The Connected Isotopic Water Cycle in the Community Earth System Model Version 1
The Connected Isotopic Water Cycle in the Community Earth System Model Version 1
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DOI：
10.1029/2019ms001663
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发表时间：
2019-08-01
影响因子：
6.8
通讯作者：
Zhu, J.
中科院分区：
文献类型：
--
作者：
Brady, E.;Stevenson, S.;Zhu, J.
由于水在地球系统中的普遍作用，水的稳定同位素的相对丰度对于理解大气、海洋和生物圈过程以及解释古气候代理重建具有重要价值。同位素可以通过大尺度流动和湍流流动进行输送，并且重、轻同位素的比例会因分馏而发生变化，分馏可能伴随着冷凝和蒸发过程。正确预测同位素分布需要解决大尺度海洋和大气环流与小尺度水文过程之间的关系，这可以在耦合气候模式框架内完成。在这里，我们介绍了社区地球系统模型版本1 （iCESM1）的水同位素支持版本，它模拟了大气、陆地、海洋和海冰中水同位素比率的全球变化。在覆盖850-2005年期间的短暂的“上千年”模拟中，iCESM1正确地捕获了全球海洋上δ O-18和δ D在20世纪后期的结构，在陆地上的精度更有限。盐度与海水三角洲O-18之间的关系也在观测期内得到了很好的体现，包括盆地间变化。我们使用Last Millennium模拟和iCESM1的淡水软管实验来说明耦合同位素模拟的实用性。关闭耦合模式中所有组分之间的同位素质量平衡，为CESM水循环的潜在描述提供了新的信心，同时也突出了潜在水文平衡可以改善的领域。iCESM1将成为一个重要的社区资源，用于现代和古气候应用的持续模式开发。
Because of the pervasive role of water in the Earth system, the relative abundances of stable isotopologues of water are valuable for understanding atmospheric, oceanic, and biospheric processes, and for interpreting paleoclimate proxy reconstructions. Isotopologues are transported by both large-scale and turbulent flows, and the ratio of heavy to light isotopologues changes due to fractionation that can accompany condensation and evaporation processes. Correctly predicting the isotopic distributions requires resolving the relationships between large-scale ocean and atmospheric circulation and smaller-scale hydrological processes, which can be accomplished within a coupled climate modeling framework. Here we present the water isotope-enabled version of the Community Earth System Model version 1 (iCESM1), which simulates global variations in water isotopic ratios in the atmosphere, land, ocean, and sea ice. In a transient Last Millennium simulation covering the 850-2005 period, iCESM1 correctly captures the late-twentieth-century structure of delta O-18 and delta D over the global oceans, with more limited accuracy over land. The relationship between salinity and seawater delta O-18 is also well represented over the observational period, including interbasin variations. We illustrate the utility of coupled, isotope-enabled simulations using both Last Millennium simulations and freshwater hosing experiments with iCESM1. Closing the isotopic mass balance between all components of the coupled model provides new confidence in the underlying depiction of the water cycle in CESM, while also highlighting areas where the underlying hydrologic balance can be improved. The iCESM1 is poised to be a vital community resource for ongoing model development with both modern and paleoclimate applications.