Comparing laser-based open- and closed-path gas analyzers to measure methane fluxes using the eddy covariance method
Comparing laser-based open- and closed-path gas analyzers to measure methane fluxes using the eddy covariance method
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DOI：
10.1016/j.agrformet.2011.05.014
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发表时间：
2011-10-15
影响因子：
6.2
通讯作者：
Baldocchi, Dennis
中科院分区：
文献类型：
--
作者：
Detto, Matteo;Verfaillie, Joseph;Baldocchi, Dennis
封闭式和开放式甲烷气体分析仪用于涡度协方差系统，以比较萨克拉门托-圣华金三角洲（CA，美国）的三个潜在的甲烷排放生态系统：稻田，泥炭地牧场和恢复湿地。指出了两种系统在野外试验和数据处理方面的异同点。封闭路径系统，尽管与声波风速计的侵入性较低，需要更多的照顾和权力。相比之下，开放路径系统似乎更通用的远程和无人值守的实验场所。总的来说，这两个系统具有可比的最低可检测极限，但风速和甲烷数据，空气密度校正和光谱损失之间的同步计算通量协方差有不同的影响。对于闭合路径分析仪，空气密度效应不太重要，但是当通量小或使用尺寸过小的泵时，同步和光谱损失可能是一个问题。由于光谱效应和经典的Webb-Pearman-Leuning校正，开路分析仪的空气密度校正更大。30分钟通量之间的比较揭示了良好的协议，在开放路径和封闭路径通量系统之间的幅度。然而，由于两个系统都需要密集的数据处理，因此分散性很大。由爱思唯尔公司出版
Closed- and open-path methane gas analyzers are used in eddy covariance systems to compare three potential methane emitting ecosystems in the Sacramento-San Joaquin Delta (CA, USA): a rice field, a peatland pasture and a restored wetland. The study points out similarities and differences of the systems in field experiments and data processing. The closed-path system, despite a less intrusive placement with the sonic anemometer, required more care and power. In contrast, the open-path system appears more versatile for a remote and unattended experimental site. Overall, the two systems have comparable minimum detectable limits, but synchronization between wind speed and methane data, air density corrections and spectral losses have different impacts on the computed flux covariances. For the closed-path analyzer, air density effects are less important, but the synchronization and spectral losses may represent a problem when fluxes are small or when an undersized pump is used. For the open-path analyzer air density corrections are greater, due to spectroscopy effects and the classic Webb-Pearman-Leuning correction. Comparison between the 30-min fluxes reveals good agreement in terms of magnitudes between open-path and closed-path flux systems. However, the scatter is large, as consequence of the intensive data processing which both systems require. Published by Elsevier B.V.