巻号一覧
39 巻, 5 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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Takashi SHIBATA1987 年 39 巻 5 号 p. 247-260
発行日: 1987年
公開日: 2010/09/14
ジャーナル フリーThis paper briefly describes the application of the cross-spectrum analysis technique by multichannel maximum entropy method (MULMEN) to the study of medium-scale traveling ionospheric disturbances (MS-TID) detected with an array of HF Doppler receivers in central Japan during MAP period.
Experiments with artificial data have shown that the MULMEM technique provides by far better spectral estimates than the traditional technique of Blackman-Tukey using FFT algorithm. Several fundamental wave parameters of the TID were then calculated as a function of time by the MULMEM technique. We find that the dynamical (spectral peak traced) multiplet structure of the wave parameters can be well resolved. It is exemplified that such resolution is utilized not only to estimate the number of simultaneous excitation sources but also to detect on occasion the temporal variation in the velocity dispersion of the MS-TID.抄録全体を表示PDF形式でダウンロード (1154K) -
St. P. PAPAMARINOPOULOS1987 年 39 巻 5 号 p. 261-270
発行日: 1987年
公開日: 2010/09/14
ジャーナル フリーThe geomagnetic intensity variations in northern Greece have been recorded in Byzantine vases. Minute cylindrical samples have been extracted from vases and measured with a cryogenic magnetometer using a modified version of the Thellier method. The geomagnetic intensity ratio FA/FD, which expresses the ancient field intensity upon the present day field intensity, exhibits values 1.20 between 3-400, 1.49 between 4-700, 1.51 at 1100, 0.89 at 1400, 1.07 at 1500 and 0.94 at 1650yr. A. D.抄録全体を表示PDF形式でダウンロード (874K) -
Leroy R. ALLDREDGE1987 年 39 巻 5 号 p. 271-296
発行日: 1987年
公開日: 2010/09/14
ジャーナル フリーOne hundred-sixty circular current loops with radial axes were fitted by least squares to the 899 spherical harmonic coefficients of a 29th degree model. In the first case, the parameters that were fitted for each loop were the normalized magnetic moment, the distance from the center of the Earth to the current element, the colatitude and E. longitude of the loop axis, and one-half of the central apex angle of the loop. For this case, two of the loops converged near the inner-core outer-core boundary. They accounted for most of the dipolar field. Twenty of the loops, all with much smaller magnetic moments than the two deep loops, converged in the distance range of 0.42 to 0.67 Earth's radius from the center of the Earth. The other 138 loops, after many iterations, were located at distances between 0.81 and 1.0 Earth's radius from the center of the Earth. The loops with radial distances between 0.21 and 0.67 Earth's radius from the center of the Earth are referred to as “core” loops and those at distances greater than 0.81 Earth's radius as “crustal” loops. The spherical harmonic coefficients from these 160 loops, when subtraced from the 899 coefficients of the original model, left a root-mean-square residual of only 0.2nT. A second case was tried which constrained the 138 “crustal” loops to be at 0.996 Earth's radius (25.5km depth). In this case, the root-mean-square residual of the spherical harmonic coefficients from the original model was 0.9nT.抄録全体を表示PDF形式でダウンロード (2253K) -
Takehiko ASO, Sakae ITO, Susumu KATO1987 年 39 巻 5 号 p. 297-305
発行日: 1987年
公開日: 2010/09/14
ジャーナル フリーNumerical calculation of the atmospheric diurnal tide in the middle atmosphere has been carried out for the equinoctial condition with emphasis on the effect of latitudinal temperature gradient and background mean zonal wind. It is shown that in the mid-to-low latitude region, propagating (1, 1) mode is affected, especially in its phase, by the equinoctial westerly wind and phase lag at 90km is 4-5 hours relative to the no wind condition. The result might account for part of the tidal variability observed in the mesosphere and lower thermosphere.抄録全体を表示PDF形式でダウンロード (807K) -
Toshitsugu YAMAZAKI1987 年 39 巻 5 号 p. 307-312
発行日: 1987年
公開日: 2010/09/14
ジャーナル フリーPDF形式でダウンロード (538K)
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