Modeling and interpretation of stable carbon isotope ratios of ethane in global chemical transport models
Modeling and interpretation of stable carbon isotope ratios of ethane in global chemical transport models
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全球化学品运输模型中乙烷稳定碳同位素比率的建模和解释
DOI：
10.1029/2006jd008062
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发表时间：
2007
影响因子：
--
通讯作者：
J. Rudolph
中科院分区：
文献类型：
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作者：
O. Stein;J. Rudolph
[1] 使用两个全球 3D-CTM（GISS 和 MOZART-2）进行模型计算，其中我们引入了乙烷稳定碳同位素比率。在这两个模型中，VOC 排放均使用基于 EDGAR 数据库的排放清单。我们考虑了来源特定的同位素分馏，并包括同位素比率显着不同的 C3 和 C4 工厂的全球排放量。模型结果与观测结果的比较强烈表明，EDGAR 排放清单低估了全球乙烷排放量约 1.5 倍。根据鲁道夫（Rudolph，1995）报告的乙烷模型预测和大气观测之间随纬度变化的差异，对当前排放清单中缺失的源的强度和纬度范围进行了估计。然而，浓度数据本身仅提供对地理分布的有限限制，并且仅提供有关缺失来源类型的间接信息。同位素比研究对于获得更多见解非常有价值。为了研究排放的地理分布与大气乙烷浓度和同位素比之间的依赖性，进行了 MOZART-2 模型计算，其中所有排放都集中在纬度带以及特定区域。在全球范围内可以区分两种情况：在源纬度带中，背景空气的稀释解释了大部分计算出的浓度变化，而在远离源的纬度上，化学损失是主要过程。
[1] Model calculations with two global 3D-CTMs (GISS and MOZART-2) in which we introduced ethane stable carbon isotopic ratios were performed. In both models, emission inventories based on the EDGAR database are used for VOC emissions. We considered source specific isotope fractionations and included global emissions from C3 and C4 plants which differ significantly in isotope ratio. Comparison of the model results with observation strongly indicates that the EDGAR emission inventory underestimates global ethane emissions by a factor of approximately 1.5. On the basis of the latitude-dependent differences between model predictions and the atmospheric observations of ethane reported by Rudolph (1995), estimates of magnitude and latitude range of sources missing in current emission inventories are made. However, the concentration data alone provide only limited constraints on the geographical distribution and only indirect information about the type of the missing sources. Isotope ratio studies can be very valuable to obtain additional insight. To study the dependence between the geographical distribution of the emissions and atmospheric ethane concentrations and isotope ratios, MOZART-2 model calculations were made where all emissions are concentrated in latitude bands as well as in specified regions. Two regimes can be distinguished on a global scale: In the source latitude band, dilution with background air explains most of the calculated concentration variation, while at latitudes farther away from the sources, chemical loss is the dominating process.