Mid-Holocene regional reorganization of climate variability: Analyses of proxy data in the frequency domain
Mid-Holocene regional reorganization of climate variability: Analyses of proxy data in the frequency domain
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DOI：
10.1016/j.palaeo.2010.09.019
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发表时间：
2010-12
期刊：
影响因子：
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通讯作者：
K. Wirtz;G. Lohmann;K. Bernhardt;C. Lemmen
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文献类型：
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作者：
K. Wirtz;G. Lohmann;K. Bernhardt;C. Lemmen
全新世气候的反复变化定义了自然变化的范围，应该将人类干扰地球系统的特征与之进行比较。由于过去9000-11000年来越来越多的古气候记录，在全球范围内描述全新世气候变异性变得越来越容易。在这里，我们整合了124个不同类型的代理时间序列(例如，δ18O，岩屑成分)，并应用改进的Lomb-Scargle谱分析。在移动时间窗中自举数据之后，我们观察到在全新世中期产生或消失周期模的概率增加。光谱变化的空间自相关有力地揭示了这种(In)模的激活是在次大陆大小的区域星系团中组织的。在这些星系团中，光谱特性的变化出人意料地一致，尽管潜在的气候变量不同。气候系统的振荡被放大，特别是在上升流区，而在北大西洋则受到抑制。我们通过对时间序列中的事件进行计数来交叉检查频谱分析，并针对个别记录中可能的测年错误或针对单个事件的高估进行了测试。不同机制的组合可能影响了气候子系统之间的耦合强度，使这些子系统或多或少容易发生振荡。
Recurrent shifts in Holocene climate define the range of natural variability to which the signatures of human interference with the Earth system should be compared. Characterization of Holocene climate variability at the global scale becomes increasingly accessible due to a growing amount of paleoclimate records for the last 9000–11000yr. Here, we integrate 124 proxy time-series of different types (e.g., δ18O, lithic composition) and apply a modified Lomb–Scargle spectral analysis. After bootstrapping the data in moving time windows we observe an increased probability for generation or loss of periodic modes at the mid-Holocene. Spatial autocorrelation of spectral changes robustly reveals that this (in)activation of modes was organized in regional clusters of sub-continental size. Within these clusters, changes in spectral properties are unexpectedly homogeneous, despite different underlying climatological variables. Oscillations in the climate system were amplified especially at the upwelling areas and dampened in the North Atlantic. We cross-checked the spectral analysis by counting events in the time-series and tested against possible dating errors in individual records or against an overestimation of singular events. A combination of different mechanisms may have affected the coupling intensity between climate subsystems, turning these more or less prone to oscillations.