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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Carbon and hydrogen isotopic compositions of stratospheric methane: 2. Two-dimensional model results and implications for kinetic isotope effects - art. no. 4461
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Carbon and hydrogen isotopic compositions of stratospheric methane: 2. Two-dimensional model results and implications for kinetic isotope effects - art. no. 4461

机译：平流层甲烷的碳和氢同位素组成：2.二维模型结果及其对动力学同位素效应的影响-艺术。没有。 4461

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摘要

New high-precision measurements of the carbon and hydrogen isotopic compositions of stratospheric CH4 made on whole air samples collected aboard the NASA ER-2 aircraft are compared with results from the Lawrence Livermore National Laboratory 2-D model. Model runs incorporating sets of experimentally determined kinetic isotope effects (KIEs) for the reactions of CH4 with each of the oxidants OH, O(D-1), and Cl are examined with the goals of determining (1) how well the 2-D model can reproduce the observations for both the carbon and hydrogen isotopic compositions, (2) what factors are responsible for the observed increase in the apparent isotopic fractionation factors with decreasing methane mixing ratios, and (3) how sensitive the modeled isotopic compositions are to various experimentally determined KIEs. Bound by estimates of the effects of uncertainties in model chemistry and transport on isotopic compositions, we then examine the constraints the ER-2 observations place on values for the KIEs. For the carbon KIE for reaction of CH4 with O(D-1), for example, the analysis of model results and observations favors the larger of the experimental values, 1.013, over a value of 1.001. These analyses also suggest that intercomparisons of results from different models using a given set of KIEs may be useful as a new diagnostic of model-model differences in integrated chemistry and transport. [References: 62]
机译：比较了在NASA ER-2飞机上采集的全部空气样品上平流层CH4的碳和氢同位素组成的新高精度测量结果与劳伦斯·利弗莫尔国家实验室2维模型的结果进行了比较。为了确定（1）2-D的效果，对模型运行进行了合并，该组运行包含一组实验确定的CH4与CH4与氧化剂OH，O（D-1）和Cl的反应的动力学同位素效应（KIE）。该模型可以重现碳和氢同位素组成的观察结果;（2）观察到的表观同位素分馏因子随甲烷混合比降低而增加的因素是什么;（3）建模的同位素组成对各种同位素的敏感性如何实验确定的KIE。受模型化学和运输不确定性对同位素组成影响的估计的约束，我们然后研究了ER-2观测值对KIEs值的约束。例如，对于CH4与O（D-1）反应的碳KIE，对模型结果和观察结果的分析偏爱较大的实验值1.013，而不是1.001的值。这些分析还表明，使用给定的一组KIE，比较来自不同模型的结果可能对整合化学和运输中模型-模型差异的新诊断有用。 [参考：62]

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