Stable atmospheric methane in the 2000s: key-role of emissions from natural wetlands
Stable atmospheric methane in the 2000s: key-role of emissions from natural wetlands
复制标题
2000 年代大气甲烷稳定：自然湿地排放的关键作用
DOI：
10.5194/acp-13-11609-2013
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发表时间：
2013
影响因子：
6.3
通讯作者：
F. Papa
中科院分区：
文献类型：
--
作者：
I. Pison;B. Ringeval;P. Bousquet;C. Prigent;F. Papa
两个大气逆温（一个精细解决和一个过程的歧视）和基于过程的陆面交换模型汇集在一起，分析1990年至2009年的甲烷排放量的变化。重点放在自然湿地的作用和2000 - 2006年这一大气浓度稳定的时期。从1990年到2000年，自上而下和自下而上的观点同意全球总量和湿地排放异常的时间阶段。过程判别反演表明，湿地占主导地位的甲烷排放量的时间变异性（90%的总变异性）。热带湿地对异常的贡献很大，尤其是在皮纳图博飓风之后的几年里（全球负异常，1992年最低值在-41和-19 Tg yr（-1）之间）和1997 - 1998年厄尔尼诺/1998 - 1999年拉尼娜交替期间（对于逆温，热带地区的最大异常在+16至+22 Tg yr（-1）之间，对于基于过程的模型，热带湿地的异常在+12至+17 Tg yr（-1）之间）。2000年至2006年，在大气中甲烷浓度停滞期间，自上而下和自下而上的方法都认为南美洲是造成自然湿地排放异常的主要地区，但它们对亚马逊流域通量趋势的迹象和幅度存在分歧。过程判别反演推断出负趋势（-3.9 +/-1.3 Tg yr（-1）），而过程模型发现正趋势（+1.3 +/-0.3 Tg yr（-1））。虽然基于过程的模型有自己的注意事项，可能没有考虑到所有过程，但B-U方法发现的积极趋势被认为更有可能，因为它是基于过程的模型的一个强大特征，与分析的降水量和卫星得出的淹没区范围一致。相反，基于表面数据的反演缺乏对南美洲的约束。这一结果表明，有必要重新解释2000年后人为甲烷清单的大幅增加。
Two atmospheric inversions (one fine-resolved and one process-discriminating) and a process-based model for land surface exchanges are brought together to analyse the variations of methane emissions from 1990 to 2009. A focus is put on the role of natural wetlands and on the years 2000-2006, a period of stable atmospheric concentrations. From 1990 to 2000, the top-down and bottom-up visions agree on the time-phasing of global total and wetland emission anomalies. The process-discriminating inversion indicates that wetlands dominate the time-variability of methane emissions (90% of the total variability). The contribution of tropical wetlands to the anomalies is found to be large, especially during the post-Pinatubo years (global negative anomalies with minima between -41 and -19 Tg yr(-1) in 1992) and during the alternate 1997-1998 El-Nino/1998-1999 La-Nina (maximal anomalies in tropical regions between +16 and +22 Tg yr(-1) for the inversions and anomalies due to tropical wetlands between +12 and +17 Tg yr(-1) for the process-based model). Between 2000 and 2006, during the stagnation of methane concentrations in the atmosphere, the top-down and bottom-up approaches agree on the fact that South America is the main region contributing to anomalies in natural wetland emissions, but they disagree on the sign and magnitude of the flux trend in the Amazon basin. A negative trend (-3.9 +/- 1.3 Tg yr(-1)) is inferred by the process-discriminating inversion whereas a positive trend (+1.3 +/- 0.3 Tg yr(-1)) is found by the process model. Although processed-based models have their own caveats and may not take into account all processes, the positive trend found by the B-U approach is considered more likely because it is a robust feature of the process-based model, consistent with analysed precipitations and the satellite-derived extent of inundated areas. On the contrary, the surface-data based inversions lack constraints for South America. This result suggests the need for a re-interpretation of the large increase found in anthropogenic methane inventories after 2000.