Atmospheric constraints on the methane emissions from the East Siberian Shelf
Atmospheric constraints on the methane emissions from the East Siberian Shelf
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DOI：
10.5194/acp-16-4147-2016
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发表时间：
2016-01-01
影响因子：
6.3
通讯作者：
Hermansen, Ove
中科院分区：
文献类型：
--
作者：
Berchet, Antoine;Bousquet, Philippe;Hermansen, Ove
东西伯利亚北极大陆架(ESAS)的海底永久冻土和水合物构成了一个巨大的碳库，也是大气中甲烷的潜在来源。以前基于内插海洋运动的研究估计该地区的大气排放量为8-17TGCH(4)Yr(-1)。在这里，我们提出了基于大气观测的见解来评估这些估计。2012年全年大气甲烷摩尔分数的高分辨率模拟与连续甲烷观测的比较证实了ESAS甲烷排放的高度变异性和非均质性。在先前估计排放量的较低部分，ESAS排放量为8TGCH(4)yr(-1)的参考情景被发现在很大程度上高估了冬季的大气观测值，这可能与高估了甲烷通过海冰的泄漏有关。相比之下，在夏季，模拟与观测更一致。根据对观测和模拟的综合统计分析，ESAS的甲烷年排放量估计在0.0到4.5TGCH(4)yr(-1)之间。同位素观测表明，气团中的甲烷来自生物来源(陆地或海洋)，这些甲烷起源于2008年夏末和2009年夏末的ESAS。
Subsea permafrost and hydrates in the East Siberian Arctic Shelf (ESAS) constitute a substantial carbon pool, and a potentially large source of methane to the atmosphere. Previous studies based on interpolated oceanographic campaigns estimated atmospheric emissions from this area at 8-17 TgCH(4) yr(-1). Here, we propose insights based on atmospheric observations to evaluate these estimates. The comparison of high-resolution simulations of atmospheric methane mole fractions to continuous methane observations during the whole year 2012 confirms the high variability and heterogeneity of the methane releases from ESAS. A reference scenario with ESAS emissions of 8 TgCH(4) yr(-1), in the lower part of previously estimated emissions, is found to largely overestimate atmospheric observations in winter, likely related to overestimated methane leakage through sea ice. In contrast, in summer, simulations are more consistent with observations. Based on a comprehensive statistical analysis of the observations and of the simulations, annual methane emissions from ESAS are estimated to range from 0.0 to 4.5 TgCH(4) yr(-1). Isotopic observations suggest a biogenic origin (either terrestrial or marine) of the methane in air masses originating from ESAS during late summer 2008 and 2009.