Developing a Coral Proxy System Model to Compare Coral and Climate Model Estimates of Changes in Paleo‐ENSO Variability
Developing a Coral Proxy System Model to Compare Coral and Climate Model Estimates of Changes in Paleo‐ENSO Variability
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DOI：
10.1029/2019pa003836
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发表时间：
2020-07
影响因子：
3.5
通讯作者：
A. Lawman;J. Partin;S. Dee;C. Casadio;P. D. Nezio;T. Quinn
中科院分区：
文献类型：
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作者：
A. Lawman;J. Partin;S. Dee;C. Casadio;P. D. Nezio;T. Quinn
表层海洋状况的珊瑚记录将我们对厄尔尼诺-南方涛动(ENSO)年际变化的知识扩展到仪器前时期。尽管如此，气候系统内广泛的自然变异性以及珊瑚档案固有的多种不确定因素给古气候界利用珊瑚地球化学记录探测ENSO强迫变化带来了挑战。我们提出了一个新的中等复杂性的珊瑚代理系统模型(PSM)，用于评估年际方差的变化。我们的珊瑚PSM为先前发布的传感器模型的传递函数增加了额外的复杂性，这些传递函数描述了档案如何对海洋表面温度(SST)和盐度做出反应。我们使用共同体地球系统模式最后千年集合850控制的SST和盐度输出来模拟珊瑚氧同位素比率和由锶/钙得出的SST。在将分析扩展到更广阔的热带太平洋之前，我们使用中太平洋和西南太平洋地区的气候模式输出对我们的PSM进行了详细的分析。我们展示了可变的增长率、分析和校准误差以及年龄模型假设如何系统性地影响年际方差的估计，并表明年际方差变化的相对大小与位置有关。然而，重要的是，我们发现，即使我们的PSM增加了不确定性，来自环太平洋许多地点的珊瑚基本上能够捕捉到ENSO变率的十年和更长时间(十年+)的变化。我们的代码在GitHub上公开提供，以便于将来模型输出和珊瑚代理数据之间的比较。
Coral records of surface‐ocean conditions extend our knowledge of interannual El Niño–Southern Oscillation (ENSO) variability into the preinstrumental period. That said, the wide range of natural variability within the climate system as well as multiple sources of uncertainties inherent to the coral archive produce challenges for the paleoclimate community to detect forced changes in ENSO using coral geochemical records. We present a new coral proxy system model (PSM) of intermediate complexity, geared toward the evaluation of changes in interannual variance. Our coral PSM adds additional layers of complexity to previously published transfer functions of sensor models that describe how the archive responds to sea surface temperature (SST) and salinity. We use SST and salinity output from the Community Earth System Model Last Millennium Ensemble 850 control to model coral oxygen isotopic ratios and SST derived from Sr/Ca. We present a detailed analysis of our PSM using climate model output for sites in the central and southwest Pacific before extending the analyses to span the broader tropical Pacific. We demonstrate how variable growth rates, analytical and calibration errors, and age model assumptions systematically impact estimates of interannual variance and show that the relative magnitude of the change in interannual variance is location dependent. Importantly, however, we find that even with the added uncertainties in our PSM, corals from many circum‐Pacific locations are broadly able to capture decadal and longer (decadal+) changes in ENSO variability. Our code is publicly available on GitHub to facilitate future comparisons between model output and coral proxy data.