Analysis of the characteristics of methane in the coal mining area of southeastern Shanxi with eddy and mobile observation

Methane is the second largest greenhouse gas in the world after carbon dioxide. Its lifetime in the atmos⁃ phere is only about 10 years，but its global warming potential is dozens of times that of CO2. The concentration of methane in the atmosphere can respond more quickly to greenhouse emission reduction activities. Compared with CO2 emission reduction，controlling and reducing methane emission is one of the most effective means to cope with cli⁃ mate change in the short term. The coal mining industry is one of the main sources of methane emissions in China. Un⁃ der the national strategic needs of carbon peaking and carbon neutrality，the control and utilization of methane emis⁃ sions from coal activities will definitely become the focus of China’ s methane emission control actions during the “14th Five⁃Year Plan” period. It is of great significance to reveal the characteristics of methane emissions in the coal mining industry. The methane emissions from coal mining activities are affected by many factors，such as geo⁃ logical occurrence，mining methods，and utilization conditions. The traditional “bottom⁃up” emission factor invento⁃ ry method has great uncertainty. The “top⁃down” technique based on the observational data of atmospheric meth⁃ ane concentration is becoming an important method for monitoring and accounting for methane emissions. In the au⁃ tumn and winter of 2021，this study has adopted the observation method of “fixed + mobile”，and obtained some first⁃hand observation data over the typical high methane emission area in China ( the coal mining area of southeastern Shanxi) so as to analyze and reveal the characteristics of near⁃surface methane concentration and its po⁃ tential emission sources. The results show that 1 The methane concentration has strong temporal and spatial variability，the background methane concentration in the coal mining area is nearly 1.7 times that of the clean back⁃ ground，and the extreme high value can reach more than 40 to 50 times the background value. 2 The changes of methane concentration within a day are closely related to coal production activity，and the day⁃to⁃day changes are greatly affected by meteorological diffusion conditions. 3 Most of the high methane concentrations are located in the areas related to coal mine production，but due to the influence of diffusion，coal production has a significant im⁃ pact on the spatiotemporal methane concentration. The distribution influence has certain spatial deviation and time lag. The ground “fixed + mobile” observation method can provide refined methane emission characteristic information. Furthermore，the research conclusions can lay a foundation for constructing a “top⁃down” methane emission inventory from the coal industry based on observations.