Nonlinear Processes in Geophysics Climate spectrum estimation in the presence of timescale errors
Nonlinear Processes in Geophysics Climate spectrum estimation in the presence of timescale errors
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发表时间：
2009
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通讯作者：
M. Mudelsee;D. Scholz;R. Röthlisberger;D. Fleitmann;A. Mangini;E. W. Wolff
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作者：
M. Mudelsee;D. Scholz;R. Röthlisberger;D. Fleitmann;A. Mangini;E. W. Wolff
我们介绍了一种算法（称为REDFITmc 2）的频谱估计中存在的时标误差。它是基于不均匀间隔时间序列的Lomb-Scargle周期图，结合Welch的重叠段平均过程，自举偏差校正和持久性估计。时间尺度误差被参数化建模，并包括在模拟中，用于确定（1）红噪声AR（1）替代方案的频谱的上限和（2）频谱峰值频率的不确定性。应用REDFITmc 2冰芯和石笋记录的古气候允许一个更现实的评价谱峰比忽略这个来源的不确定性。结果支持定性的直觉，更强的影响，频谱估计（降低检测能力和增加频率的不确定性）发生较高的频率。算法REDFITmc 2带来的剩余信息是这些影响被量化。关于时间尺度的构建，不仅固定点、测年误差和年龄-深度模型的函数形式起作用。此外，所有时间点的联合分布（序列相关、地层顺序）确定频谱估计。
We introduce an algorithm (called REDFITmc2) for spectrum estimation in the presence of timescale errors. It is based on the Lomb-Scargle periodogram for unevenly spaced time series, in combination with the Welch’s Overlapped Segment Averaging procedure, bootstrap bias correction and persistence estimation. The timescale errors are modelled parametrically and included in the simulations for determining (1) the upper levels of the spectrum of the rednoise AR(1) alternative and (2) the uncertainty of the frequency of a spectral peak. Application of REDFITmc2 to ice core and stalagmite records of palaeoclimate allowed a more realistic evaluation of spectral peaks than when ignoring this source of uncertainty. The results support qualitatively the intuition that stronger effects on the spectrum estimate (decreased detectability and increased frequency uncertainty) occur for higher frequencies. The surplus information brought by algorithm REDFITmc2 is that those effects are quantified. Regarding timescale construction, not only the fixpoints, dating errors and the functional form of the age-depth model play a role. Also the joint distribution of all time points (serial correlation, stratigraphic order) determines spectrum estimation.