2-day, 3-day, and 5-6-day oscillations of the geomagnetic field detected by principal component analysis
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- Yamada Yuji
- Kakioka Magnetic Observatory
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説明
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 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.
収録刊行物
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- Earth, Planets and Space
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Earth, Planets and Space 54 (4), 379-392, 2002
地球電磁気・地球惑星圏学会 、公益社団法人 日本地震学会、特定非営利活動法人 日本火山学会、日本測地学会、日本惑星科学会
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詳細情報 詳細情報について
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- CRID
- 1390001206512488448
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- NII論文ID
- 10008635045
- 130003780889
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- NII書誌ID
- AA11211921
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- ISSN
- 18805981
- 13438832
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- NDL書誌ID
- 6142299
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- 本文言語コード
- en
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- データソース種別
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- JaLC
- NDL
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