巻号一覧
15 巻, 2 号
選択された号の論文の5件中1～5を表示しています
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E. H. Vestine, W. L. Sibley, J. W. Kern, J. L. Carlstedt1963 年 15 巻 2 号 p. 47-72
発行日: 1963年
公開日: 2010/09/14
ジャーナル フリーThe geomagnetic field is analyzed by spherical harmonics. Series representations in spherical harmonics of geomagnetic field charts are compared for truncation of the series at terms of degree 6, 8, 10, and 12. Scalings are at a uniformly spaced latitude-longitude grid from both U.S. and U.S.S.R. isomagnetic charts for 1955.0. Some minor but undesirable effects are mentioned that arise because of the uniform angular spacing of data points scaled from charts. The variation of the earth's magnetic moment and the location of the dipole axis since 1835 is described and discussed. It is shown that spherical harmonic coefficients of secular change for 1912.5, 1922.5, 1932.5, and 1942.5 seem roughly compatible with those of Nagata and Oguti for 1958.5, even though earlier data analyzed were defective in Antarctica; evidently the precision of determination of the coefficients of secular change is not high. Finally, an extrapolation of the geomagnetic field into the earth's interior is described.抄録全体を表示PDF形式でダウンロード (1844K) -
E. H. VESTINE, W. L. SIBLEY, J. W. KERN, J. L. CARLSTEDT1963 年 15 巻 2 号 p. 73-89
発行日: 1963年
公開日: 2010/09/14
ジャーナル フリーA numerical integration method for analyzing the geomagnetic field is developed from Poisson's integral. A new surface grid, suitable for use with integral analysis, is described. This grid is based on subdivisions of a spherical icosahedron, and its points are almost uniformly spaced over a sphere. This integration method is applied to calculations of field values, field lines, and conjugate points. The results are compared with those of earlier spherical-harmonic analyses by Vestine and Sibley. A comparison is also made between those conjugate points calculated by spherical harmonics from different sets of coefficients derived from various sets of isomagnetic charts.抄録全体を表示PDF形式でダウンロード (1715K) -
Tadanori ONDOH1963 年 15 巻 2 号 p. 90-108
発行日: 1963年
公開日: 2010/09/14
ジャーナル フリーIonospheric absorptions of VLF emissions at the auroral zone have been calculated along a geomagnetic line of force connecting with the earth's surface at geomagnetic latitude of 64° by using the longitudinal approximation of the Appleton-Hartree formula and data of rocket sounding at Ft. Churchill and of auroral luminosity profile at College, Alaska.
Ionospheric absorptions at 4kc/s between 50km and 170km height are of 33.1dB, 15.4dB, 16.9dB, and 2.2dB for a daytime ionosphere during total polar black-out, a quiet ionosphere near noon, a midnight ionosphere during diffuse aurora, and a quiet ionosphere at winter midnight respectively. Therefore the lack of VLF emissions during total polar black-out at high latitudes may be due to the marked increase of the absorption in the ionosphere, especially in D layer.
On the other hand, it seems likely that particles producing auroras and geomagnetic disturbances around E layer do not cause considerable absorption of the VLF emissions, and that the power of VLF emissions is originally weak in the exosphere on night side at the auroral zone. The absorption of 15.4dB in the quiet ionosphere near noon suggests that the original power of VLF emissions in the exosphere is of the order of 3.5×10-13-3.5×10-15W.m.-2(c/s)-1 in the daytime. The diurnal variation in maximum chorus frequency at high latitudes may be explained by relative increase of ionospheric absorption during the daytime for frequencies above a few kilo-cycles.抄録全体を表示PDF形式でダウンロード (1377K) -
S. A. A. KAZMI1963 年 15 巻 2 号 p. 109-115
発行日: 1963年
公開日: 2010/09/14
ジャーナル フリーThe study of diurnal variation in the frequencies and amplitudes of magnetic sudden commencements (SCS) and sudden impulses (SIS) recorded at Quetta (lat. 30°11′N; long. 66°57′E), during the period 1953-1962 indicates that SCS and SIS are more frequent near the sunrise and sunset hours with maxima around 06h and 18h local time (L.T.). This does not conform to the curves obtained by Newton (1948) and Ferraro & others (1951) which exhibit a maximum at 13h L. T. and two minima at 08h and 20h L. T. respectively.
The mean hourly values of the amplitude ‘y’ of SCS & SIS do not seem to exhibit any marked local time effect. The daytime enhancement in ‘y’ and the similarity between the diurnal variation of amplitude of SCS & SIS and Sq-variation found at Huancayo, Kodaikanal and Alibag is also absent, on the other hand a sharp minimum in the amplitude curve around 07h L. T. gives weight to Ferraro's (1954) contension that during the day-lit hemisphere the higher conductivity of the ionosphere tends to shield the station below from the external magnetic field produced by corpuscular stream.
No seasonal variation in the monthly frequency of SCS & SIS is discernable but the mean monthly amplitude curve exhibits marked enhancement in the size of SCS & SIS during summer months.
The curves for the annual mean number and yearly mean amplitudes of SCS & SIS and yearly mean Sq-range show striking similarity to the curve for the annual mean sunspot numbers. A linear relationship of the type y=11.6+0.097s between the amplitude ‘y’ and the relative sunspot numbers ‘s’ has been worked out for Quetta.抄録全体を表示PDF形式でダウンロード (584K) -
T. Nagata, M. Sawada1963 年 15 巻 2 号 p. Suppl1-Suppl42
発行日: 1963/11/30
公開日: 2011/08/11
ジャーナル フリーPDF形式でダウンロード (2570K)
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