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首页> 外文期刊>Earth, planets and space: EPS >2-day, d-day, and 5-6-day oscillations of the geomagnetic field detected by principal component analysis
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2-day, d-day, and 5-6-day oscillations of the geomagnetic field detected by principal component analysis

机译：通过主成分分析检测到地磁场的2天，d天和5-6天振荡

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摘要

The day-to-day variation of the geomagnetic daily variation has been examined using hourly data of the Z component at Chichijima (geographic 27.15°N, 142.30°E; geomagnetic 18.11°N) in the northwestern Pacific Ocean. Principal component analysis is applied to the data from 1970 to 1992, and 2-day, 3-day, and 5-6-day oscillations were extracted from the day-to-day variation of the daily profile. The temporal variations of both the waveform and amplitude of each oscillation were clarified. The fluctuation associated with any of these oscillations is confined to the sunlit hours, which infers the oscillations are originated from ionospheric currents. Although the amplitudes of the oscillations are variable, they seem to be present almost continuously. Each oscillation is expressed primarily by the periodic increase and decrease of the amplitude of the quiet time daily variation, and the deviation from the normal level statistically amounts to 12% (3-day oscillation), 15% (5-6-day oscillation), and 17% (2-day oscillation) of the mean amplitude of the daily variation. There are cases, however, for which the magnitude is considerably amplitudes of the oscillations are variable, they seem to be present almost continuously. Each oscillation is expressed primarily by the periodic increase and decrease of the amplitude of the quiet time daily variation, and the deviation from the normal level statistically amounts to 12% (3-day oscillation), 15% (5-6-day oscillation), and 17% (2-day oscillation) of the mean amplitude of the daily variation. There are cases, however, for which the magnitude is considerably amplified during a short duration. There also exist the oscillations that show the three periods in the pattern of the daily variation as well as in intensity. The result of analysis of day-to-day variations at other four stations indicates that the oscillations are phenomena having some latitudinal extent across the geomagnetic equator.
机译：地磁每日变化的每日变化已使用西北太平洋奇奇玛岛（地理27.15°N，142.30°E;地磁18.11°N）的Z分量的每小时数据进行了检验。将主成分分析应用于1970年至1992年的数据，并从每日剖面的每日变化中提取了2天，3天和5-6天的振荡。阐明了每个振荡的波形和幅度的时间变化。与这些振荡中的任何一个相关的波动都限于日照时间，这表明该振荡源自电离层电流。尽管振荡的幅度是可变的，但它们似乎几乎连续存在。每次振荡主要通过静默时间每日变化幅度的周期性增加和减少来表示，与正常水平的偏差统计上分别为12％（3天振荡），15％（5-6天振荡） ，以及每日变化的平均幅度的17％（2天振荡）。但是，在某些情况下，振幅的大小相当大，振荡的振幅是可变的，它们似乎几乎连续存在。每次振荡主要通过静默时间每日变化幅度的周期性增加和减少来表示，与正常水平的偏差统计上分别为12％（3天振荡），15％（5-6天振荡） ，以及每日变化的平均幅度的17％（2天振荡）。但是，在某些情况下，幅度在短时间内会大大放大。还存在以日变化形式和强度形式显示三个周期的振荡。对其他四个台站日常变化的分析结果表明，这种振荡是在地磁赤道上具有一定纬度范围的现象。

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