High-time resolution measurements of atmospheric methane by use of cavity enhanced absorption spectroscopy

为了准确测量大气中的甲烷浓度，研制了一种基于激光的腔增强吸收光谱（CEAS）技术的大气甲烷浓度测量仪。所开发的仪器的检测限达到1 ppb的1秒信号平均，这是足够高的实时检测大气甲烷。在日本滋贺的日本柏树林中，利用该仪器调查了森林冠层上方和内部甲烷的时空行为。一个自动室测量系统耦合到激光为基础的仪器在这项研究中开发的，从而叶片，树干，森林土壤和大气之间的甲烷交换通量进行了计算。室通量获得15分钟的时间分辨率。

A laser-based instrument using a technique of cavity enhanced absorption spectroscopy (CEAS) was developed to measure atmospheric methane accurately and precisely. The limit-of-detection of the developed instrument achieved 1 ppb for 1 second signal averaging, which is enough high to detect atmospheric methane on a real-time basis. The instrument was utilized in a Japanese cypress forest in Shiga prefecture, Japan, to investigate the spatio-temporal behavior of methane above and within the forest canopy. An automated chamber measurement system was coupled to the laser-based instrument developed in this study, thereby methane exchange fluxes between the foliage, trunk, and forest soils and the atmosphere were calculated. The chamber fluxes were obtained with 15-min time resolution.