Reconstructing seawater δ18O from paired coral δ18O and Sr/Ca ratios:: Methods, error analysis and problems, with examples from Tahiti (French Polynesia) and Timor (Indonesia)
Reconstructing seawater δ18O from paired coral δ18O and Sr/Ca ratios:: Methods, error analysis and problems, with examples from Tahiti (French Polynesia) and Timor (Indonesia)
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DOI：
10.1016/j.gca.2008.04.005
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发表时间：
2008-06-15
影响因子：
5
通讯作者：
Schoenberg, Dieter Garbe
中科院分区：
文献类型：
--
作者：
Cahyarini, Sri Yudawati;Pfeiffer, Miriam;Schoenberg, Dieter Garbe
我们比较了几种统计程序，这些程序可以用来根据成对的珊瑚SR/Ca和增量O-18测量来计算增量O-18和SSS。通常，通过珊瑚三角洲O-18与SST的线性回归来估计三角洲O-18(珊瑚)-SST的关系。如果应用这种方法，应提供证据，证明在特定地点SST和SSS没有共变。在热带海洋中，SST和O-18(西南)(SSS)三角洲的海温经常是协变的，这将对O-18(珊瑚)-SST的回归斜率的估计产生偏差。利用随机模型，我们证明了协方差会导致一元回归方程系数的偏差。由于三角洲O-18(珊瑚)-SST关系的斜率已知，我们建议在回归模型中插入伽马(1)的这个值。这需要删除回归方程的常量。为了省略常量，我们建议将回归方程居中(即从变量中去掉平均值)。统计误差传播的计算是为了评估我们解决O-18(Sw)(SSS)增量过去变化的能力。在塔希提岛，我们发现珊瑚三角洲O-18和锶/钙的综合分析不确定度等于三角洲O-18(Sw)(SSS)季节循环的幅度。因此，我们无法解析塔希提岛SSS的季节周期。在东帝汶，重建的O-18三角洲(Sw)(SSS)的误差小于三角洲O-18(Sw)(SSS)的季节变化幅度，可以分辨出Delta O-18(Sw)(SSS)的季节旋回。(C)2008爱思唯尔有限公司。保留所有权利。
We compare several statistical routines that may be used to calculate delta O-18 and SSS from paired coral Sr/Ca and delta O-18 measurements. Typically, the delta O-18(coral)-SST relationship is estimated by linear regression of coral delta O-18 vs. SST. If this method is applied, evidence should be given that at a particular site SST and SSS do not co-vary. In the tropical oceans, SST and delta O-18(sw) (SSS) often co-vary, and this will bias the estimate of the regression slope of delta O-18(coral)-SST. Using a stochastic model, we show that covariance leads to a bias in the coefficients of the univariate regression equations. As the slope of the delta O-18(coral)-SST relationship has known, we propose to insert this value for gamma(1) in the regression models. This requires that the constants of the regression equations are removed. To omit the constants, we propose to center the regression equations (i.e., to remove the mean values from the variables). The statistical error propagation is calculated to assess our ability to resolve past variations in delta O-18(sw) (SSS). At Tahiti, we find that the combined analytical uncertainties of coral delta O-18 and Sr/Ca equal the amplitude of the seasonal cycle of delta O-18(sw) (SSS). Therefore, we cannot resolve the seasonal cycle of SSS at Tahiti. At Timor, the error of reconstructed delta O-18(sw) (SSS) is lower than the magnitude of seasonal variations of delta O-18(sw) (SSS), and the seasonal cycle of delta O-18(sw) (SSS) can be resolved. (c) 2008 Elsevier Ltd. All rights reserved.