Transects of atmospheric CO, CH4, and their isotopic composition across the Pacific: Shipboard measurements and validation of inverse models
Transects of atmospheric CO, CH4, and their isotopic composition across the Pacific: Shipboard measurements and validation of inverse models
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跨太平洋大气 CO、CH4 及其同位素组成的横断面：船上测量和反演模型验证
DOI：
10.1029/2000jd900576
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发表时间：
2001
影响因子：
--
通讯作者：
T. Clarkson
中科院分区：
文献类型：
--
作者：
P. Bergamaschi;D. Lowe;M. Manning;R. Moss;T. Bromley;T. Clarkson
测量一氧化碳，甲烷，和它们的同位素组成的样品收集在1996年和1998年之间的新西兰和美国之间的太平洋六船航行。这些数据涵盖了大约南纬40°至北纬40°的纬度范围，清楚地确定了混合比和同位素组成及其季节变化的重要纬度梯度。将观测数据与最近对全球CO和CH4分布的三维逆建模研究进行比较（Bergamaschi等人，2000 a，B，c）受来自国家海洋和大气管理局气候监测和诊断实验室网络的CO和CH4混合比数据以及来自一组五个全球分布台站的额外同位素测量的约束。因此，船上的测量代表了一个独特的机会，独立验证的逆模型。一般来说，我们看到测量值和模型结果之间非常好的协议，无论是CO和CH4的混合比和它们的稳定同位素组成（δ 13 CO，δ C18 O，δ 13 CH4）。这是特别真实的模拟这些量的平均纬度梯度。然而，在某些航行中，纬度剖面的“精细结构”明显存在重大偏差，这是由于模式没有捕捉到天气尺度的变化（对模式采用了标准气象学）。在大多数情况下，观测结果和模型结果之间的偏差表现出类似的模式，甲烷和CO的混合比的偏差与相应的同位素签名的偏差。此外，CO和乙烷混合比之间的明显相关性是可见的。对14CO的观测表明，在赤道附近有一个普遍的极小值，而在每个半球则有相反相位的周期。1997年在两个半球观测到几乎相同的14CO最小值，表明OH水平相似。我们还在讨论中展示了δ CH 3D和C17 O中质量无关同位素分数的模型结果（尽管缺乏船舶航行的观测数据），以说明这些同位素特征对于理解CH 4和CO的全球循环的潜力。分别。
Measurements of carbon monoxide, methane, and their isotopic composition are presented for samples collected on six ship voyages across the Pacific between New Zealand and the United States between 1996 and 1998. The data cover a latitude range from approximately 40°S to 40°N and clearly define significant latitudinal gradients in mixing ratios and isotopic composition and their seasonal variations. Observational data are compared with recent three-dimensional inverse modeling studies of the global CO and CH4 distributions (Bergamaschi et al., 2000a, b, c) constrained by CO and CH4 mixing ratio data from the National Oceanic and Atmospheric Administration Climate Monitoring and Diagnostics Laboratory network and additional isotope measurements from a set of five globally distributed stations. Thus the shipboard measurements represent a unique opportunity for independent validation of the inverse models. In general, we see a very good agreement between measurements and model results, both for CO and CH4 mixing ratios and their stable isotopic composition (δ13CO, δC18O, δ13CH4). This is in particular true for the simulation of mean latitudinal gradients of these quantities. For some voyages, however, significant deviations in the “fine structure” of the latitudinal profiles are apparent and are attributed to synoptic scale variations that are not captured by the model (for which a standard meteorology is applied). In most cases, deviations between observations and model results exhibit similar patterns for CH4 and CO, and the deviations in mixing ratios are linked with corresponding deviations in the isotopic signature. Furthermore, a clear correlation between CO and ethane mixing ratios is visible. Observations of 14CO show a general minimum around the equator and cycles of opposite phase in each hemisphere. Virtually identical 14CO minima were observed in both hemispheres in 1997, indicating similar OH levels. We also show model results for δCH3D and the mass-independent isotope fraction in C17O (despite the absence of observational data for the ship voyages) in our discussion to illustrate the potential of these isotopic signatures for the understanding of the global cycles of CH4 and CO, respectively.