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首页> 外文学位 >Constraining methane flux estimates using observations of atmospheric methane and carbon-13/carbon-12 isotopic ratios in methane .
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Constraining methane flux estimates using observations of atmospheric methane and carbon-13/carbon-12 isotopic ratios in methane .

机译：约束甲烷通量估计使用大气中的甲烷和甲烷中碳13 /碳12同位素比的观测。

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Understanding the budget of CH4 is crucial to predicting climate change and managing earth's carbon reservoirs. CH4 is the second most important anthropogenic greenhouse gas, contributing about 20% to the total radiative forcing from long-lived, globally mixed greenhouse gases. In addition, CH4 has a significant impact on atmospheric chemistry, affecting OH, O3, and CO mixing ratios in the troposphere and O 3 and Cl in the stratosphere. At present, many of the sources and sinks of CH4 are poorly understood due in part to the large spatial and temporal variability of the sources.; Model simulations of CH4 mixing ratios using bottom-up source estimates typically over-predict the latitudinal gradient of atmospheric CH 4 relative to the observations; however, the specific source processes responsible for this discrepancy have not been identified definitively. The aim of this work is to employ the differing isotopic signatures of the source processes to add an additional constraint to the CH4 budget and attribute discrepancies between bottom-up source estimates and observations of CH4 in the atmosphere to a source process or group of source processes.; To this end, observations of CH4 and 13C/ 12C isotopic ratios in CH4 are used in conjunction with an inverse model of the CH4 budget. Inverse modeling is a top-down approach which uses observations of trace gases in the atmosphere, an estimate of the spatial pattern of trace gas fluxes, and a model of atmospheric transport to estimate the sources and sinks. Global and regional estimates of CH 4 fluxes are presented that are consistent with the atmospheric observations of CH4, observations of the 13C/12C isotopic ratios, and process-level understanding of sources using two complimentary approaches to the CH4 inverse problem. Both approaches imply interesting differences from previous methane budget estimates, most notably a large increase in the tropical biomass burning source and the tropical and southern extra tropical wetland sources and a decrease in emissions from rice cultivation and fossil sources. In several cases, the inverse estimates are supported by recent process studies, known anomalies in climate, and other model-independent information.
机译：了解CH 4 的预算对于预测气候变化和管理地球的碳库至关重要。 CH 4 是第二重要的人为温室气体，占全球长期存在的混合温室气体的总辐射强迫的20％。此外，CH 4 对大气化学有显着影响，影响对流层和O 3 中的OH，O 3 和CO混合比和Cl在平流层中。目前，对CH 4 的许多源和汇的了解不多，部分原因是这些源的时空变化很大。使用自下而上的源估计法对CH 4 混合比的模型模拟通常会高估相对于观测值的大气CH 4 的纬度梯度。但是，尚未明确确定造成此差异的特定源过程。这项工作的目的是利用源过程的不同同位素特征为CH 4 预算增加附加约束，并实现自下而上的源估计与CH 4观测值之间的属性差异。 在大气中到一个源过程或一组源过程。为此，我们在CH 4 中使用了CH 4 和 13 C / 12 C同位素比的观测结果。与CH 4 预算的逆模型结合。逆建模是一种自上而下的方法，它使用对大气中痕量气体的观测，对痕量气体通量的空间模式的估计以及大气传输模型来估计源和汇。提出了CH 4 通量的全球和区域估计，与CH 4 的大气观测， 13 C / 12 C同位素比率，并使用两种互补的方法解决CH 4 反问题的过程级来源。两种方法都暗示了与先前甲烷预算估计值的有趣差异，最显着的是热带生物质燃烧源以及热带和南部额外热带湿地源的大量增加，以及稻米种植和化石源的排放量减少。在某些情况下，最近的过程研究，已知的气候异常以及其他与模型无关的信息都支持了逆估计。

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