Journal of geomagnetism and geoelectricity
Online ISSN : 2185-5765
Print ISSN : 0022-1392
ISSN-L : 0022-1392
Volume 17, Issue 1
Displaying 1-6 of 6 articles from this issue
  • Ken-ichi MAEDA
    1965 Volume 17 Issue 1 Pages 1-21
    Published: July 20, 1965
    Released on J-STAGE: September 14, 2010
    JOURNAL FREE ACCESS
    The electrostatic field communicated from the dynamo region (the E region) into the magnetosphere will affect the motion of the trapped electrons. The case of electrons with energy ranging from 300eV to 30keV is treated. The electron orbit between two conjugate mirror points shifts earthward (inward) during night and outward during daytime. At the same time the mirror points shifts downwards and equatorwards (or upwards and polewards) during night (or daytime). The integrated effect on the apex height of an orbit and its diurnal variation are given.
    The number of inelastic collisions of an electron is calculated and the effective lifetime of a trapped electron is estimated. By the use of this result a possibility is studied whether the trapped electrons, coming down to the mirror point as low as 300-500km, can be the principal cause of ionization of the F region during night.
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  • Takao SAITO
    1965 Volume 17 Issue 1 Pages 23-44
    Published: July 20, 1965
    Released on J-STAGE: September 14, 2010
    JOURNAL FREE ACCESS
    The result of Part I of this series is amplified by using the data from 1959 to 1964.
    It is pointed out that the superposed epoch method which has been used for the solar M-region study may draw many diverse conclusions. Contraversity among four hypotheses, Allen's, Mustel's, Dessler-Fejer's and Piddington's, on the mechanism of 27-day recurrent geomagnetic disturbance is partly due to obscurity in the superposed epoch method. In order to obtain exact locations of M-regions in relation to solar active regions, a geomagnetic pulsation pc 3 and calcium plage are applied as the representatives among various solar and terrestrial phenomena. An M-region temporally obtained by putting ∑Kc 3, the daily sum of pc 3 index, back by three days is called an apparent M- (or AM-) region. All diverse relations between AM-region and active region obtained by the superimposed method cannot be uniquely interpreted by any of the above four hypotheses. It is shown that such the different relations cannot be interpreted by a radial solar wind emission from the sun, which is the fundamental assumption especially in both Allen's and Mustel's hypotheses. Thus, the deflection hypothesis based on the following assumptions is introduced. (1) The solar winds with high velocity responsible for M-disturbances are emitted generally in the non-radial direction with respect to the solar surface. (2) Most of the wind particles are supplied from a region of Ca plage or of its remnant (abbreviated to PR-region). This hypothesis is applied for a practical explanation of the different relations between AM- and PR-regions which have appeared during the present solar cycle.
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  • II. Pre-sc Increase of WWV 20 and 25Mc/s Field Intensity and of f0F2 in High Latitudes
    Tadanori ONDOH, Koji OBU
    1965 Volume 17 Issue 1 Pages 45-57
    Published: July 20, 1965
    Released on J-STAGE: September 14, 2010
    JOURNAL FREE ACCESS
    Storm-time variations of WWVV 25, 20, 15, 10, 5, and 2.5Mc/s, and of the average deviations of f0F2 from the monthly median are examined for fifty geomagnetic storms during August 1957-February 1959. Abnormal increases of field intensity of WWV 20 and 25Mc/s, and of Δf0F2 occur from about 18 hours before a geomagnetic storm sudden commencement. Such field intensity increases have not statistically been found below 15Mc/s. The abnormal increases of field intensity at 20 and 25Mc/s may be interpreted as being due to a decrease in deviative absorption associated with an increase in f0F2 for the penetration frequency near 20-25Mc/s. The low latitude boundary of the pre-sc increase of f0F2 lies around 57°. 0N in geomagnetic latitude. A pre-sc increase of Δf0F2 in high latitudes is also found for geomagnetic storms associated with PCA during August 1957-February 1959.
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  • I. Cloud Discharge
    Tosio TAKEUTI
    1965 Volume 17 Issue 1 Pages 59-68
    Published: July 20, 1965
    Released on J-STAGE: September 14, 2010
    JOURNAL FREE ACCESS
    To study the electrical process in cloud discharge and the charge distribution in thunderclouds, the electrostatic field changes due to a cloud discharge have been recorded simultaneously at three field sites. It has been found that there are three types of thundercloud: Type I predominantly produces an upper-positive vertical dipole discharge, Type II an inclined or horizontal discharge, Type III an upper-negative vertical discharge. Type III is found likely to have more or less thin distribution of negative electric charge on top of or just above it. The streamer velocity ranges mostly in 1-2×106cm/sec, and is neary kept constant through out the whole duration of a discharge. The path length of a vertical discharge is usually of 2km or less, while that of a horizontal one is mostly longer than this value. The electric charge quantity neutralized in a cloud discharge often exceeds 100 coulombs, which is in a good agreement with Hatakeyama's report, while it is appreciably larger than the value presented in other reports. A cloud discharge consists of many local discharges being distributed on its path at 200m interval in average. The charge dissipated by a local discharge is estimated to be of about 1 coulomb or more.
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  • Rikio MAEDA, Tsuneji RIKITAKE, Takesi NAGATA
    1965 Volume 17 Issue 1 Pages 69-93
    Published: July 20, 1965
    Released on J-STAGE: September 14, 2010
    JOURNAL FREE ACCESS
    The vertical components of geomagnetic variations at times of sudden commencements of magnetic storms apparently show an irregular distribution over the world, in contrast to the simultaneous horizontal field-change. The geomagnetic vertical field-change depends on the topographic condition at magnetic observatories, and this seems to be explained from the viewpoint of electromagnetic induction within the earth's outermost layer. An earth model with uniform electric conductivities is the zero-order approximation, with which the behavior of sudden commencements of geomagnetic storms at continental stations can be explained. The earth seems to act as a perfect conductor to screen the geomagnetic field-change under the earth surface (I10/E10→1/2) for sudden commencements of extremely short rise-time, so far as the data of continental stations are concerned. In a higher-order approximation for the electrical conductivity-distribution of the earth's outermost layer, the conductivity is non-uniform owing to the sea-land contrast over the world. When the non-uniformity of electric conductivity in the earth's outermost layer is simply taken into account, the observed tendency of the vertical geomagnetic variation at most non-continental stations can also be reasonably explained by the electromagnetic induction, except in special areas such as the Japan Islands and the Antarctic coast.
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  • T. RIKITAKE
    1965 Volume 17 Issue 1 Pages 95-97
    Published: July 20, 1965
    Released on J-STAGE: September 14, 2010
    JOURNAL FREE ACCESS
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