Journal of geomagnetism and geoelectricity

Characteristics of Solar Energetic Particles which Excite Polar-Cap Blackouts

Kenji SINNO

1961 Volume 13 Issue 1-2 Pages 1-10
Published: 1961
Released on J-STAGE: September 14, 2010

DOIhttps://doi.org/10.5636/jgg.13.1

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Ejection and prapagation of the particles which excite abnormal ionization in the polar upper atmosphere are investigated from some statistical considerations on ionospheric data f-min and cosmic radio observation by riometer.
Relations between the flares and the polar-cap blackouts insist the trapping of particles into the cloud which would be responsible for the geomagnetic disturbances; that is, a part of the energetic particles ejecting from the flare propagate with relativistic velocity in interplanetary space along the twisted solar magnetic line of force extending to the earth and excite the S-type polarcap blackouts having sudden onset within a few hours after flare; on the other hand, another part of the energetic particles ejecting from the flare is trapped into the cloud and is carried with rather low velocity, then the particles would reach the earth by leaking from the cloud and excite the G-type polar-cap blackouts having gradual onset about 10 hours before commencement of geomagnetic storms.

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The Solar Geophysical Events of November 1960

Tatsuzo OBAYASHI

1961 Volume 13 Issue 1-2 Pages 11-25
Published: 1961
Released on J-STAGE: September 14, 2010

DOIhttps://doi.org/10.5636/jgg.13.11

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A series of outstanding solar-geophysical events of November 1960 is described. Results obtained various measurments; solar phenomena, cosmic, rays, ionosphere, geomagnetism and aurorae are summarized and include a theoretical model of disturbances which appears to be consistent to date. It is shown that the events of November 1960 are unique in that they provide not only the information of solar particles up to cosmic ray energy ranges, but also the knowledge of existing interplanetary magnetic flelds. Some important discoveries made in the events are also described briefly.

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Geomagnetic Storm Effects on Charged Particles

Tatsuzo OBAYASHI

1961 Volume 13 Issue 1-2 Pages 26-32
Published: 1961
Released on J-STAGE: September 14, 2010

DOIhttps://doi.org/10.5636/jgg.13.26

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The entry of high energy charged particles is studied taking into account the effect of field distortion due to a geomagnetic storm. By using a modified version of Störmer's theory, the cut-off rigidities of incoming particles are computed for two models of the outer geomagnetic field. The result is compared with the observed effect on precipitation of solar and galactic cosmic rays during the initial and main phases of a geomagntic storm.

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Solar Magnetic Cloud Producing Cosmic-Ray Storm, Magnetic Storm and Type IV Solar Radio Outburst

Yoshiko KAMIYA

1961 Volume 13 Issue 1-2 Pages 33-41
Published: 1961
Released on J-STAGE: September 14, 2010

DOIhttps://doi.org/10.5636/jgg.13.33

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Since the discovery of the cosmic-ray storm by Forbush in 1937, the various attempts have been made to explore its nature. Yet its very cause seems to be unclear in view of the lack of phenomena which are intimately correlated with the cosmic-ray storm. In this study the cause of the cosmic-ray storm has been sought after from observed evidences.
In order to find the cause of cosmic-ray storms, the correlation of the spectral type of solar radio outbursts and cosmic-ray variations and magnetic activities has been studied for the data during the period from July 1957 to December 1960. The results obtained are as follows:
(1) Cosmic-ray storms are closely associated with the radio outbursts of Type IV (continuum). The result indicates that the eruption followed by the radio outburst of Type IV is the cause of cosmic-ray storm.
(2) The size of cosmic-ray and magnetic storm was compared with the heriographic longitude of the eruptions. Large magnetic storms occur after eruptions near the central meridian, while the size of cosmic-ray storm is independent of the heliographic longitude of the eruption.
(3) From these results, a possible model of magnetized corpuscular cloud is presented which seems to be ejected from the sun with eruption followed by Type IV outburst. This model of magnetic cloud is a large total bulk with a core and appears to be able to consistently explain not only the facts above described but also the other earth storms.

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Geomagnetic Secular Variation and Poloidal Magnetic Fields Produced by Convectional Motions in the Earth's Core

Takesi NAGATA, Tsuneji RIKITAKE

1961 Volume 13 Issue 1-2 Pages 42-53
Published: 1961
Released on J-STAGE: September 14, 2010

DOIhttps://doi.org/10.5636/jgg.13.42

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A theory of electromagnetic induction by a convectional fluid motion within the earth's core is attempted in the hope of accounting for the localized intense secular variation in the geomagnetic field as has been found in the Antarctic area. If a toroidal magnetic field of 300 gauss at maximum is supposed to exist in the core, a steady convectional motion described by a spherical harmonic of order 5 and degree 5 can give rise to a poloidal magnetic field (degree 6, order 5) of which the Gaussian coefficient of the magnetic potential amounts to 0.045Γ at the earth's surface provided the radial velocity of the motion is taken as 0.01cm/sec.
A study of the growth of the field tells us that a secular change of the order of 100γ/yr is expected as long as a velocity of 0.1cm/sec is assumed. This order of velocity would not be impossible for such a localized motion as considered here.

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Sound Channel in the Ionosphere

Yoshihito TAKESADA

1961 Volume 13 Issue 1-2 Pages 54-60
Published: 1961
Released on J-STAGE: September 14, 2010

DOIhttps://doi.org/10.5636/jgg.13.54

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The distribution of the sound velocity is obtained by the distribution of the absolute temperature and wind. When the direction of the sound is toward west at the middle latitude, the minimum velocities in summer and winter are estimated to be 210m/s at 70km in height and 280m/s at an altitude of about 90km respectively. The typical paths of sound waves will be shown by Snell's law in the channel with the axis at these altitudes. The maximum of the sound intensity at an altitude of about 90km is reduced to about 0.055dyne/cm². The variation quantity of the density which is originated from sound is less than the value of density under the state of equilibrium. When the value of the density-variation reaches about 10^-8gm/cm³ the wave form of the sound will be transformed into the wind at the altitude of about 90km. During the winter, at the middle latitude, a period of sound waves through the ionosphere comes to about 1sec, corresponding to wave-length of about 280m.

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Effect of Solar Cosmic Rays on the Meteorite Radioactivity

Satio Hayakawa

1961 Volume 13 Issue 1-2 Pages 61-62
Published: 1961
Released on J-STAGE: September 14, 2010

DOIhttps://doi.org/10.5636/jgg.13.61

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