Journal of geomagnetism and geoelectricity

Motion of Low-Energy Solar Cosmic Ray Particles in the Earth's Magnetic Field

Kunitomo SAKURAI

1961 Volume 12 Issue 2 Pages 59-69
Published: 1961
Released on J-STAGE: September 14, 2010

DOIhttps://doi.org/10.5636/jgg.12.59

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We calculate the orbits of the low-energy solar cosmic ray particles in the earth's dipole magnetic field and then estimate on their asymptotic velocity vectors before entering this magnetic field. Although the incident region of these particles is restricted in the area of higher geomagnetic latitudes than 60°, it is clear that there are anisotropic effects, i. e. impact zone effects for the incidence of these particles. Furthermore, the precipitation lines of the incidence will be shown to be circular around the geomagnetic north pole.
Next, it will be shown from the comparison of the calculated results with the observed data that, in the initial stage of the incidence, these low-energy cosmic ray particles tend to impinge upon the earth anisotropically, in accordance with the expectation from the calculated results, and that, slightly before the onset of geomagnetic Sc storms, their anisotropic incidence changes into isotropic one, although there are some exceptional cases. Finally, criticisms and a possible explanation on the features of their incidence after the onset of geomagnetic Sc storms will be proposed.

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On the Relativistic Electrons in the Solar Atmosphere

Kunitomo SAKURAI

1961 Volume 12 Issue 2 Pages 70-76
Published: 1961
Released on J-STAGE: September 14, 2010

DOIhttps://doi.org/10.5636/jgg.12.70

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We consider the various processes, in solar atmosphere, of the relativistic electrons ejected in association with flares and examine how these electrons will lose their energies.
In view of the above examination, we can show that these electrons will be trapped in the sunspot magnetic fields (∼100 gauss) and then lose the majority of their energies through the synchrotron radiation. So, the radio waves emitted by these synchrotron radiation processes will be observed as the type IV outbursts.

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On the Origin of V. L. F. Noise in the Earth's Exosphere

Tadanori ONDOH

1961 Volume 12 Issue 2 Pages 77-83
Published: 1961
Released on J-STAGE: September 14, 2010

DOIhttps://doi.org/10.5636/jgg.12.77

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At present, there are some theories being able to explain the frequency characteristic of dawn chorus. In these theories, the natural thermal noise excited in a manner similar to the operation of a travelling-wave tube, the Doppler shifted proton cyclotron radiation and the Cerenkov radiation are considered as the origin of V. L. F. noise in the earth's exosphere respectively. This paper indicates that the Cerenkov radiation will be the most effective with respect to the emission energy in the above mentioned mechanisms in the earth's exosphere and that Cerenkov radio emissions generated by high speed protons (1.4×10⁴km/sec) precipitating into the ionized exosphere along the earth's magnetic field may be excited simultaneously by the operation of the mechanism similar to a travelling-wave tube due to charged particles different from those causing the Cerenkov radiation relatively near the earth less than about 4 earth radii from the center of the earth and then propagate toward the earth in the whistler mode.

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Geomagnetic Secular Variation during the Period from 1955 to 1960

Takesi NAGATA, Yasuhiko SYONO

1961 Volume 12 Issue 2 Pages 84-98
Published: 1961
Released on J-STAGE: September 14, 2010

DOIhttps://doi.org/10.5636/jgg.12.84

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The isoporic charts of X, Y and Z of geomagnetic secular variation during the period from 1955 to 1960 are constructed based on data observed at 99 stations over the earth's surface including the Antarctic region, and illustrated in Figs. 1-9. Equivalent current system of the variation on the earth's core's surface is shown in Figs. 11-13.
From the results of the spherical harmonic analyses of these isoporic charts, it is concluded that (a) the earth's magnetic dipole is decreasing in moment with the rate of -4.4×10²²emu/yr, magnitude of the moment at 1960.0 being 8.046×10²⁵emu; (b) the eccentric dipole is drifting westwards by 18′/yr, northwards by 12′/yr, and outwards by 3.4×10^-4× the earth's radius/yr. It is shown that the other harmonics, are drifting mostly westwards also with the rate of several decimals of a degree per year.
On the other hand, very intense foci of isopors are found in the Antarctic region, amounting to about 200γ/yr in Z. The current change on the earth's core's surface equivalent to the foci amount to about 0.1Amp/cm/yr. This value is strikingly large compared with intensity of the equivalent current of the earth's magnetic dipole, which is about 0.5Ampere/cm in this region.

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Abstracts of the Papers Presented at the 28th Annual Meeting, Kyoto, Oct. 30-Nov. 1, 1960

1961 Volume 12 Issue 2 Pages 99-116
Published: 1961
Released on J-STAGE: September 14, 2010

DOIhttps://doi.org/10.5636/jgg.12.99

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