Orbital Signals in Carbon Isotopes: Phase Distortion as a Signature of the Carbon Cycle
Orbital Signals in Carbon Isotopes: Phase Distortion as a Signature of the Carbon Cycle
复制标题
DOI：
10.1002/2017pa003143
复制
发表时间：
2017-11
期刊：
影响因子：
--
通讯作者：
J. Laurin;B. Růžek;M. Giorgioni
中科院分区：
文献类型：
--
作者：
J. Laurin;B. Růžek;M. Giorgioni
本文利用同位素质量平衡模型研究了Milankovitch时间尺度上海洋-大气系统碳同位素组成（δ 13 C）对调幅扰动的响应。我们确定了一个系统的相位失真，这是固有的泄漏的功率从载波进动信号的调制偏心率在全球碳循环。起源部分类似于正弦信号中的简单累积效应，反映了碳在海洋-大气储层中的停留时间。然而，起源和实际影响的细节是不同的。在调幅信号中，变形表现为405 kyr偏心周期滞后于短（~100 kyr）偏心周期的调幅（AM）。重要的是，在碳循环转移过程中，AM的相位保持稳定，从而提供了一个参考框架，以评估405 kyr术语的失真。相关系可以帮助（1）识别δ 13 C的沉积和成岩特征，（2）解释天文信号通过气候系统的路径。该方法说明了Albian和渐新世记录的案例研究，使用一种新的计算工具EPNOSE（在不确定和nisy SEries阶段的评价）。类似的相位失真发生在碳循环的其他组成部分，包括大气中的二氧化碳水平;因此，要充分了解天文时间尺度上的因果关系，古气候模型可能需要结合现实的，调幅的日照，而不是单色正弦近似。最后，滞后δ 13 C响应的检测可以帮助减少调整到405 kyr周期的天体年代学年龄模型的不确定性。
Isotopic mass balance models are employed here to study the response of carbon isotope composition (δ13C) of the ocean-atmosphere system to amplitude-modulated perturbations on Milankovitch time scales. We identify a systematic phase distortion, which is inherent to a leakage of power from the carrier precessional signal to the modulating eccentricity terms in the global carbon cycle. The origin is partly analogous to the simple cumulative effect in sinusoidal signals, reflecting the residence time of carbon in the ocean-atmosphere reservoir. The details of origin and practical implications are, however, different. In amplitude-modulated signals, the deformation is manifested as a lag of the 405 kyr eccentricity cycle behind amplitude modulation (AM) of the short (~100 kyr) eccentricity cycle. Importantly, the phase of AM remains stable during the carbon cycle transfer, thus providing a reference framework against which to evaluate distortion of the 405 kyr term. The phase relationships can help to (1) identify depositional and diagenetic signatures in δ13C and (2) interpret the pathways of astronomical signal through the climate system. The approach is illustrated by case studies of Albian and Oligocene records using a new computational tool EPNOSE (Evaluation of Phase in uNcertain and nOisy SEries). Analogous phase distortions occur in other components of the carbon cycle including atmospheric CO2 levels; hence, to fully understand the causal relationships on astronomical time scales, paleoclimate models may need to incorporate realistic, amplitude-modulated insolation instead of monochromatic sinusoidal approximations. Finally, detection of the lagged δ13C response can help to reduce uncertainties in astrochronological age models that are tuned to the 405 kyr cycle.