Ranges of moisture-source temperature estimated from Antarctic ice cores stable isotope records over glacial–interglacial cycles
Ranges of moisture-source temperature estimated from Antarctic ice cores stable isotope records over glacial–interglacial cycles
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DOI：
10.5194/cp-8-1109-2012
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发表时间：
2012-01
影响因子：
4.3
通讯作者：
R. Uemura;V. Masson‐Delmotte;J. Jouzel;A. Landais;H. Motoyama;B. Stenni
中科院分区：
文献类型：
--
作者：
R. Uemura;V. Masson‐Delmotte;J. Jouzel;A. Landais;H. Motoyama;B. Stenni
在南极冰芯记录中，水的单一同位素比值（δ d或δ 18o）被广泛用作气温代用指标。然而，这些同位素比率不仅取决于气温，而且还取决于从海洋水汽源到降水地点的大气水蒸气中重同位素的蒸馏程度。利用氘过量(d)数据可以反演海洋水汽源（Δ T源）和降水点（Δ T点）的温度变化。本文介绍了来自南极富士圆顶的36万年的新记录，并与来自Vostok和EPICA圆顶C冰芯的记录进行了比较。在以往的研究中，为了获取Δ T源和Δ T位点信息，使用理论同位素蒸馏模型提出了不同的线性回归方程。不确定性的主要来源在于回归系数β位点，β位点与d对Δ T位点的敏感性有关。我们发现，不同的温度范围和同位素模型输出的选择可能使β位的值增加两倍以上。为了探讨该系数对重建温度的影响，我们首次将完全相同的方法应用于南极三个冰芯的同位素记录。我们发现β位系数的不确定性强烈影响(i) Δ T源的冰期-间冰期量级；（ii）倾角在Δ T源和场源温度梯度上的印记。相比之下，我们强调了利用水同位素记录重建Δ T位点的稳健性。
A single isotope ratio (δD or δ 18 O) of water is widely used as an air-temperature proxy in Antarctic ice core records. These isotope ratios, however, do not solely depend on air-temperature but also on the extent of distillation of heavy isotopes out of atmospheric water vapor from an oceanic moisture source to a precipitation site. The temperature changes at the oceanic moisture source (Δ T source ) and at the precipitation site (Δ T site ) can be retrieved by using deuterium-excess ( d ) data. A new d record from Dome Fuji, Antarctica spanning the past 360 000 yr is presented and compared with records from Vostok and EPICA Dome C ice cores. In previous studies, to retrieve Δ T source and Δ T site information, different linear regression equations were proposed using theoretical isotope distillation models. A major source of uncertainty lies in the coefficient of regression, β site which is related to the sensitivity of d to Δ T site . We show that different ranges of temperature and selections of isotopic model outputs may increase the value of β site by more than a factor of two. To explore the impacts of this coefficient on reconstructed temperatures, we apply for the first time the exact same methodology to the isotope records from the three Antarctica ice cores. We show that uncertainties in the β site coefficient strongly affect (i) the glacial–interglacial magnitude of Δ T source ; (ii) the imprint of obliquity in Δ T source and in the site-source temperature gradient. By contrast, we highlight the robustness of Δ T site reconstruction using water isotopes records.