The recent increase of atmospheric methane from 10 years of ground-based NDACC FTIR observations since 2005
The recent increase of atmospheric methane from 10 years of ground-based NDACC FTIR observations since 2005
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DOI：
10.5194/acp-17-2255-2017
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发表时间：
2017-02
影响因子：
6.3
通讯作者：
Whitney Bader;B. Bovy;S. Conway;K. Strong;D. Smale;A. Turner;T. Blumenstock;C. Boone;M. Coen;A. Coulon;O. García;D. Griffith;F. Hase;P. Hausmann;N. Jones;P. Krummel;I. Murata;I. Morino;H. Nakajima;S. O'Doherty;C. Paton‐Walsh;John Robinson;Rodrigue Sandrin;M. Schneider;C. Servais;R. Sussmann;E. Mahieu
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作者：
Whitney Bader;B. Bovy;S. Conway;K. Strong;D. Smale;A. Turner;T. Blumenstock;C. Boone;M. Coen;A. Coulon;O. García;D. Griffith;F. Hase;P. Hausmann;N. Jones;P. Krummel;I. Murata;I. Morino;H. Nakajima;S. O'Doherty;C. Paton‐Walsh;John Robinson;Rodrigue Sandrin;M. Schneider;C. Servais;R. Sussmann;E. Mahieu
抽象的。自2005年以来，大气甲烷总柱（CH 4）的变化进行了评估，使用傅里叶变换红外（FTIR）太阳观测在10个地面站点，隶属于网络探测大气成分变化（NDACC）。由此，我们发现2005-2014年期间大气甲烷总柱增加了0.31 ± 0.03%（2σ不确定性水平）。在本地和全球范围内与原位甲烷测量的比较显示出良好的一致性。我们使用了GEOS-Chem化学传输模型标记的模拟，该模型考虑了2005-2012年期间每个排放源和一个汇在总甲烷中的贡献。在根据NDACC垂直分层使用保守再网格化方案进行再网格化并通过与相应的FTIR季节平均内核进行卷积进行平滑之后，GEOS-Chem模拟显示，2005年至2012年期间，大气甲烷总柱增加了0.35 ± 0.03%，这与NDACC在同一时间段的测量结果一致（0.30 ± 0.04%年-1，10个站点的平均值）。对GEOS-Chem标记模拟的分析使我们能够量化自2005年以来每种示踪剂对全球甲烷变化的贡献。我们发现，自然来源，如湿地和生物质燃烧有助于甲烷的年际变化。然而，主要在北方半球排放的人为排放，如煤炭开采、天然气和石油运输和勘探，是全球甲烷预算的次要贡献者，在2005年以来观测到的大气甲烷增加中发挥了重要作用。基于GEOS-Chem-taged模拟，我们讨论了自2005年以来甲烷增加的可能原因，这仍然是无法解释的。
Abstract. Changes of atmospheric methane total columns (CH4) since 2005 have been evaluated using Fourier transform infrared (FTIR) solar observations carried out at 10 ground-based sites, affiliated to the Network for Detection of Atmospheric Composition Change (NDACC). From this, we find an increase of atmospheric methane total columns of 0.31 ± 0.03 % year−1 (2σ level of uncertainty) for the 2005–2014 period. Comparisons with in situ methane measurements at both local and global scales show good agreement. We used the GEOS-Chem chemical transport model tagged simulation, which accounts for the contribution of each emission source and one sink in the total methane, simulated over 2005–2012. After regridding according to NDACC vertical layering using a conservative regridding scheme and smoothing by convolving with respective FTIR seasonal averaging kernels, the GEOS-Chem simulation shows an increase of atmospheric methane total columns of 0.35 ± 0.03 % year−1 between 2005 and 2012, which is in agreement with NDACC measurements over the same time period (0.30 ± 0.04 % year−1, averaged over 10 stations). Analysis of the GEOS-Chem-tagged simulation allows us to quantify the contribution of each tracer to the global methane change since 2005. We find that natural sources such as wetlands and biomass burning contribute to the interannual variability of methane. However, anthropogenic emissions, such as coal mining, and gas and oil transport and exploration, which are mainly emitted in the Northern Hemisphere and act as secondary contributors to the global budget of methane, have played a major role in the increase of atmospheric methane observed since 2005. Based on the GEOS-Chem-tagged simulation, we discuss possible cause(s) for the increase of methane since 2005, which is still unexplained.