Water isotope expressions of intrinsic and forced variability in a coupled ocean‐atmosphere model
Water isotope expressions of intrinsic and forced variability in a coupled ocean‐atmosphere model
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DOI：
10.1029/2006jd007781
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发表时间：
2007-05
影响因子：
--
通讯作者：
G. Schmidt;A. Legrande;G. Hoffmann
中科院分区：
文献类型：
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作者：
G. Schmidt;A. Legrande;G. Hoffmann
[1]水同位素清楚地记录了过去的气候变化，但确定它们与当地或区域气候变化的精确关系是定量解释的关键。我们已将水同位素示踪剂纳入戈达德空间研究所海洋-大气耦合模型(MODELE)的完整水文循环，以评估这些关系。利用现代(工业化前)和全新世中期(6KYR BP)气候的多中心模拟，我们检查了内部变率和对轨道和温室气体强迫的强迫响应。模拟的同位素异常清楚地反映了气候变化，特别是在热带地区，与降水异常相比，具有更强的区域一致性。与全新世中期和仪器时期的观测结果吻合很好。我们计算了与全新世相关的许多内在和强迫变率模式的水同位素-气候关系，我们表明，一般而言，校准取决于气候变化的性质。具体地说，我们研究了主要冰芯地区(格陵兰、南极洲和热带安第斯山脉)降水中的同位素与当地温度和降雨量之间的关系，以及海洋中海水的同位素-盐度梯度。我们认为，基于空间模式和非局部校准的基于同位素的气候重建将比基于局部关系的解释更稳健。
[1] Water isotopes provide a clear record of past climate variability but establishing their precise relationship to local or regional climate changes is the key to quantitative interpretations. We have incorporated water isotope tracers within the complete hydrological cycle of Goddard Institute for Space Studies coupled ocean-atmosphere model (ModelE) in order to assess these relationships. Using multicentennial simulations of the modern (preindustrial) and mid-Holocene (6 kyr BP) climate, we examine the internal variability and the forced response to orbital and greenhouse gas forcing. Modelled isotopic anomalies clearly reflect climatic changes and, particularly in the tropics, are more regionally coherent than the precipitation anomalies. Matches to observations at the mid-Holocene and over the instrumental period are good. We calculate water isotope-climate relationships for many patterns of intrinsic and for forced variability relevant to the Holocene, and we show that in general, calibrations depend on the nature of the climate change. Specifically, we examine relationships between isotopes in precipitation and local temperatures and precipitation amounts in the principal ice coring regions (Greenland, Antarctica, and the tropical Andes) and the seawater isotope-salinity gradients in the ocean. We suggest that isotope-based climate reconstructions based on spatial patterns and nonlocal calibrations will be more robust than interpretations based on local relationships.