Evaluating year-to-year anomalies in tropical wetland methane emissions using satellite CH4 observations
Evaluating year-to-year anomalies in tropical wetland methane emissions using satellite CH4 observations
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DOI：
10.1016/j.rse.2018.02.011
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发表时间：
2018-06-15
影响因子：
13.5
通讯作者：
Bloom, A. Anthony
中科院分区：
文献类型：
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作者：
Parker, Robert J.;Boesch, Hartmut;Bloom, A. Anthony
天然湿地是甲烷排放的最大来源，占全球排放量的20-40%，并主导着年际变化。大的不确定性仍然存在的变化和对气候变化的响应。本研究使用GOSAT卫星的大气甲烷观测，以评估甲烷湿地排放量的估计。我们评估如何以及模拟重现所观察到的甲烷年际变化，通过评估的趋势的季节性周期。纬度的手段同意，但在热带的28.1-34.8 ppb的最大差异表明，所有的模拟未能捕捉到的热带湿地的季节cycle.We的范围内的主要天然湿地在南美洲：季节性洪水泛滥的热带草原的潘塔纳尔（巴西）和Llanos de Moxos（玻利维亚）地区;和巴拉那河（阿根廷）形成的河流湿地进一步分析。我们看到2010年、2011年和2014年潘塔纳尔和Llanos de Moxos地区以及2010年和2014年巴拉那河地区的模拟和观测之间存在很大差异。我们发现这些甲烷异常的时间和位置与湿地范围的变化之间存在高度一致的行为，我们的结论是，陆面模式无法通过漫滩淹没来增加湿地范围是这些观测到的差异的主要原因，并可能导致甲烷通量低估多达50%（5.3-11.8 Tg yr（-1））。由于这些地区的水文与厄尔尼诺/南方涛动变化密切相关，能够再现湿地行为的变化对于成功预测其甲烷排放量至关重要。
Natural wetlands are the largest source of methane emissions, contributing 20-40% of global emissions and dominating the inter-annual variability. Large uncertainties remain on their variability and response to climate change.This study uses atmospheric methane observations from the GOSAT satellite to evaluate methane wetland emission estimates. We assess how well simulations reproduce the observed methane inter-annual variability by evaluating the detrended seasonal cycle. The latitudinal means agree well but maximum differences in the tropics of 28.1-34.8 ppb suggest that all simulations fail to capture the extent of the tropical wetland seasonal cycle.We focus further analysis on the major natural wetlands in South America: the seasonally flooded savannah of the Pantanal (Brazil) and Llanos de Moxos (Bolivia) regions; and the riverine wetlands formed by the Parana River (Argentina). We see large discrepancies between simulation and observation over the Pantanal and Llanos de Moxos region in 2010, 2011 and 2014 and over the Parana River region in 2010 and 2014. We find highly consistent behaviour between the time and location of these methane anomalies and the change in wetland extent, driven by precipitation related to El Nino Southern Oscillation activity.We conclude that the inability of land surface models to increase wetland extent through overbank inundation is the primary cause of these observed discrepancies and can lead to under-estimation of methane fluxes by as much as 50% (5.3-11.8 Tg yr(-1)) of the observed emissions for the combined Pantanal and Parana regions. As the hydrology of these regions is heavily linked to ENSO variability, being able to reproduce changes in wetland behaviour is important for successfully predicting their methane emissions.