Quantifying errors in coral-based ENSO estimates: Toward improved forward modeling of δ18O
Quantifying errors in coral-based ENSO estimates: Toward improved forward modeling of δ18O
复制标题
量化基于珊瑚的 ENSO 估计中的误差：改进 δ18O 正演模型
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
B. Fox‐Kemper
中科院分区：
文献类型：
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作者：
S. Stevenson;H. McGregor;S. Phipps;B. Fox‐Kemper
[1]热带太平洋珊瑚骨架的氧同位素比值（δ18O）反映了过去厄尔尼诺-南方涛动（ENSO）的变化，但δ18O-ENSO关系的量化很差。在构建δ18O数据集、组合不同站点的记录以及δ18O与海温（SST）和盐度（SSS）之间的转换时，存在不确定性。在这里，我们使用1958 - 1985年在15个热带太平洋站点的季节分辨δ18O来估计这些误差并评估可能的改进。基里蒂玛蒂、新喀里多尼亚和拉罗汤加的观测不确定性为0.12 ~ 0.14‰，导致典型δ18O方差误差为8 ~ 25%。使用5 ~ 7个站点的多口综合方法可以很好地捕获主成分（PCs），但站点选择对ENSO空间结构有显著影响：使用东太平洋、西太平洋暖池和南太平洋辐合带（SPCZ）的站点可以捕获“东太平洋型”变率，而将暖池和SPCZ的站点结合使用可以最好地观测到“中太平洋型”事件。定量ENSO估计的主要障碍是δ18O/气候转换，这体现在δ18O方差和第一主成分振幅的大误差上，这是由于使用常用的二元公式来将海温和海温与δ18O联系起来造成的。误差可能来自用于伪代理校准的仪器数据或其他过程（δ18O平流/大气分馏等）的影响。在一些站点，对这些影响的季节变化进行建模可将转换误差减少20%。这表明，通过改进δ18O正演模型，可以大大提高对珊瑚δ18O过去ENSO动力学的理解。
[1] The oxygen isotopic ratio (δ18O) in tropical Pacific coral skeletons reflects past El Nino–Southern Oscillation (ENSO) variability, but the δ18O-ENSO relationship is poorly quantified. Uncertainties arise when constructing δ18O data sets, combining records from different sites, and converting between δ18O and sea surface temperature (SST) and salinity (SSS). Here we use seasonally resolved δ18O from 1958 to 1985 at 15 tropical Pacific sites to estimate these errors and evaluate possible improvements. Observational uncertainties from Kiritimati, New Caledonia, and Rarotonga are 0.12–0.14‰, leading to errors of 8–25% on the typical δ18O variance. Multicoral syntheses using five to seven sites capture the principal components (PCs) well, but site selection dramatically influences ENSO spatial structure: Using sites in the eastern Pacific, western Pacific warm pool, and South Pacific Convergence Zone (SPCZ) captures “eastern Pacific-type” variability, while “Central Pacific-type” events are best observed by combining sites in the warm pool and SPCZ. The major obstacle to quantitative ENSO estimation is the δ18O/climate conversion, demonstrated by the large errors on both δ18O variance and the amplitude of the first principal component resulting from the use of commonly employed bivariate formulae to relate SST and SSS to δ18O. Errors likely arise from either the instrumental data used for pseudoproxy calibration or influences from other processes (δ18O advection/atmospheric fractionation, etc.). At some sites, modeling seasonal changes to these influences reduces conversion errors by up to 20%. This indicates that understanding of past ENSO dynamics using coral δ18O could be greatly advanced by improving δ18O forward models.
影响因子：
4.3
作者：
T. Russon;A. Tudhope;G. Hegerl;M. Collins;J. Tindall
通讯作者：
T. Russon;A. Tudhope;G. Hegerl;M. Collins;J. Tindall
影响因子：
5
作者：
Cahyarini, Sri Yudawati;Pfeiffer, Miriam;Schoenberg, Dieter Garbe
通讯作者：
Schoenberg, Dieter Garbe