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An assessment of biomarker-based multivariate classification methods versus the PIP25 index for paleo Arctic sea ice reconstruction
Organic Geochemistry ( IF 3 ) Pub Date : 2018-11-01 , DOI: 10.1016/j.orggeochem.2018.08.014
Denizcan Köseoğlu , Simon T. Belt , Katrine Husum , Jochen Knies

Abstract The development of various combinative methods for Arctic sea ice reconstruction using the sympagic highly branched isoprenoid (HBI) IP25 in conjunction with pelagic biomarkers has often facilitated more detailed descriptions of sea ice conditions than using IP25 alone. Here, we investigated the application of the Phytoplankton-IP25 index (PIP25) and a recently proposed Classification Tree (CT) model for describing temporal shifts in sea ice conditions to assess the consistency of both methods. Based on biomarker data from three downcore records from the Barents Sea spanning millennial timescales, we showcase apparent and potential limitations in both approaches, and provide recommendations for their identification or prevention. Both methods provided generally consistent outcomes and, within the studied cores, captured abrupt shifts in sea ice regimes, such as those evident during the Younger Dryas, as well as more gradual trends in sea ice conditions during the Holocene. The most significant discrepancies occurred during periods of highly unstable climate change, such as those characteristic of the Younger Dryas–Holocene transition. Such intervals of increased discrepancy were identifiable by significant changes of HBI distributions and correlations to values not observed in proximal surface sediments. We suggest that periods of highly fluctuating climate that are not represented in modern settings may hinder the performance and complementary application of PIP25 and CT-based methods, and that data visualisation techniques should be employed to identify such occurrences in downcore records. Additionally, due to the reliance of both methods on biomarker distributions, we emphasise the importance of accurate and consistent biomarker quantification.

中文翻译:

基于生物标志物的多元分类方法与 PIP25 指数对古北极海冰重建的评估

摘要 与单独使用 IP25 相比,使用交界高度分支异戊二烯 (HBI) IP25 与远洋生物标志物相结合的北极海冰重建的各种组合方法的开发通常有助于更详细地描述海冰条件。在这里,我们研究了浮游植物-IP25 指数 (PIP25) 和最近提出的分类树 (CT) 模型的应用,用于描述海冰条件的时间变化,以评估两种方法的一致性。基于来自巴伦支海跨越千年时间尺度的三个下行记录的生物标志物数据,我们展示了这两种方法的明显和潜在局限性,并为它们的识别或预防提供了建议。两种方法都提供了普遍一致的结果,并且在研究的核心中,捕捉到海冰状况的突然变化,例如在新仙女木时期明显的变化,以及全新世期间海冰状况的更渐进趋势。最显着的差异发生在高度不稳定的气候变化时期,例如新仙女木-全新世过渡时期的特征。这种差异增加的区间可以通过 HBI 分布的显着变化以及与近端表层沉积物中未观察到的值的相关性来识别。我们建议现代环境中没有表现出的高度波动的气候时期可能会阻碍 PIP25 和基于 CT 的方法的性能和互补应用,并且应采用数据可视化技术来识别下行记录中的此类事件。此外,
更新日期:2018-11-01
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