Assessing the importance and expression of the 6 year geomagnetic oscillation
Assessing the importance and expression of the 6 year geomagnetic oscillation
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DOI：
10.1029/2012jb009405
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发表时间：
2012-10
影响因子：
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通讯作者：
L. Silva;L. Jackson;J. Mound
中科院分区：
文献类型：
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作者：
L. Silva;L. Jackson;J. Mound
[1]已知剩余日长观测值的一阶时间导数包含独特的6年周期振荡。在这里，我们的理论，通过在核心的顶部的流动加速度相同的周期性应该出现在地磁长期加速度。我们使用的长期加速度的CHAOS-3和CM 4地磁场模型恢复频谱，通过传统的傅立叶分析和经验模式分解。我们识别了地磁长期加速度中的6年周期信号，并描述了它的空间行为。这个信号似乎与最近的地磁急动密切相关。我们还确定了一个2.5年的周期信号在混沌3未知的起源。该信号是严格轴向偶极的，并且不存在于其他磁性或大地测量时间序列中。
[1] The first time derivative of residual length-of-day observations is known to contain a distinctive 6 year periodic oscillation. Here we theorize that through the flow accelerations at the top of the core the same periodicity should arise in the geomagnetic secular acceleration. We use the secular acceleration of the CHAOS-3 and CM4 geomagnetic field models to recover frequency spectra through both a traditional Fourier analysis and an empirical mode decomposition. We identify the 6 year periodic signal in the geomagnetic secular acceleration and characterize its spatial behavior. This signal seems to be closely related to recent geomagnetic jerks. We also identify a 2.5 year periodic signal in CHAOS-3 with unknown origin. This signal is strictly axially dipolar and is absent from other magnetic or geodetic time series.