Journal of geomagnetism and geoelectricity
Online ISSN : 2185-5765
Print ISSN : 0022-1392
ISSN-L : 0022-1392
Search
Advanced search
OR
Browse
Search
Volume 29, Issue 5
Displaying 1-5 of 5 articles from this issue
Show all abstracts
    • |<
    • <
    • 1
    • >
    • >|
  • Influence of the Dipole Tilt Angle on the Development of Auroral Electrojets
    Takao AOKI
    1977 Volume 29 Issue 5 Pages 441-453
    Published: 1977
    Released on J-STAGE: March 12, 2010
    DOIhttps://doi.org/10.5636/jgg.29.441
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Influence of the tilt angle of the geomagnetic dipole, χ, on the development of auroral electrojets was investigated paying attention to the relation with solar wind parameters. Indices AU and AL were used as the measures of the intensities of the eastward and the westward electrojets, and were found to have evident χ dependences under the normalized condition of the solar wind velocity, V, and of the GSM southward component, Bs, of the interplanetary magnetic field (IMF). The main characteristics of the influence of χ are as follows. (1) AL shows very different χ dependences for different signs of the By component of the IMF. The χ dependences of AL are not independent of its dependence on Bs and V, and hence they have a close relationship with the substorm process initiated from the reconnection of the IMF and geomagnetic field lines at the dayside magnetopause. (2) AU shows very similar χ dependences regardless of the sign of By. The enhancement of AU in the positive range of χ can be interpreted as indicating the important role of solar radiation in determining the magnitude of eastward electrojets.
    View full abstract
    Download PDF (1335K)
  • Some Features of Night Time Electron Density and Temperature in the 2, 500km Region of the Exosphere
    Girija RAJARAM, Tatsuzo OBAYASHI
    1977 Volume 29 Issue 5 Pages 455-469
    Published: 1977
    Released on J-STAGE: March 12, 2010
    DOIhttps://doi.org/10.5636/jgg.29.455
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    The Alouette 2 electrostatic probe measurements of electron density and electron temperature during 1966-1967 show several interesting features in the nighttime 2, 000-3, 000km altitude region. There are seasonal differences in the latitudinal variation of the electron parameters, with Ne forming nocturnal peaks at ±40°geomagnetic latitude during solstices; the summer peak value exceeds the winter peak by almost 50%. The relationship between Ne and Te for these altitudes appears to be rather dependent on latitude, and also exhibits seasonal differences. The Te peak at mid-latitudes forms at a location about 5°lower in geomagnetic latitude than the Ne plasmatrough minimum, and coincides with the lower latitude cliff of the trough.
    The ionic mass in the 2, 500km region is estimated from the observed values of Ne and Te; the values obtained identify with the light ions H+ and He+ between 0 and 40°geomagnetic latitude and a heavy ion species at higher latitudes. The effect of magnetic activity is to decrease Ne and to increase Te at latitudes within ±50°. The plasmatrough in Ne and the corresponding Te peak show a clear equatorward movement during geomagnetic disturbance.
    View full abstract
    Download PDF (1346K)
  • Power Spectrum Analysis of Solar and Geophysical Parameters
    R. P. KANE
    1977 Volume 29 Issue 5 Pages 471-495
    Published: 1977
    Released on J-STAGE: March 12, 2010
    DOIhttps://doi.org/10.5636/jgg.29.471
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Possibility of obtaining power spectra of high resolution by superposition of results of either simple harmonic analysis or Blackman and Tukey spectra of different lags is studied. In the high frequency region (6th and higher harmonics of the fundamental which corresponds to the length of the sample), the superposition methods give results comparable to (and in some aspect better than), those from the Burg method of Maximum Entropy. Results for several artificial samples and a few solar and geophysical parameters obtained by the superposition methods and Burg method are compared. The superposition method is useful only in the high frequency region but does not give spurious peaks and hence seems to be a valuable complement to the Burg method in the high frequency region. For lower frequencies, Burg spectra give better results at larger Lengths of the Prediction Error Filter (LPEF), sometimes far exceeding the usually recommended half data length limit.
    View full abstract
    Download PDF (2239K)
  • Small Scale Fluctuations in the F-Region Critical Frequency at Kodaikanal
    J. Hanumath SASTRI, B. Suryanarayana MURTHY
    1977 Volume 29 Issue 5 Pages 497-502
    Published: 1977
    Released on J-STAGE: March 12, 2010
    DOIhttps://doi.org/10.5636/jgg.29.497
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Some preliminary results obtained on the small scale fluctuations in the F-region critical frequency at Kodaikanal (Dip 3.5°) using 1-min interval ionograms, are presented. Spectral analysis showed the fluctuations to contain dominant periods in the range 5-60min.
    View full abstract
    Download PDF (533K)
  • Planetary Magnetism
    J. A. JACOBS
    1977 Volume 29 Issue 5 Pages 503-505
    Published: 1977
    Released on J-STAGE: March 12, 2010
    DOIhttps://doi.org/10.5636/jgg.29.503
    JOURNAL FREE ACCESS
    Download PDF (230K)
    • |<
    • <
    • 1
    • >
    • >|
feedback
 Top