varying large scale convection electric field (1979)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The motions of charged particles under the influence of the geomagnetic and electric fields are quite complex in the region of the inner magnetosphere. The Volland-Stern type large-scale convection electric field with gamma = 2 has been used successfully to predict both the plasmapause location and particle enhancements determined from Explorer 45 (S3-A) measurements. Recently introduced into the trajectory calculations of Ejiri et al. (1978) is a time dependence in this electric field based on the variation in Kp for actual magnetic storm conditions. The particle trajectories are computed as they change in this time-varying electric field. Several storm fronts of particles of different magnetic moments are allowed to be injected into the inner magnetosphere from L = 10 in the equatorial plane. The motions of these fronts are presented in a movie format. The local time of injection, the particle magnetic moments and the subsequent temporal history of the magnetospheric electric field play important roles in determining whether the injected particles are trapped within the ring current region or whether they are convected to regions outside the inner magnetosphere.
    Keywords: GEOPHYSICS
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  • 14
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    Atmospheric implications of studies of Central American volcanic eruption clouds (1979)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 84; Nov. 20
    Format: text
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  • 15
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    The convection electric field model for the magnetosphere based on Explorer 45 observations (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Large-scale electric fields in the magnetosphere, represented by the scalar potentials of corotation and convection fields, are examined in order to interpret both plasmapause positions at different local times and energetic particle penetrations inside the plasmapause observed by the Explorer 45 (S3-A) dc E field measurements and particle detectors. The Volland-Stern type convection electric field is assumed. A uniform dawn-dusk convection electric field which corresponds to an exponent (gamma) of unity is not consistent with the observational data, but the Volland-Stern model with gamma = 2 more likely represents the convection electric field during the hours of electric field increases during magnetic activity. In the time-independent case, the shape of the plasmapause does not depend on the intensity of the convection electric field, so that by using two plasmapause distances at different local times along the S3 outbound and inbound orbits the shape factor gamma of the convection field could be determined. The average value of gamma for 42 cases was found to be 2.4.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 83; Oct. 1
    Format: text
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  • 16
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    Ring current electron trajectories associated with VLF emissions (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The reported investigation had the objective to explain features of the ring current electron enhancements which are associated with the simultaneously observed VLF emissions during geomagnetic storms and substorms. Two examples of the electron intensity enhancements observed by Explorer 45 are presented, and the calculations of the electron trajectories injected from the geomagnetic tail into the nightside of the plasmasphere are discussed. These calculations are performed by modifying the computer program developed by Ejiri (1978) to explain the so-called nose events of the ring current protons. The presented calculation demonstrates the soundness of the models of the convective electric field and the static magnetic field.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 83; Sept. 1
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  • 17
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    Plasma wave turbulence at the magnetopause - Observations from ISEE 1 and 2 (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: An investigation of plasma wave electric and magnetic fields in the vicinity of the magnetopause using measurements from the ISEE 1 and 2 spacecraft is presented. Strong electric and magnetic field turbulence is often observed at the magnetopause; the electric field spectrum of this turbulence extends from less than a few hertz to over 100 kHz, and the magnetic field from a few hertz to about 1 kHz. Similar turbulence spectra are observed in association with flux transfer events and possible 'inclusions' of boundary layer plasma in the magnetosphere. Two possible plasma instabilities, the electrostatic ion-cyclotron and the lower-hybrid-drift instability, should explain the broad-band electric field turbulence; the narrow-band electrostatic emissions near the local electron plasma frequency are believed to be plasma oscillations or electrostatic waves near the upper-hybrid-resonance frequency.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 84; Dec. 1
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  • 18
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    Initial results from the ISEE-1 and -2 plasma wave investigation (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: A survey of initial results from the plasma-wave investigation on the ISEE 1 and 2 spacecraft is presented. The plasma-wave instruments employed are designed to provide measurements of the electric and magnetic fields of plasma waves over the frequency range from about 5 Hz to 300 kHz. Several representative satellite passes are analyzed in detail and discussed. The results considered are shown to demonstrate the very high-quality data being obtained with the instruments and to illustrate the wide range of magnetospheric plasma-physics problems that can be treated with the ISEE spacecraft. Comparisons of plasma-wave spectra between the two spacecraft are performed which indicate the great advantages of using two spacecraft in similar orbits to unravel the complex spatial and temporal variations that occur in the magnetosphere.
    Keywords: GEOPHYSICS
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  • 19
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    Midlatitude sporadic-E layers (1976)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The partially transparent echo from midlatitude sporadic E layers was recorded by ionosondes between the blanketing frequency and the maximum frequency. The theory that the midlatitude sporadic E layers are not uniform in the horizontal plane but contain localized regions of high electron density was evaluated using data obtained by incoherent scatter radar and found to provide a satisfactory explanation. The main features of midlatitude sporadic E layers are consistent with the convergence of metallic ions as described by the wind shear theory applied to gravity waves and tides. The interference of gravity waves with other gravity waves and tides can be recognized in the altitudes of occurrence and the structure of the layers. Small scale horizontal irregularities are attributed in some cases to critical level effects and in others to fluid instabilities. The convergence of a meteor trail can, under some circumstances, account for localized enhancement of the electron density in the layer.
    Keywords: GEOPHYSICS
    Type: NASA-CR-153057 , REPT-76 , IULU-ENG-76-2507 , (ISSN 0568-0581)
    Format: application/pdf
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  • 20
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    Reflection of radio waves by sporadic-E layers (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: A full-wave analysis of the reflection coefficient is developed and applied to electron-density profiles of midlatitude sporadic-E layers observed by rocket-borne probes. It is shown that partial reflection from the large electron-density gradients at the upper and lower boundaries of sporadic-E layers does not account for the partial transparency observed by ionosondes.
    Keywords: GEOPHYSICS
    Type: Journal of Atmospheric and Terrestrial Physics; 39; Aug. 197
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