Simulation of stable water isotope variations by the GENESIS GCM for modern conditions
Simulation of stable water isotope variations by the GENESIS GCM for modern conditions
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DOI：
10.1029/2001jd900255
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发表时间：
2002-02-27
影响因子：
4.4
通讯作者：
Thompson, SL
中科院分区：
文献类型：
--
作者：
Mathieu, R;Pollard, D;Thompson, SL
[1]在大气环流模式（GCM）中解释稳定同位素物理学为研究降水中的同位素变异性提供了一种有前途的手段，包括在古气候档案（如冰芯）中引起同位素变异的过程。本文介绍了稳定同位素示踪剂在GENESIS2.0 GCM中的实现和验证。该模型再现了当今同位素场的主要特征和大尺度同位素-气候关系的特征。全球三角洲（18）O-deltaD，温度-三角洲（18）O，和降水-三角洲（18）O的关系进行了很好的模拟，和模拟的区域模式与欧洲大陆上空的水汽循环和垂直梯度与观测结果吻合得很好。在GENESIS中，降水和大气蒸汽之间相互作用的更复杂的参数化有助于更好地模拟干燥气候中的同位素变化。标准模型低估了降水中的全球平均氘过量（deltaD-8delta（18）O），尽管启发式敏感性试验表明，这可以通过考虑海洋上空同位素蒸发分馏的非中性分层来弥补。模拟同位素场的误差进行了分析，以确定它们是由当地的气候偏差的GCM或同位素物理参数化不准确。使用敏感性实验的结果和其他同位素GCM结果的比较，我们确定了主要错误的起源的关键同位素和气候过程，并建议进行额外的研究，以提高同位素模拟。
[1] Incorporating stable isotope physics in a general circulation model (GCM) provides a promising means to study isotopic variability in precipitation, including the processes that cause isotopic variability in paleoclimatic archives such as ice cores. This paper describes the implementation and validation of stable isotope tracers in the GENESIS 2.0 GCM. The model reproduces the main features of present-day isotopic fields and the characteristic large-scale isotope-climate relationships. Global delta(18)O-deltaD, temperature-delta(18)O, and precipitation-delta(18)O relationships are well simulated, and the modeled regional patterns associated with continental vapor recycling over Europe and vertical gradients agree well with observations. In GENESIS a more sophisticated parameterization of interactions between precipitation and atmospheric vapor contributes to a better simulation of isotopic variations in dry climates. The standard model underestimates the global mean deuterium excess (deltaD-8delta(18)O) in precipitation, although a heuristic sensitivity test suggests this may be remedied by accounting for nonneutral stratification in isotopic evaporative fractionation over ocean. Errors in simulated isotopic fields are analyzed to determine whether they are caused by local climatic biases in the GCM or by inaccurate parameterizations of isotope physics. Using the results of sensitivity experiments and comparisons with other isotopic GCM results, we identify key isotopic and climatic processes at the origin of the main errors and suggest additional studies to improve isotope simulations.