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- Issue 12 Pages 721-
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Volume 19 (1967)
- Issue 4 Pages 261-
- Issue 3 Pages 157-
- Issue 2 Pages 81-
- Issue 1 Pages 1-
Volume 19, Issue 1
Displaying 1-8 of 8 articles from this issue
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Henry R. RADOSKI1967 Volume 19 Issue 1 Pages 1-5
Published: April 25, 1967
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSThe longitude independent wave equation for the poloidal or isotropic magnetohydrodynamic resonances of a plasma magnetized by a dipole field is solved under the assumption of an Alfvén velocity increasing linearly with radial distance and retaining the latitude dependence of the magnetic field. Such a radial dependence is the only case in which the equation is separable in spherical coordinates and the solution possesses several advantages: the radial functions are particularly simple, the eigenfrequencies are derivable from an algebraic equation, and the contribution of the magnetic field's polar angle dependence can be clearly obserued.View full abstractDownload PDF (455K) -
N. S. WADEHRA, B. A. P. TANTRY1967 Volume 19 Issue 1 Pages 7-13
Published: April 25, 1967
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSQuasi-sinusoidal waveforms of distant atmospherics recorded at night were Fourier analysed using an electronic digital computer to yield the amplitude spectra in the VLF range of 1-20kc/s. The relative values of attenuation coefficients, calculated from amplitude spectra have been compared with the experimental results of Hepburn and Wait's theoretical attenuation curves. The attenuation is found to be maximum at 4kc/s and minimum in the frequency range 7-12kc/s, and is in general agreement with results of Croom (1964). The attenuation is also found to increase in 12-20kc/s range, as earlier observed by Taylor and Lange (1958) and Obayashi et al (1959), and this can be explained partly by the waveguide theory (Wait, 1962). The variation of peak frequency and band width of the received atmospherics with propagation distance has also been discussed.View full abstractDownload PDF (690K) -
A. ONWUMECHILLI, P. O. OGBUEHI1967 Volume 19 Issue 1 Pages 15-22
Published: April 25, 1967
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSA method is described for obtaining the parameters of the equatorial electrojet on individual days using a new model of the electrojet and data from a few observatories close to the same longitude. Preliminary results of applying this to the equatorial electrojet in India are given. The electrojet seems to be wider in Peru and narrower in Nigeria than in India. The intensity of the electrojet is negatively correlated with the intensity of the world-wide Sq current. The fluctuations in electrojet parameters in September 1958 are given.View full abstractDownload PDF (637K) -
Jagdish C. GUPTA1967 Volume 19 Issue 1 Pages 23-26
Published: April 25, 1967
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSIt is shown that the time of ascent and descent of the S-current intensity during an “intense” sunspot cycle is nearly 4 and 7 years, respectively. On the other hand, in a “weak” sunspot cycle the intensity rises to maximum and falls to minimum in about equal periods. Analogous conditions hold true in the case of the 10.7cm radio noise flux. These results are in agreement with the Schmidt's work on sunspot numbers.View full abstractDownload PDF (379K) -
Hiroshi KAMIYAMA1967 Volume 19 Issue 1 Pages 27-47
Published: April 25, 1967
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSIn this paper characteristic features of the synthetic effect of a flux of precipitating mono-energy electrons are studied for the representative incident energies. The maximum rate of impact ionization produced by an electron flux of 2π×107cm-2sec-1 is found to be about 1.7×103cm-3sec-1 at about the 116km-level for the incident electron energy E0=10kev, and about 2.3×104cm-3sec-1 at about the 88km-level for E0=100kev. On the other hand, the maximum rate of photoionization produced through the absorption of bremsstrahlung x-rays caused by the same flux is about 3.6×10-2cm-3sec-1 at about 97km for E0=10kev, and about 1.9×101cm-3sec-1 at about 45km for E0=100kev. The consequent maximum electron density is estimated to be about 8.4×104cm-3 at about 117km for E0=10kev, and about 3.0×105cm-3 at about 90km for E0=100kev. In the latter case where E0=100kev, the electron density of the order of 103cm-3 extends to a level as low as 65km. The associated auroral luminosity is estimated to be 0.21kR (kilo-rayleighs) at λ3914A, 0.14kR at λ5577A, and 0.17kR at λ6300A for E0=10kev; and 1.4kR at λ3914A, 0.15kR at λ5577A, and 0.046kR at λ6300A for E0=100kev. Estimates are also made of the total effects of a flux of precipitating electrons having an energy spectrum expressed as 2πi0exp (-E0/β) at the top of the atmosphere. With i0=108cm-2sec-1kev-1ster-1 and β=5kev, the maximum electron density is found to be about 3.2×105cm-3 at about 114km. It is suggested that the electron flux of 27π×4.5×104cm-2sec-1 having such an energy spectrum would be required in order to explain the observed electron density in the nighttime E layer at middle latitudes, as due to the influx of energetic electrons.View full abstractDownload PDF (1919K) -
An Application of Oblate Spheroidal Harmonic Functions to the Determination of Geomagnetic potentialD. E. WINCH1967 Volume 19 Issue 1 Pages 49-61
Published: April 25, 1967
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSThe general theory of harmonic analysis of the potential of the Earth's main magnetic field is presented in terms of oblate spheroidal harmonic functions, treating the figure of the Earth as an oblate spheroid. It is a modification of the theory given originally by Schmidt, but removes the requirement of 48 multiplicative constants pnm and qnm. The theory is applied to Schmidt's data for epoch 1885 and for comparison the same data has been analyzed using sperical harmonic functions and treating the Earth as a sphere. Both analyses have been done both considering and ignoring the external field. Of the 48 coefficients for the external field, 18 are found to be significant at the 95 per cent confidence level and the magnitude of the external component of g10 is found to be significantly reduced from 226γ for a spherical Earth to 139γ for an oblate Earth. This reduction is shown to be theoretically necessary, and application of the theory to spherical harmonic coefficients for epoch 1965, shows that the magnitude of the external component of g10 is reduced from 82γ to 0γ.View full abstractDownload PDF (1012K) -
N. D. WATKINS1967 Volume 19 Issue 1 Pages 63-76
Published: April 25, 1967
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSPart of a section of Miocene lavas in southeastern Oregon has been observed to possess natural remanent magnetism (NRM) superficially consistent, in both direction and intensity of magnetization, with the existence of a geomagnetic polarity transition contemporaneous with initial cooling of the lavas. Investigation of unstable magnetic components and other appropriate properties reveals, however, that the critical NRM is a function of petrological and not geomagnetic field properties. The occurrence of maghemite and unoxidized ilmenite lamellae in titanomagnetite are strongly associated with the systematic magnetic instability. The creation of high magnetic stability in the lavas concerned, by natural secondary oxidizing processes, could possibly result in convincing but totally misleading evidence for a Miocene geomagnetic polarity transition.View full abstractDownload PDF (1299K) -
H. Kinoshita, T. Nagata1967 Volume 19 Issue 1 Pages 77-79
Published: April 25, 1967
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSDownload PDF (251K)
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