巻号一覧
20 巻, 1 号
選択された号の論文の7件中1～7を表示しています
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M. J. S. JOHNSTON, F. D. STACEY1968 年 20 巻 1 号 p. 1-6
発行日: 1968/03/20
公開日: 2010/09/14
ジャーナル フリーMeasurements of the magnetic moments of motor vehicles indicate moments in the range 6×104e.m.u. to 13×104e.m.u. for small to medium sized vehicles. These moments are substantially stronger than for solid bodies of similar masses. To avoid disturbance to a magnetometer of sensitivity 0.5 gamma, vehicles must not be allowed to come closer than 40 metres. This rule should be observed particularly in the selection of sites for magnetometers used to look for local seismomagnetic effects.抄録全体を表示PDF形式でダウンロード (673K) -
Kazuhiro KITAZAWA, Kazuo KOBAYASHI1968 年 20 巻 1 号 p. 7-19
発行日: 1968/03/20
公開日: 2010/09/14
ジャーナル フリーBy measuring the natural remanent magnetization of potteries from Bolivia and Ecuador, the intensity of the ancient geomagnetic field was compared with that of the present. These potteries cover the period of about 2000 B. C. to 1200 A. D. It was concluded that the intensities of 2000 B. C. and 0 A. D. were nearly equal to the present intensity, and that of 700 A. D. was about 1.5 times as large as the present one. In this study Thellier's stepwise heating method was used to estimate the intensities of the ancient geomagnetic field. Some samples exhibited anomalous shapes of thermal demagnetization curves of natural remanent magnetization. An experimental examination to clarify the origin of these anomalies indicated that some samples might have been reheated at a temperature somewhat below the highest Curie temperature sometime after the production of the potteries. A criterion to select useful samples was postulated on the basis of these experimental results and only the proper samples were used for the present purpose.抄録全体を表示PDF形式でダウンロード (2126K) -
V. V. SOMAYAJULU, B. A. P. TANTRY1968 年 20 巻 1 号 p. 21-31
発行日: 1968/03/20
公開日: 2010/09/14
ジャーナル フリーSonagrams of a large number of whistlers recorded during the magnetic storm of 13th to 15th January, 1967, have been presented to illustrate the formation of ducts corresponding to path latitudes of 24°, 27°, and 31°and the VLF ducts formation during the main phase of the magnetic storm has been attributed to the enhanced electron density produced in the F2-region heights and above upto about 2 earth's radii. A correlation between the Kp-index and the whistler occurrence during the storm has been drawn and the enhanced whistler activity has been explained in terms of additional VLF ducts produced for whistler mode of propagation.
From a large number of whistlers recorded during the storm, it is inferred, contrary to the idea of Smith, that though the formation of ducts can take place in much less than 30 minutes, once the duct has formed it can persist for at least 2 to 3 days.
It is found that usually whistlers have pure gliding tones during quiet days while most of the whistlers recorded during the disturbed days show a large amount of diffuseness, which has been attributed to the propagation of VLF waves within a wide area of the duct. This is in contrast to the idea of Crouchley and Finn who show that diffuseness increases with dispersion.
From the diffuseness of sonagrams of the whistlers, the effective width of the VLF ducts for the waves of 5Kc/s have been calculated and are found to vary from 15km to 25km for normal whistlers and 40 to 180km for those recorded during the magnetically disturbed days.抄録全体を表示PDF形式でダウンロード (4103K) -
T. KITAMURA, J. A. JACOBS1968 年 20 巻 1 号 p. 33-44
発行日: 1968/03/20
公開日: 2010/09/14
ジャーナル フリーA new method is presented of determining the magnetospheric plasma density distribution, using long period geomagnetic micropulsations (period 45-600sec.). Long period micropulsations are assumed to be caused by resonant oscillations of geomagnetic lines of force in the magnetosphere. Eliminating the time dependent factor from the wave equations leads to an ordinary differential equation that depends on a spatial parameter only. With certain boundary conditions assigned beforehand (which may be determined by observation), the differential equation uniquely determines the ‘spatial form’ of the oscillation if the plasma density distribution is known. A distribution is determined so that the spatial form is that of the fundamental and of the second harmonic, since these modes are the most likely to be excited. Results are compared with other investigations-good agreement is obtained with those from the IMP II satellite.抄録全体を表示PDF形式でダウンロード (1370K) -
Mitsuo KEIMATSU, Naoshi FUKUSHIMA, Takesi NAGATA1968 年 20 巻 1 号 p. 45-50
発行日: 1968/03/20
公開日: 2010/09/14
ジャーナル フリーIn order to trace the secular variation of the geomagnetic field in historic time, the documents of ancient aurorae can be utilized. In China, Korea and Japan, there are a number of valuable records, which can be reasonably supposed to describe the events of auroral appearance. After a comparison of these descriptions with those in Europe, the archaeo-secular variation in the geomagnetic field can be inferred. A preliminary examination of the auroral appearance on the same day in the Occident and Orient suggests that the geomagnetic dipole axis might have been inclined towards China around 11-12th centuries AD.抄録全体を表示PDF形式でダウンロード (715K) -
A. SUZUKI, H. MAEDA1968 年 20 巻 1 号 p. 51-53
発行日: 1968/03/20
公開日: 2010/09/14
ジャーナル フリーPDF形式でダウンロード (265K) -
Yoshihito TAKESADA1968 年 20 巻 1 号 p. 55-56
発行日: 1968/03/20
公開日: 2010/09/14
ジャーナル フリーPDF形式でダウンロード (148K)
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